title:
Memory effects in biochemical networks as the natural counterpart of
  extrinsic noise

abstract:
  We show that in the generic situation where a biological network, e.g. a
protein interaction network, is in fact a subnetwork embedded in a larger
"bulk" network, the presence of the bulk causes not just extrinsic noise but
also memory effects. This means that the dynamics of the subnetwork will depend
not only on its present state, but also its past. We use projection techniques
to get explicit expressions for the memory functions that encode such memory
effects, for generic protein interaction networks involving binary and unary
reactions such as complex formation and phosphorylation, respectively.
Remarkably, in the limit of low intrinsic copy-number noise such expressions
can be obtained even for nonlinear dependences on the past. We illustrate the
method with examples from a protein interaction network around epidermal growth
factor receptor (EGFR), which is relevant to cancer signalling. These examples
demonstrate that inclusion of memory terms is not only important conceptually
but also leads to substantially higher quantitative accuracy in the predicted
subnetwork dynamics.


title:
Helicity-Flux-Driven Alpha Effect in Laboratory and Astrophysical
  Plasmas

abstract:
  The constraint imposed by magnetic helicity conservation on the alpha effect
is considered for both magnetically and flow dominated self-organizing plasmas.
Direct numerical simulations are presented for a dominant contribution to the
alpha effect, which can be cast in the functional form of a total divergence of
an averaged helicity flux, called the helicity-flux-driven alpha ( H$\alpha$)
effect. Direct numerical simulations of the H$\alpha$ effect are prese nted for
two examples---the magnetically dominated toroidal plasma unstable to tearing
modes, and the flow-dominated accretion disk.


title: Making MILES better for stellar population modelling

abstract:
  In order to build more realistic single stellar population (SSP) models with
variable alpha-enhancement, we have recently determined [Mg/Fe] in a uniform
scale with a precision of about 0.1 dex for 752 stars in the MILES empirical
library. The [alpha/Fe] abundance ratio is commonly used as a good temporal
scale indicator of star formation, taking Mg as a template for alpha elements.
Calcium is another element whose abundance is currently being investigated for
the MILES stars. The MILES library is also being expanded by around 20% by
including stars with known Teff, log g, [Fe/H] and [Mg/Fe]. The transformation
of their photospheric parameters to the MILES system has been carried out, but
the calibration of their [Mg/Fe] is still in progress. In parallel, C, N and O
abundances are also being compiled from literature for the library stars
because they play an important role in the photospheric opacity, particularly
influencing the blue spectral region. The Galactic kinematic classification of
MILES stars with compiled [Mg/Fe] has been just computed such that this
information can be considered in the SSP modeling. Comparisons of theoretical
stellar predictions of the Lick line-strength indices against the MILES data
have revealed the good behaviour of Fe-sensitive indices predictions, while
highlighting areas for improvement in some models for the higher order H-Balmer
features.


title:
Analytical approach for the approximate solution of the longitudinal
  structure function with respect to the GLR-MQ equation at small x

abstract:
  We show that the nonlinear corrections to the longitudinal structure function
can be tamed the singularity behavior at low x values, with respect to GLR-MQ
equations. This approach can determined the shadowing longitudinal structure
function based on the shadowing corrections to the gluon and singlet quark
structure functions. Comparing our results with HERA data show that at very low
x this behavior completely tamed by these corrections.


title:
On the Stability of Stochastic Parametrically Forced Equations with Rank
  One Forcing

abstract:
  We derive simplified formulas for analyzing the stability of stochastic
parametrically forced linear systems. This extends the results in [T. Blass and
L.A. Romero, SIAM J. Control Optim. 51(2):1099--1127, 2013] where, assuming the
stochastic excitation is small, the stability of such systems was computed
using a weighted sum of the extended power spectral density over the
eigenvalues of the unperturbed operator. In this paper, we show how to convert
this to a sum over the residues of the extended power spectral density. For
systems where the parametric forcing term is a rank one matrix, this leads to
an enormous simplification.


title: CP violating phase from charged-lepton mixing

abstract:
  A model independent analysis of the leptonic Dirac CP-violating phase
({\delta}) is presented. The analysis uses the experimentally determined values
of the mixing angles in the lepton mixing matrix in order to explore the
allowed values for {\delta} and possible general forms for the charged lepton
mixing matrix. This is done under two general assumptions: 1) that the mixing
matrix in the neutrino sector is the so-called tribimaximal matrix and hence
the non zero value for {\theta}13 arises due to the mixing matrix in the
charged lepton sector and 2) the charged lepton mixing matrix is parametrized
in terms of three angles and one phase. It is found that any value of {\delta}
is still consistent with the data and that, considering the assumptions above,
regardless of the value for {\delta}, the 1-3 mixing angle in the charged
lepton sector is small but non zero and the 2-3 mixing angle can take values in
only two possible small ranges around 0 and {\pi}/2 respectively.


title:
A singular-potential random matrix model arising in mean-field glassy
  systems

abstract:
  We consider an invariant random matrix model where the standard Gaussian
potential is distorted by an additional single pole of order $m$. We compute
the average or macroscopic spectral density in the limit of large matrix size,
solving the loop equation with the additional constraint of vanishing trace on
average. The density is generally supported on two disconnected intervals lying
on the two sides of the pole. In the limit of having no pole, we recover the
standard semicircle. Obtained in the planar limit, our results apply to
matrices with orthogonal, unitary or symplectic symmetry alike. The orthogonal
case with $m=2$ is motivated by an application to spin glass physics. In the
Sherrington-Kirkpatrick mean-field model, in the paramagnetic phase and for
sufficiently large systems the spin glass susceptibility is a random variable,
depending on the realization of disorder. It is essentially given by a linear
statistics on the eigenvalues of the coupling matrix. As such its large
deviation function can be computed using standard Coulomb fluid techniques. The
resulting free energy of the associated fluid precisely corresponds to the
partition function of our random matrix model. Numerical simulations provide an
excellent confirmation of our analytical results.

categories: math-ph cond-mat.dis-nn cond-mat.stat-mech math.MP


title:
Self-gravitating Newtonian models of fermions with anisotropy and cutoff
  energy in their distribution function

abstract:
  Systems of self-gravitating fermions constitute a topic of great interest in
astrophysics, due to the wide field of applications. In this paper, we consider
the gravitational equilibrium of spherically symmetric Newtonian models of
collisionless semidegenerate fermions. We construct numerical solutions by
taking into account the effects of the anisotropy in the distribution function
and considering the prevalence of tangential velocity. In this way, our models
generalize the solutions obtained for isotropic Fermi-Dirac statistics. We also
extend the analysis to equilibrium configurations in the classical regime and
in the fully degenerate limit, recovering, for different levels of anisotropy,
hollow equilibrium configurations obtained in Maxwellian regime. Moreover, in
the limit of full degeneracy, we find a direct expression relating the
anisotropy with the mass of the particles composing the system.


title:
The evolution of carrying capacity in constrained and expanding tumour
  cell populations

abstract:
  Cancer cells are known to modify their micro-environment such that it can
sustain a larger population, or, in ecological terms, they construct a niche
which increases the carrying capacity of the population. It has however been
argued that niche construction, which benefits all cells in the tumour, would
be selected against since cheaters could reap the benefits without paying the
cost. We have investigated the impact of niche specificity on tumour evolution
using an individual based model of breast tumour growth, in which the carrying
capacity of each cell consists of two components: an intrinsic,
subclone-specific part and a contribution from all neighbouring cells. Analysis
of the model shows that the ability of a mutant to invade a resident population
depends strongly on the specificity. When specificity is low selection is
mostly on growth rate, while high specificity shifts selection towards
increased carrying capacity. Further, we show that the long-term evolution of
the system can be predicted using adaptive dynamics. By comparing the results
from a spatially structured vs.\ well-mixed population we show that spatial
structure restores selection for carrying capacity even at zero specificity,
which a poses solution to the niche construction dilemma. Lastly, we show that
an expanding population exhibits spatially variable selection pressure, where
cells at the leading edge exhibit higher growth rate and lower carrying
capacity than those at the centre of the tumour.


title:
Loschmidt echo and dynamical fidelity in periodically driven quantum
  systems

abstract:
  We study the dynamical fidelity $\mathcal{F} (t)$ and the Loschmidt echo
$\mathcal{L} (t)$, following a periodic driving of the transverse magnetic
field of a quantum Ising chain (back and forth across the quantum critical
point) by calculating the overlap between the initial ground state and the
state reached after $n$ periods $\tau$. We show that
$\log{\mathcal{F}}(n\tau)/L$ (the logarithm of the fidelity per-site) reaches a
steady value in the asymptotic limit $n\to \infty$, and we derive an exact
analytical expression for this quantity. Remarkably, the steady state value of
$[\log{\mathcal{F}}(n\tau\to \infty)]/L$ shows memory of non-trivial phase
information which is instead hidden in the case of thermodynamic quantities;
this conclusion, moreover, is not restricted to 1-dimensional models.


title: A Quick Overview On Regular Algebraic K-Theory For Groups

abstract:
  The paper gives a short account of the contents of "Regular Algebraic
K-Theory For Groups" by the author and its connections with other homology and
K-theories.


title:
Topology-driven instabilities: the theory of pattern formation on
  directed networks

abstract:
  The theory of pattern formation in reaction-diffusion systems is extended to
the case of a directed network. Due to the structure of the network Laplacian
of the scrutinised system, the dispersion relation has both real and imaginary
parts, at variance with the conventional case for a symmetric network. It is
found that the homogeneous fixed point can become unstable due to the topology
of the network, resulting in a new class of instabilities which cannot be
induced on undirected graphs. Results from a linear stability analysis allow
the instability region to be analytically traced. Numerical simulations show
that the instability can lead to travelling waves, or quasi-stationary
patterns, depending on the characteristics of the underlying graph. The results
presented here could impact on the diverse range of disciplines where directed
networks are found, such as neuroscience, computer networks and traffic
systems.


title: Higher Inductive Types as Homotopy-Initial Algebras

abstract:
  Homotopy Type Theory is a new field of mathematics based on the surprising
and elegant correspondence between Martin-Lofs constructive type theory and
abstract homotopy theory. We have a powerful interplay between these
disciplines - we can use geometric intuition to formulate new concepts in type
theory and, conversely, use type-theoretic machinery to verify and often
simplify existing mathematical proofs. A crucial ingredient in this new system
are higher inductive types, which allow us to represent objects such as
spheres, tori, pushouts, and quotients. We investigate a variant of higher
inductive types whose computational behavior is determined up to a higher path.
We show that in this setting, higher inductive types are characterized by the
universal property of being a homotopy-initial algebra.


title:
Hard- Pomeron behavior of the Longitudinal Structure Function $F_{L}$ in
  the Next- to- Leading- Order at low $x$

abstract:
  We present an analytic formula to extract the longitudinal structure function
in the next- to -leading order of the perturbation theory at low $x$, from the
Regge- like behavior of the gluon distribution and the structure function at
this limit. In this approach, the longitudinal structure function has the hard-
Pomeron behavior. The determined values are compared with the $H1$ data and
MRST model. All results can consistently be described within the framework of
perturbative QCD which essentially show increases as $x$ decreases.


title: Trace class conditions for functions of Schr\"odinger operators

abstract:
  We consider the difference $f(-\Delta +V)-f(-\Delta)$ of functions of
Schr\"odinger operators in $L^2(\mathbb R^d)$ and provide conditions under
which this difference is trace class. We are particularly interested in
non-smooth functions $f$ and in $V$ belonging only to some $L^p$ space. This is
motivated by applications in mathematical physics related to Lieb--Thirring
inequalities. We show that in the particular case of Schr\"odinger operators
the well-known sufficient conditions on $f$, based on a general operator
theoretic result due to V. Peller, can be considerably relaxed. We prove
similar theorems for $f(-\Delta +V)-f(-\Delta)-\frac{d}{d\alpha} f(-\Delta
+\alpha V)|_{\alpha=0}$. Our key idea is the use of the limiting absorption
principle.


title: Pebbling on $C_{4k+3}\times G$ and $M(C_{2n})\times G$

abstract:
  The pebbling number of a graph $G$, $f(G)$, is the least $p$ such that,
however $p$ pebbles are placed on the vertices of $G$, we can move a pebble to
any vertex by a sequence of moves, each move taking two pebbles off one vertex
and placing one on an adjacent vertex. It is conjectured that for all graphs
$G$ and $H$, $f(G\times H)\leq f(G)f(H)$. If the graph $G$ satisfies the odd
two-pebbling property, we will prove that $f(C_{4k+3}\times G)\leq
f(C_{4k+3})f(G)$ and $f(M(C_{2n})\times G)\leq f(M(C_{2n}))f(G)$, where
$C_{4k+3}$ is the odd cycle of order $4k+3$ and $M(C_{2n})$ is the middle graph
of the even cycle $C_{2n}$.


title: A state change in the low-mass X-ray binary XSS J12270-4859

abstract:
  Millisecond radio pulsars acquire their rapid rotation rates through mass and
angular momentum transfer in a low-mass X-ray binary system. Recent studies of
PSR J1824-2452I and PSR J1023+0038 have observationally demonstrated this link,
and they have also shown that such systems can repeatedly transition
back-and-forth between the radio millisecond pulsar and low-mass X-ray binary
states. This also suggests that a fraction of such systems are not newly born
radio millisecond pulsars but are rather suspended in a back-and-forth state
switching phase, perhaps for giga-years. XSS J12270-4859 has been previously
suggested to be a low-mass X-ray binary, and until recently the only such
system to be seen at MeV-GeV energies. We present radio, optical and X-ray
observations that offer compelling evidence that XSS J12270-4859 is a low-mass
X-ray binary which transitioned to a radio millisecond pulsar state between
2012 November 14 and 2012 December 21. Though radio pulsations remain to be
detected, we use optical and X-ray photometry/spectroscopy to show that the
system has undergone a sudden dimming and no longer shows evidence for an
accretion disk. The optical observations constrain the orbital period to
6.913+-0.002 hr.


title: On the nature of the 'hostless' short GRBs

abstract:
  A significant proportion ($\sim30\%$) of the short-duration gamma-ray bursts
(SGRBs) localised by Swift have no detected host galaxy coincident with the
burst location to deep limits, and also no high-likelihood association with
proximate galaxies on the sky. These SGRBs may represent a population at
moderately high redshifts ($z\gtrsim1$), for which the hosts are faint, or a
population where the progenitor has been kicked far from its host or is sited
in an outlying globular cluster. We consider the afterglow and host
observations of three 'hostless' bursts (GRBs 090305A, 091109B and 111020A),
coupled with a new observational diagnostic to aid the association of SGRBs
with putative host galaxies to investigate this issue. Considering the well
localised SGRB sample, 7/25 SGRBs can be classified as 'hostless' by our
diagnostic. Statistically, however, the proximity of these seven SGRBs to
nearby galaxies is higher than is seen for random positions on the sky. This
suggests that the majority of 'hostless' SGRBs have likely been kicked from
proximate galaxies at moderate redshift. Though this result still suggests only
a small proportion of SGRBs will be within the AdLIGO horizon for NS-NS or
NS-BH inspiral detection ($z\sim0.1$), in the particular case of GRB 111020A a
plausible host candidate is at $z=0.02$.


title:
Surface corrugations influence on monolayer graphene electromagnetic
  response

abstract:
  We consider the corrugated monolayer graphene membrane electromagnetic (from
both valleys) response in terahertz range. We study the generated in irradiated
graphene total current for the first time taking into account both the
synthetic electric fields arising due to the (inevitable) presence in graphene
of inherent out-of-plane nanodeformations and the double-valleys energy
spectrum of Dirac charge particles. Our approach is based on atomistic quantum
mechanics used for the description of valence ${\pi}-{\sigma}$ bonds changes
generated by activating external periodic electric field and also for mechanism
of Dirac electron interaction with this time-dependent perturbation. We
consider the problem in the framework of the model of noninteracting Dirac
electrons. Assuming surface corrugations not to be very rough we obtain for
weak fields the formula for the total current induced in graphene membrane. Our
formula describes the curved current lines in the linear in $E^{ext}(t)$
approximation for the given graphene surface form. We show that the local
direction of current lines is determined by synthetic electric field whose
direction may essentially differ from the one of the external field and depends
on the local curvature of the graphene membrane. We also demonstrate that
valley currents generated by the external field have nonzero elliptic
polarization angles depending on the point (x,y). Valley currents are shown to
rotate in opposite directions in different valleys. The results obtained below
can be applied to the analysis of different devices in terahertz optics and
optoelectronics and the imaging experiments at the Dirac point.


title:
The approximation method for calculation of the exponent of the gluon
  distribution-$\lambda_{g}$ and the structure function-$\lambda_{S}$ at low
  $x$

abstract:
  We present a set of formulae using the solution of the QCD
Dokshitzer-Gribov-Lipatov-Altarelli-parisi (DGLAP) evolution equation to the
extract of the exponent $\lambda_g$ gluon distribution and $\lambda_S$
structure function from the Regge- like behavior at low $x$. The exponents are
found to be independent of $x$ and to increase linearly with ln$Q^{2}$ and
compared with the most data from H1 Collaboration. We also calculated the
structure function $F_{2}(x,Q^{2})$ and the gluon distribution $G(x,Q^{2})$ at
low $x$ assuming the Regge- like behavior of the gluon distribution function at
this limit and compared with NLO QCD fit to the H$1$ data, two Pomeron fit,
multipole Pomeron exchange fit and MRST (A.D.Martin, R.G.Roberts, W.J.Stirling
and R.S.Thorne), DL(A.Donnachie and P.V.Landshoff), NLO-GRV(M.Gluk, E.Reya and
A.Vogt) fit results, respectively.


title:
Centralised versus Decentralised Active Control of Boundary Layer
  Instabilities

abstract:
  We use linear control theory to construct an output feedback controller for
the attenuation of small-amplitude Tollmien-Schlichting (TS) wavepackets in a
flat-plate boundary layer.We distribute evenly in the spanwise direction up to
72 localized objects near the wall (18 disturbances sources, 18 actuators, 18
estimation sensors and 18 objective sensors). In a fully three-dimensional
configuration,the interconnection between inputs and outputs becomes quickly
unfeasible when the number of actuators and sensors increases in the spanswise
direction. The objective of this work is to understand how an efficient
controller may be designed by connecting only a subset of the actuators to
sensors, thereby reducing the complexity of the controller, without comprising
the efficiency. We find that using a semi-decentralized approach - where small
control units consisting of 3 estimation sensors connected to 3 actuators are
replicated 6 times along the spanwise direction - results only in a 11%
reduction of control performance. Our results reveal that the best performance
is obtained for a control unit which (i) is sufficiently wide to account for
the full spanwise scale of the wavepacket when it reaches the actuators and
(ii) is designed to account for the perturbations which are coming from the
lateral sides (crosstalk) of the estimation sensors. We have also found that
the influence of crosstalk is not as essential as the spreading effect.


title:
Searches for $\Lambda^0_{b}$ and $\Xi^{0}_{b}$ decays to $K^0_{\rm S} p
  \pi^{-}$ and $K^0_{\rm S}p K^{-}$ final states with first observation of the
  $\Lambda^0_{b} \rightarrow K^0_{\rm S}p \pi^{-}$ decay

abstract:
  A search for previously unobserved decays of beauty baryons to the final
states $K^0_{\rm\scriptscriptstyle S} p \pi^{-}$ and
$K^0_{\rm\scriptscriptstyle S}p K^{-}$ is reported. The analysis is based on a
data sample corresponding to an integrated luminosity of $1.0\,$fb$^{-1}$ of
$pp$ collisions. The $\Lambda^0_{b} \rightarrow \overline{\kern -0.2em
K}^0_{\rm\scriptscriptstyle S}p \pi^{-}$ decay is observed with a significance
of $8.6\,\sigma$, with branching fraction \begin{eqnarray*}
  {\cal{B}}(\Lambda^0_{b} \rightarrow \overline{\kern -0.2em K}^0 p \pi^{-}) &
= & \left(1.26 \pm 0.19 \pm 0.09 \pm 0.34 \pm 0.05 \right) \times 10^{-5} \,,
\end{eqnarray*} where the uncertainties are statistical, systematic, from the
ratio of fragmentation fractions $f_{\Lambda}/f_{d}$, and from the branching
fraction of the $B^0 \rightarrow K^0_{\rm\scriptscriptstyle S}\pi^{+}\pi^{-}$
normalisation channel, respectively. A first measurement is made of the $CP$
asymmetry, giving \begin{eqnarray*}
  A_{C/!P} (\Lambda^0_{b} \rightarrow \overline{\kern -0.2em K}^0 p \pi^{-}) &
= & 0.22 \pm 0.13\mathrm{\,(stat)} \pm 0.03\mathrm{\,(syst)} \, .
\end{eqnarray*} No significant signals are seen for $\Lambda^0_{b} \rightarrow
K^0_{\rm\scriptscriptstyle S}p K^{-}$ decays, $\Xi^{0}_{b}$ decays to both the
$K^0_{\rm\scriptscriptstyle S}p \pi^{-}$ and $K^0_{\rm\scriptscriptstyle S}p
K^{-}$ final states, and the $\Lambda^0_{b} \rightarrow D^{-}_{s} (\rightarrow
K^0_{\rm\scriptscriptstyle S} K^{-}) p$ decay, and upper limits on their
branching fractions are reported.


title: Violation of geometric scaling in DIS due to Coulomb corrections

abstract:
  I compute the Coulomb correction to the total and diffractive cross sections
for virtual photon scattering off a heavy nucleus at low $x$. I show that it
violates the geometric scaling in a wide range of photon virtualities and is
weakly $x$-independent. In heavy nuclei at low $Q^2$ the Coulomb correction to
the total and diffractive cross sections is about 20% and 40% correspondingly.


title: Latin Polytopes

abstract:
  Latin squares are well studied combinatorial objects. In this paper we
generalize the concept and propose new objects like Latin triangles, free Latin
squares, Latin tetrahedra, free Latin cubes, etc. We start with a classic
definition of Latin squares followed by one based on the concept of latinized
board. A Latin square appears then as a combinatorial design whose points are
geometric and whose lines (the rows and columns) are invariant under the
symmetries of the square.
  The generalization that follows proceeds by 1. broadening this geometric
symmetry 2. considering more general configurations of points and 3. admitting
lines that intersect more freely. The resulting concept is the Latin board.
Finally, we particularize Latin boards to define Latin polytopes, Latin
polygons and Latin polyhedra.


title:
On linearly related sequences of difference derivatives of discrete
  orthogonal polynomials

abstract:
  Let D_v the difference operator and q-difference operators defined by
D_\omega p(x) = \frac{p(x+\omega)-p(x)}{\omega} and D_q p(x) =
\frac{p(qx)-p(x)}{(q-1)x}, respectively. Let U and V be two moment regular
linear functionals and let (P_n)_n and Q_n)_n be their corresponding orthogonal
polynomial sequences (OPS). We discuss an inverse problem in the theory of
discrete orthogonal polynomials involving the above two OPS assuming that their
difference derivatives $D_\nu$ of higher orders m and k (resp.) are connected
by a linear algebraic structure relation such as $$ \sum_{i=0}^M a_{i,n}
D_\nu^m P_{n+m-i}(x) = \sum_{i=0}^N b_{i,n} D_\nu^k Q_{n+k-i}(x), \quad n\geq
0, $$ where $M,N,m,k=0,1,2,... Under certain conditions, we prove that U and V
are related by a rational factor \c{c} (in the distributional sense). Moreover,
when m\neq k then both U and V are D_v-semiclassical functionals. This leads us
to the concept of (M,N)-D_v-coherent pair of order (m,k) extending to the
discrete case several previous works. As an application we consider the OPS
with respect to a certain following Sobolev-type discrete inner product.


title: The statistics of frictional families

abstract:
  We develop a theoretical description for mechanically stable frictional
packings in terms of the difference between the total number of contacts
required for isostatic packings of frictionless disks and the number of
contacts in frictional packings, $m=N_c^0-N_c$. The saddle order $m$ represents
the number of unconstrained degrees of freedom that a static packing would
possess if friction were removed. Using a novel numerical method that allows us
to enumerate disk packings for each $m$, we show that the probability to obtain
a packing with saddle order $m$ at a given static friction coefficient $\mu$,
$P_m(\mu)$, can be expressed as a power-series in $\mu$. Using this form for
$P_m(\mu)$, we quantitatively describe the dependence of the average contact
number on friction coefficient for static disk packings obtained from direct
simulations of the Cundall-Strack model for all $\mu$ and $N$.


title: Noncommutative covering projections and $K$-homology

abstract:
  If $X$ is a topological space then there is a natural homomorphism
$\pi_1(X)\rightarrow K_1(X)$ from a fundamental group to a $K_1$-homology
group. Covering projections depend of fundamental group. So $K_1$-homology
groups are interrelated with covering projections. This article is concerned
with a noncommutative analogue of this interrelationship.


title:
Permutation symmetry in spinor quantum gases: selection rules,
  conservation laws, and correlations

abstract:
  Many-body systems of identical arbitrary-spin particles, with separable spin
and spatial degrees of freedom, are considered. Their eigenstates can be
classified by Young diagrams, corresponding to non-trivial permutation
symmetries (beyond the conventional paradigm of symmetric--antisymmetric
states).
  The present work obtains (a) selection rules for additional non-separable
(dependent on spins and coordinates) $k$-body interactions: the Young diagrams,
associated with the initial and the final states of a transition, can differ by
relocation of no more than $k$ boxes between their rows; and (b) correlation
rules: eigenstate-averaged local correlations of $k$ particles vanish if $k$
exceeds the number of columns (for bosons) or rows (for fermions) in the
associated Young diagram. It also elucidates the physical meaning of the
quantities conserved due to permutation symmetry --- in 1929, Dirac identified
those with characters of the symmetric group --- relating them to
experimentally observable correlations of several particles.
  The results provide a way to control the formation of entangled states
belonging to multidimensional non-Abelian representations of the symmetric
group. These states can find applications in quantum computation and metrology.

categories: cond-mat.quant-gas math-ph math.MP physics.atom-ph quant-ph


title:
Interpreting $Z_c(3900)$ and $Z_c(4025)/Z_c(4020)$ as charged tetraquark
  states

abstract:
  In the framework of color flux-tube model with a four-body confinement
potential, the lowest charged tetraquark states
$[Qq][\bar{Q}'\bar{q}']~(Q=c,b,q=u,d,s)$ are studied by using the variational
method, Gaussian expansion method. The results indicate that some compact
resonance states can be formed, the states can not decay into two color singlet
mesons $Q\bar{q}'$ and $\bar{Q}'q$ through the breakdown and recombination of
color flux tubes but into $Q\bar{Q}'$ and $q\bar{q}'$. The four-body
confinement potential is an crucial dynamical mechanism for the formation of
states, The decay mechanism is similar to that of compound nucleus and
therefore the states should be called "color confined, multi-quark resonance"
states. The newly observed charged states $Z_c(3900)$ and $Z_c(4025)/Z_c(4020)$
can be accommodated in the color flux-tube model and can be interpreted as the
$S$-wave tetraquark states $[cu][{\bar{c}\bar{d}}]$ with quantum numbers $I=1$
and $J=1$ and 2, respectively.


title:
Uniqueness and stability result for Cauchy's equation of motion for a
  certain class of hyperelastic materials

abstract:
  We consider Cauchy's equation of motion for hyperelastic materials. The
solution of this nonlinear initial-boundary value problem is the vector field
which discribes the displacement which a particle of this material perceives
when exposed to stress and external forces. This equation is of greatest
relevance when investigating the behaviour of elastic, anisotropic composites
and for the detection of defects in such materials from boundary measurements.
This is why results on unique solvability and continuous dependence from the
initial values are of large interest in materials research and structural
health monitoring. In this article we present such a result, provided that
reasonable smoothness assumptions for the displacement field and the boundary
of the domain are satisfied, for a certain class of hyperelastic materials
where the first Piola-Kirchhoff tensor is written as a conic combination of
finitely many given tensors.


title:
UNLocBoX: A MATLAB convex optimization toolbox for proximal-splitting
  methods

abstract:
  Convex optimization is an essential tool for machine learning, as many of its
problems can be formulated as minimization problems of specific objective
functions. While there is a large variety of algorithms available to solve
convex problems, we can argue that it becomes more and more important to focus
on efficient, scalable methods that can deal with big data. When the objective
function can be written as a sum of "simple" terms, proximal splitting methods
are a good choice. UNLocBoX is a MATLAB library that implements many of these
methods, designed to solve convex optimization problems of the form $\min_{x
\in \mathbb{R}^N} \sum_{n=1}^K f_n(x).$ It contains the most recent solvers
such as FISTA, Douglas-Rachford, SDMM as well a primal dual techniques such as
Chambolle-Pock and forward-backward-forward. It also includes an extensive list
of common proximal operators that can be combined, allowing for a quick
implementation of a large variety of convex problems.


title: Model performance indicators ERP systems

abstract:
  Implementation process ERP is complex and expensive process. Typically always
be faced with many failures. Successfully implemented in an organization has
many challenges. Organizations in the deployment and success of the system
depends on several factors.One of the key factors in the successful deployment
of systems methodology is the implementation process. Methodology has several
indicators for successful implementation of ERP systems, we have examined. And
indicators for each of the methodologies have identified. The proposed method
is also an important indicator of the success of security controls and
indicators to be monitored and controlled.


title: Covering spaces of character varieties

abstract:
  Let F be a finitely generated discrete group. Given a covering map H to G of
Lie groups with G either compact or complex reductive, there is an induced
covering map Hom(F, H) to Hom(F, G). We show that when the fundamental group of
G is torsion-free and F is free, free Abelian, or the fundamental group of a
closed Riemann surface M of genus g, this map induces a covering map between
the corresponding moduli spaces of representations. We give conditions under
which this map is actually the universal covering, leading to new information
regarding fundamental groups of these moduli spaces. Let pi be the fundamental
group of M. As an application, we show that for g>0, the stable moduli space
Hom(pi, SU)/SU is homotopy equivalent to infinite complex projective space.
  In the Appendix by Ho and Liu, it is shown show that there is a bijection
between the number of connected components of Hom(pi, G) and the fundamental
group of [G,G] for all complex connected reductive Lie groups G.


title:
Floquet calculation of harmonic generation from hydrogen molecular ions
  in strong monochromatic laser fields

abstract:
  We present Floquet calculations of high harmonic generation (HHG) for the
lowest two electronic states of the $\mbox{H}_2^+$ ion by strong
continuous-wave laser fields. We solve the non-Hermitian matrix problem to get
accurate solutions to the periodic time-dependent Schr\"odinger equation (TDSE)
by applying a pseudospectral representation combined with a complex absorbing
potential method. This represents an alternative approach to direct TDSE
solutions to obtain the harmonic spectra for the ion. We compare our HHG rates
for the lower and upper states of $\mbox{H}^{+}_{2}$, which correspond to the
gerade and ungerade ground states in the field-free case, with previously
obtained results in the literature. We show that the enhancement of the
ionization rates at the critical internuclear separation $R_{c}\approx 8\,au$
plays some role in the appearance of very strong harmonic orders $n=5-11$ at
$\lambda = 1064\,nm$ and $n=5-9$ at $\lambda = 800\,nm$ and intensity
$I=10^{14}\,W/cm^{2}$.


title:
Appearance of an accretion disk perturbed by fractional Brownian Motion
  density

abstract:
  This paper aims to investigate/map the effects that perturbations applied to
an accretion disk might produce on the registered Light Curves (LC). The case
of accretion disks around supermassive active black holes (AGNs) is studied
with the goal to explain some of the statistical properties of the observed
IntraDay Variability (IDV). The region producing optical IDV is perturbed by
allowing it to develop a mass density of a fractional Brownian Motion-like
type. The light curves and spectral slopes are calculated and compared to
observational data for different Hurst parameters. The spectral slopes of the
simulated light curves vary in the range $(0.4,2.5)$. The agreement with
observational data shows that a magnetized disk subjected to stochastic
perturbations can produce some of the features observed in the light curves.


title: Nonstandard functional interpretations and categorical models

abstract:
  Recently, the second author, Briseid and Safarik introduced nonstandard
Dialectica, a functional interpretation that is capable of eliminating
instances of familiar principles of nonstandard arithmetic - including
overspill, underspill, and generalisations to higher types - from proofs. We
show that, under few metatheoretical assumptions, the properties of this
interpretation are mirrored by first order logic in a constructive sheaf model
of nonstandard arithmetic due to Moerdijk, later developed by Palmgren. In
doing so, we also draw some new connections between nonstandard principles, and
principles that are rejected by strict constructivism.
  Furthermore, we introduce a variant of the Diller-Nahm interpretion with two
different kinds of quantifiers (with and without computational meaning),
similar to Hernest's light Dialectica interpretation, and show that one can
obtain nonstandard Dialectica from this by weakening the computational content
of the existential quantifiers -- a process we call herbrandisation. We also
define a constructive sheaf model mirroring this new functional interpretation
and show that the process of herbrandisation has a clear meaning in terms of
these sheaf models.


title: Signal to Noise Ratio in Lensless Compressive Imaging

abstract:
  We analyze the signal to noise ratio (SNR) in a lensless compressive imaging
(LCI) architecture. The architecture consists of a sensor of a single detecting
element and an aperture assembly of an array of programmable elements. LCI can
be used in conjunction with compressive sensing to capture images in a
compressed form of compressive measurements. In this paper, we perform SNR
analysis of the LCI and compare it with imaging with a pinhole or a lens. We
will show that the SNR in the LCI is independent of the image resolution, while
the SNR in either pinhole aperture imaging or lens aperture imaging decreases
as the image resolution increases. Consequently, the SNR in the LCI is much
higher if the image resolution is large enough.


title: Maslov indices, Poisson brackets, and singular differential forms

abstract:
  Maslov indices are integers that appear in semiclassical wave functions and
quantization conditions. They are often notoriously difficult to compute. We
present methods of computing the Maslov index that rely only on typically
elementary Poisson brackets and simple linear algebra. We also present a
singular differential form, whose integral along a curve gives the Maslov index
of that curve. The form is closed but not exact, and transforms by an exact
differential under canonical transformations. We illustrate the method with the
$6j$-symbol, which is important in angular momentum theory and in quantum
gravity.


title:
micrOMEGAs : a code for the calculation of Dark Matter properties in
  generic models of particle interaction

abstract:
  These lecture notes describe the micrOMEGAs code for the calculation of Dark
Matter observables in extensions of the standard model.


title: Earth and Moon orbital anomalies

abstract:
  A time-dependent gravitational constant or mass would correctly describe the
suspected increasing of both: the Astronomical unit and the eccentricity of the
Lunar orbit around the Earth.


title:
Analytic Approach to the Approximate Solution of the Independent DGLAP
  Evolution Equations with Respect to the Hard-Pomeron Behavior

abstract:
  We show that it is possible to use hard-Pomeron behavior to the gluon
distribution and singlet structure function at low $x$. We derive a
second-order independent differential equation for the gluon distribution and
the singlet structure function. In this approach, both singlet quarks and
gluons have the same high-energy behavior at small $x$. These equations are
derived from the next-to-leading order DGLAP evolution equations. All results
can be consistently described in the framework of perturbative QCD, which shows
an increase of gluon distribution and singlet structure functions as $x$
decreases.


title:
Detecting Memory and Structure in Human Navigation Patterns Using Markov
  Chain Models of Varying Order

abstract:
  One of the most frequently used models for understanding human navigation on
the Web is the Markov chain model, where Web pages are represented as states
and hyperlinks as probabilities of navigating from one page to another.
Predominantly, human navigation on the Web has been thought to satisfy the
memoryless Markov property stating that the next page a user visits only
depends on her current page and not on previously visited ones. This idea has
found its way in numerous applications such as Google's PageRank algorithm and
others. Recently, new studies suggested that human navigation may better be
modeled using higher order Markov chain models, i.e., the next page depends on
a longer history of past clicks. Yet, this finding is preliminary and does not
account for the higher complexity of higher order Markov chain models which is
why the memoryless model is still widely used. In this work we thoroughly
present a diverse array of advanced inference methods for determining the
appropriate Markov chain order. We highlight strengths and weaknesses of each
method and apply them for investigating memory and structure of human
navigation on the Web. Our experiments reveal that the complexity of higher
order models grows faster than their utility, and thus we confirm that the
memoryless model represents a quite practical model for human navigation on a
page level. However, when we expand our analysis to a topical level, where we
abstract away from specific page transitions to transitions between topics, we
find that the memoryless assumption is violated and specific regularities can
be observed. We report results from experiments with two types of navigational
datasets (goal-oriented vs. free form) and observe interesting structural
differences that make a strong argument for more contextual studies of human
navigation in future work.


title:
Operation of a planar-electrode ion-trap array with adjustable RF
  electrodes

abstract:
  One path to realizing systems of trapped atomic ions suitable for large-scale
quantum computing and simulation is to create a two-dimensional array of ion
traps. Interactions between nearest-neighbouring ions could then be turned on
and off by tuning the ions' relative positions and frequencies. We demonstrate
and characterize the operation of a planar-electrode ion-trap array. Driving
the trap with a network of phase-locked radio-frequency (RF) resonators which
provide independently variable voltage amplitudes we vary the position and
motional frequency of a 40Ca+ ion in two dimensions within the trap array. With
suitable miniaturization of the trap structure, this provides a viable
architecture for large-scale quantum simulations.


title: Trace Formula For Two Variables

abstract:
  A natural generalization of Krein's theorem to a pair of commuting tuples
$\left(H_1^0,H_2^0\right)$ and $\left(H_1,H_2\right)$ of bounded self-adjoint
operators in a separable Hilbert space $\mathcal{H}$ with $H_j-H_j^0 = V_j\in
\mathcal{B}_2(\mathcal{H})$(set of all Hilbert-Schmidt operators on
$\mathcal{H}$) for $j=1,2,$ leads to a Stokes-like formula under trace. A major
ingredient in the proof is the finite-dimensional approximation result for
commuting self-adjoint n-tuples of operators, a generalization of Weyl-von
Neumann-Berg's theorem.


title:
Astrophysical weak-interaction rates for selected $A=20$ and $A=24$
  nuclei

abstract:
  We have evaluated the electron capture rates on $^{20}$Ne, $^{20}$F,
$^{24}$Mg, $^{24}$Na and the $\beta$ decay rates for $^{20}$F and $^{24}$Na at
temperature and density conditions relevant for the late-evolution stages of
stars with $M=8$-12 M$_\odot$. The rates are based on recent experimental data
and large-scale shell model calculations. We show that the electron capture
rates on $^{20}$Ne, $^{24}$Mg and the $^{20}$F, $^{24}$Na $\beta$-decay rates
are based on data in this astrophysical range, except for the capture rate on
$^{20}$Ne, which we predict to have a dominating contribution from the
second-forbidden transition between the $^{20}$Ne and $^{20}$F ground states in
the density range $\log \rho Y_e (\mathrm{g~cm}^{-3}) = 9.3$-9.6. The dominance
of a few individual transitions allows us to present the various rates by
analytical expressions at the relevant astrophysical conditions. We also derive
the screening corrections to the rates.


title: A Game Theoretic Analysis of Collaboration in Wikipedia

abstract:
  Peer production projects such as Wikipedia or open-source software
development allow volunteers to collectively create knowledge based products.
The inclusive nature of such projects poses difficult challenges for ensuring
trustworthiness and combating vandalism. Prior studies in the area deal with
descriptive aspects of peer production, failing to capture the idea that while
contributors collaborate, they also compete for status in the community and for
imposing their views on the product. In this paper we investigate collaborative
authoring in Wikipedia where contributors append and overwrite previous
contributions to a page. We assume that a contributors goal is to maximize
ownership of content sections such that content owned (or originated) by her
survived the most recent revision of the page. We model contributors
interactions to increase their content ownership as a noncooperative game where
a players utility is associated with content owned and cost is a function of
effort expended. Our results capture several real life aspects of contributors
interactions within peer production projects. We show that at the Nash
equilibrium there is an inverse relationship between the effort required to
make a contribution and the survival of a contributors content. In other words
majority of the content that survives is necessarily contributed by experts who
expend relatively less effort than non experts. An empirical analysis of
Wikipedia articles provides support for our models predictions. Implications
for research and practice are discussed in the context of trustworthy
collaboration as well as vandalism.


title: The Mathematics of Fels Sculptures

abstract:
  We give a purely mathematical interpretation and construction of sculptures
rendered by one of the authors, known herein as Fels sculptures. We also show
that the mathematical framework underlying Ferguson's sculpture, {\it The
Ariadne Torus}, may be considered a special case of the more general
constructions presented here. More general discussions are also presented about
the creation of such sculptures whether they be virtual or in higher
dimensional space.


title: Sequential Model-Based Ensemble Optimization

abstract:
  One of the most tedious tasks in the application of machine learning is model
selection, i.e. hyperparameter selection. Fortunately, recent progress has been
made in the automation of this process, through the use of sequential
model-based optimization (SMBO) methods. This can be used to optimize a
cross-validation performance of a learning algorithm over the value of its
hyperparameters. However, it is well known that ensembles of learned models
almost consistently outperform a single model, even if properly selected. In
this paper, we thus propose an extension of SMBO methods that automatically
constructs such ensembles. This method builds on a recently proposed ensemble
construction paradigm known as agnostic Bayesian learning. In experiments on 22
regression and 39 classification data sets, we confirm the success of this
proposed approach, which is able to outperform model selection with SMBO.


title: Extensions and traces of functions of bounded variation on metric spaces

abstract:
  In the setting of a metric space equipped with a doubling measure and
supporting a Poincar\'e inequality, and based on results by Bj\"orn and
Shanmugalingam (2007), we show that functions of bounded variation can be
extended from any bounded uniform domain to the whole space. Closely related to
extensions is the concept of boundary traces, which have previously been
studied by Hakkarainen et al. (2014). On spaces that satisfy a suitable
locality condition for sets of finite perimeter, we establish some basic
results for the traces of functions of bounded variation. Our analysis of
traces also produces novel results on the behavior of functions of bounded
variation in their jump sets.


title:
Isgur-Wise functions, Bjorken-Uraltsev Sum Rules and their Lorentz group
  interpretation, In Memoriam Nikolai Uraltsev

abstract:
  In the heavy quark limit of QCD, using the Operator Product Expansion and the
non-forward amplitude, as proposed by Nikolai Uraltsev, we formulate sum rules
that generalize Bjorken and Uraltsev sum rules. We recover the Uraltsev lower
bound for the slope of the Isgur-Wise (IW) function, that we generalize to
higher derivatives. We show that these results have a clear interpretation in
terms of the Lorentz group, since the IW function is given by an overlap
between the initial and final light clouds, related by Lorentz transformations.
Both the Lorentz group and the Sum Rules approach are equivalent. Moreover, we
formulate an integral representation of the IW function with a positive
measure. Inverting this integral formula, we obtain the measure in terms of the
IW function, allowing to formulate criteria to decide if a given ansatz for the
IW function is compatible or not with the sum rule constraints. We compare
these theoretical constraints to some forms proposed in the literature.


title: Transversals as generating sets in finitely generated groups

abstract:
  We explore transversals of finite index subgroups of finitely generated
groups. We show that when $H$ is a subgroup of a rank $n$ group $G$ and $H$ has
index at least $n$ in $G$ then we can construct a left transversal for $H$
which contains a generating set of size $n$ for $G$, and that the construction
is algorithmic when $G$ is finitely presented. We also show that, in the case
where $G$ has rank $n \leq3$, there is a simultaneous left-right transversal
for $H$ which contains a generating set of size $n$ for $G$. We finish by
showing that if $H$ is a subgroup of a rank $n$ group $G$ with index less than
$3 \cdot 2^{n-1}$, and $H$ contains no primitive elements of $G$, then $H$ is
normal in $G$ and $G/H \cong C_{2}^{n}$.


title: More on Asymptotic behaviors of 9j Coefficients

abstract:
  Previouslywe noted in numerical calculations that a certain unitary ninej
coefficient U9j =((jj)^{2j} (jj)^{2j} | (jj)^{2j} (jj) ^{(2j-2)})^{I} decreases
with increasing j and for small I the decrease is of the form C j^{m}
e^{-\alpha j} . The exponential decay dominates. It is here shown that \alpha =
4 ln(2) and m=3/2.

categories: nucl-th physics.atm-clus physics.atom-ph quant-ph


title:
Surgery along star shaped plumbings and exotic smooth structures on
  4-manifolds

abstract:
  We define a new 4-dimensional symplectic cut and paste operation which is
analogous to Fintushel and Stern's rational blow-down. We use this operation to
produce multiple constructions of symplectic smoothly exotic complex projective
space blown-up eight times, seven times, and six times. We also show how this
operation can be used in conjunction with knot surgery to construct an infinite
family of minimal exotic smooth structures on the complex projective space
blown-up seven times.


title: Equations of Motion for Variational Electrodynamics

abstract:
  We extend the variational problem of Wheeler-Feynman electrodynamics by
putting the electromagnetic functional in a local space of absolutely
continuous trajectories possessing a derivative (velocities) of bounded
variation. Generalizing the calculus of variations for extrema with a finite
number of velocity discontinuities (breaking points), we prove that the
critical-point-conditions for the two-body problem in the extended local space
are Euler-Lagrange equations holding Lebesgue-almost-everywhere plus the
generalized Weierstrass-Erdmann conditions that (i) the partial momenta must be
absolutely continuous functions and (ii) the Legendre transforms of the partial
Lagrangians (i.e, the partial energies) must be absolutely continuous
functions.


title: Mode density and frequency extraction in the delta Scuti star HD 50844

abstract:
  We consider the high mode density reported in the delta Scuti star HD 50844
observed by CoRoT. Using simulations, we find that extracting frequencies down
to a given false alarm probability by means of successive prewhitening leads to
a gross over-estimate of the number of frequencies in a star. This is due to
blending of the peaks in the periodogram due to the finite duration of the time
series. Prewhitening is equivalent to adding a frequency to the data which is
carefully chosen to interfere destructively with a given frequency in the data.
Since the frequency extracted from a blended peak is not quite correct, the
interference is not destructive with the result that many additional fictitious
frequencies are added to the data. In data with very high signal-to-noise, such
as the CoRoT data, these spurious frequencies are highly significant.
Continuous prewhitening thus causes a cascade of spurious frequencies which
leads to a much larger estimate of the mode density than is actually the case.
The results reported for HD 50844 are consistent with this effect. Direct
comparison of the power in the raw periodogram in this star with that in delta
Scuti stars observed by Kepler shows that HD 50844 has a typical mode density.


title:
A Measurement-based Analysis of the Energy Consumption of Data Center
  Servers

abstract:
  Energy consumption is a growing issue in data centers, impacting their
economic viability and their public image. In this work we empirically
characterize the power and energy consumed by different types of servers. In
particular, in order to understand the behavior of their energy and power
consumption, we perform measurements in different servers. In each of them, we
exhaustively measure the power consumed by the CPU, the disk, and the network
interface under different configurations, identifying the optimal operational
levels. One interesting conclusion of our study is that the curve that defines
the minimal CPU power as a function of the load is neither linear nor purely
convex as has been previously assumed. Moreover, we find that the efficiency of
the various server components can be maximized by tuning the CPU frequency and
the number of active cores as a function of the system and network load, while
the block size of I/O operations should be always maximized by applications. We
also show how to estimate the energy consumed by an application as a function
of some simple parameters, like the CPU load, and the disk and network
activity. We validate the proposed approach by accurately estimating the energy
of a map-reduce computation in a Hadoop platform.


title: On the vanishing of Hochster's theta invariant

abstract:
  Hochster's theta invariant is defined for a pair of finitely generated
modules on a hypersurface ring having only an isolated singularity. Up to a
sign, it agrees with the Euler invariant of a pair of matrix factorizations.
  Working over the complex numbers, Buchweitz and van Straten have established
an interesting connection between Hochster's theta invariant and the classical
linking form on the link of the singularity. In particular, they establish the
vanishing of the theta invariant if the hypersurface is even-dimensional by
exploiting the fact that the (reduced) cohomology of the Milnor fiber is
concentrated in odd degrees in this situation.
  In this paper, we give purely algebraic versions of some of these results. In
particular, we establish the vanishing of the theta invariant for isolated
hypersurface singularities of odd dimension in characteristic p > 0, under some
mild extra assumptions. This confirms, in a large number of cases, a conjecture
of Hailong Dao.


title:
Partition Function in One, Two and Three Spatial Dimensions from
  Effective Lagrangian Field Theory

abstract:
  The systematic effective Lagrangian method was first formulated in the
context of the strong interaction: chiral perturbation theory (CHPT) is the
effective theory of Quantum Chromodynamics (QCD). It was then pointed out that
the method can be transferred to the nonrelativistic domain -- in particular,
to describe the low-energy properties of ferromagnets. Interestingly, whereas
for Lorentz-invariant systems the effective Lagrangian method fails in one
spatial dimension ($d_s$=1), it perfectly works for nonrelativistic systems in
$d_s$=1. In the present brief review, we give an outline of the method and then
focus on the partition function for ferromagnetic spin chains, ferromagnetic
films and ferromagnetic crystals up to three loops in the perturbative
expansion -- an accuracy never achieved by conventional condensed matter
methods. We then compare ferromagnets in $d_s$=1,2,3 with the behavior of QCD
at low temperatures by considering the pressure and the order parameter. The
two apparently very different systems (ferromagnets and QCD) are related from a
universal point of view based on the spontaneously broken symmetry. In either
case, the low-energy dynamics is described by an effective theory containing
Goldstone bosons as basic degrees of freedom.


title: Efficient real frequency solver for dynamical mean field theory

abstract:
  We here present how a self-consistent solution of the dynamical mean field
theory equations can be obtained using exact diagonalization of an Anderson
impurity model with accuracies comparable to those found using renormalization
group or quantum Monte Carlo methods. We show how one can solve a correlated
quantum impurity coupled to several hundred uncorrelated bath sites, using a
restricted active basis set. The number of bath sites determines the resolution
of the obtained spectral function, which consists of peaks roughly spaced by
the band width divided by the number of bath sites. The self-consistency cycles
are fully performed on the real frequency axis and expressed as numerical
stable matrix operations. The same impurity solver has been used on Ligand
Field and finite size cluster calculations and is capable of treating involved
Hamiltonians including the full rotational invariant Coulomb interaction,
spin-orbit coupling and low symmetry crystal-fields. The proposed method allows
for the calculation of a variety of correlation functions at little extra cost.


title: Associative Memories Based on Multiple-Valued Sparse Clustered Networks

abstract:
  Associative memories are structures that store data patterns and retrieve
them given partial inputs. Sparse Clustered Networks (SCNs) are
recently-introduced binary-weighted associative memories that significantly
improve the storage and retrieval capabilities over the prior state-of-the art.
However, deleting or updating the data patterns result in a significant
increase in the data retrieval error probability. In this paper, we propose an
algorithm to address this problem by incorporating multiple-valued weights for
the interconnections used in the network. The proposed algorithm lowers the
error rate by an order of magnitude for our sample network with 60% deleted
contents. We then investigate the advantages of the proposed algorithm for
hardware implementations.


title:
Large Deviations for stationary probabilities of a family of continuous
  time Markov chains via Aubry-Mather theory

abstract:
  We consider a family of continuous time symmetric random walks indexed by
$k\in \mathbb{N}$, $\{X_k(t),\,t\geq 0\}$. For each $k\in \mathbb{N}$ the
matching random walk take values in the finite set of states
$\Gamma_k=\frac{1}{k}(\mathbb{Z}/k\mathbb{Z})$ which is a subset of the unitary
circle. The stationary probability for such process converges to the uniform
distribution on the circle, when $k\to \infty$.
  We disturb the system considering a fixed $C^2$ potential $V: \mathbb{S}^1
\to \mathbb{R}$ and we will denote by $V_k$ the restriction of $V$ to
$\Gamma_k$. Then, we define a non-stochastic semigroup generated by the matrix
$k\,\, L_k + k\,\, V_k$, where $k\,\, L_k $ is the infinifesimal generator of
$\{X_k(t),\,t\geq 0\}$. From the continuous time Perron's Theorem one can
normalized such semigroup, and, then we get another stochastic semigroup which
generates a continuous time Markov Chain taking values on $\Gamma_k$. The
stationary probability vector for such Markov Chain is denoted by $\pi_{k,V}$.
We assume that the maximum of $V$ is attained in a unique point $x_0$ of
$\mathbb{S}^1$, and from this will follow that $\pi_{k,V}\to \delta_{x_0}$. Our
main goal is to analyze the large deviation principle for the family
$\pi_{k,V}$, when $k \to\infty$. The deviation function $I^V$, which is defined
on $ \mathbb{S}^1$, will be obtained from a procedure based on fixed points of
the Lax-Oleinik operator and Aubry-Mather theory.


title: Measures of disturbance and incompatibility for quantum measurements

abstract:
  We propose a class of incompatibility measures for quantum observables based
on quantifying the effect of a measurement of one observable on the statistics
of the outcomes of another. Specifically, for a pair of observables $A$ and $B$
with purely discrete spectra, we compare the following two probability
distributions: one resulting from a measurement of $A$ followed by a
measurement of $B$ on a given state, and the other obtained from a measurement
of $B$ alone on the same state. We show that maximizing the distance between
these two distributions over all states yields a valid measure of the
incompatibility of observables $A$ and $B$, which is zero if and only if they
commute and is strictly greater than zero (and less than or equal to one)
otherwise.
  For finite dimensional systems, we obtain a tight upper bound on the
incompatibility of any pair of observables and show that the bound is attained
when the observables are totally non-degenerate and associated with mutually
unbiased bases. In the process, we also establish an important connection
between the incompatibility of a pair of observables and the maximal
disturbances due to their measurements. Finally, we indicate how these measures
of incompatibility and disturbance can be extended to the more general class of
non-projective measurements. In particular, we obtain a non-trivial upper bound
on the incompatibility of one L\"uders instrument with another.


title: New equidistribution estimates of Zhang type

abstract:
  We prove distribution estimates for primes in arithmetic progressions to
large smooth squarefree moduli, with respect to congruence classes obeying
Chinese Remainder Theorem conditions, obtaining an exponent of distribution
$\frac{1}{2} + \frac{7}{300}$.


title:
A Study on the Optimal Implementation of Statistical Multiplexing in DVB
  Distribution Systems

abstract:
  The paper presents an overview of the main methods used to improve the
efficiency of DVB systems, based on multiplexing, through a study on the impact
of the multiplexing methods used in DVB, having as a final goal a better usage
of the data capacity and the possibility to insert new services into the
original DVB Transport Stream. This study revealed that not all DVB providers
are using statistical multiplexing. Based on this study, we were able to
propose a method to improve the original DVB stream, originated from DVB-S or
DVB-T providers. This method is proposing the detection of null packets,
removal and reinserting a new service, with a VBR content. The method developed
in this research can be implemented even in optimized statistical multiplexing
systems, due to a residual use of null packets for data rate adjustment. There
is no need to have access in the original stream multiplexer, since the method
allows the implementation on the fly, near to the end user. The proposed method
is proposed to be applied in DVB-S to DVB-C translation, using the computing
power of a PC or in a FPGA implementation.


title:
Observation of quantum interference in the plasmonic Hong-Ou-Mandel
  effect

abstract:
  We report direct evidence of the bosonic nature of surface plasmon polaritons
(SPPs) in a scattering-based beamsplitter. A parametric down-conversion source
is used to produce two indistinguishable photons, each of which is converted
into a SPP on a metal-stripe waveguide and then made to interact through a
semi-transparent Bragg mirror. In this plasmonic analog of the Hong-Ou-Mandel
experiment, we measure a coincidence dip with a visibility of 72%, a key
signature that SPPs are bosons and that quantum interference is clearly
involved.


title:
Accuracy tests of radiation schemes used in hot Jupiter global
  circulation models

abstract:
  The treatment of radiation transport in global circulation models (GCMs) is
crucial to correctly describe Earth and exoplanet atmospheric dynamics
processes. The two-stream approximation and correlated-k method are currently
state-of-the-art approximations applied in both Earth and hot Jupiter GCM
radiation schemes to facilitate rapid calculation of fluxes and heating rates.
Their accuracy have been tested extensively for Earth-like conditions, but
verification of the methods' applicability to hot Jupiter-like conditions is
lacking in the literature. We are adapting the UK Met Office GCM, the Unified
Model (UM), for the study of hot Jupiters, and present in this work the
adaptation of the Edwards-Slingo radiation scheme based on the two-stream
approximation and the correlated-k method. We discuss the calculation of
absorption coefficients from high temperature line lists and highlight the
large uncertainty in the pressure-broadened line widths. We compare fluxes and
heating rates obtained with our adapted scheme to more accurate discrete
ordinate (DO) line-by-line (LbL) calculations ignoring scattering effects. We
find that, in most cases, errors stay below 10 % for both heating rates and
fluxes using ~ 10 k-coefficients in each band and a diffusivity factor D =
1.66. The two-stream approximation and the correlated-k method both contribute
non-negligibly to the total error. We also find that using band-averaged
absorption coefficients, which have previously been used in
radiative-hydrodynamical simulations of a hot Jupiter, may yield errors of ~
100 %, and should thus be used with caution.


title: Embeddability in the 3-sphere is decidable

abstract:
  We show that the following algorithmic problem is decidable: given a
$2$-dimensional simplicial complex, can it be embedded (topologically, or
equivalently, piecewise linearly) in $\mathbf{R}^3$? By a known reduction, it
suffices to decide the embeddability of a given triangulated 3-manifold $X$
into the 3-sphere $S^3$. The main step, which allows us to simplify $X$ and
recurse, is in proving that if $X$ can be embedded in $S^3$, then there is also
an embedding in which $X$ has a short meridian, i.e., an essential curve in the
boundary of $X$ bounding a disk in $S^3\setminus X$ with length bounded by a
computable function of the number of tetrahedra of $X$.


title:
Nonlinear photoacoustic wavefront shaping (PAWS) for single
  speckle-grain optical focusing in scattering media

abstract:
  Non-invasively focusing light into strongly scattering media, such as
biological tissue, is highly desirable but challenging. Recently, wavefront
shaping technologies guided by ultrasonic encoding or photoacoustic sensing
have been developed to address this limitation. So far, these methods provide
only acoustic diffraction-limited optical focusing. Here, we introduce
nonlinear photoacoustic wavefront shaping (PAWS), which achieves optical
diffraction-limited (i.e. single-speckle-grain) focusing in scattering media.
We develop an efficient dual-pulse excitation approach to generate strong
nonlinear photoacoustic (PA) signals based on the Grueneisen memory effect.
These nonlinear PA signals are used as feedback to guide iterative wavefront
optimization. By maximizing the amplitude of the nonlinear PA signal, light is
effectively focused to a single optical speckle grain. Experimental results
demonstrate a clear optical focus on the scale of 5-7 micrometers, which is ~10
times smaller than the acoustic focus in linear dimension, with an enhancement
factor of ~6000 in peak fluence. This technology has the potential to provide
highly confined strong optical focus deep in tissue for microsurgery of
Parkinson's disease and epilepsy or single-neuron imaging and optogenetic
activation.


title: A real space auxiliary field approach to the BCS-BEC crossover

abstract:
  The BCS to BEC crossover in attractive Fermi systems is a prototype of weak
to strong coupling evolution in many body physics. While extensive numerical
results are available, and several approximate methods have been developed,
most of these schemes are unsuccessful in the presence of spatial
inhomogeneity. Such situations call for a real space approach that can handle
large spatial scales and retain the crucial thermal fluctuations. With this in
mind, we present comprehensive results of a real space auxiliary field approach
to the BCS to BEC crossover in the attractive Hubbard model in two dimensions.
The scheme reproduces the Hartree-Fock-Bogoliubov ground state, and leads to a
$T_c$ scale that agrees with quantum Monte Carlo estimates to within a few
percent. We provide results on the $T_c$, amplitude and phase fluctuations,
density of states, and the momentum resolved spectral function over the entire
interaction and temperature window. We suggest how the method generalises
successfully to the presence of disorder, trapping, and population imbalance.


title: Almost square Banach spaces

abstract:
  We single out and study a natural class of Banach spaces -- almost square
Banach spaces. In an almost square space we can find, given a finite set
$x_1,x_2,\ldots,x_N$ in the unit sphere, a unit vector $y$ such that
$\|x_i-y\|$ is almost one. These spaces have duals that are octahedral and
finite convex combinations of slices of the unit ball of an almost square space
have diameter 2. We provide several examples and characterizations of almost
square spaces. We prove that non-reflexive spaces which are M-ideals in their
biduals are almost square.
  We show that every separable space containing a copy of $c_0$ can be renormed
to be almost square. A local and a weak version of almost square spaces are
also studied.


title:
Observation of the Meissner effect with ultracold atoms in bosonic
  ladders

abstract:
  We report on the observation of the Meissner effect in bosonic flux ladders
of ultracold atoms. Using artificial gauge fields induced by laser-assisted
tunneling, we realize arrays of decoupled ladder systems that are exposed to a
uniform magnetic field. By suddenly decoupling the ladders and projecting into
isolated double wells, we are able to measure the currents on each side of the
ladder. For large coupling strengths along the rungs of the ladder, we find a
saturated maximum chiral current corresponding to a full screening of the
artificial magnetic field. For lower coupling strengths, the chiral current
decreases in good agreement with expectations of a vortex lattice phase. Our
work marks the first realization of a low-dimensional Meissner effect and,
furthermore, it opens the path to exploring interacting particles in low
dimensions exposed to a uniform magnetic field.


title: Lifshitz Quartic Quasitopological Black Holes

abstract:
  In this paper we shall elucidate some of the effects of the quartic
quasitopological term for Lifshitz-symmetric black holes. The field equations
of this theory are difficult to solve exactly; here we will use numerical
solutions both to verify previous exact solutions for quartic quasitopological
AdS black holes as well as to examine new quasitopological Lifshitz-symmetric
black hole solutions, in order to determine the effect of the quartic coupling
parameter on the black hole's thermodynamic behavior. We shall find that the
quartic parameter controls solutions very similarly to the cubic parameter,
allowing for the construction of a theory with another free parameter which may
find meaning in the phase transition behaviour of a gauge/gravity context.


title: Atomic form factor for twisted vortex photons interacting with atoms

abstract:
  The relatively new atomic form factor for twisted (vortex) beams, which carry
orbital angular momentum (OAM), is considered and compared to the conventional
atomic form factor for plane wave beams that carry only spin angular momentum
(SAM). Since the vortex symmetry of a twisted photon is more complex that that
of a plane-wave, evaluation of the atomic form factor is also more complex for
twisted photons. On the other hand, the twisted photon has additional
parameters, including the OAM quantum number, $\ell$, the nodal radial number,
$p$, and the Rayleigh range, $z_R$ that determines the cone angle of the
vortex. This Rayleigh range may be used as a variable parameter to control, in
new ways, the interaction of twisted photons with matter. Here we address: i)
normalization of the vortex atomic form factor, ii) displacement of target
atoms away from the center of the beam vortex, and iii) formulation of
transition probabilities for a variety of photon-atom processes. We attend to
features related to new experiments that can test the range of validity and
accuracy of calculations of these variations of the atomic form factor. Using
the absolute square of the form factor for vortex beams, we introduce a vortex
factor that can be directly measured.


title: Markov bridges: SDE representation

abstract:
  Let $X$ be a Markov process taking values in $\mathbf{E}$ with continuous
paths and transition function $(P_{s,t})$. Given a measure $\mu$ on
$(\mathbf{E}, \mathscr{E})$, a Markov bridge starting at $(s,\varepsilon_x)$
and ending at $(T^*,\mu)$ for $T^* <\infty$ has the law of the original process
starting at $x$ at time $s$ and conditioned to have law $\mu$ at time $T^*$. We
will consider two types of conditioning: a) {\em weak conditioning} when $\mu$
is absolutely continuous with respect to $P_{s,t}(x,\cdot)$ and b) {\em strong
conditioning} when $\mu=\varepsilon_z$ for some $z \in \mathbf{E}$. The main
result of this paper is the representation of a Markov bridge as a solution to
a stochastic differential equation (SDE) driven by a Brownian motion in a
diffusion setting. Under mild conditions on the transition density of the
underlying diffusion process we establish the existence and uniqueness of weak
and strong solutions of this SDE.


title:
An interpretive conjecture for physics beyond the standard models:
  generalized complementarity

abstract:
  Our interpretive conjecture is inspired by the epistemology due to Ferdinand
Gonseth (1890-1975) who interpreted complementarity as the relationship between
profound and apparent reality horizons. It consists, on the one hand, on
enlarging the scope of quantum theory to the most profound reality horizon,
namely a triply quantum theory of gravitation that would be able to take into
account simultaneously as elementary quanta the Planck's constant, the Planck's
space-time area and the Boltzmann constant, and, on the other hand, on
interpreting in terms of generalized complementarity three doubly quantum
schemata taking into account by pairs, these three elementary quanta and form
the apparent reality horizon.


title: New Stellar Models - Boon or Bane?

abstract:
  The impact of new stellar evolution models with rotation on the predictions
of population synthesis models is discussed. Massive rotating stars have larger
convective cores than their non-rotating counterparts, and their outer layers
are chemically enriched due to increased mixing. Together, these two effects
lead to hotter and more luminous stars, in particular during later evolutionary
phases. As a result, stellar populations containing massive stars are predicted
to become more luminous for a given mass and to emit more ionizing photons.
Depending on the assumed rotation velocity, rotation causes profound changes in
the properties of young stellar populations. These changes are most noticeable
at later evolutionary phases and at shorter wavelengths of the spectral energy
distribution. Most strikingly, the Lyman continuum luminosity increases by up
to a factor of five in O- and Wolf-Rayet stars. Care is required when comparing
these models to observations, and some fine-tuning of the models is still
required before recalibrations of star-formation indicators should be
attempted.


title: Generating function of the tilings of Aztec rectangle with holes

abstract:
  We consider a generating function of the domino tilings of an Aztec rectangle
with several boundary unit squares removed. Our generating function involves
two statistics: the rank of the tiling and half number of vertical dominoes as
in the Aztec diamond theorem by Elkies, Kuperberg, Larsen and Propp. In
addition, our work deduces a combinatorial explanation for an interesting
connection between the number of lozenge tilings of a semihexagon and the
number of domino tilings of an Aztec rectangle.


title: A Characterisation of Strong Integer Additive Set-Indexers of Graphs

abstract:
  An integer additive set-indexer is defined as an injective function
$f:V(G)\rightarrow 2^{\mathbb{N}_0}$ such that the induced function $g_f:E(G)
\rightarrow 2^{\mathbb{N}_0}$ defined by $g_f (uv) = f(u)+ f(v)$ is also
injective, where $f(u)+f(v)$ is the sumset of $f(u)$ and $f(v)$. If
$g_f(uv)=k~\forall~uv\in E(G)$, then $f$ is said to be a $k$-uniform integer
additive set-indexers. An integer additive set-indexer $f$ is said to be a
strong integer additive set-indexer if $|g_f(uv)|=|f(u)|.|f(v)|~\forall ~ uv\in
E(G)$. We already have some characteristics of the graphs which admit strong
integer additive set-indexers. In this paper, we study the characteristics of
certain graph classes, graph operations and graph products that admit strong
integer additive set-indexers.


title: Exploring the role of the charm quark in the $\Delta I=1/2$ rule

abstract:
  We study the dependence on the charm quark mass of the leading-order
low-energy constants of the $\Delta S=1$ effective Hamiltonian, with the aim of
elucidating the role of the charm mass scale in the $\Delta I=1/2$ rule for
$K\to\pi\pi$ decay. To that purpose, finite-volume Chiral Perturbation Theory
predictions are matched to QCD simulations, performed in the quenched
approximation with overlap fermions and $m_u=m_d=m_s$. Light quark masses range
between a few MeV up to around one third of the physical strange mass, while
charm masses range between $m_u$ and a few hundred MeV. Novel variance
reduction techniques are used to obtain a signal for penguin contractions in
correlation functions involving four-fermion operators. The important role
played by the subtractions required to construct renormalised amplitudes for
$m_c \neq m_u$ is discussed in detail. We find evidence that the moderate
enhancement of the $\Delta I=1/2$ amplitude previously found in the GIM limit
$m_c=m_u$ increases only slightly as $m_c$ abandons the light quark regime.
Hints of a stronger enhancement for even higher values of $m_c$ are also found,
but their confirmation requires a better understanding of the subtraction
terms.


title: Supersymmetry Breaking and the Cosmological Constant

abstract:
  I review three attempts to explain the small value of the cosmological
constant, and their connection to SUSY breaking. They are The String Landscape,
Supersymmetric Large Extra Dimensions (SLED), and the Holographic Space-time
Formalism invented by Fischler and myself.


title:
Sharp Estimates for Norms of Functions from Conjugate Classes in Metrics
  C and L

abstract:
  Sharp estimates for C - and L - norms of functions that are conjugate with
functions from the classes W^rH_\omega of periodic functions having prescribed
concave majorant of moduli of continuity, as well as sharp estimates for the
differences of such functions are obtained.


title: A new perspective on least squares under convex constraint

abstract:
  Consider the problem of estimating the mean of a Gaussian random vector when
the mean vector is assumed to be in a given convex set. The most natural
solution is to take the Euclidean projection of the data vector on to this
convex set; in other words, performing "least squares under a convex
constraint." Many problems in modern statistics and statistical signal
processing theory are special cases of this general situation. Examples include
the lasso and other high-dimensional regression techniques, function estimation
problems, matrix estimation and completion, shape-restricted regression,
constrained denoising, linear inverse problems, etc. This paper presents three
general results about this problem, namely, (a) an exact computation of the
main term in the estimation error by relating it to expected maxima of Gaussian
processes (existing results only give upper bounds), (b) a theorem showing that
the least squares estimator is always admissible up to a universal constant in
any problem of the above kind and (c) a counterexample showing that least
squares estimator may not always be minimax rate-optimal. The result from part
(a) is then used to compute the error of the least squares estimator in two
examples of contemporary interest.


title: Variance reduction with practical all-to-all lattice propagators

abstract:
  We discuss all-to-all quark propagator techniques in two (related) contexts
within Lattice QCD: the computation of closed quark propagators, and
applications to the so-called "eye diagrams" appearing in the computation of
non-leptonic kaon decay amplitudes. Combinations of low-mode averaging and
diluted stochastic volume sources that yield optimal signal-to-noise ratios for
the latter problem are developed. We also apply a recently proposed probing
algorithm to compute directly the diagonal of the inverse Dirac operator, and
compare its performance with that of stochastic methods. At fixed computational
cost the two procedures yield comparable signal-to-noise ratios, but probing
has practical advantages which make it a promising tool for a wide range of
applications in Lattice QCD.


title:
Large-Scale Asymmetries in the Transitional Disks of SAO 206462 and SR
  21

abstract:
  We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
in the dust continuum (690 GHz, 0.45 mm) and 12CO J=6-5 spectral line emission,
of the transitional disks surrounding the stars SAO 206462 and SR 21. These
ALMA observations resolve the dust-depleted disk cavities and extended gaseous
disks, revealing large-scale asymmetries in the dust emission of both disks. We
modeled these disks structures with a ring and an azimuthal gaussian, where the
azimuthal gaussian is motivated by the steady-state vortex solution from Lyra &
Lin (2013). Compared to recent observations of HD 142527, Oph IRS 48, and LkHa
330, these are low-contrast (< 2) asymmetries. Nevertheless, a ring alone is
not a good fit, and the addition of a vortex prescription describes these data
much better. The asymmetric component encompasses 15% and 28% of the total disk
emission in SAO 206462 and SR 21 respectively, which corresponds to a lower
limit of 2 MJup of material within the asymmetry for both disks. Although the
contrast in the dust asymmetry is low, we find that the turbulent velocity
inside it must be large (~20% of the sound speed) in order to drive these
azimuthally wide and radially narrow vortex-like structures. We obtain
residuals from the ring and vortex fitting that are still significant, tracing
non-axisymmetric emission in both disks. We compared these submillimeter
observations with recently published H-band scattered light observations. For
SR 21 the scattered light emission is distributed quite differently from the
submillimeter continuum emission, while for SAO 206462 the submillimeter
residuals are suggestive of spiral-like structure similar to the near-IR
emission.


title:
Evidence of resonant mode coupling and the relationship between low and
  high frequencies in a rapidly rotating A star

abstract:
  In the theory of resonant mode coupling, the parent and child modes are
directly related in frequency and phase. The oscillations present in the fast
rotating Delta Scuti star KIC 8054146 allow us to test the most general and
generic aspects of such a theory. The only direct way to separate the parent
and coupled (child) modes is to examine the correlations in amplitude
variability between the different frequencies. For the dominant family of
related frequencies, only a single mode and a triplet are the origins of nine
dominant frequency peaks ranging from 2.93 to 66.30 cycles per day (as well as
dozens of small-amplitude combination modes and a predicted and detected third
high-frequency triplet). The mode-coupling model correctly predicts the large
amplitude variations of the coupled modes as a product of the amplitudes of the
parent modes, while the phase changes are also correctly modeled. This differs
from the behavior of 'normal' combination frequencies in that the amplitudes
are three orders of magnitude larger and may exceed even the amplitudes of the
parent modes. We show that two dominant low frequencies at 5.86 and 2.93 cycles
per day in the gravity-mode region are not harmonics of each other, and their
properties follow those of the almost equidistant high-frequency triplet. We
note that the previously puzzling situation of finding two strong peaks in the
low-frequency region related by nearly a factor of two in frequency has been
seen in other Delta Scuti stars as well.


title: Essential enhancements revisited

abstract:
  In 1991 Aizenman and Grimmett claimed that any `essential enhancement' of
site or bond percolation on a lattice lowers the critical probability, an
important result with many implications, such as strict inequalities between
critical probabilities on suitable pairs of lattices. Their proof has two
parts, one probabilistic and one combinatorial. In this paper we point out that
a key combinatorial lemma, for which they provide only a figure as proof, is
false. We prove an alternative form of the lemma, and thus the enhancement
result, in the special cases of site percolation on the square, triangular and
cubic lattices, and for bond percolation on $Z^d$, $d\ge 2$. The general case
remains open, even for site percolation on $Z^d$, $d\ge 4$.


title:
Results on identified particle production in pp, p-Pb and Pb-Pb
  collisions measured with ALICE at the LHC

abstract:
  Using the unique capabilities of the ALICE detectors for particle
identification, different measurements have been performed to study the
properties of the hot and dense matter created in the Pb-Pb collisions at
sqrt(sNN)= 2.76 TeV. The analysis of the p-Pb data at sqrt(sNN) = 5.02 TeV
reveals that the suppression of high pt hadrons observed in heavy nuclei
collisions can not be explained as due to initial state effects. The systems
created in the p-Pb collisions do not show evidence of jet quenching but,
surprisingly, exhibit characteristics of flow. In this paper a review of the
main results on identified particle production measured in different colliding
systems is presented, data are also compared to models.


title: Cognitive Aging as Interplay between Hebbian Learning and Criticality

abstract:
  Cognitive ageing seems to be a story of global degradation. As one ages there
are a number of physical, chemical and biological changes that take place.
Therefore it is logical to assume that the brain is no exception to this
phenomenon. The principle purpose of this project is to use models of neural
dynamics and learning based on the underlying principle of self-organised
criticality, to account for the age related cognitive effects. In this regard
learning in neural networks can serve as a model for the acquisition of skills
and knowledge in early development stages i.e. the ageing process and
criticality in the network serves as the optimum state of cognitive abilities.
Possible candidate mechanisms for ageing in a neural network are loss of
connectivity and neurons, increase in the level of noise, reduction in white
matter or more interestingly longer learning history and the competition among
several optimization objectives. In this paper we are primarily interested in
the affect of the longer learning history on memory and thus the optimality in
the brain. Hence it is hypothesized that prolonged learning in the form of
associative memory patterns can destroy the state of criticality in the
network. We base our model on Tsodyks and Markrams [49] model of dynamic
synapses, in the process to explore the effect of combining standard Hebbian
learning with the phenomenon of Self-organised criticality. The project mainly
consists of evaluations and simulations of networks of integrate and
fire-neurons that have been subjected to various combinations of neural-level
ageing effects, with the aim of establishing the primary hypothesis and
understanding the decline of cognitive abilities due to ageing, using one of
its important characteristics, a longer learning history.


title: On the existence of the $\it NN$-decoupled dibaryon $d^\ast_1$(1956)

abstract:
  We present strong experimental evidence for the existence of a nonstrange
$\it NN$-decoupled dibaryon with a mass of about 1956 MeV stable against strong
decay, which is a very likely candidate for long-sought multiquark hadrons with
the baryon number B=2. We start by presenting the first evidence for the
existence of this dibaryon called $d^{\ast }_{1}$(1956), that was found in the
energy spectrum of coincident photons emitted at $\pm 90^0$ from the reaction
$pp \to pp \gamma\gamma$ at an energy of 216 MeV measured at JINR. We then show
its signatures found in several experimental energy spectra of single photons
and invariant mass spectra of photon pairs from photon production processes
induced by nucleon-nucleon and nucleon-nucleus collisions at intermediate
energies.


title:
The nature of the Roberge-Weiss transition in $N_f=2$ QCD with Wilson
  fermions

abstract:
  At imaginary values of the quark chemical potential $\mu$, Quantum
Chromodynamics shows an interesting phase structure due to an exact center, or
Roberge-Weiss (RW), symmetry. This can be used to constrain QCD at real $\mu$,
where the sign problem prevents Monte Carlo simulations of the lattice theory.
In previous studies of this region with staggered fermions it was found that
the RW endpoint, where the center transition changes from first-order to a
crossover, depends non-trivially on the quark mass: for high and low masses, it
is a triple point connecting to the deconfinement and chiral transitions,
respectively, changing to a second-order endpoint for intermediate mass values.
These parameter regions are separated by tricritical points. Here we present a
confirmation of these findings using Wilson fermions on $N_\tau=4$ lattices. In
addition, our results provide a successful quantitative check for a heavy quark
effective lattice theory at finite density.


title: Varieties of Picard rank one as components of ample divisors

abstract:
  Let $\mathcal{V}$ be an integral normal complex projective variety of
dimension $n\geq 3$ and denote by $\mathcal{L}$ an ample line bundle on
$\mathcal{V}$. By imposing that the linear system $|\mathcal{L}|$ contains an
element $A=A_{1}+...+A_{r}, r\geq 1$, where all the $A_{i}$'s are distinct
effective Cartier divisors with Pic$(A_i)=\mathbb{Z}$, we show that such a
$\mathcal{V}$ is as special as the components $A_i$ of $A\in |\mathcal{L}|$.
After making a list of some consequences about the positivity of the components
$A_i$, we characterize pairs $(\mathcal{V}, \mathcal{L})$ as above when either
$A_1\cong\mathbb{P}^{n-1}$ and Pic$(A_j)=\mathbb{Z}$ for $j=2,...,r,$ or
$\mathcal{V}$ is smooth and each $A_i$ is a variety of small degree with
respect to $[H_i]_{A_i}$, where $[H_i]_{A_i}$ is the restriction to $A_i$ of a
suitable line bundle $H_i$ on $\mathcal{V}$.


title: Exchange-induced crystallization of soft core bosons

abstract:
  We study the phase diagram of a two-dimensional assembly of bosons
interacting via a soft core repulsive pair potential of varying strength, and
compare it to that of the equivalent system in which particles are regarded as
distinguishable. We show that quantum-mechanical exchanges stabilize a "cluster
crystal" phase in a wider region of parameter space than predicted by
calculations in which exchanges are neglected. This physical effect is
diametrically opposite to that which takes place in hard core Bose systems such
as $^4$He, wherein exchanges strengthen the fluid phase. It is underlain in the
cluster crystal phase of soft core bosons by the free energy gain associated to
the formation of local Bose-Einstein condensates.


title: The Three-body problem and the shape sphere

abstract:
  [This is an expository article. I have submitted it to the American
Mathematical Monthly.] The three-body problem defines a dynamics on the space
of triangles in the plane. The shape sphere is the moduli space of oriented
similarity classes of planar triangles and lies inside shape space, a Euclidean
3-space parametrizing oriented congruence classes of triangles. We derive and
investigate the geometry and dynamics induced on these spaces by the three-body
problem. We present two theorems concerning the three-body problem whose
discovery was made through the shape space perspective


title: Quantum Control of Molecular Gas Hydrodynamics

abstract:
  We demonstrate that strong impulsive gas heating or heating suppression at
standard temperature and pressure can occur from coherent rotational excitation
or de-excitation of molecular gases using a sequence of non-ionizing laser
pulses. For the case of excitation, subsequent collisional decoherence of the
ensemble leads to gas heating significantly exceeding that from plasma
absorption under the same laser focusing conditions. In both cases, the
macroscopic hydrodynamics of the gas can be finely controlled with ~40 fs
temporal sensitivity.


title:
Monotone quantities involving a weighted $\sigma_k$ integral along
  inverse curvature flows

abstract:
  We give a family of monotone quantities along smooth solutions to the inverse
curvature flows in Euclidean spaces. We also derive a related geometric
inequality for closed hypersurfaces with positive k-th mean curvature.


title:
On the theoretic and practical merits of the banding estimator for large
  covariance matrices

abstract:
  This paper considers the banding estimator proposed in Bickel and Levina
(2008) for estimation of large covariance matrices. We prove that the banding
estimator achieves rate-optimality under the operator norm, for a class of
approximately banded covariance matrices, improving the existing results in
Bickel and Levina (2008). In addition, we propose a Stein's unbiased risk
estimate (Sure)-type approach for selecting the bandwidth for the banding
estimator. Simulations indicate that the Sure-tuned banding estimator
outperforms competing estimators.


title: The sign of the logistic regression coefficient

abstract:
  Let Y be a binary random variable and X a scalar. Let $\hat\beta$ be the
maximum likelihood estimate of the slope in a logistic regression of Y on X
with intercept. Further let $\bar x_0$ and $\bar x_1$ be the average of sample
x values for cases with y=0 and y=1, respectively. Then under a condition that
rules out separable predictors, we show that sign($\hat\beta$) = sign($\bar
x_1-\bar x_0$). More generally, if $x_i$ are vector valued then we show that
$\hat\beta=0$ if and only if $\bar x_1=\bar x_0$. This holds for logistic
regression and also for more general binary regressions with inverse link
functions satisfying a log-concavity condition. Finally, when $\bar x_1\ne \bar
x_0$ then the angle between $\hat\beta$ and $\bar x_1-\bar x_0$ is less than
ninety degrees in binary regressions satisfying the log-concavity condition and
the separation condition, when the design matrix has full rank.


title: Near-IR Direct Detection of Water Vapor in Tau Boo b

abstract:
  We use high dynamic range, high-resolution L-band spectroscopy to measure the
radial velocity variations of the hot Jupiter in the tau Bootis planetary
system. The detection of an exoplanet by the shift in the stellar spectrum
alone provides a measure of the planet's minimum mass, with the true mass
degenerate with the unknown orbital inclination. Treating the tau Boo system as
a high flux ratio double-lined spectroscopic binary permits the direct
measurement of the planet's true mass as well as its atmospheric properties.
After removing telluric absorption and cross-correlating with a model planetary
spectrum dominated by water opacity, we measure a 6-sigma detection of the
planet at K_p = 111 +- 5 km/s, with a 1-sigma upper limit on the spectroscopic
flux ratio of 10^-4. This radial velocity leads to a planetary orbital
inclination of i = 45+3-4degrees and a mass of M_P = 5.90+0.35-0.20 M_ Jup. We
report the first detection of water vapor in the atmosphere of a non-transiting
hot Jupiter, tau Boo b.


title:
Generalized Moment Method for Gap Estimation and Quantum Monte Carlo
  Level Spectroscopy

abstract:
  We formulate a convergent sequence for the energy gap estimation in the
worldline quantum Monte Carlo method. The ambiguity left in the conventional
gap calculation for quantum systems is eliminated. Our estimation will be
unbiased in the low-temperature limit and also the error bar is reliably
estimated. The level spectroscopy from quantum Monte Carlo data is developed as
an application of the unbiased gap estimation. From the spectral analysis, we
precisely determine the Kosterlitz-Thouless quantum phase-transition point of
the spin-Peierls model. It is stablished that the quantum phonon with a finite
frequency is essential to the critical theory governed by the antiadiabatic
limit, i.e., the $k=1$ SU(2) Wess-Zumino-Witten model.


title: A simple mechanism for the anti-glitch observed in magnetar 1E 2259+586

abstract:
  In this short communication we present a simple internal mechanism that
accounts for the recently observed anti-glitch in magnetar 1E 2259+586. We
propose that the decay of an internal toroidal magnetic field component would
de-stabilize an originally stable prolate star configuration. Then, the
subsequent rearrangement of the stellar structure would give rise to a "more
spherical" configuration, resulting in a sudden spin-down of the whole star. We
present here some order of magnitude calculation to give confidence to this
scenario, using the simplest analytical stellar model and let more detailed
calculations for a more technical future paper.