title: Enhancements of weak gauge boson scattering processes at the CERN LHC

abstract:
  Current CERN Large Hadron Collider data on the 126 GeV standard model-like
Higgs boson suggest the possibility of larger Higgs boson couplings with the
weak gauge bosons, $g_{hVV}$, than those in the standard model. We use the
Georgi-Machacek model as an explicit model to realize such a scenario. We find
that the $g_{hVV}$ couplings can be larger than the standard model value by a
factor of about 1.3 maximally in the parameter region consistent with the
current Higgs boson search data and allowed by various other constraints. We
then show how the modified $g_{hVV}$ couplings lead to enhancements in various
weak boson scattering processes. This can be clearly observed as excesses in
the transverse mass distributions at around 126 GeV and also the mass of heavy
Higgs bosons.


title:
Screening-induced negative differential conductance in the Franck-Condon
  blockade regime

abstract:
  Screening effects in nanoscale junctions with strong electron-phonon coupling
open new physical scenarios. We propose an accurate many-body approach to deal
with the simultaneous occurrence of the Franck-Condon blockade and the
screening-induced enhancement of the polaron mobility. We derive a transparent
analytic expression for the electrical current: transient and steady-state
features are directly interpreted and explained. Moreover, the interplay
between phononic and electronic excitations gives rise to a novel mechanism of
negative differential conductance. Experimental setup to observe this
phenomenon are discussed.


title:
Review of nuclear magnetic resonance studies on iron-based
  superconductors

abstract:
  The newly discovered iron-based superconductors have triggered renewed
enormous research interest in the condensed matter physics community. Nuclear
magnetic resonance (NMR) is a low-energy local probe for studying strongly
correlated electrons, and particularly important for high-$T_{\rm C}$
superconductors. In this paper, we review NMR studies on the structural
transition, antiferromagnetic order, spin fluctuations, and superconducting
properties of several iron-based high-$T_{\rm C}$ superconductors, including
LaFeAsO$_{1-x}$F$_x$, LaFeAsO$_{1-x}$, BaFe$_2$As$_2$,
Ba$_{1-x}$K$_x$Fe$_2$As$_2$, Ca$_{0.23}$Na$_{0.67}$Fe$_2$As$_2$,
BaFe$_2$(As$_{1-x}$P$_x$)$_2$, Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$,
Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, Li$_{1+x}$FeAs, LiFe$_{1-x}$Co$_x$As, NaFeAs,
NaFe$_{1-x}$Co$_x$As, K$_y$Fe$_{2-x}$Se$_2$, and (Tl,Rb)$_y$Fe$_{2-x}$Se$_2$.


title: Nucleon decay via dimension 6 operators in anomalous U(1)_A SUSY GUT

abstract:
  Nucleon lifetimes for various decay modes via dimension 6 operators are
calculated in the anomalous $U(1)_A$ GUT scenario, in which the unification
scale $\Lambda_u$ becomes smaller than the usual supersymmetric (SUSY)
unification scale $\Lambda_G=2\times 10^{16}$ GeV in general. Since the
predicted lifetime $\tau(p\rightarrow \pi^0+e^c)$ becomes around the
experimental lower bound though it is strongly dependent on the explicit
models, the discovery of the nucleon decay in near future can be expected. We
explain why the two ratios $R_1\equiv\frac{\Gamma_{n \rightarrow \pi^0 +
\nu^c}}{\Gamma_{p \rightarrow \pi^0 + e^c}}$ and $R_2\equiv\frac{\Gamma_{p
\rightarrow K^0 + \mu^c}}{\Gamma_{p \rightarrow \pi^0 + e^c}}$ are important in
identifying grand unification group and we show that three anomalous $U(1)_A$
SUSY GUT models with $SU(5)$, $SO(10)$ and $E_6$ grand unification group can be
identified by measuring the two ratios. If $R_1$ is larger than $0.4$, the
grand unification group is not $SU(5)$, and moreover if $R_2$ is larger than
$0.3$, the grand unification group is implied to be $E_6$.


title:
Effects of electronic correlations and magnetic field on a molecular
  ring out of equilibrium

abstract:
  We study effects of electron-electron interactions on the steady-state
characteristics of a hexagonal molecular ring in a magnetic field, as a model
for a benzene molecular junction. The system is driven out of equilibrium by
applying a bias voltage across two metallic leads. We employ a model
Hamiltonian approach to evaluate the effects of on-site as well as
nearest-neighbour density-density type interactions in a physically relevant
parameter regime. Results for the steady-state current, charge density and
magnetization in three different junction setups (para, meta and ortho) are
presented. Our findings indicate that interactions beyond the mean-field level
renormalize voltage thresholds as well as current plateaus. Electron-electron
interactions lead to substantial charge redistribution as compared to the
mean-field results. We identify a strong response of the circular current on
the electronic structure of the metallic leads. Our results are obtained by
steady-state Cluster Perturbation Theory, a systematically improvable
approximation to study interacting molecular junctions out of equilibrium, even
in magnetic fields. Within this framework general expressions for the current,
charge density and magnetization in the steady-state are derived. The method is
flexible and fast and can straight-forwardly be applied to effective models as
obtained from ab-initio calculations.


title: Breathers on Quantized Superfluid Vortices

abstract:
  We consider the propagation of breathers along a quantised superfluid vortex.
Using the correspondence between the local induction approximation (LIA) and
the nonlinear Schr\"odinger equation, we identify a set of initial conditions
corresponding to breather solutions of vortex motion governed by the LIA. These
initial conditions, which give rise to a long-wavelength modulational
instability, result in the emergence of large amplitude perturbations that are
localised in both space and time. The emergent structures on the vortex
filament are analogous to loop solitons. Although the breather solutions we
study are exact solutions of the LIA equations, we demonstrate through full
numerical simulations that their key emergent attributes carry over to vortex
dynamics governed by the Biot-Savart law and to quantized vortices described by
the Gross-Pitaevskii equation. The breather excitations can lead to
self-reconnections, a mechanism that can play an important role within the
cross-over range of scales in superfluid turbulence. Moreover, the observation
of breather solutions on vortices in a field model suggests that these
solutions are expected to arise in a wide range of other physical contexts from
classical vortices to cosmological strings.


title: Anti-Levitation in the Integer Quantum Hall Systems

abstract:
  Two-dimensional electron gas in the integer quantum Hall regime is
investigated numerically by studying the dynamics of an electron hopping on a
square lattice subject to a perpendicular magnetic field and random on-site
energy with white noise distribution. Focusing on the lowest Landau band we
establish an anti-levitation scenario of the extended states: As either the
disorder strength $W$ increases or the magnetic field strength $B$ decreases,
the energies of the extended states move below the Landau energies pertaining
to a clean system. Moreover, for strong enough disorder, there is a disorder
dependent critical magnetic field $B_c(W)$ below which there are no extended
states at all. A general phase diagram in the $W-1/B$ plane is suggested with a
line separating domains of localized and delocalized states.


title: Stabilization of Linear Systems Over Gaussian Networks

abstract:
  The problem of remotely stabilizing a noisy linear time invariant plant over
a Gaussian relay network is addressed. The network is comprised of a sensor
node, a group of relay nodes and a remote controller. The sensor and the relay
nodes operate subject to an average transmit power constraint and they can
cooperate to communicate the observations of the plant's state to the remote
controller. The communication links between all nodes are modeled as Gaussian
channels. Necessary as well as sufficient conditions for mean-square
stabilization over various network topologies are derived. The sufficient
conditions are in general obtained using delay-free linear policies and the
necessary conditions are obtained using information theoretic tools. Different
settings where linear policies are optimal, asymptotically optimal (in certain
parameters of the system) and suboptimal have been identified. For the case
with noisy multi-dimensional sources controlled over scalar channels, it is
shown that linear time varying policies lead to minimum capacity requirements,
meeting the fundamental lower bound. For the case with noiseless sources and
parallel channels, non-linear policies which meet the lower bound have been
identified.


title: PotLLL: A Polynomial Time Version of LLL With Deep Insertions

abstract:
  Lattice reduction algorithms have numerous applications in number theory,
algebra, as well as in cryptanalysis. The most famous algorithm for lattice
reduction is the LLL algorithm. In polynomial time it computes a reduced basis
with provable output quality. One early improvement of the LLL algorithm was
LLL with deep insertions (DeepLLL). The output of this version of LLL has
higher quality in practice but the running time seems to explode. Weaker
variants of DeepLLL, where the insertions are restricted to blocks, behave
nicely in practice concerning the running time. However no proof of polynomial
running time is known. In this paper PotLLL, a new variant of DeepLLL with
provably polynomial running time, is presented. We compare the practical
behavior of the new algorithm to classical LLL, BKZ as well as blockwise
variants of DeepLLL regarding both the output quality and running time.


title:
Universal departure from Johnson-Nyquist relation caused by limited
  resolution

abstract:
  Exploiting the two-point measurement statistics, we propose a quantum
measurement scheme of current with limited resolution of electron counting. Our
scheme is equivalent to the full counting statistics in the long-time
measurement with the ideal resolution, but is theoretically extended to take
into account the resolution limit of actual measurement devices. Applying our
scheme to a resonant level model, we show that the limited resolution of
current measurement gives rise to a positive excess noise, which leads to a
deviation from the Johnson-Nyquist relation. The deviation exhibits universal
single-parameter scaling with the scaling variable $Q\equiv S_{\rm{}M}/S_0$,
which represents the degree of the insufficiency of the resolution. Here, $S_0$
is the intrinsic noise, and $S_{\rm{}M}$ is the positive quantity that has the
same dimension as $S_0$ and is defined solely by the measurement scheme. For
the lack of the ideal resolution, the deviation emerges for $Q<1$ as
$2\exp[-(2\pi)^2/Q]$ having an essential singularity at $Q=0$, which followed
by the square root dependence $\sqrt{Q/4\pi}$ for $Q\gg1$. Our findings offer
an explanation for the anomalous enhancement of noise temperature observed in
Johnson noise thermometry.


title:
Robust Methods for Disease-Genotype Association in Genetic Association
  Studies: Calculate P-values Using Exact Conditional Enumeration instead of
  Asymptotic Approximations

abstract:
  In genetic association studies, detecting disease-genotype associations is a
primary goal. For most diseases, the underlying genetic model is unknown, and
we study seven robust test statistics for monotone association. For a given
test statistic, there are many ways to calculate a p-value, but in genetic
association studies, calculations have predominantly been based on asymptotic
approximations or on simulated permutations. We show that when the number of
permutations tends to infinity, the permutation p-value approaches the exact
conditional enumeration p-value, and further that calculating the latter
p-value is much more efficient than performing simulated permutations. We then
answer two research questions. (i) Which of the test statistics under study are
the most powerful for monotone genetic models? (ii) Based on test size, power,
and computational considerations, should asymptotic approximations or exact
conditional enumeration be used for calculating p-values? We have studied
case-control sample sizes with 500-5000 cases and 500-15000 controls, and
significance levels from 5e-8 to 0.05, thus our results are applicable to
genetic association studies with only one genetic marker under study,
intermediate follow-up studies, and genome wide association studies. We find
that if all monotone genetic models are of interest, the best performance is
achieved for a test statistics based on the maximum over a range of
Cochrane-Armitage trend tests with different scores and for a constrained
likelihood ratio test. For significance levels below 0.05, asymptotic
approximations may give a test size up to 20 times the nominal level, and
should therefore be used with caution. Further, calculating p-values based on
exact conditional enumeration is a powerful, valid and computationally feasible
approach, and we advocate its use in genetic association studies.


title:
Exact conditional p-values from arbitrary ranking of a sample space: An
  application to genome-wide association studies

abstract:
  We introduce a method for computation of exact conditional efficiency robust
enumeration p-values for detection of genotype--phenotype associations at a
single bi-allelic genetic locus. Our method can be based on any arbitrary
ranking test statistics, such as efficiency robust test statistics or
asymptotic p-values. The resulting p-values are exact conditional enumeration
p-values and satisfy the basic statistical validity property. Practically, the
method allows performing statistically valid significance testing in genomic
analyses with unknown modes of inheritance at individual bi-allelic genetic
loci -- the situation typical in genome-wide association studies. We provide an
open-source R code implementing the method.


title:
A Conjectural Formula for Genus One Gromov-Witten Invariants of a Class
  of Local Calabi-Yau n-folds

abstract:
  We conjecture a formula for the generating function of genus one
Gromov-Witten invariants of the local Calabi-Yau manifolds which are the total
spaces of splitting bundles over projective spaces. We prove this conjecture in
several special cases, and assuming the validity of our conjecture we check the
integrality of genus one BPS numbers of local Calabi-Yau 5-folds defined by A.
Klemm and R. Pandharipande.


title: Stabilizer Rigidity in Irreducible Group Actions

abstract:
  We consider irreducible actions of locally compact product groups, and of
higher rank semi-simple Lie groups. Using the intermediate factor theorems of
Bader-Shalom and Nevo-Zimmer, we show that the action stabilizers, and all
irreducible invariant random subgroups, are co-amenable in their normal
closure. As a consequence, we derive rigidity results on irreducible actions
that generalize and strengthen the results of Bader-Shalom and Stuck-Zimmer.


title: Superpositions of Lorentzians as the class of causal functions

abstract:
  We prove that all functions obeying the Kramers-Kronig relations can be
approximated as superpositions of Lorentzian functions, to any precision. As a
result, the typical text-book analysis of dielectric dispersion response
functions in terms of Lorentzians may be viewed as encompassing the whole class
of causal functions. A further consequence is that Lorentzian resonances may be
viewed as possible building blocks for engineering any desired metamaterial
response, for example by use of split ring resonators of different parameters.
Two example functions, far from typical Lorentzian resonance behavior, are
expressed in terms of Lorentzian superpositions: A steep dispersion medium that
achieves large negative susceptibility with arbitrarily low loss/gain, and an
optimal realization of a perfect lens over a bandwidth. Error bounds are
derived for the approximation.


title:
Integrated optical waveplates for arbitrary operations on
  polarization-encoded single-qubits

abstract:
  Integrated photonic technologies applied to quantum optics have recently
enabled a wealth of breakthrough experiments in several quantum information
areas. Path encoding was initially used to demonstrate operations on single or
multiple qubits. However, a polarization encoding approach is often simpler and
more effective. Two-qubits integrated logic gates as well as complex
interferometric structures have been successfully demonstrated exploiting
polarization encoding in femtosecond-laser-written photonic circuits. Still,
integrated devices performing single-qubit rotations are missing. Here we
demonstrate waveguide-based waveplates, fabricated by femtosecond laser pulses,
capable to effectively produce arbitrary single-qubit operations in the
polarization encoding. By exploiting these novel components we fabricate and
test a compact device for the quantum state tomography of two
polarization-entangled photons. The integrated optical waveplates complete the
toolbox required for a full manipulation of polarization-encoded qubits
on-chip, disclosing new scenarios for integrated quantum computation, sensing
and simulation, and possibly finding application also in standard photonic
devices.


title:
Organization of the Hilbert Space for Exact Diagonalization of Hubbard
  Model

abstract:
  We present an alternative scheme to the widely used method of representing
the basis of one-band Hubbard model through the relation
$I=I_{\uparrow}+2^{M}I_{\downarrow}$ given by H. Q. Lin and J. E. Gubernatis
[Comput. Phys. 7, 400 (1993)], where $I_{\uparrow}$, $I_{\downarrow}$ and $I$
are the integer equivalents of binary representations of occupation patterns of
spin up, spin down and both spin up and spin down electrons respectively, with
$M$ being the number of sites. We compute and store only $I_{\uparrow}$ or
$I_{\downarrow}$ at a time to generate the full Hamiltonian matrix. The
non-diagonal part of the Hamiltonian matrix given as
${\cal{I}}_{\downarrow}\otimes{\bf{H}_{\uparrow}} \oplus
{\bf{H}_{\downarrow}}\otimes{\cal{I}}_{\uparrow}$ is generated using a
bottom-up approach by computing the small matrices ${\bf{H}_{\uparrow}}$(spin
up hopping Hamiltonian) and ${\bf{H}_{\downarrow}}$(spin down hopping
Hamiltonian) and then forming the tensor product with respective identity
matrices ${\cal{I}}_{\downarrow}$ and ${\cal{I}}_{\uparrow}$, thereby saving
significant computation time and memory. We find that the total CPU time to
generate the non-diagonal part of the Hamiltonian matrix using the new one spin
configuration basis scheme is reduced by about an order of magnitude as
compared to the two spin configuration basis scheme. The present scheme is
shown to be inherently parallelizable. Its application to translationally
invariant systems, computation of Green's functions and in impurity solver part
of DMFT procedure is discussed and its extention to other models is also
pointed out.


title:
Superconvergence of a Galerkin FEM for Higher-Order Elements in
  Convection-Diffusion Problems

abstract:
  In this paper we present a first supercloseness analysis for higher-order
Galerkin FEM applied to a singularly perturbed convection-diffusion problem.
Using a solution decomposition and a special representation of our finite
element space we are able to prove a supercloseness property of order p+1/4 in
the energy norm where the polynomial order p>=3 is odd.


title: On block coherence of frames

abstract:
  Block coherence of matrices plays an important role in analyzing the
performance of block compressed sensing recovery algorithms (Bajwa and Mixon,
2012). In this paper, we characterize two block coherence metrics: worst-case
and average block coherence. First, we present lower bounds on worst-case block
coherence, in both the general case and also when the matrix is constrained to
be a union of orthobases. We then present deterministic matrix constructions
based upon Kronecker products which obtain these lower bounds. We also
characterize the worst-case block coherence of random subspaces. Finally, we
present a flipping algorithm that can improve the average block coherence of a
matrix, while maintaining the worst-case block coherence of the original
matrix. We provide numerical examples which demonstrate that our proposed
deterministic matrix construction performs well in block compressed sensing.


title:
Multi-Objective Beamforming for Secure Communication in Systems with
  Wireless Information and Power Transfer

abstract:
  In this paper, we study power allocation for secure communication in a
multiuser multiple-input single-output (MISO) downlink system with simultaneous
wireless information and power transfer. The receivers are able to harvest
energy from the radio frequency when they are idle. We propose a
multi-objective optimization problem for power allocation algorithm design
which incorporates two conflicting system objectives: total transmit power
minimization and energy harvesting efficiency maximization. The proposed
problem formulation takes into account a quality of service (QoS) requirement
for the system secrecy capacity. Our designs advocate the dual use of
artificial noise in providing secure communication and facilitating efficient
energy harvesting. The multi-objective optimization problem is non-convex and
is solved by a semidefinite programming (SDP) relaxation approach which results
in an approximate of solution.
  A sufficient condition for the global optimal solution is revealed and the
accuracy of the approximation is examined. To strike a balance between
computational complexity and system performance, we propose two suboptimal
power allocation schemes. Numerical results not only demonstrate the excellent
performance of the proposed suboptimal schemes compared to baseline schemes,
but also unveil an interesting trade-off between energy harvesting efficiency
and total transmit power.


title:
Relations Between Stochastic Orderings and generalized Stochastic
  Precedence

abstract:
  The concept of "stochastic precedence" between two real-valued random
variables has often emerged in different applied frameworks. In this paper we
consider a slightly more general, and completely natural, concept of stochastic
precedence and analyze its relations with the notions of stochastic ordering.
Such a study leads us to introducing some special classes of bivariate copulas.
Motivations for our study can arise from different fields. In particular we
consider the frame of Target-Based Approach in decisions under risk. This
approach has been mainly developed under the assumption of stochastic
independence between "Prospects" and "Targets". Our analysis concerns the case
of stochastic dependence.


title:
On Robustness Criteria and Robust Topology Optimization with Uncertain
  Loads

abstract:
  We propose a new algorithm for the solution of the robust multiple-load
topology optimization problem. The algorithm can be applied to any type of
problem, e.g., truss topology, variable thickness sheet or free material
optimization. We assume that the given loads are uncertain and can be subject
to small random perturbations. Furthermore, we define a rigorous measure of
robustness of the given design with respect to these perturbations. To
implement the algorithm, the users only need software to solve their standard
multiple-load problem. Additionally, they have to solve a few small-dimensional
eigenvalue problems. Numerical examples demonstrate the efficiency of our
approach.


title:
Recent Results on the 3-Loop Heavy Flavor Wilson Coefficients in
  Deep-Inelastic Scattering

abstract:
  We report on recent progress in the calculation of the 3-loop massive Wilson
coefficients in deep-inelastic scattering at general values of $N$ for neutral
and charged current reactions in the asymptotic region $Q^2 \gg m^2$.


title: The early impact histories of meteorite parent bodies

abstract:
  We have developed a statistical framework that uses collisional evolution
models, shock physics modeling and scaling laws to determine the range of
plausible collisional histories for individual meteorite parent bodies. It is
likely that those parent bodies that were not catastrophically disrupted
sustained hundreds of impacts on their surfaces - compacting, heating, and
mixing the outer layers; it is highly unlikely that many parent bodies escaped
without any impacts processing the outer few kilometers. The first 10 - 20 Myr
were the most important time for impacts, both in terms of the number of
impacts and the increase of specific internal energy due to impacts. The model
has been applied to evaluate the proposed impact histories of several meteorite
parent bodies: up to 10 parent bodies that were not disrupted in the first 100
Myr experienced a vaporizing collision of the type necessary to produce the
metal inclusions and chondrules on the CB chondrite parent; around 1 - 5% of
bodies that were catastrophically disrupted after 12 Myr sustained impacts at
times that match the heating events recorded on the IAB/winonaite parent body;
more than 75% of 100 km radius parent bodies which survived past 100 Myr
without being disrupted sustained an impact that excavates to the depth
required for mixing in the outer layers of the H chondrite parent body; and to
protect the magnetic field on the CV chondrite parent body, the crust would
have had to have been thick (~ 20 km) in order to prevent it being punctured by
impacts.


title:
Rotation of a single acetylene molecule on Cu(001) by tunneling
  electrons in STM

abstract:
  We study the elementary processes behind one of the pioneering works on STM
controlled reactions of single molecules [Stipe et al., Phys. Rev. Lett. 81,
1263 (1998)]. Using the Keldysh-Green function approach for the vibrational
generation rate in combination with DFT calculations to obtain realistic
parameters we reproduce the experimental rotation rate of an acetylene molecule
on a Cu(100) surface as a function of bias voltage and tunneling current. This
combined approach allows us to identify the reaction coordinate mode of the
acetylene rotation and its anharmonic coupling with the C-H stretch mode. We
show that three different elementary processes, the excitation of C-H stretch,
the overtone ladder climbing of the hindered rotational mode, and the
combination band excitation together explain the rotation of the acetylene
molecule on Cu(100).


title: Semi-counterfactual Cryptography

abstract:
  In counterfactual quantum key distribution (QKD), two remote parties can
securely share random polarization-encoded bits through the blocking rather
than the transmission of particles. We propose a semi-counterfactual QKD, i.e.,
one where the secret bit is shared, and also encoded, based on the blocking or
non-blocking of a particle. The scheme is thus semi-counterfactual and not
based on polarization encoding. As with other counterfactual schemes and the
Goldenberg-Vaidman protocol, but unlike BB84, the encoding states are
orthogonal and security arises ultimately from single-particle non-locality.
Unlike any of them, however, the secret bit generated is maximally
indeterminate until the joint action of Alice and Bob. We prove the general
security of the protocol, and study the most general photon-number-preserving
incoherent attack in detail.


title:
Bond-selective fragmentation of water molecules with intense, ultrafast,
  carrier envelope phase stabilized laser pulses

abstract:
  Carrier envelope phase (CEP) stabilized pulses of intense 800 nm light of 5
fs duration are used to probe the dissociation dynamics of dications of
isotopically-substituted water, HOD. HOD$^{2+}$ dissociates into either H$^+$ +
OD$^+$ or D$^+$ + OH$^+$. The branching ratio for these two channels is
CEP-dependent; the OD$^+$/OH$^+$ ratio (relative to that measured with
CEP-unstabilized pulses) varies from 150% to over 300% at different CEP values,
opening prospects of isotope-dependent control over molecular bond breakage.
The kinetic energy released as HOD$^{2+}$ Coulomb explodes is also
CEP-dependent. Formidable theoretical challenges are identified for proper
insights into the overall dynamics which involve non-adiabatic field ionization
from HOD to HOD$^+$ and, thence, to HOD$^{2+}$ via electron rescattering.


title:
Distributed Association Control and Relaying in MillimeterWave Wireless
  Access Networks

abstract:
  In millimeterWave wireless networks the rapidly varying wireless channels
demand fast and dynamic resource allocation mechanisms. This challenge is
hereby addressed by a distributed approach that optimally solves the
fundamental resource allocation problem of joint client association and
relaying. The problem is posed as a multi assignment optimization, for which a
novel solution method is established by a series of transformations that lead
to a tractable minimum cost flow problem. The method allows to design
distributed auction solution algorithms where the clients and relays act
asynchronously. The computational complexity of the new algorithms is much
better than centralized general-purpose solvers. It is shown that the
algorithms always converge to a solution that maximizes the total network
throughput within a desired bound. Both theoretical and numerical results
evince numerous useful properties in comparison to standard approaches and the
potential applications to forthcoming millimeterWave wireless access networks.


title: Th\'eor\`emes de type Fouvry--Iwaniec pour les entiers friables

abstract:
  An integer n is said to be y-friable if its largest prime factor $P^+(n)$ is
less than y. In this paper, it is shown that the y-friable integers less than x
have a weak exponent of distribution at least $3/5-\varepsilon$ when $(\log
x)^c\leq y\leq x^{1/c}$ for some $c=c(\varepsilon)\geq 1$, that is, they are
well distributed in the residue classes of a fixed integer $a$, on average over
moduli $\leq x^{3/5-\varepsilon}$ for each fixed $a\neq 0$ and $\varepsilon>0$.
We present an application to the estimation of the sum $\sum_{2\leq n\leq x,
P^+(n)\leq y}\tau(n-1)$ when $(\log x)^c\leq y$. This follows and improves on
previous work of Fouvry and Tenenbaum. Our proof combines the dispersion method
of Linnik in the setting of Bombieri, Fouvry, Friedlander and Iwaniec, and
recent work of Harper on friable integers in arithmetic progressions.


title: Specific Heat Capacity of TiO2 Nanoparticles

abstract:
  We have calculated heat capacity of TiO2 nanoparticles in three stable
polymorphs by applying size and surface effects on heat capacity of the bulk
structure. The size and surface corrections were imposed on the acoustic and
optical bulk phonons, separately. The model used in the present work is a
simple modification of the model proposed by Wang et al. We applied the
modified model to obtain the specific heat capacity of 10-100 nm TiO2
nanoparticles. A very good consistency is observed between the computational
and experimental data. Based on the modified model, particles with sizes larger
than 70 nm behave like bulk structure. In addition, the heat capacity of
particles smaller than 15 nm become independent from their structure details
while demonstrating a drastic increase.


title: Anelastic relaxor behavior of Pb(Mg1/3Nb2/3)O3

abstract:
  Elastic storage modulus and loss of relaxor lead magnesium niobate ceramics,
Pb(Mg1/3Nb2/3)O3, have been measured with dynamic mechanical analyzer in single
cantilever mode in the temperature range from 170 K to 320 K and at frequencies
from 0.1 Hz to 50 Hz. The dependence of the elastic susceptibility (inverse
modulus) on temperature and frequency of the driving force has characteristics
of typical relaxor behavior that can be well described with the Vogel-Fulcher
law. The parameters of the Vogel-Fulcher relation exhibit similar values for
the dielectric and anelastic relaxations. Similarities and differences between
anelastic and dielectric relaxor behaviors are identified.


title: Regularity of joint-meet ideals of distributive lattices

abstract:
  Let $L$ be a distributive lattice and $R(L)$ the associated Hibi ring. We
compute $\reg R(L)$ when $L$ is a planar lattice and give a lower bound for
$\reg R(L)$ when $L$ is non-planar, in terms of the combinatorial data of $L.$
As a consequence, we characterize the distributive lattices $L$ for which the
associated Hibi ring has a linear resolution.


title:
Two-orbital physics of high spin fermionic alkaline earth atoms confined
  in a one-dimensional chain

abstract:
  We study the effect of the coupling between the electronic ground state of
high spin alkaline-earth fermionic atoms and their metastable optically excited
state, when the system is confined in a one-dimensional chain, and show that
the system provides a possible realization of a finite momentum pairing
(Fulde-Ferrell-Larkin-Ovchinnikov-like) state without spin- or bare mass
imbalance. We determine the $\beta$-functions of the renormalization group
trajectories for general spin and analyze the structure of the possible gapped
and gapless states in the hydrodynamic limit. Due to the SU(N) symmetry in the
spin space, complete mode separation can not be observed even in the fully
gapless 2N-component Luttinger liquid state. Contrary, 4 velocities
characterize the system. We solve the renormalization group equations for
spin-9/2 strontium-87 isotope and analyze in detail its phase diagram. The
fully gapless Luttinger liquid state does not stabilize in the two-orbital
system of the $^{87}$Sr atoms, instead, different gapped non-Gaussian fixed
points are identified either with dominant density or superconducting
fluctuations. The superconducting states are stable in a nontrivial shaped
region in the parameter space as a consequence of the coupling between the two
electronic states.


title:
Integral representation of random variables with respect to Gaussian
  processes

abstract:
  It was shown in Mishura et al. (Stochastic Process. Appl. 123 (2013)
2353-2369), that any random variable can be represented as improper pathwise
integral with respect to fractional Brownian motion. In this paper, we extend
this result to cover a wide class of Gaussian processes. In particular, we
consider a wide class of processes that are H\"{o}lder continuous of order
$\alpha>1/2$ and show that only local properties of the covariance function
play role for such results.


title:
Products of Rectangular Random Matrices: Singular Values and Progressive
  Scattering

abstract:
  We discuss the product of $M$ rectangular random matrices with independent
Gaussian entries, which have several applications including wireless
telecommunication and econophysics. For complex matrices an explicit expression
for the joint probability density function is obtained using the
Harish-Chandra--Itzykson--Zuber integration formula. Explicit expressions for
all correlation functions and moments for finite matrix sizes are obtained
using a two-matrix model and the method of bi-orthogonal polynomials. This
generalises the classical result for the so-called Wishart--Laguerre Gaussian
unitary ensemble (or chiral unitary ensemble) at M=1, and previous results for
the product of square matrices. The correlation functions are given by a
determinantal point process, where the kernel can be expressed in terms of
Meijer $G$-functions. We compare the results with numerical simulations and
known results for the macroscopic level density in the limit of large matrices.
The location of the endpoints of support for the latter are analysed in detail
for general $M$. Finally, we consider the so-called ergodic mutual information,
which gives an upper bound for the spectral efficiency of a MIMO communication
channel with multi-fold scattering.


title:
Simple concentration-dependent pair interaction model for large-scale
  simulations of Fe-Cr alloys

abstract:
  This work is motivated by the need for large-scale simulations to extract
physical information on the iron-chromium system that is a binary model alloy
for ferritic steels used or proposed in many nuclear applications. From
first-principles calculations and the experimental critical temperature we
build a new energetic rigid lattice model based on pair interactions with
concentration and temperature dependence. Density functional theory
calculations in both norm-conserving and projector augmented-wave approaches
have been performed. A thorough comparison of these two different ab initio
techniques leads to a robust parametrization of the Fe-Cr Hamiltonian.
Mean-field approximations and Monte Carlo calculations are then used to account
for temperature effects. The predictions of the model are in agreement with the
most recent phase diagram at all temperatures and compositions. The solubility
of Cr in Fe below 700 K remains in the range of about 6 to 12%. It reproduces
the transition between the ordering and demixing tendency and the spinodal
decomposition limits are also in agreement with the values given in the
literature.


title: On the convergence of weighted-average consensus

abstract:
  In this note we give sufficient conditions for the convergence of the
iterative algorithm called weighted-average consensus in directed graphs. We
study the discrete-time form of this algorithm. We use standard techniques from
matrix theory to prove the main result. As a particular case one can obtain
well-known results for non-weighted average consensus. We also give a corollary
for undirected graphs.


title: Cooperative Caching Framework for Mobile Cloud Computing

abstract:
  Due to the advancement in mobile devices and wireless networks mobile cloud
computing, which combines mobile computing and cloud computing has gained
momentum since 2009. The characteristics of mobile devices and wireless network
makes the implementation of mobile cloud computing more complicated than for
fixed clouds. This section lists some of the major issues in Mobile Cloud
Computing. One of the key issues in mobile cloud computing is the end to end
delay in servicing a request. Data caching is o ne of the techniques widely
used in wired and wireless networks to improve data access efficiency. In this
paper we explore the possibility of a cooperative caching approach to enhance
data access efficiency in mobile cloud computing. The proposed approach is
based on cloudlets, one of the architecture designed for mobile cloud
computing.


title:
Constraint on Heavy Element Production in Inhomogeneous Big-Bang
  Nucleosynthesis from The Light-Element Observations

abstract:
  We investigate the observational constraints on the inhomogeneous big-bang
nucleosynthesis that Matsuura et al. suggested the possibility of the heavy
element production beyond ${}^7$Li in the early universe. From the
observational constraints on light elements of ${}^4$He and D, possible regions
are found on the plane of the volume fraction of the high density region
against the ratio between high-and low-density regions. In these allowed
regions, we have confirmed that the heavy elements beyond Ni can be produced
appreciably, where $p$- and/or $r$-process elements are produced well
simultaneously.


title: Twisted N=4 Super Yang-Mills Theory in Omega-background

abstract:
  We study the twisted N=4 super Yang-Mills theories in the Omega-background
with the constant R-symmetry Wilson line gauge field. Based on the
classification of topological twists of N=4 supersymmetry (the half, the
Vafa-Witten and the Marcus twists), we construct the deformed off-shell
supersymmetry associated with the scalar supercharges for these twists. We find
that the Omega-deformed action is written in the exact form with respect to the
scalar supercharges as in the undeformed case.


title:
Full Monte Carlo simulations of radio emission from extensive air
  showers with CoREAS

abstract:
  CoREAS is a Monte Carlo simulation code for the calculation of radio emission
from extensive air showers. It is based on the "endpoint formalism" for
radiation from moving charges implemented directly in CORSIKA. Consequently,
the full complexity of the air-shower physics is taken into account without the
need for approximations or assumptions on the emission mechanism. We present
results of simulations for an unthinned shower performed with CoREAS for both
MHz and GHz frequencies. At MHz frequencies, the simulations predict the
well-known mixture of geomagnetic and charge excess radiation. At GHz
frequencies, the emission is strongly influenced by Cherenkov effects arising
from the varying refractive index in the atmosphere. In addition, a qualitative
difference in the symmetry of the GHz radiation pattern is observed when
compared to the ones at lower frequencies. We also discuss the strong increase
in the ground area subtended by the radio emission when going from
near-vertical to very inclined geometries, making very inclined air showers the
most promising ones for cosmic ray radio detection.


title:
Primordial star formation: relative impact of H2 three-body rates and
  initial conditions

abstract:
  Population III stars are the first stars in the Universe to form at z=20-30
out of a pure hydrogen and helium gas in minihalos of 10^5-10^6 M$_\odot$ .
Cooling and fragmentation is thus regulated via molecular hydrogen. At
densities above 10^8 cm$^{-3}$, the three-body H2 formation rates are
particularly important for making the gas fully molecular. These rates were
considered to be uncertain by at least a few orders of magnitude. We explore
the impact of new accurate three-body H2 formation rates derived by Forrey
(2013) for three different minihalos, and compare to the results obtained with
three-body rates employed in previous studies. The calculations are performed
with the cosmological hydrodynamics code ENZO (release 2.2) coupled with the
chemistry package KROME (including a network for primordial chemistry), which
was previously shown to be accurate in high resolution simulations. While the
new rates can shift the point where the gas becomes fully molecular, leading to
a different thermal evolution, there is no trivial trend in how this occurs.
While one might naively expect the results to be inbetween the calculations
based on Palla et al. (1983) and Abel et al. (2002), the behavior can be close
to the former or the latter depending on the dark matter halo that is explored.
We conclude that employing the correct three-body rates is about as equally
important as the use of appropriate initial conditions, and that the resulting
thermal evolution needs to be calculated for every halo individually.


title:
Heavy flavour in nucleus-nucleus collisions at RHIC and LHC: a Langevin
  approach

abstract:
  A snapshot of the results for heavy-flavour observables in heavy-ion (AA)
collisions at RHIC and LHC obtained with our transport calculations is
displayed. The initial charm and beauty production is simulated through pQCD
tools (POWHEG+PYTHIA) and is validated through the comparison with data from pp
collisions. The propagation of c and b quarks in the medium formed in heavy-ion
collisions is studied through a transport setup based on the relativistic
Langevin equation. With respect to past works we perform a more systematic
study, providing results with different choices of transport coefficients,
either from weak-coupling calculations or from lattice-QCD simulations. Our
findings are compared to a rich set of experimental data (D-mesons,
non-photonic electrons, non-prompt J/\psi's) which have meanwhile become
accessible.


title: Community detection for networks with unipartite and bipartite structure

abstract:
  Finding community structures in networks is important in network science,
technology, and applications. To date, most algorithms that aim to find
community structures only focus either on unipartite or bipartite networks. A
unipartite network consists of one set of nodes and a bipartite network
consists of two nonoverlapping sets of nodes with only links joining the nodes
in different sets. However, a third type of network exists, defined here as the
mixture network. Just like a bipartite network, a mixture network also consists
of two sets of nodes, but some nodes may simultaneously belong to two sets,
which breaks the nonoverlapping restriction of a bipartite network. The mixture
network can be considered as a general case, with unipartite and bipartite
networks viewed as its limiting cases. A mixture network can represent not only
all the unipartite and bipartite networks, but also a wide range of real-world
networks that cannot be properly represented as either unipartite or bipartite
networks in fields such as biology and social science. Based on this
observation, we first propose a probabilistic model that can find modules in
unipartite, bipartite, and mixture networks in a unified framework based on the
link community model for a unipartite undirected network [B Ball et al (2011
Phys. Rev. E 84 036103)]. We test our algorithm on synthetic networks (both
overlapping and nonoverlapping communities) and apply it to two real-world
networks: a southern women bipartite network and a human transcriptional
regulatory mixture network. The results suggest that our model performs well
for all three types of networks, is competitive with other algorithms for
unipartite or bipartite networks, and is applicable to real-world networks.


title: On linear periods

abstract:
  Let $\pi'$ be a cuspidal automorphic representation of $GL_{2n}$, which is
assumed to be the Jacquet-Langlands transfer from a cuspidal automorphic
representation $\pi$ of $GL_{2m}(D)$, where $D$ is a division algebra so that
$GL_{2m}(D)$ is an inner form of $GL_{2n}$. In this paper, we consider the
relation between linear periods on $\pi$ and $\pi'$. We conjecture that the
non-vanishing of the linear period on $\pi$ would imply the non-vanishing of
that on $\pi'$. We illustrate an approach using a relative trace formula
towards this conjecture, and prove the existence of smooth transfer over
non-archimedean local fields.


title: Damping of Primordial Gravitational Waves from Generalized Sources

abstract:
  It has been shown that a cosmological background with an anisotropic stress
tensor, appropriate for a free streaming thermal neutrino background, can damp
primordial gravitational waves after they enter the horizon, and can thus
affect the CMB B-mode polarization signature due to such tensor modes. Here we
generalize this result, and examine the sensitivity of this effect to non-zero
neutrino masses, extra neutrino species, and also a possible relativistic
background of axions from axion strings. In particular, additional neutrinos
with cosmologically interesting neutrino masses at the O(1) eV level will
noticeably reduce damping compared to massless neutrinos for gravitational wave
modes with $k\tau_0 \approx 100-200$, where $\tau_0 \approx 2/H_0$ and $H_0$ is
the present Hubble parameter, while an axion background would produce a
phase-dependent damping distinct from that produced by neutrinos.


title: The algebra $U_q({\mathfrak{sl}_2})$ in disguise

abstract:
  We discuss a connection between the algebra $U_q({\mathfrak{sl}_2})$ and the
tridiagonal pairs of $q$-Racah type. To describe the connection, let $x,y^{\pm
1},z$ denote the equitable generators for $U_q({\mathfrak{sl}_2})$. Let
$U^\vee_q$ denote the subalgebra of $U_q({\mathfrak{sl}_2})$ generated by
$x,y^{-1},z$. Using a tridiagonal pair of $q$-Racah type we construct two
finite-dimensional $U^\vee_q$-modules. The constructions yield two nonstandard
presentations of $U^\vee_q$ by generators and relations. These presentations
are investigated in detail.


title: The number of complete exceptional sequences for a Dynkin algebra

abstract:
  We consider Dynkin algebras, these are the hereditary artin algebras of
finite representation type. The indecomposable modules for a Dynkin algebra
correspond bijectively to the positive roots of a Dynkin diagram. Given a
Dynkin algebra with n simple modules, a complete exceptional sequence is a
sequence M_1,..., M_n of indecomposable modules such that Hom(M_i,M_j) = 0 =
Ext(M_i,M_j) for i > j. The aim of this paper is to determine the number of
complete exceptional sequences for any Dynkin algebra.
  There are direct connections between the representation theory of a Dynkin
algebra A and the lattice L of non-crossing partitions of the same Dynkin type:
As Ingalls and Thomas have shown, the lattice of the thick subcategories of mod
A can be identified with L. Hubery and Krause have pointed out that this
identification provides a bijection between the complete exceptional sequences
for A and the maximal chains in L. Thus, our calculations may also be
considered as a categorification of results concerning non-crossing partitions.


title: Cylinders and paths in simplicial categories

abstract:
  We prove the uniqueness, the functoriality and the naturality of cylinder
objects and path objects in closed simplicial model categories.


title: Counter operation in nonlinear micro-electro-mechanical resonators

abstract:
  This paper discusses a logical operation of multi-memories that consist of
coupled nonlinear micro-electro-mechanical systems (MEMS) resonators. A MEMS
resonator shows two coexisting stable states when nonlinear responses appear.
Previous studies addressed that a micro- or nano-electrical-mechanical
resonator can be utilized as a mechanical 1-bit memory or mechanical logic
gates. The next phase is the development of logic system with coupled
multi-resonators. From the viewpoint of application of nonlinear dynamics in
coupled MEMS resonators, we show the first experimental success of the
controlling nonlinear behavior as a 2-bit binary counter.


title:
Unidirectional direct current in coupled nanomechanical resonators by
  tunable symmetry breaking

abstract:
  We investigate theoretically the non-linear dynamics of a coupled
nanomechanical oscillator. Under a weak radio frequency excitation, the
resonators can be parametrically tuned into a self-sustained oscillatory
regime. The transfer of electrons from one contact to the other is then
mechanically assisted, generating a rectified current. The direction of the
rectified current is, in most unstable regions, determined by the phase shift
between the mechanical oscillations and the signal. However, we locate
intriguing parametrical regions of uni-directional rectified current,
suggesting a practical scheme for the realization of a self-powered device in
the nanoscale. In these regions, a dynamical symmetry breaking is induced by
the non-linear coupling of the mechanical and electrical degrees of freedom.
When operating within the Coulomb blockade limit, we locate bands of
instability of enhanced gain.


title:
Safe Screening With Variational Inequalities and Its Application to
  LASSO

abstract:
  Sparse learning techniques have been routinely used for feature selection as
the resulting model usually has a small number of non-zero entries. Safe
screening, which eliminates the features that are guaranteed to have zero
coefficients for a certain value of the regularization parameter, is a
technique for improving the computational efficiency. Safe screening is gaining
increasing attention since 1) solving sparse learning formulations usually has
a high computational cost especially when the number of features is large and
2) one needs to try several regularization parameters to select a suitable
model. In this paper, we propose an approach called "Sasvi" (Safe screening
with variational inequalities). Sasvi makes use of the variational inequality
that provides the sufficient and necessary optimality condition for the dual
problem. Several existing approaches for Lasso screening can be casted as
relaxed versions of the proposed Sasvi, thus Sasvi provides a stronger safe
screening rule. We further study the monotone properties of Sasvi for Lasso,
based on which a sure removal regularization parameter can be identified for
each feature. Experimental results on both synthetic and real data sets are
reported to demonstrate the effectiveness of the proposed Sasvi for Lasso
screening.


title:
Optimal error estimate for semi-implicit space-time discretization for
  the equations describing incompressible generalized Newtonian fluids

abstract:
  In this paper we study the numerical error arising in the space-time
approximation of unsteady generalized Newtonian fluids which possess a
stress-tensor with $(p,\delta)$-structure. A semi-implicit time-discretization
scheme coupled with conforming inf-sup stable finite element space
discretization is analyzed. The main result, which improves previous suboptimal
estimates as those in [A. Prohl, and M. Ruzicka, SIAM J. Numer. Anal., 39
(2001), pp. 214--249] is the optimal $O(k+h)$ error-estimate valid in the range
$p\in (3/2,2]$, where $k$ and $h$ are the time-step and the mesh-size,
respectively. Our results hold in three-dimensional domains (with periodic
boundary conditions) and are uniform with respect to the degeneracy parameter
$\in [0,\delta_0]$ of the extra stress tensor.


title: Trapping Dirac fermions in tubes generated by two scalar fields

abstract:
  In this work we consider $(1,1)-$dimensional resonant Dirac fermionic states
on tube-like topological defects. The defects are formed by rings in $(2,1)$
dimensions, constructed with two scalar field $\phi$ and $\chi$, and embedded
in the $(3,1)-$dimensional Minkowski spacetime. The tube-like defects are
attained from a lagrangian density explicitly dependent with the radial
distance $r$ relative to the ring axis and the radius and thickness of the its
cross-section are related to the energy density. For our purposes we analyze a
general Yukawa-like coupling between the topological defect and the fermionic
field $\eta F(\phi,\chi)\bar\psi\psi$. With a convenient decomposition of the
fermionic fields in left- and right- chiralities, we establish a coupled set of
first order differential equations for the amplitudes of the left- and right-
components of the Dirac field. After decoupling and decomposing the amplitudes
in polar coordinates, the radial modes satisfy Schr\"odinger-like equations
whose eigenvalues are the masses of the fermionic resonances. With
$F(\phi,\chi)=\phi\chi$ the Schr\"odinger-like equations are numerically solved
with appropriated boundary conditions. Several resonance peaks for both
chiralities are obtained, and the results are confronted with the qualitative
analysis of the Schr\"odinger-like potentials.


title:
Nonlinear Intrinsic Variables and State Reconstruction in Multiscale
  Simulations

abstract:
  Finding informative low-dimensional descriptions of high-dimensional
simulation data (like the ones arising in molecular dynamics or kinetic Monte
Carlo simulations of physical and chemical processes) is crucial to
understanding physical phenomena, and can also dramatically assist in
accelerating the simulations themselves. In this paper, we discuss and
illustrate the use of nonlinear intrinsic variables (NIV) in the mining of
high-dimensional multiscale simulation data. In particular, we focus on the way
NIV allows us to functionally merge different simulation ensembles, and
different partial observations of these ensembles, as well as to infer
variables not explicitly measured. The approach relies on certain simple
features of the underlying process variability to filter out measurement noise
and systematically recover a unique reference coordinate frame. We illustrate
the approach through two distinct sets of atomistic simulations: a stochastic
simulation of an enzyme reaction network exhibiting both fast and slow time
scales, and a molecular dynamics simulation of alanine dipeptide in explicit
water.


title: Stochastic switching in slow-fast systems: a large fluctuation approach

abstract:
  In this paper we develop a perturbation method to predict the rate of
occurrence of rare events for singularly perturbed stochastic systems using a
probability density function approach. In contrast to a stochastic normal form
approach, we model rare event occurrences due to large fluctuations
probabilistically and employ a WKB ansatz to approximate their rate of
occurrence. This results in the generation of a two-point boundary value
problem that models the interaction of the state variables and the most likely
noise force required to induce a rare event. The resulting equations of motion
of describing the phenomenon are shown to be singularly perturbed. Vastly
different time scales among the variables are leveraged to reduce the dimension
and predict the dynamics on the slow manifold in a deterministic setting. The
resulting constrained equations of motion may be used to directly compute an
exponent that determines the probability of rare events.
  To verify the theory, a stochastic damped Duffing oscillator with three
equilibrium points (two sinks separated by a saddle) is analyzed. The predicted
switching time between states is computed using the optimal path that resides
in an expanded phase space. We show that the exponential scaling of the
switching rate as a function of system parameters agrees well with numerical
simulations. Moreover, the dynamics of the original system and the reduced
system via center manifolds are shown to agree in an exponentially scaling
sense.


title:
Quantum quench in the Luttinger model with finite temperature initial
  state

abstract:
  We study the non-equilibrium dynamics of the Luttinger model after a quantum
quench, when the initial state is a finite temperature thermal equilibrium
state. The diagonal elements of the density matrix in the steady state show
thermal features for high temperature initial states only, otherwise retain
highly non-thermal character. The time evolution of Uhlmann fidelity, which
measures the distance between the time evolved and initial states, is evaluated
for arbitrary initial temperatures and quench protocols. In the long time
limit, the overlap between the time evolved and initial system decreases
exponentially with the temperature with a universal prefactor. Within
perturbation theory, the statistics of final total energy and work are
numerically evaluated in the case of a sudden quench, which yield identical
distributions at zero temperature. In both statistics, temperature effects are
more significant in small systems. The Dirac-delta peak at the adiabatic ground
state energy remains present in the probability distribution of the total
energy, but disappears from the work distribution at non-zero initial
temperatures.


title:
Type II Perfect Absorption and Amplification Modes with Controllable
  Bandwidth in PT-Symmetric/Traditional Bragg Grating Combined Structures

abstract:
  We reveal previously unnoticed Type II perfect absorption and amplification
modes of optical scattering system. These modes, in contrast to the
counterparts in recent works [Phys. Rev. A 82, 031801 (2010); Phys. Rev. Lett.
106, 093902 (2011).] which could be referred as Type I modes, appear at a
continuous region along the real frequency axis with any frequency. The Type II
modes can be demonstrated in the PT-symmetric/traditional Bragg grating
combined structures. A series of exotic nonreciprocal absorption and
amplification behaviours are observed in the combined structures, making them
have potential for versatile devices acting simultaneously as a perfect
absorber, an amplifier, and an ultra-narrowband filter. Based on the properties
of Type II modes, we also propose structures with controllable perfect
absorption and amplification bandwidth at any single or multiple wavelengths.


title:
Towards a System Theoretic Approach to Wireless Network Capacity in
  Finite Time and Space

abstract:
  In asymptotic regimes, both in time and space (network size), the derivation
of network capacity results is grossly simplified by brushing aside queueing
behavior in non-Jackson networks. This simplifying double-limit model, however,
lends itself to conservative numerical results in finite regimes. To properly
account for queueing behavior beyond a simple calculus based on average rates,
we advocate a system theoretic methodology for the capacity problem in finite
time and space regimes. This methodology also accounts for spatial correlations
arising in networks with CSMA/CA scheduling and it delivers rigorous
closed-form capacity results in terms of probability distributions. Unlike
numerous existing asymptotic results, subject to anecdotal practical concerns,
our transient one can be used in practical settings: for example, to compute
the time scales at which multi-hop routing is more advantageous than single-hop
routing.


title:
First integrals of ordinary difference equations which do not possess a
  variational formulation

abstract:
  The paper presents a new method for finding first integrals of ordinary
difference equations which do not possess Lagrangians, nor Hamiltonians. As an
example we solve a third order nonlinear ordinary differential equation and its
invariant discretization using three first integrals obtained using this
method.


title:
Super-Weyl anomalies in N=2 supergravity and (non)local effective
  actions

abstract:
  Using the formulation for N=2 conformal supergravity in SU(2) superspace, we
define super-Weyl (or superconformal) anomalies and construct two types of
nonlocal effective actions that generate these anomalies. We also present the
local Wess-Zumino action for spontaneously broken N=2 superconformal symmetry,
with the Goldstone supermultiplet identified with a reduced chiral superfield
containing the dilaton and the axion among its components.


title: Discontinuity relations for the AdS(4)/CFT(3) correspondence

abstract:
  We study in detail the analytic properties of the Thermodynamic Bethe Ansatz
(TBA) equations for the anomalous dimensions of composite operators in the
planar limit of the 3D N=6 superconformal Chern-Simons gauge theory and derive
functional relations for the jump discontinuities across the branch cuts in the
complex rapidity plane. These relations encode the analytic structure of the Y
functions and are extremely similar to the ones obtained for the
previously-studied AdS(5)/CFT(4) case. Together with the Y-system and more
basic analyticity conditions, they are completely equivalent to the TBA
equations. We expect these results to be useful to derive alternative nonlinear
integral equations for the AdS(4)/CFT(3) spectrum.


title:
Effect of surface hydrogen on the anomalous surface segregation behavior
  of Cr in Fe-rich Fe-Cr alloys

abstract:
  The segregation behavior of Cr in dilute Fe-Cr alloys is known to be
anomalous since the main barrier for surface segregation of Cr in these alloys
arises not from the topmost surface layer but from the subsurface layer where
the solution energy of Cr is much more endothermic as compared to the topmost
surface layer. The Fe-Cr alloys are candidate structural materials for the new
generation of nuclear reactors. The surfaces of these alloys will be exposed to
hydrogen or its isotopes in these reactors, and although hydrogen is soluble
neither in Fe nor in Fe-Cr alloys, it is known that the adsorption energy of
hydrogen on the surface of iron is not only exothermic but relatively large.
This clearly raises the question of the effect of the hydrogen adsorbed on the
surface of iron on the segregation behavior of chromium towards the surface of
iron. In this paper we show, on the basis of our ab initio density functional
theory calculations, that the presence of hydrogen on the surface of iron leads
to a considerably reduced barrier for Cr segregation to both the topmost
surface layer and the subsurface layer, but the subsurface layer still controls
the barrier for surface segregation. This reduction in the barrier for surface
segregation is due to the nature of the Cr-H couple that acts in a complex and
synergistic manner. The presence of Cr enhances the exothermic nature of
hydrogen adsorption that in turn leads to a reduced barrier for surface
segregation. These results should be included in the multiscale modeling of
Fe-Cr alloys.


title: Searching for solar-like oscillations in the delta Scuti star rho Puppis

abstract:
  Despite the shallow convective envelopes of delta Scuti pulsators, solar-like
oscillations are theoretically predicted to be excited in those stars as well.
To search for such stochastic oscillations we organised a spectroscopic
multi-site campaign for the bright, metal-rich delta Sct star rho Puppis. We
obtained a total of 2763 high-resolution spectra using four telescopes. We
discuss the reduction and analysis with the iodine cell technique, developed
for searching for low-amplitude radial velocity variations, in the presence of
high-amplitude variability. Furthermore, we have determined the angular
diameter of rho Puppis to be 1.68 \pm 0.03 mas, translating into a radius of
3.52 \pm 0.07Rsun. Using this value, the frequency of maximum power of possible
solar-like oscillations, is expected at ~43 \pm 2 c/d (498 \pm 23 muHz). The
dominant delta Scuti-type pulsation mode of rho Puppis is known to be the
radial fundamental mode which allows us to determine the mean density of the
star, and therefore an expected large frequency separation of 2.73 c/d (31.6
muHz). We conclude that 1) the radial velocity amplitudes of the delta Scuti
pulsations are different for different spectral lines; 2) we can exclude
solar-like oscillations to be present in rho Puppis with an amplitude per
radial mode larger than 0.5 m/s.


title:
Improvement of two-way continuous-variable quantum key distribution
  using optical amplifiers

abstract:
  The imperfections of a receiver's detector affect the performance of two-way
continuous-variable quantum key distribution protocols and are difficult to
adjust in practical situations. We propose a method to improve the performance
of two-way continuous-variable quantum key distribution by adding a
parameter-adjustable optical amplifier at the receiver. A security analysis is
derived against a two-mode collective entangling cloner attack. Our simulations
show that the proposed method can improve the performance of protocols as long
as the inherent noise of the amplifier is lower than a critical value, defined
as the tolerable amplifier noise. Furthermore, the optimal performance can
approach the scenario where a perfect detector is used.


title:
Localized exact solutions of $\mathcal{PT}$ symmetric nonlinear
  Schr\"odinger equation with space and time modulated nonlinearities

abstract:
  Using canonical transformations we obtain localized (in space) exact
solutions of the nonlinear Schr\"odinger equation (NLSE) with space and time
modulated nonlinearity and in the presence of an external potential depending
on space and time. In particular we obtain exact solutions of NLSE in the
presence of a number of non Hermitian $\mathcal{PT}$ symmetric external
potentials.


title:
Fluid/Gravity Correspondence, Second Order Transport and Gravitational
  Anomaly

abstract:
  We study the transport properties of a relativistic fluid affected by chiral
and gauge-gravitational anomalies. The computation is performed in the
framework of the fluid/gravity correspondence for a 5 dim holographic model
with Chern-Simons terms in the action. We find new anomalous and non anomalous
transport coefficients, as well as new contributions to the existing ones
coming from the mixed gauge-gravitational anomaly. Consequences for the shear
waves dispersion relation are analyzed.


title:
A microscopic model beyond mean-field: from giant resonances properties
  to the fit of new effective interactions

abstract:
  A completely microscopic beyond mean-field approach has been elaborated to
overcome some intrinsic limitations of self-consistent mean-field schemes
applied to nuclear systems, such as the incapability to produce some properties
of single-particle states (e.g. spectroscopic factors), as well as of
collective states (e.g. their damping width and their gamma decay to the ground
state or to low lying states). Since commonly used effective interactions are
fitted at the mean-field level, one should aim at refitting them including the
desired beyond mean-field contributions in the refitting procedure. If
zero-range interactions are used, divergences arise. We present some steps
towards the refitting of Skyrme interactions, for its application in finite
nuclei.


title:
The XMM-Newton survey of the Small Magellanic Cloud: The X-ray
  point-source catalogue

abstract:
  Local-Group galaxies provide access to samples of X-ray source populations of
whole galaxies. The XMM-Newton survey of the Small Magellanic Cloud (SMC)
completely covers the bar and eastern wing with a 5.6 deg^2 area in the
(0.2-12.0) keV band. To characterise the X-ray sources in the SMC field, we
created a catalogue of point sources and sources with moderate extent. Sources
with high extent (>40") have been presented in a companion paper. We searched
for point sources in the EPIC images using sliding-box and maximum-likelihood
techniques and classified the sources using hardness ratios, X-ray variability,
and their multi-wavelength properties. The catalogue comprises 3053 unique
X-ray sources with a median position uncertainty of 1.3" down to a flux limit
for point sources of ~10^-14 erg cm^-2 s^-1 in the (0.2-4.5) keV band,
corresponding to 5x10^33 erg s^-1 for sources in the SMC. We discuss
statistical properties, like the spatial distribution, X-ray colour diagrams,
luminosity functions, and time variability. We identified 49 SMC high-mass
X-ray binaries (HMXB), four super-soft X-ray sources (SSS), 34 foreground
stars, and 72 active galactic nuclei (AGN) behind the SMC. In addition, we
found candidates for SMC HMXBs (45) and faint SSSs (8) as well as AGN (2092)
and galaxy clusters (13). We present the most up-to-date catalogue of the X-ray
source population in the SMC field. In particular, the known population of
X-ray binaries is greatly increased. We find that the bright-end slope of the
luminosity function of Be/X-ray binaries significantly deviates from the
expected universal high-mass X-ray binary luminosity function.


title:
Observation of a resonance in $B^+ \to K^+ \mu^+\mu^-$ decays at low
  recoil

abstract:
  A broad peaking structure is observed in the dimuon spectrum of $B^+ \to K^+
\mu^+\mu^-$ decays in the kinematic region where the kaon has a low recoil
against the dimuon system. The structure is consistent with interference
between the $B^+ \to K^+ \mu^+\mu^-$ decay and a resonance and has a
statistical significance exceeding six standard deviations. The mean and width
of the resonance are measured to be $4191^{+9}_{-8}\mathrm{\,Me\kern -0.1em
V/}c^2$ and $65^{+22}_{-16}\mathrm{\,Me\kern -0.1em V/}c^2$, respectively,
where the uncertainties include statistical and systematic contributions. These
measurements are compatible with the properties of the $\psi(4160)$ meson.
First observations of both the decay $B^+ \to \psi(4160) K^+$ and the
subsequent decay $\psi(4160) \to \mu^+\mu^-$ are reported. The resonant decay
and the interference contribution make up 20\,% of the yield in the low recoil
region, which is larger than theoretical estimates.


title: Long-lived PeV-EeV Neutrinos from GRB Blastwave

abstract:
  Long duration gamma-ray bursts are powerful sources that can accelerate
particles to ultra-high energies. Acceleration of protons in the forward shock
of the highly relativistic GRB blastwave allows PeV--EeV neutrino production by
photopion interactions of ultra-high energy protons with X-ray to optical
photons of the GRB afterglow emission. Four different blastwave evolution
scenarios are considered: adiabatic and fully radiative blastwaves in a
constant density circumburst medium and in a wind environment with the particle
density in the wind decreasing inversley proportional to the square of the
radius from the center of the burst. The duration of the neutrino flux depends
on the evolution of the blastwave, and can last up to a day in the case of an
adibatic blastwave in a constant density medium. Neutrino fluxes from the three
other blastwave evolution scenarios are also calculated. Diffuse neutrino
fluxes calculated using the observed rate of long-duration GRBs are consistent
with the recent IceCube upper limit on the prompt GRB neutrino flux below PeV.
The diffuse neutrino flux needed to explain the two neutrino events at PeV
energies recently detected by IceCube can partially come from the presented GRB
blastwave diffuse fluxes. Future observations by IceCube and upcoming huge
radio Askaryan experiments will be able to probe the flux models presented here
or constrain the GRB blastwave properties.


title: Context-aware QR-codes

abstract:
  This paper describes a new model for presenting local information based on
the network proximity. We present a novelty mobile mashup which combines Wi-Fi
proximity measurements with QR-codes. Our mobile mashup automatically adds
context information the content presented by QR-codes. It simplifies the
deployment schemes and allows to use unified presentation for all data points,
for example. This paper describes how to combine QR-codes and network proximity
information.


title: Accurate Atom Counting in Mesoscopic Ensembles

abstract:
  Many cold atom experiments rely on precise atom number detection, especially
in the context of quantum-enhanced metrology where effects at the single
particle level are important. Here, we investigate the limits of atom number
counting via resonant fluorescence detection for mesoscopic samples of trapped
atoms. We characterize the precision of these fluorescence measurements
beginning from the single-atom level up to more than one thousand. By
investigating the primary noise sources, we obtain single-atom resolution for
atom numbers as high as 1200. This capability is an essential prerequisite for
future experiments with highly entangled states of mesoscopic atomic ensembles.


title: Pair-excitation energetics of highly correlated many-body states

abstract:
  A microscopic approach is developed to determine the excitation energetics of
highly correlated quasi-particles in optically excited semiconductors based
entirely on a pair-correlation function input. For this purpose, the Wannier
equation is generalized to compute the energy per excited electron-hole pair of
a many-body state probed by a weak pair excitation. The scheme is verified for
the degenerate Fermi gas and incoherent excitons. In a certain range of
experimentally accessible parameters, a new stable quasi-particle state is
predicted which consists of four to six electron-hole pairs forming a liquid
droplet of fixed radius. The energetics and pair-correlation features of these
"quantum droplets" are analyzed.


title:
Generalisation of Levine's prediction for the distribution of freezing
  temperatures of droplets: A general singular model for ice nucleation

abstract:
  Models without an explicit time dependence, called singular models, are
widely used for fitting the distribution of temperatures at which water
droplets freeze. In 1950 Levine developed the original singular model. His key
assumption was that each droplet contained many nucleation sites, and that
freezing occurred due to the nucleation site with the highest freezing
temperature. The fact that freezing occurs due to the maximum value out of
large number of nucleation temperatures, means that we can apply the results of
what is called extreme-value statistics. This is the statistics of the extreme,
i.e., maximum or minimum, value of a large number of random variables. Here we
use the results of extreme-value statistics to show that we can generalise
Levine's model to produce the most general singular model possible. We show
that when a singular model is a good approximation, the distribution of
freezing temperatures should always be given by what is called the generalised
extreme-value distribution. In addition, we also show that the distribution of
freezing temperatures for droplets of onesize, can be used to make predictions
for the scaling of the median nucleation temperature with droplet size, and
vice versa.


title:
Collider signatures of a light NMSSM pseudoscalar in neutralino decays
  in the light of LHC results

abstract:
  We investigate signatures induced by a very light pseudoscalar Higgs in
neutralino decays in the Next-to-Minimal Supersymmetric Standard Model (NMSSM)
and determine their observability at the LHC. We concentrate on scenarios which
feature two light scalar Higgs bosons (one of them is SM-like with a mass of
125 GeV and a singlet-like lighter one) with a very light (singlet-like)
pseudoscalar Higgs in the mass range 2m_tau < m_a1 < 2m_b. We consider
neutralino-chargino pair production and the subsequent decay X_{2,3}-> X_1 a1,
which leads to topologies involving multi-leptons and missing transverse
energy. We determine a set of selection cuts that can effectively isolate the
signal from backgrounds of the Standard Model or the Minimal Supersymmetric
Standard Model. We also exemplify the procedure with a set of benchmark points,
for which we compute the expected number of events and signal strength for LHC
with 8 TeV center of mass energy. We show that this signal can already be
probed for some points in the NMSSM parameter space.


title: Survey on Positioning System: Sampling methods

abstract:
  Millimeter-accuracy Ultra-Wideband (UWB) positioning systems using the Time
Difference Of Arrival (TDOA) algorithm are able to be utilized in military and
many other important applications. Previous research on UWB positioning system
has achieved up to mm or sub-mm accuracy. However, one bottleneck in UWB system
is at sampling high resolution UWB signals, as well as high resolution timing
information. In this paper, UWB positioning systems are surveyed and we focus
on sampling methods for handling UWB signals. Among different sampling methods,
one traditional way is the sequential sampling method, which is not a real time
sampling method and blocks UWB positioning system to achieve higher precision.
Another way is by applying Compressed Sensing (CS) to UWB system for achieving
sub-mm positioning accuracy. In this paper, we compare different TDOA-based UWB
systems with different sampling methods. In particular, several CS-UWB
algorithms for UWB signal reconstruction are compared in terms of positioning
accuracy. Simulation results in 2D and 3D experiments demonstrate performance
of different algorithms including typical BCS, OMP and BP algorithms. CS-UWB is
also compared with UWB positioning system based on the sequential sampling
method.


title: Forecasting a Coronal Mass Ejection's Altered Trajectory: ForeCAT

abstract:
  To predict whether a coronal mass ejection (CME) will impact Earth, the
effects of the background on the CME's trajectory must be taken into account.
We develop a model, ForeCAT (Forecasting a CME's Altered Trajectory), of CME
deflection due to magnetic forces. ForeCAT includes CME expansion, a three-part
propagation model, and the effects of drag on the CME's deflection. Given the
background solar wind conditions, the launch site of the CME, and the
properties of the CME (mass, final propagation speed, initial radius, and
initial magnetic strength), ForeCAT predicts the deflection of the CME. Two
different magnetic backgrounds are considered: a scaled background based on
type II radio burst profiles and a Potential Field Source Surface (PFSS)
background. For a scaled background where the CME is launched from an active
region located between a CH and streamer region the strong magnetic gradients
cause a deflection of 8.1 degrees in latitude and 26.4 degrees in longitude for
a 1e15 g CME propagating out to 1 AU. Using the PFSS background, which captures
the variation of the streamer belt position with height, leads to a deflection
of 1.6 degrees in latitude and 4.1 degrees in longitude for the control case.
Varying the CME's input parameters within observed ranges leads to the majority
of CMEs reaching the streamer belt within the first few solar radii. For these
specific backgrounds, the streamer belt acts like a potential well that forces
the CME into an equilibrium angular position.


title:
Stratified critical points one the real Milnor fibre and
  integral-geometric formulas

abstract:
  Let $(X,0) \subset (\mathbb{R}^n,0)$ be the germ of a closed subanalytic set
and let $f$ and $g : (X,0) \rightarrow (\mathbb{R},0)$ be two subanalytic
functions. Under some conditions, we relate the critical points of $g$ on the
real Milnor fibre $X \cap f^{-1}(\delta) \cap B_\epsilon$, $0 <| \delta | \ll
\epsilon \ll 1$, to the topology of this fibre and other related subanalytic
sets. As an application, when $g$ is a generic linear function, we obtain an
"asymptotic" Gauss-Bonnet formula for the real Milnor fibre of $f$. From this
Gauss-Bonnet formula, we deduce "infinitesimal" linear kinematic formulas.


title:
Interplay between crystallization and glass transition in binary
  Lennard-Jones mixtures

abstract:
  In this work we explore the interplay between crystallization and glass
transition in different binary mixtures by changing their inter-species
interaction length and also the composition. We find that only those systems
which form bcc crystal in the equimolar mixture and whose global structure for
larger $x_A$ ($x_A=0.6$, where $x_A$ is the mole fraction of the bigger
particles) is a mixed fcc+bcc phase, do not crystallize at this higher
composition. However, the systems whose equimolar structure is a variant of fcc
(NaCl type crystal) and whose global structure at larger $x_A$ is a mixed
NaCl+fcc phase, crystallize easily to this mixed structure. We find that the
stability against crystallization of this "bcc zone" is due to the frustration
between the locally preferred structure (LPS) and the mixed bcc+fcc crystal.
Our study suggests that when the global structure is a mixed crystal where a
single species contributes to both the crystal forms and where the two crystal
forms have large difference in some order parameter related to that species
then this induces frustration between the LPS and the global structure. This
frustration makes the systems good glass former. When $x_A$ is further
increased ($0.70\leq x_A < 0.90$) the systems show a tendency towards mixed fcc
crystal formation. However, the "bcc zone" even for this higher composition is
found to be sitting at the bottom of a V shaped phase diagram formed by two
different variants of the fcc crystal structure, leading to its stability
against crystallization.


title:
Electronic origin of the anomalous segregation behavior of Cr in Fe-rich
  Fe-Cr alloys

abstract:
  The energy of segregation of Cr from the bulk to the topmost surface layer in
dilute Fe-Cr alloys is endothermic but small. On the other hand, the
segregation energy from the bulk to the subsurface layer is not only
endothermic but relatively large. Thus, the subsurface layer presents a huge
barrier, not only for the segregation of Cr from the bulk to the surface, but
also for its diffusion from the surface into the bulk. This means that the
topmost layer alone cannot be used to determine the barrier for Cr segregation
(the segregation energy), which is determined in these alloys by the subsurface
layer. We present the results of our ab initio electronic structure
calculations on the segregation of Cr as an impurity in Fe, which shed some
light on the origin of this anomalous behavior. We find that the interaction of
a Cr atom situated in the subsurface layer, in contrast to those in the other
layers, is quite complex with its nearest neighbor Fe atoms due to the
magnetism of both Fe and Cr, leading to a highly unfavorable electronic
structure. This in turn leads to a large endothermic energy of solution of Cr
in the subsurface layer. These results are important for a proper understanding
of the properties of the technologically important class of Fe-Cr steels with
low concentrations of chromium.


title: Current-induced spin wave excitation in Pt|YIG bilayer

abstract:
  We develop a self-consistent theory for current-induced spin wave excitations
in normal metal-magnetic insulator bilayer systems, thereby establishing the
relation between spin wave excitation and the experimentally controlled
parameters. We fully take into account the complex spin wave spectrum including
dipolar interactions and surface anisotropy as well as the spin-pumping at the
interface. Our results focus on the mode-dependent power close to the critical
currents for spin wave excitation. The major findings are (a) the spin transfer
torque can excite different spin-wave modes simultaneously; (b) spin pumping
counterbalances spin-transfer torque and affects the surface modes more than
the bulk modes; (c) spin pumping inhibits high frequency spin-wave modes,
thereby redshifting the excitation spectrum. We can get agreement with
experiments on yttrium iron garnet|platinum bilayers by postulating the
existence of surface anisotropy modes.


title: Reflection matrices from Hadamard-type Temperley-Lieb R-matrices

abstract:
  We classify non-operatorial matrices K solving Skylanin's quantum reflection
equation for all R-matrices obtained from the newly defined general rank- n
Hadamard type representations of the Temperley-Lieb algebra $TL_N(\sqrt n)$.
They are characterized by a universal set of algebraic equations in a specific
canonical basis uniquely defined from the "Master matrix" associated to the
chosen realization of Temperley-Lieb algebra


title: Search for R-parity violating Supersymmetry using the CMS detector

abstract:
  In this talk, the latest results from CMS on R-parity violating Supersymmetry
are reviewed. We present results using up to 20/fb of data from the 8 TeV LHC
run of 2012. Interpretations of the experimental results in terms of production
of squarks, gluinos, charginos, neutralinos, and sleptons within R-parity
violating susy models are presented.


title: The Isospin Asymmetry in Anomalous Fluid Dynamics

abstract:
  The dynamics of fluids in which the constituent particles carry nonabelian
charges can be described succinctly in terms of group-valued variables via a
generalization of the co-adjoint orbit action for particles. This formalism,
which is particularly suitable for incorporating anomalies, has previously been
used for the chiral magnetic and chiral vorticity effects. Here we consider the
similar effect for the isospin which corresponds to an angular asymmetry for
neutral pions.


title:
Characterization of initial fluctuations for the hydrodynamical
  description of heavy ion collisions

abstract:
  Event-by-event fluctuations in the initial conditions for a hydrodynamical
description of heavy-ion collisions are characterized. We propose a
Bessel-Fourier decomposition with respect to the azimuthal angle, the radius in
the transverse plane and rapidity. This allows for a complete characterization
of fluctuations in all hydrodynamical fields including energy density,
pressure, fluid velocity, shear stress and bulk viscous pressure. It has the
advantage that fluctuations can be ordered with respect to their wave length
and that they can be propagated mode-by-mode within the hydrodynamical
formalism. Event ensembles can then be characterized in terms of a functional
probability distribution. For the event ensemble of a Monte Carlo Glauber
model, we provide evidence that the latter is close to Gaussian form, thus
allowing for a particularly simple characterization of the event distribution.


title: Wi-Fi Offload: Tragedy of the Commons or Land of Milk and Honey?

abstract:
  Fueled by its recent success in provisioning on-site wireless Internet
access, Wi-Fi is currently perceived as the best positioned technology for
pervasive mobile macro network offloading. However, the broad transitions of
multiple collocated operators towards this new paradigm may result in fierce
competition for the common unlicensed spectrum at hand. In this light, our
paper game-theoretically dissects market convergence scenarios by assessing the
competition between providers in terms of network performance, capacity
constraints, cost reductions, and revenue prospects. We will closely compare
the prospects and strategic positioning of fixed line operators offering Wi-Fi
services with respect to competing mobile network operators utilizing
unlicensed spectrum. Our results highlight important dependencies upon
inter-operator collaboration models, and more importantly, upon the ratio
between backhaul and Wi-Fi access bit-rates. Furthermore, our investigation of
medium- to long-term convergence scenarios indicates that a rethinking of
control measures targeting the large-scale monetization of unlicensed spectrum
may be required, as otherwise the used free bands may become subject to
tragedy-of-commons type of problems.


title: Fermion effective dispersion relation for z=2 Lifshitz QED

abstract:
  We study consequences of Lorentz symmetry violation in a z=2 Lifshitz
extension of QED in 3+1 dimensions, and we discuss non-trivial effects of
quantization. Because of the specific power of space momentum in propagators of
the model, dimensional regularization leads to an unusual interpretation of
loop integrals, which are finite even when the space dimension goes to the
integer 3. We check the consistency of the approach by calculating the
(vanishing) corrections to the photon mass and the IR-divergence-free
corrections to the dispersion relation for massless fermions.


title: On the Gauge-invariant Functional Measure for Gauge Fields on CP^2

abstract:
  We introduce a general parametrization for nonabelian gauge fields on the
four-dimensional space ${\mathbb{CP}}^2$. The volume element for the
gauge-orbit space or the space of physical configurations is then investigated.
The leading divergence in this volume element is obtained in terms of a higher
dimensional Wess-Zumino-Witten action, which has previously been studied in the
context of K\"ahler-Chern-Simons theories. This term, it is argued, implies
that one needs to introduce a dimensional parameter to specify the integration
measure, a step which is a nonperturbative version of the well-known
dimensional transmutation in four-dimensional gauge theories.


title:
Association schemes, non-commutative polynomial concentration, and
  sum-of-squares lower bounds for planted clique

abstract:
  Finding cliques in random graphs and the closely related "planted" clique
variant, where a clique of size t is planted in a random G(n,1/2) graph, have
been the focus of substantial study in algorithm design. Despite much effort,
the best known polynomial-time algorithms only solve the problem for t =
Theta(sqrt(n)). Here we show that beating sqrt(n) would require substantially
new algorithmic ideas, by proving a lower bound for the problem in the
sum-of-squares (or Lasserre) hierarchy, the most powerful class of
semi-definite programming algorithms we know of: r rounds of the sum-of-squares
hierarchy can only solve the planted clique for t > sqrt(n)/(C log n)^(r^2).
Previously, no nontrivial lower bounds were known. Our proof is formulated as a
degree lower bound in the Positivstellensatz algebraic proof system, which is
equivalent to the sum-of-squares hierarchy. The heart of our (average-case)
lower bound is a proof that a certain random matrix derived from the input
graph is (with high probability) positive semidefinite. Two ingredients play an
important role in this proof. The first is the classical theory of association
schemes, applied to the average and variance of that random matrix. The second
is a new large deviation inequality for matrix-valued polynomials. Our new tail
estimate seems to be of independent interest and may find other applications,
as it generalizes both the estimates on real-valued polynomials and on sums of
independent random matrices.


title:
Hydrogen accommodation in Zr second phase particles: Implications for H
  pick-up and hydriding of Zircaloy-2 and Zircaloy-4

abstract:
  Ab-initio computer simulations have been used to predict the energies
associated with the accommodation of H atoms at interstitial sites in {\alpha},
{\beta}-Zr and Zr.M intermetallics formed with common alloying additions (M =
Cr, Fe, Ni). Intermetallics that relate to the Zr2(Ni,Fe) second phase
particles (SPPs) found in Zircaloy-2 exhibit favourable solution enthalpies for
H. The intermetallic phases that relate to the Zr(Cr,Fe)2 SPPs, found
predominantly in Zircaloy-4, do not offer favourable sites for interstitial H.
It is proposed that Zr(Cr,Fe)2 particles may act as bridges for the migration
of H through the oxide layer, whilst the Zr2(Ni,Fe)-type particles will trap
the migrating H until these are dissolved or fully oxidised.


title: Hydrogen solubility in zirconium intermetallic second phase particles

abstract:
  The enthalpies of solution of H in Zr binary intermetallic compounds formed
with Cu, Cr, Fe, Mo, Ni, Nb, Sn and V were calculated by means of density
functional theory simulations and compared to that of H in {\alpha}-Zr. It is
predicted that all Zr-rich phases (formed with Cu, Fe, Ni and Sn), and those
phases formed with Nb and V, offer lower energy, more stable sites for H than
{\alpha}-Zr. Conversely, Mo and Cr containing phases do not provide
preferential solution sites for H. In all cases the most stable site for H are
those that offer the highest coordination fraction of Zr atoms. Often these are
four Zr tetrahedra but not always. Implications with respect to H-trapping
properties of commonly observed ternary phases such as Zr(Cr,Fe)2, Zr2(Fe,Ni)
and Zr(Nb,Fe)2 are also discussed.


title: Variability Time Scales of Long and Short GRBs

abstract:
  Gamma-ray bursts (GRB) are extremely energetic events and produce highly
diverse light curves. Light curves are believed to be resulting from internal
shocks reflecting the activities of the GRB central engine. Hence their
temporal studies can potentially lead to an understanding of the GRB central
engine and its evolution. The light curve variability time scale is an
interesting parameter which most models attribute to a physical origin e.g.,
central engine activity, clumpy circum-burst medium, or relativistic
turbulence. We develop a statistical method to estimate the GRB minimum
variability time scale (MVT) for long and short GRBs detected by GBM. We find
that the MVT of short bursts is distinctly shorter than that of long GRBs
supporting the possibility of a more compact central engine of the former. We
also find that MVT estimated by this method is consistent with the shortest
rise time of the fitted pulses. Hence we use the fitted pulse rise times to
study the evolution of burst variability time scale. Variability time coupled
with the highest energy photon detected in turn related to the minimum bulk
Lorentz factor of the relativistic shell emitted by the inner engine. %Using
this we relate the GRB spectral evolution to the evolution of the variability
time scale.


title:
Artin representations for GSp_4 attached to real analytic Siegel cusp
  forms of weight (2,1)

abstract:
  Let $F$ be a vector-valued real analytic Siegel cusp eigenform of weight
$(2,1)$ with the eigenvalues $-\frac 5{12}$ and 0 for the two generators of the
center of the algebra consisting of all $Sp_4(\R)$-invariant differential
operators on the Siegel upper half plane of degree 2. Under the assumptions (1)
the validity of the transfer of automorphic representations of $GSp_4$ to
$GL_4$; (2) the existence of mod $\ell$ Galois representation attached to $F$
and its lift to characteristic zero; (3) rationality of the space consisting of
any such $F$; and (4) the integrality of Hecke polynomials of $F$, we construct
a unique Artin representation of type $GSp_4$ associated to $F$. Several
examples which satisfy these assumptions are given by using various transfers
and automorphic descent.


title: Time-Varying Nuclear Decay Parameters and Dark Matter

abstract:
  Recently published data suggest a possible solar influence on some nuclear
decay rates, including evidence for an annual variation attributed to the
varying Earth-Sun distance. Here, we consider the possibility that the annual
signal seen by the DAMA collaboration, and interpreted by them as evidence for
dark matter, may in fact be due to the radioactive contaminant K-40, which is
known to be present in their detector. We also consider the possibility that
part of the DAMA signal may arise from relic big-bang neutrinos.


title: Packing Steiner Trees

abstract:
  Let $T$ be a distinguished subset of vertices in a graph $G$. A
$T$-\emph{Steiner tree} is a subgraph of $G$ that is a tree and that spans $T$.
Kriesell conjectured that $G$ contains $k$ pairwise edge-disjoint $T$-Steiner
trees provided that every edge-cut of $G$ that separates $T$ has size $\ge 2k$.
When $T=V(G)$ a $T$-Steiner tree is a spanning tree and the conjecture is a
consequence of a classic theorem due to Nash-Williams and Tutte. Lau proved
that Kriesell's conjecture holds when $2k$ is replaced by $24k$, and recently
West and Wu have lowered this value to $6.5k$. Our main result makes a further
improvement to $5k+4$.


title: Distributed Energy Trading: The Multiple-Microgrid Case

abstract:
  In this paper, a distributed convex optimization framework is developed for
energy trading between islanded microgrids. More specifically, the problem
consists of several islanded microgrids that exchange energy flows by means of
an arbitrary topology. Due to scalability issues and in order to safeguard
local information on cost functions, a subgradient-based cost minimization
algorithm is proposed that converges to the optimal solution in a practical
number of iterations and with a limited communication overhead. Furthermore,
this approach allows for a very intuitive economics interpretation that
explains the algorithm iterations in terms of "supply--demand model" and
"market clearing". Numerical results are given in terms of convergence rate of
the algorithm and attained costs for different network topologies.


title: Milli-interacting Dark Matter

abstract:
  We present a dark matter model reproducing well the results from DAMA/LIBRA
and CoGeNT and having no contradiction with the negative results from XENON100
and CDMS-II/Ge. Two new species of fermions F and G form hydrogen-like atoms
with standard atomic size through a dark U(1) gauge interaction carried out by
a dark massless photon. A Yukawa coupling between the nuclei F and neutral
scalar particles S induces an attractive shorter-range interaction. This dark
sector interacts with our standard particles because of the presence of two
mixings, a kinetic photon-dark photon mixing, and a mass {\sigma}-S mixing. The
dark atoms from the halo diffuse elastically in terrestrial matter until they
thermalize and then reach underground detectors with thermal energies, where
they form bound states with nuclei by radiative capture. This causes the
emission of photons that produce the signals observed by direct-search
experiments.