title:
Bayesian Estimation of White Matter Atlas from High Angular Resolution
  Diffusion Imaging

abstract:
  We present a Bayesian probabilistic model to estimate the brain white matter
atlas from high angular resolution diffusion imaging (HARDI) data. This model
incorporates a shape prior of the white matter anatomy and the likelihood of
individual observed HARDI datasets. We first assume that the atlas is generated
from a known hyperatlas through a flow of diffeomorphisms and its shape prior
can be constructed based on the framework of large deformation diffeomorphic
metric mapping (LDDMM). LDDMM characterizes a nonlinear diffeomorphic shape
space in a linear space of initial momentum uniquely determining diffeomorphic
geodesic flows from the hyperatlas. Therefore, the shape prior of the HARDI
atlas can be modeled using a centered Gaussian random field (GRF) model of the
initial momentum. In order to construct the likelihood of observed HARDI
datasets, it is necessary to study the diffeomorphic transformation of
individual observations relative to the atlas and the probabilistic
distribution of orientation distribution functions (ODFs). To this end, we
construct the likelihood related to the transformation using the same
construction as discussed for the shape prior of the atlas. The probabilistic
distribution of ODFs is then constructed based on the ODF Riemannian manifold.
We assume that the observed ODFs are generated by an exponential map of random
tangent vectors at the deformed atlas ODF. Hence, the likelihood of the ODFs
can be modeled using a GRF of their tangent vectors in the ODF Riemannian
manifold. We solve for the maximum a posteriori using the
Expectation-Maximization algorithm and derive the corresponding update
equations. Finally, we illustrate the HARDI atlas constructed based on a
Chinese aging cohort of 94 adults and compare it with that generated by
averaging the coefficients of spherical harmonics of the ODF across subjects.


title:
forqs: Forward-in-time Simulation of Recombination, Quantitative Traits,
  and Selection

abstract:
  forqs is a forward-in-time simulation of recombination, quantitative traits,
and selection. It was designed to investigate haplotype patterns resulting from
scenarios where substantial evolutionary change has taken place in a small
number of generations due to recombination and/or selection on polygenic
quantitative traits. forqs is implemented as a command- line C++ program.
Source code and binary executables for Linux, OSX, and Windows are freely
available under a permissive BSD license.


title: Hardness of decoding quantum stabilizer codes

abstract:
  In this article we address the computational hardness of optimally decoding a
quantum stabilizer code. Much like classical linear codes, errors are detected
by measuring certain check operators which yield an error syndrome, and the
decoding problem consists of determining the most likely recovery given the
syndrome. The corresponding classical problem is known to be NP-complete, and a
similar decoding problem for quantum codes is also known to be NP-complete.
However, this decoding strategy is not optimal in the quantum setting as it
does not take into account error degeneracy, which causes distinct errors to
have the same effect on the code. Here, we show that optimal decoding of
stabilizer codes is computationally much harder than optimal decoding of
classical linear codes, it is #P.


title:
The sharp threshold for maximum-size sum-free subsets in even-order
  abelian groups

abstract:
  We study sum-free sets in sparse random subsets of even order abelian groups.
In particular, we determine the sharp threshold for the following property: the
largest such set is contained in some maximum-size sum-free subset of the
group. This theorem extends recent work of Balogh, Morris and Samotij, who
resolved the case G = Z_{2n}, and who obtained a weaker threshold (up to a
constant factor) in general.


title: Comparison between Rigid and Overconvergent Cohomology with Coefficients

abstract:
  For a smooth scheme over a perfect field of characteristic p>0, we generalise
a definition of Bloch and introduce overconvergent de Rham-Witt connections.
This provides a tool to extend the comparison morphisms of Davis, Langer and
Zink between overconvergent de Rham-Witt cohomology and Monsky-Washnitzer
respectively rigid cohomology to coefficients.


title: Lorentz Transformation of Blackbody Radiation

abstract:
  We present a simple calculation of the Lorentz transformation of the spectral
distribution of blackbody radiation at temperature T. Here we emphasize that T
is the temperature in the blackbody rest frame and does not change. We thus
avoid the confused and confusing question of how temperature transforms. We
show by explicit calculation that at zero temperature the spectral distribution
is invariant. At finite temperature we find the well known result familiar in
discussions of the the 2.7! K cosmic radiation.


title: Buffer gas loaded magneto-optical traps for Yb, Tm, Er and Ho

abstract:
  Direct loading of lanthanide atoms into magneto-optical traps (MOTs) from a
very slow cryogenic buffer gas beam source is achieved, without the need for
laser slowing. The beam source has an average forward velocity of 60-70\,m/s
and a velocity half-width of ~35 m/s, which allows for direct MOT loading of
Yb, Tm, Er and Ho. Residual helium background gas originating from the beam
results in a maximum trap lifetime of about 80 ms (with Yb). The addition of a
single-frequency slowing laser applied to the Yb in the buffer gas beam
increases the number of trapped Yb atoms to 1.3(0.7) x 10^8 with a loading rate
of 2.0(1.0) x 10^10 atoms/s. Decay to metastable states is observed for all
trapped species and decay rates are measured. Extension of this approach to the
loading of molecules into a MOT is discussed.


title: Phase Retrieval from Coded Diffraction Patterns

abstract:
  This paper considers the question of recovering the phase of an object from
intensity-only measurements, a problem which naturally appears in X-ray
crystallography and related disciplines. We study a physically realistic setup
where one can modulate the signal of interest and then collect the intensity of
its diffraction pattern, each modulation thereby producing a sort of coded
diffraction pattern. We show that PhaseLift, a recent convex programming
technique, recovers the phase information exactly from a number of random
modulations, which is polylogarithmic in the number of unknowns. Numerical
experiments with noiseless and noisy data complement our theoretical analysis
and illustrate our approach.

categories: cs.IT math.FA math.IT math.NA math.OC math.ST stat.TH


title: On Global Solutions of a Zakharov type System

abstract:
  We consider a class of wave-Schroedinger systems with a Zakharov-Schulman
type coupling. This class of systems is indexed by a parameter gamma which
measures the strength of the null form in the nonlinearity of the wave
equation. The case gamma = 1 corresponds to the well-known Zakharov system,
while the case gamma = -1 corresponds to the Yukawa system. Here we show that
sufficiently smooth and localized Cauchy data lead to pointwise decaying global
solutions which scatter, for any gamma in (0,1].


title:
On the sensitivity of the GOES flare classification to properties of the
  electron beam in the thick target model

abstract:
  The collisional thick target model, wherein a large number of electrons are
accelerated down a flaring loop, can be used to explain many observed
properties of solar flares. In this study, we focus on the sensitivity of GOES
flare classification to the properties of the thick target model. Using a
hydrodynamic model with RHESSI-derived electron beam parameters, we explore the
effects of the beam energy flux (or total non-thermal energy), the cut-off
energy, and the spectral index of the electron distribution on the soft X-rays
(SXRs) observed by GOES. We conclude that (1) the GOES class is proportional to
the non-thermal energy $E^{\alpha}$ for $\alpha \approx 1.7$ in the low energy
passband (1-8 \AA) and $\approx 1.6$ in the high energy passband (0.5-4 \AA);
(2) the GOES class is only weakly dependent on the spectral index in both
passbands; (3) increases in the cut-off will increase the flux in the 0.5-4
\AA\ passband, but decrease the flux in the 1-8 \AA\ passband, while decreases
in the cut-off will cause a decrease in the 0.5-4 \AA\ passband and a slight
increase in the 1-8 \AA\ passband.


title:
Statistical mechanics of ideal gas in the presence of minimal length and
  maximal momentum

abstract:
  Various approaches to quantum gravity suggest that the fundamental volume of
the phase space of the given space for representative points, means !0, should
be modified. In this paper, we study the effects of this modification on the
thermodynamics of an ideal gas within the micro canonical ensemble. For this
end, we use a Generalized Uncertainty Principle (GUP) that admits both a
minimal measurable length and a maximal momentum. Using this GUP causes
decreasing the total number of the microstates of the system. In the first
step, we calculate these reductions for classical ideal gas, and in the second
step, we calculate these effects for ultra relativistic gas.


title: Asymptotic entanglement transformation between W and GHZ states

abstract:
  We investigate entanglement transformations with stochastic local operations
and classical communication (SLOCC) in an asymptotic setting using the concepts
of degeneration and border rank of tensors from algebraic complexity theory.
Results well-known in that field imply that GHZ states can be transformed into
W states at rate 1 for any number of parties. As a generalization, we find that
the asymptotic conversion rate from GHZ states to Dicke states is bounded as
the number of subsystems increase and the number of excitations is fixed. By
generalizing constructions of Coppersmith and Winograd and by using monotones
introduced by Strassen we also compute the conversion rate from W to GHZ
states.


title: Template iterations and maximal cofinitary groups

abstract:
  The main result of the present paper is that $\mathfrak a_g$, the minimal
size of maximal cofinitary group, can be of countable cofinality. To prove this
we define a natural poset for adding a maximal cofinitary group of a given
cardinality, which enjoys certain combinatorial properties allowing it to be
used within a similar template forcing construction. Additionally we obtain
that $\mathfrak a_p$, the minimal size of a maximal family of almost disjoint
permutations, and $\mathfrak a_e$, the minimal size of a maximal eventually
different family, can be of countable cofinality.


title: Hard thermal loops in static background fields

abstract:
  We discuss the high temperature behavior of retarded thermal loops in static
external fields. We employ an analytic continuation of the imaginary time
formalism and use a spectral representation of the thermal amplitudes. We show
that, to all orders, the leading contributions of static hard thermal loops can
be directly obtained by evaluating them at zero external energies and momenta.


title:
Study of the threshold line between macroscopic and bulk behaviors for
  homogeneous type II superconductors

abstract:
  In this work we solved the time dependent Ginzburg-Landau equations to
simulate homogeneous superconducting samples with square geometry for several
lateral sizes. As a result of such simulations we notice that in the Meissner
state, when the vortices do not penetrate the superconductor, the response of
small samples are not coincident with that expected for the bulk ones, i.e.,
$4\pi M=-H$. Thus, we focused our analyzes on the way which the $M(H)$ curves
approximate from the characteristic curve of bulk superconductors. With such
study, we built a diagram of the size of the sample as a function of the
temperature which indicates a threshold line between macroscopic and bulk
behaviors.


title:
A low complexity approach of combining cooperative diversity and
  multiuser diversity in multiuser cooperative networks

abstract:
  In this paper, we investigate the scheduling scheme to combine cooperative
diversity (CD) and multiuser diversity (MUD) in multiuser cooperative networks
under the time resource allocation (TRA) framework in which the whole
transmission is divided into two phases: the broadcast phase and the relay
phase. The broadcast phase is for direct transmission whereas the relay phase
is for relay transmission. Based on this TRA framework, a user selection based
low complexity relay protocol (US-LCRP) is proposed to combine CD and MUD. In
each time slot (TS) of the broadcast phase, a "best" user is selected for
transmission in order to obtain MUD. In the relay phase, the relays forward the
messages of some specific users in a fixed order and then invoke the limited
feedback information to achieve CD. We demonstrate that the
diversity-multiplexing tradeoff (DMT) of the US-LCRP is superior to that of the
existing schemes, where more TSs are allocated for direct transmission in order
to jointly exploit CD and MUD. Our analytical and numerical results show that
the US-LCRP constitutes a more efficient resource utilization approach than the
existing schemes. Additionally, the US-LCRP can be implemented with low
complexity because only the direct links' channel state information (CSI) is
estimated during the whole transmission.


title: The Boulware-Deser mode in Zwei-Dreibein gravity

abstract:
  Massive gravity in three dimensions accepts several different formulations.
Recently, the 3-dimensional bigravity dRGT model in first order form,
Zwei-Dreibein gravity, was considered by Bergshoeff {\it et al.} and it was
argued that the Boulware-Deser mode is killed by extra constraints. We revisit
this assertion and conclude that there are sectors on the space of initial
conditions, or subsets of the most general such model, where this mode is
absent. But, generically, the theory does carry 3 degrees of freedom and thus
the Boulware-Deser mode is still active. Our results also sheds light on the
equivalence between metric and vierbein formulations of dRGT model.


title: $\Sigma^1_2$ and $\Pi^1_1$ mad families

abstract:
  We answer in the affirmative the following question of J\"org Brendle: If
there is a $\Sigma^1_2$ mad family, is there then a $\Pi^1_1$ mad family?


title: On a category of $gl_{\infty}$-modules

abstract:
  We study a particular category ${\cal{C}}$ of $\gl_{\infty}$-modules and a
subcategory ${\cal{C}}_{int}$ of integrable $\gl_{\infty}$-modules. As the main
results, we classify the irreducible modules in these two categories and we
show that every module in category ${\cal{C}}_{int}$ is semi-simple.
Furthermore, we determine the decomposition of the tensor products of
irreducible modules in category ${\cal{C}}_{int}$.


title: Towards (1+\epsilon)-Approximate Flow Sparsifiers

abstract:
  A useful approach to "compress" a large network $G$ is to represent it with a
{\em flow-sparsifier}, i.e., a small network $H$ that supports the same flows
as $G$, up to a factor $q \geq 1$ called the quality of sparsifier.
Specifically, we assume the network $G$ contains a set of $k$ terminals $T$,
shared with the network $H$, i.e., $T\subseteq V(G)\cap V(H)$, and we want $H$
to preserve all multicommodity flows that can be routed between the terminals
$T$. The challenge is to construct $H$ that is small.
  These questions have received a lot of attention in recent years, leading to
some known tradeoffs between the sparsifier's quality $q$ and its size
$|V(H)|$. Nevertheless, it remains an outstanding question whether every $G$
admits a flow-sparsifier $H$ with quality $q=1+\epsilon$, or even $q=O(1)$, and
size $|V(H)|\leq f(k,\epsilon)$ (in particular, independent of $|V(G)|$ and the
edge capacities). Making a first step in this direction, we present new
constructions for several scenarios:
  * Our main result is that for quasi-bipartite networks $G$, one can construct
a $(1+\epsilon)$-flow-sparsifier of size $\poly(k/\eps)$. In contrast, exact
($q=1$) sparsifiers for this family of networks are known to require size
$2^{\Omega(k)}$.
  * For networks $G$ of bounded treewidth $w$, we construct a flow-sparsifier
with quality $q=O(\log w / \log\log w)$ and size $O(w\cdot \poly(k))$.
  * For general networks $G$, we construct a {\em sketch} $sk(G)$, that stores
all the feasible multicommodity flows up to factor $q=1+\eps$, and its size
(storage requirement) is $f(k,\epsilon)$.


title: Bethe vectors of quantum integrable models based on Uq(gl(N))

abstract:
  We study quantum Uq(gl(N)) integrable models solvable by the nested algebraic
Bethe ansatz. Different formulas are given for the right and left universal
off-shell nested Bethe vectors. It is shown that these formulas can be related
by certain morphisms of the positive Borel subalgebra in Uq(gl(N)) into
analogous subalgebra in Uq'(gl(N)), with q'=1/q.


title:
Neutrinoless double beta decay of 48Ca in the shell model: Closure
  versus nonclosure approximation

abstract:
  Neutrinoless double-beta decay is a unique process that could reveal physics
beyond the Standard Model. Essential ingredients in the analysis of
neutrinoless double-beta rates are the associated nuclear matrix elements. Most
of the approaches used to calculate these matrix elements rely on the closure
approximation. Here we analyze the light neutrino-exchange matrix elements of
48Ca neutrinoless double-beta decay and test the closure approximation in a
shell-model approach. We calculate the neutrinoless double-beta nuclear matrix
elements for 48Ca using both the closure approximation and a nonclosure
approach, and we estimate the uncertainties associated with the closure
approximation. We demonstrate that the nonclosure approach has excellent
convergence properties which allow us to avoid unmanageable computational cost.
Combining the nonclosure and closure approaches we propose a new method of
calculation for neutrinoless double-beta decay rates which can be applied to
the neutrinoless double-beta decay rates of heavy nuclei, such as 76Ge or 82Se.


title:
An Empirical Connection between the UV Color of Early Type Galaxies and
  the Stellar Initial Mass Function

abstract:
  Using new UV magnitudes for a sample of early-type galaxies, ETGs, with
published stellar mass-to-light ratios, Upsilon_*, we find a correlation
between UV color and Upsilon_* that is tighter than those previously identified
between Upsilon_* and either the central stellar velocity dispersion,
metallicity, or alpha enhancement. The sense of the correlation is that
galaxies with larger Upsilon_* are bluer in the UV. We conjecture that
differences in the lower mass end of the stellar initial mass function, IMF,
are related to the nature of the extreme horizontal branch populations that are
generally responsible for the UV flux in ETGs. If so, then UV color can be used
to identify ETGs with particular IMF properties and to estimate Upsilon_*.


title: A Q-Continuum of Off-Shell Supermultiplets

abstract:
  We explore a continuum of observably and usefully inequivalent,
finite-dimensional off-shell representations of worldline N=4-extended
supersymmetry, differing from one another only in the value of a "tuning
parameter." Their dynamics turns out to be nontrivial already when restricting
to just bilinear Lagrangians. In particular, we find a 34-parameter family of
bilinear Lagrangians that couple two differently "tuned" of these
supermultiplets to each other and to external magnetic fields, where the
explicit dependence on the tuning parameters cannot be removed by any field
redefinition and so is observable.


title:
The 3 x 3 x 3 hyperdeterminant as a polynomial in the fundamental
  invariants for SL(3,C) x SL(3,C) x SL(3,C)

abstract:
  We briefly review previous work on the invariant theory of 3 x 3 x 3 arrays.
We then recall how to generate arrays of arbitrary size m_1 x ... x m_k with
hyperdeterminant 0. Our main result is an explicit formula for the 3 x 3 x 3
hyperdeterminant as a polynomial in the fundamental invariants of degrees 6, 9
and 12 for the action of the Lie group SL(3,C) x SL(3,C) x SL(3,C). We apply
our calculations to Nurmiev's classification of normal forms for 3 x 3 x 3
arrays.


title: On General Off-Shell Representations of Worldline (1D) Supersymmetry

abstract:
  Every finite-dimensional unitary representation of the N-extended worldline
supersymmetry without central charges may be obtained by a sequence of
differential transformations from a direct sum of minimal Adinkras, simple
supermultiplets that are identifiable with representations of the Clifford
algebra. The data specifying this procedure is a sequence of subspaces of the
direct sum of Adinkras, which then opens an avenue for classification of the
continuum of so constructed off-shell supermultiplets.


title:
Closed Superstring Amplitudes, Single-Valued Multiple Zeta Values and
  Deligne Associator

abstract:
  We revisit the tree-level closed superstring amplitude and identify its
alpha'-expansion as series with single-valued multiple zeta values as
coefficients. The latter represent a subclass of multiple zeta values
originating from single-valued multiple polylogarithms at unity. Moreover, the
alpha'-expansion of the closed superstring amplitude can be cast into the same
algebraic form as the open superstring amplitude: the closed superstring
amplitude essentially is the single-valued version of the open superstring
amplitude. This fact points into a deeper connection between gauge and gravity
amplitudes than what is implied by Kawai-Lewellen-Tye relations. Furthermore,
we argue, that the Deligne associator carries the relevant information on the
closed superstring amplitude. In particular, we give an explicit representation
of the Deligne associator in terms of Gamma functions modulo squares of
commutators of the underlying Lie algebra. This form of the associator can be
interpreted as the four-point closed superstring amplitude.


title: Quantum Error Correction for Metrology

abstract:
  We propose and analyze a new approach based on quantum error correction (QEC)
to improve quantum metrology in the presence of noise. We identify the
conditions under which QEC allows one to improve the signal-to-noise ratio in
quantum-limited measurements, and we demonstrate that it enables, in certain
situations, Heisenberg-limited sensitivity. We discuss specific applications to
nanoscale sensing using nitrogen-vacancy centers in diamond in which QEC can
significantly improve the measurement sensitivity and bandwidth under realistic
experimental conditions.


title: Distances and moments of inertia of Fermi Pulsars

abstract:
  Measurement of distances and moments of inertia of pulsars must be useful,
for instance, for three-dimensional mapping of the dispersion and rotation
measures, constraining the nuclear equation of state, etc. The distances and
moments of inertia can be measured by fitting the gamma-ray lightcurves of
pulsars, because the gamma-ray emission seems to be governed by easily
calculable physics. The (first-principle) theoretical lightcurves have been
computed only for weak pulsars (pair production near the light cylinder much
smaller than Goldreich-Julian [1] per rotation), and at insufficient accuracy;
but, since this computation has been done by a self-taught numericist, it must
be possible to improve the theoretical accuracy for weak pulsars, and also to
extend the computation to non-weak pulsars.
  To invite the computational effort of better-equipped researchers, we
describe an (entirely obvious) procedure for measuring the distances and
moments of inertia for weak pulsars.


title: Optimal bounds for semi-honest quantum oblivious transfer

abstract:
  Oblivious transfer is a fundamental cryptographic primitive in which Bob
transfers one of two bits to Alice in such a way that Bob cannot know which of
the two bits Alice has learned. We present an optimal security bound for
quantum oblivious transfer protocols under a natural and demanding definition
of what it means for Alice to cheat. Our lower bound is a smooth tradeoff
between the probability B with which Bob can guess Alice's bit choice and the
probability A with which Alice can guess both of Bob's bits given that she
learns one of the bits with certainty. We prove that 2B + A is greater than or
equal to 2 in any quantum protocol for oblivious transfer, from which it
follows that one of the two parties must be able to cheat with probability at
least 2/3. We prove that this bound is optimal by exhibiting a family of
protocols whose cheating probabilities can be made arbitrarily close to any
point on the tradeoff curve.


title: Reconstructing top quark-antiquark events with one lost jet

abstract:
  We present a technique for reconstructing the kinematics of pair-produced top
quarks that decay to a charged lepton, a neutrino and four final state quarks
in the subset of events where only three jets are reconstructed. We present a
figure of merit that allows for a fair comparison of reconstruction algorithms
without requiring their calibration. The new reconstruction of events with only
three jets is fully competitive with the full reconstruction typically used for
four jet events.


title:
Neutron spectroscopic study of crystal field excitations in Tb2Ti2O7 and
  Tb2Sn2O7

abstract:
  We present time-of-flight inelastic neutron scattering measurements at low
temperature on powder samples of the magnetic pyrochlore oxides Tb2Ti2O7 and
Tb2Sn2O7. These two materials possess related, but different ground states,
with Tb2Sn2O7 displaying "soft" spin ice order below Tn~0.87 K, while Tb2Ti2O7
enters a hybrid, glassy spin ice state below Tg~0.2 K. Our neutron
measurements, performed at T=1.5 K and 30 K, probe the crystal field states
associated with the J=6 states of Tb3+ within the appropriate Fd\bar{3}m
pyrochlore environment. These crystal field states determine the size and
anisotropy of the Tb3+ magnetic moment in each material's ground state,
information that is an essential starting point for any description of the
low-temperature phase behavior and spin dynamics in Tb2Ti2O7 and Tb2Sn2O7.
While these two materials have much in common, the cubic stanate lattice is
expanded compared to the cubic titanate lattice. As our measurements show, this
translates into a factor of ~2 increase in the crystal field bandwidth of the
2J+1=13 states in Tb2Ti2O7 compared with Tb2Sn2O7. Our results are consistent
with previous measurements on crystal field states in Tb2Sn2O7, wherein the
ground state doublet corresponds primarily to m_J=|\pm 5> and the first excited
state doublet to mJ=|\pm 4>. In contrast, our results on Tb2Ti2O7 differ
markedly from earlier studies, showing that the ground state doublet
corresponds to a significant mixture of mJ=|\pm 5>, |\mp 4>, and |\pm 2>, while
the first excited state doublet corresponds to a mixture of mJ=|\pm 4>, |\mp
5>, and |\pm 1>. We discuss these results in the context of proposed mechanisms
for the failure of Tb2Ti2O7 to develop conventional long-range order down to 50
mK.


title: On Negacyclic MDS-Convolutional Codes

abstract:
  New families of classical and quantum optimal negacyclic convolutional codes
are constructed in this paper. This optimality is in the sense that they attain
the classical (quantum) generalized Singleton bound. The constructions
presented in this paper are performed algebraically and not by computational
search.


title:
Relativistic scalar fields and the quasi-static approximation in
  theories of modified gravity

abstract:
  Relativistic scalar fields are ubiquitous in modified theories of gravity. An
important tool in understanding their impact on structure formation, especially
in the context of N-body simulations, is the quasi-static approximation in
which the time evolution of perturbations in the scalar fields is discarded. We
show that this approximation must be used with some care by studying linearly
perturbed scalar field cosmologies and quantifying the errors that arise from
taking the quasi-static limit. We focus on f(R) and chameleon models and link
the accuracy of the quasi-static approximation to the fast/slow-roll behaviour
of the background and its proximity to {\Lambda}CDM. Investigating a large
range of scales, from super- to sub-horizon, we find that slow-rolling
({\Lambda}CDM-like) backgrounds generically result in good quasi-static
behaviour, even on (super-)horizon scales. We also discuss how the
approximation might affect studying the non-linear growth of structure in
numerical N-body simulations.


title: A 500 pc filamentary gas wisp in the disk of the Milky Way

abstract:
  Star formation occurs in molecular gas. In previous studies, the structure of
the molecular gas has been studied in terms of molecular clouds, but has been
overlooked beyond the cloud scale. We present an observational study of the
molecular gas at 49.5 degree <l<52.5 degree and -5.0 km/s <v_lsr <17.4 km/s.
The molecular gas is found in the form of a huge (>= 500 pc) filamentary gas
wisp. This has a large physical extent and a velocity dispersion of ~5 km/s.
The eastern part of the filamentary gas wisp is located ~130 pc above the
Galactic disk (which corresponds to 1.5-4 e-folding scale-heights), and the
total mass of the gas wisp is >= 1 X 10^5 M_sun. It is composed of two
molecular clouds and an expanding bubble. The velocity structure of the gas
wisp can be explained as a smooth quiescent component disturbed by the
expansion of a bubble. That the length of the gas wisp exceeds by much the
thickness of the molecular disk of the Milky Way is consistent with the
cloud-formation scenario in which the gas is cold prior to the formation of
molecular clouds. Star formation in the filamentary gas wisp occurs at the edge
of a bubble (G52L nebula), which is consistent with some models of triggered
star formation.


title: 10 Inventions on collapsible keyboards: A TRIZ based analysis

abstract:
  Although a bigger keyboard is often comfortable to work with, they cannot be
fit into laptop and small size computer boxes. The portable and handheld
computers need small size keyboards. So there is a need to reduce the size of
the keyboard to fit into the laptop box. There are various mechanisms to reduce
the size of the keyboard; collapsible keyboard is one of them.
  Although different inventions intend to achieve the same objective of
reducing the keyboard size, they all differ in their mechanism. For example,
some invention uses a compression mechanism, some invention uses a folding
mechanism, and some invention uses a collapsing mechanism and so on.
  This article illustrates 10 inventions on collapsible keyboards from US
patent database. Each case is analyzed from a TRIZ perspective.


title:
Evidence for Water in the Rocky Debris of a Disrupted Extrasolar Minor
  Planet

abstract:
  The existence of water in extrasolar planetary systems is of great interest
as it constrains the potential for habitable planets and life. Here, we report
the identification of a circumstellar disk that resulted from the destruction
of a water-rich and rocky, extrasolar minor planet. The parent body formed and
evolved around a star somewhat more massive than the Sun, and the debris now
closely orbits the white dwarf remnant of the star. The stellar atmosphere is
polluted with metals accreted from the disk, including oxygen in excess of that
expected for oxide minerals, indicating the parent body was originally composed
of 26% water by mass. This finding demonstrates that water-bearing
planetesimals exist around A- and F-type stars that end their lives as white
dwarfs.


title:
Supernova enrichment and dynamical histories of solar-type stars in
  clusters

abstract:
  We use N-body simulations of star cluster evolution to explore the hypothesis
that short-lived radioactive isotopes found in meteorites, such as 26-Al, were
delivered to the Sun's protoplanetary disc from a supernova at the epoch of
Solar System formation. We cover a range of star cluster formation parameter
space and model both clusters with primordial substructure, and those with
smooth profiles. We also adopt different initial virial ratios - from cool,
collapsing clusters to warm, expanding associations. In each cluster we place
the same stellar population; the clusters each have 2100 stars, and contain one
massive 25M_Sun star which is expected to explode as a supernova at about
6.6Myr. We determine the number of Solar (G)-type stars that are within 0.1 -
0.3pc of the 25M_Sun star at the time of the supernova, which is the distance
required to enrich the protoplanetary disc with the 26-Al abundances found in
meteorites. We then determine how many of these G-dwarfs are unperturbed
`singletons'; stars which are never in close binaries, nor suffer sub-100au
encounters, and which also do not suffer strong dynamical perturbations.
  The evolution of a suite of twenty initially identical clusters is highly
stochastic, with the supernova enriching over 10 G-dwarfs in some clusters, and
none at all in others. Typically only ~25 per cent of clusters contain
enriched, unperturbed singletons, and usually only 1 - 2 per cluster (from a
total of 96 G-dwarfs in each cluster). The initial conditions for star
formation do not strongly affect the results, although a higher fraction of
supervirial (expanding) clusters would contain enriched G-dwarfs if the
supernova occurred earlier than 6.6Myr. If we sum together simulations with
identical initial conditions, then ~1 per cent of all G-dwarfs in our
simulations are enriched, unperturbed singletons.


title: A Holographic Model of the Kondo Effect

abstract:
  We propose a model of the Kondo effect based on the Anti-de Sitter/Conformal
Field Theory (AdS/CFT) correspondence, also known as holography. The Kondo
effect is the screening of a magnetic impurity coupled anti-ferromagnetically
to a bath of conduction electrons at low temperatures. In a (1+1)-dimensional
CFT description, the Kondo effect is a renormalization group flow triggered by
a marginally relevant (0+1)-dimensional operator between two fixed points with
the same Kac-Moody current algebra. In the large-N limit, with spin SU(N) and
charge U(1) symmetries, the Kondo effect appears as a (0+1)-dimensional
second-order mean-field transition in which the U(1) charge symmetry is
spontaneously broken. Our holographic model, which combines the CFT and large-N
descriptions, is a Chern-Simons gauge field in (2+1)-dimensional AdS space,
AdS3, dual to the Kac-Moody current, coupled to a holographic superconductor
along an AdS2 subspace. Our model exhibits several characteristic features of
the Kondo effect, including a dynamically generated scale, a resistivity with
power-law behavior in temperature at low temperatures, and a spectral flow
producing a phase shift. Our holographic Kondo model may be useful for studying
many open problems involving impurities, including for example the Kondo
lattice problem.


title:
Eclipsing Binary Stars in the OGLE-III Fields of the Small Magellanic
  Cloud

abstract:
  We present a large sample of eclipsing binary stars detected in the Small
Magellanic Cloud fields covering about 14 square degrees that have been
monitored for eight years during the third phase of the OGLE survey. This is
the largest set of such variables containing 6138 objects, of which 777 are
contact and 5361 non-contact binaries. The estimated completeness of this
sample is around 82%. We analyze the statistical properties of the sample and
present selected interesting objects: 32 systems having eccentric orbit with
visible apsidal motion, one Transient Eclipsing Binary, ten RS CVn type stars,
22 still unexplained Double-Periodic Variable stars, and 15 candidates for
doubly eclipsing quadruple systems. Based on the OGLE-III proper motions, we
classified 47 binaries from our sample as foreground Galactic stars. We also
list candidates suitable for the SMC distance determination.


title:
Cosmic rays can drive strong outflows from gas-rich high-redshift disk
  galaxies

abstract:
  We present simulations of the magnetized interstellar medium (ISM) in models
of massive star forming (40 Msun / yr) disk galaxies with high gas surface
densities (~100 Msun / pc^2) similar to observed star forming high-redshift
disks. We assume that type II supernovae deposit 10 per cent of their energy
into the ISM as cosmic rays and neglect the additional deposition of thermal
energy or momentum. With a typical Galactic diffusion coefficient for CRs (3e28
cm^2 / s) we demonstrate that this process alone can trigger the local
formation of a strong low density galactic wind maintaining vertically open
field lines. Driven by the additional pressure gradient of the relativistic
fluid the wind speed can exceed 1000 km/s, much higher than the escape velocity
of the galaxy. The global mass loading, i.e. the ratio of the gas mass leaving
the galactic disk in a wind to the star formation rate becomes of order unity
once the system has settled into an equilibrium. We conclude that relativistic
particles accelerated in supernova remnants alone provide a natural and
efficient mechanism to trigger winds similar to observed mass-loaded galactic
winds in high-redshift galaxies. These winds also help explaining the low
efficiencies for the conversion of gas into stars in galaxies as well as the
early enrichment of the intergalactic medium with metals. This mechanism can be
at least of similar importance than the traditionally considered momentum
feedback from massive stars and thermal and kinetic feedback from supernova
explosions.


title:
A new scheme for matching general relativistic ideal
  magnetohydrodynamics to its force-free limit

abstract:
  We present a new computational method for smoothly matching general
relativistic ideal magnetohydrodynamics (MHD) to its force-free limit. The
method is based on a flux-conservative formalism for MHD and its force-free
limit, and a vector potential formulation for the induction equation to
maintain the zero divergence constraint for the magnetic field. The force-free
formulation we adopt evolves the magnetic field and the Poynting vector,
instead of the magnetic and electric fields. We show that our force-free code
passes a robust suite of tests, performed both in 1D flat spacetime and in 3D
black hole spacetimes. We also demonstrate that our matching technique
successfully reproduces the aligned rotator force-free solution. Our new
techniques are suitable for studying electromagnetic effects and predicting
electromagnetic signals arising in many different curved spacetime scenarios.
For example, we can treat spinning neutron stars, either in isolation or in
compact binaries, that have MHD interiors and force-free magnetospheres.


title:
Constraining stellar population models - I. Age, metallicity, and
  abundance pattern compilation for Galactic globular clusters

abstract:
  We present an extenstive literature compilation of age, metallicity, and
chemical abundance pattern information for the 41 Galactic globular clusters
(GGCs) studied by Schiavon et al. (2005). Our compilation constitutes a notable
improvement over previous similar work, particularly in terms of chemical
abundances. Its primary purpose is to enable detailed evaluations of and
refinements to stellar population synthesis models designed to recover the
above information for unresolved stellar systems based on their integrated
spectra. However, since the Schiavon sample spans a wide range of the known GGC
parameter space, our compilation may also benefit investigations related to a
variety of astrophysical endeavours, such as the early formation of the Milky
Way, the chemical evolution of GGCs, and stellar evolution and nucleosynthesis.
For instance, we confirm with our compiled data that the GGC system has a
bimodal metallicity distribution and is uniformly enhanced in the
alpha-elements. When paired with the ages of our clusters, we find evidence
that supports a scenario whereby the Milky Way obtained its globular clusters
through two channels, in situ formation and accretion of satellite galaxies.
The distributions of C, N, O, and Na abundances and the dispersions thereof per
cluster corroborate the known fact that all GGCs studied so far with respect to
multiple stellar populations have been found to harbour them. Finally, using
data on individual stars, we also confirm that the atmospheres of stars become
progressively polluted by CN(O)-processed material after they leave the main
sequence and uncover evidence which suggests the alpha-elements Mg and Ca may
originate from more than one nucleosynthetic production site. [abridged]


title:
Carbon-enhanced Metal-poor Stars in SDSS/SEGUE. I. Carbon Abundance
  Estimation and Frequency of CEMP Stars

abstract:
  We describe a method for the determination of stellar [C/Fe] abundance ratios
using low-resolution (R = 2000) stellar spectra from the SDSS and SEGUE. By
means of a star-by-star comparison with a set of SDSS/SEGUE spectra with
available estimates of [C/Fe] based on published high-resolution analyses, we
demonstrate that we can measure [C/Fe] from SDSS/SEGUE spectra with S/N > 15 to
a precision better than 0.35 dex. Using the measured carbon-to-iron abundance
ratios obtained by this technique, we derive the frequency of carbon-enhanced
stars ([C/Fe] > +0.7) as a function of [Fe/H], for both the SDSS/SEGUE stars
and other samples from the literature. We find that the differential frequency
slowly rises from almost zero to about 14% at [Fe/H] ~ -2.4, followed by a
sudden increase, by about a factor of three, to 39% from [Fe/H] ~ -2.4 to
[Fe/H] ~ -3.7. We also examine how the cumulative frequency of CEMP stars
varies across different luminosity classes. The giant sample exhibits a
cumulative CEMP frequency of 32% for [Fe/H] < -2.5, 31% for [Fe/H] < -3.0, and
33% for [Fe/H] < -3.5. For the main-sequence turnoff stars, we obtain a lower
cumulative CEMP frequency, around 10% for [Fe/H] < -2.5. The dwarf population
displays a large change in the cumulative frequency for CEMP stars below [Fe/H]
= -2.5, jumping from 15% for [Fe/H] < -2.5 to about 75% for [Fe/H] < -3.0. When
we impose a restriction with respect to distance from the Galactic mid-plane
(|Z| < 5 kpc), the frequency of the CEMP giants does not increase at low
metallicity ([Fe/H] < -2.5), but rather, decreases, due to the dilution of
C-rich material in stars that have undergone mixing with CNO-processed material
from their interiors. The frequency of CEMP stars near the main-sequence
turnoff, which are not expected to have experienced mixing, increases for
[Fe/H] < -3.0. [abridged]


title:
Carbon-enhanced Metal-poor Stars in SDSS/SEGUE. II. Comparison of CEMP
  Star Frequencies with Binary Population Synthesis Models

abstract:
  We present a comparison of the frequencies of carbon-enhanced metal-poor
(CEMP) giant and main-sequence turnoff stars, selected from the Sloan Digital
Sky Survey and the Sloan Extension for Galactic Understanding and Exploration,
with predictions from asymptotic giant-branch (AGB) mass-transfer models. We
consider two initial mass functions (IMFs)-a Salpeter IMF, and a mass function
with a characteristic mass of 10 solar mass. These comparisons indicate good
agreement between the observed CEMP frequencies for stars with [Fe/H] > -1.5
and a Salpeter IMF, but not with an IMF having a higher characteristic mass.
Thus, while the adopted AGB model works well for low-mass progenitor stars, it
does not do so for high-mass progenitors. Our results imply that the IMF
shifted from high- to low-mass dominated in the early history of the Milky Way,
which appears to have occurred at a "chemical time" between [Fe/H] = -2.5 and
[Fe/H] = -1.5. The corrected CEMP frequency for the turnoff stars with [Fe/H] <
-3.0 is much higher than the AGB model prediction from the high-mass IMF,
supporting the previous assertion that one or more additional mechanisms, not
associated with AGB stars, are required for the production of carbon-rich
material below [Fe/H] = -3.0. [abridged]


title: Constraints on Large-Scale Dark Acoustic Oscillations from Cosmology

abstract:
  If all or a fraction of the dark matter (DM) were coupled to a bath of dark
radiation (DR) in the early Universe we expect the combined DM-DR system to
give rise to acoustic oscillations of the dark matter until it decouples from
the DR. Much like the standard baryon acoustic oscillations, these dark
acoustic oscillations (DAO) imprint a characteristic scale, the sound horizon
of dark matter, on the matter power spectrum. We compute in detail how the
microphysics of the DM-DR interaction affects the clustering of matter in the
Universe and show that the DAO physics also gives rise to unique signatures in
the temperature and polarization spectra of the cosmic microwave background
(CMB). We use cosmological data from the CMB, baryon acoustic oscillations
(BAO), and large-scale structure to constrain the possible fraction of
interacting DM as well as the strength of its interaction with DR. Like nearly
all knowledge we have gleaned about dark matter since inferring its existence
this constraint rests on the betrayal by gravity of the location of otherwise
invisible dark matter. Although our results can be straightforwardly applied to
a broad class of models that couple dark matter particles to various light
relativistic species, in order to make quantitative predictions, we model the
interacting component as dark atoms coupled to a bath of dark photons. We find
that linear cosmological data and CMB lensing put strong constraints on
existence of DAO features in the CMB and the large-scale structure of the
Universe. Interestingly, we find that at most ~5% of all DM can be very
strongly interacting with DR. We show that our results are surprisingly
constraining for the recently proposed Double-disk DM model, a novel example of
how large-scale precision cosmological data can be used to constrain galactic
physics and sub-galactic structure.


title:
Spatially Modulated Instabilities for Scaling Solutions at Finite Charge
  Density

abstract:
  We consider finite charge density geometries which interpolate between AdS2 x
R2 in the infrared and AdS4 in the ultraviolet, while traversing an
intermediate regime of anisotropic Lifshitz scaling and hyperscaling violation.
We work with Einstein-Maxwell-dilaton models and only turn on a background
electric field. The spatially modulated instabilities of the near-horizon AdS2
part of the geometry are used to argue that the scaling solutions themselves
should be thought of as being unstable -- in the deep infrared -- to spatially
modulated phases. We identify instability windows for the scaling exponents,
which are refined further by requiring the solutions to satisfy the null energy
condition. This analysis reinforces the idea that, for large classes of models,
spatially modulated phases describe the ground state of hyperscaling violating
scaling geometries.


title:
Purely dry mergers do not explain the observed evolution of massive
  early-type galaxies since z = 1

abstract:
  Several studies have suggested that the observed size evolution of massive
early-type galaxies (ETGs) can be explained as a combination of dry mergers and
progenitor bias, at least since z\sim1. In this paper we carry out a new test
of the dry-merger scenario based on recent lensing measurements of the
evolution of the mass density profile of ETGs. We construct a theoretical model
for the joint evolution of the size and mass density profile slope \gamma'
driven by dry mergers occurring at rates given by cosmological simulations.
Such dry-merger model predicts a strong decrease of \gamma' with cosmic time,
inconsistent with the almost constant \gamma' inferred from observations in the
redshift range 0<z<1. We then show with a simple toy model that a modest amount
of cold gas in the mergers -- consistent with the upper limits on recent star
formation in ETGs -- is sufficient to reconcile the model with measurements of
\gamma'. By fitting for the amount of gas accreted during mergers, we find that
models with dissipation are consistent with observations of the evolution in
both size and density slope, if \sim4% of the total final stellar mass arises
from the gas accreted since z\sim1. Purely dry merger models are ruled out at >
99% CL. We thus suggest a scenario where the outer regions of massive ETGs grow
by accretion of stars and dark matter, while small amounts of dissipation and
nuclear star formation conspire to keep the mass density profile constant and
approximately isothermal.


title:
Thermal treatment of superconductor thin film of the BSCCO system using
  domestic microwave oven

abstract:
  In this work, we report the preparation of a superconductor thin film of the
BSCCO system using a good quality powder with nominal composition
Bi_{1.8}Pb_{0.4}Sr_2CaCu_2O_x which was thermally treated using a domestic
microwave oven (2.45 GHz, 800 W). This film was grew on a single crystal of
LaAlO_3(100) substrate and exhibited a crystalline structure with the c-axis
perpendicular to the plane of the substrate. An onset superconducting
transition temperature was measured at 80 K.


title: Three-manifold mutations detected by Heegaard Floer homology

abstract:
  Given a self-diffeomorphism h of a closed, orientable surface S and an
embedding f of S into a three-manifold M, we construct a mutant manifold N by
cutting M along f(S) and regluing by h. We will consider whether there are any
gluings such that for any embedding, the manifold and its mutant have
isomorphic Heegaard Floer homology. In particular, we will demonstrate that if
the gluing is not isotopic to the identity, then there exists an embedding of S
into a three-manifold M such that the rank of the non-torsion summands of the
Heegaard Floer homology of M differs from that of its mutant. We will also show
that if the gluing map is isotopic to neither the identity nor the genus-two
hyperelliptic involution, then there exists an embedding of S into a
three-manifold M such that the total rank of the Heegaard Floer homology of M
differs from that of its mutant.


title:
The Effects of Front-Surface Target Structures on Properties of
  Relativistic Laser-Plasma Electrons

abstract:
  We report the results of a study of the role of prescribed geometrical
structures on the front of a target in determining the energy and spatial
distribution of relativistic laser-plasma electrons. Our 3D PIC simulation
studies apply to short-pulse, high intensity laser pulses, and indicate that a
judicious choice of target front-surface geometry provides the realistic
possibility of greatly enhancing the yield of high energy electrons, while
simultaneously confining the emission to narrow (< 5 degree) angular cones.


title: Scattering polarization in solar flares

abstract:
  There is an ongoing debate about the origin and even the very existence of a
high degree of linear polarization of some chromospheric spectral lines
observed in solar flares. The standard explanation of these measurements is in
terms of the impact polarization caused by non-thermal proton and/or electron
beams. In this work, we study the possible role of resonance line polarization
due to radiation anisotropy in the inhomogeneous medium of the flare ribbons.
We consider a simple two-dimensional model of the flaring chromosphere and we
solve self-consistently the non-LTE problem taking into account the role of
resonant scattering polarization and of the Hanle effect. Our calculations show
that the horizontal plasma inhomogeneities at the boundary of the flare ribbons
can lead to a significant radiation anisotropy in the line formation region
and, consequently, to a fractional linear polarization of the emergent
radiation of the order of several percent. Neglecting the effects of impact
polarization, our model can provide a clue for resolving some of the common
observational findings, namely: (1) why a high degree of polarization appears
mainly at the edges of the flare ribbons; (2) why polarization can also be
observed during the gradual phase of a flare; (3) why polarization is mostly
radial or tangential. We conclude that the radiation transfer in the realistic
multi-dimensional models of solar flares needs to be considered as an essential
ingredient for understanding the observed spectral line polarization.


title: Quickest Change-Point Detection: A Bird's Eye View

abstract:
  We provide a bird's eye view onto the area of sequential change-point
detection. We focus on the discrete-time case with known pre- and post-change
data distributions and offer a summary of the forefront asymptotic results
established in each of the four major formulations of the underlying
optimization problem: Bayesian, generalized Bayesian, minimax, and
multi-cyclic.


title: Thermodynamics of Magnetised Kerr-Newman Black Holes

abstract:
  The thermodynamics of a magnetised Kerr-Newman black hole is studied to all
orders in the appended magnetic field $B$. The asymptotic properties of the
metric and other fields are dominated by the magnetic flux that extends to
infinity along the axis, leading to subtleties in the calculation of conserved
quantities such as the angular momentum and the mass. We present a detailed
discussion of the implementation of a Wald-type procedure to calculate the
angular momentum, showing how ambiguities that are absent in the usual
asymptotically-flat case may be resolved by the requirement of gauge
invariance. We also present a formalism from which we are able to obtain an
expression for the mass of the magnetised black holes. The expressions for the
mass and the angular momentum are shown to be compatible with the first law of
thermodynamics and a Smarr type relation. Allowing the appended magnetic field
$B$ to vary results in an extra term in the first law of the form $-\mu dB$
where $\mu$ is interpreted as an induced magnetic moment. Minimising the total
energy with respect to the total charge $Q$ at fixed values of the angular
momentum and energy of the seed metric allows an investigation of Wald's
process. The Meissner effect is shown to hold for electrically neutral extreme
black holes. We also present a derivation of the angular momentum for black
holes in the four-dimensional STU model, which is ${\cal N}=2$ supergravity
coupled to three vector multiplets.


title:
Rotational Dynamics and Angular Locking of Nanoparticles at liquid
  Interfaces

abstract:
  Nanoparticles with different surface morphologies that straddle the interface
between two immiscible liquids are studied via molecular dynamics simulations.
The methodology employed allows us to compute the interfacial free energy at
different angular orientations of the nanoparticle. Due to their atomistic
nature, the studied nanoparticles present both microscale and macroscale
geometrical features and cannot be accurately modeled as a perfectly smooth
body (e.g., spheres, cylinders). Under certain physical conditions, microscale
features can produce free energy barriers that are much larger than the thermal
energy of the surrounding media. The presence of these energy barriers can
effectively "lock" the particle at specific angular orientations with respect
to the liquid-liquid interface. This work provides new insights on the
rotational dynamics of Brownian particles at liquid interfaces and suggests
possible strategies to exploit the effects of microscale features with given
geometric characteristics.


title:
Testing Bell's Inequality with Cosmic Photons: Closing the
  Setting-Independence Loophole

abstract:
  We propose a practical scheme to use photons from causally disconnected
cosmic sources to set the detectors in an experimental test of Bell's
inequality. In current experiments, with settings determined by quantum random
number generators, only a small amount of correlation between detector settings
and local hidden variables, established less than a millisecond before each
experiment, would suffice to mimic the predictions of quantum mechanics. By
setting the detectors using pairs of quasars or patches of the cosmic microwave
background, observed violations of Bell's inequality would require any such
coordination to have existed for billions of years --- an improvement of 20
orders of magnitude.


title: Clustering of inertial cloud droplets in isotropic turbulence

abstract:
  This article accompanies the submission of a fluid dynamics video (entry
102248) of inertial cloud droplet clustering in isotropic turbulence for the
Gallery of Fluid Motion of the 66th Annual Meeting of the American Physical
Society, Division of Fluid Dynamics.


title:
Dropping the Ball: The effect of anisotropic granular materials on
  ejecta and impact crater shape

abstract:
  In this fluid dynamics video, we present an experimental investigation of the
shape of impact craters in granular materials. Complex crater shapes, including
polygons, have been observed in many terrestrial planets as well as moons and
asteroids. We release spherical projectiles from different heights above a
granular bed (sand). The experiments demonstrate two different techniques to
create non-circular impact craters, which we measure by digitizing the final
crater topography. In the first method, we create trenches in the sand to mimic
fault lines or valleys on a planetary target. During impact, ejecta move faster
in the direction of the trenches, creating nearly elliptical craters with the
major axis running parallel to the trench. Larger trenches lead to more oblong
craters. In the second method, a hose beneath the surface of the sand injects
nitrogen gas. The pressure of the gas counters the hydrostatic pressure of the
sand, greatly reducing static friction between grains above the injection
point, without disturbing the surface. The affected sand has lower resistance
to impact, creating a knob in the otherwise circular crater rim.


title: Identification of cromosomal translocation hotspots via scan statistics

abstract:
  The detection of genomic regions unusually rich in a given pattern is an
important undertaking in the analysis of next generation sequencing data.
Recent studies of chromosomal translocations in activated B lymphocytes have
identified regions that are frequently translocated to c-myc oncogene. A
quantitative method for the identification of translocation hotspots was
crucial to this study. Here we improve this analysis by using a simple
probabilistic model and the framework provided by scan statistics to define the
number and location of translocation breakpoint hotspots. A key feature of our
method is that it provides a global chromosome-wide significance level to
clustering, as opposed to previous methods based on local criteria. Whilst
being motivated by a specific application, the detection of unusual clusters is
a widespread problem in bioinformatics. We expect our method to be useful in
the analysis of data from other experimental approaches such as of ChIP-seq and
4C-seq.


title: Theory Summary

abstract:
  Talk given at the XLVIII Rencontres de Moriond, Electroweak Interactions and
Unified Theories, La Thuile, Italy, 2-9 March 2013, to appear in the
Proceedings.


title:
On the value set of small families of polynomials over a finite field,
  II

abstract:
  We obtain an estimate on the average cardinality of the value set of any
family of monic polynomials of Fq[T] of degree d for which s consecutive
coefficients a_{d-1},...,a_{d-s} are fixed. Our estimate asserts that
\mathcal{V}(d,s,\bfs{a})=\mu_d\,q+\mathcal{O}(q^{1/2}), where
\mathcal{V}(d,s,\bfs{a}) is such an average cardinality,
\mu_d:=\sum_{r=1}^d{(-1)^{r-1}}/{r!} and \bfs{a}:=(a_{d-1},...,a_{d-s}). We
also prove that \mathcal{V}_2(d,s,\bfs{a})=\mu_d^2\,q^2+\mathcal{O}(q^{3/2}),
where that \mathcal{V}_2(d,s,\bfs{a}) is the average second moment on any
family of monic polynomials of Fq[T] of degree d with s consecutive
coefficients fixed as above. Finally, we show that
\mathcal{V}_2(d,0)=\mu_d^2\,q^2+\mathcal{O}(q), where \mathcal{V}_2(d,0)
denotes the average second moment of all monic polynomials in Fq[T] of degree d
with f(0)=0. All our estimates hold for fields of characteristic p>2 and
provide explicit upper bounds for the constants underlying the
\mathcal{O}--notation in terms of d and s with "good" behavior. Our approach
reduces the questions to estimate the number of Fq--rational points with
pairwise--distinct coordinates of a certain family of complete intersections
defined over Fq. A critical point for our results is an analysis of the
singular locus of the varieties under consideration, which allows to obtain
rather precise estimates on the corresponding number of Fq--rational points.


title:
Wake Turbulence of Two NREL 5-MW Wind Turbines Immersed in a Neutral
  Atmospheric Boundary-Layer Flow

abstract:
  The fluid dynamics video considers an array of two NREL 5-MW turbines
separated by seven rotor diameters in a neutral atmospheric boundary layer
(ABL). The neutral atmospheric boundary-layer flow data were obtained from a
precursor ABL simulation using a Large-Eddy Simulation (LES) framework within
OpenFOAM. The mean wind speed at hub height is 8m/s, and the surface roughness
is 0.2m. The actuator line method (ALM) is used to model the wind turbine
blades by means of body forces added to the momentum equation. The fluid
dynamics video shows the root and tip vortices emanating from the blades from
various viewpoints. The vortices become unstable and break down into
large-scale turbulent structures. As the wakes of the wind turbines advect
further downstream, smaller-scale turbulence is generated. It is apparent that
vortices generated by the blades of the downstream wind turbine break down
faster due to increased turbulence levels generated by the wake of the upstream
wind turbine.


title: Bethe-Salpeter Equations from the 4PI effective action

abstract:
  In this paper we derive a hierarchy of integral equations from the 4PI
effective action which have the form of Bethe-Salpeter equations. We show that,
together with the equation of motion for the self-consistent 4-vertex, these
integral equations are closed, and that their expansions give infinite series
of connected diagrams which have the correct symmetry.


title:
Phase boundaries of a spin-3/2 Blume-Emery-Griffiths model on a
  honeycomb lattice

abstract:
  The spin-3/2 Blume-Emery-Griffiths model on a honeycomb lattice is studied by
Monte Carlo simulations with the goal to determine phase diagrams for a range
of the model parameters and to investigate the nature of the phase transitions
between the respective phases. For positive values of the biquadratic to
bilinear interaction ratio $\alpha$, we find two ferromagnetically ordered
phases, F1 and F2, with the sublattice magnetizations (1/2,1/2) and (3/2,3/2),
respectively, and our results confirm the discontinuous character of the
order-disorder critical line as a function of the single-ion anisotropy
strength, predicted by the effective-field theory (EFT). For negative values of
$\alpha$, there is another ferrimagnetic (FRM) phase of the type (1/2,3/2),
located between F1 and F2. However, the step-like variation of the
order-disorder critical frontier obtained from EFT for large negative $\alpha$
is not reproduced and thus deemed artifact of the EFT approximation.
Finite-size scaling analysis performed at various points between the respective
identified phases gave the ratio of critical exponents $\gamma/\nu$ consistent
with the 2D Ising universality class, except in the vicinity of the boundary
intersection, where the results deviated from the standard values beyond the
measurement errors.


title: Bertini for Macaulay2

abstract:
  Numerical algebraic geometry is the field of computational mathematics
concerning the numerical solution of polynomial systems of equations. Bertini,
a popular software package for computational applications of this field,
includes implementations of a variety of algorithms based on polynomial
homotopy continuation. The Macaulay2 package Bertini.m2 provides an interface
to Bertini, making it possible to access the core run modes of Bertini in
Macaulay2. With these run modes, users can find approximate solutions to
zero-dimensional systems and positive-dimensional systems, test numerically
whether a point lies on a variety, sample numerically from a variety, and
perform parameter homotopy runs.


title: Entropy of spin clusters with frustrated geometry

abstract:
  Geometrically frustrated clusters of Ising spins of different shapes on a
triangular lattice are studied by exact enumeration and Monte Carlo simulation.
The focus is laid on the ground-state energy and residual entropy behaviors as
functions of the cluster shape and size, as well as the spin value. Depending
on the cluster shape, the residual entropy density on approach to the
thermodynamic limit can either vanish or remain finite and the dependence can
be decreasing, increasing or non-monotonic. Nevertheless, the relative
entropies normalized by the respective thermodynamic limit values turn out to
be little sensitive to the spin value. Some interesting finite-temperature
properties of the clusters are also discussed and attention is drawn to their
magnetocaloric properties.


title:
Electrokinetically Driven Reversible Banding of Colloidal Particles Near
  the Wall

abstract:
  This fluid dynamics video, presented at the 66th Annual Meeting of the
American Physical Society Division of Fluid Dynamics (Pittsburgh, PA), shows
how dielectric colloidal polystyrene (PS) particles with a negative surface
charge in a dilute suspension flowing through a microchannel can be manipulated
and assembled into streamwise structures by using a combination of shear and an
applied negative electric field along the streamwise direction. Interestingly,
these structures are only observed within about 1 um of the wall, which also
has a negative surface charge, and are not present in the bulk flow.


title:
Hadron production in e+e- annihilation at BaBar, and implication for the
  muon anomalous magnetic moment

abstract:
  The BaBar collaboration has an extensive program of studying hadronic cross
sections in low-energy e+e- collisions, accessible via initial-state radiation.
Our measurements allow significant improvements in the precision of the
predicted value of the muon anomalous magnetic moment. These improvements are
necessary for illuminating the current ~3.6 sigma difference between the
predicted and the experimental values. We have published results on a number of
processes with two to six hadrons in the final state. We report here the
results of recent studies with final states that constitute the main
contribution to the hadronic cross section in the energy region between 1 and 3
GeV, as e+e- to K+K-, pi+pi-, and e+e- to 4 hadrons.


title: Modeling and simulation of a low grade urinary bladder carcinoma

abstract:
  In this work, we present a mathematical model of the initiation and
progression of a low-grade urinary bladder carcinoma. We simulate the crucial
processes involved in tumor growth, such as oxygen diffusion, carcinogen
penetration, and angiogenesis, within the framework of the urothelial cell
dynamics. The cell dynamics are modeled using the discrete technique of
Cellular Automata, while the continuous processes of carcinogen penetration and
oxygen diffusion are described by nonlinear diffusion-absorption equations. As
the availability of oxygen is necessary for tumor progression, processes of
oxygen transport to the tumor growth site seem most important. Our model yields
a theoretical insight into the main stages of development and growth of urinary
bladder carcinoma with emphasis on two most common types: bladder polyps and
carcinoma {\it in situ}. Analysis of histological structure of bladder tumor is
important to avoid misdiagnosis and wrong treatment and we expect our model to
be a valuable tool in the prediction of tumor grade and progression patterns,
based on the exposure to carcinogens and an oxygen dependent expression of
genes promoting tumor growth. Our numerical simulations have good qualitative
agreement with {\it in vivo} results reported in the corresponding medical
literature.


title:
Equivalence classes of subquotients of supersymmetric pseudodifferential
  operator modules

abstract:
  We study the equivalence classes of the non-resonant subquotients of spaces
of pseudodifferential operators between tensor density modules over the 1|1
superline, as modules of the Lie superalgebra of contact vector fields. There
is a 2-parameter family of subquotients with any given Jordan-Holder
composition series. We give a complete set of even equivalence invariants for
subquotients of all lengths. In the critical case of length 6, the even
equivalence classes within each non-resonant 2-parameter family are specified
by a pencil of conics. In lengths exceeding 6 our invariants are not fully
simplified: in length 7 we expect that there are only finitely many
equivalences other than conjugation, and in lengths exceeding 7 we expect that
conjugation is the only equivalence. We prove this in lengths exceeding 14. We
also analyze certain lacunary subquotients.


title: On Cline's Formula for some certain elements in a ring

abstract:
  In \cite{C, LCC}, it is proven that if an element $ab$ in a ring is
(generalized) Drazin invertible, then so is $ba$. In this paper, we give a new
and short proof of it in an effective manner. In particular, we show that if
$ab$ is strongly clean, then so is $ba$. Consequently, we see that if $1-ab$ is
strongly clean, then so is $1-ba$. Also, some characterizations are obtained
for some certain elements in a corner ring. It is shown that for an idempotent
$e$ and any arbitrary element $a$ in a ring, $ea+1-e$ is Drazin invertible if
and only if $eae$ is Drazin invertible.


title: Quantizations from (P)OVM's

abstract:
  We explain the powerful role that operator-valued measures can play in
quantizing any set equipped with a measure, for instance a group (resp. group
coset) with its invariant (resp. quasi-invariant) measure. Coherent state
quantization is a particular case. Such integral quantizations are illustrated
with two examples based on the Weyl-Heisenberg group and on the affine group
respectively. An interesting application of the affine quantization in quantum
cosmology is mentioned, and we sketch a construction of new coherent states for
the hydrogen atom.


title: Impinging Jet Resonant Modes at Mach 1.5

abstract:
  High speed impinging jets have been the focus of several studies owing to
their practical application and resonance dominated flow-field. The current
study focuses on the identification and visualization of the resonant modes at
certain critical impingement heights for a Mach 1.5 normally impinging jet.
These modes are associated with high amplitude, discrete peaks in the power
spectra and can be identified as having either axisymmetric or azimuthal modes.
Their visualization is accomplished through phase-locked Schlieren imaging and
fast-response pressure sensitive paint (PC-PSP) applied to the ground plane.


title:
Stability of character sums for positive-depth, supercuspidal
  representations

abstract:
  We re-write the character formul{\ae} of Adler and the second-named author in
a form amenable to explicit computations in $p$-adic harmonic analysis, and use
them to prove the stability of character sums for a modification of Reeder's
conjectural positive-depth, unramified, toral supercuspidal L-packets.


title: Measuring Software Diversity, with Applications to Security

abstract:
  In this work, we briefly introduce and discuss some of the diversity measures
used in Ecology. After a succinct description and analysis of the most relevant
ones, we single out the Shannon-Weiner index. We justify why it is the most
informative and relevant one for measuring software diversity. Then, we show
how it can be used for effectively assessing the diversity of various real
software ecosystems. We discover in the process a frequently overlooked
software monopoly, and its key security implications. We finally extract some
conclusions from the results obtained, focusing mostly on their security
implications.


title: A Preliminary Field Study of Game Programming on Mobile Devices

abstract:
  TouchDevelop is a new programming environment that allows users to create
applications on mobile devices. Applications created with TouchDevelop have
continued to grow in popularity since TouchDevelop was first released to public
in 2011. This paper presents a field study of 31,699 applications, focusing on
different characteristics between 539 game scripts and all other non-game
applications, as well as what make some game applications more popular than
others to users. The study provides a list of findings on characteristics of
game scripts and also implications for improving end-user programming of game
applications.


title: Dynamic Resource Management using Operating System-Level Virtualization

abstract:
  This thesis expands upon an existing system called Golondrina that performs
autonomic workload management among a cluster of hardware nodes running
operating system-level virtualization. Golondrina works by identifying
localized resource stress situations and attempting to dissipate them by
reallocating system resources and, if necessary, migrating or replicating
virtual machines. It is predicted that, using Golondrina, efficiency of similar
systems can be further improved by achieving greater resource utilization on
the hardware nodes while maintaining resource availability for each virtual
machine.
  The following topics are discussed: virtualization technologies and
associated challenges relating to resource management, the architecture and
design of Golondrina, intelligent resource reallocation based on predefined
policies, and preliminary results demonstrating the effects of a memory
resource management policy on the performance of a web application hosted in a
virtual environment.
  This research makes a significant contribution to the study of virtualized
data centres since currently no other system considers virtual machine
replication and dynamic memory reallocation as an approach to workload
management.


title: Compressible Flows in Fluidic Oscillators

abstract:
  We present qualitative observations on the internal flow characteristics of
fluidic oscillator geometries commonly referred to as sweeping jets in active
flow control applications. This is part of the fluid dynamics videos.


title:
Investigation of Rule 73 as Case Study of Class 4 Long-Distance Cellular
  Automata

abstract:
  Cellular automata (CA) have been utilized for decades as discrete models of
many physical, mathematical, chemical, biological, and computing systems. The
most widely known form of CA, the elementary cellular automaton (ECA), has been
studied in particular due to its simple form and versatility. However, these
dynamic computation systems possess evolutionary rules dependent on a
neighborhood of adjacent cells, which limits their sampling radius and the
environments that they can be used in.
  The purpose of this study was to explore the complex nature of
one-dimensional CA in configurations other than that of the standard ECA.
Namely, "long-distance cellular automata" (LDCA), a construct that had been
described in the past, but never studied. I experimented with a class of LDCA
that used spaced sample cells unlike ECA, and were described by the notation
LDCA-x-y-n, where x and y represented the amount of spacing between the cell
and its left and right neighbors, and n denoted the length of the initial tape
for tapes of finite size. Some basic characteristics of ECA are explored in
this paper, such as seemingly universal behavior, the prevalence of complexity
with varying neighborhoods, and qualitative behavior as a function of x and y
spacing.
  Focusing mainly on purely Class 4 behavior in LDCA-1-2, I found that Rule 73
could potentially be Turing universal through the emulation of a cyclic tag
system, and revealed a connection between the mathematics of binary trees and
Eulerian numbers that might provide insight into unsolved problems in both
fields.


title:
Multicriteria Evaluation and Sensitivity Analysis on Information
  Security

abstract:
  Information security plays a significant role in recent information society.
Increasing number and impact of cyber attacks on information assets have
resulted the increasing awareness among managers that attack on information is
actually attack on organization itself. Unfortunately, particular model for
information security evaluation for management levels is still not well
defined. In this study, decision analysis based on Ternary Analytic Hierarchy
Process (T-AHP) is proposed as a novel model to aid managers who responsible in
making strategic evaluation related to information security issues. In
addition, sensitivity analysis is applied to extend our analysis by using
several "what-if" scenarios in order to measure the consistency of the final
evaluation. Finally, we conclude that the final evaluation made by managers has
a significant consistency shown by sensitivity analysis results.


title: Hydrodynamics in the wake of a pitching foil

abstract:
  The effect of flexibility on the hydrodynamic loads and on the flow
structures generated on a rectangular foil when oscillating in pitch has been
studied. Hydrodynamic loads were measured with a 6-axes balance, and the flow
structures were investigated by using a Digital Particle Image Velocimetry
(DPIV). It is known from nature's fin based propulsion mechanisms, that
appendage stiffness plays an important role in their propulsive efficiency. We
have studied four different stiffnesses, ranging from completely rigid to
highly flexible. Optimal efficiency has been observed for an intermediate case.
In this case, a moderately stronger trailing-edge vortex system takes place. A
very high level of flexibility of the foil results in a reduction of
efficiency.


title: Skew Strikes Back: New Developments in the Theory of Join Algorithms

abstract:
  Evaluating the relational join is one of the central algorithmic and most
well-studied problems in database systems. A staggering number of variants have
been considered including Block-Nested loop join, Hash-Join, Grace, Sort-merge
for discussions of more modern issues). Commercial database engines use finely
tuned join heuristics that take into account a wide variety of factors
including the selectivity of various predicates, memory, IO, etc. In spite of
this study of join queries, the textbook description of join processing is
suboptimal. This survey describes recent results on join algorithms that have
provable worst-case optimality runtime guarantees. We survey recent work and
provide a simpler and unified description of these algorithms that we hope is
useful for theory-minded readers, algorithm designers, and systems
implementors.


title: Phenomenological Aspects of TeV Scale Alternative Left-Right Model

abstract:
  We revisit the alternative left-right symmetric model, motivated by
superstring-inspired $E_6$ model. We systematically analyze the constraints
imposed by theoretical and experimental bounds on the parameter space of this
class of models. We perform a comprehensive analysis of the Higgs sector and
show that three neutral CP-even and two CP-odd Higgs bosons in addition to two
charged Higgs bosons can be light, of ${\cal O}(100)$ GeV.
  We emphasise that our model has a potential to account for the recent Large
Hadron Collider results for signal strength of Higgs decays. We also explore
discovery signatures of the exotic down-type quark, which is one of the salient
predictions of this model.


title: Tree split probabilities determine the branch lengths

abstract:
  The evolution of aligned DNA sequence sites is generally modeled by a Markov
process operating along the edges of a phylogenetic tree. It is well known that
the probability distribution on the site patterns at the tips of the tree
determines the tree and its branch lengths. However, the number of patterns is
typically much larger than the number of edges, suggesting considerable
redundancy in the branch length estimation. In this paper we ask whether the
probabilities of just the `edge-specific' patterns (the ones that correspond to
a change of state on a single edge) suffice to recover the branch lengths of
the tree, under a symmetric 2-state Markov process. We first show that this
holds provided the branch lengths are sufficiently short, by applying the
inverse function theorem. We then consider whether this restriction to short
branch lengths is necessary, and show that for trees with up to four leaves it
can be lifted. This leaves open the interesting question of whether this holds
in general.


title:
Predictions for the relation between strong HI absorbers and galaxies at
  redshift 3

abstract:
  We combine cosmological, hydrodynamical simulations with accurate radiative
transfer corrections to investigate the relation between strong HI absorbers
(N_HI >~ 10^17 /cm^2) and galaxies at redshift z = 3. We find a strong
anti-correlation between the column density and the impact parameter that
connects the absorber to the nearest galaxy. The median impact parameters for
Lyman Limit (LL) and Damped Lyman-{\alpha} (DLA) systems are ~10 and ~1 proper
kpc, respectively. If normalized to the size of the halo of the nearest central
galaxy, the median impact parameters for LL and DLA systems become ~1 and
~10^-1 virial radii, respectively. At a given HI column density, the impact
parameter increases with the mass of the closest galaxy, in agreement with
observations. We predict most strong HI absorbers to be most closely associated
with extremely low-mass galaxies, M_star < 10^8 M_sun and star formation rate
<10^-1 M_sun/yr. We also find a correlation between the column density of
absorbers and the mass of the nearest galaxy. This correlation is most
pronounced for DLAs with N_HI > 10^21 /cm^2 which are typically close to
galaxies with M_star >~ 10^9 M_sun. Similar correlations exist between column
density and other properties of the associated galaxies such as their star
formation rates, halo masses and HI content. The galaxies nearest to HI
absorbers are typically far too faint to be detectable with current
instrumentation, which is consistent with the high rate of (often unpublished)
non-detections in observational searches for the galaxy counterparts of strong
HI absorbers. Moreover, we predict that the detected nearby galaxies are
typically not the galaxies that are most closely associated with the absorbers,
thus causing the impact parameters, star formation rates and stellar masses of
the observed counterparts to be biased high.


title:
Double-double electromagnetically induced transparency with
  amplification

abstract:
  We show that an alkali atom with a tripod electronic structure can yield rich
electromagnetically induced transparency phenomena even at room temperature. In
particular we introduce double-double electromagnetically induced transparency
wherein signal and probe fields each have two transparency windows. Their group
velocities can be matched in either the first or second pair of transparency
windows. Moreover signal and probe fields can each experience coherent gain in
the second transparency windows. We explain using a
semi-classical-dressed-picture to connect the tripod electronic structure to a
double-\Lambda\ scheme.


title: Scalar Field as a Bose-Einstein Condensate?

abstract:
  We discuss the analogy between a classical scalar field with a
self-interacting potential, in a curved spacetime described by a quasi--bounded
state, and a trapped Bose-Einstein condensate. In this context, we compare the
Klein-Gordon equation with the Gross-Pitaevskii equation. Moreover, the
introduction of a curved background spacetime endows, in a natural way, an
equivalence to the Gross-Pitaevskii equation with an explicit confinement
potential. The curvature also induces a position dependent self-interaction
parameter. We exploit this analogy by means of the Thomas-Fermi approximation,
commonly used to describe the Bose-Einstein condensate, in order to analyze the
quasi bound scalar field distribution surrounding a black hole.


title:
Compact binary systems in scalar-tensor gravity. II. Tensor
  gravitational waves to second post-Newtonian order

abstract:
  We derive the tensor gravitational waveform generated by a binary of
nonspinning compact objects (black holes or neutron stars) in a general class
of scalar-tensor theories of gravity. The waveform is accurate to second
post-Newtonian order beyond the leading order quadrupole approximation. We use
the direct integration of the relaxed Einstein equations formalism,
appropriately adapted to scalar-tensor theories, along with previous results
for the equations of motion in these theories. The self-gravity of the compact
objects is treated with an approach developed by Eardley. The scalar field
causes deviations from the general relativistic waveform that depend only on a
small number of parameters. Among the effects of the scalar field are new
hereditary terms which depend on the past history of the source. One of these,
a dipole-dipole coupling, produces a zero-frequency "gravitational-wave memory"
equivalent to the Christodoulou memory of general relativity. In the special
case of two black holes, the waveform reduces to the general relativistic
waveform. For a mixed (black hole-neutron star) system, the waveform is
identical to that of Einstein's theory to first post-Newtonian order, with
deviations at higher order depending only on a single parameter. The behavior
in these cases matches that found for the equations of motion.


title: The Life of a Vortex Knot

abstract:
  The idea that the knottedness (hydrodynamic Helicity) of a fluid flow is
conserved has a long history in fluid mechanics. The quintessential example of
a knotted flow is a knotted vortex filament, however, owing to experimental
difficulties, it has not been possible until recently to directly generate
knotted vortices in real fluids. Using 3D printed hydrofoils and high-speed
laser scanning tomography, we generate vortex knots and links and measure their
subsequent evolution. In both cases, we find that the vortices deform and
stretch until a series of vortex reconnections occurs, eventually resulting
several disjoint vortex rings.
  This article accompanies a fluid dynamics video entered into the Gallery of
Fluid Motion at the 66th Annual Meeting of the APS Division of Fluid Dynamics.


title: GPU-Framework for Teamwork Action Recognition

abstract:
  Real time processing for teamwork action recognition is a challenge, due to
complex computational models to achieve high system performance. Hence, this
paper proposes a framework based on Graphical Processing Units (GPUs) to
achieve a significant speed up in the performance of role based activity
recognition of teamwork. The framework can be applied in various fields,
especially athletic and military applications. Furthermore, the framework can
be customized for many action recognition applications. The paper presents the
stages of the framework where GPUs are the main tool for performance
improvement. The speedup is achieved by performing video processing and Machine
learning algorithms on GPU. Video processing and machine learning algorithms
covers all computations involved in our framework. Video processing tasks on
involves GPU implementation of Motion detection, segmentation and object
tracking algorithms. In addition, our framework is integrated with GPUCV, a GPU
version of OpenCV functions. Machine learning tasks are supported under our
framework with GPU implementations of Support Vector Machine (SVM) for object
classification and feature discretization, Hidden Marcov Model (HMM) for
activity recognition phase, and ID3 algorithm for role recognition of team
members. The system was tested against UC-Teamwork dataset and speedup of 20X
has been achieved on NVidia 9500GT graphics card (32 500MHZ processors).


title:
It's Alive! Spontaneous Motion of Shear Thickening Fluids Floating on
  the Air-Water Interface

abstract:
  In this fluid dynamics video, we show the spontaneous random motion of thin
filaments of a shear-thickening colloidal dispersions floating on the surface
of water. The fluid is a dispersion of fumed silica nanoparticles in a low
molecular weight polypropylene glycol (PPG) solvent. No external field or force
is applied. The observed motion is driven by strong surface tension gradients
as the polypropylene glycol slowly diffuses from from the filaments into water,
resulting in the observed Marangoni flow. The motion is exaggerated by the thin
filament constructs by the attractive interactions between silica nanoparticles
and the PPG.


title:
Anti-glitch induced by collision of a solid body with the magnetar 1E
  2259+586

abstract:
  Glitches have been frequently observed in neutron stars. Previously these
glitches unexceptionally manifest as sudden spin-ups that can be explained as
due to impulsive transfer of angular momentum from the interior superfluid
component to the outer solid crust. Alternatively, such spin-up glitches may
also be due to large-scale crust-cracking events. However, an unprecedented
anti-glitch was recently reported for the magnetar 1E 2259+586. In this case,
the magnetar clearly exhibited a sudden spin-down, strongly challenging
previous glitch theories. Here we show that the anti-glitch can be well
explained by the collision of a small solid body with the magnetar. The
intruder has a mass of about $1.1 \times 10^{21}$ g. Its orbital angular
momentum is assumed to be antiparallel to that of the spinning magnetar, so
that the sudden spin-down can be naturally accounted for. The observed hard
X-ray burst and decaying softer X-ray emission associated with the anti-glitch
can also be reasonably explained. Our study indicates that a completely
different type of glitches as due to collisions between small bodies and
neutron stars should exist and may have already been observed previously. It
also hints a new way for studying the capture events by neutron stars: through
accurate timing observations of pulsars.


title: Flying with Abrupt Wing Flapping: Damselfly in Darting Flight

abstract:
  Damselflies show abrupt, darting flight, which is the envy of aero-engineers.
This amazing ability is used both to capture prey and, by males, to establish
territories that can attract females. In this work, high-resolution, high-speed
videos of a damselfly (Hetaerina Americana) in darting flight were obtained
using a photogrammetry system. Using a 3D subdivision surface reconstruction
methodology, the damselfly's wing deformation and kinematics were modeled and
reconstructed from those videos. High fidelity simulations were then carried
out in order to understand vortex formation in both near-field and far-field of
damselfly wings and examine the associated aerodynamic performance. A Cartesian
grid based sharp interface immersed boundary solver was used to handle such
flows in all their complexity.


title: A spinor description of flat surfaces in R^4

abstract:
  We describe the flat surfaces with flat normal bundle and regular Gauss map
immersed in R^4 using spinors and Lorentz numbers. We obtain a new proof of the
local structure of these surfaces. We also study the flat tori in the sphere
S^3 and obtain a new representation formula. We then deduce new proofs of their
global structure, and of the global structure of their Gauss map image.


title: Electro-Osmotic Instability and Chaos near Ion-Selective Surfaces

abstract:
  We present a "fluid dynamics video" showing results from direct numerical
simulations of electrokinetic transport in a binary electrolyte in two systems:
(1) next to an ion-selective membrane and (2) around a metallic cylinder. The
governing equations are the Poisson--Nernst--Planck and Navier--Stokes and our
DNS resolves the time and length scales associated with the thin electric
double layers. Our results show transition to chaotic dynamics when the applied
voltage across the characteristic length scale is above a threshold of
approximately 0.5 Volt. More details, in particular regarding system (1), are
given in our paper [Druzgalski et al. POF 25, 110804 (2013)].


title: Turbulence-Flame Interaction

abstract:
  A fluid dynamics video was created using data from a Direct Numerical
Simulation of a premixed n-heptane flame at high Karlovitz number. The
magnitude of vorticity and progress variable(a monotonically increasing
variable through the flame) illustrate the turbulence-flame interaction.


title: Subwavelength plasmonic chain for magneto-optics enhancement

abstract:
  We study the enhancement of the magneto-optical effect in subdiffraction
plasmonic chains. We show that in a periodic chain of the plasmonic
nanoparticles embedded in a magneto-optical medium, propagation of a guided
mode is accompanied by rotation of electrical dipoles (the Faraday effect). The
angle of rotation per 1 {\mu}m is two orders of magnitude greater than that in
the same bulk magneto-optical medium. We also demonstrate that the effect of
Ohmic losses can be significantly reduced by using a gain-assisted chain
composed of active core-shell nanoparticles (spasers). The dipole mode in such
an array of magneto-optical spasers exhibits high values of the Faraday
rotation and propagation length.


title:
Ion-neutral friction and accretion-driven turbulence in self-gravitating
  filaments

abstract:
  Recent Herschel observations have confirmed that filaments are ubiquitous in
molecular clouds and suggest that irrespectively of the column density, there
is a characteristic width of about 0.1 pc whose physical origin remains
unclear. We develop an analytical model that can be applied to self-gravitating
accreting filaments. It is based on one hand on the virial equilibrium of the
central part of the filament and on the other hand on energy balance between
the turbulence driven by accretion onto the filament and dissipation. We
consider two dissipation mechanisms the turbulent cascade and the ion-neutral
friction. Our model predicts that the width of the filament inner part is
almost independent of the column density and leads to values comparable to what
is inferred observationally if dissipation is due to ion-neutral friction. On
the contrary turbulent dissipation leads to a structure that is bigger and
depends significantly on the column density. Our model provides a reasonable
physical explanation which could explain the observed filament width when they
are self-gravitating. It predicts the correct order or magnitude though
hampered by some uncertainties.


title: No-Scale Ripple Inflation Revisited

abstract:
  We revisit the no-scale ripple inflation model, where no-scale supergravity
is modified by an additional term for the inflaton field in the Kahler
potential. This term not only breaks one SU(N,1) symmetry explicitly, but also
plays an important role for inflation. We generalize the superpotential in the
no-scale ripple inflation model slightly. There exists a discrete Z_2
symmetry/parity in the scalar potential in general, which can be preserved or
violated by the non-canonical nomalized inflaton kinetic term. Thus, there are
three inflation paths: one parity invariant path, and the left and right paths
for parity violating scenario. We show that the inflations along the parity
invariant path and right path are consistent with the Planck results. However,
the gavitino mass for the parity invariant path is so large that the inflation
results will be invalid if we consider the inflaton supersymmetry breaking soft
mass term. Thus, only the inflation along the right path gives the correct and
consistent results. Notably, the tensor-to-scalar ratio in such case can be
large, with a value around 0.05, which may be probed by the future Planck
experiment.


title: Enumeration of Hybrid Domino-Lozenge Tilings II: Quasi-octagonal regions

abstract:
  We use the subgraph replacement method to prove a simple product formula for
the tilings of an 8-vertex counterpart of Propp's quasi-hexagons (Problem 16 in
New Perspectives in Geometric Combinatorics, Cambridge University Press, 1999),
called quasi-octagon.


title: Visualizing Bags of Vectors

abstract:
  The motivation of this work is two-fold - a) to compare between two different
modes of visualizing data that exists in a bag of vectors format b) to propose
a theoretical model that supports a new mode of visualizing data. Visualizing
high dimensional data can be achieved using Minimum Volume Embedding, but the
data has to exist in a format suitable for computing similarities while
preserving local distances. This paper compares the visualization between two
methods of representing data and also proposes a new method providing sample
visualizations for that method.


title: Scrambled and Unscrambled Turbulence

abstract:
  The linked fluid dynamics videos depict Rayleigh-Taylor turbulence when
driven by a complex acceleration profile involving two stages of acceleration
interspersed with a stage of stabilizing deceleration. Rayleigh-Taylor (RT)
instability occurs at the interface separating two fluids of different
densities, when the lighter fluid is accelerated in to the heavier fluid. The
turbulent mixing arising from the development of the miscible RT instability is
of key importance in the design of Inertial Confinement Fusion capsules, and to
the understanding of astrophysical events, such as Type Ia supernovae. By
driving this flow with an accel-decel-accel profile, we have investigated how
structures in RT turbulence are affected by a sudden change in the direction of
the acceleration first from destabilizing acceleration to deceleration, and
followed by a restoration of the unstable acceleration. By studying turbulence
under such highly non-equilibrium conditions, we hope to develop an
understanding of the response and recovery of self-similar turbulence to sudden
changes in the driving acceleration.