title:
Considering the Case for Biodiversity Cycles: Reexamining the Evidence
  for Periodicity in the Fossil Record

abstract:
  Medvedev and Melott (2007) have suggested that periodicity in fossil
biodiversity may be induced by cosmic rays which vary as the Solar System
oscillates normal to the galactic disk. We re-examine the evidence for a 62
million year (Myr) periodicity in biodiversity throughout the Phanerozoic
history of animal life reported by Rohde & Mueller (2005), as well as related
questions of periodicity in origination and extinction. We find that the signal
is robust against variations in methods of analysis, and is based on
fluctuations in the Paleozoic and a substantial part of the Mesozoic.
Examination of origination and extinction is somewhat ambiguous, with results
depending upon procedure. Origination and extinction intensity as defined by RM
may be affected by an artifact at 27 Myr in the duration of stratigraphic
intervals. Nevertheless, when a procedure free of this artifact is implemented,
the 27 Myr periodicity appears in origination, suggesting that the artifact may
ultimately be based on a signal in the data. A 62 Myr feature appears in
extinction, when this same procedure is used. We conclude that evidence for a
periodicity at 62 Myr is robust, and evidence for periodicity at approximately
27 Myr is also present, albeit more ambiguous.


title: A 2-generated 2-related group with no non-trivial finite factors

abstract:
  We construct a 2-generated 2-related group without non-trivial finite
factors. That answers a question of J. Button.


title: Green's function of a finite chain and the discrete Fourier transform

abstract:
  A new expression for the Green's function of a finite one-dimensional lattice
with nearest neighbor interaction is derived via discrete Fourier transform.
Solution of the Heisenberg spin chain with periodic and open boundary
conditions is considered as an example. Comparison to Bethe ansatz clarifies
the relation between the two approaches.


title: Some group theory problems

abstract:
  This is a survey of some problems in geometric group theory which I find
interesting. The problems are from different areas of group theory. Each
section is devoted to problems in one area. It contains an introduction where I
give some necessary definitions and motivations, problems and some discussions
of them. For each problem, I try to mention the author. If the author is not
given, the problem, to the best of my knowledge, was formulated by me first.


title: Higher-order theories

abstract:
  We extend our approach to abstract syntax (with binding constructions)
through modules and linearity. First we give a new general definition of arity,
yielding the companion notion of signature. Then we obtain a modularity result
as requested by Ghani and Uustalu (2003): in our setting, merging two
extensions of syntax corresponds to building an amalgamated sum. Finally we
define a natural notion of equation concerning a signature and prove the
existence of an initial semantics for a so-called representable signature
equipped with a set of equations.


title: On weakly convex star-shaped polyhedra

abstract:
  Weakly convex polyhedra which are star-shaped with respect to one of their
vertices are infinitesimally rigid. This is a partial answer to the question
whether every decomposable weakly convex polyhedron is infinitesimally rigid.
The proof uses a recent result of Izmestiev on the geometry of convex caps.


title: Recommending Related Papers Based on Digital Library Access Records

abstract:
  An important goal for digital libraries is to enable researchers to more
easily explore related work. While citation data is often used as an indicator
of relatedness, in this paper we demonstrate that digital access records (e.g.
http-server logs) can be used as indicators as well. In particular, we show
that measures based on co-access provide better coverage than co-citation, that
they are available much sooner, and that they are more accurate for recent
papers.


title: Entangled games are hard to approximate

abstract:
  We establish the first hardness results for the problem of computing the
value of one-round games played by a verifier and a team of provers who can
share quantum entanglement. In particular, we show that it is NP-hard to
approximate within an inverse polynomial the value of a one-round game with (i)
quantum verifier and two entangled provers or (ii) classical verifier and three
entangled provers. Previously it was not even known if computing the value
exactly is NP-hard. We also describe a mathematical conjecture, which, if true,
would imply hardness of approximation to within a constant.
  We start our proof by describing two ways to modify classical multi-prover
games to make them resistant to entangled provers. We then show that a strategy
for the modified game that uses entanglement can be ``rounded'' to one that
does not. The results then follow from classical inapproximability bounds. Our
work implies that, unless P=NP, the values of entangled-prover games cannot be
computed by semidefinite programs that are polynomial in the size of the
verifier's system, a method that has been successful for more restricted
quantum games.


title: The spectral laws of Hermitian block-matrices with large random blocks

abstract:
  We are going to study the limiting spectral measure of fixed dimensional
Hermitian block-matrices with large dimensional Wigner blocks. We are going
also to identify the limiting spectral measure when the Hermitian
block-structure is Circulant. Using the limiting spectral measure of a
Hermitian Circulant block-matrix we will show that the spectral measure of a
Wigner matrix with $k-$weakly dependent entries need not to be the semicircle
law in the limit.


title: Supersymmetric Vector Multiplets in Non-Adjoint Representations of SO(N)

abstract:
  In the conventional formulation of N=1 supersymmetry, a vector multiplet is
supposed to be in the adjoint representation of a given gauge group. We present
a new formulation with a vector multiplet in the non-adjoint representation of
SO(N) gauge group. Our basic algebra is [ T^I, T^J ] = f^{I J K} T^K, [ T^I,
U^i ] = - (T^I)^{i j} U^j, [ U^i, U^j ] = - (T^I)^{i j} T^I, where T^I are the
generators of SO(N), while U^i are the new 'generators' in certain non-adjoint
real representation R of SO(N). We use here the word `generator' in the broader
sense of the word. Such a representation can be any real representation of
SO(N) with the positive definite metric, satisfying (T^I)^{i j} = - (T^I)^{j i}
and (T^I)^{[ i j |} (T^I)^{| k ] l} \equiv 0. The first non-trivial examples
are the spinorial 8_S and conjugate spinorial 8_C representations of SO(8)
consistent with supersymmetry. We further couple the system to chiral
multiplets, and show that a Higgs mechanism can give positive definite (mass)^2
to the new gauge fields for U^i. We show an analogous system working with N=1
supersymmetry in 10D, and thereby N=4 system in 4D interacting with extra
multiplets in the representation R. We also perform superspace reformulation as
an independent confirmation.


title: Pulsar radiation belts and transient radio emission

abstract:
  It is proposed that radiation belts similar to the ones in the planetary
magnetosphere can exist for a pulsar with a relatively long period and a strong
magnetic field. In the belts located in the closed field line region near the
light cylinder relativistic pairs are trapped and maintained at a density
substantially higher than the local Goldreich-Julian corotation density. The
trapped plasma can be supplied and replenished by either direct injection of
relativistic pairs from acceleration of externally-supplied particles in a
dormant outer gap or in situ ionization of the accreted neutral material in the
trapping region. The radiation belts can be disrupted by waves that are excited
in the region as the result of plasma instabilities or emitted from the surface
due to starquakes or stellar oscillations. The disruption can cause an
intermittent particle precipitation toward the star producing radio bursts. It
is suggested that such bursts may be seen as rotating radio transients (RRATs).


title:
The Transit Light Curve Project. VI. Three Transits of the Exoplanet
  TrES-2

abstract:
  Of the nearby transiting exoplanets that are amenable to detailed study,
TrES-2 is both the most massive and has the largest impact parameter. We
present z-band photometry of three transits of TrES-2. We improve upon the
estimates of the planetary, stellar, and orbital parameters, in conjunction
with the spectroscopic analysis of the host star by Sozzetti and co-workers. We
find the planetary radius to be 1.222 +/- 0.038 R_Jup and the stellar radius to
be 1.003 +/- 0.027 R_Sun. The quoted uncertainties include the systematic error
due to the uncertainty in the stellar mass (0.980 +/- 0.062 M_Sun). The timings
of the transits have an accuracy of 25s and are consistent with a uniform
period, thus providing a baseline for future observations with the NASA Kepler
satellite, whose field of view will include TrES-2.


title:
Ferroelectricity driven by the non-centrosymmetric magnetic ordering in
  multiferroic TbMn_2O_5: a first-principles study

abstract:
  The ground state structural, electronic and magnetic properties of
multiferroic TbMn$_2$O$_5$ are investigated via first-principles calculations.
We show that the ferroelectricity in TbMn$_2$O$_5$ is driven by the
non-centrosymmetric magnetic ordering, without invoking the spin-orbit coupling
and non-collinear spins. The {\it intrinsic} electric polarization in this
compound is calculated to be 1187 $nC\cdot$ cm$^{-2}$, an order of magnitude
larger than previously thought.


title:
What it takes to measure a fundamental difference between dark matter
  and baryons: the halo velocity anisotropy

abstract:
  Numerous ongoing experiments aim at detecting WIMP dark matter particles from
the galactic halo directly through WIMP-nucleon interactions. Once such a
detection is established a confirmation of the galactic origin of the signal is
needed. This requires a direction-sensitive detector. We show that such a
detector can measure the velocity anisotropy beta of the galactic halo.
Cosmological N-body simulations predict the dark matter anisotropy to be
nonzero, beta~0.2. Baryonic matter has beta=0 and therefore a detection of a
nonzero beta would be strong proof of the fundamental difference between dark
and baryonic matter. We estimate the sensitivity for various detector
configurations using Monte Carlo methods and we show that the strongest signal
is found in the relatively few high recoil energy events. Measuring beta to the
precision of ~0.03 will require detecting more than 10^4 WIMP events with
nuclear recoil energies greater than 100 keV for a WIMP mass of 100 GeV and a
32S target. This number corresponds to ~10^6 events at all energies. We discuss
variations with respect to input parameters and we show that our method is
robust to the presence of backgrounds and discuss the possible improved
sensitivity for an energy-sensitive detector.


title: Scanning-probe spectroscopy of semiconductor donor molecules

abstract:
  Semiconductor devices continue to press into the nanoscale regime, and new
applications have emerged for which the quantum properties of dopant atoms act
as the functional part of the device, underscoring the necessity to probe the
quantum structure of small numbers of dopant atoms in semiconductors[1-3].
Although dopant properties are well-understood with respect to bulk
semiconductors, new questions arise in nanosystems. For example, the quantum
energy levels of dopants will be affected by the proximity of nanometer-scale
electrodes. Moreover, because shallow donors and acceptors are analogous to
hydrogen atoms, experiments on small numbers of dopants have the potential to
be a testing ground for fundamental questions of atomic and molecular physics,
such as the maximum negative ionization of a molecule with a given number of
positive ions[4,5]. Electron tunneling spectroscopy through isolated dopants
has been observed in transport studies[6,7]. In addition, Geim and coworkers
identified resonances due to two closely spaced donors, effectively forming
donor molecules[8]. Here we present capacitance spectroscopy measurements of
silicon donors in a gallium-arsenide heterostructure using a scanning probe
technique[9,10]. In contrast to the work of Geim et al., our data show
discernible peaks attributed to successive electrons entering the molecules.
Hence this work represents the first addition spectrum measurement of dopant
molecules. More generally, to the best of our knowledge, this study is the
first example of single-electron capacitance spectroscopy performed directly
with a scanning probe tip[9].


title:
Bistability double crossing curve effect in a polariton-laser
  semiconductor microcavity

abstract:
  We report an experimental observation of polaritonic optical bistability of
the laser emission in a planar semiconductor microcavity with a $100\AA$ GaAs
single quantum well in the strong-coupling regime. The bistability curves show
crossings that indicate a competition between a Kerr-like effect induced by the
polariton population and thermal effects. Associated with the bistability,
laser-like emission occurs at the bare cavity mode.


title:
Nontrivial edge coupling from a Dirichlet network squeezing: the case of
  a bent waveguide

abstract:
  In distinction to the Neumann case the squeezing limit of a Dirichlet network
leads in the threshold region generically to a quantum graph with disconnected
edges, exceptions may come from threshold resonances. Our main point in this
paper is to show that modifying locally the geometry we can achieve in the
limit a nontrivial coupling between the edges including, in particular, the
class of $\delta$-type boundary conditions. We work out an illustration of this
claim in the simplest case when a bent waveguide is squeezed.

categories: math-ph cond-mat.mes-hall math.MP math.SP quant-ph


title: Ladder Sandpiles

abstract:
  We study Abelian sandpiles on graphs of the form $G \times I$, where $G$ is
an arbitrary finite connected graph, and $I \subset \Z$ is a finite interval.
We show that for any fixed $G$ with at least two vertices, the stationary
measures $\mu_I = \mu_{G \times I}$ have two extremal weak limit points as $I
\uparrow \Z$. The extremal limits are the only ergodic measures of maximum
entropy on the set of infinite recurrent configurations. We show that under any
of the limiting measures, one can add finitely many grains in such a way that
almost surely all sites topple infinitely often. We also show that the extremal
limiting measures admit a Markovian coding.


title: Possible solution to the $^7$Li problem by the long lived stau

abstract:
  Modification of standard big-bang nucleosynthesis is considered in the
minimal supersymmetric standard model to resolve the excessive theoretical
prediction of the abundance of primordial lithium 7. We focus on the stau as a
next-lightest superparticle, which is long lived due to its small mass
difference with the lightest superparticle. It provides a number of additional
decay processes of $\mathrm{^{7}Li}$ and $\mathrm{^{7}Be}$. A particularly
important process is the internal conversion in the stau-nucleus bound state,
which destroys the $\mathrm{^{7}Li}$ and $\mathrm{^{7}Be}$ effectively. We show
that the modification can lead to a prediction consistent with the observed
abundance of $\mathrm{^{7}Li}$.


title:
Energy and System Size Dependence of Photon Production at Forward
  Rapidities at RHIC

abstract:
  The energy and system size dependence of pseudorapidity ($\eta$) and
multiplicity distributions of photons are measured in the region -2.3 $\leq$
$\eta$ $\leq$ -3.7 for Cu + Cu collisions at $\sqrt{s_{NN}}$ = 200 and 62.4
GeV. Photon multiplicity measurements at forward rapidity have been carried out
using a Photon Multiplicity Detector (PMD) in the STAR experiment. Photons are
found to follow longitudinal scaling for Cu + Cu collisions for 0-10%
centrality. A Comparison of pseudorapidity distributions with HIIJING model is
also presented.


title: Uniqueness thresholds on trees versus graphs

abstract:
  Counter to the general notion that the regular tree is the worst case for
decay of correlation between sets and nodes, we produce an example of a
multi-spin interacting system which has uniqueness on the $d$-regular tree but
does not have uniqueness on some infinite $d$-regular graphs.


title:
Extracting galactic binary signals from the first round of Mock LISA
  Data Challenges

abstract:
  We report on the performance of an end-to-end Bayesian analysis pipeline for
detecting and characterizing galactic binary signals in simulated LISA data.
Our principal analysis tool is the Blocked-Annealed Metropolis Hasting (BAM)
algorithm, which has been optimized to search for tens of thousands of
overlapping signals across the LISA band. The BAM algorithm employs Bayesian
model selection to determine the number of resolvable sources, and provides
posterior distribution functions for all the model parameters. The BAM
algorithm performed almost flawlessly on all the Round 1 Mock LISA Data
Challenge data sets, including those with many highly overlapping sources. The
only misses were later traced to a coding error that affected high frequency
sources. In addition to the BAM algorithm we also successfully tested a Genetic
Algorithm (GA), but only on data sets with isolated signals as the GA has yet
to be optimized to handle large numbers of overlapping signals.


title:
Long Term Simulations Of Astrophysical Jets; Energy Structure and
  Quasi-Periodic Ejection

abstract:
  We have performed self-consistent 2.5-dimensional nonsteady MHD numerical
simulations of jet formation as long as possible, including the dynamics of
accretion disks. Although the previous nonsteady MHD simulations for
astrophysical jets revealed that the characteristics of nonsteady jets are
similar to those of steady jets, the calculation time of these simulations is
very short compared with the time scale of observed jets. Thus we have
investigated long term evolutions of mass accretion rate, mass outflow rate,
jet velocity, and various energy flux. We found that the ejection of jet is
quasi-periodic. The period of the ejection is related to the time needed for
the initial magnetic filed to be twisted to generate toroidal filed. We compare
our results with both the steady state theory and previous 2.5-dimensional
nonsteady MHD simulations.


title:
On Verifying and Engineering the Well-gradedness of a Union-closed
  Family

abstract:
  Current techniques for generating a knowledge space, such as QUERY,
guarantees that the resulting structure is closed under union, but not that it
satisfies wellgradedness, which is one of the defining conditions for a
learning space. We give necessary and sufficient conditions on the base of a
union-closed set family that ensures that the family is well-graded. We
consider two cases, depending on whether or not the family contains the empty
set. We also provide algorithms for efficiently testing these conditions, and
for augmenting a set family in a minimal way to one that satisfies these
conditions.


title:
Global Jacquet-Langlands correspondence, multiplicity one and
  classification of automorphic representations

abstract:
  In this paper we show a local Jacquet-Langlands correspondence for all
unitary irreducible representations. We prove the global Jacquet-Langlands
correspondence in characteristic zero. As consequences we obtain the
multiplicity one and strong multiplicity one theorems for inner forms of GL(n)
as well as a classification of the residual spectrum and automorphic
representations in analogy with results proved by Moeglin-Waldspurger and
Jacquet-Shalika for GL(n).


title:
Solar Magnetic Tracking. I. Software Comparison and Recommended
  Practices

abstract:
  Feature tracking and recognition are increasingly common tools for data
analysis, but are typically implemented on an ad-hoc basis by individual
research groups, limiting the usefulness of derived results when selection
effects and algorithmic differences are not controlled. Specific results that
are affected include the solar magnetic turnover time, the distributions of
sizes, strengths, and lifetimes of magnetic features, and the physics of both
small scale flux emergence and the small-scale dynamo. In this paper, we
present the results of a detailed comparison between four tracking codes
applied to a single set of data from SOHO/MDI, describe the interplay between
desired tracking behavior and parameterization of tracking algorithms, and make
recommendations for feature selection and tracking practice in future work.


title:
Dynamical stability for finite quantum spin chains against a
  time-periodic inhomogeneous perturbation

abstract:
  We investigate dynamical stability of the ground state against a
time-periodic and spatially-inhomogeneous magnetic field for finite quantum XXZ
spin chains. We use the survival probability as a measure of stability and
demonstrate that it decays as $P(t) \propto t^{-1/2}$ under a certain
condition. The dynamical properties should also be related to the level
statistics of the XXZ spin chains with a constant spatially-inhomogeneous
magnetic field. The level statistics depends on the anisotropy parameter and
the field strength. We show how the survival probability depends on the
anisotropy parameter, the strength and frequency of the field.


title: The Magnetic Fields of Classical T Tauri Stars

abstract:
  We report new magnetic field measurements for 14 classical T Tauri stars
(CTTSs). We combine these data with one previous field determination in order
to compare our observed field strengths with the field strengths predicted by
magnetospheric accretion models. We use literature data on the stellar mass,
radius, rotation period, and disk accretion rate to predict the field strength
that should be present on each of our stars according to these magnetospheric
accretion models. We show that our measured field values do not correlate with
the field strengths predicted by simple magnetospheric accretion theory. We
also use our field strength measurements and literature X-ray luminosity data
to test a recent relationship expressing X-ray luminosity as a function of
surface magnetic flux derived from various solar feature and main sequence star
measurements. We find that the T Tauri stars we have observed have weaker than
expected X-ray emission by over an order of magnitude on average using this
relationship. We suggest the cause for this is actually a result of the very
strong fields on these stars which decreases the efficiency with which gas
motions in the photosphere can tangle magnetic flux tubes in the corona.


title: Excedance numbers for permutations in complex reflection groups

abstract:
  Recently, Bagno, Garber and Mansour studied a kind of excedance number on the
complex reflection groups and computed its multidistribution with the number of
fixed points on the set of involutions in these groups. In this note, we
consider the similar problems in more general cases and make a correction of
one result obtained by them.


title:
Failure mechanisms and surface roughness statistics of fractured
  Fontainebleau sandstone

abstract:
  In an effort to investigate the link between failure mechanisms and the
geometry of fractures of compacted grains materials, a detailed statistical
analysis of the surfaces of fractured Fontainebleau sandstones has been
achieved. The roughness of samples of different widths W is shown to be self
affine with an exponent zeta=0.46 +- 0.05 over a range of length scales ranging
from the grain size d up to an upper cut-off length \xi = 0.15 W. This low zeta
value is in agreement with measurements on other sandstones and on sintered
materials. The probability distributions P(delta z,delta h) of the variations
of height over different distances delta z > d can be collapsed onto a single
Gaussian distribution with a suitable normalisation and do not display
multifractal features. The roughness amplitude, as characterized by the
height-height correlation over fixed distances delta z, does not depend on the
sample width, implying that no anomalous scaling of the type reported for other
materials is present. It is suggested, in agreement with recent theoretical
work, to explain these results by the occurence of brittle fracture (instead of
damage failure in materials displaying a higher value of zeta = 0.8).


title:
Optimal Routing for the Gaussian Multiple-Relay Channel with
  Decode-and-Forward

abstract:
  In this paper, we study a routing problem on the Gaussian multiple relay
channel, in which nodes employ a decode-and-forward coding strategy. We are
interested in routes for the information flow through the relays that achieve
the highest DF rate. We first construct an algorithm that provably finds
optimal DF routes. As the algorithm runs in factorial time in the worst case,
we propose a polynomial time heuristic algorithm that finds an optimal route
with high probability. We demonstrate that that the optimal (and near optimal)
DF routes are good in practice by simulating a distributed DF coding scheme
using low density parity check codes with puncturing and incremental
redundancy.


title: Some smooth Finsler deformations of hyperbolic surfaces

abstract:
  Given a closed hyperbolic Riemannian surface, the aim of the present paper is
to describe an explicit construction of smooth deformations of the hyperbolic
metric into Finsler metrics that are not Riemannian and whose properties are
such that the classical Riemannian results about entropy rigidity, marked
length spectrum rigidity and boundary rigidity all fail to extend to the
Finsler category.


title:
Higher genus Gromov-Witten invariants of the Grassmannian, and the
  Pfaffian Calabi-Yau threefolds

abstract:
  We solve Bershadsky-Cecotti-Ooguri-Vafa (BCOV) holomorphic anomaly equation
to determine the higher genus Gromov-Witten invariants ($g \leq 5$) of the
derived equivalent Calabi-Yau threefolds, which are of the appropriate
codimensions in the Grassmannian Gr(2,7) and the Pfaffian Pf(7).


title: La controverse de 1874 entre Camille Jordan et Leopold Kronecker

abstract:
  During the whole of 1874, Camille Jordan and Leopold Kronecker quar- relled
vigorously over the organisation of the theory of bilinear forms. That theory
promised a "general" and "homogeneous" treatment of numerous questions arising
in various 19th-century theoretical contexts, and it hinged on two theorems,
stated independently by Jordan and Weierstrass, that would today be considered
equivalent. It was, however, the perceived difference between those two
theorems that sparked the 1874 controversy. Focusing on this quarrel allows us
to explore the algebraic identity of the polynomial practices of the
manipulations of forms in use before the advent of structural approaches to
linear algebra. The latter approaches identified these practices with methods
for the classification of similar matrices. We show that the prac- tices --
Jordan's canonical reduction and Kronecker's invariant computation -- reflect
identities inseparable from the social context of the time. Moreover, these
practices reveal not only tacit knowledge, local ways of thinking, but also --
in light of a long history tracing back to the work of Lagrange, Laplace, Cau-
chy, and Hermite -- two internal philosophies regarding the significance of
generality which are inseparable from two disciplinary ideals opposing algebra
and arithmetic. By interrogating the cultural identities of such practices,
this study aims at a deeper understanding of the history of linear algebra
without focusing on issues related to the origins of theories or structures.


title:
Probing Inward Motions in Starless Cores Using The HCN J = 1-0 Hyperfine
  Transitions : A Pointing Survey Toward Central Regions

abstract:
  We have carried out a survey toward the central regions of 85 starless cores
in HCN J = 1-0 to study inward motions in the cores. Sixty-four cores were
detected with HCN lines. The infall asymmetry in the HCN spectra is found to be
more prevalent, and more prominent than in any other previously used infall
tracers such as CS J = 2-1, DCO+ J = 2-1, and N2H+ J = 1-0. We found close
relation between the intensities of the HCN and N2H+ lines. This implies that
the HCN is not much depleted in the central regions of the cores. In some
cores, the HCN spectra show different sign of asymmetry from other molecular
lines. A few cores show various signs of asymmetry in individual HCN hyperfine
lines. The distribution of the velocity shift dV of the HCN profiles with
respect to the systemic velocity of the optically thin tracer is found to be
more shifted toward bluer side than those of other infall tracers, indicating
that the HCN traces inward motions more frequently. The dV distribution of each
HCN hyperfine line for all sources is similar. Moreover the dV values obtained
from different HCN hyperfine lines for each source are nearly similar. These
may mean that most of starless cores are in similar kinematic states across the
layers of the cores. We identify 17 infall candidates using all available
indicators such as the velocity shift dV and the blue to red peak intensity
ratio of double peaked profiles for HCN J = 1-0, CS J = 2-1, J = 3-2, DCO+ J =
2-1, and N2H+ J = 1-0. Four of them, L63, L492, L694-2, and L1197 are found to
show higher blue to red ratio in the HCN hyperfine line along the lower
opacity, suggesting that infall speed becomes higher toward the center.


title:
L'identit\'e alg\'ebrique d'une pratique port\'ee par la discussion sur
  l'\'equation \`a l'aide de laquelle on d\'etermine les in\'egalit\'es
  s\'eculaires des plan\`etes (1766-1874)

abstract:
  What did "algebra" mean before the development of the algebraic theories of
the 20th century ? This paper stresses the identities taken by the algebraic
practices developped during the century long discussion around the equation
around the equation of secular inequalities (1766- 1874). In 1874, a strong
controversy on the theory of bilinear and quadratic forms opposed Camille
Jordan and Leopold Kronecker. The arithmetical ideal of Kronecker faced
Jordan's claim for the simplicity of his algebraic canonical form. As the
controversy combined mathematical and historical arguments, it gave rise to the
writing of a history of the methods used by Lagrange, Laplace and Weierstrass
in a century long mathematical discussion around the "equation of secular
inequalities".


title: Controlling statistical properties of stored light

abstract:
  Statistical properties of outgoing light pulses are studies after they have
been stored in a medium of atoms in the tripod configuration. A generalized
Hong-Ou-Mandel interference, storing of squeezed states and homodyne signal
analysis are discussed in the context of their dependence on the parameters of
the control fields used for light storage and release.


title: Some results on the Zeeman topology

abstract:
  In a 1967 paper, Zeeman proposed a new topology for Minkowski spacetime,
physically motivated but much more complicated than the standard one. Here a
detailed study is given of some properties of the Zeeman topology which had not
been considered at the time. The general setting refers to Minkowski spacetime
of any dimension k+1. In the special case k=1, a full characterization is
obtained for the compact subsets of spacetime; moreover, the first homotopy
group is shown to be nontrivial.


title: Asymmetry of the Hamiltonian and the Tolman's length

abstract:
  Using the canonical transformation of the order parameter which restores the
Ising symmetry of the Hamiltonian we derive the expression for the Tolman
length as a sum of two terms. One of them is the term generated by the
fluctuations of the order parameter the other one is due to the entropy. The
leading singular behavior of the Tolman length near the critical point is
analyzed. The obtained results are in correspondence with that of M.A.
Anisimov, Phys. Rev. Lett., \textbf{98} 035702 (2007).


title: Formation of Ultracold Heteronuclear Dimers in Electric Fields

abstract:
  The formation of ultracold molecules via stimulated emission followed by a
radiative deexcitation cascade in the presence of a static electric field is
investigated. By analyzing the corresponding cross sections, we demonstrate the
possibility to populate the lowest rotational excitations via photoassociation.
The modification of the radiative cascade due to the electric field leads to
narrow rotational state distributions in the vibrational ground state. External
fields might therefore represent an additional valuable tool towards the
ultimate goal of quantum state preparation of molecules.


title:
Generalized MICZ-Kepler Problems and Unitary Highest Weight Modules --
  II

abstract:
  For each integer $n\ge 2$, we demonstrate that a 2n-dimensional generalized
MICZ-Kepler problem has an $\widetilde{\mr{Spin}}(2, 2n+1)$ dynamical symmetry
which extends the manifest $\mr{Spin}(2n)$ symmetry. The Hilbert space of bound
states is shown to form a unitary highest weight $\widetilde{\mr{Spin}}(2,
2n+1)$-module which occurs at the first reduction point in the
Enright-Howe-Wallach classification diagram for the unitary highest weight
modules. As a byproduct, we get a simple geometric realization for such a
unitary highest weight $\widetilde{\mr{Spin}}(2, 2n+1)$-module.


title: Quantum Parrondo's game with random strategies

abstract:
  We present a quantum implementation of Parrondo's game with randomly switched
strategies using 1) a quantum walk as a source of ``randomness'' and 2) a
completely positive (CP) map as a randomized evolution. The game exhibits the
same paradox as in the classical setting where a combination of two losing
strategies might result in a winning strategy. We show that the CP-map scheme
leads to significantly lower net gain than the quantum walk scheme.


title:
Improving Stellar and Planetary Parameters of Transiting Planet Systems:
  The Case of TrES-2

abstract:
  We report on a spectroscopic determination of the atmospheric parameters and
chemical abundance of the parent star of the recently discovered transiting
planet {TrES-2}. A detailed LTE analysis of a set of \ion{Fe}{1} and
\ion{Fe}{2} lines from our Keck spectra yields $T_\mathrm{eff} = 5850\pm 50$ K,
$\log g = 4.4\pm 0.1$, and [Fe/H] $= -0.15\pm 0.10$. Several independent checks
(e.g., additional spectroscopy, line-depth ratios) confirm the reliability of
our spectroscopic $T_\mathrm{eff}$ estimate. The mass and radius of the star,
needed to determine the properties of the planet, are traditionally inferred by
comparison with stellar evolution models using $T_\mathrm{eff}$ and some
measure of the stellar luminosity, such as the spectroscopic surface gravity
(when a trigonometric parallax is unavailable, as in this case). We apply here
a new method in which we use instead of $\log g$ the normalized separation
$a/R_\star$ (related to the stellar density), which can be determined directly
from the light curves of transiting planets with much greater precision. With
the $a/R_\star$ value from the light curve analysis of Holman et al.
\citeyearpar{holman07b} and our $T_\mathrm{eff}$ estimate we obtain $M_\star =
0.980\pm0.062 M_\odot$ and $R_\star = 1.000_{-0.033}^{+0.036} R_\odot$, and an
evolutionary age of $5.1^{+2.7}_{-2.3}$ Gyr, in good agreement with other
constraints based on the strength of the emission in the \ion{Ca}{2} H & K line
cores, the Lithium abundance, and rotation. The new stellar parameters yield
improved values for the planetary mass and radius of $M_p = 1.198 \pm 0.053
M_\mathrm{Jup}$ and $R_p = 1.220^{+0.045}_{-0.042} R_\mathrm{Jup}$, confirming
that {TrES-2} is the most massive among the currently known nearby ($d\lesssim
300$ pc) transiting hot Jupiters. [Abridged]


title: Multiple scalar particle decay and perturbation generation

abstract:
  We study the evolution of the universe which contains a multiple number of
non-relativistic scalar fields decaying into both radiation and pressureless
matter. We present a powerful analytic formalism to calculate the matter and
radiation curvature perturbations, and find that our analytic estimates agree
with full numerical results within an error of less than one percent. Also we
discuss the isocurvature perturbation between matter and radiation components,
which may be detected by near future cosmological observations, and point out
that it crucially depends on the branching ratio of the decay rate of the
scalar fields and that it is hard to make any model independent predictions.


title:
Fidelity approach to quantum phase transitions: finite size scaling for
  quantum Ising model in a transverse field

abstract:
  We analyze the scaling parameter, extracted from the fidelity for two
different ground states, for the one-dimensional quantum Ising model in a
transverse field near the critical point. It is found that, in the
thermodynamic limit, the scaling parameter is singular, and the derivative of
its logarithmic function with respect to the transverse field strength is
logarithmically divergent at the critical point. The scaling behavior is
confirmed numerically by performing a finite size scaling analysis for systems
of different sizes, consistent with the conformal invariance at the critical
point. This allows us to extract the correlation length critical exponent,
which turns out to be universal in the sense that the correlation length
critical exponent does not depend on either the anisotropic parameter or the
transverse field strength.


title: Experimental Decoy Quantum Key Distribution Up To 130KM Fiber

abstract:
  Decoy State Quantum Key Distribution (QKD), being capable of beating PNS
attack and uncon- ditionally secure, have become an attractive one recently.
But, in many QKD systems, disturbances of transmission channel make quantum bit
error rate (QBER) increase which limits both security distance and key bit rate
of real-life decoy state QKD systems. We demonstrate the two-intensity decoy
QKD with one-way Faraday-Michelson phase modulation system, which is free of
channel dis- turbance and keeps interference fringe visibility (99%) long
period, near 130KM single mode optical fiber in telecom (1550 nm) wavelength.
This is longest distance fiber decoy state QKD system based on two intensity
protocol.


title:
The Star-forming Region NGC 346 in the Small Magellanic Cloud with
  Hubble Space Telescope ACS Observations. II. Photometric Study of the
  Intermediate-Age Star Cluster BS 90

abstract:
  We present the results of our investigation of the intermediate-age star
cluster BS 90, located in the vicinity of the HII region N 66 in the SMC,
observed with HST/ACS. The high-resolution data provide a unique opportunity
for a very detailed photometric study performed on one of the rare
intermediate-age rich SMC clusters. The complete set of observations is
centered on the association NGC 346 and contains almost 100,000 stars down to V
~28 mag. In this study we focus on the northern part of the region, which
covers almost the whole stellar content of BS 90. We construct its stellar
surface density profile and derive structural parameters. Isochrone fits on the
CMD of the cluster results in an age of about 4.5 Gyr. The luminosity function
is constructed and the present-day mass function of BS 90 has been obtained
using the mass-luminosity relation, derived from the isochrone models. We found
a slope between -1.30 and -0.95, comparable or somewhat shallower than a
typical Salpeter IMF. Examination of the radial dependence of the mass function
shows a steeper slope at larger radial distances, indicating mass segregation
in the cluster. The derived half-mass relaxation time of 0.95 Gyr suggests that
the cluster is mass segregated due to its dynamical evolution. From the
isochrone model fits we derive a metallicity for BS 90 of [Fe/H]=-0.72, which
adds an important point to the age-metallicity relation of the SMC. We discuss
our findings on this relation in comparison to other SMC clusters.


title:
Impact of dimensionless numbers on the efficiency of MRI-induced
  turbulent transport

abstract:
  The magneto-rotational instability is presently the most promising source of
turbulent transport in accretion disks. However, some important issues still
need to be addressed to quantify the role of MRI in disks; in particular no
systematic investigation of the role of the physical dimensionless parameters
of the problem on the dimensionless transport has been undertaken yet. First,
we complete existing investigations on the field strength dependence by showing
that the transport in high magnetic pressure disks close to marginal stability
is highly time-dependent and surprisingly efficient. Second, we bring to light
a significant dependence of the global transport on the magnetic Prandtl
number, with $\alpha\propto Pm^\delta$ for the explored range: $0.12<Pm<8$ and
$200<Re<6400$ ($\delta$ being in the range 0.25 to 0.5). We show that the
dimensionless transport is not correlated to the dimensionless linear growth
rate, contrarily to a largely held expectation. More generally, these results
stress the need to control dissipation processes in astrophysical simulations.


title: Statistics of neutrinos and the double beta decay

abstract:
  We assume that the Pauli exclusion principle is violated for neutrinos, and
thus, neutrinos obey at least partly the Bose-Einstein statistics. The
parameter sin^2 chi is introduced that characterizes the bosonic (symmetric)
fraction of the neutrino wave function. Consequences of the violation of the
exclusion principle for the two-neutrino double beta decays are considered.
This violation strongly changes the rates of the decays and modifies the energy
and angular distributions of the emitted electrons. Pure bosonic neutrinos are
excluded by the present data. In the case of partly bosonic (or
mixed-statistics) neutrinos the analysis of the existing data allows to put the
conservative upper bound sin^2 chi < 0.6. The sensitivity of future
measurements of the two-neutrino double beta decay to sin^2 chi is evaluated.


title:
Renormalization group flows and quantum phase transitions: fidelity
  versus entanglement

abstract:
  We compare the roles of fidelity and entanglement in characterizing
renormalization group flows and quantum phase transitions. It turns out that
the scaling parameter extracted from fidelity for different ground states
succeeds to capture nontrivial information including stable and unstable fixed
points, whereas the von Neumann entropy as a bipartite entanglement measure (or
equivalently, majorization relations satisfied by the spectra of the reduced
density matrix along renormalization group flows) often fails, as far as the
intrinsic irreversibility-information loss along renormalization group flows-is
concerned. We also clarify an intimate connection between the von Neumman
entropy, majorization relations, and fidelity. The relevance to Zamolodchikov's
c theorem is indicated.


title: Background study for the pn-CCD detector of CERN Axion Solar Telescope

abstract:
  The CERN Axion Solar Telescope (CAST) experiment searches for axions from the
Sun converted into photons with energies up to around 10 keV via the inverse
Primakoff effect in the high magnetic field of a superconducting Large Hadron
Collider (LHC) prototype magnet. A backside illuminated pn-CCD detector in
conjunction with an X-ray mirror optics is one of the three detectors used in
CAST to register the expected photon signal. Since this signal is very rare and
different background components (environmental gamma radiation, cosmic rays,
intrinsic radioactive impurities in the set-up, ...) entangle it, a detailed
study of the detector background has been undertaken with the aim to understand
and further reduce the background level of the detector. The analysis is based
on measured data taken during the Phase I of CAST and on Monte Carlo
simulations of different background components. This study will show that the
observed background level (at a rate of (8.00+-0.07)10^-5 counts/cm^2/s/keV
between 1 and 7 keV) seems to be dominated by the external gamma background due
to usual activities at the experimental site, while radioactive impurities in
the detector itself and cosmic neutrons could make just smaller contribution.


title: Tables of graphs of binary and ternary sequences differentiation

abstract:
  Let $x$ be a cyclic sequence of $n$ elements of the finite field
$\mathbb{F}_q$ (the first element immediately follows the $n$-th one). Let us
define the operation $\Delta$ as the transition from $x$ to the sequence of
differences of the neighbouring elements from $x$. The aim of this work is to
give graphs of the dynamic system $\Delta$ for $q=2$, $n\le 300$ and $q=3$,
$n\le 150$. These results enable us to define more precisely the Arnold
hypotheses and to prove them.


title: The pseudo-effective cone of a non-K\"ahlerian surface and applications

abstract:
  We describe the positive cone and the pseudo-effective cone of a
non-K\"ahlerian surface. We use these results for two types of applications:
  - Describe the set $\sigma(X)$ of possible total Ricci scalars associated
with Gauduchon metrics of fixed volume 1 on a fixed non-K\"ahhlerian surface,
and decide whether the assignment $X\mapsto\sigma(X)$ is a deformation
invariant.
  - Study the stability of the canonical extension
  $$0\to {\cal K}_X\to {\cal A}\to{\cal O}_X\to 0$$ of a class VII surface $X$
with positive $b_2$. This extension plays an important role in our strategy to
prove the GSS conjecture using gauge theoretical methods.


title:
Optimizing future imaging survey of galaxies to confront dark energy and
  modified gravity models

abstract:
  We consider the extent to which future imaging surveys of galaxies can
distinguish between dark energy and modified gravity models for the origin of
the cosmic acceleration. Dynamical dark energy models may have similar
expansion rates as models of modified gravity, yet predict different growth of
structure histories. We parameterize the cosmic expansion by the two
parameters, $w_0$ and $w_a$, and the linear growth rate of density fluctuations
by Linder's $\gamma$, independently. Dark energy models generically predict
$\gamma \approx 0.55$, while the DGP model $\gamma \approx 0.68$. To determine
if future imaging surveys can constrain $\gamma$ within 20 percent (or
$\Delta\gamma<0.1$), we perform the Fisher matrix analysis for a weak lensing
survey such as the on-going Hyper Suprime-Cam (HSC) project. Under the
condition that the total observation time is fixed, we compute the Figure of
Merit (FoM) as a function of the exposure time $\texp$. We find that the
tomography technique effectively improves the FoM, which has a broad peak
around $\texp\simeq {\rm several}\sim 10$ minutes; a shallow and wide survey is
preferred to constrain the $\gamma$ parameter. While $\Delta\gamma < 0.1$
cannot be achieved by the HSC weak-lensing survey alone, one can improve the
constraints by combining with a follow-up spectroscopic survey like WFMOS
and/or future CMB observations.


title:
Pseudo-localization of singular integrals and noncommutative
  Calderon-Zygmund theory

abstract:
  In this paper we obtain the weak type (1,1) boundedness of Calderon-Zygmund
operators acting over operator-valued functions. Our main tools for its
solution are a noncommutative form of Calderon-Zygmund decomposition in
conjunction with a pseudo-localization principle for singular integrals, which
is new even in the classical setting and of independent interest. Perhaps
because of the hidden role of pseudo-localization and almost orthogonality,
this problem has remained open for quite some time. We also consider
Calderon-Zygmund operators associated to certain operator-valued kernels.


title: Recursive weighted treelike networks

abstract:
  We propose a geometric growth model for weighted scale-free networks, which
is controlled by two tunable parameters. We derive exactly the main
characteristics of the networks, which are partially determined by the
parameters. Analytical results indicate that the resulting networks have
power-law distributions of degree, strength, weight and betweenness, a
scale-free behavior for degree correlations, logarithmic small average path
length and diameter with network size. The obtained properties are in agreement
with empirical data observed in many real-life networks, which shows that the
presented model may provide valuable insight into the real systems.


title: Selective cloning of Gaussian states by linear optics

abstract:
  We investigate the performances of a selective cloning machine based on
linear optical elements and Gaussian measurements, which allows to clone at
will one of the two incoming input states. This machine is a complete
generalization of a 1 to 2 cloning scheme demonstrated by U. L. Andersen et al.
[Phys. Rev. Lett. vol. 94, 240503 (2005)]. The input-output fidelity is studied
for generic Gaussian input state and the effect of non-unit quantum efficiency
is also taken into account. We show that if the states to be cloned are
squeezed states with known squeezing parameter, then the fidelity can be
enhanced using a third suitable squeezed state during the final stage of the
cloning process. A binary communication protocol based on the selective cloning
machne is also discussed.


title: A link polynomial via a vertex-edge-face state model

abstract:
  We construct a 2-variable link polynomial, called $W_L$, for classical links
by considering simultaneously the Kauffman state models for the Alexander and
for the Jones polynomials. We conjecture that this polynomial is the product of
two 1-variable polynomials, one of which is the Alexander polynomial.
  We refine $W_L$ to an ordered set of 3-variable polynomials for those links
in 3-space which contain a Hopf link as a sublink.


title:
Characteristics of phonon transmission across epitaxial interfaces: a
  lattice dynamic study

abstract:
  Phonon transmission across epitaxial interfaces is studied within the lattice
dynamic approach. The transmission shows weak dependence on frequency for the
lattice wave with a fixed angle of incidence. The dependence on azimuth angle
is found to be related to the symmetry of the boundary interface. The
transmission varies smoothly with the change of the incident angle. A critical
angle of incidence exists when the phonon is incident from the side with large
group velocities to the side with low ones. No significant mode conversion is
observed among different acoustic wave branches at the interface, except when
the incident angle is near the critical value. Our theoretical result of the
Kapitza conductance $G_{K}$ across the Si-Ge (100) interface at temperature
$T=200 $K is $4.6\times10^{8} {\rm WK}^{-1}{\rmm}^{-2}$. A scaling law $G_K
\propto T^{2.87}$ at low temperature is also reported. Based on the features of
transmission obtained within lattice dynamic approach, we propose a simplified
formula for thermal conductanceacross the epitaxial interface. A reasonable
consistency is found between the calculated values and the experimentally
measured ones.


title:
How a "Hit" is Born: The Emergence of Popularity from the Dynamics of
  Collective Choice

abstract:
  In recent times there has been a surge of interest in seeking out patterns in
the aggregate behavior of socio-economic systems. One such domain is the
emergence of statistical regularities in the evolution of collective choice
from individual behavior. This is manifested in the sudden emergence of
popularity or "success" of certain ideas or products, compared to their
numerous, often very similar, competitors. In this paper, we present an
empirical study of a wide range of popularity distributions, spanning from
scientific paper citations to movie gross income. Our results show that in the
majority of cases, the distribution follows a log-normal form, suggesting that
multiplicative stochastic processes are the basis for emergence of popular
entities. This suggests the existence of some general principles of complex
organization leading to the emergence of popularity. We discuss the theoretical
principles needed to explain this socio-economic phenomenon, and present a
model for collective behavior that exhibits bimodality, which has been observed
in certain empirical popularity distributions.


title: Effective Field Theory, Renormalizability and Extra Dimensions

abstract:
  We discuss in this paper two ways of defining the concept of "effective field
theory": effective field theory defined by low energy effectiveness and
effective field theory defined by 4D effectiveness out of higher dimensions. We
argue that these two views are actually equivalent, that effective field
theories at low energy can in fact be regarded as field theories of higher
dimensions confined on a 4D spcaetime. We examine this idea through comparing
two different regularization schemes: Momentum Cutoff and Dimensional
Regularization, and through analyzing how fields can be localized on branes.


title:
Superfluid-Insulator Transition of Strongly Interacting Fermi Gases in
  Optical Lattices

abstract:
  We study a quantum phase transition between fermion superfluid (SF) and band
insulator (BI) of fermions in optical lattices. The destruction of the band
insulator is driven by the energy gain in promoting fermions from valance band
to various conducting bands to form Cooper pairs. We show that the transition
must take place in rather shallow lattice height, $V_{o}/E_{R}$ between 2.23
and 4.14. The latter is the prediction of mean field theory while the former is
the value for opening a band gap. As one moves across resonance to the molecule
side, the SF-BI transition evolves into the SF-Mott insulator transition of
bosonic molecules. We shall also present the global phase diagram for
SF-Insulator transition for the BCS-BEC family.


title:
Why are accreting T Tauri stars observed to be less luminous in X-rays
  than non-accretors?

abstract:
  Accreting T Tauri stars are observed to be less luminous in X-rays than
non-accretors, an effect that has been detected in various star forming
regions. To explain this we have combined, for the first time, a radiative
transfer code with an accretion model that considers magnetic fields
extrapolated from surface magnetograms obtained from Zeeman-Doppler imaging.
Such fields consist of compact magnetic regions close to the stellar surface,
with extended field lines interacting with the disc. We study the propagation
of coronal X-rays through the magnetosphere and demonstrate that they are
strongly absorbed by the dense gas in accretion columns. The reduction in the
observed X-ray emission depends on the field geometry, which may explain why
accreting T Tauri stars show a larger scatter in their observed X-ray
luminosity compared to non-accreting stars.


title: Geometry of PT-symmetric quantum mechanics

abstract:
  Recently, much research has been carried out on Hamiltonians that are not
Hermitian but are symmetric under space-time reflection, that is, Hamiltonians
that exhibit PT symmetry. Investigations of the Sturm-Liouville eigenvalue
problem associated with such Hamiltonians have shown that in many cases the
entire energy spectrum is real and positive and that the eigenfunctions form an
orthogonal and complete basis. Furthermore, the quantum theories determined by
such Hamiltonians have been shown to be consistent in the sense that the
probabilities are positive and the dynamical trajectories are unitary. However,
the geometrical structures that underlie quantum theories formulated in terms
of such Hamiltonians have hitherto not been fully understood. This paper
studies in detail the geometric properties of a Hilbert space endowed with a
parity structure and analyses the characteristics of a PT-symmetric Hamiltonian
and its eigenstates. A canonical relationship between a PT-symmetric operator
and a Hermitian operator is established. It is shown that the quadratic form
corresponding to the parity operator, in particular, gives rise to a natural
partition of the Hilbert space into two halves corresponding to states having
positive and negative PT norm. The indefiniteness of the norm can be
circumvented by introducing a symmetry operator C that defines a positive
definite inner product by means of a CPT conjugation operation.


title: An Exact Bosonization Rule for c=1 Noncritical String Theory

abstract:
  We construct a string field theory for c=1 noncritical strings using the loop
variables as the string field. We show how one can express the nonrelativistic
free fermions which describes the theory, in terms of these string fields.


title: On maximal entanglement between two pairs in four-qubit pure states

abstract:
  We show that the state with the highest known average two-particle von
Neumann entanglement entropy proposed by Sudbery and one of the authors gives a
local maximum of this entropy. We also show that this is not the case for an
alternative highly entangled state proposed by Brown et al.


title: The Rotation of Sub-Populations in omega Centauri

abstract:
  We present the first result of the Ital-FLAMES survey of red giant branch
(RGB) stars in omega Cen. Radial velocities with a precision of ~0.5 km/s are
presented for 650 members of omega Cen observed with FLAMES-Giraffe at the Very
Large Telescope. We found that stars belonging to the metal -poor (RGB-MP),
metal-intemediate (RGB-MInt) and metal-rich (RGB-a) sub -populations of Omega
Cen are all compatible with having the same rotational pattern. Our results
appear to contradict past findings by Norris et al., who could not detect any
rotational signature for metal -rich stars. The slightly higher precision of
the present measurements and the much larger sample size, especially for the
metal-richer stars, appear as the most likely explanation for this discrepancy.
The result presented here weakens the body of evidence in favour of a merger
event in the past history of omega Cen.


title: Using Access Data for Paper Recommendations on ArXiv.org

abstract:
  This thesis investigates in the use of access log data as a source of
information for identifying related scientific papers. This is done for
arXiv.org, the authority for publication of e-prints in several fields of
physics.
  Compared to citation information, access logs have the advantage of being
immediately available, without manual or automatic extraction of the citation
graph. Because of that, a main focus is on the question, how far user behavior
can serve as a replacement for explicit meta-data, which potentially might be
expensive or completely unavailable. Therefore, we compare access, content, and
citation-based measures of relatedness on different recommendation tasks. As a
final result, an online recommendation system has been built that can help
scientists to find further relevant literature, without having to search for
them actively.


title: Fourier Analysis of Biological Evolution: Concept of Selection Moment

abstract:
  Secondary structure elements of many protein families exhibit differential
conservation on their opposing faces. Amphipathic helices and beta-sheets by
definition possess this property, and play crucial functional roles. This type
of evolutionary trajectory of a protein family is usually critical to the
functions of the protein family, as well as in creating functions within
subfamilies. That is, differential conservation maintains properties of a
protein structure related to its orientation, and that are important in
packing, recognition, and catalysis. Here I define and formulate a new concept,
called the selection moment, that detects this evolutionary process in protein
sequences. A treatment of its various applications is detailed.


title: Relativistic corrections of order m\alpha^6 to the two-center problem

abstract:
  Effective potentials of the relativistic m\alpha^6 order correction for the
ground state of the Coulomb two-center problem are calculated. They can be used
to evaluate the relativistic contribution of that order to the energies of
hydrogen molecular ions or metastable states of the antiprotonic helium atom,
where precision spectroscopic data are available. In our studies we use the
variational expansion based on randomly chosen exponents that permits to
achieve high numerical accuracy.


title: Impurity Scattering and Mott's Formula in Graphene

abstract:
  We present calculations of the thermal and electric linear response in
graphene, including disorder in the self-consistent t-matrix approximation. For
strong impurity scattering, near the unitary limit, the formation of a band of
impurity states near the Fermi level leads to that Mott's relation holds at low
temperature. For higher temperatures, there are strong deviations due to the
linear density of states. The low-temperature thermopower is proportional to
the inverse of the impurity potential and the inverse of the impurity density.
Information about impurity scattering in graphene can be extracted from the
thermopower, either measured directly, or extracted via Mott's relation from
the electron-density dependence of the electric conductivity.


title: Group-theoretic Description of Riemannian Spaces

abstract:
  It is shown that a locally geometrical structure of arbitrarily curved
Riemannian space is defined by a deformed group of its diffeomorphisms


title: Are Bosonic Replicas Faulty?

abstract:
  Motivated by the ongoing discussion about a seeming asymmetry in the
performance of fermionic and bosonic replicas, we present an exact,
nonperturbative approach to zero-dimensional replica field theories belonging
to the broadly interpreted "beta=2" Dyson symmetry class. We then utilise the
formalism developed to demonstrate that the bosonic replicas do correctly
reproduce the microscopic spectral density in the QCD inspired chiral Gaussian
unitary ensemble. This disproves the myth that the bosonic replica field
theories are intrinsically faulty.

categories: cond-mat.dis-nn hep-th math-ph math.MP nlin.SI


title: Direct simulation for a homogenous gas

abstract:
  A probabilistic analysis of the direct simulation of a homogeneous gas is
given. A hierarchy of equations similar to the BBGKY hierarchy for the reduced
probability densities is derived. By invoking the molecular chaos assumption,
an equation similar to the Boltzmann equation for the single particle
probability density and the corresponding H-theorem is derived.


title: An absorption origin for the soft excess in Seyfert 1 AGN

abstract:
  (abridged) The soft excess seen in the X-ray spectra of many high mass
accretion rate AGN can be well modelled by reflection from a partially ionised
accretion disc. However, the derived parameters are often extreme, both in
terms of the underlying spacetime and the reflection geometry, and these models
require that the disc is far from hydrostatic equilibrium. An alternative model
uses similarly partially ionised, velocity smeared material but seen in
absorption, though again the derived velocities are extreme, requiring magnetic
driving (in the jet?) rather than a simple line driven disc wind. We find that
while both models give comparably good fits to XMM--Newton data, we favour the
absorption model as, unlike reflection, all the derived spectral indices are
soft. This is as expected by analogy with the correspondingly high mass
accretion rate stellar mass black holes. Furthermore, these X-ray spectra are
consistent with a one--to--one mapping between AGN type and spectral state,
with NLS1's having softer spectra corresponding to the very high state, while
the broad line AGN have Gamma~2 as expected for the high/soft state. We also
use the simultaneous OM data to derive the ratio of disc to total accretion
power which is another tracer of spectral state in X-ray binaries. This does
not always show that the disc in NLS1's contributes less than 80 per cent of
the total power, as expected for a very high state. We suggest that this is an
artifact of the standard disc models used to determine the disc luminosity in
our fits. The disc seen in the very high state of black hole binaries is often
observed to be distorted from the standard shape, and a similar effect in
NLS1's could recover the correspondance between black hole binary spectral
state and AGN type.


title:
The XMM-SSC survey of hard-spectrum XMM-Newton sources 1: optically
  bright sources

abstract:
  We present optical and X-ray data for a sample of serendipitous XMM-Newton
sources that are selected to have 0.5-2 keV vs 2-4.5 keV X-ray hardness ratios
which are harder than the X-ray background. The sources have 2-4.5 keV X-ray
flux >= 10^-14 cgs, and in this paper we examine a subsample of 42 optically
bright (r < 21) sources; this subsample is 100 per cent spectroscopically
identified. All but one of the optical counterparts are extragalactic, and we
argue that the single exception, a Galactic M star, is probably a coincidental
association. The X-ray spectra are consistent with heavily absorbed power laws
(21.8 < log NH < 23.4), and all of them appear to be absorbed AGN. The majority
of the sources show only narrow emission lines in their optical spectra,
implying that they are type-2 AGN. Only a small fraction of the sources (7/42)
show broad optical emission lines, and all of these have NH < 10^23 cm^-2. This
implies that ratios of X-ray absorption to optical/UV extinction equivalent to
> 100 times the Galactic gas-to-dust ratio are rare in AGN absorbers (at most a
few percent of the population), and may be restricted to broad absorption-line
QSOs. Seven objects appear to have an additional soft X-ray component in
addition to the heavily absorbed power law. We consider the implications of our
results in the light of the AGN unified scheme. We find that the soft
components in narrow-line objects are consistent with the unified scheme
provided that > 4 per cent of broad-line AGN have ionised absorbers that
attenuate their soft X-ray flux by >50 per cent. In at least one of the X-ray
absorbed, broad-line AGN in our sample the X-ray spectrum requires an ionised
absorber, consistent with this picture.


title: Superconducting state of excitonic insulator

abstract:
  A state of an excitonic insulator with the electric current is studied.
Initially, in the metallic phase, the electrons and holes are assumed to be
moving in the opposite directions, so as the electric current exists. This
state is supported by an external condition (the specimen is in an electric
circuit with the current). When the temperature decreases, the transition to
the ordering state due to formation of the electron--hole pairs is possible
(similar to the ordinary state of the excitonic insulator). The properties of
the state at zero temperature are investigated. The spectrum of elementary
excitations has a gap, and so the conclusion can be made that obtained state is
superconducting one. Thus, depending on the external conditions, excitonic
insulator behaves itself like the insulator or superconductor. That is correct
in the limit of strong overlapping of the electron--hole pairs.


title:
Entanglement fidelity and measurement of entanglement preserving in
  quantum processes

abstract:
  The entanglement fidelity provides a measure of how well the entanglement
between two subsystems is preserved in a quantum process. By using a simple
model we show that in some cases this quantity in its original definition fails
in the measurement of the entanglement preserving. On the contrary, the
modified entanglement fidelity, obtained by using a proper local unitary
transformation on a subsystem, is shown to exhibit the behavior similar to that
of the concurrence in the quantum evolution.


title: Spin dephasing due to a random Berry phase

abstract:
  We investigate relaxation and dephasing of an electron spin confined in a
semiconductor quantum dot and subject to spin-orbit coupling. Even in vanishing
magnetic field, B = 0, slow noise coupling to the electron's orbital degree of
freedom leads to dephasing of the spin due to a random, in general non-Abelian
Berry phase acquired by the spin. For illustration we first present a simple
quasiclassical description, then consider a model with 2 orbital states only,
and finally present a perturbative quantum treatment appropriate for an
electron in a realistic (roughly parabolic, not too strongly confining) quantum
dot. We further compare the effect of different sources of noise. While at
large magnetic fields phonons dominate the relaxation processes, at low fields
electron-hole excitations and possibly 1/f noise may dominate.


title: The Vogel-Fulcher-Tamman law in the elastic theory of glass transition

abstract:
  We propose that the origin of the Vogel-Fulcher-Tammann law is the increase
of the range of elastic interaction between local relaxation events in a
liquid. In this picture, we discuss the origin of cooperativity of relaxation,
the absence of divergence of relaxation time at a finite temperature and the
crossover to a more Arrhenius behaviour at low temperature.


title: On the alpha-Amenability of Hypergroups

abstract:
  Let $UC(K)$ denote the Banach space of all bounded uniformly continuous
functions on a hypergroup $K$. The main results of this article concern on the
$\alpha$-amenability of $UC(K)$ and quotients and products of hypergroups. It
is also shown that a Sturm-Liouville hypergroup with a positive index is
$\alpha$-amenable if and only if $\alpha=1$.


title: Liquid elasticity length and universal dynamic crossovers

abstract:
  We discuss two main universal dynamic crossovers in a liquid that correspond
to relaxation times of 1 ps and $10^{-7}-10^{-6}$ s. We introduce the concept
of liquid elasticity length $d_{el}$. At room temperature, $d_{el}$ is several
\AA in water and increases to 0.01 mm in honey and 1 mm in tar. We show that on
temperature decrease, $d_{el}$ crosses the fundamental lengths of the system,
medium-range order $d_m$ and system size $L$. We discuss how $d_{el}=d_m$ and
$d_{el}=L$ correspond to the two dynamic crossovers.


title:
On Loops in the Hyperbolic Locus of the Complex H\'enon Map and Their
  Monodromies

abstract:
  We prove John Hubbard's conjecture on the topological complexity of the
hyperbolic horseshoe locus of the complex H\'enon map. Indeed, we show that
there exist several non-trivial loops in the locus which generate infinitely
many mutually different monodromies. Our main tool is a rigorous computational
algorithm for verifying the uniform hyperbolicity of chain recurrent sets. In
addition, we show that the dynamics of the real H\'enon map is completely
determined by the monodromy of a certain loop, providing the parameter of the
map is contained in the hyperbolic horseshoe locus of the complex H\'enon map.


title:
Kondo effect in transport through molecules adsorbed on metal surfaces:
  from Fano dips to Kondo peaks

abstract:
  The Kondo effect observed in recent STM experiments on transport through CoPc
and TBrPP-Co molecules adsorbed on Au(111) and Cu(111) surfaces, respectively,
is discussed within the framework of a simple model (Phys. Rev. Lett. {\bf 97},
076806 (2006)). It is shown that, in the Kondo regime and by varying the
adequate model parameters, it is possible to produce a crossover from a
conductance Kondo peak (CoPc) to a conductance Fano dip (TBrPP-Co). In the case
of TBrPP-Co/Cu(111) we show that the model reproduces the changes in the shape
of the Fano dip, the raising of the Kondo temperature and shifting to higher
energies of the dip minimum when the number of nearest neighbors molecules is
lowered. These features are in line with experimental observations indicating
that our simple model contains the essential physics underlying the transport
properties of such complex molecules.


title:
Canonical Deformed Groups of Diffeomorphisms and Finite Parallel
  Transports in Riemannian Spaces

abstract:
  We show that finite parallel transports of vectors in Riemannian spaces,
determined by the multiplication law in the deformed groups of diffeomorphisms,
and sequences of infinitesimal parallel transports of vectors along geodesics
are equivalent.


title: Entanglement in the quantum Ising model

abstract:
  We study the asymptotic scaling of the entanglement of a block of spins for
the ground state of the one-dimensional quantum Ising model with transverse
field. When the field is sufficiently strong, the entanglement grows at most
logarithmically in the number of spins. The proof utilises a transformation to
a model of classical probability called the continuum random-cluster model, and
is based on a property of the latter model termed ratio weak-mixing. Our proof
applies equally to a large class of disordered interactions.


title: Methanol masers as tools to study high-mass star formation

abstract:
  In this contribution I will attempt to show that the study of galactic 6.7
and 12.2GHz methanol masers themselves, as opposed to the use of methanol
masers as signposts, can yield important conclusions contributing to the
understanding of high-mass star formation. Due to their exclusive association
with star formation, methanol masers are the best tools to do this, and their
large number allows to probe the entire Galaxy. In particular I will focus on
the determination of the luminosity function of methanol masers and on the
determination of an unambiguous signature for a circumstellar masing disc seen
edge-on. Finally I will try to point out some future fields of research in the
study of methanol masers.


title:
Prospects for Stochastic Background Searches Using Virgo and LSC
  Interferometers

abstract:
  We consider the question of cross-correlation measurements using Virgo and
the LSC Interferometers (LIGO Livingston, LIGO Hanford, and GEO600) to search
for a stochastic gravitational-wave background. We find that inclusion of Virgo
into the network will substantially improve the sensitivity to correlations
above 200 Hz if all detectors are operating at their design sensitivity. This
is illustrated using a simulated isotropic stochastic background signal,
generated with an astrophysically-motivated spectrum, injected into 24 hours of
simulated noise for the LIGO and Virgo interferometers.


title: Globally stable quasistatic evolution in plasticity with softening

abstract:
  We study a relaxed formulation of the quasistatic evolution problem in the
context of small strain associative elastoplasticity with softening. The
relaxation takes place in spaces of generalized Young measures. The notion of
solution is characterized by the following properties: global stability at each
time and energy balance on each time interval. An example developed in detail
compares the solutions obtained by this method with the ones provided by a
vanishing viscosity approximation, and shows that only the latter capture a
decreasing branch in the stress-strain response.


title: Electronic structure of BaFeO3: an abinitio DFT study

abstract:
  First principles calculations were performed to study the ground state
electronic properties of BaFeO3 (BFO) within the density functional theory
(DFT). Adopting generalized gradient approximation (GGA) exchange and
correlation functional and Vosko-Wilk-Nusair correlation energy functional
interpolation, we have systematically conducted the band structure, density of
states and electronic distribution along different crystalline planes.
Calculating results show that band gap in the majority spin band structure and
band gap in the minority spin band structure were found to be 2.7012 eV and
0.6867 eV respectively. Up-spin Fe t2g were fully occupied and down-spin Fe eg
were empty. Moreover, the up-spin Fe eg and down-spin Fe t2g were partially
occupied near the Fermi energy, leading to a finite density of states. The
Fe4+-O-Fe4+ plane superexchange coupling should rearrange the magnetic order to
make the ferromagnetic characteristic being possible, moreover the tetragonal
displacement along the c axis could induce the perovskites materials to acquire
ferroelectric property. These reasons could lead to the fact that the
tetragonal phase BFO could be a potential multiferroics while it was produced
under the very experimental conditions. The charge density along different
crystalline planes were illustrated to show that strong covalent bonding
between O and Fe can be used to investigate the exchange coupling, and this
strong hybridization may further increase the superexchange coupling to enhance
the magnetic ordering.


title: States of Low Energy on Robertson-Walker Spacetimes

abstract:
  We construct a new class of physical states of the free Klein-Gordon field in
Robertson-Walker spacetimes. This is done by minimizing the expectation value
of smeared stress-energy. We get an explicit expression for the state depending
on the smearing function. We call it a state of low energy. States of low
energy are an improvement of the concept of adiabatic vacua on Robertson-Walker
spacetimes. The latter are approximations of the former. It is shown that
states of low energy are Hadamard states.


title: How tight is the Lieb-Oxford bound?

abstract:
  Density-functional theory requires ever better exchange-correlation (xc)
functionals for the ever more precise description of many-body effects on
electronic structure. Universal constraints on the xc energy are important
ingredients in the construction of improved functionals. Here we investigate
one such universal property of xc functionals: the Lieb-Oxford lower bound on
the exchange-correlation energy, $E_{xc}[n] \ge -C \int d^3r n^{4/3}$, where
$C\leq C_{LO}=1.68$. To this end, we perform a survey of available exact or
near-exact data on xc energies of atoms, ions, molecules, solids, and some
model Hamiltonians (the electron liquid, Hooke's atom and the Hubbard model).
All physically realistic density distributions investigated are consistent with
the tighter limit $C \leq 1$. For large classes of systems one can obtain
class-specific (but not fully universal) similar bounds. The Lieb-Oxford bound
with $C_{LO}=1.68$ is a key ingredient in the construction of modern xc
functionals, and a substantial change in the prefactor $C$ will have
consequences for the performance of these functionals.


title: On solving systems of random linear disequations

abstract:
  An important subcase of the hidden subgroup problem is equivalent to the
shift problem over abelian groups. An efficient solution to the latter problem
would serve as a building block of quantum hidden subgroup algorithms over
solvable groups. The main idea of a promising approach to the shift problem is
reduction to solving systems of certain random disequations in finite abelian
groups. The random disequations are actually generalizations of linear
functions distributed nearly uniformly over those not containing a specific
group element in the kernel. In this paper we give an algorithm which finds the
solutions of a system of N random linear disequations in an abelian p-group A
in time polynomial in N, where N=(log|A|)^{O(q)}, and q is the exponent of A.


title: On the geometric quantization of twisted Poisson manifolds

abstract:
  We study the geometric quantization process for twisted Poisson manifolds.
First, we introduce the notion of Lichnerowicz-twisted Poisson cohomology for
twisted Poisson manifolds and we use it in order to characterize their
prequantization bundles and to establish their prequantization condition. Next,
we introduce a polarization and we discuss the quantization problem. In each
step, several examples are presented.


title:
The principle of a virtual multi-channel lock-in amplifier and its
  application to magnetoelectric measurement system

abstract:
  This letter presents principles and applications of a virtual multi-channel
lock-in amplifier that is a simple but effective method to recover small ac
signal from noise with high presison. The fundamentals of this method are based
on calculation of cross-correlation function. Via this method, we successfully
built up a magnetoelectric measurement system which can perform precise and
versatile measurements without any analog lock-in amplifier. Using the virtual
multi-channel lock-in amplifier, the output of the magnetoelectric measurement
system is extensively rich in magnetoelectric coupling behaviors, including
coupling strength and phase lag, under various dc bias magnetic field and ac
magnetic field.


title: Second post-Newtonian approximation of scalar-tensor theory of gravity

abstract:
  Deep space laser ranging missions like ASTROD I (Single-Spacecraft
Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD,
together with astrometry missions like GAIA and LATOR will be able to test
relativistic gravity to an unprecedented level of accuracy. More precisely,
these missions will enable us to test relativistic gravity to
$10^{-7}-10^{-9}$, and will require 2nd post-Newtonian approximation of
relevant theories of gravity. The first post-Newtonian approximation is valid
to $10^{-6}$ and the second post-Newtonian is valid to $10^{-12}$ in the solar
system. The scalar-tensor theory is widely discussed and used in tests of
relativistic gravity, especially after the interests in inflation, cosmological
constant and dark energy in cosmology. In the Lagrangian, intermediate-range
gravity term has a similar form as cosmological term. Here we present the full
second post-Newtonian approximation of the scalar-tensor theory including
viable examples of intermediate-range gravity. We use Chandrasekhar's approach
to derive the metric coefficients and the equation of the hydrodynamics
governing a perfect fluid in the 2nd post-Newtonian approximation in
scalar-tensor theory; all terms inclusive of $O(c^{-4})$ are retained
consistently in the equation of motion.


title: Fluctuation theorems and orbital magnetism in nonequilibrium state

abstract:
  We study Langevin dynamics of a driven charged particle in the presence as
well as in the absence of magnetic field. We discuss the validity of various
work fluctuation theorems using different model potentials and external drives.
We also show that one can generate an orbital magnetic moment in a
nonequilibrium state which is absent in equilibrium.


title: A large scale extinction map of the Galactic Anticenter from 2MASS

abstract:
  We present a 127deg x 63deg extinction map of the Anticenter of the Galaxy,
based on <J-H> and <H-K> colour excess maps from 2MASS. This 8001 square degree
map with a resolution of 4 arcminutes is provided as online material. The
colour excess ratio <J-H> / <H-K> is used to determine the power law index of
the reddening law (\beta) for individual regions contained in the area (e.g.
Orion, Perseus, Taurus, Auriga, Monoceros, Camelopardalis, Cassiopeia). On
average we find a dominant value of \beta=1.8+-0.2 for the individual clouds,
in agreement with the canonical value for the interstellar medium. We also show
that there is an internal scatter of \beta values in these regions, and that in
some areas more than one dominant \beta value is present. This indicates large
scale variations in the dust properties. The analysis of the A_V values within
individual regions shows a change in the slope of the column density
distribution with distance. This can either be attributed to a change in the
governing physical processes in molecular clouds on spatial scales of about 1pc
or an A_V dilution with distance in our map.


title: Spontaneous Lorentz Violation, Gravity, and Nambu-Goldstone Modes

abstract:
  A brief summary is presented of recent work examining the fate of the
Nambu-Goldstone modes in gravitational theories with spontaneous Lorentz
violation.


title: Finite determination of regular (a,b)-modules

abstract:
  The concept of (a,b)-module comes from the study the Gauss-Manin lattices of
an isolated singularity of a germ of an holomorphic function. It is a very
simple ''abstract algebraic structure'', but very rich, whose prototype is the
formal completion of the Brieskorn-module of an isolated singularity. The aim
of this article is to prove a very basic theorem on regular (a,b)-modules
showing that a given regular (a,b)-module is completely characterized by some
''finite order jet'' of its structure. Moreover a very simple bound for such a
sufficient order is given in term of the rank and of two very simple invariants
: the regularity order which count the number of times you need to apply \
$b^{-1}.a \simeq \partial_z.z$ in order to reach a simple pole (a,b)-module.
The second invariant is the ''width'' which corresponds, in the simple pole
case, to the maximal integral difference between to eigenvalues of $b^{-1}.a$
  (the logarithm of the monodromy). In the computation of examples this theorem
is quite helpfull because it tells you at which power of $b$ in the expansions
you may stop without loosing any information.


title:
Low regularity local well-posedness of the Derivative Nonlinear
  Schr\"odinger Equation with periodic initial data

abstract:
  The Cauchy problem for the derivative nonlinear Schr\"odinger equation with
periodic boundary condition is considered. Local well-posedness for periodic
initial data u_0 in the space ^H^s_r, defined by the norms
||u_0||_{^H^s_r}=||<xi>^s ^u_0||_{l^r'} is shown in the parameter range s>=
1/2, 2>r>4/3. The proof is based on an adaptation of the gauge transform to the
periodic setting and an appropriate variant of the Fourier restriction norm
method.


title:
A Possible Stellar Metallic Enhancement in Post-T Tauri Stars by a
  Planetesimal Bombardment

abstract:
  The photospheres of stars hosting planets have larger metallicity than stars
lacking planets. In the present work we study the possibility of an earlier
metal enrichment of the photospheres by means of impacting planetesimals during
the first 20-30Myr. Here we explore this contamination process by simulating
the interactions of an inward migrating planet with a disc of planetesimal
interior to its orbit. The results show the percentage of planetesimals that
fall on the star. We identified the dependence of the planet's eccentricity
($e_p$) and time scale of migration ($\tau$) on the rate of infalling
planetesimals. For very fast migrations ($\tau=10^2$yr and $\tau=10^3$yr) there
is no capture in mean motion resonances, independently of the value of $e_p$.
Then, due to the planet's migration the planetesimals suffer close approaches
with the planet and more than 80% of them are ejected from the system. For slow
migrations ($\tau=10^5$yr and $\tau=10^6$yr) the percentage of collisions with
the planet decrease with the increase of the planet's eccentricity. For $e_p=0$
and $e_p=0.1$ most of the planetesimals were captured in the 2:1 resonance and
more than 65% of them collided with the star. Whereas migration of a Jupiter
mass planet to very short pericentric distances requires unrealistic high disc
masses, these requirements are much smaller for smaller migrating planets. Our
simulations for a slowly migrating 0.1 $M_{\rm Jupiter}$ planet, even demanding
a possible primitive disc three times more massive than a primitive solar
nebula, produces maximum [Fe/H] enrichments of the order of 0.18 dex. These
calculations open possibilities to explain hot Jupiters exoplanets
metallicities.


title:
Reconciliation of Zero-Point and Dark Energies in a Friedman Dust
  Universe with Einstein's Lambda

abstract:
  In this paper, it is shown that the cosmological model that was introduced in
a sequence of three earlier papers under the title, A Dust Universe Solution to
the Dark Energy Problem, can be used to resolve the problem of the great
mismatch of numerical values between dark energy from cosmology and zero point
energy from quantum theory. It is shown that, if the zero point energies for
the cosmic microwave background and for all the rest of the universe that is
not cosmic microwave background are introduced into this model as two entities,
their separate values appear within this theory in the form of a numerical
difference. It is this difference that gives the numerical value for the zero
point value of Einstein's dark energy density. Consequently, although the two
zero point energies may be large, their difference can give the known small
dark energy value from cosmology for dark energy density. Issues relating to
interpretation, calculation and measurement associated with this result and an
interpretation of dark energy as a measure of polarisation of the vacuum are
discussed. In the first appendix to this paper, problems associated with the
standard model of cosmology are solved by redefining temperature in the dust
universe model. In the second appendix of this paper, an examination of the
dark matter problem in relation to a general relativistic generalisation of
Newton's inverse square law is undertaken. In the third appendix to this paper,
the formalism is used to derive a formula that gives a possible value for the
mass of the universe in terms of Newton's gravitation constant, Einstein's
Lambda and the velocity of light. All three appendices have their own detailed
abstracts.


title: Accurate QCD predictions for heavy-quark jets at the Tevatron and LHC

abstract:
  Heavy-quark jets are important in many of today's collider studies and
searches, yet predictions for them are subject to much larger uncertainties
than for light jets. This is because of strong enhancements in higher orders
from large logarithms, ln(p_t/m_Q). We propose a new definition of heavy-quark
jets, which is free of final-state logarithms to all orders and such that all
initial-state collinear logarithms can be resummed into the heavy-quark parton
distributions. Heavy-jet spectra can then be calculated in the massless
approximation, which is simpler than a massive calculation and reduces the
theoretical uncertainties by a factor of three. This provides the first ever
accurate predictions for inclusive b- and c-jets, and the latter have
significant discriminatory power for the intrinsic charm content of the proton.
The techniques introduced here could be used to obtain heavy-flavour jet
results from existing massless next-to-leading order calculations for a wide
range of processes. We also discuss the experimental applicability of our
flavoured jet definition.


title: Exploiting the directional sensitivity of the Double Chooz near detector

abstract:
  In scintillator detectors, the forward displacement of the neutron in the
reaction $\bar\nu_e+p\to e^++n$ provides neutrino directional information as
demonstrated by the CHOOZ reactor experiment with 2,500 events. The near
detector of the forthcoming Double Chooz experiment will collect
$1.6\times10^5$ events per year, enough to determine the average neutrino
direction with a $1 \sigma$ half-cone aperture of $2.3^\circ$ in one year. It
is more difficult to separate the two Chooz reactors that are viewed at a
separation angle $\phi=30^\circ$. If their strengths are known and
approximately equal, the azimuthal location of each reactor is obtained with
$\pm6^\circ$ ($1 \sigma$) and the probability of confusing them with a single
source is less than 11%. Five year's data reduce this ``confusion probability''
to less than 0.3%, i.e., a $3 \sigma$ separation is possible. All of these
numbers improve rapidly with increasing angular separation of the sources. For
a setup with $\phi=90^\circ$ and one year's data, the azimuthal $1 \sigma$
uncertainty for each source decreases to $\pm3.2^\circ$. Of course, for Double
Chooz the two reactor locations are known, allowing one instead to measure
their individual one-year integrated power output to $\pm11%$ ($1 \sigma$), and
their five-year integrated output to $\pm4.8%$ ($1 \sigma$).


title:
Multidimensional supernova simulations with approximative neutrino
  transport. II. Convection and the advective-acoustic cycle in the supernova
  core

abstract:
  By 2D hydrodynamic simulations including a detailed equation of state and
neutrino transport, we investigate the interplay between different non-radial
hydrodynamic instabilities that play a role during the postbounce accretion
phase of collapsing stellar cores. The convective mode of instability, which is
driven by negative entropy gradients caused by neutrino heating or by time
variations of the shock strength, can be identified clearly by the development
of typical Rayleigh-Taylor mushrooms. However, in cases where the gas in the
postshock region is rapidly advected towards the gain radius, the growth of
such a buoyancy instability can be suppressed. In such a situation the shocked
flow nevertheless can develop non-radial asymmetry with an oscillatory growth
of the amplitude. This phenomenon has been termed ``standing accretion shock
instability'' (SASI). It is shown here that the SASI oscillations can trigger
convective instability and like the latter they lead to an increase of the
average shock radius and of the mass in the gain layer. Both hydrodynamic
instabilities in combination stretch the advection time of matter through the
neutrino-heating layer and thus enhance the neutrino energy deposition in
support of the neutrino-driven explosion mechanism. A rapidly contracting and
more compact nascent NS turns out to be favorable for explosions, because the
accretion luminosity and neutrino heating are larger and the growth rate of the
SASI is higher. Moreover, we show that the oscillation period of the SASI and a
variety of other features in our simulations agree with estimates for the
advective-acoustic cycle (AAC), in which perturbations are carried by the
accretion flow from the shock to the neutron star and pressure waves close an
amplifying global feedback loop. (abridged)


title: On the inverse braid monoid

abstract:
  Inverse braid monoid describes a structure on braids where the number of
strings is not fixed. So, some strings of initial $n$ may be deleted. In the
paper we show that many properties and objects based on braid groups may be
extended to the inverse braid monoids. Namely we prove an inclusion into a
monoid of partial monomorphisms of a free group. This gives a solution of the
word problem. Another solution is obtained by an approach similar to that of
Garside. We give also the analogues of Artin presentation with two generators
and Sergiescu graph-presentations.


title: Deformation principle and further geometrization of physics

abstract:
  The space-time geometry is considered to be a physical geometry, i.e. a
geometry described completely by the world function. All geometrical concepts
and geometric objects are taken from the proper Euclidean geometry. They are
expressed via the Euclidean world function \sigma_E and declared to be concepts
and objects of any physical geometry, provided the Euclidean world function
\sigma_E is replaced by the world function \sigma of the physical geometry in
question. The set of physical geometries is more powerful, than the set of
Riemannian geometries, and one needs to choose a true space-time geometry. In
general, the physical geometry is multivariant (there are many vectors which
are equivalent to a given vector, but are not equivalent between themselves).
The multivariance admits one to describe quantum effects as geometric effects
and to consider existence of elementary particles as a geometrical problem,
when the possibility of the physical existence of an elementary geometric
object in the form of a physical body is determined by the space-time geometry.
Multivariance admits one to describe discrete and continuous geometries, using
the same technique. A use of physical geometry admits one to realize the
geometrical approach to the quantum theory and to the theory of elementary
particles.


title: Four-Quark Condensates in Nucleon QCD Sum Rules

abstract:
  The in-medium behavior of the nucleon spectral density including
self-energies is revisited within the framework of QCD sum rules. Special
emphasis is given to the density dependence of four-quark condensates. A
complete catalog of four-quark condensates is presented and relations among
them are derived. Generic differences of such four-quark condensates occurring
in QCD sum rules for light baryons and light vector mesons are discussed.


title: A balanced memory network

abstract:
  A fundamental problem in neuroscience is understanding how working memory --
the ability to store information at intermediate timescales, like 10s of
seconds -- is implemented in realistic neuronal networks. The most likely
candidate mechanism is the attractor network, and a great deal of effort has
gone toward investigating it theoretically. Yet, despite almost a quarter
century of intense work, attractor networks are not fully understood. In
particular, there are still two unanswered questions. First, how is it that
attractor networks exhibit irregular firing, as is observed experimentally
during working memory tasks? And second, how many memories can be stored under
biologically realistic conditions? Here we answer both questions by studying an
attractor neural network in which inhibition and excitation balance each other.
Using mean field analysis, we derive a three-variable description of attractor
networks. From this description it follows that irregular firing can exist only
if the number of neurons involved in a memory is large. The same mean field
analysis also shows that the number of memories that can be stored in a network
scales with the number of excitatory connections, a result that has been
suggested for simple models but never shown for realistic ones. Both of these
predictions are verified using simulations with large networks of spiking
neurons.


title: On the Equilibrium Fluctuations of an Isolated System

abstract:
  Traditionally, it is understood that fluctuations in the equilibrium
distribution are not evident in thermodynamic systems of large $N$ (the number
of particles in the system) \cite{Huang1}. In this paper we examine the
validity of this perception by investigating whether such fluctuations can in
reality depend on temperature.
  Firstly, we describe fluctuations in the occupation numbers of the energy
levels for an isolated system, using previously unknown identities that we have
derived for the purpose, which allow us to calculate the moments of the
occupation numbers. Then we compute analytically the probability distribution
of these fluctuations. We show that, for every system of fixed and finite $N$,
fluctuations about the equilibrium distribution do, in fact, depend on the
temperature. Indeed, at higher temperatures the fluctuations can be so large
that the system does not fully converge on the Maxwell-Boltzmann distribution
but actually fluctuates around it. We term this state, where not one macrostate
but a region of macrostates closely fit the underlying distribution, a ``{\it
fluctuating equilibrium}''. Finally, we speculate on how this finding is
applicable to networks, financial markets, and other thermodynamic-like
systems.