title: Probability Update: Conditioning vs. Cross-Entropy

abstract:
  Conditioning is the generally agreed-upon method for updating probability
distributions when one learns that an event is certainly true. But it has been
argued that we need other rules, in particular the rule of cross-entropy
minimization, to handle updates that involve uncertain information. In this
paper we re-examine such a case: van Fraassen's Judy Benjamin problem, which in
essence asks how one might update given the value of a conditional probability.
We argue that -- contrary to the suggestions in the literature -- it is
possible to use simple conditionalization in this case, and thereby obtain
answers that agree fully with intuition. This contrasts with proposals such as
cross-entropy, which are easier to apply but can give unsatisfactory answers.
Based on the lessons from this example, we speculate on some general
philosophical issues concerning probability update.


title:
Problem-Focused Incremental Elicitation of Multi-Attribute Utility
  Models

abstract:
  Decision theory has become widely accepted in the AI community as a useful
framework for planning and decision making. Applying the framework typically
requires elicitation of some form of probability and utility information. While
much work in AI has focused on providing representations and tools for
elicitation of probabilities, relatively little work has addressed the
elicitation of utility models. This imbalance is not particularly justified
considering that probability models are relatively stable across problem
instances, while utility models may be different for each instance. Spending
large amounts of time on elicitation can be undesirable for interactive systems
used in low-stakes decision making and in time-critical decision making. In
this paper we investigate the issues of reasoning with incomplete utility
models. We identify patterns of problem instances where plans can be proved to
be suboptimal if the (unknown) utility function satisfies certain conditions.
We present an approach to planning and decision making that performs the
utility elicitation incrementally and in a way that is informed by the domain
model.


title: Models and Selection Criteria for Regression and Classification

abstract:
  When performing regression or classification, we are interested in the
conditional probability distribution for an outcome or class variable Y given a
set of explanatoryor input variables X. We consider Bayesian models for this
task. In particular, we examine a special class of models, which we call
Bayesian regression/classification (BRC) models, that can be factored into
independent conditional (y|x) and input (x) models. These models are
convenient, because the conditional model (the portion of the full model that
we care about) can be analyzed by itself. We examine the practice of
transforming arbitrary Bayesian models to BRC models, and argue that this
practice is often inappropriate because it ignores prior knowledge that may be
important for learning. In addition, we examine Bayesian methods for learning
models from data. We discuss two criteria for Bayesian model selection that are
appropriate for repression/classification: one described by Spiegelhalter et
al. (1993), and another by Buntine (1993). We contrast these two criteria using
the prequential framework of Dawid (1984), and give sufficient conditions under
which the criteria agree.


title: Inference with Idempotent Valuations

abstract:
  Valuation based systems verifying an idempotent property are studied. A
partial order is defined between the valuations giving them a lattice
structure. Then, two different strategies are introduced to represent
valuations: as infimum of the most informative valuations or as supremum of the
least informative ones. It is studied how to carry out computations with both
representations in an efficient way. The particular cases of finite sets and
convex polytopes are considered.


title:
Perception, Attention, and Resources: A Decision-Theoretic Approach to
  Graphics Rendering

abstract:
  We describe work to control graphics rendering under limited computational
resources by taking a decision-theoretic perspective on perceptual costs and
computational savings of approximations. The work extends earlier work on the
control of rendering by introducing methods and models for computing the
expected cost associated with degradations of scene components. The expected
cost is computed by considering the perceptual cost of degradations and a
probability distribution over the attentional focus of viewers. We review the
critical literature describing findings on visual search and attention, discuss
the implications of the findings, and introduce models of expected perceptual
cost. Finally, we discuss policies that harness information about the expected
cost of scene components.


title: Time-Critical Reasoning: Representations and Application

abstract:
  We review the problem of time-critical action and discuss a reformulation
that shifts knowledge acquisition from the assessment of complex temporal
probabilistic dependencies to the direct assessment of time-dependent utilities
over key outcomes of interest. We dwell on a class of decision problems
characterized by the centrality of diagnosing and reacting in a timely manner
to pathological processes. We motivate key ideas in the context of trauma-care
triage and transportation decisions.


title:
Learning Belief Networks in Domains with Recursively Embedded Pseudo
  Independent Submodels

abstract:
  A pseudo independent (PI) model is a probabilistic domain model (PDM) where
proper subsets of a set of collectively dependent variables display marginal
independence. PI models cannot be learned correctly by many algorithms that
rely on a single link search. Earlier work on learning PI models has suggested
a straightforward multi-link search algorithm. However, when a domain contains
recursively embedded PI submodels, it may escape the detection of such an
algorithm. In this paper, we propose an improved algorithm that ensures the
learning of all embedded PI submodels whose sizes are upper bounded by a
predetermined parameter. We show that this improved learning capability only
increases the complexity slightly beyond that of the previous algorithm. The
performance of the new algorithm is demonstrated through experiment.


title: Relational Bayesian Networks

abstract:
  A new method is developed to represent probabilistic relations on multiple
random events. Where previously knowledge bases containing probabilistic rules
were used for this purpose, here a probability distribution over the relations
is directly represented by a Bayesian network. By using a powerful way of
specifying conditional probability distributions in these networks, the
resulting formalism is more expressive than the previous ones. Particularly, it
provides for constraints on equalities of events, and it allows to define
complex, nested combination functions.


title: Composition of Probability Measures on Finite Spaces

abstract:
  Decomposable models and Bayesian networks can be defined as sequences of
oligo-dimensional probability measures connected with operators of composition.
The preliminary results suggest that the probabilistic models allowing for
effective computational procedures are represented by sequences possessing a
special property; we shall call them perfect sequences. The paper lays down the
elementary foundation necessary for further study of iterative application of
operators of composition. We believe to develop a technique describing several
graph models in a unifying way. We are convinced that practically all
theoretical results and procedures connected with decomposable models and
Bayesian networks can be translated into the terminology introduced in this
paper. For example, complexity of computational procedures in these models is
closely dependent on possibility to change the ordering of oligo-dimensional
measures defining the model. Therefore, in this paper, lot of attention is paid
to possibility to change ordering of the operators of composition.


title:
An Information-Theoretic Analysis of Hard and Soft Assignment Methods
  for Clustering

abstract:
  Assignment methods are at the heart of many algorithms for unsupervised
learning and clustering - in particular, the well-known K-means and
Expectation-Maximization (EM) algorithms. In this work, we study several
different methods of assignment, including the "hard" assignments used by
K-means and the ?soft' assignments used by EM. While it is known that K-means
minimizes the distortion on the data and EM maximizes the likelihood, little is
known about the systematic differences of behavior between the two algorithms.
Here we shed light on these differences via an information-theoretic analysis.
The cornerstone of our results is a simple decomposition of the expected
distortion, showing that K-means (and its extension for inferring general
parametric densities from unlabeled sample data) must implicitly manage a
trade-off between how similar the data assigned to each cluster are, and how
the data are balanced among the clusters. How well the data are balanced is
measured by the entropy of the partition defined by the hard assignments. In
addition to letting us predict and verify systematic differences between
K-means and EM on specific examples, the decomposition allows us to give a
rather general argument showing that K ?means will consistently find densities
with less "overlap" than EM. We also study a third natural assignment method
that we call posterior assignment, that is close in spirit to the soft
assignments of EM, but leads to a surprisingly different algorithm.


title: Nested Junction Trees

abstract:
  The efficiency of inference in both the Hugin and, most notably, the
Shafer-Shenoy architectures can be improved by exploiting the independence
relations induced by the incoming messages of a clique. That is, the message to
be sent from a clique can be computed via a factorization of the clique
potential in the form of a junction tree. In this paper we show that by
exploiting such nested junction trees in the computation of messages both space
and time costs of the conventional propagation methods may be reduced. The
paper presents a structured way of exploiting the nested junction trees
technique to achieve such reductions. The usefulness of the method is
emphasized through a thorough empirical evaluation involving ten large
real-world Bayesian networks and the Hugin inference algorithm.


title: Object-Oriented Bayesian Networks

abstract:
  Bayesian networks provide a modeling language and associated inference
algorithm for stochastic domains. They have been successfully applied in a
variety of medium-scale applications. However, when faced with a large complex
domain, the task of modeling using Bayesian networks begins to resemble the
task of programming using logical circuits. In this paper, we describe an
object-oriented Bayesian network (OOBN) language, which allows complex domains
to be described in terms of inter-related objects. We use a Bayesian network
fragment to describe the probabilistic relations between the attributes of an
object. These attributes can themselves be objects, providing a natural
framework for encoding part-of hierarchies. Classes are used to provide a
reusable probabilistic model which can be applied to multiple similar objects.
Classes also support inheritance of model fragments from a class to a subclass,
allowing the common aspects of related classes to be defined only once. Our
language has clear declarative semantics: an OOBN can be interpreted as a
stochastic functional program, so that it uniquely specifies a probabilistic
model. We provide an inference algorithm for OOBNs, and show that much of the
structural information encoded by an OOBN--particularly the encapsulation of
variables within an object and the reuse of model fragments in different
contexts--can also be used to speed up the inference process.


title: Nonuniform Dynamic Discretization in Hybrid Networks

abstract:
  We consider probabilistic inference in general hybrid networks, which include
continuous and discrete variables in an arbitrary topology. We reexamine the
question of variable discretization in a hybrid network aiming at minimizing
the information loss induced by the discretization. We show that a nonuniform
partition across all variables as opposed to uniform partition of each variable
separately reduces the size of the data structures needed to represent a
continuous function. We also provide a simple but efficient procedure for
nonuniform partition. To represent a nonuniform discretization in the computer
memory, we introduce a new data structure, which we call a Binary Split
Partition (BSP) tree. We show that BSP trees can be an exponential factor
smaller than the data structures in the standard uniform discretization in
multiple dimensions and show how the BSP trees can be used in the standard join
tree algorithm. We show that the accuracy of the inference process can be
significantly improved by adjusting discretization with evidence. We construct
an iterative anytime algorithm that gradually improves the quality of the
discretization and the accuracy of the answer on a query. We provide empirical
evidence that the algorithm converges.


title: Probabilistic Acceptance

abstract:
  The idea of fully accepting statements when the evidence has rendered them
probable enough faces a number of difficulties. We leave the interpretation of
probability largely open, but attempt to suggest a contextual approach to full
belief. We show that the difficulties of probabilistic acceptance are not as
severe as they are sometimes painted, and that though there are oddities
associated with probabilistic acceptance they are in some instances less
awkward than the difficulties associated with other nonmonotonic formalisms. We
show that the structure at which we arrive provides a natural home for
statistical inference.


title:
Network Fragments: Representing Knowledge for Constructing Probabilistic
  Models

abstract:
  In most current applications of belief networks, domain knowledge is
represented by a single belief network that applies to all problem instances in
the domain. In more complex domains, problem-specific models must be
constructed from a knowledge base encoding probabilistic relationships in the
domain. Most work in knowledge-based model construction takes the rule as the
basic unit of knowledge. We present a knowledge representation framework that
permits the knowledge base designer to specify knowledge in larger semantically
meaningful units which we call network fragments. Our framework provides for
representation of asymmetric independence and canonical intercausal
interaction. We discuss the combination of network fragments to form
problem-specific models to reason about particular problem instances. The
framework is illustrated using examples from the domain of military situation
awareness.


title:
Computational Advantages of Relevance Reasoning in Bayesian Belief
  Networks

abstract:
  This paper introduces a computational framework for reasoning in Bayesian
belief networks that derives significant advantages from focused inference and
relevance reasoning. This framework is based on d -separation and other simple
and computationally efficient techniques for pruning irrelevant parts of a
network. Our main contribution is a technique that we call relevance-based
decomposition. Relevance-based decomposition approaches belief updating in
large networks by focusing on their parts and decomposing them into partially
overlapping subnetworks. This makes reasoning in some intractable networks
possible and, in addition, often results in significant speedup, as the total
time taken to update all subnetworks is in practice often considerably less
than the time taken to update the network as a whole. We report results of
empirical tests that demonstrate practical significance of our approach.


title:
Incremental Map Generation by Low Cost Robots Based on
  Possibility/Necessity Grids

abstract:
  In this paper we present some results obtained with a troupe of low-cost
robots designed to cooperatively explore and adquire the map of unknown
structured orthogonal environments. In order to improve the covering of the
explored zone, the robots show different behaviours and cooperate by
transferring each other the perceived environment when they meet. The returning
robots deliver to a host computer their partial maps and the host incrementally
generates the map of the environment by means of apossibility/ necessity grid.


title: A Target Classification Decision Aid

abstract:
  A submarine's sonar team is responsible for detecting, localising and
classifying targets using information provided by the platform's sensor suite.
The information used to make these assessments is typically uncertain and/or
incomplete and is likely to require a measure of confidence in its reliability.
Moreover, improvements in sensor and communication technology are resulting in
increased amounts of on-platform and off-platform information available for
evaluation. This proliferation of imprecise information increases the risk of
overwhelming the operator. To assist the task of localisation and
classification a concept demonstration decision aid (Horizon), based on
evidential reasoning, has been developed. Horizon is an information fusion
software package for representing and fusing imprecise information about the
state of the world, expressed across suitable frames of reference. The Horizon
software is currently at prototype stage.


title:
Structure and Parameter Learning for Causal Independence and Causal
  Interaction Models

abstract:
  This paper discusses causal independence models and a generalization of these
models called causal interaction models. Causal interaction models are models
that have independent mechanisms where a mechanism can have several causes. In
addition to introducing several particular types of causal interaction models,
we show how we can apply the Bayesian approach to learning causal interaction
models obtaining approximate posterior distributions for the models and obtain
MAP and ML estimates for the parameters. We illustrate the approach with a
simulation study of learning model posteriors.


title: Support and Plausibility Degrees in Generalized Functional Models

abstract:
  By discussing several examples, the theory of generalized functional models
is shown to be very natural for modeling some situations of reasoning under
uncertainty. A generalized functional model is a pair (f, P) where f is a
function describing the interactions between a parameter variable, an
observation variable and a random source, and P is a probability distribution
for the random source. Unlike traditional functional models, generalized
functional models do not require that there is only one value of the parameter
variable that is compatible with an observation and a realization of the random
source. As a consequence, the results of the analysis of a generalized
functional model are not expressed in terms of probability distributions but
rather by support and plausibility functions. The analysis of a generalized
functional model is very logical and is inspired from ideas already put forward
by R.A. Fisher in his theory of fiducial probability.


title: The Cognitive Processing of Causal Knowledge

abstract:
  There is a brief description of the probabilistic causal graph model for
representing, reasoning with, and learning causal structure using Bayesian
networks. It is then argued that this model is closely related to how humans
reason with and learn causal structure. It is shown that studies in psychology
on discounting (reasoning concerning how the presence of one cause of an effect
makes another cause less probable) support the hypothesis that humans reach the
same judgments as algorithms for doing inference in Bayesian networks. Next, it
is shown how studies by Piaget indicate that humans learn causal structure by
observing the same independencies and dependencies as those used by certain
algorithms for learning the structure of a Bayesian network. Based on this
indication, a subjective definition of causality is forwarded. Finally, methods
for further testing the accuracy of these claims are discussed.


title:
Representing Aggregate Belief through the Competitive Equilibrium of a
  Securities Market

abstract:
  We consider the problem of belief aggregation: given a group of individual
agents with probabilistic beliefs over a set of uncertain events, formulate a
sensible consensus or aggregate probability distribution over these events.
Researchers have proposed many aggregation methods, although on the question of
which is best the general consensus is that there is no consensus. We develop a
market-based approach to this problem, where agents bet on uncertain events by
buying or selling securities contingent on their outcomes. Each agent acts in
the market so as to maximize expected utility at given securities prices,
limited in its activity only by its own risk aversion. The equilibrium prices
of goods in this market represent aggregate beliefs. For agents with constant
risk aversion, we demonstrate that the aggregate probability exhibits several
desirable properties, and is related to independently motivated techniques. We
argue that the market-based approach provides a plausible mechanism for belief
aggregation in multiagent systems, as it directly addresses self-motivated
agent incentives for participation and for truthfulness, and can provide a
decision-theoretic foundation for the "expert weights" often employed in
centralized pooling techniques.


title: Learning Bayesian Networks from Incomplete Databases

abstract:
  Bayesian approaches to learn the graphical structure of Bayesian Belief
Networks (BBNs) from databases share the assumption that the database is
complete, that is, no entry is reported as unknown. Attempts to relax this
assumption involve the use of expensive iterative methods to discriminate among
different structures. This paper introduces a deterministic method to learn the
graphical structure of a BBN from a possibly incomplete database. Experimental
evaluations show a significant robustness of this method and a remarkable
independence of its execution time from the number of missing data.


title:
Estimation of Effects of Sequential Treatments by Reparameterizing
  Directed Acyclic Graphs

abstract:
  The standard way to parameterize the distributions represented by a directed
acyclic graph is to insert a parametric family for the conditional distribution
of each random variable given its parents. We show that when one's goal is to
test for or estimate an effect of a sequentially applied treatment, this
natural parameterization has serious deficiencies. By reparameterizing the
graph using structural nested models, these deficiencies can be avoided.


title: Cost-Sharing in Bayesian Knowledge Bases

abstract:
  Bayesian knowledge bases (BKBs) are a generalization of Bayes networks and
weighted proof graphs (WAODAGs), that allow cycles in the causal graph.
Reasoning in BKBs requires finding the most probable inferences consistent with
the evidence. The cost-sharing heuristic for finding least-cost explanations in
WAODAGs was presented and shown to be effective by Charniak and Husain.
However, the cycles in BKBs would make the definition of cost-sharing cyclic as
well, if applied directly to BKBs. By treating the defining equations of
cost-sharing as a system of equations, one can properly define an admissible
cost-sharing heuristic for BKBs. Empirical evaluation shows that cost-sharing
improves performance significantly when applied to BKBs.


title: Conditional Utility, Utility Independence, and Utility Networks

abstract:
  We introduce a new interpretation of two related notions - conditional
utility and utility independence. Unlike the traditional interpretation, the
new interpretation renders the notions the direct analogues of their
probabilistic counterparts. To capture these notions formally, we appeal to the
notion of utility distribution, introduced in previous paper. We show that
utility distributions, which have a structure that is identical to that of
probability distributions, can be viewed as a special case of an additive
multiattribute utility functions, and show how this special case permits us to
capture the novel senses of conditional utility and utility independence.
Finally, we present the notion of utility networks, which do for utilities what
Bayesian networks do for probabilities. Specifically, utility networks exploit
the new interpretation of conditional utility and utility independence to
compactly represent a utility distribution.


title: Sequential Thresholds: Context Sensitive Default Extensions

abstract:
  Default logic encounters some conceptual difficulties in representing common
sense reasoning tasks. We argue that we should not try to formulate modular
default rules that are presumed to work in all or most circumstances. We need
to take into account the importance of the context which is continuously
evolving during the reasoning process. Sequential thresholding is a
quantitative counterpart of default logic which makes explicit the role context
plays in the construction of a non-monotonic extension. We present a semantic
characterization of generic non-monotonic reasoning, as well as the
instantiations pertaining to default logic and sequential thresholding. This
provides a link between the two mechanisms as well as a way to integrate the
two that can be beneficial to both.


title: On Stable Multi-Agent Behavior in Face of Uncertainty

abstract:
  A stable joint plan should guarantee the achievement of a designer's goal in
a multi-agent environment, while ensuring that deviations from the prescribed
plan would be detected. We present a computational framework where stable joint
plans can be studied, as well as several basic results about the
representation, verification and synthesis of stable joint plans.


title:
Score and Information for Recursive Exponential Models with Incomplete
  Data

abstract:
  Recursive graphical models usually underlie the statistical modelling
concerning probabilistic expert systems based on Bayesian networks. This paper
defines a version of these models, denoted as recursive exponential models,
which have evolved by the desire to impose sophisticated domain knowledge onto
local fragments of a model. Besides the structural knowledge, as specified by a
given model, the statistical modelling may also include expert opinion about
the values of parameters in the model. It is shown how to translate imprecise
expert knowledge into approximately conjugate prior distributions. Based on
possibly incomplete data, the score and the observed information are derived
for these models. This accounts for both the traditional score and observed
information, derived as derivatives of the log-likelihood, and the posterior
score and observed information, derived as derivatives of the log-posterior
distribution. Throughout the paper the specialization into recursive graphical
models is accounted for by a simple example.


title:
Lexical Access for Speech Understanding using Minimum Message Length
  Encoding

abstract:
  The Lexical Access Problem consists of determining the intended sequence of
words corresponding to an input sequence of phonemes (basic speech sounds) that
come from a low-level phoneme recognizer. In this paper we present an
information-theoretic approach based on the Minimum Message Length Criterion
for solving the Lexical Access Problem. We model sentences using phoneme
realizations seen in training, and word and part-of-speech information obtained
from text corpora. We show results on multiple-speaker, continuous, read speech
and discuss a heuristic using equivalence classes of similar sounding words
which speeds up the recognition process without significant deterioration in
recognition accuracy.


title: Region-Based Approximations for Planning in Stochastic Domains

abstract:
  This paper is concerned with planning in stochastic domains by means of
partially observable Markov decision processes (POMDPs). POMDPs are difficult
to solve. This paper identifies a subclass of POMDPs called region observable
POMDPs, which are easier to solve and can be used to approximate general POMDPs
to arbitrary accuracy.


title: Independence of Causal Influence and Clique Tree Propagation

abstract:
  This paper explores the role of independence of causal influence (ICI) in
Bayesian network inference. ICI allows one to factorize a conditional
probability table into smaller pieces. We describe a method for exploiting the
factorization in clique tree propagation (CTP) - the state-of-the-art exact
inference algorithm for Bayesian networks. We also present empirical results
showing that the resulting algorithm is significantly more efficient than the
combination of CTP and previous techniques for exploiting ICI.


title: Fast Value Iteration for Goal-Directed Markov Decision Processes

abstract:
  Planning problems where effects of actions are non-deterministic can be
modeled as Markov decision processes. Planning problems are usually
goal-directed. This paper proposes several techniques for exploiting the
goal-directedness to accelerate value iteration, a standard algorithm for
solving Markov decision processes. Empirical studies have shown that the
techniques can bring about significant speedups.


title: What triggers black-hole growth? Insights from star formation rates

abstract:
  We present a new semi-analytic model for the common growth of black holes
(BHs) and galaxies within a hierarchical Universe. The model is tuned to match
the mass function of BHs at z=0 and the luminosity functions of active galactic
nuclei (AGNs) at z<4. We use a new observational constraint, which relates the
luminosity of AGNs to the star-formation rate (SFR) of their host galaxies. We
show that this new constraint is important in various aspects: a) it indicates
that BH accretion events are episodic; b) it favours a scenario in which BH
accretion is triggered by merger events of all mass ratios; c) it constrains
the duration of both merger-induced star-bursts and BH accretion events. The
model reproduces the observations once we assume that only 4 per cent of the
merger events trigger BH accretion; BHs accretion is not related to secular
evolution; and only a few per cent of the mass made in bursts goes into the BH.
We find that AGNs with low or intermediate luminosity are mostly being
triggered by minor merger events, in broad agreement with observations. Our
model matches various observed properties of galaxies, such as the stellar mass
function at z<4 and the clustering of galaxies at redshift zero. This allows us
to use galaxies as a reliable backbone for BH growth, with reasonable estimates
for the frequency of merger events. Other modes of BH accretion, such as
disk-instability events, were not considered here, and should be further
examined in the future.


title:
On the Theory of Continuous-Spin Particles: Helicity Correspondence in
  Radiation and Forces

abstract:
  We have recently shown that continuous-spin particles (CSPs) have covariant
single-emission amplitudes with the requisite properties to mediate long-range
forces. CSPs, the most general massless particle type consistent with Lorentz
symmetry, are characterized by a scale \rho. Here, we demonstrate a helicity
correspondence at CSP energies larger than \rho, in which these amplitudes are
well approximated by the familiar ones for particles of helicity 0, 1, or 2.
These properties follow from Lorentz invariance. We also construct tree-level
multi-emission and CSP-exchange amplitudes that are unitary, appropriately
analytic, and consistent with helicity-0 correspondence. We propose sewing
rules from which these amplitudes and others can be obtained. We also exhibit a
candidate CSP-graviton matrix element, which shows that the Weinberg-Witten
theorem does not apply to CSPs. These results raise the surprising possibility
that the known long-range forces might be mediated by CSPs with very small
\rho, rather than by helicity 1 and 2 particles.


title: On the origin of the clumpy streams of Palomar 5

abstract:
  In this paper we report a study (see Mastrobuono-Battisti et al., 2012) about
the formation and characteristics of the tidal tails around Palomar 5 along its
orbit in the Milky Way potential, by means of direct N-body simulations and
simplified numerical models. Unlike previous findings, we are able to reproduce
the substructures observed in the stellar streams of this cluster, without
including any lumpiness in the dark matter halo. We show that overdensities
similar to those observed in Palomar 5 can be reproduced by the epicyclic
motion of stars along its tails, i.e. a simple local accumulation of orbits of
stars that escaped from the cluster with very similar positions and velocities.
This process is able to form stellar clumps at distances of several kiloparsecs
from the cluster, so it is not a phenomenon confined to the inner part of
Palomar 5's tails, as previously suggested.


title: Laboratory search for a quintessence field

abstract:
  A cosmic scalar field evolving very slowly in time can account for the
observed dark energy of the Universe. Unlike a cosmological constant, an
evolving scalar field also has local spatial gradients due to gravity. If the
scalar field has a minimal derivative coupling to electromagnetism, it will
cause modifications of Maxwell's equations. In particular, in the presence of a
scalar field gradient generated by Earth's gravity, regions with a magnetic
field appear to be electrically charged and regions with a static electric
field appear to contain electric currents. We propose experiments to detect
such effects with sensitivity exceeding current limits on scalar field
interactions from measurements of cosmological birefringence. If the scalar
field has derivative couplings to fermions, it would also generate observable
effects in precision spin precession experiments.


title: Boundary Conditions for Kerr-AdS Perturbations

abstract:
  The Teukolsky master equation and its associated spin-weighted spheroidal
harmonic decomposition simplify considerably the study of linear gravitational
perturbations of the Kerr(-AdS) black hole. However, the formulation of the
problem is not complete before we assign the physically relevant boundary
conditions. We find a set of two Robin boundary conditions (BCs) that must be
imposed on the Teukolsky master variables to get perturbations that are
asymptotically global AdS, i.e. that asymptotes to the Einstein Static
Universe. In the context of the AdS/CFT correspondence, these BCs allow a
non-zero expectation value for the CFT stress-energy tensor while keeping fixed
the boundary metric. When the rotation vanishes, we also find the gauge
invariant differential map between the Teukolsky and the Kodama-Ishisbashi
(Regge-Wheeler-Zerilli) formalisms. One of our Robin BCs maps to the scalar
sector and the other to the vector sector of the Kodama-Ishisbashi
decomposition. The Robin BCs on the Teukolsky variables will allow for a
quantitative study of instability timescales and quasinormal mode spectrum of
the Kerr-AdS black hole. As a warm-up for this programme, we use the Teukolsky
formalism to recover the quasinormal mode spectrum of global AdS-Schwarzschild,
complementing previous analysis in the literature.


title:
The GALEX Time Domain Survey I. Selection and Classification of Over a
  Thousand UV Variable Sources

abstract:
  We present the selection and classification of over a thousand ultraviolet
(UV) variable sources discovered in ~ 40 deg^2 of GALEX Time Domain Survey
(TDS) NUV images observed with a cadence of 2 days and a baseline of
observations of ~ 3 years. The GALEX TDS fields were designed to be in spatial
and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which
provides deep optical imaging and simultaneous optical transient detections via
image differencing. We characterize the GALEX photometric errors empirically as
a function of mean magnitude, and select sources that vary at the 5\sigma level
in at least one epoch. We measure the statistical properties of the UV
variability, including the structure function on timescales of days and years.
We report classifications for the GALEX TDS sample using a combination of
optical host colors and morphology, UV light curve characteristics, and matches
to archival X-ray, and spectroscopy catalogs. We classify 62% of the sources as
active galaxies (358 quasars and 305 active galactic nuclei), and 10% as
variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2
cataclysmic variables). The remaining unclassified sources include UV-bright
extragalactic transients, two of which have been spectroscopically confirmed to
be a young core-collapse supernova and a flare from the tidal disruption of a
star by dormant supermassive black hole. We calculate a surface density for
variable sources in the UV with NUV < 23 mag and |\Delta m| > 0.2 mag of ~ 8.0,
7.7, and 1.8 deg^-2 for quasars, AGNs, and RR Lyrae stars, respectively. We
also calculate a surface density rate in the UV for transient sources, using
the effective survey time at the cadence appropriate to each class, of ~ 15 and
52 deg^-2 yr^-1 for M dwarfs and extragalactic transients, respectively.
(Abridged.)


title:
Evolution along the sequence of S0 Hubble types induced by dry minor
  mergers. II - Bulge-disk coupling in the photometric relations through
  merger-induced internal secular evolution

abstract:
  Galaxy mergers are considered as questionable mechanisms for the evolution of
lenticular galaxies (S0's), on the basis that even minor ones induce structural
changes that are difficult to reconcile with the strong bulge-disk coupling
observed in the photometric scaling relations of S0's. We check if the
evolution induced onto S0's by dry intermediate and minor mergers can reproduce
their photometric scaling relations, analysing the bulge-disk decompositions of
the merger simulations presented in Eliche-Moral et al. (2012). The mergers
induce an evolution in the photometric planes compatible with the data of S0's,
even in those ones indicating a strong bulge-disk coupling. The mergers drive
the formation of the observed photometric relation in some cases, whereas they
induce a slight dispersion compatible with data in others. Therefore, this
evolutionary mechanism tends to preserve these scaling relations. In those
photometric planes where the morphological types segregate, the mergers always
induce evolution towards the region populated by S0's. The structural coupling
of the bulge and the disk is preserved or reinforced because the mergers
trigger internal secular processes in the primary disk that induce significant
bulge growth, even although these models do not induce bars. Intermediate and
minor mergers can thus be considered as plausible mechanisms for the evolution
of S0's attending to their photometric scaling relations, as they can preserve
and even strengthen any pre-existing structural bulge-disk coupling, triggering
significant internal secular evolution (even in the absence of bars or
dissipational effects). This means that it may be difficult to isolate the
effects of pure internal secular evolution from those of the merger-driven one
in present-day early-type disks (abridged).


title: An Entropy Formula for Higher Spin Black Holes via Conical Singularities

abstract:
  We consider the entropy of higher spin black holes in 2+1 dimensions using
the conical singularity approach. By introducing a conical singularity along a
non contractible cycle and carefully evaluating its contribution to the Chern
Simons action, we derive a simple expression for the entropy of a general
stationary higher spin black hole. The resulting formula is shown to satisfy
the first law of thermodynamics, and yields agreement with previous results
based on integrating the first law.


title: Combining Size and Shape in Weak Lensing

abstract:
  Weak lensing alters the size of images with a similar magnitude to the
distortion due to shear. Galaxy size probes the convergence field, and shape
the shear field, both of which contain cosmological information. We show the
gains expected in the Dark Energy Figure of Merit if galaxy size information is
used in combination with galaxy shape. In any normal analysis of cosmic shear,
galaxy sizes are also studied, so this is extra statistical information comes
for free and is currently unused. There are two main results in this letter:
firstly, we show that size measurement can be made uncorrelated with
ellipticity measurement, thus allowing the full statistical gain from the
combination, provided that $\sqrt{Area}$ is used as a size indicator; secondly,
as a proof of concept, we show that when the relevant modes are
noise-dominated, as is the norm for lensing surveys, the gains are substantial,
with improvements of about 68% in the Figure of Merit expected when systematic
errors are ignored. An approximate treatment of such systematics such as
intrinsic alignments and size-magnitude correlations respectively suggests that
a much better improvement in the Dark Energy Figure of Merit of even a factor
of ~4 may be achieved.


title: Galaxy gas ejection in radio galaxies: the case of 3C 35

abstract:
  We report results from XMM-Newton and Chandra observations of the nearby (z =
0.067) giant radio galaxy 3C 35. We find evidence for an X-ray emitting gas
belt, orthogonal to and lying between the lobes of 3C 35, which we interpret as
fossil-group gas driven outwards by the expanding radio lobes. We also detect
weak emission from a second, more extended group-type environment, as well as
inverse-Compton X-ray emission from the radio lobes. The morphological
structure of the radio lobes and gas belt point to co-evolution. Furthermore,
the radio source is powerful enough to eject galaxy-scale gas out to distances
of 100kpc, and the ages of the two features are comparable (tsynch~140Myr,
tbelt~80 Myr). The destruction of 3C 35's atmosphere may offer clues as to how
fossil systems are regulated: radio galaxies need to be of power comparable to
3C 35 to displace and regulate fossil-group gas. We discuss the implications of
the gas belt in 3C 35 in terms of AGN fuelling and feedback.


title:
Feasibility of Determining Diffuse Ultra-High Energy Cosmic Neutrino
  Flavor Ratio through ARA Neutrino Observatory

abstract:
  The flavor composition of ultra-high energy cosmic neutrinos (UHECN) carries
precious information about the physical properties of their sources, the nature
of neutrino oscillations and possible exotic physics involved during the
propagation. Since UHECN with different incoming directions would propagate
through different amounts of matter in Earth and since different flavors of
charged leptons produced in the neutrino-nucleon charged-current (CC)
interaction would have different energy-loss behaviors in the medium,
measurement of the angular distribution of incoming events by a neutrino
observatory can in principle be employed to help determine the UHECN flavor
ratio. In this paper we report on our investigation of the feasibility of such
an attempt. Simulations were performed, where the detector configuration was
based on the proposed Askaryan Radio Array (ARA) Observatory at the South Pole,
to investigate the expected event-direction distribution for each flavor.
Assuming $\nu_{\mu}$-$\nu_{\tau}$ symmetry and invoking the standard
oscillation and the neutrino decay scenarios, the probability distribution
functions (PDF) of the event directions are utilized to extract the flavor
ratio of cosmogenic neutrinos on Earth. The simulation results are summarized
in terms of the probability of flavor ratio extraction and resolution as
functions of the number of observed events and the angular resolution of
neutrino directions. We show that it is feasible to constrain the UHECN flavor
ratio using the proposed ARA Observatory.


title:
Redshift 6.4 host galaxies of 10^8 solar mass black holes: low star
  formation rate and dynamical mass

abstract:
  We present ALMA observations of rest-frame far-infrared continuum and [CII]
line emission in two z=6.4 quasars with black hole masses of ~10^8 M_sun. CFHQS
J0210-0456 is detected in the continuum with a 1.2 mm flux of 120+/-35 microJy,
whereas CFHQS J2329-0301 is undetected at a similar noise level. J2329-0301 has
a star formation rate limit of <40 M_sun/yr, considerably below the typical
value at all redshifts for this bolometric luminosity. By comparison with hydro
simulations, we speculate that this quasar is observed at a relatively rare
phase where quasar feedback has effectively shut down star formation in the
host galaxy. [CII] emission is also detected only in J0210-0456. The ratio of
[CII] to far-infrared luminosity is similar to that of low redshift galaxies of
comparable luminosity, suggesting the previous finding of an offset in the
relationships between this ratio and far-infrared luminosity at low- and
high-redshift may be partially due to a selection effect from the limited
sensitivity of previous observations. The [CII] line of J0210-0456 is
relatively narrow (FWHM=189+/-18 km/s), indicating a dynamical mass
substantially lower than expected from the local black hole - velocity
dispersion correlation. The [CII] line is marginally resolved at 0.7"
resolution with the blue and red wings spatially offset by 0.5" (3 kpc) and a
smooth velocity gradient of 100 km/s across a scale of 6 kpc, possibly due to
rotation of a galaxy-wide disk. These observations are consistent with the idea
that stellar mass growth lags black hole accretion for quasars at this epoch
with respect to more recent times.


title: On ths assembly history of stellar components in massive galaxies

abstract:
  Matsuoka & Kawara (2010) showed that the number density of the most massive
galaxies (log M/M_sun=11.5-12.0) increases faster than that of the next massive
group (log M/M_sun=11.0-11.5) during 0 < z < 1. This appears to be in
contradiction to the apparent "downsizing effect". We attempt to understand the
two observational findings in the context of the hierarchical merger paradigm
using semi-analytic techniques. Our models closely reproduce the result of
Matsuoka & Kawara (2010). Downsizing can also be understood as larger galaxies
have, on average, smaller assembly ages but larger stellar ages. Our fiducial
models further reveal details of the history of the stellar mass growth of
massive galaxies. The most massive galaxies (log M/M_sun=11.5-12.0 at z=0),
which are mostly brightest cluster galaxies, obtain roughly 70% of their
stellar components via merger accretion. The role of merger accretion
monotonically declines with galaxy mass: 40% for log M/M_sun=11.0-11.5 and 20%
for log M/M_sun=10.5-11.0 at z=0. The specific accreted stellar mass rates via
galaxy mergers decline very slowly during the whole redshift range, while
specific star formation rates sharply decrease with time. In the case of the
most massive galaxies, merger accretion becomes the most important channel for
the stellar mass growth at z~2. On the other hand, in-situ star formation is
always the dominant channel in L* galaxies.


title: Extension of automorphisms of rational smooth affine curves

abstract:
  We provide the existence, for every complex rational smooth affine curve
$\Gamma$, of a linear action of $\mathrm{Aut}(\Gamma)$ on the affine
3-dimensional space $\mathbb{A}^3$, together with a
$\mathrm{Aut}(\Gamma)$-equivariant closed embedding of $\Gamma$ into
$\mathbb{A}^3$.
  It is not possible to decrease the dimension of the target, the reason for
this obstruction is also precisely described.


title:
Biexciton, single carrier, and trion generation dynamics in
  single-walled carbon nanotubes

abstract:
  We present a study of free carrier photo-generation and multi-carrier bound
states, such as biexcitons and trions (ionized excitons), in semiconducting
single-walled carbon nanotubes. Pump-and-probe measurements performed with fs
pulses reveal the effects of strong Coulomb interactions between carriers on
their dynamics. Biexciton formation by optical transition from exciton
population results in an induced absorption line (binding energy 130 meV).
Exciton-exciton annihilation process is shown to evolve at high densities
towards an Auger process that can expel carriers from nanotubes. The remaining
carriers give rise to an induced absorption due to trion formation (binding
energy 190 meV). These features show the dynamics of exciton and free carriers
populations.


title: Automatically Mining Program Build Information via Signature Matching

abstract:
  Program build information, such as compilers and libraries used, is vitally
important in an auditing and benchmarking framework for HPC systems. We have
developed a tool to automatically extract this information using
signature-based detection, a common strategy employed by anti-virus software to
search for known patterns of data within the program binaries. We formulate the
patterns from various "features" embedded in the program binaries, and the
experiment shows that our tool can successfully identify many different
compilers, libraries, and their versions.


title:
Required Base Station Density in Coordinated Multi-Point Uplink with
  Rate Constraints

abstract:
  In this paper we obtain the required spatial density of base stations (BSs)
in a coordinated multi-point uplink cellular network to meet a chosen quality
of service metric. Our model assumes cooperation amongst two BSs and the
required density is obtained under shadowing and Rayleigh fading for different
LTE-A path loss models. The proposed approach guarantees that the worst-case
achievable rate in the entire coverage region is above a target rate with
chosen probability. Two models for the position of the BSs are considered: a
hexagonal grid and a Poisson point process (PPP) modified to set a minimum cell
size. First, for each cooperation region, the location with the minimum rate
coverage probability - the worst-case point - is determined. Next, accurate
closed-form approximations are obtained for the worst-case rate coverage
probability. The approximations presented are useful for the quick assessment
of network performance and can be utilized in parametric studies for network
design. Here, they are applied to obtain the required density of BSs to achieve
a target rate coverage probability. As an added benefit, the formulation here
quantifies the penalty in moving from a regular BS deployment (the grid model)
to a random BS deployment (the PPP model).


title: Self-aligning universal beam coupler

abstract:
  We propose a device that can take an arbitrary monochromatic input beam and
couple it into a single-mode guide or beam. Simple feedback loops from
detectors to modulator elements allow the device to adapt automatically to any
specific input beam form. Potential applications include automatic compensation
for misalignment and defocusing of an input beam, coupling of complex modes or
multiple beams from fibers or free space to single-mode guides, and retaining
coupling to a moving source. Straightforward extensions allow multiple
different overlapping orthogonal input beams to be separated simultaneously to
different single-mode guides with no splitting loss in principle. The approach
is suitable for implementation in integrated optics platforms that offer
elements such as phase shifters, Mach-Zehnder interferometers, grating
couplers, and integrated monitoring detectors, and the basic approach is
applicable in principle to other types of waves, such as microwaves or
acoustics.


title:
Model-based scaling of the streamwise energy density in high-Reynolds
  number turbulent channels

abstract:
  We study the Reynolds number scaling and the geometric self-similarity of a
gain-based, low-rank approximation to turbulent channel flows, determined by
the resolvent formulation of McKeon & Sharma (2010), in order to obtain a
description of the streamwise turbulence intensity from direct consideration of
the Navier-Stokes equations. Under this formulation, the velocity field is
decomposed into propagating waves (with single streamwise and spanwise
wavelengths and wave speed) whose wall-normal shapes are determined from the
principal singular function of the corresponding resolvent operator. Using the
accepted scalings of the mean velocity in wall-bounded turbulent flows, we
establish that the resolvent operator admits three classes of wave parameters
that induce universal behavior with Reynolds number on the low-rank model, and
which are consistent with scalings proposed throughout the wall turbulence
literature. In addition, it was shown that a necessary condition for
geometrically self-similar resolvent modes is the presence of a logarithmic
turbulent mean velocity. We identify the scalings that constitute hierarchies
of self-similar modes that are parameterized by the critical wall-normal
location where the speed of the mode equals the local turbulent mean velocity.
For the rank-1 model subject to broadband forcing, the integrated streamwise
energy density takes a universal form which is consistent with the dominant
near-wall turbulent motions. When the shape of the forcing is optimized to
enforce matching with results from direct numerical simulations at low
turbulent Reynolds numbers, further similarity appears. Representation of these
weight functions using similarity laws enables prediction of the Reynolds
number and wall-normal variations of the streamwise energy intensity at high
Reynolds numbers (${Re}_\tau \approx 10^3 - 10^{10}$).


title: Near-IR Field Variable Stars in Cygnus OB7

abstract:
  We present a subset of the results of a three season, 124 night,
near-infrared monitoring campaign of the dark clouds Lynds 1003 and Lynds 1004
in the Cygnus OB7 star forming region. In this paper, we focus on the field
star population. Using three seasons of UKIRT J, H and K band observations
spanning 1.5 years, we obtained high-quality photometry on 9,200 stars down to
J=17 mag, with photometric uncertainty better than 0.04 mag. After excluding
known disk bearing stars we identify 149 variables - 1.6% of the sample. Of
these, about 60 are strictly periodic, with periods predominantly < 2 days. We
conclude this group is dominated by eclipsing binaries. A few stars have long
period signals of between 20 and 60 days. About 25 stars have weak modulated
signals, but it was not clear if these were periodic. Some of the stars in this
group may be diskless young stellar objects with relatively large variability
due to cool star spots. The remaining ~60 stars showed variations which appear
to be purely stochastic.


title: Tag-based Semantic Website Recommendation for Turkish Language

abstract:
  With the dramatic increase in the number of websites on the internet, tagging
has become popular for finding related, personal and important documents. When
the potentially increasing internet markets are analyzed, Turkey, in which most
of the people use Turkish language on the internet, found to be exponentially
increasing. In this paper, a tag-based website recommendation method is
presented, where similarity measures are combined with semantic relationships
of tags. In order to evaluate the system, an experiment with 25 people from
Turkey is undertaken and participants are firstly asked to provide websites and
tags in Turkish and then they are asked to evaluate recommended websites.


title:
Low-temperature criticality of martensitic transformations of Cu
  nanoprecipitates in \alpha-Fe

abstract:
  Nanoprecipitates form during nucleation of multiphase equilibria in phase
segregating multicomponent systems. In spite of their ubiquity, their
size-dependent physical chemistry, in particular at the boundary between phases
with incompatible topologies, is still rather arcane. Here we use extensive
atomistic simulations to map out the size-temperature phase diagram of Cu
nanoprecipitates in \alpha-Fe. The growing precipitates undergo martensitic
transformations from the body-centered cubic (BCC) phase to multiply-twinned 9R
structures. At high temperatures, the transitions exhibit strong first-order
character and prominent hysteresis. Upon cooling the discontinuities become
less pronounced and the transitions occur at ever smaller cluster sizes. Below
300 K the hysteresis vanishes while the transition remains discontinuous with a
finite but diminishing latent heat. This unusual size-temperature phase diagram
results from the entropy generated by the soft modes of the BCC-Cu phase, which
are stabilized through confinement by the \alpha-Fe lattice.


title: Exact Lagrangians in $A_n$-surface singularities

abstract:
  In this paper we classify Lagrangian spheres in $A_n$-surface singularities
up to Hamiltonian isotopy. Combining with a result of A. Ritter, this yields a
complete classification of exact Lagrangians in $A_n$-surface singularities.


title: Radon Numbers for Trees

abstract:
  Many interesting problems are obtained by attempting to generalize classical
results on convexity in Euclidean spaces to other convexity spaces, in
particular to convexity spaces on graphs. In this paper we consider
$P_3$-convexity on graphs. A set $U$ of vertices in a graph $G$ is $P_3$-convex
if every vertex not in $U$ has at most one neighbour in $U$. More specifically,
we consider Radon numbers for $P_3$-convexity in trees.
  Tverberg's theorem states that every set of $(k-1)(d+1)-1$ points in
$\mathbb{R}^d$ can be partitioned into $k$ sets with intersecting convex hulls.
As a special case of Eckhoff's conjecture, we show that a similar result holds
for $P_3$-convexity in trees.
  A set $U$ of vertices in a graph $G$ is called free, if no vertex of $G$ has
more than one neighbour in $U$. We prove an inequality relating the Radon
number for $P_3$-convexity in trees with the size of a maximal free set.


title: Broken Chiral Symmetry on a Null Plane

abstract:
  On a null-plane (light-front), all effects of spontaneous chiral symmetry
breaking are contained in the three Hamiltonians (dynamical Poincar\'e
generators), while the vacuum state is a chiral invariant. This property is
used to give a general proof of Goldstone's theorem on a null-plane. Focusing
on null-plane QCD with N degenerate flavors of light quarks, the
chiral-symmetry breaking Hamiltonians are obtained, and the role of vacuum
condensates is clarified. In particular, the null-plane Gell-Mann-Oakes-Renner
formula is derived, and a general prescription is given for mapping all
chiral-symmetry breaking QCD condensates to chiral-symmetry conserving
null-plane QCD condensates. The utility of the null-plane description lies in
the operator algebra that mixes the null-plane Hamiltonians and the chiral
symmetry charges. It is demonstrated that in a certain non-trivial limit, the
null-plane operator algebra reduces to the symmetry group SU(2N) of the
constituent quark model.


title: On the Capacity Region for Index Coding

abstract:
  A new inner bound on the capacity region of a general index coding problem is
established. Unlike most existing bounds that are based on graph theoretic or
algebraic tools, the bound is built on a random coding scheme and optimal
decoding, and has a simple polymatroidal single-letter expression. The utility
of the inner bound is demonstrated by examples that include the capacity region
for all index coding problems with up to five messages (there are 9846
nonisomorphic ones).


title: Noise assisted transport in the Wannier-Stark system

abstract:
  We investigated how the presence of an additional lattice potential, driven
by a harmonic noise process, changes the transition rate from the ground band
to the first excited band in a Wannier-Stark system. Alongside numerical
simulations, we present two models that capture the essential features of the
dynamics. The first model uses a noise-driven Landau-Zener approximation and
describes the short time evolution of the full system very well. The second
model assumes that the noise process' correlation time is much larger than the
internal timescale of the system, yet it allows for good estimates of the
observed transition rates and gives a simple interpretation of the dynamics.
One of the central results is that we obtain a way to control the interband
transitions with the help of the second lattice. This could readily be realized
in state-of-the-art experiments using either Bose-Einstein condensates or
optical pulses in engineered potentials.


title: A response to an article of Xu-Jia Wang

abstract:
  This is a response to the article arXiv:1212.3130v1 by Xu-Jia Wang, where he
attempted to address a mathematical question we raised. We point out that, and
explain why, the article is far from answering our objections. Moreover, we
have more recently found more serious trouble in the paper under discussion
based on the false assertion there that minimal radial functions of
superharmonic functions (with respect to a conformal Laplacian of a Riemannian
metric) are superharmonic.


title: The Minimum Size of Qubit Unextendible Product Bases

abstract:
  We investigate the problem of constructing unextendible product bases in the
qubit case - that is, when each local dimension equals 2. The cardinality of
the smallest unextendible product basis is known in all qubit cases except when
the number of parties is a multiple of 4 greater than 4 itself. We construct
small unextendible product bases in all of the remaining open cases, and we use
graph theory techniques to produce a computer-assisted proof that our
constructions are indeed the smallest possible.


title: Self-passivation of vacancies in \alpha-PbO

abstract:
  We introduce a self-passivation of single lead (Pb) and oxygen (O) vacancies
in the \alpha-PbO compound through formation of a Pb-O vacancy pair. The
preferential mechanism for pair formation involves initial development of the
single Pb vacancy which, by weakening the covalent bonding, sets up the crystal
lattice for an appearance of the O vacancy. Binding of the Pb and O vacancies
occurs through the ionization interactions. Since no dangling bonds appear at
the Pb-O pair site, this defect has a minor effect on the electronic
properties. In such, vacancy self-passivation offers a practical way to improve
the transport properties in thermally grown PbO layers.


title:
A statistical model approximation for perovskite solid-solutions: a
  Raman study of lead-zirconate-titanate single crystal

abstract:
  Lead titanate (PbTiO3) is a classical example of a ferroelectric perovskite
oxide illustrating a displacive phase transition accompanied by a softening of
a symmetry-breaking mode. The underlying assumption justifying the soft-mode
theory is that the crystal is macroscopically sufficiently uniform so that a
meaningful free energy function can be formed. In contrast to PbTiO3,
experimental studies show that the phase transition behaviour of
lead-zirconate-titanate solid solution (PZT) is far more subtle. Most of the
studies on the PZT system have been dedicated to ceramic or powder samples, in
which case an unambiguous soft-mode study is not possible, as modes with
different symmetries appear together. Our Raman scattering study on
titanium-rich PZT single crystal shows that the phase transitions in PZT cannot
be described by a simple soft-mode theory. In strong contrast to PbTiO3,
splitting of transverse E-symmetry modes reveals that there are different
locally-ordered regions. The role of crystal defects, random distribution of Ti
and Zr at the B-cation site and Pb ions shifted away from their ideal
positions, dictates the phase transition mechanism. A statistical model
explaining the observed peak splitting and phase transformation to a complex
state with spatially varying local order in the vicinity of the morphotropic
phase boundary is given.


title:
Configuration dependent demagnetizing field in assemblies of interacting
  magnetic particles

abstract:
  A mean field model is presented for the configuration dependent effective
demagnetizing and anisotropy fields in assemblies of exchange decoupled
magnetic particles of arbitrary shape which are expressed in terms of the
demagnetizing factors of the particles and the volumetric shape containing the
assembly. Perpendicularly magnetized 2D assemblies have been considered, for
which it is shown that the demagnetizing field is lower than the continuous
thin film. As an example of these 2D systems, arrays of bistable cylindrical
nanowires have been characterized by remanence curves as well as ferromagnetic
resonance, which have served to show the correspondence of these measurements
with the model and also to validate the mean field approach. Linear chains of
cylinders and spheres have been analyzed leading to simple expressions to
describe the easy axis rotation induced by the interaction field in chains of
low aspect ratio cylindrical particles, and the dipolar magnetic anisotropy
observed in the linear chain of spheres. These examples serve to underline the
dependence on the dipolar interaction field and effective demagnetizing factor
on the contributions that arise from the shape of the outer volume.


title:
Inconsistency of the photoemission spectrum with the spectral function
  in Kondo systems

abstract:
  Kondo effect is an example of asymptotic freedom where the antiferromagnetic
coupling between a localized magnetic moment and valence electrons, increases
with reducing temperature. The electronic spectral function for such a system
predicts a narrow Kondo resonance close to Fermi energy below its Kondo
temperature 'TK'. The internal energy level structure of the localized magnetic
moment introduces sidebands near the Kondo resonance, each with its respective
Kondo temperature increasing as the sideband position moves towards higher
binding energies. Consequently, the temperature dependence of the resonance
features becomes weaker as we go towards higher binding energies. Here, we show
a Ce4f photoemission spectral evolution obtained from a prototypical Kondo
system CeAl2, departing from the predictions of the spectral function. Our
measurements reveal a uniform temperature dependence for all the well screened
Ce4f photoemission features (4f1 final state), which are usually interpreted as
resonance features, as we reduce the temperature suggesting that the resonance
interpretation for the 4f1 final state features is not appropriate. Instead,
the spectral evolution is explained simply by the temperature dependence of the
strength of the coupling between Ce4f and valence electrons, which remains
uniform over the range of 4f1 final state features. As a possible explanation
to the observed spectral evolution, we propose the phenomenon of collapse of
the Kondo singlet wave function upon photoelectron kinetic energy measurement,
analogous to the wave function collapse observed upon measurements performed on
an entangled EPR (Einstein, Podolsky, Rosen) pair. Our proposal highlights how
experiments studying single particle properties, when performed on a quantum
system, give incomplete information about the many-body physics of the system.


title: Evolution of the Cosmological Horizons in a Concordance Universe

abstract:
  The particle and event horizons are widely known and studied concepts, but
the study of their properties, in particular their evolution, have only been
done so far considering a single state equation in a decelerating universe.
This paper is the first of two where we study this problem from a general point
of view. Specifically, this paper is devoted to the study of the evolution of
these cosmological horizons in an accelerated universe with two state
equations, cosmological constant and dust. We have obtained closed-form
expressions for the horizons, which have allowed us to compute their velocities
in terms of their respective recession velocities that generalize the previous
results for one state equation only. With the equations of state considered, it
is proved that both velocities remain always positive.


title:
Adaptive low rank and sparse decomposition of video using compressive
  sensing

abstract:
  We address the problem of reconstructing and analyzing surveillance videos
using compressive sensing. We develop a new method that performs video
reconstruction by low rank and sparse decomposition adaptively. Background
subtraction becomes part of the reconstruction. In our method, a background
model is used in which the background is learned adaptively as the compressive
measurements are processed. The adaptive method has low latency, and is more
robust than previous methods. We will present experimental results to
demonstrate the advantages of the proposed method.


title: Bounded regret in stochastic multi-armed bandits

abstract:
  We study the stochastic multi-armed bandit problem when one knows the value
$\mu^{(\star)}$ of an optimal arm, as a well as a positive lower bound on the
smallest positive gap $\Delta$. We propose a new randomized policy that attains
a regret {\em uniformly bounded over time} in this setting. We also prove
several lower bounds, which show in particular that bounded regret is not
possible if one only knows $\Delta$, and bounded regret of order $1/\Delta$ is
not possible if one only knows $\mu^{(\star)}$


title:
Arabic text summarization based on latent semantic analysis to enhance
  arabic documents clustering

abstract:
  Arabic Documents Clustering is an important task for obtaining good results
with the traditional Information Retrieval (IR) systems especially with the
rapid growth of the number of online documents present in Arabic language.
Documents clustering aim to automatically group similar documents in one
cluster using different similarity/distance measures. This task is often
affected by the documents length, useful information on the documents is often
accompanied by a large amount of noise, and therefore it is necessary to
eliminate this noise while keeping useful information to boost the performance
of Documents clustering. In this paper, we propose to evaluate the impact of
text summarization using the Latent Semantic Analysis Model on Arabic Documents
Clustering in order to solve problems cited above, using five
similarity/distance measures: Euclidean Distance, Cosine Similarity, Jaccard
Coefficient, Pearson Correlation Coefficient and Averaged Kullback-Leibler
Divergence, for two times: without and with stemming. Our experimental results
indicate that our proposed approach effectively solves the problems of noisy
information and documents length, and thus significantly improve the clustering
performance.


title:
Metallicity gradients through disk Instability: A simple model for the
  Milky Way's boxy bulge

abstract:
  Observations show a clear vertical metallicity gradient in the Galactic
bulge, which is often taken as a signature of dissipative processes in the
formation of a classical bulge. Various evidence shows, however, that the Milky
Way is a barred galaxy with a boxy bulge representing the inner
three-dimensional part of the bar. Here we show with a secular evolution N-body
model that a boxy bulge formed through bar and buckling instabilities can show
vertical metallicity gradients similar to the observed gradient, if the initial
axisymmetric disk had a comparable radial metallicity gradient. In this
framework the range of metallicities in bulge fields constrains the chemical
structure of the Galactic disk at early times, before bar formation. Our
secular evolution model was previously shown to reproduce inner Galaxy star
counts and we show here that it also has cylindrical rotation. We use it to
predict a full mean metallicity map across the Galactic bulge from a simple
metallicity model for the initial disk. This map shows a general outward
gradient on the sky as well as longitudinal perspective asymmetries. We also
briefly comment on interpreting metallicity gradient observations in external
boxy bulges.


title: A \mu-ordinary Hasse invariant

abstract:
  We construct a generalization of the Hasse invariant for certain unitary
Shimura varieties of PEL type whose vanishing locus is the complement of the
so-called \mu-ordinary locus. We show that the \mu-ordinary locus of those
varieties is affine. As an application, we strengthen a special case of a
theorem of one of us (W.G.) on the association of Galois representations to
automorphic representations of unitary groups whose archimedean component is a
holomorphic limit of discrete series.


title:
Combined evanescent-wave excitation and supercritical-angle fluorescence
  detection improves optical sectioning

abstract:
  Evanescent-wave microscopy achieves sub-diffraction axial sectioning by
confining fluorescence excitation to a thin layer close to the cell/substrate
interface. How thin this light sheet exactly is, however, is often unknown.
Particularly in the popular objective-type total internal reflection
fluorescence microscopy (TIRFM) configuration large deviations from the
expected exponential intensity decay of the evanescent wave have been reported.
Propagating, i.e., non-evanescent, excitation light diminishes the optical
sectioning effect, reduces contrast and renders the quantification of TIRFM
images uncertain. Here, we use a combination of azimuthal- and polar-angle beam
scanning, dark-field scatter imaging, and atomic force microscopy to identify
the sources of this unwanted background fluorescence excitation. We identify
stray light originating from the microscope optics and the objective lens
itself as the major sources of background, with minor contributions due to
evanescent-wave scattering at the reflecting interface and at refractive-index
boundaries in the sample. Apart from evanescence in excitation light, light
emitted from a fluorophore can also show observable effects of evanescence.
Only fluorophores located close to the coverslip can couple their near-field
radiation into propagating waves detectable at supercritical angles. We show
that selectively detecting this supercritical-angle fluorescence (SAF) through
a high-numerical aperture objective effectively rejects fluorescence from
deeper sample regions and improves optical sectioning. The microscopy scheme
presented here merges the benefits of TIRF excitation and SAF detection and
provides the conditions for quantitative wide-field imaging of fluorophore
dynamics at or near the plasma membrane.


title:
Sensor Selection Based on Generalized Information Gain for Target
  Tracking in Large Sensor Networks

abstract:
  In this paper, sensor selection problems for target tracking in large sensor
networks with linear equality or inequality constraints are considered. First,
we derive an equivalent Kalman filter for sensor selection, i.e., generalized
information filter. Then, under a regularity condition, we prove that the
multistage look-ahead policy that minimizes either the final or the average
estimation error covariances of next multiple time steps is equivalent to a
myopic sensor selection policy that maximizes the trace of the generalized
information gain at each time step. Moreover, when the measurement noises are
uncorrelated between sensors, the optimal solution can be obtained analytically
for sensor selection when constraints are temporally separable. When
constraints are temporally inseparable, sensor selections can be obtained by
approximately solving a linear programming problem so that the sensor selection
problem for a large sensor network can be dealt with quickly. Although there is
no guarantee that the gap between the performance of the chosen subset and the
performance bound is always small, numerical examples suggest that the
algorithm is near-optimal in many cases. Finally, when the measurement noises
are correlated between sensors, the sensor selection problem with temporally
inseparable constraints can be relaxed to a Boolean quadratic programming
problem which can be efficiently solved by a Gaussian randomization procedure
along with solving a semi-definite programming problem. Numerical examples show
that the proposed method is much better than the method that ignores dependence
of noises.


title: What if Planck's Universe isn't flat?

abstract:
  Inflationary theory predicts that the observable Universe should be very
close to flat, with a spatial-curvature parameter |Omega_K| < 10^-4. The WMAP
satellite currently constrains |Omega_K| < 0.01, and the Planck satellite will
be sensitive to values near 10^-3. Suppose that Planck were to find Omega_K to
be non-zero at this level. Would this necessarily be a serious problem for
inflation? We argue that an apparent departure from flatness could be due
either to a local (wavelength comparable to the observable horizon)
inhomogeneity, or a truly superhorizon departure from flatness. If there is a
local inhomogeneity, then secondary CMB anisotropies distort the CMB frequency
spectrum at a level potentially detectable by a next-generation experiment. We
discuss how these spectral distortions would complement constraints on the
Grishchuk-Zel'dovich effect from the CMB power spectrum at large angular scales
in discovering the source of the departure from flatness.


title:
Parabolic isometries of visible CAT(0) spaces and metrics on moduli
  space

abstract:
  We show that the translation length of any parabolic isometry on a complete
semi-uniformly visible CAT(0) space is always zero. As a consequence, we will
classify the isometries on visible CAT(0) spaces in terms of translation
lengths. We will also show that the moduli space $\mathbb{M}(S_{g,n})$ of
surface $S_{g,n}$ of $g$ genus with $n$ punctures admits no complete visible
CAT(0) Riemannian metric if $3g+n\geq 5$, which answers the Brock-Farb-McMullen
question in the visible case.


title: Untersuchungen zur Sprechtraktakustik

abstract:
  This thesis investigates acoustic properties of the vocal tract. Starting
from a historical background (to name a few: Galen, Ibn Sina/Avicenna,
Mersenne, Hooke, Euler, Kempelen, Abbe Mical, Kratzenstein, Wheatstone,
Helmholtz, Riesz, Dudley, Dunn, Kelly, Lochbaum, Chiba, Kajiyama, Saito,
Itakura, Burg, Gray...) finaly an improvement in respect to the tube model of
the vocal tract is developed: The acoustics of vocal tract is numerical
simulated in 3 dimensions with Finite-difference in time-domain (FDTD) applied
on an oral-cavity spatially constructed by parameter estimation of speech
signals and laterally by MRI (Magnet Resonance Imaging). Further, the FDTD is
applied on the acoustics of the nasal tract, including paranasal cavities. The
spatial properties of the nasal tract are drawn for CT (Computer Tomographies).
It is shown, that the (absolute) cross section area influences the resonance
charateritic of the vocal tract significant, further the actual shape of the
cross section introduces zeros in the transfer functions. The shape can be
approximated by an elliptical contour, and a 2 dimensional FDTD approach is
discussed. Important absorption machanism are modeled, and a method to
translate the hounsfield-value of a voxel to an acoustic impedance, is shown,
which leads to a more accurate simulation. The thesis further elucidates some
aspects of a numerical efficient FDTD-implementation.


title: Secular Orbital Evolution of Compact Planet Systems

abstract:
  Recent observations have shown that at least some close-in exoplanets
maintain eccentric orbits despite tidal circularization timescales that are
typically shorter than stellar ages. We explore gravitational interactions with
a distant planetary companion as a possible cause of these non-zero
eccentricities. For simplicity, we focus on the evolution of a planar
two-planet system subject to slow eccentricity damping and provide an intuitive
interpretation of the resulting long-term orbital evolution. We show that
dissipation shifts the two normal eigenmode frequencies and eccentricity ratios
of the standard secular theory slightly, and that each mode decays at its own
rate. Tidal damping of the eccentricities drives orbits to transition between
periods of pericenter circulation and libration, and the planetary system
settles into a locked state where the pericenters are nearly aligned or
anti-aligned. Once in the locked state, the eccentricities of the two orbits
decrease very slowly due to tides rather than at the much more rapid
single-planet rate, and thus eccentric orbits, even for close-in planets, can
often survive much longer than the age of the system. Assuming that an observed
close-in planet on an elliptical orbit is apsidally-locked to a more distant,
and perhaps unseen companion, we provide a constraint on the mass, semi-major
axis, and eccentricity of the companion. We find the observed two-planet system
HAT-P-13 might be in just such an apsidally-locked state, with parameters that
obey our constraint well. We also survey close-in single planets, and found
that none provide compelling evidence for unseen companions. Instead, we
suspect that (1) orbits are circular, (2) tidal damping rates are slower than
our assumption, or (3) a recent event has excited these eccentricities. Our
method should prove useful for interpreting the results of current and future
planet searches.


title: Non-linear noise excitation and intermittency under high disorder

abstract:
  Consider the semilinear heat equation $\partial_t u = \partial^2_x u +
\lambda\sigma(u)\xi$ on the interval $[0\,,1]$ with Dirichlet zero boundary
condition and a nice non-random initial function, where the forcing $\xi$ is
space-time white noise and $\lambda>0$ denotes the level of the noise. We show
that, when the solution is intermittent [that is, when
$\inf_z|\sigma(z)/z|>0$], the expected $L^2$-energy of the solution grows at
least as $\exp\{c\lambda^2\}$ and at most as $\exp\{c\lambda^4\}$ as
$\lambda\to\infty$. In the case that the Dirichlet boundary condition is
replaced by a Neumann boundary condition, we prove that the $L^2$-energy of the
solution is in fact of sharp exponential order $\exp\{c\lambda^4\}$. We show
also that, for a large family of one-dimensional randomly-forced wave
equations, the energy of the solution grows as $\exp\{c\lambda\}$ as
$\lambda\to\infty$. Thus, we observe the surprising result that the stochastic
wave equation is, quite typically, significantly less noise-excitable than its
parabolic counterparts.


title:
Thirring model at finite density in 0+1 dimensions with stochastic
  quantization: Crosscheck with an exact solution

abstract:
  We consider a generalized Thirring model in 0+1 dimensions at finite density.
In order to deal with the resulting sign problem we employ stochastic
quantization, i.e., a complex Langevin evolution. We investigate the
convergence properties of this approach and check in which parameter regions
complex Langevin evolutions are applicable in this setting. To this end we
derive numerous analytical results and compare directly with numerical results.
In addition we employ indirect indicators to check for correctness. Finally we
interpret and discuss our findings.


title:
Integrated Differential Optical Shadow Sensor for Modular Gravitational
  Reference Sensor

abstract:
  The Laser Interferometer Space Antenna (LISA) is a proposed space mission for
the detection of gravitational waves. It consists of three drag-free satellites
flying in a triangular constellation. A gravitational reference sensor is used
in conjunction with a laser interferometer to measure the distance between test
masses inside the three satellites. Other future space mission such as DECIGO
and BBO also require a gravitational reference sensor. The Modular
Gravitational Reference Sensor (MGRS) is being designed for these purposes and
consists of two different optical sensors and a UV LED charge management
system. The Differential Optical Shadow Sensor (DOSS) is one of the optical
sensors and measures the position of a spherical test mass with respect to the
surrounding satellite. This measurement is used for the drag-free feedback
control loop. This paper describes the most recent, third generation of the
experimental setup for the DOSS that uses a fiber coupled super luminescent
LED, an integrated mounting structure and lock-in amplification. The achieved
sensitivity is 10 nm/Hz^(1/2) above 300 mHz, and 20 nm/Hz^(1/2) for frequencies
above 30 mHz.


title: Gaussian Quantum Reading beyond the Standard Quantum Limit

abstract:
  Quantum reading aims at retrieving classical information stored in an optical
memory with low energy and high accuracy by exploiting the inherently quantum
properties of light. We provide an optimal Gaussian strategy for quantum
reading with phase-shift keying encoding that makes use of squeezed coherent
light and homodyne detectors to largely outperform the Standard Quantum Limit,
even in the presence of loss. This strategy, being feasible with current
quantum optical technology, represents a viable prototype for a highly
efficient and reliable quantum-enhanced optical reader.


title: Public Key Exchange Using Matrices Over Group Rings

abstract:
  We offer a public key exchange protocol in the spirit of Diffie-Hellman, but
we use (small) matrices over a group ring of a (small) symmetric group as the
platform. This "nested structure" of the platform makes computation very
efficient for legitimate parties. We discuss security of this scheme by
addressing the Decision Diffie-Hellman (DDH) and Computational Diffie-Hellman
(CDH) problems for our platform.


title:
On the Classification of Extremal Doubly Even Self-Dual Codes with
  2-Transitive Automorphism Group

abstract:
  In this note, we complete the classification of extremal doubly even
self-dual codes with 2-transitive automorphism groups.


title: The interior regularity of the Calabi flow on a toric surface

abstract:
  Let X be a toric surface with Delzant polygon P and u(t) be a solution of the
Calabi flow equation on P. Suppose the Calabi flow exists in [0, T). By
studying local estimates of the Riemann curvature and the geodesic distance
under the Calabi flow, we prove a uniform interior estimate of u(t) for t < T.


title: Hydrogen atom as a quantum-classical hybrid system

abstract:
  Hydrogen atom is studied as a quantum-classical hybrid system, where the
proton is treated as a classical object while the electron is regarded as a
quantum object. We use a well known mean-field approach to describe this hybrid
hydrogen atom; the resulting dynamics for the electron and the proton is
compared to their full quantum dynamics. The electron dynamics in the hybrid
description is found to be only marginally different from its full quantum
counterpart. The situation is very different for the proton: in the hybrid
description, the proton behaves like a free particle; in the fully quantum
description, the wave packet center of the proton orbits around the center of
mass. Furthermore, we find that the failure to describe the proton dynamics
properly can be regarded as a manifestation of the fact that there is no
conservation of momentum in the mean-field hybrid approach. We expect that such
a failure is a common feature for all existing approaches for quantum-classical
hybrid systems of Born-Oppenheimer type.


title: Non-expander Cayley graphs of simple groups

abstract:
  For every infinite sequence of simple groups of Lie type of growing rank we
exhibit connected Cayley graphs of degree at most 10 such that the
isoperimetric number of these graphs converges to 0. This proves that these
graphs do not form a family of expanders.


title: Euclidean plane and its relatives; a minimalist introduction

abstract:
  The book is designed for a semester-long course in Foundations of Geometry
and meant to be rigorous, conservative, elementary and minimalist.
  List of topics:
  Euclidean geometry: The Axioms / Half-planes / Congruent triangles /
Perpendicular lines / Similar triangles / Parallel lines / Triangle geometry.
  Inversive geometry: Inscribed angles / Inversion.
  Non-Euclidean geometry: Neutral plane / Hyperbolic plane / Geometry of
h-plane.
  Additional topics: Affine geometry / Projective geometry / Spherical geometry
/ Projective model / Complex coordinates / Geometric constructions / Area.


title: On the twisted Alexander polynomial for representations into SL_2(C)

abstract:
  We study the twisted Alexander polynomial $\Delta_{K,\rho}$ of a knot $K$
associated to a non-abelian representation $\rho$ of the knot group into
$SL_2(\BC)$. It is known for every knot $K$ that if $K$ is fibered, then for
every non-abelian representation, $\Delta_{K,\rho}$ is monic and has degree
$4g(K)-2$ where $g(K)$ is the genus of $K$. Kim and Morifuji recently proved
the converse for 2-bridge knots. In fact they proved a stronger result: if a
2-bridge knot $K$ is non-fibered, then all but finitely many non-abelian
representations on some component have $\Delta_{K,\rho}$ non-monic and degree
$4g(K)-2$. In this paper, we consider two special families of non-fibered
2-bridge knots including twist knots. For these families, we calculate the
number of non-abelian representations where $\Delta_{K,\rho}$ is monic and
calculate the number of non-abelian representations where the degree of
$\Delta_{K,\rho}$ is less than $4g(K)-2$.


title:
Twisted Alexander polynomials with the adjoint action for some classes
  of knots

abstract:
  We calculate the twisted Alexander polynomial with the adjoint action for
torus knots and twist knots. As consequences of these calculations, we obtain
the formula for the nonabelian Reidemeister torsion of torus knots in \cite{Du}
and a formula for the nonabelian Reidemeister torsion of twist knots that is
better than the one in \cite{DHY}.


title: On the Schr\"{o}dinger group

abstract:
  In this paper, we compute the Leibniz homology of the Schr\"{o}dinger
algebra. We show that it is a graded vector space generated by tensors in
dimensions $2n-2$ and $2n$. The Leibniz homology of the full Galilei algebra is
also calculated.


title: Hypergraph limits: a regularity approach

abstract:
  A sequence of $k$-uniform hypergraphs $H_1, H_2, \dots$ is convergent if the
sequence of homomorphism densities $t(F, H_1), t(F, H_2), \dots$ converges for
every $k$-uniform hypergraph $F$. For graphs, Lov\'asz and Szegedy showed that
every convergent sequence has a limit in the form of a symmetric measurable
function $W \colon [0,1]^2 \to [0,1]$. For hypergraphs, analogous limits $W
\colon [0,1]^{2^k-2} \to [0,1]$ were constructed by Elek and Szegedy using
ultraproducts. These limits had also been studied earlier by Hoover, Aldous,
and Kallenberg in the setting of exchangeable random arrays.
  In this paper, we give a new proof and construction of hypergraph limits. Our
approach is inspired by the original approach of Lov\'asz and Szegedy, with the
key ingredient being a weak Frieze-Kannan type regularity lemma.


title:
Comment on "Is a system's wave function in one-to-one correspondence
  with its elements of reality?" [arXiv:1111.6597]

abstract:
  Recently, it has been argued [arXiv:1111.6597, arXiv:1005.5173] that
different quantum states do necessarily correspond to different elements of
reality, under the assumption that quantum mechanics is correct and that
measurement settings can be freely chosen. Here, we prove that additional
assumptions are necessary to derive this results, which then has not general
validity.


title:
Crystal Structure and Magnetic Properties of the Ba3TeCo3P2O14,
  Pb3TeCo3P2O14, and Pb3TeCo3V2O14 Langasites

abstract:
  We report the structural and magnetic characterizations of Ba3TeCo3P2O14,
Pb3TeCo3P2O14, and Pb3TeCo3V2O14, compounds that are based on the mineral
Dugganite, which is isostructural to Langasites. The magnetic part of the
structure consists of layers of Co2+ triangles. Nuclear and magnetic structures
were determined through a co-refinement of synchrotron and neutron powder
diffraction data. In contrast to the undistorted P321 Langasite structure of
Ba3TeCo3P2O14, a complex structural distortion yielding a large supercell is
found for both Pb3TeCo3P2O14 and Pb3TeCo3V2O14. Comparison of the three
compounds studied along with the zinc analog Pb3TeZn3P2O14, also characterized
here, suggests that the distortion is driven by Pb2+ lone pairs; as such, the
Pb compounds crystallize in a pyroelectric space group, P2. Magnetic
susceptibility, magnetization, and heat capacity measurements were performed to
characterize the magnetic behavior. All three compounds become
antiferromagnetic with N\'eel temperatures TN ~ 21 K (Ba3TeCo3P2O14), ~ 13 K
(Pb3TeCo3P2O14), and ~ 8 K (Pb3TeCo3V2O14), and they exhibit magnetic
transitions at high applied magnetic fields, suggesting intrinsically complex
magnetic behavior for tetrahedrally coordinated d7 Co2+ in this structure type.


title: Center foliation: absolute continuity, disintegration and rigidity

abstract:
  In this paper we address the issues of absolute continuity for the center
foliation (as well as the disintegration on the non-absolute continuous case)
and rigidity of volume preserving partially hyperbolic diffeomorphisms isotopic
to a linear Anosov on $\mathbb T^3$. It is shown that the disintegration of
volume on center leaves may be neither atomic nor Lebesgue. It is also obtained
results concerning the atomic disintegration. Moreover, the absolute continuity
of the center foliation does not imply smooth conjugacy with its linearization.
Imposing stronger conditions besides absolute continuity on the center
foliation, smooth conjugacy is obtained.


title: Discovery of Maximal Frequent Item Sets using Subset Creation

abstract:
  Data mining is the practice to search large amount of data to discover data
patterns. Data mining uses mathematical algorithms to group the data and
evaluate the future events. Association rule is a research area in the field of
knowledge discovery. Many data mining researchers had improved upon the quality
of association rule for business development by incorporating influential
factors like utility, number of items sold and for the mining of association
data patterns. In this paper, we propose an efficient algorithm to find maximal
frequent itemset first. Most of the association rule algorithms used to find
minimal frequent item first, then with the help of minimal frequent itemsets
derive the maximal frequent itemsets, these methods consume more time to find
maximal frequent itemsets. To overcome this problem, we propose a new approach
to find maximal frequent itemset directly using the concepts of subsets. The
proposed method is found to be efficient in finding maximal frequent itemsets.


title: On the smooth transfer for Guo-Jacquet relative trace formulae

abstract:
  We establish the existence of smooth transfer for Guo-Jacquet relative trace
formulae in $p$-adic case. This kind of smooth transfer is a key step towards a
generalization of Waldspurger's result on central values of L-functions of
$GL_2$.


title: Mass-Dependent Baryon Acoustic Oscillation Signal and Halo Bias

abstract:
  We characterize the baryon acoustic oscillations (BAO) feature in halo
two-point statistics using N-body simulations. We find that nonlinear damping
of the BAO signal is less severe for halos in the mass range we investigate
than for dark matter. The amount of damping depends weakly on the halo mass.
The correlation functions show a mass-dependent drop of the halo clustering
bias below roughly 90 Mpc/h, which coincides with the scale of the BAO trough.
The drop of bias is 4% for halos with mass M>10^{14} Msun/h and reduces to
roughly 2% for halos with mass M>10^{13} Msun/h. In contrast, halo biases in
simulations without BAO change more smoothly around 90 Mpc/h. In Fourier space,
the bias of M>10^{14} Msun/h halos decreases smoothly by 11% from wavenumber k
= 0.012 h/Mpc to 0.2 h/Mpc, whereas that of M>10^{13} Msun/h halos decreases by
less than 4% over the same range. By comparing the halo biases in pairs of
otherwise identical simulations, one with and the other without BAO, we also
observe a modulation of the halo bias. These results suggest that precise
calibrations of the mass-dependent BAO signal and scale-dependent bias on large
scales would be needed for interpreting precise measurements of the two-point
statistics of clusters or massive galaxies in the future.


title:
Membrane mediated aggregation of curvature inducing nematogens and
  membrane tubulation

abstract:
  The shapes of cell membranes are largely regulated by membrane associated,
curvature active, proteins. We use a numerical model of the membrane with
elongated membrane inclusions, recently developed by us, which posses
spontaneous directional curvatures that could be different along and
perpendicular to its long axis. We show that, due to membrane mediated
interactions these curvature inducing membrane nematogens can oligomerize
spontaneously, even at low concentrations, and change the local shape of the
membrane. We demonstrate that for a large group of such inclusions, where the
two spontaneous curvatures have equal sign, the tubular conformation and
sometime the sheet conformation of the membrane are the common equilibrium
shapes. We elucidate the factors necessary for the formation of these {\it
protein lattices}. Furthermore, the elastic properties of the tubes, like their
compressional stiffness and persistence length are calculated. Finally, we
discuss the possible role of nematic disclination in capping and branching of
the tubular membranes.


title:
The Affects of Different Queuing Algorithms within the Router on QoS
  VoIP application Using OPNET

abstract:
  Voice over Internet Protocol is a service from the Internet services that
allows users to communicate with each other. Quality of Service is very
sensitive to delay so that Voice over Internet Protocol needs it. The objective
of this research is to study the effect of different queuing algorithms within
the router on Voice over Internet Protocol Quality of Service. In this work,
simulation tool OPNET Modeler is used to implement the proposed network (Voice
over Internet Protocol Network). The proposed network is a private network for
a company that has two locations located at two different countries around the
world in order to simulate the communications within the same location as a
local and the communications between two locations as a long distance and
analyze Voice over Internet Protocol Quality of Service through measuring the
major factors that affect the Quality of Service for Voice over Internet
Protocol according to international telecommunication union standards such as:
delay, jitter and packet loss. In this research, a comparison was carried out
between different queue algorithms like First in First out (FIFO), Priority
queue and Weight Fair Queuing and it was found that Priority queue and Weight
Fair Queuing algorithms are the most appropriate to improve Voice over Internet
Protocol Quality of Service .