title: Understanding Robust Control Theory Via Stick Balancing

abstract:
  Robust control theory studies the effect of noise, disturbances, and other
uncertainty on system performance. Despite growing recognition across science
and engineering that robustness and efficiency tradeoffs dominate the evolution
and design of complex systems, the use of robust control theory remains
limited, partly because the mathematics involved is relatively inaccessible to
nonexperts, and the important concepts have been inexplicable without a fairly
rich mathematics background. This paper aims to begin changing that by
presenting the most essential concepts in robust control using human stick
balancing, a simple case study popular in both the sensorimotor control
literature and extremely familiar to engineers. With minimal and familiar
models and mathematics, we can explore the impact of unstable poles and zeros,
delays, and noise, which can then be easily verified with simple experiments
using a standard extensible pointer. Despite its simplicity, this case study
has extremes of robustness and fragility that are initially counter-intuitive
but for which simple mathematics and experiments are clear and compelling. The
theory used here has been well-known for many decades, and the cart-pendulum
example is a standard in undergrad controls courses, yet a careful
reconsidering of both leads to striking new insights that we argue are of great
pedagogical value.


title: Quasi-thin weakly distance-regular digraphs,I

abstract:
  A weakly distance-regular digraph is quasi-thin if the maximum value of its
intersection numbers is 2. In this paper, we show that the valency of any
commutative quasi-thin weakly distance-regular digraph is at most 6.


title: A Simple Analytical Model for Rocky Planet Interiors

abstract:
  This work aims at exploring the scaling relations among rocky exoplanets.
With the assumption of internal gravity increasing linearly in the core, and
staying constant in the mantle, and tested against numerical simulations, a
simple model is constructed, applicable to rocky exoplanets of core mass
fraction (CMF) $\in 0.1\sim0.4$ and mass $\in 0.1 \sim 10 M_{\oplus}$. Various
scaling relations are derived: (1) core radius fraction $\rm CRF \approx
\sqrt{CMF}$, (2) Typical interior pressure $P_{\text{typical}} \sim
g_{\rm{s}}^2$ (surface gravity squared), (3) core formation energy $E_{\rm
diff} \sim \frac{1}{10} E_{\rm grav}$ (the total gravitational energy), (4)
effective heat capacity of the mantle $C_{\rm p}\approx \left(
\frac{M_{\rm{p}}}{M_{\oplus}} \right) \cdot 7 \cdot 10^{27}$ J K$^{-1}$, and
(5) the moment of inertia $I\approx \frac{1}{3} \cdot M_{\rm{p}} \cdot
R_{\rm{p}}^2$. These scaling relations, though approximate, are handy for quick
use owing to their simplicity and lucidity, and provide insights into the
interior structures of rocky exoplanets. As examples, this model is applied to
several planets including Earth, GJ 1132b, Kepler-93b, and Kepler-20b, and made
comparison with the numerical method.


title: Variational Principle for Planetary Interiors

abstract:
  In the past few years, the number of confirmed planets has grown above 2000.
It is clear that they represent a diversity of structures not seen in our own
solar system. In addition to very detailed interior modeling, it is valuable to
have a simple analytical framework for describing planetary structures.
Variational principle is a fundamental principle in physics, entailing that a
physical system follows the trajectory which minimizes its action. It is
alternative to the differential equation formulation of a physical system.
Applying this principle to planetary interior can beautifully summarize the set
of differential equations into one, which provides us some insight into the
problem. From it, a universal mass-radius relation, an estimate of error
propagation from equation of state to mass-radius relation, and a form of
virial theorem applicable to planetary interiors are derived.


title:
Large deviation asymptotics for a random variable with L\'evy measure
  supported by $[0, 1]$

abstract:
  Asymptotics for Dickman's number theoretic function $\rho(u)$, as $u
\rightarrow \infty$, were given de Bruijn and Alladi, and later in sharper form
by Hildebrand and Tenenbaum. The perspective in these works is that of analytic
number theory. However, the function $\rho(\cdot)$ also arises as a constant
multiple of a certain probability density connected with a scale invariant
Poisson process, and we observe that Dickman asymptotics can be interpreted as
a Gaussian local limit theorem for the sum of arrivals in a tilted Poisson
process, combined with untilting.
  In this paper we exploit and extend this reasoning to obtain analogous
asymptotic formulas for a class of functions including, in addition to
Dickman's function, the densities of random variables having L\'evy measure
with support contained in $[0,1]$, subject to mild regularity assumptions.


title: Time varying axially symmetric vector random fields on the sphere

abstract:
  This paper presents a general form of the covariance matrix structure for a
vector random field that is axially symmetric and mean square continuous on the
sphere and provides a series representation for a longitudinally reversible
one. The series representation is somehow an imitator of the covariance matrix
function, and both of them have simpler forms than those proposed in the
literature in terms of the associated Legendre functions and are useful for
modeling and simulation. Also, a general form of the covariance matrix
structure is derived for a spatio-temporal vector random field that is axially
symmetric and mean square continuous over the sphere, and a series
representation is given for a longitudinally reversible one.


title: An Ultraluminous Lyman Alpha Emitter with a Blue Wing at z=6.6

abstract:
  We report the detection of the most luminous high-redshift Lyman Alpha
Emitting galaxy (LAE) yet seen, with log L(Ly alpha) = 43.9 ergs/s. The galaxy
-- COSMOS Lyman alpha 1, or COLA1 -- was detected in a search for
ultra-luminous LAEs with Hyper Suprime-Cam on the Subaru telescope. It was
confirmed to lie at z = 6.593 based on a Lyman alpha line detection obtained
from followup spectroscopy with the DEIMOS spectrograph on Keck2. COLA1 is the
first very high-redshift LAE to show a multi-component Lyman alpha line profile
with a blue wing, which suggests that it could lie in a highly ionized region
of the intergalactic medium and could have significant infall. If this
interpretation is correct, then ultra-luminous LAEs like COLA1 offer a unique
opportunity to determine the properties of the HII regions around these
galaxies which will help in understanding the ionization of the z ~ 7
intergalactic medium.


title:
Online self-disclosure and wellbeing of adolescents: A systematic
  literature review

abstract:
  The present research investigated the extent of online self-disclosure (SD)
of adolescents through a systematic decadal literature review. This review
identified three major areas of research focus, with studies categorized mainly
as: (1) factors contributing to online SD of adolescents; (2) risks and
consequences of online SD; and (3) future directions of research and practical
interventions to address the problems. A detailed examination of the variables
covered by the studies indicated that only a few aspects related to
adolescents' online SD were addressed and these variables did not receive
in-depth analysis. Some aspects of online SD received too much attention while
others received none. Based on these findings, the present research argues that
further research using sophisticated scientific research designs is needed to
understand adolescents' online SD.


title:
Information Security Strategy in Organisations: Review, Discussion and
  Future Research Directions

abstract:
  Dependence on information, including for some of the world's largest
organisations such as governments and multi-national corporations, has grown
rapidly in recent years. However, reports of information security breaches and
their associated consequences continue to indicate that attacks are still
escalating on organisations when conducting these information-based activities.
Clearly, more research is needed to better understand how organisations should
formulate strategy to secure their information. Through a thematic review of
academic security literature, we (1) analyse the antecedent conditions that
motivate the potential adoption of a comprehensive information security
strategy, (2) the current perspectives of strategy and (3) the yields and
benefits that could be enjoyed post-adoption. Our contributions include a
definition of information security strategy. We argue for a paradigm shift to
extend from internally-focussed protection of organisation-wide information
towards a strategic view that considers the inter-organisational level. Our
findings are then used to suggest future research directions.


title:
Application of Facial Reduction to $H_\infty$ State Feedback Control
  Problem

abstract:
  One often encounters numerical difficulties in solving linear matrix
inequality (LMI) problems obtained from $H_\infty$ control problems. We discuss
the reason from the viewpoint of optimization, and provide necessary and
sufficient conditions for LMI problem and its dual not to be strongly feasible.
Moreover, we interpret them in terms of control system. In this analysis,
facial reduction, which was proposed by Borwein and Wolkowicz, plays an
important role. We show that a necessary and sufficient condition closely
related to the existence of invariant zeros in the closed left-half plane in
the system, and present a way to remove the numerical difficulty with the null
vectors associated with invariant zeros in the closed left-half plane.
Numerical results show that the numerical stability is improved by applying it.


title: Strategy in a Digital World

abstract:
  Organizations are increasingly adopting digital strategies and investing
heavily in digital technologies and initiatives. However, to date, there does
not appear to be a clear understanding of digital strategies and their purpose,
which forms the motivation for this research. This research-in-progress study
aims to address this research gap by exploring 1) the various conceptions of
digital strategy, and 2) the way in which digital strategies differ from
conventional strategies, through interviews with three senior executives. We
employed thematic analysis to analyse the interview data, which resulted in the
identification of ten themes that were grouped under three theoretical
constructs. We then explored the applicability of the six dimensions of
strategy proposed by Hax (1990) in the digital context and proposed two
additional dimensions. The contribution of this study is to provide a deeper
understanding of digital strategy to support further academic research and
provide guidance to practitioners.


title:
Combining The Fogg Behavioural Model And Hook Model To Design Features
  In A Persuasive App To Improve Study Habits

abstract:
  Using technology to persuade people to behave in a certain way is an
ever-increasing field of study. The ability to persuade individuals is quite
clear in e-commerce, where individuals are persuaded to make purchasing
decisions. However, it can also be applied to other disciplines, such as
education where improving the study behaviour of students would be particularly
useful. Forming good study habits can be a challenge for university students
who have not done so in the earlier years of their education, or where the
pressures of external commitments have eroded previously good habits. We use a
combination of the Fogg Behavioural Model and the Hook model to design features
for an app as a component of a larger persuasive system to help improve three
key areas of study habits: study scheduling, class preparation and group study.
The app will be built and tested in a university setting targeting
undergraduate students.


title:
Identification of the Fractional quantum Hall edge modes by density
  oscillations

abstract:
  The neutral fermionic edge mode is essential to the non-Abelian topological
property and its experimental detection in $Z_k$ fractional quantum Hall (FQH)
state for $k > 1$. Usually, the identification of the edge modes in a finite
size system is difficult, especially near the region of the edge
reconstruction, due to mixing with the bosonic edge mode and the bulk states as
well. We study the edge-mode excitations of the Moore-Read (MR) and Read-Rezayi
(RR) states by using Jack polynomials in the truncated subspace. It is found
that the electron density, as a detector, has marked different behaviors
between the bosonic and fermionic edge modes. As an application, it helps us to
identify them near the edge reconstruction and in the RR edge spectrum. On the
other hand, we systematically study the edge excitations for the RR state,
extrapolate the edge velocities and their related coherence length and
temperature in the interferometer experiments.


title:
Testing a modified ASKAP Mark II phased array feed on the 64 m Parkes
  radio telescope

abstract:
  We present the first installation and characterization of a phased array feed
(PAF) on the 64 m Parkes radio telescope. The combined system operates best
between 0.8 GHz and 1.74 GHz where the beamformed noise temperature is between
45 K and 60 K, the aperture efficiency ranges from 70% to 80%, and the
effective field of view is 1.4 deg$^2$ at 1310 MHz. After a 6-month trial
observing program at Parkes, the PAF will be installed on the 100 m antenna at
Effelsberg. This is the first time a PAF has been installed on a large
single-antenna radio telescope and made available to astronomers.


title:
IT Managers' Perception and Response to Digital Disruption: An
  Exploratory Study

abstract:
  Digital disruption introduces technology-enabled changes at a pace and scale
that fundamentally shifts established ways in which we live and work. Given the
impact of digital disruption can span the individual, organisational, industry
and societal levels, it has received growing attention in Information Systems.
A less researched area of digital disruption, however, is the perspective of IT
managers in organisations. This paper draws on i) situational awareness theory
to identify IT managers' perceptions of digital disruption, and ii) disruptive
innovation theory to identify IT managers' responses to digital disruption. A
case study of senior IT managers in an Australian university identifies that IT
managers perceive digital disruption from the technological, learning and
sense-making perspectives. IT managers' first-order responses to digital
disruption were shown to address resource, process and value-based issues while
second-order responses focused on the need to build dynamic capabilities in
order to be prepared for future digital disruption.


title:
Chern number in Ising models with spatially modulated real and complex
  fields

abstract:
  We study an one-dimensional transverse field Ising model with additional
periodically modulated real and complex fields. It is shown that both models
can be mapped on a pseudo spin system in the k space in the aid of an extended
Bogoliubov transformation. This allows us to introduce the geometric quantity,
the Chern number, to identify the nature of quantum phases. Based on the exact
solution, we find that the spatially modulated real and complex fields
rearrange the phase boundaries from that of the ordinary Ising model, which can
be characterized by the Chern numbers defined in the context of Dirac and
biorthonormal inner products, respectively.


title:
Spin-Orbit Interactions and the Nematicity Observed in the Fe-Based
  Superconductors

abstract:
  High-resolution angle-resolved photoelectron spectroscopy is used to examine
the electronic band structure of FeTe$_{0.5}$Se$_{0.5}$ near the Brillouin zone
center. A consistent separation of the $\alpha_{1}$ and $\alpha_{2}$ bands is
observed with little $k_{z}$ dependence of the $\alpha_{1}$ band.
First-principles calculations for bulk and thin films demonstrate that the
antiferromagnetic coupling between the Fe atoms and hybridization-induced
spin-orbit effects lifts the degeneracy of the Fe $d_{xz}$ and $d_{yz}$
orbitals at the zone center leading to orbital ordering. These experimental and
computational results provide a natural microscopic basis for the nematicity
observed in the Fe-based superconductors.


title:
Defining the optimal level of business benefits within IS/IT projects:
  Insights from benefit identification practices adopted in an IT Service
  Management (ITSM) project

abstract:
  The popularity of benefit realization management (BRM) in today's IT-enabled
world is fast gaining traction within IT organisations around the world.
However, there appears to be limited attention paid to the intra-organisational
practice by which benefits are identified. The purpose of this paper is
twofold: firstly, to describe and define a practice approach to the
identification of benefits that exploits a number of benefit identification
methods in an effort to more comprehensively identify IS/IT related benefits
that reflect the ongoing organisational investment. Secondly, to underline the
importance of this benefit identification process in the context of IT service
management (ITSM). This is achieved through a case study of an information
technology infrastructure library (ITIL) implementation in a multi-national
organization. The case study exposes a pragmatic practice approach of
customising such implementations in an effort to achieve a cost effective
implementation of IT services that reflects the context and requirements of
that specific organisation.


title:
Logistic Models of Fractal Dimension Growth for Spatio-Temporal Dynamics
  of Urban Morphology

abstract:
  Urban form and growth can be described with fractal dimension, which is a
measurement of space filling of urban evolution. Based on empirical analyses, a
discovery is made that the time series of fractal dimension of urban form can
be treated as a sigmoid function of time. Among various sigmoid functions, the
logistic function is the most probable selection. However, how to use the model
of fractal dimension growth to explain and predict urban growth is a pending
problem remaining to be solved. This paper is devoted to modeling fractal
dimension evolution of different types of cities. A interesting discovery is as
follows: for the cities in developed countries such as UK, USA and Israel, the
comparable fractal dimension values of a city's morphology in different years
can be fitted to the logistic function; while for the cities in developing
countries such as China, the fractal dimension data of urban form can be fitted
to a quadratic logistic function. A generalized logistic function is thus
proposed to model fractal dimension growth of urban form. The logistic model
can also be employed to characterize the change of the dimensions of
multifractals. The generalized logistic models can be used to predict the
missing values of fractal dimension, to estimate the growth rate of the
dimension, and thus to reveal the spatio-temporal process and pattern of a
city's growth. Especially, the models lay a foundation for researching the
correlation between urban form and urbanization and for developing the theory
of spatial replacement dynamics.


title:
Firm Growth and Innovation in the ERP Industry: A Systems Thinking
  Approach

abstract:
  Achievement and sustenance of growth are essential themes in organizational
literature. In our paper, we develop models using systems thinking approach to
understand how firms achieve and sustain growth in a technology-intensive
product domain. We augment these to explain the possible impact of a disruptive
technological innovation. We use enterprise software industry as the context
where SAP has been acknowledged as the market leader. We find that product
differentiation and learning effects helped SAP establish itself, and this
growth was further sustained through networks and complementors. Introducing
cloud computing as the disruptive innovation, we explain its impact on a firm.
Analysis reveals that for the next wave of growth to occur, and to tap into
newer markets, it would be imperative for SAP to create attractive cloud based
offerings. We also discuss how the model can be enhanced by considering
competitor dynamics.


title:
A Conceptual Framework for Accountability in Cloud Computing Service
  Provision

abstract:
  This paper uses a comprehensive review of the academic and professional
literature in relation to accountability in the area of cloud computing service
provision. It identifies four key conceptual factors that are necessary for an
organisation to be considered as accountable. The four factors were found to
be: responsibility, assurance, transparency and remediation. A key finding of
the paper is that in order to be considered as an accountable cloud service
provider, all four factors need to be implemented and be demonstrable by the
organisation.


title:
Disruptive Transformation of Enterprise Supply Chain Performance through
  Strategic Technology-enabled Networking to Improve Business Value

abstract:
  In a dynamically changing world, businesses must transform themselves to
survive. Although the necessity for change may be apparent; how to change is
not. Learning from the experiences of successful pioneers in a core business
function is useful. Procurement is essential for all organisations. It is how
organisations acquire assets and inputs including facilities, materials and
people. Traditionally, the business objective from procurement was to increase
availability and reduce costs. Subsequently, the objective became more
tactical. Leading procurement practice today is disruptive; beyond cost to
creating value. The strategy for market leaders has also transformed; from
competition to collaboration. Technology-enabled business networks are now
driving business disruption globally. Through a rigorous field study of two
world-class pioneering corporations, this paper explores how disruption is
transforming Enterprise Supply Chains. Lessons, contributions and their
implications for current IS theory and practice, are discussed.


title:
Does Broadband Connectivity and Social networking sites build and
  maintain social capital in rural communities?

abstract:
  Broadband internet access is a major enabling technology for building social
capital (SC) by better connecting rural and regional communities which are
often geographically dispersed both locally nationally and internationally. The
main objectives of this paper were determine to what extent Social Networking
Sites (SNS) can build SC for households in a rural and regional context of
rural household adoption and use of broadband internet. A large scale survey of
households was used to collect empirical data regarding household adoption and
use of Broadband internet services including SNSs and their contribution to
building SC in rural communities. The results of this study confirmed that SNSs
would appear to build SC two high level dimensions bonding and bridging for
households in rural communities such as Western Downs Region. Moreover SNS
users would appear to have significantly higher levels of SC than Non-SNS users
in rural communities.


title:
Using stories to bridge the chasm between perspectives: How metaphors
  and genres are used to share meaning

abstract:
  Natural language, although complex in structure, contains considerable
detail. All instances of language serve the purpose of making sense of
experience and the intent of actors. Language conveys actor's personal
reference to goals, responsibility, and values. In this paper we consider how
actors from distinct perspectives communicate when they have share common
goals. We have observed the planning of a community and cultural event where
actors are variously responsible for management and for artistic merit.
  Specifically, we consider actor's use of language as a tool to span
perspectives and how functional discourse analysis tools and techniques enable
a deeper interpretive understanding of the layers of discourse when derived
from a rich context. We will also illustrate patterns we have found in the use
of discourse and actor's ability to bridge the reasoning and logical gap
between distinct perspectives through actor's reference to metaphors and
genres.


title: Quantitative Analysis of Desirability in User Experience

abstract:
  The multi-dimensional nature of user experience warrants rigorous assessment
of the interactive experience in systems. User experience assessments are based
on product evaluations and subsequent analysis of the collected data using
quantitative and qualitative techniques. The quality of user experience
assessments are dependent on the effectiveness of the techniques deployed. This
paper presents the results of a quantitative analysis of desirability aspects
of the user experience in a comparative product evaluation study. The data
collection was conducted using 118 item Microsoft Product Reaction Cards (PRC)
tool followed by data analysis based on the Surface Measure of Overall
Performance (SMOP) approach. The results of this study suggest that the
incorporation of SMOP as an approach for PRC data analysis derive conclusive
evidence of desirability in user experience. The significance of the paper is
that it presents a novel analysis method incorporating product reaction cards
and surface measure of overall performance approach for an effective
quantitative analysis which can be used in academic research and industrial
practice.


title: A probabilistic proof of a binomial identity

abstract:
  We give an elementary probabilistic proof of a binomial identity. The proof
is obtained by computing the probability of a certain event in two different
ways, yielding two different expressions for the same quantity.


title:
An SME's Adoption of a Cloud Based Integrated Management System (IMS)
  When Certifying Against Management System Standards (MSS)

abstract:
  This case study introduces a four step approach used by a Singapore small and
medium enterprise (SME) in implementing a cloud computing based integrated
management system (IMS) to meet the ISO 9001, ISO 14001, and OHSAS 18001
certification requirements. The objectives of this case study are to study: (1)
the challenges encountered by an SME during the IMS integration process at each
of the four levels of integration (2) the extent which Frugal IT Innovation and
Technology Acceptance Model (TAM3) concepts apply to our four step approach.
The four step approach was assessed against a framework of four integration
levels of the management systems (MS), and also the applicability of two IS
theories (Frugal IT Innovation and TAM3). Data was collected via: (1) direct
observations (2) participant observations; (3) interviews with key personnel
involved in the project; and (4) analysis of documents pertaining to the
project. This case study provides an exemplary model on using IS theories and
public cloud technologies to develop an effective IMS that other SMEs can learn
from.


title: An Analysis of Personal Information Privacy Concerns Using Q-Methodology

abstract:
  Information privacy has gained increased attention in recent years. This
paper focuses on a particular aspect of privacy, i.e., personal information
privacy. In this paper a conceptual framework is developed based Westin's
theory of Personal Information Privacy (PIP). Concourse theory and
Q-methodology was used alongside the literature and the New Zealand Privacy Act
1993 to develop a Q-sort questionnaire. The resulting 29 statements were then
sorted by 12 students (majoring in IS Security). The results indicate that for
some, privacy priorities may be stable across contexts, and for others this
differs, suggesting that current views of privacy (e.g. Westin's theory) may
need revising for the modern digital age. The Q-sort methodology also
identified three types, each representing distinct collective perspectives on
personal information privacy. These types are discussed along with implications
and suggestions for future research.


title: Enhancing Public Service Delivery through Organisational Modeling

abstract:
  Government organisations utilise a Citizen's Charter in order to furnish the
public with comprehensive details of their service offerings that defines how
their overall organisational goals are achieved. Studies on the implementation
of Citizen's Charter in developing countries indicated that important social
factors were not considered. Reviewed literatures indicated that social factors
could accelerate service delivery with the use of goal-oriented modelling (such
as i* organisational modeling) as it represent conditions expected from social
actors and their social dependencies. By modelling role dependencies among
actors carrying out services in a business unit and applying vulnerability and
criticality metrics, problem service areas were identified using the Citizen's
Charter as a source of these methodologies. Improvements in these problem
service areas were based on vulnerability and criticality levels of their
corresponding actors. Recommendations to address these service areas include
monitoring of key performance indicators of actors and task delegation when
necessary.


title: Applying Adapted Big Five Teamwork Theory to Agile Software Development

abstract:
  Teamwork is a central tenet of agile software development and various
teamwork theories partially explain teamwork in that context. Big Five teamwork
theory is one of the most influential teamwork theories, but prior research
shows that the team leadership concept in this theory it is not applicable to
agile software development. This paper applies an adapted form of Big Five
teamwork theory to cases of agile software development. Three independent cases
were drawn from a single organisation. This ensured a measure of control over
contextual factors affecting the teamwork. The findings show that the adapted
form of Big Five teamwork theory, including a shared team leadership concept,
is fully applicable to some forms of agile software development, but not all.
For practitioners, insights as to which agile practices support teamwork are
provided.


title:
Improving pathology reports using business intelligence techniques: An
  experimental study

abstract:
  Health professionals use pathology reports to monitor and manage a patient's
health. Typically, pathologists diagnose patients' conditions and produce these
reports which are then used as reference by clinicians and eventually shared
with the patient. Pathology reports are difficult to interpret as the reports
are written using complex medical terminology. As patients only see their
doctors for a limited time, the complexity of report content and the manner in
which the information is presented in the reports may hinder patients'
understanding of their medical condition and prognosis. The objective of this
study was to compare patient comprehension of results from two
pathology-reporting styles: the traditional format in current widespread use
and new style developed using techniques common in business intelligence system
(BI) development. The study found that the reports prepared using a "BI style"
improve experimental subject's understanding and satisfaction with the reports.


title: Interdisciplinary Translation of Comparative Visualization

abstract:
  Spatial visualisation skills and interpretations are critical in the design
professions, but traditionally difficult to effectively teach. Visualization
and multimedia presentation studies show positive improvements in learner
outcomes for specific learning domains. But the development and translation of
a comparative visualization pedagogy between disciplines is poorly understood.
This research seeks to identify an approach to developing comparable multimodal
and interactive visualizations and attendant student reflections for curriculum
designers in courses that can utilize visualizations and manipulations. Results
from previous use of comparative multimodal visualization pedagogy in a
multimedia 3D modelling class are used as a guide to translation of pedagogy to
architecture design. The focus is how to guide the use of comparative
multimodal visualizations through media properties, lesson sequencing, and
reflection to inform effective instruction and learning.


title:
Exact Post-Selection Inference for Changepoint Detection and Other
  Generalized Lasso Problems

abstract:
  We study tools for inference conditioned on model selection events that are
defined by the generalized lasso regularization path. The generalized lasso
estimate is given by the solution of a penalized least squares regression
problem, where the penalty is the l1 norm of a matrix D times the coefficient
vector. The generalized lasso path collects these estimates for a range of
penalty parameter ({\lambda}) values. Leveraging a sequential characterization
of this path from Tibshirani & Taylor (2011), and recent advances in
post-selection inference from Lee et al. (2016), Tibshirani et al. (2016), we
develop exact hypothesis tests and confidence intervals for linear contrasts of
the underlying mean vector, conditioned on any model selection event along the
generalized lasso path (assuming Gaussian errors in the observations). By
inspecting specific choices of D, we obtain post-selection tests and confidence
intervals for specific cases of generalized lasso estimates, such as the fused
lasso, trend filtering, and the graph fused lasso. In the fused lasso case, the
underlying coordinates of the mean are assigned a linear ordering, and our
framework allows us to test selectively chosen breakpoints or changepoints in
these mean coordinates. This is an interesting and well-studied problem with
broad applications, our framework applied to the trend filtering and graph
fused lasso serves several applications as well. Aside from the development of
selective inference tools, we describe several practical aspects of our methods
such as valid post-processing of generalized estimates before performing
inference in order to improve power, and problem-specific visualization aids
that may be given to the data analyst for he/she to choose linear contrasts to
be tested. Many examples, both from simulated and real data sources, are
presented to examine the empirical properties of our inference methods.


title:
Doctoral Consortium - Australasian Conference on Information Systems
  (ACIS) 2015

abstract:
  This submission contains all publications from the ACIS 2015 Doctoral
Consortium held in Adelaide, Australia from November 30 - December 1, 2015.


title: Characterization of base roughness for granular chute flows

abstract:
  Base roughness plays an important role to the dynamics of granular flows but
is yet poorly understood due to the difficulty of its quantification. For a
bumpy base made by spheres, at least two factors should be considered to
characterize its geometric roughness, namely the size ratio of base- to
flow-particles and the packing of base particles. In this paper, we propose a
definition of base roughness, Ra, which is a function of both the size ratio
and the packing arrangement of base particles. The function is generalized for
random and regular packing of multi-layered spheres, where the range of
possible values of Ra is studied, along with the optimal values to create
maximum base roughness. The new definition is applied to granular flows down
chute in both two- and three-dimensional configurations. It is proven to be a
good indicator of slip condi- tion, and a transition occurs from slip to
non-slip condition as Ra increases. Critical values of Ra are identified for
the construction of a non-slip base. The effects of contact parameters on base
velocity are studied, and it is shown that while the coefficient of friction is
less influential, normal damping has more profound effect on base velocity at
lower values of Ra. The application of present definition to other base
geometries is also discussed.


title: Ultrafast Band Structure Control of a Two-Dimensional Heterostructure

abstract:
  The electronic structure of two-dimensional (2D) semiconductors can be
significantly altered by screening effects, either from free charge carriers in
the material itself, or by environmental screening from the surrounding medium.
The physical properties of 2D semiconductors placed in a heterostructure with
other 2D materials are therefore governed by a complex interplay of both intra-
and inter-layer interactions. Here, using time- and angle-resolved
photoemission, we are able to isolate both the layer-resolved band structure
and, more importantly, the transient band structure evolution of a model 2D
heterostructure formed of a single layer of MoS$_2$ on graphene. Our results
reveal a pronounced renormalization of the quasiparticle gap of the MoS$_2$
layer. Following optical excitation, the band gap is reduced by up to
$\sim\!$400 meV on femtosecond timescales due to a persistence of strong
electronic interactions despite the environmental screening by the $n$-doped
graphene. This points to a large degree of tuneability of both the electronic
structure and electron dynamics for 2D semiconductors embedded in a van der
Waals-bonded heterostructure.


title:
Human Attention in Visual Question Answering: Do Humans and Deep
  Networks Look at the Same Regions?

abstract:
  We conduct large-scale studies on `human attention' in Visual Question
Answering (VQA) to understand where humans choose to look to answer questions
about images. We design and test multiple game-inspired novel
attention-annotation interfaces that require the subject to sharpen regions of
a blurred image to answer a question. Thus, we introduce the VQA-HAT (Human
ATtention) dataset. We evaluate attention maps generated by state-of-the-art
VQA models against human attention both qualitatively (via visualizations) and
quantitatively (via rank-order correlation). Overall, our experiments show that
current attention models in VQA do not seem to be looking at the same regions
as humans.


title: Sample covariance matrices of heavy-tailed distributions

abstract:
  Let $p>2$, $B\geq 1$, $N\geq n$ and let $X$ be a centered $n$-dimensional
random vector with the identity covariance matrix such that $\sup\limits_{a\in
S^{n-1}}{\mathrm E}|\langle X,a\rangle|^p\leq B$. Further, let
$X_1,X_2,\dots,X_N$ be independent copies of $X$, and
$\Sigma_N:=\frac{1}{N}\sum_{i=1}^N X_i {X_i}^T$ be the sample covariance
matrix. We prove that $$K^{-1}\|\Sigma_N-I_n\|_{2\to
2}\leq\frac{1}{N}\max\limits_{i\leq N}\|X_i\|^2
+\Bigl(\frac{n}{N}\Bigr)^{1-2/p}\log^4\frac{N}{n}+\Bigl(\frac{n}{N}\Bigr)^{1-2/\min(p,4)}$$
with probability at least $1-\frac{1}{n}$, where $K>0$ depends only on $B$ and
$p$. In particular, for all $p>4$ we obtain a quantitative Bai-Yin type
theorem.


title: Universal Correspondence Network

abstract:
  We present a deep learning framework for accurate visual correspondences and
demonstrate its effectiveness for both geometric and semantic matching,
spanning across rigid motions to intra-class shape or appearance variations. In
contrast to previous CNN-based approaches that optimize a surrogate patch
similarity objective, we use deep metric learning to directly learn a feature
space that preserves either geometric or semantic similarity. Our fully
convolutional architecture, along with a novel correspondence contrastive loss
allows faster training by effective reuse of computations, accurate gradient
computation through the use of thousands of examples per image pair and faster
testing with $O(n)$ feed forward passes for $n$ keypoints, instead of $O(n^2)$
for typical patch similarity methods. We propose a convolutional spatial
transformer to mimic patch normalization in traditional features like SIFT,
which is shown to dramatically boost accuracy for semantic correspondences
across intra-class shape variations. Extensive experiments on KITTI, PASCAL,
and CUB-2011 datasets demonstrate the significant advantages of our features
over prior works that use either hand-constructed or learned features.


title: Coupled Leidenfrost States as a Monodisperse Granular Clock

abstract:
  Using an event-driven molecular dynamics simulation, we show that simple
monodisperse granular beads confined in coupled columns may oscillate as a new
type of granular clock. To trigger this oscillation, the system needs to be
driven against gravity into a density-inverted state, with a high-density
clustering phase supported from below by a gas-like low-density phase
(Leidenfrost effect) in each column. Our analysis reveals that the
density-inverted structure and the relaxation dynamics between the phases can
amplify any small asymmetry between the columns, and lead to a giant
oscillation. The oscillation occurs only for an intermediate range of the
coupling strength, and the corresponding phase diagram can be universally
described with a characteristic height of the density-inverted structure. A
minimal two-phase model is proposed and linear stability analysis shows that
the triggering mechanism of the oscillation can be explained as a switchable
two-parameter Hopf bifurcation. Numerical solutions of the model also reproduce
similar oscillatory dynamics to the simulation results.


title:
Efficient numerical methods for searching equillibriums in large
  transport networks

abstract:
  We propose new variational principles for traffic assignment problems. So to
find equillibrium we have to solve large-scale convex optimization problem of
special type. We propose some kind of "algebra" on different models and
corresponding numerical algorithms that allows us to combine the optimal method
from the basis ones and predescribed operations on methods.


title: Sub-Story Detection in Twitter with Hierarchical Dirichlet Processes

abstract:
  Social media has now become the de facto information source on real world
events. The challenge, however, due to the high volume and velocity nature of
social media streams, is in how to follow all posts pertaining to a given event
over time, a task referred to as story detection. Moreover, there are often
several different stories pertaining to a given event, which we refer to as
sub-stories and the corresponding task of their automatic detection as
sub-story detection. This paper proposes hierarchical Dirichlet processes
(HDP), a probabilistic topic model, as an effective method for automatic
sub-story detection. HDP can learn sub-topics associated with sub-stories which
enables it to handle subtle variations in sub-stories. It is compared with
state- of-the-art story detection approaches based on locality sensitive
hashing and spectral clustering. We demonstrate the superior performance of HDP
for sub-story detection on real world Twitter data sets using various
evaluation measures. The ability of HDP to learn sub-topics helps it to recall
the sub- stories with high precision. Another contribution of this paper is in
demonstrating that the conversational structures within the Twitter stream can
be used to improve sub-story detection performance significantly.


title: Analytic Tableaux for Justification Logics

abstract:
  In this paper we present analytic tableau proof systems for various
justification logics. We show that the tableau systems are sound and complete
with respect to Mkrtychev models. In order to prove the completeness of the
tableaux, we give a syntactic proof of cut elimination. We also show the
subformula property for our tableaux, and prove the decidability of
justification logics for finite constant specifications.


title: On groups $G_{n}^{k}$, braids and Brunnian braids

abstract:
  In \cite{Manturov} the second author defined the $k$-free braid group with
$n$ strands $G_{n}^{k}$. These groups appear naturally as groups describing
dynamical systems of $n$ particles in some "general position". Moreover, in
\cite{ManturovNikonov} the second author and I.M.Nikonov showed that
$G_{n}^{k}$ is closely related classical braids. The authors showed that there
are homomorphisms from the pure braids group on $n$ strands to $G_{n}^{3}$ and
$G_{n}^{4}$ and they defined homomorphisms from $G_{n}^{k}$ to the free product
of $\mathbb{Z}_{2}$. That is, there are invariants for pure free braids by
$G_{n}^{3}$ and $G_{n}^{4}$.
  On the other hand in \cite{FedoseevManturov} D.A.Fedoseev and the second
author studied classical braids with addition structures: parity and points on
each strands. The authors showed that the parity, which is an abstract
structure, has geometric meaning -- points on strands. In \cite{Kim}, the first
author studied $G_{n}^{2}$ with parity and points. the author construct a
homomorphism from $G_{n+1}^{2}$ to the group $G_{n}^{2}$ with parity.
  In the present paper, we investigate the groups $G_{n}^{3}$ and extract new
powerful invariants of classical braids from $G_{n}^{3}$. In particular, these
invariants allow one to distinguish the non-triviality of Brunnian braids.


title: Homology graph of real arrangements and monodromy of Milnor Fiber

abstract:
  We study the first homology group of the Milnor fiber of sharp arrangements
in the real projective plane. Our work relies on the minimal Salvetti complex
of the deconing arrangement and its boundary map. We describe an algorithm
which computes possible eigenvalues of the first monodromy operator. We prove
that, if a condition on some intersection points of lines is satisfied, then
the only possible non trivial eigenvalues are cubic roots of the unity.
Moreover we give sufficient conditions for just eigenvalues of order 3 or 4 to
appear in cases in which this condition is not satisfied.


title: Flexibility of short DNA helices under mechanical stretching

abstract:
  The flexibility of short DNA fragments is studied by a Hamiltonian model
which treats the inter-strand and intra-strand forces at the level of the base
pair. The elastic response of a set of homogeneous helices to externally
applied forces is obtained by computing the average bending angles between
adjacent base pairs along the molecule axis. The ensemble averages are
performed over a room temperature equilibrium distribution of base pair
separations and bending fluctuations. The analysis of the end-to-end distances
and persistence lengths shows that even short sequences with less than $100$
base pairs maintain a significant bendability ascribed to thermal fluctuational
effects and kinks with large bending angles. The discrepancies between the
outcomes of the discrete model and those of the worm-like-chain model are
examined pointing out the inadequacy of the latter on short length scales.

categories: q-bio.BM cond-mat.soft physics.bio-ph physics.chem-ph


title: Facets and volume of Gorenstein Fano polytopes

abstract:
  It is known that every integral convex polytope is unimodularly equivalent to
a face of some Gorenstein Fano polytope. It is then reasonable to ask whether
every normal polytope is unimodularly equivalent to a face of some normal
Gorenstein Fano polytope. In the present paper, it is shown that, by giving new
classes of normal Gorenstein Fano polytopes, each order polytope as well as
each chain polytope of dimension $d$ is unimodularly equivalent to a facet of
some normal Gorenstein Fano polytopes of dimension $d + 1$. Furthermore,
investigation on combinatorial properties, especially, Ehrhart polynomials and
volume of these new polytopes will be achieved. Finally, some curious examples
of Gorenstein Fano polytopes will be discovered.


title:
Rich and Poor Cities in Europe. Urban Scaling to Mapping European
  Economic Convergence

abstract:
  Recent advances in the urban science make broad use of the notion of scaling.
We focus here on the important scaling relationship between the gross
metropolitan product (GMP) of a city and its population (pop). It has been
demonstrated that GMP $\propto$ Y pop $^{\beta}$ with $\beta$ always greater
than 1 and close to 1.2. This fundamental finding highlights a universal rule
that holds across countries and cultures and might explain the very nature of
cities. However, in an increasingly connected world, the hypothesis that the
economy of a city solely depends on its population might be questionable. Using
data for 248 cities in the European Union between 2005 and 2010, we found a
double GMP/pop scaling regime. For West EU cities, $\beta$ = 1 over the whole
the period, while for post-communist cities $\beta >$1 and increases from
$\sim$1.2 to $\sim$1.4. The evolution of the scaling exponent describes the
convergence of post-communist European cities to open and liberal economies. We
propose a simple model of economic convergence in which, under stable political
conditions, a linear GMP/pop scaling is expected for all cities. The results
suggest that the GMP/pop super-linear scaling represents a phase of economic
growth rather than a steady, universal urban feature. The results also suggest
that relationships between cities are embedded in their political and economic
context and cannot be neglected in explanations of cities, urbanization and
urban economics.


title: Word Sense Disambiguation using a Bidirectional LSTM

abstract:
  In this paper we present a clean, yet effective, model for word sense
disambiguation. Our approach leverage a bidirectional long short-term memory
network which is shared between all words. This enables the model to share
statistical strength and to scale well with vocabulary size. The model is
trained end-to-end, directly from the raw text to sense labels, and makes
effective use of word order. We evaluate our approach on two standard datasets,
using identical hyperparameter settings, which are in turn tuned on a third set
of held out data. We employ no external resources (e.g. knowledge graphs,
part-of-speech tagging, etc), language specific features, or hand crafted
rules, but still achieve statistically equivalent results to the best
state-of-the-art systems, that employ no such limitations.


title:
A framework for detecting fraudulent activities in edo state tax
  collection system using investigative data mining

abstract:
  The Inland Revenue Services is overwhelmed with gigabyte of disk capacity
containing data about tax payers in the state. The data stored on the database
increases in size at an alarming rate. This has resulted in a data rich but
information poor situation where there is a widening gap between the explosive
growth of data and its types, and the ability to analyze and interpret it
effectively, hence the need for a new generation of automated and intelligent
tools and techniques known as investigative data mining, to look for patterns
in data. These patterns can lead to new insights, competitive advantages for
business, and tangible benefits for the State Revenue services. This research
work focuses on designing effective fraud detection and deterring architecture
using investigative data mining technique. The proposed system architecture is
designed to reason using Artificial Neural Network and Machine learning
algorithm in order to detect and deter fraudulent activities. We recommend that
the architectural framework be developed using Object Oriented Programming and
Agent Oriented Programming Languages.


title:
The self-consistent charge density functional tight-binding (DFTB)
  theory study of carbon adatoms using tuned Hubbard U parameters

abstract:
  The self-consistent charge density functional tight-binding (DFTB) theory is
a useful tool for realizing the electronic structures of large molecular
complex systems. In this study, we analyze the electronic structure of C61,
formed by fullerene C60 with a carbon adatom, using the fully localized limit
and pseudo self-interaction correction methods of DFTB to adjust the Hubbard U
parameter (DFTB+U). The results show that both the methods used to adjust U can
significantly reduce the molecular orbital energy of occupied states localized
on the defect carbon atom and improve the gap between highest occupied
molecular orbital(HOMO) and lowest unoccupied molecular orbital(LUMO) of C61.
This work will provide a methodological reference point for future DFTB
calculations of the electronic structures of carbon materials.


title: Universal Routing in Multi-hop Radio Networks

abstract:
  In this article we introduce a new model to study stability in multi-hop
wireless networks in the framework of adversarial queueing. In such a model, a
routing protocol consists of three components: a transmission policy, a
scheduling policy to select the packet to transmit form a set of packets parked
at a node, and a hearing control mechanism to coordinate transmissions with
scheduling. For such a setting, we propose a definition of universal stability
that takes into account not only the scheduling policies (as in the standard
wireline adversarial model), but also the transmission policies. First, we show
that any scheduling policy that is unstable in the classical wireline
adversarial model remains unstable in the multi-hop radio network model, even
in scenarios free of inter- ferences. Then, we show that both SIS and LIS (two
well-known universally stable scheduling policies in the wireline adversarial
model) remain stable in the multi-hop radio network model, provided a proactive
hearing control is used. In contrast, such scheduling policies turn out to be
unstable when using a reactive hearing control. However, the scheduling policy
LIS can be enforced to be universally stable provided ties are resolved in a
permanent manner. Such a situation doesn't hold in the case of SIS, which
remains unstable regardless of how ties are resolved. Furthermore, for some
transmission policies which we call regular, we also show that all scheduling
policies that are universally stable when using proactive hearing control
(which include SIS and LIS) remain universally stable when using reactive
hearing control.


title: Differentially Private Random Decision Forests using Smooth Sensitivity

abstract:
  We propose a new differentially-private decision forest algorithm that
minimizes both the number of queries required, and the sensitivity of those
queries. To do so, we build an ensemble of random decision trees that avoids
querying the private data except to find the majority class label in the leaf
nodes. Rather than using a count query to return the class counts like the
current state-of-the-art, we use the Exponential Mechanism to only output the
class label itself. This drastically reduces the sensitivity of the query --
often by several orders of magnitude -- which in turn reduces the amount of
noise that must be added to preserve privacy. Our improved sensitivity is
achieved by using "smooth sensitivity", which takes into account the specific
data used in the query rather than assuming the worst-case scenario. We also
extend work done on the optimal depth of random decision trees to handle
continuous features, not just discrete features. This, along with several other
improvements, allows us to create a differentially private decision forest with
substantially higher predictive power than the current state-of-the-art.


title:
Scalar products of Bethe vectors in models with $\mathfrak{gl}(2|1)$
  symmetry 2. Determinant representation

abstract:
  We study integrable models with $\mathfrak{gl}(2|1)$ symmetry and solvable by
nested algebraic Bethe ansatz. We obtain a determinant representation for
scalar products of Bethe vectors, when the Bethe parameters obey some relations
weaker than the Bethe equations. This representation allows us to find the
norms of on-shell Bethe vectors and obtain determinant formulas for form
factors of the diagonal entries of the monodromy matrix.


title:
Monte Carlo simulation of a very high resolution thermal neutron
  detector composed of glass scintillator microfibers

abstract:
  In order to develop a high spatial resolution (micron level) thermal neutron
detector, a detector assembly composed of cerium doped lithium glass
microfibers, each with a diameter of 1\,$\mu$m, is proposed, where the neutron
absorption location is reconstructed from the observed charged particle
products that result from neutron absorption. To suppress the cross talk of the
scintillation light, each scintillating fiber is surrounded by air-filled glass
capillaries with the same diameter as the fiber. This pattern is repeated to
form a bulk microfiber detector. On one end, the surface of the detector is
painted with a thin optical reflector to increase the light collection
efficiency at the other end. Then the scintillation light emitted by any
neutron interaction is transmitted to one end, magnified, and recorded by an
intensified CCD camera. A simulation based on the Geant4 toolkit was developed
to model this detector. All the relevant physics processes including neutron
interaction, scintillation, and optical boundary behaviors are si\-mulated.
This simulation was first validated through measurements of neutron response
from lithium glass cylinders. With good expected light collection, an algorithm
based upon the features inherent to alpha and triton particle tracks is
proposed to reconstruct the neutron reaction position in the glass fiber array.
Given a 1\,$\mu$m fiber diameter and 0.1\,mm detector thickness, the neutron
spatial resolution is expected to reach $\sigma\sim 1\, \mu$m with a Gaussian
fit in each lateral dimension. The detection efficiency was estimated to be
3.7\% for a glass fiber assembly with thickness of 0.1\,mm. When the detector
thickness increases from 0.1\,mm to 1\,mm, the position resolution is not
expected to vary much, while the detection efficiency is expected to increase
by about a factor of ten.


title:
On wave operators for Schr\"odinger operators with threshold
  singuralities in three dimensions

abstract:
  We show that wave operators for three dimensional Schr\"odinger operators
$H=-\Delta + V$ with threshold singularities are bounded in $L^1({\mathbb
R}^3)$ if and only if zero energy resonances are absent from $H$ and the
existence of zero energy eigenfunctions does not destroy the $L^1$-boundedness
of wave operators for $H$ with the regular threshold behavior. We also show in
this case that they are bounded in $L^p({\mathbb R}^3)$ for all $1\leq p \leq
\infty$ if all zero energy eigenfunctions $\phi(x)$ have vanishing first three
moments: $\int_{{\mathbb R}^3} x^\alpha V(x)\phi(x)dx=0$, $|\alpha|=0,1,2$.


title: The asymptotics of the Touchard polynomials: a uniform approximation

abstract:
  The asymptotic expansion of the Touchard polynomials $T_n(z)$ (also known as
the exponential polynomials) for large $n$ and complex values of the variable
$z$, where $|z|$ may be finite or allowed to be large like $O(n)$, has been
recently considered in \cite{P1}. When $z=-x$ is negative, it is found that
there is a coalesence of two contributory saddle points when $n/x=1/e$. Here we
determine the expansion when $n$ and $x$ satisfy this condition and also a
uniform two-term approximation involving the Airy function in the neighbourhood
of this value. Numerical results are given to illustrate the accuracy of the
asymptotic approximations obtained.


title:
Phenomenological MSSM interpretation of CMS searches in pp collisions at
  sqrt(s) = 7 and 8 TeV

abstract:
  Searches for new physics by the CMS collaboration are interpreted in the
framework of the phenomenological minimal supersymmetric standard model
(pMSSM). The data samples used in this study were collected at sqrt(s) = 7 and
8 TeV and have integrated luminosities of 5.0 and 19.5 inverse-femtobarns,
respectively. A global Bayesian analysis is performed, incorporating results
from a broad range of CMS supersymmetry searches, as well as constraints from
other experiments. Because the pMSSM incorporates several well-motivated
assumptions that reduce the 120 parameters of the MSSM to just 19 parameters
defined at the electroweak scale, it is possible to assess the results of the
study in a relatively straightforward way. Approximately half of the model
points in a potentially accessible subspace of the pMSSM are excluded,
including all pMSSM model points with a gluino mass below 500 GeV, as well as
models with a squark mass less than 300 GeV. Models with chargino and
neutralino masses below 200 GeV are disfavored, but no mass range of model
points can be ruled out based on the analyses considered. The nonexcluded
regions in the pMSSM parameter space are characterized in terms of physical
processes and key observables, and implications for future searches are
discussed.


title:
Alternative Technique to Asymmetry Analysis-Based Overlapping for Foot
  Ulcer Examination: Scalable Scanning

abstract:
  Asymmetry analysis based on the overlapping of thermal images proved able to
detect inflammation and, predict foot ulceration. This technique involves three
main steps: segmentation, geometric transformation, and overlapping. However,
the overlapping technique, which consists of subtracting the intensity levels
of the right foot from those of the left foot, can also detect false abnormal
areas if the projections of the left and right feet are not the same. In this
paper, we present an alternative technique to asymmetry analysis-based
overlapping. The proposed technique, scalable scanning, allows for an effective
comparison even if the shapes and sizes of the feet projections appear
differently in the image. The tested results show that asymmetry analysis-
based scalable scanning provides fewer false abnormal areas than does asymmetry
analysis -based overlapping.


title: On PNT equivalences for Beurling numbers

abstract:
  In classical prime number theory several asymptotic relations are considered
to be "equivalent" to the prime number theorem. In the setting of Beurling
generalized numbers, this may no longer be the case. Under additional
hypotheses on the generalized integer counting function, one can however still
deduce various equivalences between the Beurling analogues of the classical PNT
relations. We establish some of the equivalences under weaker conditions than
were known so far.


title: Parameter identification in a semilinear hyperbolic system

abstract:
  We consider the identification of a nonlinear friction law in a
one-dimensional damped wave equation from additional boundary measurements.
Well-posedness of the governing semilinear hyperbolic system is established via
semigroup theory and contraction arguments. We then investigte the inverse
problem of recovering the unknown nonlinear damping law from additional
boundary measurements of the pressure drop along the pipe. This coefficient
inverse problem is shown to be ill-posed and a variational regularization
method is considered for its stable solution. We prove existence of minimizers
for the Tikhonov functional and discuss the convergence of the regularized
solutions under an approximate source condition. The meaning of this condition
and some arguments for its validity are discussed in detail and numerical
results are presented for illustration of the theoretical findings.


title: One generalization of the classical moment problem

abstract:
  Let $\ast_P$ be a product on $l_{\rm{fin}}$ (a space of all finite sequences)
associated with a fixed family $(P_n)_{n=0}^{\infty}$ of real polynomials on
$\mathbb{R}$. In this article, using methods from the theory of generalized
eigenvector expansion, we investigate moment-type properties of
$\ast_P$-positive functionals on $l_{\rm{fin}}$. If $(P_n)_{n=0}^{\infty}$ is a
family of the Newton polynomials $P_n(x)=\prod_{i=0}^{n-1}(x-i)$ then the
corresponding product $\star=\ast_P$ is an analog of the so-called
Kondratiev--Kuna convolution on a "Fock space". We get an explicit expression
for the product $\star$ and establish a connection between $\star$-positive
functionals on $l_{\rm{fin}}$ and a one-dimensional analog of the Bogoliubov
generating functionals (the classical Bogoliubov functionals are defined
correlation functions for statistical mechanics systems).


title: Observations of the Lensed Quasar Q2237+0305 with CanariCam at GTC

abstract:
  We present new mid-IR observations of the quadruply lensed quasar Q2237+0305
taken with CanariCam on the Gran Telescopio Canarias. Mid-IR emission by hot
dust, unlike the optical and near-IR emission from the accretion disk, is
unaffected by the interstellar medium (extinction/scattering) or stellar
microlensing. We compare these "true" ratios to the (stellar) microlensed flux
ratios observed in the optical/near-IR to constrain the structure of the quasar
accretion disk. We find a half-light radius of
$R_{1/2}=3.4_{-2.1}^{+5.3}\sqrt{\langle M \rangle/0.3\,\rm{M_{\odot}}}$
light-days at $\lambda_{rest}=1736$ {\AA}, and an exponent for the temperature
profile $R \propto \lambda^{p}$ of $p=0.79\pm0.55$, where $p=4/3$ for a
standard thin-disk model. If we assume that the differences in the mid-IR flux
ratios measured over the years are due to microlensing variability, we find a
lower limit for the size of the mid-IR-emitting region of $R_{1/2} \gtrsim
200\,\sqrt{\langle M \rangle/0.3\,\rm{M_{\odot}}}$ light-days. We also test for
the presence of substructure/satellites by comparing the observed mid-IR flux
ratios with those predicted from smooth lens models. We can explain the
differences if the surface density fraction in satellites near the lensed
images is $\alpha = 0.033_{-0.019}^{+0.046}$ for a singular isothermal
ellipsoid plus external shear mass model or $\alpha = 0.013_{-0.008}^{+0.019}$
for a mass model combining ellipsoidal NFW and de Vaucouleurs profiles in an
external shear.


title:
Amplitude-based detection method for gravitational wave bursts with the
  Hilbert-Huang Transform

abstract:
  We propose a new detection method for gravitational wave bursts. It analyzes
observed data with the Hilbert-Huang transform, which is an approach of
time-frequency analysis constructed with the aim of manipulating non-linear and
non-stationary data. Using the simulated time-series noise data and waveforms
from rotating core-collapse supernovae at 30 kpc, we performed simulation to
evaluate the performance of our method and it revealed the total detection
probability to be 0.94 without false alerms, which corresponds to the false
alarm rate < 0.001 Hz. The detection probability depends on the characteristics
of the waveform, but it was found that the parameter determining the degree of
differential rotation of the collapsing star is the most important for the
performance of our method.


title: Symmetries of projective spaces and spheres

abstract:
  Let $H$ be either a complex inner product space of dimension at least two, or
a real inner product space of dimension at least three. Let us fix an
$\alpha\in \left(0,\tfrac{\pi}{2}\right)$. The purpose of this paper is to
characterize all bijective transformations on the projective space $P(H)$
obtained from $H$ which preserves the angle $\alpha$ between lines in both
directions. (We emphasize that we do not assume anything about other angles).
For real inner product spaces and when $H=\mathbb{C}^2$ we do this for every
$\alpha$, and when $H$ is a complex inner product space of dimension at least
three we describe the structure of these transformations for
$\alpha\leq\tfrac{\pi}{4}$. As an application, we give an Uhlhorn-type
generalization of a famous theorem of Wigner which is considered to be a
cornerstone of the mathematical foundations of quantum mechanics. Namely, we
show that under the above assumptions, every bijective map on the set of pure
states of a quantum mechanical system that preserves the transition probability
$\cos^2\alpha$ in both directions is a Wigner symmetry (i.e. it automatically
preserves all transition probability), except for the case when
$H=\mathbb{C}^2$ and $\alpha = \tfrac{\pi}{4}$ where an additional possibility
occurs. We note that the classical theorem of Uhlhorn is the solution for the
$\alpha = \tfrac{\pi}{2}$ case. Usually in the literature, results which are
connected to Wigner's theorem are discussed under the assumption of
completeness of $H$, however, here we shall remove this unnecessary hypothesis.
Our main tools are a characterization of bijective maps on unit spheres of real
inner product spaces which preserve an angle in both directions, and an
extension of Uhlhorn's theorem for non-complete inner product spaces.


title:
On the complexity of probabilistic trials for hidden satisfiability
  problems

abstract:
  What is the minimum amount of information and time needed to solve 2SAT? When
the instance is known, it can be solved in polynomial time, but is this also
possible without knowing the instance? Bei, Chen and Zhang (STOC '13)
considered a model where the input is accessed by proposing possible
assignments to a special oracle. This oracle, on encountering some constraint
unsatisfied by the proposal, returns only the constraint index. It turns out
that, in this model, even 1SAT cannot be solved in polynomial time unless P=NP.
Hence, we consider a model in which the input is accessed by proposing
probability distributions over assignments to the variables. The oracle then
returns the index of the constraint that is most likely to be violated by this
distribution. We show that the information obtained this way is sufficient to
solve 1SAT in polynomial time, even when the clauses can be repeated. For 2SAT,
as long as there are no repeated clauses, in polynomial time we can even learn
an equivalent formula for the hidden instance and hence also solve it.
Furthermore, we extend these results to the quantum regime. We show that in
this setting 1QSAT can be solved in polynomial time up to constant precision,
and 2QSAT can be learnt in polynomial time up to inverse polynomial precision.


title: Hydrodynamics of Domain Walls in Multiferroics: Impact on Memory Devices

abstract:
  We show that switching in ferroelectric lead germanate and lead iron
tantalate zirconate titanate (PZTFT) does not resemble the equilibrium domain
structure evolution of the Landau-Lifshitz-Kittel model but is instead highly
nonequilibrium and similar, respectively, to the Richtmyer-Meshkov instability
in liquids and the Helfrich-Hursault sliding instability in liquid crystals.
The resulting nano-domain structures in PZTFT are circular or parabolic and
involving folding bifurcations. These may have an undesirable impact on
ferroelectric thin-film memoriesthat are also ferroelastic.


title: Novikov homology and noncommutative Alexander polynomials

abstract:
  In the early 2000's Cochran and Harvey introduced non-commutative Alexander
polynomials for 3-manifolds. Their degrees give strong lower bounds on the
Thurston norm. In this paper we make the case that the vanishing of a certain
Novikov-Sikorav homology module is the correct notion of a monic
non-commutative Alexander polynomial. Furthermore we will use the opportunity
to give new proofs of several statements about Novikov-Sikorav homology in the
three-dimensional context.


title: Egalitarian computing

abstract:
  In this paper we explore several contexts where an adversary has an upper
hand over the defender by using special hardware in an attack. These include
password processing, hard-drive protection, cryptocurrency mining, resource
sharing, code obfuscation, etc. We suggest memory-hard computing as a generic
paradigm, where every task is amalgamated with a certain procedure requiring
intensive access to RAM both in terms of size and (very importantly) bandwidth,
so that transferring the computation to GPU, FPGA, and even ASIC brings little
or no cost reduction. Cryptographic schemes that run in this framework become
egalitarian in the sense that both users and attackers are equal in the
price-performance ratio conditions. Based on existing schemes like {Argon2} and
the recent generalized-birthday proof-of-work, we suggest a generic framework
and two new schemes: MTP, a memory-hard Proof-of-Work based on the memory-hard
function with fast verification and short proofs. It can be also used for
memory-hard time-lock puzzles. {MHE}, the concept of memory-hard encryption,
which utilizes available RAM to strengthen the encryption for the low-entropy
keys (allowing to bring back 6 letter passwords).


title: Chiral magnetic effect by synthetic gauge fields

abstract:
  We study the dynamical generation of the chiral chemical potential in a Weyl
metal constructed from a three-dimensional optical lattice and subject to
synthetic gauge fields. By numerically solving the Boltzmann equation with the
Berry curvature in the presence of parallel synthetic electric and magnetic
fields, we find that the spectral flow and the ensuing chiral magnetic current
emerge. We show that the spectral flow and the chiral chemical potential can be
probed by time-of-flight imaging.

categories: cond-mat.quant-gas cond-mat.mes-hall hep-ph hep-th nucl-th


title:
Market Microstructure During Financial Crisis: Dynamics of Informed and
  Heuristic-Driven Trading

abstract:
  We implement a market microstructure model including informed, uninformed and
heuristic-driven investors, which latter behave in line with loss-aversion and
mental accounting. We show that the probability of informed trading (PIN)
varies significantly during 2008. In contrast, the probability of
heuristic-driven trading (PH) remains constant both before and after the
collapse of Lehman Brothers. Cross-sectional analysis yields that, unlike PIN,
PH is not sensitive to size and volume effects. We show that heuristic-driven
traders are universally present in all market segments and their presence is
constant over time. Furthermore, we find that heuristic-driven investors and
informed traders are disjoint sets.


title:
Additive Energy and the Hausdorff dimension of the exceptional set in
  metric pair correlation problems

abstract:
  For a sequence of integers $\{a(x)\}_{x \geq 1}$ we show that the
distribution of the pair correlations of the fractional parts of $\{ \langle
\alpha a(x) \rangle \}_{x \geq 1}$ is asymptotically Poissonian for almost all
$\alpha$ if the additive energy of truncations of the sequence has a power
savings improvement over the trivial estimate. Furthermore, we give an estimate
for the Hausdorff dimension of the exceptional set as a function of the density
of the sequence and the power savings in the energy estimate. A consequence of
these results is that the Hausdorff dimension of the set of $\alpha$ such that
$\{\langle \alpha x^d \rangle\}$ fails to have Poissonian pair correlation is
at most $\frac{d+2}{d+3} < 1$. This strengthens a result of Rudnick and Sarnak
which states that the exceptional set has zero Lebesgue measure. On the other
hand, classical examples imply that the exceptional set has Hausdorff dimension
at least $\frac{2}{d+1}$.
  An appendix by Jean Bourgain was added after the first version of this paper
was written. In this appendix two problems raised in the paper are solved.


title: Balanced activation in a simple embodied neural simulation

abstract:
  In recent years, there have been many computational simulations of
spontaneous neural dynamics. Here, we explore a model of spontaneous neural
dynamics and allow it to control a virtual agent moving in a simple
environment. This setup generates interesting brain-environment feedback
interactions that rapidly destabilize neural and behavioral dynamics and
suggest the need for homeostatic mechanisms. We investigate roles for both
local homeostatic plasticity (local inhibition adjusting over time to balance
excitatory input) as well as macroscopic task negative activity (that
compensates for task positive, sensory input) in regulating both neural
activity and resulting behavior (trajectories through the environment). Our
results suggest complementary functional roles for both local homeostatic
plasticity and balanced activity across brain regions in maintaining neural and
behavioral dynamics. These findings suggest important functional roles for
homeostatic systems in maintaining neural and behavioral dynamics and suggest a
novel functional role for frequently reported macroscopic task-negative
patterns of activity (e.g., the default mode network).


title:
Amalgamated duplication of the Banach algebra $\bf{\frak A}$ along a
  ${\frak A}$-bimodule ${\mathcal A}$

abstract:
  Let ${\mathcal A}$ and ${\frak A}$ be Banach algebras such that ${\mathcal
A}$ is a Banach ${\frak A}$-bimodule with compatible actions. We define the
product ${\cal A}\rtimes{\frak A}$, which is a strongly splitting Banach
algebra extension of ${\frak A}$ by $\cal A$. After characterization of the
multiplier algebra, topological centre, (maximal) ideals and spectrum of ${\cal
A}\rtimes{\frak A}$, we restrict our investigation to the study of
semisimplicity, regularity, Arens regularity of ${\cal A}\rtimes{\frak A}$ in
relation to that of the algebras $\cal A$, $\frak A$ and the action of $\frak
A$ on $\cal A$. We also compute the first cohomology group $H^1{(}{\cal
A}\rtimes{\frak A},({\cal A}\rtimes{\frak A})^{(n)}{)}$ for all $n\in {\Bbb
N}\cup\{0\}$ as well as the first-order cyclic cohomology group
$H_\lambda^1{(}{\cal A}\rtimes{\frak A},({\cal A}\rtimes{\frak A})^{(1)}{)}$,
where $({\cal A}\rtimes{\frak A})^{(n)}$ is the n-th dual space of ${\cal
A}\rtimes{\frak A}$ when $n\in{\Bbb N}$ and ${\cal A}\rtimes{\frak A}$ itself
when $n=0$. These results are not only of interest in their own right, but also
they pave the way for obtaining some new results for Lau products and module
extensions of Banach algebras as well as triangular Banach algebra. Finally,
special attention is devoted to the cyclic and $n$-weak amenability of ${\cal
A}\rtimes{\frak A}$.


title: Evolution of moments of isotropic Brownian stochastic flows

abstract:
  In this paper we consider the asymptotic behaviour of all moments of the
interparticle distance and of all mixed moments of an isotropic Brownian
stochastic flow which serves as a smooth approximation of the Arratia flow.


title: Incentivizing Resilience in Financial Networks

abstract:
  When banks extend loans to each other, they generate a negative externality
in the form of systemic risk. They create a network of interbank exposures by
which they expose other banks to potential insolvency cascades. In this paper,
we show how a regulator can use information about the financial network to
devise a transaction-specific tax based on a network centrality measure that
captures systemic importance. Since different transactions have different
impact on creating systemic risk, they are taxed differently. We call this tax
a Systemic Risk Tax (SRT). We use an equilibrium concept inspired by the
matching markets literature to show analytically that this SRT induces a unique
equilibrium matching of lenders and borrowers that is systemic-risk efficient,
i.e. it minimizes systemic risk given a certain transaction volume. On the
other hand, we show that without this SRT multiple equilibrium matchings exist,
which are generally inefficient. This allows the regulator to effectively
stimulate a `rewiring' of the equilibrium interbank network so as to make it
more resilient to insolvency cascades, without sacrificing transaction volume.
Moreover, we show that a standard financial transaction tax (e.g. a Tobin-like
tax) has no impact on reshaping the equilibrium financial network because it
taxes all transactions indiscriminately. A Tobin-like tax is indeed shown to
have a limited effect on reducing systemic risk while it decreases transaction
volume.


title: Bio-inspired hierarchical dissipative metamaterials

abstract:
  Hierarchical structures with constituents over multiple length scales are
found in various natural materials like bones, shells, spider silk and others,
all of which display enhanced quasi-static mechanical properties, such as high
specific strength, stiffness and toughness. At the same time, the role of
hierarchy on the dynamic behaviour of metamaterials remains largely unexplored.
This study assesses the effect of bio-inspired hierarchical organization as
well as of viscoelasticity on the wave attenuation properties of continuous
mechanical metamaterials. We consider single-phase metamaterials formed by
self-similar unit cells with different hierarchical levels and types of
hierarchy. Results highlight a number of advantages through the introduction of
structural hierarchy. Band gaps relative to the corresponding non-hierarchical
structures are mostly preserved, while additional "hierarchically-induced" band
gaps appear. Additionally, the hierarchical configuration allows the tuning of
the band gap frequencies of regular metamaterial to lower frequencies, with a
simultaneous significant reduction of the global structural weight. We show
that even small viscoelastic effects, not treated in the current literature,
are essential in determining this behaviour. The approach we propose allows the
addition of hierarchical elements to existing metamaterial configurations, with
the corresponding improvement of the wave damping properties, thus providing
indications for the design of structures for practical applications.


title:
Unravelling the Asymmetric Volatility Puzzle: A Novel Explanation of
  Volatility Through Anchoring

abstract:
  This paper discusses a novel explanation for asymmetric volatility based on
the anchoring behavioral pattern. Anchoring as a heuristic bias causes
investors focusing on recent price changes and price levels, which two lead to
a belief in continuing trend and mean-reversion respectively. The empirical
results support our theoretical explanation through an analysis of large price
fluctuations in the S&P 500 and the resulting effects on implied and realized
volatility. These results indicate that asymmetry (a negative relationship)
between shocks and volatility in the subsequent period indeed exists. Moreover,
contrary to previous research, our empirical tests also suggest that implied
volatility is not simply an upward biased predictor of future deviation
compensating for the variance of the volatility but rather, due to investors
systematic anchoring to losses and gains in their volatility forecasts, it is a
co-integrated yet asymmetric over/under estimated financial instrument. We also
provide results indicating that the medium-term implied volatility (measured by
the VIX Index) is an unbiased though inefficient estimation of realized
volatility, while in contrast, the short-term volatility (measured by the
recently introduced VXST Index representing the 9-day implied volatility) is
also unbiased and yet efficient.


title: Nested Weighted Limit-Average Automata of Bounded Width

abstract:
  While weighted automata provide a natural framework to express quantitative
properties, many basic properties like average response time cannot be
expressed with weighted automata. Nested weighted automata extend weighted
automata and consist of a master automaton and a set of slave automata that are
invoked by the master automaton. Nested weighted automata are strictly more
expressive than weighted automata (e.g., average response time can be expressed
with nested weighted automata), but the basic decision questions have higher
complexity (e.g., for deterministic automata, the emptiness question for nested
weighted automata is PSPACE-hard, whereas the corresponding complexity for
weighted automata is PTIME). We consider a natural subclass of nested weighted
automata where at any point at most a bounded number k of slave automata can be
active. We focus on automata whose master value function is the limit average.
We show that these nested weighted automata with bounded width are strictly
more expressive than weighted automata (e.g., average response time with no
overlapping requests can be expressed with bound k=1, but not with non-nested
weighted automata). We show that the complexity of the basic decision problems
(i.e., emptiness and universality) for the subclass with k constant matches the
complexity for weighted automata. Moreover, when k is part of the input given
in unary we establish PSPACE-completeness.


title:
Robust integral formulations for electromagnetic scattering from
  three-dimensional cavities

abstract:
  Scattering from large, open cavity structures is of importance in a variety
of electromagnetic applications. In this paper, we propose a new well
conditioned integral equation for scattering from general open cavities
embedded in an infinite, perfectly conducting half-space. The integral
representation permits the stable evaluation of both the electric and magnetic
field, even in the low-frequency regime, using the continuity equation in a
post-processing step. We establish existence and uniqueness results, and
demonstrate the performance of the scheme in the cavity-of-revolution case.
High-order accuracy is obtained using a Nystrom discretization with generalized
Gaussian quadratures.


title:
Beyond the Ultra-Dense Barrier - Paradigm shifts on the road beyond
  1000x wireless capacity

abstract:
  It has become increasingly clear that the current design paradigm for mobile
broadband systems is not a scalable and economically feasible way to solve the
expected future 'capacity crunch', in particular in indoor locations with large
user densities. 'Moore's law', e.g. state-of-the art signal processing and
advanced antenna techniques now being researched, as well as more millimeter
wave spectrum indeed provide more capacity, but are not the answer to the 3-4
orders of magnitude more capacity at today's cost, that is needed.We argue that
solving the engineering problem of providing high data rates alone is not
sufficient. Instead we need to solve the techno-economic problem to find both
business models and scalable technical solutions that provide extreme area
capacity for a given cost and energy consumption. In this paper we will show
that achieving very high capacities is indeed feasible in indoor environments.


title:
TRex: A Tomography Reconstruction Proximal Framework for Robust Sparse
  View X-Ray Applications

abstract:
  We present TRex, a flexible and robust Tomographic Reconstruction framework
using proximal algorithms. We provide an overview and perform an experimental
comparison between the famous iterative reconstruction methods in terms of
reconstruction quality in sparse view situations. We then derive the proximal
operators for the four best methods. We show the flexibility of our framework
by deriving solvers for two noise models: Gaussian and Poisson; and by plugging
in three powerful regularizers. We compare our framework to state of the art
methods, and show superior quality on both synthetic and real datasets.


title: New results for the Liebau phenomenon via fixed point index

abstract:
  We prove new results regarding the existence of positive solutions for a
nonlinear periodic boundary value problem related to the Liebau phenomenon. As
a consequence we obtain new sufficient conditions for the existence of a pump
in a simple model. Our methodology relies on the use of classical fixed point
index. Some examples are provided to illustrate our theory. We improve and
complement previous results in the literature.


title: Guided Waves in Asymmetric Hyperbolic Slab Waveguides. The TM Mode Case

abstract:
  Nonlinear guided wave modes in an asymmetric slab waveguide formed by an
isotropic dielectric layer placed on a linear or nonlinear substrate and
covered by a hyperbolic material are investigated. Optical axis is normal to
the slab plane. The dispersion relations for TM waves are found. It is shown
that there are additional cut-off frequencies for each TM mode. The effects of
the nonlinearity on the dispersion relations are investigated and discussed.
There are the modes, which are corresponded with situation where the peak of
electric field is localized in the nonlinear substrate. These modes are absent
in the linear waveguide. To excite these modes the power must exceed certain
threshold value.


title: Topology of mixed hypersurfaces of cyclic type

abstract:
  We study a simplicial mixed polynomial of cyclic type and its associated
weighted homogeneous polynomial. In the present paper, we show that their links
are diffeomorphic and their Milnor fibrations are isomorphic.


title: RG Domain Wall for the General su(2) Coset Models

abstract:
  We consider a RG flow in a general su(2) coset model induced by the least
relevant field. This is done using two different approaches. We first compute
the mixing coefficients of certain fields in the UV and IR theories using a
conformal perturbation theory. The necessary structure constants are computed.
The same coefficients can be calculated using the RG domain wall construction
of Gaiotto. We compute the corresponding one-point functions and show that the
two approaches give the same result in the leading order.


title: CMB foregrounds - A brief review

abstract:
  CMB foregrounds consist of all radiation between the surface of last
scattering and the detectors, which can interfere with the cosmological
interpretation of CMB data. Fortunately, in temperature (intensity), even
though the foregrounds are complex they can relatively easily be mitigated.
However, in polarization, diffuse Galactic radiation (synchrotron and thermal
dust) can be polarized at a level of >10 % making it more of a challenge. In
particular, CMB B-modes, which are a smoking-gun signature of inflation, will
be dominated by foregrounds. Component separation will therefore be critical
for future CMB polarization missions, requiring many channels covering a wide
range of frequencies, to ensure that foreground modelling errors are minimised.


title: Equivariant Moore spaces and the Dade group

abstract:
  Let $G$ be a finite $p$-group and $k$ be a field of characteristic $p$. A
topological space $X$ is called an $n$-Moore space if its reduced homology is
nonzero only in dimension $n$. We call a $G$-CW-complex $X$ an
$\underline{n}$-Moore $G$-space over $k$ if for every subgroup $H$ of $G$, the
fixed point set $X^H$ is an $\underline{n}(H)$-Moore space with coefficients in
$k$, where $\underline{n}(H)$ is a function of $H$. We show that if $X$ is a
finite $\underline{n}$-Moore $G$-space, then the reduced homology module of $X$
is an endo-permutation $kG$-module generated by relative syzygies. A
$kG$-module $M$ is an endo-permutation module if ${\rm End}_k (M) =M \otimes
_{k} M^*$ is a permutation $kG$-module. We consider the Grothendieck group of
finite Moore $G$-spaces $\mathcal{M}(G)$, with addition given by the join
operation, and relate this group to the Dade group generated by relative
syzygies.


title: Whitney towers and abelian invariants of knots

abstract:
  We relate certain abelian invariants of a knot, namely the Alexander
polynomial, the Blanchfield form, and the Arf invariant, to intersection data
of a Whitney tower in the 4-ball bounded by the knot. We also give a new
3-dimensional algorithm for computing these invariants.


title:
Singularities of slice regular functions over real alternative
  *-algebras

abstract:
  The main goal of this work is classifying the singularities of slice regular
functions over a real alternative *-algebra A. This function theory has been
introduced in 2011 as a higher-dimensional generalization of the classical
theory of holomorphic complex functions, of the theory of slice regular
quaternionic functions launched by Gentili and Struppa in 2006 and of the
theory of slice monogenic functions constructed by Colombo, Sabadini and
Struppa since 2009. Along with this generalization step, the larger class of
slice functions over A has been defined. We introduce here a new type of series
expansion near each singularity of a slice regular function. This instrument,
which is new even in the quaternionic case, leads to a complete classification
of singularities. This classification also relies on some recent developments
of the theory, concerning the algebraic structure and the zero sets of slice
functions. Peculiar phenomena arise, which were not present in the complex or
quaternionic case, and they are studied by means of new results on the topology
of the zero sets of slice functions. The analogs of meromorphic functions,
called (slice) semiregular functions, are introduced and studied.


title: On the Concept of Static Structure Factor

abstract:
  We clarify the confusion in the expression of the static structure factor
S(k) in the study of condensed matters and discuss its explicit form that can
be directly used in calculations and computer simulations.


title: Squeezed Helical Elastica

abstract:
  We theoretically study the conformations of a helical semi-flexible filament
confined to a flat surface. This squeezed helix exhibits a variety of
unexpected shapes resembling circles, waves or spirals depending on the
material parameters. We explore the conformation space in detail and show that
the shapes can be understood as the mutual elastic interaction of
conformational quasi-particles. Our theoretical results are potentially useful
to determine the material parameters of such helical filaments in an
experimental setting.


title:
Nahm transformation for parabolic Higgs bundles on the projective line
  --- case of non-semisimple residues

abstract:
  We extend our earlier construction of Nahm transformation for parabolic Higgs
bundles on the projective line to solutions with not necessarily semisimple
residues and show that it determines a holomorphic mapping on corresponding
moduli spaces. The construction relies on suitable elementary modifications of
the logarithmic Dolbeault complex.


title: Gaussian curvature as an identifier of shell rigidity

abstract:
  In the paper we deal with shells with non-zero Gaussian curvature. We derive
sharp Korn's first (linear geometric rigidity estimate) and second inequalities
on that kind of shells for zero or periodic Dirichlet, Neumann, and Robin type
boundary conditions. We prove that if the Gaussian curvature is positive, then
the optimal constant in the first Korn inequality scales like $h,$ and if the
Gaussian curvature is negative, then the Korn constant scales like $h^{4/3},$
where $h$ is the thickness of the shell. These results have classical flavour
in continuum mechanics, in particular shell theory. The Korn first inequalities
are the linear version of the famous geometric rigidity estimate by Friesecke,
James and M\"uller for plates [14] (where they show that the Korn constant in
the nonlinear Korn's first inequality scales like $h^2$), extended to shells
with nonzero curvature. We also recover the uniform Korn-Poincar\'e inequality
proven for "boundary-less" shells by Lewicka and M\"uller in [37] in the
setting of our problem. The new estimates can also be applied to find the
scaling law for the critical buckling load of the shell under in-plane loads as
well as to derive energy scaling laws in the pre-buckled regime. The exponents
$1$ and $4/3$ in the present work appear for the first time in any sharp
geometric rigidity estimate.


title:
Femtosecond spin current pulses generated by the non-thermal
  spin-dependent Seebeck effect and interacting with ferromagnets in spin
  valves

abstract:
  Using the sensitivity of magneto-induced second harmonic generation to spin
currents (SC), we demonstrate in Fe/Au/Fe/MgO(001) pseudo spin valves the
generation of 250 fs-long SC pulses. Their temporal profile indicates that
superdiffusive hot electron transport across a sub-100~nm Au layer is close to
the ballistic limit and the pulse duration is primarily determined by the
thermalization time of laser-excited hot carriers in Fe. Considering the
calculated spin-dependent Fe/Au interface transmittance we conclude that a
non-thermal spin-dependent Seebeck effect is responsible for the generation of
ultrashort SC pulses. We also show that hot electron spins rotate upon
interaction with non-collinear magnetization at the Au/Fe interface, which
holds high potential for future spintronic devices.


title:
A Gleason-type theorem for any dimension based on a gambling formulation
  of Quantum Mechanics

abstract:
  Based on a gambling formulation of quantum mechanics, we derive a
Gleason-type theorem that holds for any dimension n of a quantum system, and in
particular for n = 2. The theorem states that the only logically consistent
probability assignments are exactly the ones that are definable as the trace of
the product of a projector and a density matrix operator. In addition, we
detail the reason why dispersion-free probabilities are actually not valid, or
rational, probabilities for quantum mechanics, and hence should be excluded
from consideration.


title:
Random alloy fluctuations and structural inhomogeneities in $c$-plane
  In$_{x}$Ga$_{1-x}$N quantum wells: theory of ground and excited electron and
  hole states

abstract:
  We present a detailed theoretical analysis of the electronic structure of
$c$-plane InGaN/GaN quantum wells with indium contents varying between 10\% and
25\%. The electronic structure of the quantum wells is treated by means of an
atomistic tight-binding model, accounting for variations in strain and built-in
field due to random alloy fluctuations. Our analysis reveals strong
localisation effects in the hole states. These effects are found not only in
the ground states, but also the excited states. We conclude that localisation
effects persist to of order 100~meV into the valence band, for as little as
10\% indium in the quantum well, giving rise to a significant density of
localised states. We find, from an examination of the modulus overlap of the
wave functions, that the hole states can be divided into three regimes of
localisation. Our results also show that localisation effects due to random
alloy fluctuations are far less pronounced for electron states. However, the
combination of electrostatic built-in field, alloy fluctuations and structural
inhomogeneities, such as well-width fluctuations, can nevertheless lead to
significant localisation effects in the electron states, especially at higher
indium contents. Overall, our results are indicative of individually localised
electron and hole states, consistent with the experimentally proposed
explanation of time-dependent photoluminescence results in $c$-plane InGaN/GaN
QWs.


title: Equations in Algebras

abstract:
  We show that the Diophantine problem(decidability of equations) is
undecidable in free associative algebras over any field and in the group
algebras over any field of a wide variety of torsion free groups, including
toral relatively hyperbolic groups, right angled Artin groups, commutative
transitive groups, the fundamental groups of various graph groups, etc.