8,327 research outputs found
Interpenetration as a Mechanism for Liquid-Liquid Phase Transitions
We study simple lattice systems to demonstrate the influence of
interpenetrating bond networks on phase behavior. We promote interpenetration
by using a Hamiltonian with a weakly repulsive interaction with nearest
neighbors and an attractive interaction with second-nearest neighbors. In this
way, bond networks will form between second-nearest neighbors, allowing for two
(locally) distinct networks to form. We obtain the phase behavior from analytic
solution in the mean-field approximation and exact solution on the Bethe
lattice. We compare these results with exact numerical results for the phase
behavior from grand canonical Monte Carlo simulations on square, cubic, and
tetrahedral lattices. All results show that these simple systems exhibit rich
phase diagrams with two fluid-fluid critical points and three thermodynamically
distinct phases. We also consider including third-nearest-neighbor
interactions, which give rise to a phase diagram with four critical points and
five thermodynamically distinct phases. Thus the interpenetration mechanism
provides a simple route to generate multiple liquid phases in single-component
systems, such as hypothesized in water and observed in several model and
experimental systems. Additionally, interpenetration of many such networks
appears plausible in a recently considered material made from nanoparticles
functionalized by single strands of DNA.Comment: 12 pages, 9 figures, submitted to Phys. Rev.
Qualitative picture of a new mechanism for high-Tc superconductors
Xu et al. observed enhanced Nernst effect and Iguchi et al. observed patched
diamagnetism, both well above in underdoped high- superconductors
(HTSCs). A new mechanism is proposed here, which seems to naturally explain, at
least qualitatively, these observations, as well as the d-wave nature and
continuity of pseudogap and pairing gap, the tunneling conductance above ,
as well as , , , etc. This mechanism combines
features of dynamic charged stripes, preformed pairs, and spin-bags: At
appropriete doping levels, the doped holes (and perhaps also electrons) will
promote the formation of anti-phase islands in short-range anti-ferromagnetic
order. On the boundary of each such island reside two doped carriers; the
unscreened Coulomb repulsion between them stabilizes its size.
Superconductivity results when such ``pre-formed pairs'' Bose-condense.Comment: 8 pages, 4 figures, New3SC-4 Conference Proceedings, to be published
in ijmp
Tertiary Performance, Field of Study and Graduate Starting Salaries
This paper analyses data from the University of Western Australia (UWA) Graduate Destination Survey linked to information from the University’s Student Records System to explore the determinants of graduates’ starting salaries over the years 2002 to 2004. While the details examined also include age, gender, language spoken at home, country of birth, disability status and high school attended, most emphasis is placed on the impact on starting salaries of students’ academic performance and their field of study. The analyses show that the main determinant of graduates’ starting salaries is the weighted average mark they achieve at university. The salary differentials associated with higher marks in the Australian labour market appear greater than those reported in similar studies of the United States and United Kingdom labour markets. Science graduates are shown to have relatively low starting salaries, casting a shadow over recent suggestions that the supply of this group be increased through lower fee regimes.Starting Salaries, Ability, Field of Study
Differential Entropy on Statistical Spaces
We show that the previously introduced concept of distance on statistical
spaces leads to a straightforward definition of differential entropy on these
statistical spaces. These spaces are characterized by the fact that their
points can only be localized within a certain volume and exhibit thus a feature
of fuzziness. This implies that Riemann integrability of relevant integrals is
no longer secured. Some discussion on the specialization of this formalism to
quantum states concludes the paper.Comment: 4 pages, to appear in the proceedings of the joint meeting of the 2nd
International Conference on Cybernetics and Information Technologies, Systems
and Applications (CITSA 2005) and the 11th International Conference on
Information Systems Analysis and Synthesis (ISAS 2005), to be held in
Orlando, USA, on July 14-17, 200
The ChIP-seq-defined networks of Bcl-3 gene binding support its required role in skeletal muscle atrophy
NF-kappaB transcriptional activation is required for skeletal muscle disuse atrophy. We are continuing to study how the activation of NF-kB regulates the genes that encode the protein products that cause atrophy. Using ChIP-sequencing we found that Bcl-3, an NF-kB transcriptional activator required for atrophy, binds to the promoters of a number of genes whose collective function describes two major aspects of muscle wasting. By means of bioinformatics analysis of ChIP-sequencing data we found Bcl-3 to be directing transcription networks of proteolysis and energy metabolism. The proteolytic arm of the Bcl-3 networks includes many E3 ligases associated with proteasomal protein degradation, including that of the N-end rule pathway. The metabolic arm appears to be involved in organizing the change from oxidative phosphorylation to glycolysis in atrophying muscle. For one gene, MuRF1, ChIP-sequencing data identified the location of Bcl-3 and p50 binding in the promoter region which directed the creation of deletant and base-substitution mutations of MuRF1 promoter constructs to determine the effect on gene transcription. The results provide the first direct confirmation that the NF-kB binding site is involved in the muscle unloading regulation of MuRF1. Finally, we have combined the ChIP-sequencing results with gene expression microarray data from unloaded muscle to map several direct targets of Bcl-3 that are transcription factors whose own targets describe a set of indirect targets for NF-kB in atrophy. ChIP-sequencing provides the first molecular explanation for the finding that Bcl3 knockout mice are resistant to disuse muscle atrophy. Mapping the transcriptional regulation of muscle atrophy requires an unbiased analysis of the whole genome, which we show is now possible with ChIP-sequencing.R01 AR041705 - NIAMS NIH HHS; R01 AR060217 - NIAMS NIH HHS; AR041705 - NIAMS NIH HHS; AR060217 - NIAMS NIH HH
The review of migration decisions — a story of borders and orders
In the last decade in Australia and the United Kingdom, the review of
immigration decisions in tribunals and courts has been marked by constitutional
conflict between the executive and the judiciary; a crisis of confidence; and continual
change. This thesis explores what this tumultuous story of immigration review tells us
about the law — as a social practice, as an institution, and as a linguistic genre — in
these jurisdictions, in these times.
This thesis argues that the story of immigration review is explained best not
through the conventional story of a battle between the executive and the judiciary,
but rather as a story of the fundamental challenges immigration poses to the social,
institutional, ideological and linguistic dimensions of law, and of the attempt by
judges and the legal community to defend their different conceptions of the
legitimacy of the law from those challenges, in different ways.
Four fundamental challenges are identified. First, immigration challenges the
coherence of the legal framework, as it exposes tensions within and between the
different legal regimes. Second, the more reductive language used in legal contexts
competes badly with more complex, and more socially powerful, discourses about
immigration. Third, immigration challenges the capacity of law to perform the
functions of resolving disputes and regulating behaviour. Fourth, immigration
challenges our deepest concepts of legality.
The thesis examines these challenges, and the responses they provoke, by
drawing on the insights of migration studies, contemporary political philosophy,
language and the law, and regulatory theory, as well as examining important case law
in detail. In doing so, it aims both to capture the story of immigration review more
fully, and to illuminate some of the complexities of, and limits to, the contemporary
social practice of law
Theoretical description of a DNA-linked nanoparticle self-assembly
Nanoparticles tethered with DNA strands are promising building blocks for
bottom-up nanotechnology, and a theoretical understanding is important for
future development. Here we build on approaches developed in polymer physics to
provide theoretical descriptions for the equilibrium clustering and dynamics,
as well as the self-assembly kinetics of DNA-linked nanoparticles. Striking
agreement is observed between the theory and molecular modeling of DNA tethered
nanoparticles.Comment: Accepted for publication in Physical Review Letter
Estimating the Fair Insurance Premium for Dungeness Crab Yields in the Western U.S. Coast
The Dungeness is a popular food and the most commercially important crab in the western states in the U.S. Like all agricultural production, the crab fisherman face yield risks and must manage these risks. In addition to weather risk, crab fisherman may experience low yields if the crabs are over fished in previous years. Farmers for many traditional agricultural crops can purchase crop insurance to insure against low yields. However, crab fishermen at this time do not have this option. The purpose of this paper is to estimate a fair insurance premium based on the historical yields of the Dungeness crab. This information can then be used in risk/return models for crab fishing to determine if it would be optimal for fisherman to purchase crop insurance. An important input into the fair insurance premium estimation is the yield distribution. Sherrick et al. estimated alternative yield distributions to evaluate traditional crop insurance. However, no one has looked at the yield distributions for the Dungeness crab nor explored possible crop insurance. Much of the past literature for the fishing industry has focused on production functions, cost function models, and optimal catching yields for specific fish species. Moreover, most research has focused on the endangered commercial ocean species such as tuna and swordfish. Data and Methodology This research collects the annual landing data including metric tons, pounds, and price per pound from NOAA's National Marine Fisheries Service (NOAA Fisheries Service) to analyze the yield distributions of Dungeness crab in California, Oregon, Washington, and Alaska from 1950 to 2009. Dickey Fuller test is conducted for each state to test if the data is stationary. The Durbin-Watson test was used to make sure the data did not have autocorrelation problems. We find that the detrended data has positive Skewness contrary to traditional crop yield data. The positive Skewness indicates that the tail on the right sides is longer than the left side and the mass of the distribution is concentrated on the left. It also has relatively few high values. The candidate distributions used include normal, Gamma, Weibull, logistic, lognormal, and loglogistic distributions. The fitted distributions are compared with formal goodness- of- fit tests including Chi-Square, Anderson-Darling, and Kolmogorov-Smirnov. The loglogistic distribution is best to estimate the yield losses of Alaska, Oregon, and California respectively while the logistic is best for Washington. The Gamma and normal distribution are the worst for the four states. Actual Production History (APH) policies insure crop producers against yield losses due to natural causes. After Just and Weninger found that crop yield losses were nonnormally distributed, many agricultural researchers use parametric (Goodwin and Ker) and nonparametric distributions (Sherrick et al) and the insured price to estimate the insurance premium. The premium refers to the periodic payment made on the insurance policy. When the yields are below the insured level (the predicted level each year), the insurance company has to pay indemnities to the producers to compensate them for their losses. Our study uses different parametric distributions to forecast the crab yields. Along with the yield distributions and yield forecasts, we assume that the crop insurance insures up to 80% of the yield distribution. We also assume that the insured price is the predicted price per pound for 2010 (since the price model are Pth-order autoregressive (AR(p)) processes) to estimate the fair insurance premium. The insured prices per pound of the four states from north to south are 2.39, 1.99 respectively. If the random value (that the realized yields fall below the guaranteed yields) generated by the best distributions which may generate different parametric value for the four states falls below zero, it will means that the fisherman suffer yield losses, and that the insurance company has to compensate the fishermen’s revenue. The insurance company pays the fishermen the dollars that the insured price times 80% of the yield that the fishermen suffer from loss. The indemnities will be either zero or positive. Next, we adopt Latin hypercube sampling (LHS) to simulate the indemnities 500 times to calculate the average indemnities. If we don’t consider the capital and administration fees of the insurance company, the average indemnities will be the actuarially fair insurance premium. The average indemnity and thus the actuarially fair premiums of the overall crab industry are 702,344, 3,470,998 one year for the all ships in Alaska, Washington, Oregon, and California respectively. Unlike traditional crop insurance that estimates the premium per acre, we use the total premium shared by all fishing vessels in the state and account for the total tons that the fishing vessels load because the crabs and the fishing vessel move everywhere. After simulated, half of the time the insurance company must pay indemnities. To avoid the high risk of yield losses and uncertainty, the existence of insurance is necessary to protect the fishermen’s revenue. Finally, we will try to use non-parametric method to estimate the fair premium and compare the results of the parametric and non-parametric distributions for the rigorous study. We will also estimate the potential welfare gain of fishermen from this insurance policy.Dungeness Crab, Fair Insurance Premium, Simulation, Agricultural and Food Policy, Agricultural Finance, Risk and Uncertainty,
Coordinated Multicasting with Opportunistic User Selection in Multicell Wireless Systems
Physical layer multicasting with opportunistic user selection (OUS) is
examined for multicell multi-antenna wireless systems. By adopting a two-layer
encoding scheme, a rate-adaptive channel code is applied in each fading block
to enable successful decoding by a chosen subset of users (which varies over
different blocks) and an application layer erasure code is employed across
multiple blocks to ensure that every user is able to recover the message after
decoding successfully in a sufficient number of blocks. The transmit signal and
code-rate in each block determine opportunistically the subset of users that
are able to successfully decode and can be chosen to maximize the long-term
multicast efficiency. The employment of OUS not only helps avoid
rate-limitations caused by the user with the worst channel, but also helps
coordinate interference among different cells and multicast groups. In this
work, efficient algorithms are proposed for the design of the transmit
covariance matrices, the physical layer code-rates, and the target user subsets
in each block. In the single group scenario, the system parameters are
determined by maximizing the group-rate, defined as the physical layer
code-rate times the fraction of users that can successfully decode in each
block. In the multi-group scenario, the system parameters are determined by
considering a group-rate balancing optimization problem, which is solved by a
successive convex approximation (SCA) approach. To further reduce the feedback
overhead, we also consider the case where only part of the users feed back
their channel vectors in each block and propose a design based on the balancing
of the expected group-rates. In addition to SCA, a sample average approximation
technique is also introduced to handle the probabilistic terms arising in this
problem. The effectiveness of the proposed schemes is demonstrated by computer
simulations.Comment: Accepted by IEEE Transactions on Signal Processin
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