Heat capacity of hafnium mononitride from temperatures of 5 to 350 K: An estimation procedure

Measurements of the heat capacity by quasi-adiabatic, intermittent energy increments from 5 to 350 K show small high heat-capacity anomalies near 7 and 10 K which are attributed to superconducting transitions seen by magnetic measurements on the same carefully synthesized and well-characterized sample of (Hf 0.934 Zr 0.057 )(N 0.97 ). Although no previous heat capacity measurements over the cryogenic region are known, the estimated 298.15 K standard entropy values ( S/R ) vary in the literature from about 200 per cent higher to 5 per cent lower than our measured value of (5.28±0.01)R −1 when the formula is represented as above. A simple scheme to represent and predict values based on both molar volumes and atomic masses for related materials is presented which seems more reliable on a limited sample than do others despite the intrusion of lanthanide contraction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43145/1/10973_2004_Article_400648.pd

Modeling Sub- and Super-ambient Heat Capacities of the Group Iva Compounds Despite the Lanthanide Contraction

This paper is concerned with the estimation of heat capacities in the IVA 3d-transition element compounds using especially Zr and Hf compounds as examples. Most prediction schemes routinely tacitly assume that volumes and masses trend ‘in parallel’. However, the lanthanide contraction here ensures for ZrX/HfX systems — and generally elsewhere — that this is not so in this portion of the periodic table. Available methods such as Latimer's, Volumetric Priority, Komada-Westrum, Grimvall's, and Sommers' are compared on IVA elements and compounds. Only the Sommers approach has volumetric input. It provides the best prediction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43144/1/10973_2004_Article_250156.pd

Enhanced mesoscopic fluctuations in the crossover between random matrix ensembles

In random-matrix ensembles that interpolate between the three basic ensembles (orthogonal, unitary, and symplectic), there exist correlations between elements of the same eigenvector and between different eigenvectors. We study such correlations, using a remarkable correspondence between the interpolating ensembles late in the crossover and a basic ensemble of finite size. In small metal grains or semiconductor quantum dots, the correlations between different eigenvectors lead to enhanced fluctuations of the electron-electron interaction matrix elements which become parametrically larger than the non-universal fluctuations.Comment: 4 pages, RevTeX; 3 figure

Large Deviations of the Maximum Eigenvalue in Wishart Random Matrices

We compute analytically the probability of large fluctuations to the left of the mean of the largest eigenvalue in the Wishart (Laguerre) ensemble of positive definite random matrices. We show that the probability that all the eigenvalues of a (N x N) Wishart matrix W=X^T X (where X is a rectangular M x N matrix with independent Gaussian entries) are smaller than the mean value =N/c decreases for large N as $\sim \exp[-\frac{\beta}{2}N^2 \Phi_{-}(\frac{2}{\sqrt{c}}+1;c)]$, where \beta=1,2 correspond respectively to real and complex Wishart matrices, c=N/M < 1 and \Phi_{-}(x;c) is a large deviation function that we compute explicitly. The result for the Anti-Wishart case (M < N) simply follows by exchanging M and N. We also analytically determine the average spectral density of an ensemble of constrained Wishart matrices whose eigenvalues are forced to be smaller than a fixed barrier. The numerical simulations are in excellent agreement with the analytical predictions.Comment: Published version. References and appendix adde

TeV Particle Astrophysics II: Summary comments

A unifying theme of this conference was the use of different approaches to understand astrophysical sources of energetic particles in the TeV range and above. In this summary I review how gamma-ray astronomy, neutrino astronomy and (to some extent) gravitational wave astronomy provide complementary avenues to understanding the origin and role of high-energy particles in energetic astrophysical sources.Comment: 6 pages, 4 figures; Conference summary talk for "TeV Particle Astrophysics II" at University of Wisconsin, Madison, 28-31 August 200

Multiple Group IRT Measurement Invariance Analysis of the Forms of Self-Criticising/Attacking and Self-Reassuring Scale in Thirteen International Samples

The purpose of this study was to examine the measurement invariance of the Forms of Self-Criticising/Attacking & Self-Reassuring Scale (FSCRS) in terms of Item Response Theory differential test functioning in thirteen distinct samples (N = 7714) from twelve different countries. We assessed differential test functioning for the three FSCRS subscales, Inadequate-Self, Hated-Self and Reassured-Self separately. 32 of the 78 pairwise comparisons between samples for Inadequate-Self, 42 of the 78 pairwise comparisons for Reassured-Self and 54 of the 78 pairwise comparisons for Hated-Self demonstrated no differential test functioning, i.e. measurement invariance. Hated-Self was the most invariant of the three subscales, suggesting that self-hatred is similarly perceived across different cultures. Nonetheless, all three subscales of FSCRS are sensitive to cross-cultural differences. Considering the possible cultural and linguistic differences in the expression of self-criticism and self-reassurance, future analyses of the meanings and connotations of these constructs across the world are necessary in order to develop or tailor a scale which allows cross-cultural comparisons of various treatment outcomes related to self-criticism

Statistical distribution of quantum entanglement for a random bipartite state

We compute analytically the statistics of the Renyi and von Neumann entropies (standard measures of entanglement), for a random pure state in a large bipartite quantum system. The full probability distribution is computed by first mapping the problem to a random matrix model and then using a Coulomb gas method. We identify three different regimes in the entropy distribution, which correspond to two phase transitions in the associated Coulomb gas. The two critical points correspond to sudden changes in the shape of the Coulomb charge density: the appearance of an integrable singularity at the origin for the first critical point, and the detachement of the rightmost charge (largest eigenvalue) from the sea of the other charges at the second critical point. Analytical results are verified by Monte Carlo numerical simulations. A short account of some of these results appeared recently in Phys. Rev. Lett. {\bf 104}, 110501 (2010).Comment: 7 figure

Composition of UHECR and the Pierre Auger Observatory Spectrum

We fit the recently published Pierre Auger ultra-high energy cosmic ray spectrum assuming that either nucleons or nuclei are emitted at the sources. We consider the simplified cases of pure proton, or pure oxygen, or pure iron injection. We perform an exhaustive scan in the source evolution factor, the spectral index, the maximum energy of the source spectrum Z E_{max}, and the minimum distance to the sources. We show that the Pierre Auger spectrum agrees with any of the source compositions we assumed. For iron, in particular, there are two distinct solutions with high and low E_{max} (e.g. 6.4 10^{20} eV and 2 10^{19} eV) respectively which could be distinguished by either a large fraction or the near absence of proton primaries at the highest energies. We raise the possibility that an iron dominated injected flux may be in line with the latest composition measurement from the Pierre Auger Observatory where a hint of heavy element dominance is seen.Comment: 19 pages, 6 figures (33 panels)- Uses iopart.cls and iopart12.clo- In version 2: addition of a few sentences and two reference

ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries.

This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors

The factor structure of the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen distinct populations

There is considerable evidence that self-criticism plays a major role in the vulnerability to and recovery from psychopathology. Methods to measure this process, and its change over time, are therefore important for research in psychopathology and well-being. This study examined the factor structure of a widely used measure, the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen nonclinical samples (N = 7510) from twelve different countries: Australia (N = 319), Canada (N = 383), Switzerland (N = 230), Israel (N = 476), Italy (N = 389), Japan (N = 264), the Netherlands (N = 360), Portugal (N = 764), Slovakia (N = 1326), Taiwan (N = 417), the United Kingdom 1 (N = 1570), the United Kingdom 2 (N = 883), and USA (N = 331). This study used more advanced analyses than prior reports: a bifactor item-response theory model, a two-tier item-response theory model, and a non-parametric item-response theory (Mokken) scale analysis. Although the original three-factor solution for the FSCRS (distinguishing between Inadequate-Self, Hated-Self, and Reassured-Self) had an acceptable fit, two-tier models, with two general factors (Self-criticism and Self-reassurance) demonstrated the best fit across all samples. This study provides preliminary evidence suggesting that this two-factor structure can be used in a range of nonclinical contexts across countries and cultures. Inadequate-Self and Hated-Self might not by distinct factors in nonclinical samples. Future work may benefit from distinguishing between self-correction versus shame-based self-criticism.Peer reviewe