Crystallization of classical multi-component plasmas

We develop a method for calculating the equilibrium properties of the liquid-solid phase transition in a classical, ideal, multi-component plasma. Our method is a semi-analytic calculation that relies on extending the accurate fitting formulae available for the one-, two-, and three-component plasmas to the case of a plasma with an arbitrary number of components. We compare our results to those of Horowitz, Berry, & Brown (Phys. Rev. E, 75, 066101, 2007), who use a molecular dynamics simulation to study the chemical properties of a 17-species mixture relevant to the ocean-crust boundary of an accreting neutron star, at the point where half the mixture has solidified. Given the same initial composition as Horowitz et al., we are able to reproduce to good accuracy both the liquid and solid compositions at the half-freezing point; we find abundances for most species within 10% of the simulation values. Our method allows the phase diagram of complex mixtures to be explored more thoroughly than possible with numerical simulations. We briefly discuss the implications for the nature of the liquid-solid boundary in accreting neutron stars.Comment: 14 pages, 5 figures, submitted to Phys. Rev.

Model Atmospheres for X-ray Bursting Neutron Stars

The hydrogen and helium accreted by X-ray bursting neutron stars is periodically consumed in runaway thermonuclear reactions that cause the entire surface to glow brightly in X-rays for a few seconds. With models of the emission, the mass and radius of the neutron star can be inferred from the observations. By simultaneously probing neutron star masses and radii, X-ray bursts are one of the strongest diagnostics of the nature of matter at extremely high densities. Accurate determinations of these parameters are difficult, however, due to the highly non-ideal nature of the atmospheres where X-ray bursts occur. Observations from X-ray telescopes such as RXTE and NuStar can potentially place strong constraints on nuclear matter once uncertainties in atmosphere models have been reduced. Here we discuss current progress on modeling atmospheres of X-ray bursting neutron stars and some of the challenges still to be overcome.Comment: 25 pages, 14 figure

The Epsilon Calculus and Herbrand Complexity

Hilbert's epsilon-calculus is based on an extension of the language of predicate logic by a term-forming operator $\epsilon_{x}$. Two fundamental results about the epsilon-calculus, the first and second epsilon theorem, play a role similar to that which the cut-elimination theorem plays in sequent calculus. In particular, Herbrand's Theorem is a consequence of the epsilon theorems. The paper investigates the epsilon theorems and the complexity of the elimination procedure underlying their proof, as well as the length of Herbrand disjunctions of existential theorems obtained by this elimination procedure.Comment: 23 p

Klinefelter’s Syndrome: A fortuitously diagnosed by non-invasive prenatal testing

Case Report: A male infant born at 37 weeks gestation. His mother was a 29-year-old, gravida 4 para 3 woman. During her pregnancy she was curious as to the gender of the fetus and requested a non-invasive prenatal test (NIPT) rather than fetal ultrasound. The NIPT returned with a karyotype of XXY. The male infant was born vaginally with a birth weight of 2670 grams. Apgar scores were 8 and 9 at one and five minutes respectively. He was admitted to the newborn intensive care unit secondary to respiratory distress. He had no obvious dysmorphic features. He had normal appearing male genitalia with testes descended bilaterally. Fluorescent in situ hybridization and blood chromosomes confirmed an XXY karyotype. He was discharged from the newborn intensive care unit with follow up by genetic counselors and close monitoring for developmental delays Background: Klinefelter Syndrome (KS), a genetic disorder caused by the presence of supernumerary sex chromosomes. An additional X chromosome(s) and hypogonadism are the two defining features of KS. The excess of genes from the additional X chromosome drives the pathogenesis of the disease and distinguishing features of the affected individuals. The increase in the prevalence of prenatal testing has led to the earlier recognition of fetal chromosomal abnormalities. Early detection of KS through NIPT has given the family much needed information and allowing for early diagnosis and intervention, to promote the best outcome for the child. This case shows a patient that will benefit from the early diagnosis of a KS to implement early and timely interventions upon delivery and then later in the developing years. The neonate presented with no distinct, characteristic signs of KS, common in many individuals. Two findings, other than the NIPT results, weakly suggest any possible abnormality. Klinefelter neonates report mildly higher incidences of respiratory distress and low birth weight necessitating need for NICU admission. The underwhelming clinical presentation of the neonate shows that if NIPT wasn’t conducted, neither our patient nor his family would have known he was 47,XXY, until much later in life. IMPLICATIONS: Timely hormonal intervention is possible for our patient because of NIPT. This demonstrates a need of a standard KS screen. With the technology of NIPT advancing and improving in its ability to detect a variety of other conditions outside of the traditional autosomal aneuploidy, it should be considered a technique for screening for clinically silent conditions, such as mild KS phonotypes.https://digitalcommons.unmc.edu/chri_forum/1021/thumbnail.jp

Stigma, Substance Use, and Help-Seeking Attitudes Among Rural and Urban Individuals

The current study examined the differences between public stigma, self-stigma, substance use (i.e., alcohol and/or drugs), and attitudes toward psychological help-seeking among rural and urban individuals, and found meaningful differences in public stigma by alcohol use. Two hundred and sixty participants recruited via Amazon Mechanical Turk completed an online survey that included the Perceptions of Stigmatization by Others for Seeking Help scale, the Self-Stigma of Seeking Help scale, the Attitudes Toward Seeking Professional Psychological Help scale, the Alcohol Use Disorders Identification Test, the Drug Abuse Screening Test–10, and demographics. The authors found significant between-groups differences in public stigma for individuals who screened positive for an alcohol use disorder compared to those who used alcohol but did not meet the screening threshold. This finding suggested that there may be differences in stigmatization between individuals who only occasionally use alcohol and those with an alcohol use disorder. There were no significant differences in self-stigma or attitudes toward psychological help-seeking. Moreover, there were no significant between-groups differences based on DAST-10 scores for individuals who did not report drug use, individuals who reported using drugs, and those who screened positive for a substance use disorder on public stigma, self-stigma, or attitudes toward psychological help-seeking. Contrary to the authors’ hypothesis, the results did not demonstrate any significant differences between public stigma, self-stigma, or attitudes toward psychological help-seeking based on rurality (i.e., rural or urban). The authors highlight areas for future research focus and considerations when further examining stigma, substance use, and help-seeking attitudes among rural and urban individuals

Development of Thermal Insulation Materials Based on Silicate Using Non-Traditional Binders and Fillers

When insulation and rehabilitation of structures is important to use quality building materials with high utility value. One potentially interesting and promising groups of construction materials in this area are advanced, thermally insulating plaster silicate based. With the present trend reduction of energy consumption of building structures and reducing CO2 emissions to be developed capillary-active materials that are characterized by their low density, low thermal conductivity while maintaining good mechanical properties. The paper describes the results of research activities aimed at the development of thermal insulating and rehabilitation material ongoing at the Technical University in Brno, Faculty of Civil Engineering. The achieved results of this development will be the basis for subsequent experimental analysis of the influence of thermal and moisture loads developed on these materials

Successful Cessation Programs that Reduce Comorbidity May Explain Surprisingly Low Smoking Rates Among Hospitalized COVID-19 Patients

A recent, non-peer-reviewed meta-analysis suggests that smoking may reduce the risk of hospitalization with COVID-19 because the prevalence of smoking among hospitalized COVID-19 is less than that of the general population. However, there are alternative explanations for this phenomena based on (1) the failure to report, or accurately record, smoking history during emergency hospital admissions and (2) a pre-disposition to avoid smoking among COVID-19 patients with tobacco-related comorbidities (a type of “reverse” causation). For example, urine testing of hospitalized patients in Australia for cotinine showed that smokers were under-counted by 37% because incoming patients failed to inform staff about their smoking behavior. Face-to-face interviews can introduce bias into the responses to attitudinal and behavioral questions not present in the self-completion interviews typically used to measure smoking prevalence in the general population. Subjects in face-to-face interviews may be unwilling to admit socially undesirable behavior and attitudes under direct questioning. Reverse causation may also contribute to the difference between smoking prevalence in the COVID-19 and general population. Patients hospitalized with COVID-19 may be simply less prone to use tobacco than the general population. A potentially robust “reverse causation” hypothesis for reduced prevalence of smokers in the COVID-19 population is the enrichment of patients in that population with serious comorbidities that motivates them to quit smoking. We judge that this “smoking cessation” mechanism may account for a significant fraction of the reduced prevalence of smokers in the COVID-19 population. Testing this hypothesis will require a focused research program

Do Juvenile Nearctic River Otters (Lontra canadensis) Contribute to Fall Scent Marking?

We present photographic evidence in support of the hypothesis that juvenile Nearctic River Otters (Lontra canadensis) contribute to the observed fall peak in scent marking