Climate Change, One Health and Mercury

Climate change is occurring on both regional and global scales. The use and global distribution of toxic metals is increasing and affecting environmental, animal and human health as a result of air, water and food contamination. Mercury (Hg) in major forms Hg°, Hg2+ and methyl mercury (CH3Hg+) are increasingly available around the globe. Both metal and organic contaminants are impacting the health of all species on the planet. Mercury is an example of a metal that can cause or aggravate a disease state, for example, diabetes. Habitat stewardship is needed to maintain a healthy system, and selecting a keystone species as a bio indicator to monitor changes in contaminant levels over time and space is essential. Mercury can be used to monitor the flow of toxics through the food system. The structural organization of food webs and their sensitivity to disturbances are relevant to predicting the fate of Hg bioavailability related to climate change. Hg needs to be monitored across many ecosystems because it impacts not only human health but also the health of the plants and animals. Monitoring studies are needed to identify changes related to climate change. Increased precipitation and sea level rise will result in greater mercury mobility into the coastal and terrestrial food webs

Evidence from K2 for rapid rotation in the descendant of an intermediate-mass star

Using patterns in the oscillation frequencies of a white dwarf observed by K2, we have measured the fastest rotation rate, 1.13(02) hr, of any isolated pulsating white dwarf known to date. Balmer-line fits to follow-up spectroscopy from the SOAR telescope show that the star (SDSSJ0837+1856, EPIC 211914185) is a 13,590(340) K, 0.87(03) solar-mass white dwarf. This is the highest mass measured for any pulsating white dwarf with known rotation, suggesting a possible link between high mass and fast rotation. If it is the product of single-star evolution, its progenitor was a roughly 4.0 solar-mass main-sequence B star; we know very little about the angular momentum evolution of such intermediate-mass stars. We explore the possibility that this rapidly rotating white dwarf is the byproduct of a binary merger, which we conclude is unlikely given the pulsation periods observed.Comment: 5 pages, 4 figure, 1 table; accepted for publication in The Astrophysical Journal Letter

Direct Minimization Generating Electronic States with Proper Occupation Numbers

We carry out the direct minimization of the energy functional proposed by Mauri, Galli and Car to derive the correct self-consistent ground state with fractional occupation numbers for a system degenerating at the Fermi level. As a consequence, this approach enables us to determine the electronic structure of metallic systems to a high degree of accuracy without the aid of level broadening of the Fermi-distribution function. The efficiency of the method is illustrated by calculating the ground-state energy of C$_2$ and Si$_2$ molecules and the W(110) surface to which a tungsten adatom is adsorbed.Comment: 4 pages, 4 figure

Social identity and environmental concern: the importance of contextual effects

This study draws on social identity theory to explain differences in individual support for environmental protection, a conative component of environmental concern. It argues that an individual’s identification with higher social units—community, nation, and world—strengthens its in-group solidarity and empathy and, in consequence, its readiness to protect the environment benefitting the in-group’s welfare. The study hypothesizes that country-level manifestations of social identity (1) lift individuals’ support for environmental protection above the level that their own social identity suggests (elevator effect), and (2) reinforce the effect of individuals’ social identity on their support for environmental protection (amplifier effect). Using a sample of over 30,000 individuals located in 38 countries around the world, the study finds strong evidence for the two contextual effects. The findings indicate that social identity plays an important role not just as an individual attribute but also as a central component of culture in fostering environmental concern

White Dwarf Rotation as a Function of Mass and a Dichotomy of Mode Linewidths: Kepler Observations of 27 Pulsating DA White Dwarfs Through K2 Campaign 8

We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs (DAVs, a.k.a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (>75 days) and duty cycle (>90%). The space-based photometry reveals pulsation properties previously inaccessible to ground-based observations. We observe a sharp dichotomy in oscillation mode linewidths at roughly 800 s, such that white dwarf pulsations with periods exceeding 800 s have substantially broader mode linewidths, more reminiscent of a damped harmonic oscillator than a heat-driven pulsator. Extended Kepler coverage also permits extensive mode identification: We identify the spherical degree of 61 out of 154 unique radial orders, providing direct constraints of the rotation period for 20 of these 27 DAVs, more than doubling the number of white dwarfs with rotation periods determined via asteroseismology. We also obtain spectroscopy from 4m-class telescopes for all DAVs with Kepler photometry. Using these homogeneously analyzed spectra we estimate the overall mass of all 27 DAVs, which allows us to measure white dwarf rotation as a function of mass, constraining the endpoints of angular momentum in low- and intermediate-mass stars. We find that 0.51-to-0.73-solar-mass white dwarfs, which evolved from 1.7-to-3.0-solar-mass ZAMS progenitors, have a mean rotation period of 35 hr with a standard deviation of 28 hr, with notable exceptions for higher-mass white dwarfs. Finally, we announce an online repository for our Kepler data and follow-up spectroscopy, which we collect at http://www.k2wd.org.Comment: 33 pages, 31 figures, 5 tables; accepted for publication in ApJS. All raw and reduced data are collected at http://www.k2wd.or

ac-Field-Controlled Anderson Localization in Disordered Semiconductor Superlattices

An ac field, tuned exactly to resonance with the Stark ladder in an ideal tight binding lattice under strong dc bias, counteracts Wannier-Stark localization and leads to the emergence of extended Floquet states. If there is random disorder, these states localize. The localization lengths depend non-monotonically on the ac field amplitude and become essentially zero at certain parameters. This effect is of possible relevance for characterizing the quality of superlattice samples, and for performing experiments on Anderson localization in systems with well-defined disorder.Comment: 10 pages, Latex; figures available on request from [email protected]

Solution of the relativistic Dirac-Hulthen problem

The one-particle three-dimensional Dirac equation with spherical symmetry is solved for the Hulthen potential. The s-wave relativistic energy spectrum and two-component spinor wavefunctions are obtained analytically. Conforming to the standard feature of the relativistic problem, the solution space splits into two distinct subspaces depending on the sign of a fundamental parameter in the problem. Unique and interesting properties of the energy spectrum are pointed out and illustrated graphically for several values of the physical parameters. The square integrable two-component wavefunctions are written in terms of the Jacobi polynomials. The nonrelativistic limit reproduces the well-known nonrelativistic energy spectrum and results in Schrodinger equation with a "generalized" three-parameter Hulthen potential, which is the sum of the original Hulthen potential and its square.Comment: 13 pages, 3 color figure

Core crystallization and pile-up in the cooling sequence of evolving white dwarfs

White dwarfs are stellar embers depleted of nuclear energy sources that cool over billions of years. These stars, which are supported by electron degeneracy pressure, reach densities of 10^7 grams per cubic centimetre in their cores. It has been predicted that a first-order phase transition occurs during white-dwarf cooling, leading to the crystallization of the non-degenerate carbon and oxygen ions in the core, which releases a considerable amount of latent heat and delays the cooling process by about one billion years. However, no direct observational evidence of this effect has been reported so far. Here we report the presence of a pile-up in the cooling sequence of evolving white dwarfs within 100 parsecs of the Sun, determined using photometry and parallax data from the Gaia satellite. Using modelling, we infer that this pile-up arises from the release of latent heat as the cores of the white dwarfs crystallize. In addition to the release of latent heat, we find strong evidence that cooling is further slowed by the liberation of gravitational energy from element sedimentation in the crystallizing cores. Our results describe the energy released by crystallization in strongly coupled Coulomb plasmas, and the measured cooling delays could help to improve the accuracy of methods used to determine the age of stellar populations from white dwarfs

Impact of Habitual Water Intake on Muscle Quality and Total Body Water-A Pilot Study

Proper hydration is essential for critical health and performance functions, such as muscle function and body fluid balance. The effect of acute hydration status has been studied on health and muscle performance; however, the effect of habitual water intake on muscle quality and total body water between high and low consumption has not been examined. PURPOSE: To determine the impact of habitual water intake on muscle quality and total body water. METHODS: Eleven women (age: 27.6±7.9 years; mass: 60.3±10.8 kg) provided a five-day dietary food log to categorize them into HIGH or LOW daily total water intake (TWI). TWI values \u3e2.5-3.3 L/day (HIGH) or \u3c 0.7-1.6 L/day (LOW) were used to determine groups. Bioelectrical impedance analysis (BIA) and ultrasound images were obtained to assess overall muscle quality and total body fluid balance between the two groups. Analysis of ultrasound images using ImageJ determined length (cm), cross-sectional area (CSA), and muscle quality through echo intensity (EI) of the participant’s right and left rectus femoris (RF). An independent sample T-Test and effect sizes (ES) were used to assess differences between HIGH and LOW. RESULTS: Due to this study being a pilot study, there was no significant differences in right RF length between LOW (1.44±0.22 cm) and HIGH (1.22±0.24 cm, p=0.153) with a large effect size of (ES=0.98). There were no significant differences in left RF length (p=0.861) between HIGH (1.46±0.28 cm) and LOW (1.42±0.32) groups with a trivial effect size (ES=0.11). Right RF CSA had non-significant differences between LOW (3.72±1.18 cm2) and HIGH (2.95±1.05 cm2, p=0.309) with medium effect (ES=0.68). There were no differences in CSA-left between HIGH (3.63 ± 1.06 cm) and LOW (3.83±1.44, p=0.816, ES=0.15). Right RF muscle quality also had a medium effect size (ES=0.78) between HIGH (135.30±21.82 A.U) and LOW (117.71±23.10 A.U). Muscle quality of the left RF had a small effect size (ES=0.26) between LOW (118.29±22.18 A.U) and HIGH (125.97±39.47 A.U, p=0.684). While there was no statistical difference due to the power (p=0.163), total body water (TBW) percentage (%) was greater in HIGH (53.9±1.5%) compared to LOW (50.6±5.4%, ES= 0.75) with medium effects. HIGH and LOW demonstrated no statistical difference (p=0.579) with a small effect size (ES=0.36) between ECF% and ICF%, respectively (41.00±0.72%, 41.39±1.20%; 59.00±0.72%, 58.61±1.20%). CONCLUSION: Despite no significant differences, based on ES, HIGH habitual water intake increases TBW% than LOW. Further data must be collected to draw definitive conclusions; however, these results suggest skeletal muscle quality is high with LOW habitual water intake