Tracking Fish Lifetime Exposure to Mercury Using Eye Lenses

Mercury (Hg) uptake in fish is affected by diet, growth, and environmental factors such as primary productivity or oxygen regimes. Traditionally, fish Hg exposure is assessed using muscle tissue or whole fish, reflecting both loss and uptake processes that result in Hg bioaccumulation over entire lifetimes. Tracking changes in Hg exposure of an individual fish chronologically throughout its lifetime can provide novel insights into the processes that affect Hg bioaccumulation. Here we use eye lenses to determine Hg uptake at an annual scale for individual fish. We assess the widely distributed benthic round goby (Neogobius melanostomus) from the Baltic Sea, Lake Erie, and the St. Lawrence River. We aged layers of the eye lens using proportional relationships between otolith length at age and eye lens radius for each individual fish. Mercury concentrations were quantified using laser ablation inductively coupled plasma mass spectrometry. The eye lens Hg content revealed that Hg exposure increased with age in Lake Erie and the Baltic Sea but decreased with age in the St. Lawrence River, a trend not detected using muscle tissues. This novel methodology for measuring Hg concentration over time with eye lens chronology holds promise for quantifying how global change processes like increasing hypoxia affect the exposure of fish to Hg

A novel bifunctional oxygen GDE for alkaline secondary batteries

AbstractThis paper describes a novel procedure for the fabrication of a gas diffusion electrode (GDE) suitable for use as a bifunctional oxygen electrode in alkaline secondary batteries. The electrode is fabricated by pre-forming a PTFE-bonded nickel powder layer on a nickel foam substrate followed by deposition of NiCo2O4 spinel electrocatalyst by dip coating in a nitrate solution and thermal decomposition. The carbon-free composition avoids concerns over carbon corrosion at the potentials for oxygen evolution. The electrode shows acceptable overpotentials for both oxygen evolution and oxygen reduction at current densities up to 100mAcm−2. Stable performance during >100 successive, 1h oxygen reduction/evolution cycles at a current density of 20mAcm−2 in 8M NaOH at 333K was achieved

A novel bifunctional oxygen GDE for alkaline secondary batteries

This paper describes a novel procedure for the fabrication of a gas diffusion electrode (GDE) suitable for use as a bifunctional oxygen electrode in alkaline secondary batteries. The electrode is fabricated by pre-forming a PTFE-bonded nickel powder layer on a nickel foam substrate followed by deposition of NiCo2O4 spinel electrocatalyst by dip coating in a nitrate solution and thermal decomposition. The carbon-free composition avoids concerns over carbon corrosion at the potentials for oxygen evolution. The electrode shows acceptable overpotentials for both oxygen evolution and oxygen reduction at current densities up to 100 mA cm−2. Stable performance during >100 successive, 1 h oxygen reduction/evolution cycles at a current density of 20 mA cm−2 in 8 M NaOH at 333 K was achieved.European Commissio

The Pediatrician and Disaster Preparedness

Recent natural disasters and events of terrorism and war have heightened society's recognition of the need for emergency preparedness. In addition to the unique pediatric issues involved in general emergency preparedness, several additional issues related to terrorism preparedness must be considered, including the unique vulnerabilities of children to various agents as well as the limited availability of age- and weight-appropriate antidotes and treatments. Although children may respond more rapidly to therapeutic intervention, they are at the same time more susceptible to various agents and conditions and more likely to deteriorate if not monitored carefully.The challenge of dealing with the threat of terrorism, natural disasters, and public health emergencies in the United States is daunting not only for disaster planners but also for our medical system and health professionals of all types, including pediatricians. As part of the network of health responders, pediatricians need to be able to answer concerns of patients and families, recognize signs of possible exposure to a weapon of terror, understand first-line response to such attacks, and sufficiently participate in disaster planning to ensure that the unique needs of children are addressed satisfactorily in the overall process. Pediatricians play a central role in disaster and terrorism preparedness with families, children, and their communities. This applies not only to the general pediatrician but also to the pediatric medical subspecialist and pediatric surgical specialist. Families view pediatricians as their expert resource, and most of them expect the pediatrician to be knowledgeable in areas of concern. Providing expert guidance entails educating families in anticipation of events and responding to questions during and after actual events. It is essential that pediatricians educate themselves regarding these issues of emergency preparedness. For pediatricians, some information is currently available on virtually all of these issues in recently produced printed materials, at special conferences, in broadcasts of various types, and on the Internet. However, selecting appropriate, accurate sources of information and determining how much information is sufficient remain difficult challenges. Similarly, guidance is needed with respect to developing relevant curricula for medical students and postdoctoral clinical trainees

Recovery of Metastable Dense Bi Synthesized by Shock Compression

X-ray free electron laser (XFEL) sources have revolutionized our capability to study ultrafast material behavior. Using an XFEL, we revisit the structural dynamics of shock compressed bismuth, resolving the transition sequence on shock release in unprecedented details. Unlike previous studies that found the phase-transition sequence on shock release to largely adhere to the equilibrium phase diagram (i.e., Bi-V → Bi-III → Bi-II → Bi-I), our results clearly reveal previously unseen, non-equilibrium behavior at these conditions. On pressure release from the Bi-V phase at 5 GPa, the Bi-III phase is not formed but rather a new metastable form of Bi. This new phase transforms into the Bi-II phase which in turn transforms into a phase of Bi which is not observed on compression. We determine this phase to be isostructural with β-Sn and recover it to ambient pressure where it exists for 20 ns before transforming back to the Bi-I phase. The structural relationship between the tetragonal β-Sn phase and the Bi-II phase (from which it forms) is discussed. Our results show the effect that rapid compression rates can have on the phase selection in a transforming material and show great promise for recovering high-pressure polymorphs with novel material properties in the future

How are falls and fear of falling associated with objectively measured physical activity in a cohort of community-dwelling older men?

BACKGROUND: Falls affect approximately one third of community-dwelling older adults each year and have serious health and social consequences. Fear of falling (FOF) (lack of confidence in maintaining balance during normal activities) affects many older adults, irrespective of whether they have actually experienced falls. Both falls and fear of falls may result in restrictions of physical activity, which in turn have health consequences. To date the relation between (i) falls and (ii) fear of falling with physical activity have not been investigated using objectively measured activity data which permits examination of different intensities of activity and sedentary behaviour. METHODS: Cross-sectional study of 1680 men aged 71-92 years recruited from primary care practices who were part of an on-going population-based cohort. Men reported falls history in previous 12 months, FOF, health status and demographic characteristics. Men wore a GT3x accelerometer over the hip for 7 days. RESULTS: Among the 12% of men who had recurrent falls, daily activity levels were lower than among non-fallers; 942 (95% CI 503, 1381) fewer steps/day, 12(95% CI 2, 22) minutes less in light activity, 10(95% CI 5, 15) minutes less in moderate to vigorous PA [MVPA] and 22(95% CI 9, 35) minutes more in sedentary behaviour. 16% (n = 254) of men reported FOF, of whom 52% (n = 133) had fallen in the past year. Physical activity deficits were even greater in the men who reported that they were fearful of falling than in men who had fallen. Men who were fearful of falling took 1766(95% CI 1391, 2142) fewer steps/day than men who were not fearful, and spent 27(95% CI 18, 36) minutes less in light PA, 18(95% CI 13, 22) minutes less in MVPA, and 45(95% CI 34, 56) minutes more in sedentary behaviour. The significant differences in activity levels between (i) fallers and non-fallers and (ii) men who were fearful of falling or not fearful, were mediated by similar variables; lower exercise self-efficacy, fewer excursions from home and more mobility difficulties. CONCLUSIONS: Falls and in particular fear of falling are important barriers to older people gaining health benefits of walking and MVPA. Future studies should assess the longitudinal associations between falls and physical activity

A structural study of hcp and liquid iron under shock compression up to 275 GPa

We combine nanosecond laser shock compression with \emph{in-situ} picosecond X-ray diffraction to provide structural data on iron up to 275 GPa. We constrain the extent of hcp-liquid coexistence, the onset of total melt, and the structure within the liquid phase. Our results indicate that iron, under shock compression, melts completely by 258(8) GPa. A coordination number analysis indicates that iron is a simple liquid at these pressure-temperature conditions. We also perform texture analysis between the ambient body-centered-cubic (bcc) $\alpha$, and the hexagonal-closed-packed (hcp) high-pressure $\epsilon-$phase. We rule out the Rong-Dunlop orientation relationship (OR) between the $\alpha$ and $\epsilon-$phases. However, we cannot distinguish between three other closely related ORs: Burger's, Mao-Bassett-Takahashi, and Potter's OR. The solid-liquid coexistence region is constrained from a melt onset pressure of 225(3) GPa from previously published sound speed measurements and full melt (246.5(1.8)-258(8) GPa) from X-ray diffraction measurements, with an associated maximum latent heat of melting of 623 J/g. This value is lower than recently reported theoretical estimates and suggests that the contribution to the earth's geodynamo energy budget from heat release due to freezing of the inner core is smaller than previously thought. Melt pressures for these nanosecond shock experiments are consistent with gas gun shock experiments that last for microseconds, indicating that the melt transition occurs rapidly

Design and Status of the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): An Interferometer at the Edge of Space

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infraredinterferometer designed to fly on a high altitude balloon. BETTII uses a double-Fourier Michelson interferometer tosimultaneously obtain spatial and spectral information on science targets; the long baseline permits subarcsecond angular resolution, a capability unmatched by other far-infrared facilities. Here, we present key aspects of the overall design of the mission and provide an overview of the current status of the project. We also discuss briefly the implications of this experiment for future space-based far-infrared interferometers

Bottom pressure signals at the TAG deep-sea hydrothermal field : evidence for short-period, flow-induced ground deformation

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 36 (2009): L19301, doi:10.1029/2009GL040006.Bottom pressure measurements acquired from the TAG hydrothermal field on the Mid-Atlantic Ridge (26°N) contain clusters of narrowband spectral peaks centered at periods from 22 to 53.2 minutes. The strongest signal at 53.2 min corresponds to 13 mm of water depth variation. Smaller, but statistically significant, signals were also observed at periods of 22, 26.5, 33.4, and 37.7 min (1–4 mm amplitude). These kinds of signals have not previously been observed in the ocean, and they appear to represent vertical motion of the seafloor in response to hydrothermal flow - similar in many ways to periodic terrestrial geysers. We demonstrate that displacements of 13 mm can be produced by relatively small flow-induced pressures (several kPa) if the source region is less than ∼100 m below the seafloor. We suggest that the periodic nature of the signals results from a non-linear relationship between fluid pore pressure and crustal permeability