The isotope composition of selenium in chondrites constrains the depletion mechanism of volatile elements in solar system materials

Solar nebula processes led to a depletion of volatile elements in different chondrite groups when compared to the bulk chemical composition of the solar system deduced from the Sun's photosphere. For moderately-volatile elements, this depletion primarily correlates with the element condensation temperature and is possibly caused by incomplete condensation from a hot solar nebula, evaporative loss from the precursor dust, and/or inherited from the interstellar medium. Element concentrations and interelement ratios of volatile elements do not provide a clear picture about responsible mechanisms. Here, the abundance and stable isotope composition of the moderately- to highly-volatile element Se are investigated in carbonaceous, ordinary, and enstatite chondrites to constrain the mechanism responsible for the depletion of volatile elements in planetary bodies of the inner solar system and to define a δ(82/78)Se value for the bulk solar system. The δ(82/78)Se of the studied chondrite falls are identical within their measurement uncertainties with a mean of −0.20±0.26‰ (2 s.d., n=14n=14, relative to NIST SRM 3149) despite Se abundance depletions of up to a factor of 2.5 with respect to the CI group. The absence of resolvable Se isotope fractionation rules out a kinetic Rayleigh-type incomplete condensation of Se from the hot solar nebula or partial kinetic evaporative loss on the precursor material and/or the parent bodies. The Se depletion, if acquired during partial condensation or evaporative loss, therefore must have occurred under near equilibrium conditions to prevent measurable isotope fractionation. Alternatively, the depletion and cooling of the nebula could have occurred simultaneously due to the continuous removal of gas and fine particles by the solar wind accompanied by the quantitative condensation of elements from the pre-depleted gas. In this scenario the condensation of elements does not require equilibrium conditions to avoid isotope fractionation. The results further suggest that the processes causing the high variability of Se concentrations and depletions in ordinary and enstatite chondrites did not involve any measurable isotope fractionation. Different degrees of element depletions and isotope fractionations of the moderately-volatile elements Zn, S, and Se in ordinary and enstatite chondrites indicate that their volatility is controlled by the thermal stabilities of their host phases and not by the condensation temperature under canonical nebular conditions.

A picture is worth a thousand words--the utility of 3D visualization illustrated by a case of survived pancreatic transection

It is one of the most important tasks of the forensic pathologist to explain the forensically relevant medical findings to medical non-professionals. However, it is often difficult to comment on the nature and potential consequences of organ injuries in a comprehensive way to individuals with limited knowledge of anatomy and physiology. This rare case of survived pancreatic transaction after kicks to the abdomen illustrates how the application of dedicated software programs for three-dimensional reconstruction can overcome these difficulties, allowing for clear and concise visualization of complex findings.

The complex clinical picture of side effects to biologicals

Biologicals are proteins used as drugs. Biologicals target clearly defined molecular structures, being part of established pathogenetic pathways. Therefore, their focused mode of action seems to render them superior to classic small molecular drugs regarding "off-target" adverse drug reactions (ADR). Nevertheless, the increasing use of biologicals for the treatment of different diseases has revealed partially unexpected adverse reactions. The often direct interaction of a biological with the immune system provides a clue to most side effects, which have consequently been subclassified, based on pathogenetic principles, into 5 subtypes named alpha, beta, gamma, delta, and epsilon, reflecting overstimulation (high cytokine values, type alpha), hypersensitivity (type beta), immune deviation (including immunodeficiency, type gamma), cross-reactivity (type delta), and nonimmune mediated side effects (type epsilon). This article presents typical clinical manifestations of these subtypes of ADR to biologicals, proposes general rules for treating them, and provides a scheme for a thorough allergological workup. This approach should help in future handling of these often very efficient drugs.

Seasonality as a core business of phenology

The best characteristics of phenological observations are their description of seasons and seasonal patterns. Specific phenological phases are used to define the beginning and the end of seasons that form phenological calendars. Phenological observations more closely capture the integrated seasonal rhythm than statistically derived means or thresholds from climate elements. They only provide approximate indicators of seasonal changes and cannot replace visible or directly measurable phenomena. Including abiotic observations such as the timing of frost, thawing, icing, snow and fog even provides seasonality descriptions beyond the vegetation period. The length and position of seasons within the year is a foundation for an integrated description of seasonality presented as a phenological season diagram. Phenological observations are the indispensable basis for an integral description of a seasonal classification and seasonality. A well designed phenological diagram could offer a comprehensive picture of the rhythm and amplitude of seasons.