Isotopic constraints on the origin of meteoritic organic matter

Salient features of the isotopic distribution of H, C and N in the organic material found in carbonaceous meteorites are noted. Most organic fractions are strongly enriched in D with respect to the D/H ratio characteristic of H2 in the protosolar system; substantial variations in C-13/C-12 ratio are found among different molecular species, with oxidised species tending to be C-13 enriched relative to reduced species; some homologous series reveal systematic decrease in C-13/C-12 with increasing C number; considerable variation in N-15/N-14 ratio is observed within organic matter, though no systematic pattern to its distribution has yet emerged; no interelement correlations have been observed between isotope enrichments for the different biogenic elements. The isotopic complexity echoes the molecular diversity observed in meteoritic organic matter and suggests that the organic matter was formed by multiple processes and/or from multiple sources. However, existence of a few systematic patterns points towards survival of isotopic signatures characteristic of one or more specific processes. The widespread D enrichment implies either survival of many species of interstellar molecule or synthesis from a reservoir containing a significant interstellar component. Several of the questions raised above can be addressed by more detailed determination of the distribution of the H, C and N isotopes among different well-characterized molecular fractions. Thus, the present study is aimed at discovering whether the different amino acids have comparable D enrichments, which would imply local synthesis from a D-enriched reservoir, or very viable D enrichments, which would imply survival of some interstellar amino acids. The same approach is also being applied to polycyclic aromatic hydrocarbons. Because the analytical technique employed (secondary ion mass spectrometry) can acquire data for all three isotopic systems from each molecular fraction, any presently obscured interelement isotopic correlation should also be revealed, which will aid in identifying pertinent synthetic processes

Primordial material in meteorites

Primordial is a term which applied to material that entered the solar system early and became incorporated into a meteorite without totally losing its identity. Identification of such material surviving in meteorites is so far solely through recognition of anomalous isotopic compositions of generally macroscopic entities contained within those meteorites. Isotopic anomalies are, by definition, isotopic compositions which differ from the canonical solar system abundances in ways which cannot be explained in terms of local processes such as mass dependent fractionation, cosmic ray induced spallation or decay of radionuclides. A comprehensive account of isotopic anomalies is impractical here, so it is necessary to be selective. Issues which are potentially addressable through the study of such primordial material are examined. Those issues will be illustrated with specific, but not exhaustive, examples

Correlates of unmet needs and psychological distress in adolescent and young adults who have a parent diagnosed with cancer.

Objective. Young people who have a parent with cancer experience elevated levels of psychological distress and unmet needs. In this study we examined the associations between demographics, cancer variables, and family functioning; and levels of distress and unmet needs amongst young people who have a parent diagnosed with cancer. Methods. Young people aged 12 -24 with a parent with cancer (n=255) completed the Offspring Cancer Needs Instrument (unmet needs), the Kessler-10 (distress), and the Family Relationship Index (family functioning), along with measures of demographics and cancer variables (such as: age, sex, time since cancer diagnosis). Variables associated with distress and unmet needs (including unmet need domains) were assessed using multiple linear regression. Results. Being female and older, having more unmet cancer needs and poorer family functioning was associated with increased distress. Having a father with cancer, a shorter time since diagnosis, and poor family functioning were associated with increased unmet needs. Family conflict and expressiveness were particularly important components of family functioning. Having a parent relapse with cancer was also associated with unmet needs in the domains of practical assistance, ‘time out’, and support from other young people who have been through something similar. Conclusions. Delineating factors associated with increased distress and unmet needs assists in identifying at risk young people allowing improved assessment and tailoring of support to improve the psychosocial outcomes of young people impacted by parental cancer.beyondblu

Structure-dependent exchange in the organic magnets Cu(II)Pc and Mn(II)Pc

We study exchange couplings in the organic magnets copper(II) phthalocyanine (Cu(II)Pc) and manganese(II) phthalocyanine (Mn(II)Pc) by a combination of Green's function perturbation theory and \textsl{ab initio} density-functional theory (DFT). Based on the indirect exchange model our perturbation-theory calculation of Cu(II)Pc qualitatively agrees with the experimental observations. DFT calculations performed on Cu(II)Pc dimer show a very good quantitative agreement with exchange couplings that we extract by using a global fitting for the magnetization measurements to a spin-1/2 Bonner-Fisher model. These two methods give us remarkably consistent trends for the exchange couplings in Cu(II)Pc when changing the stacking angles. The situation is more complex for Mn(II)Pc owing to the competition between super-exchange and indirect exchange.Comment: 13 pages,10 figures. To appear in Physical Review

Experimental study of pedestrian flow through a bottleneck

In this work the results of a bottleneck experiment with pedestrians are presented in the form of total times, fluxes, specific fluxes, and time gaps. A main aim was to find the dependence of these values from the bottleneck width. The results show a linear decline of the specific flux with increasing width as long as only one person at a time can pass, and a constant value for larger bottleneck widths. Differences between small (one person at a time) and wide bottlenecks (two persons at a time) were also found in the distribution of time gaps.Comment: accepted for publication in J. Stat. Mec

What to think of canine obesity? Emerging challenges to our understanding of human-animal health relationships.

The coincident and increasing occurrence of weight-related health problems in humans and canines in Western societies poses a challenge to our understanding of human–animal health relationships. More specifically, the epistemological and normative impetus provided by current approaches to shared health risks and chronic diseases in cohabiting human and animal populations does not account for causal continuities in the way that people and their pets live together. An examination of differences in medical responses to these conditions in human and pet dogs points to the existence of a distinct conceptual and ethical sphere for companion animal veterinary medicine. The disengagement of veterinary medicine for companion animals from human medicine has implications for our understanding what is required for health and disease prevention at the level of populations. This disengagement of companion animal veterinarians from family and preventive medicine, in particular, constrains professional roles, planning processes and, thereby, the potential for better-integrated responses to shared burdens of chronic conditions that increasingly affect the health and welfare of people and companion animals. Keywords: Human–Animal Relationships, Medical Epistemology, Companion Animal Welfare, Veterinary Ethics, Public Health Ethics, One HealthCanadian Institutes of Health Research, Open Operating Gran