On Silicon Carbide Grains as the Carrier of the 21 Micron Emission Feature in Post-Asymptotic Giant Branch Stars

The mysterious 21mu emission feature seen in 12 proto-planetary nebulae (PPNe) remains unidentified since its first detection in 1989. Over a dozen of candidate materials have been proposed within the past decade, but none of them has received general acceptance. Very recently, silicon carbide (SiC) grains with impurities were suggested to be the carrier of this enigmatic feature, based on recent laboratory data that doped SiC grains exhibit a resonance at \~21mu. This proposal gains strength from the fact that SiC is a common dust species in carbon-rich circumstellar envelopes. However, SiC dust has a strong vibrational band at ~11.3mu. We show in this Letter that in order to be consistent with the observed flux ratios of the 11.3mu feature to the 21mu feature, the band strength of the 21mu resonance has to be very strong, too strong to be consistent with current laboratory measurements. But this does not yet readily rule out the SiC hypothesis since recent experimental results have demonstrated that the 21mu resonance of doped SiC becomes stronger as the C impurity increases. Further laboratory measurements of SiC dust with high fractions of C impurity are urgently needed to test the hypothesis of SiC as the carrier of the 21mu feature.Comment: 14 pages, 3 figures, accepted for publication in ApJ

Risk of criminal victimisation in outpatients with common mental health disorders

Crime victimisation is a serious problem in psychiatric patients. However, research has focused on patients with severe mental illness and few studies exist that address victimisation in other outpatient groups, such as patients with depression. Due to large differences in methodology of the studies that address crime victimisation, a comparison of prevalence between psychiatric diagnostic groups is hard to make. Objectives of this study were to determine and compare one-year prevalence of violent and non-violent criminal victimisation among outpatients from different diagnostic psychiatric groups and to examine prevalence differences with the general population.Criminal victimisation prevalence was measured in 300 outpatients living in Amsterdam, The Netherlands. Face-to-face interviews were conducted with outpatients with depressive disorder (n = 102), substance use disorder (SUD, n = 106) and severe mental illness (SMI, n = 92) using a National Crime Victimisation Survey, and compared with a matched general population sample (n = 10865).Of all outpatients, 61% reported experiencing some kind of victimisation over the past year; 33% reported violent victimisation (3.5 times more than the general population) and 36% reported property crimes (1.2 times more than the general population). Outpatients with depression (67%) and SUD (76%) were victimised more often than SMI outpatients (39%). Younger age and hostile behaviour were associated with violent victimisation, while being male and living alone were associated with non-violent victimisation. Moreover, SUD was associated with both violent and non-violent victimisation.Outpatients with depression, SUD, and SMI are at increased risk of victimisation compared to the general population. Furthermore, our results indicate that victimisation of violent and non-violent crimes is more common in outpatients with depression and SUD than in outpatients with SMI living independently in the community

Serum IL-15 in patients with early systemic sclerosis: a potential novel marker of lung disease

The pathogenesis of systemic sclerosis (SSc) is characterized by autoimmunity, vasculopathy and fibrosis. IL-15 is a pleiotropic cytokine that has impact on immune, vascular and connective tissue cells. We therefore investigated IL-15 in the circulation of patients with early SSc and explored possible associations of serum IL-15 with vasculopathy and fibrosis. Serum levels of IL-15 were analysed in 63 consecutive patients with SSc of disease duration less than 4 years and without disease-modifying treatment. Thirty-three age-matched healthy control individuals were enrolled. Serum IL-15 levels were increased in the sera of SSc patients compared with that of healthy control individuals (P < 0.01). Serum IL-15 levels correlated with impaired lung function, assessed both by the vital capacity (P < 0.05) and by the carbon monoxide diffusion capacity (P < 0.05). The association between IL-15 and the vital capacity remained after multiple linear regression analysis. Patients with intermediate serum IL-15 levels had a higher prevalence of increased systolic pulmonary pressure compared with patients with either low or high serum IL-15 levels (P < 0.05). Moreover, increased serum IL-15 levels were associated with a reduced nailfold capillary density in multivariable logistic regression analysis (P < 0.01). Serum IL-15 levels also correlated inversely with the systolic blood pressure (P < 0.01). We conclude that IL-15 is associated with fibrotic as well as vascular lung disease and vasculopathy in early SSc. IL-15 may contribute to the pathogenesis of SSc. IL-15 could also be a candidate biomarker for pulmonary involvement and a target for therapy in SSc

Irreversible impacts of heat on the emissions of monoterpenes, sesquiterpenes, phenolic BVOC and green leaf volatiles from several tree species

Climate change will induce extended heat waves to parts of the vegetation more frequently. High temperatures may act as stress (thermal stress) on plants changing emissions of biogenic volatile organic compounds (BVOCs). As BVOCs impact the atmospheric oxidation cycle and aerosol formation, it is important to explore possible alterations of BVOC emissions under high temperature conditions. Applying heat to European beech, Palestine oak, Scots pine, and Norway spruce in a laboratory setup either caused the well-known exponential increases of BVOC emissions or induced irreversible changes of BVOC emissions. Considering only irreversible changes of BVOC emissions as stress impacts, we found that high temperatures decreased the &lt;i&gt;de novo&lt;/i&gt; emissions of monoterpenes, sesquiterpenes and phenolic BVOC. This behaviour was independent of the tree species and whether the &lt;i&gt;de novo&lt;/i&gt; emissions were constitutive or induced by biotic stress. &lt;br&gt;&lt;br&gt; In contrast, application of thermal stress to conifers amplified the release of monoterpenes stored in resin ducts of conifers and induced emissions of green leaf volatiles. In particular during insect attack on conifers, the plants showed &lt;i&gt;de novo&lt;/i&gt; emissions of sesquiterpenes and phenolic BVOCs, which exceeded constitutive monoterpene emissions from pools. The heat-induced decrease of &lt;i&gt;de novo&lt;/i&gt; emissions was larger than the increased monoterpene release caused by damage of resin ducts. For insect-infested conifers the net effect of thermal stress on BVOC emissions could be an overall decrease. &lt;br&gt;&lt;br&gt; Global change-induced heat waves may put hard thermal stress on plants. If so, we project that BVOC emissions increase is more than predicted by models only in areas predominantly covered with conifers that do not emit high amounts of sesquiterpenes and phenolic BVOCs. Otherwise overall effects of high temperature stress will be lower increases of BVOC emissions than predicted by algorithms that do not consider stress impacts

Von Willebrand factor propeptide as a marker of disease activity in systemic sclerosis (scleroderma)

In 44 consecutive patients with systemic sclerosis (SSc), plasma concentrations of von Willebrand factor (vWf) were higher than those of the vWf propeptide, but the propeptide showed less variability within patient subgroups. Higher values of the propeptide were observed in patients with early pulmonary involvement. A closer correlation of the propeptide than of vWf to biochemical markers of activity was also evident. Our results suggest that the propeptide, despite a shorter circulating half-time and lower plasma concentrations than vWf, is more useful in the assessment of disease activity in SSc

Tacrolimus-induced nephrotoxicity and genetic variability:A review

Background: Calcineurin inhibition (CNI) is the mainstay of immunosuppressant therapy for most solid organ transplant patients. High tacrolimus levels are related with acute nephrotoxicity, but the relationship with chronic toxicity is less clear. Variation in disposition of tacrolimus is associated with genetic variation in CYP3A5. Hence, could genetic variation in CYP3A5 or other genes involved in tacrolimus disposition and effect be associated with a risk for tacrolimus-induced nephrotoxicity? To perform a review of the literature and to identify if genetic variation in CYP3A5 or other genes involved in tacrolimus disposition or effect may be associated with tacrolimus-induced nephrotoxicity and/or renal dysfunction in solid organ transplant recipients. Material/Methods: Pubmed/Medline, Embase and Google were searched from their inception till November 8th 2010 with the search terms 'tacrolimus', 'genetics', and 'nephrotoxicity' or 'renal dysfunction'. References of relevant articles were screened as well. Results: We identified 13 relevant papers. In kidney recipients, associations between donor ABCB1, recipient CCR5 genotype and tacrolimus-induced nephrotoxicity were found. CYP3A5 genotype studies in kidney recipients yielded contradictory results. In liver recipients, a possible association between recipient ACE, CYP3A5, ABCB1 and CYP2C8 genetic polymorphisms and tacrolimus-induced nephrotoxicity was suggested. In heart recipients, TGF-β genetic polymorphisms were associated with tacrolimus-induced nephrotoxicity. The quality of the studies varied considerably. Conclusions: Limited evidence suggests that variation in genes involved in pharmacokinetics (ABCB1 and CYP3A5) and pharmacodynamics (TGF-β, CYP2C8, ACE, CCR5) of tacrolimus may impact a transplant recipients' risk to develop tacrolimus-induced nephrotoxicity across different transplant organ groups.</p

The formation, properties and impact of secondary organic aerosol: current and emerging issues

Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed

Inbreeding Avoidance Influences the Viability of Reintroduced Populations of African Wild Dogs (Lycaon pictus)

The conservation of many fragmented and small populations of endangered African wild dogs (Lycaon pictus) relies on understanding the natural processes affecting genetic diversity, demographics, and future viability. We used extensive behavioural, life-history, and genetic data from reintroduced African wild dogs in South Africa to (1) test for inbreeding avoidance via mate selection and (2) model the potential consequences of avoidance on population persistence. Results suggested that wild dogs avoided mating with kin. Inbreeding was rare in natal packs, after reproductive vacancies, and between sibling cohorts (observed on 0.8%, 12.5%, and 3.8% of occasions, respectively). Only one of the six (16.7%) breeding pairs confirmed as third-order (or closer) kin consisted of animals that were familiar with each other, while no other paired individuals had any prior association. Computer-simulated populations allowed to experience inbreeding had only a 1.6% probability of extinction within 100 years, whereas all populations avoiding incestuous matings became extinct due to the absence of unrelated mates. Populations that avoided mating with first-order relatives became extinct after 63 years compared with persistence of 37 and 19 years for those also prevented from second-order and third-order matings, respectively. Although stronger inbreeding avoidance maintains significantly more genetic variation, our results demonstrate the potentially severe demographic impacts of reduced numbers of suitable mates on the future viability of small, isolated wild dog populations. The rapid rate of population decline suggests that extinction may occur before inbreeding depression is observed