Brown Carbon from Photo-Oxidation of Glyoxal and SO2 in Aqueous Aerosol

Aqueous-phase dark reactions during the co-oxidation of glyoxal and S(IV) were recently identified as a potential source of brown carbon (BrC). Here, we explore the effects of sunlight and oxidants on aqueous solutions of glyoxal and S(IV), and on aqueous aerosol exposed to glyoxal and SO2. We find that BrC is able to form in sunlit, bulk-phase, sulfite-containing solutions, albeit more slowly than in the dark. In more atmospherically relevant chamber experiments where suspended aqueous aerosol particles are exposed to gas-phase glyoxal and SO2, the formation of detectable amounts of BrC requires an OH radical source and occurs most rapidly after a cloud event. From these observations we infer that this photobrowning is caused by radical-initiated reactions as evaporation concentrates aqueous-phase reactants and aerosol viscosity increases. Positive-mode electrospray ionization mass spectrometric analysis of aerosol-phase products reveals a large number of CxHyOz oligomers that are reduced rather than oxidized (relative to glyoxal), with the degree of reduction increasing in the presence of OH radicals. This again suggests a radical-initiated redox mechanism where photolytically produced aqueous radical species trigger S(IV)–O2 auto-oxidation chain reactions, and glyoxal-S(IV) redox reactions especially if aerosol-phase O2 is depleted. This process may contribute to daytime BrC production and aqueous-phase sulfur oxidation in the atmosphere. The BrC produced, however, is about an order of magnitude less light-absorbing than wood smoke BrC at 365 nm

Brown Carbon Production by Aqueous-Phase Interactions of Glyoxal and SO2

Oxalic acid and sulfate salts are major components of aerosol particles. Here, we explore the potential for their respective precursor species, glyoxal and SO2, to form atmospheric brown carbon via aqueous-phase reactions in a series of bulk aqueous and flow chamber aerosol experiments. In bulk aqueous solutions, UV- and visible-light-absorbing products are observed at pH 3–4 and 5–6, respectively, with small but detectable yields of hydroxyquinone and polyketone products formed, especially at pH 6. Hydroxymethanesulfonate (HMS), C2, and C3 sulfonates are major products detected by electrospray ionization mass spectrometry (ESI-MS) at pH 5. Past studies have assumed that the reaction of formaldehyde and sulfite was the only atmospheric source of HMS. In flow chamber experiments involving sulfite aerosol and gas-phase glyoxal with only 1 min residence times, significant aerosol growth is observed. Rapid brown carbon formation is seen with aqueous aerosol particles at \u3e80% relative humidity (RH). Brown carbon formation slows at 50–60% RH and when the aerosol particles are acidified with sulfuric acid but stops entirely only under dry conditions. This chemistry may therefore contribute to brown carbon production in cloud-processed pollution plumes as oxidizing volatile organic compounds (VOCs) interact with SO2 and water

Detecting a conditional extrme value model

In classical extreme value theory probabilities of extreme events are estimated assuming all the components of a random vector to be in a domain of attraction of an extreme value distribution. In contrast, the conditional extreme value model assumes a domain of attraction condition on a sub-collection of the components of a multivariate random vector. This model has been studied in \cite{heffernan:tawn:2004,heffernan:resnick:2007,das:resnick:2008a}. In this paper we propose three statistics which act as tools to detect this model in a bivariate set-up. In addition, the proposed statistics also help to distinguish between two forms of the limit measure that is obtained in the model.Comment: 21 pages, 4 figure

J Musculoskelet Neuronal Interact

Long-term bed-rest is used to simulate the effect of spaceflight on the human body and test different kinds of countermeasures. The 2nd Berlin BedRest Study (BBR2-2) tested the efficacy of whole-body vibration in addition to high-load resisitance exercise in preventing bone loss during bed-rest. Here we present the protocol of the study and discuss its implementation. Twenty-four male subjects underwent 60-days of six-degree head down tilt bed-rest and were randomised to an inactive control group (CTR), a high-load resistive exercise group (RE) or a high-load resistive exercise with whole-body vibration group (RVE). Subsequent to events in the course of the study (e.g. subject withdrawal), 9 subjects participated in the CTR-group, 7 in the RVE-group and 8 (7 beyond bed-rest day-30) in the RE-group. Fluid intake, urine output and axiallary temperature increased during bed-rest (p or = .17). Body weight changes differed between groups (p < .0001) with decreases in the CTR-group, marginal decreases in the RE-group and the RVE-group displaying significant decreases in body-weight beyond bed-rest day-51 only. In light of events and experiences of the current study, recommendations on various aspects of bed-rest methodology are also discussed

Classes of fast and specific search mechanisms for proteins on DNA

Problems of search and recognition appear over different scales in biological systems. In this review we focus on the challenges posed by interactions between proteins, in particular transcription factors, and DNA and possible mechanisms which allow for a fast and selective target location. Initially we argue that DNA-binding proteins can be classified, broadly, into three distinct classes which we illustrate using experimental data. Each class calls for a different search process and we discuss the possible application of different search mechanisms proposed over the years to each class. The main thrust of this review is a new mechanism which is based on barrier discrimination. We introduce the model and analyze in detail its consequences. It is shown that this mechanism applies to all classes of transcription factors and can lead to a fast and specific search. Moreover, it is shown that the mechanism has interesting transient features which allow for stability at the target despite rapid binding and unbinding of the transcription factor from the target.Comment: 65 pages, 23 figure

Peanut yellow spot virus: A distinct tospovirus species based on serology and nucleic acid hybridisation

Nucleocapsids of peanut yellow spot virus (PYSV), purified from peanut (= groundnut) plant tissue, contained a protein with a molecular mass of 29 kDa. In ELISA and immuno-blot analysis the virus did not react with tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV) and peanut bud necrosis virus (PBNV) antisera. PYSV contained three RNA species, a large (L) RNA (c.8900 nucleotides), a medium (M) RNA (c.4800 nucleotides) and a small (S) RNA (c.3000 nucleotides), similar to other tospoviruses. In addition, a fourth RNA species of approximately 1800 nucleotides was also present in purified preparations. Hybridisation analysis under high stringency conditions revealed no hybridisation between PYSV RNAs and cDNA probes representing the nucleocapsid (N) gene, the glycoprotein (GP) gene and the 3' half of the RNA polymerase gene of PBNV. PYSV genomic RNAs also failed to hybridise with cDNA probes from the GP genes of TSWV and INSV. In reciprocal tests, the cDNA clones of PYSV S and M RNAs did not hybridise with any of the PBNV RNAs. Based on the absence of serological relationships between PYSV and PBNV, TSWV and INSV and lack of nucleotide homology based on hybridisation studies between the PYSV RNAs and cDNA clones from PBNV, TSWV and INSV, PYSV should be considered as a distinct species of the genus Tospovirus under a new serogroup, putatively designated ‘V

Maternal deaths in Pakistan : intersection of gender, class and social exclusion.

Background: A key aim of countries with high maternal mortality rates is to increase availability of competent maternal health care during pregnancy and childbirth. Yet, despite significant investment, countries with the highest burdens have not reduced their rates to the expected levels. We argue, taking Pakistan as a case study, that improving physical availability of services is necessary but not sufficient for reducing maternal mortality because gender inequities interact with caste and poverty to socially exclude certain groups of women from health services that are otherwise physically available. Methods: Using a critical ethnographic approach, two case studies of women who died during childbirth were pieced together from information gathered during the first six months of fieldwork in a village in Northern Punjab, Pakistan. Findings: Shida did not receive the necessary medical care because her heavily indebted family could not afford it. Zainab, a victim of domestic violence, did not receive any medical care because her martial family could not afford it, nor did they think she deserved it. Both women belonged to lower caste households, which are materially poor households and socially constructed as inferior. Conclusions: The stories of Shida and Zainab illustrate how a rigidly structured caste hierarchy, the gendered devaluing of females, and the reinforced lack of control that many impoverished women experience conspire to keep women from lifesaving health services that are physically available and should be at their disposal

Unraveling the heterogeneity of sarcoma survivors’ health-related quality of life regarding primary sarcoma location: Results from the Survsarc study

Simple SummarySarcomas are a rare group of heterogenous tumors that can develop anywhere in the body. Currently, studies on health-related quality of life (HRQoL) focus on sarcomas of the arm and leg or have too small sample sizes to examine the heterogeneity between different sarcoma locations, leading to limited insight into HRQoL of survivors with specific sarcoma locations. The aim of this study was to assess differences in HRQoL and examine treatment-specific HRQoL issues per sarcoma location. We found, in a population of 1099 sarcoma survivors, different patterns of HRQoL according to primary sarcoma location and a high number of additional, unique treatment-specific HRQoL issues per location, which were not captured with the general HRQoL questionnaire used in cancer patients. This indicates that the currently used HRQoL measures are too generic to capture all sarcoma-related issues, emphasizing the necessity for a comprehensive sarcoma-specific HRQoL measurement strategy.Sarcoma patients experience physical and psychological symptoms, depending on age of onset, subtype, treatment, stage, and location of the sarcoma, which can adversely affect patients' health-related quality of life (HRQoL). This study aimed to unravel the heterogeneity of sarcoma survivors' HRQoL regarding primary sarcoma location. A cross-sectional study was conducted among Dutch sarcoma survivors (N = 1099) aged &gt;= 18, diagnosed 2-10 years ago. Primary sarcoma locations were head and neck, chest, abdominal including retroperitoneal, pelvis including urogenital organs, axial skeleton, extremities (upper and lower), breast, skin and other locations. The European Organization for Research and Treatment of Cancer-Quality of Life Questionnaire (EORTC QLQ)-C30 was used to measure HRQoL accompanied by treatment-specific HRQoL questions. Sociodemographic and clinical characteristics were collected from the Netherlands Cancer Registry. Axial skeleton sarcomas had the lowest functioning levels and highest symptoms compared to other locations. Skin sarcomas had the highest functioning levels and lowest symptoms on most scales. Bone sarcomas scored worse on several HRQoL domains compared to soft tissue sarcomas. High prevalence of treatment-specific HRQoL issues were found per location. In conclusion, sarcomas can present everywhere, which is reflected by different HRQoL outcomes according to primary sarcoma location. The currently used HRQoL measure lacks treatment-specific questions and is too generic to capture all sarcoma-related issues, emphasizing the necessity for a comprehensive sarcoma-specific HRQoL measurement strategy.</p