2,207 research outputs found

    Satellite Observations of Stratospheric Hydrogen Flouride and Comparisons with SLIMCAT Calculations

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    The vast majority of emissions of fluorine-containing molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Many of these fluorine-containing species deplete stratospheric ozone and are regulated by the Montreal Protocol. Once in the atmosphere they slowly degrade, ultimately leading to the formation of hydrogen fluoride (HF), the dominant reservoir of stratospheric fluorine due to its extreme stability. Monitoring the growth of stratospheric HF is therefore an important marker for the success of the Montreal Protocol. We report the comparison of global distributions and trends of HF measured in the Earth\u27s atmosphere by the satellite remote-sensing instruments ACE-FTS (Atmospheric Chemistry Experiment Fourier transform spectrometer), which has been recording atmospheric spectra since 2004, and HALOE (HALogen Occultation Experiment), which recorded atmospheric spectra between 1991 and 2005, with the output of SLIMCAT, a state-of-the-art three-dimensional chemical transport model. In general the agreement between observation and model is good, although the ACE-FTS measurements are biased high by  ∼  10 % relative to HALOE. The observed global HF trends reveal a substantial slowing down in the rate of increase of HF since the 1990s: 4.97 ± 0.12 % year−1 (1991–1997; HALOE), 1.12 ± 0.08 % year−1 (1998–2005; HALOE), and 0.52 ± 0.03 % year−1 (2004–2012; ACE-FTS). In comparison, SLIMCAT calculates trends of 4.01, 1.10, and 0.48 % year−1, respectively, for the same periods; the agreement is very good for all but the earlier of the two HALOE periods. Furthermore, the observations reveal variations in the HF trends with latitude and altitude; for example, between 2004 and 2012 HF actually decreased in the Southern Hemisphere below  ∼  35 km. An additional SLIMCAT simulation with repeating meteorology for the year 2000 produces much cleaner trends in HF with minimal variations with latitude and altitude. Therefore, the variations with latitude and altitude in the observed HF trends are due to variability in stratospheric dynamics on the timescale of a few years. Overall, the agreement between observation and model points towards the ongoing success of the Montreal Protocol and the usefulness of HF as a metric for stratospheric fluorine

    Issues of Processing and Multiple Testing of SELDI-TOF MS Proteomic Data

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    A new data filtering method for SELDI-TOF MS proteomic spectra data is described. We examined technical repeats (2 per subject) of intensity versus m/z (mass/charge) of bone marrow cell lysate for two groups of childhood leukemia patients: acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). As others have noted, the type of data processing as well as experimental variability can have a disproportionate impact on the list of interesting proteins (see Baggerly et al. (2004)). We propose a list of processing and multiple testing techniques to correct for 1) background drift; 2) filtering using smooth regression and cross-validated bandwidth selection; 3) peak finding; and 4) methods to correct for multiple testing (van der Laan et al. (2005)). The result is a list of proteins (indexed by m/z) where average expression is significantly different among disease (or treatment, etc.) groups. The procedures are intended to provide a sensible and statistically driven algorithm, which we argue provides a list of proteins that have a significant difference in expression. Given no sources of unmeasured bias (such as confounding of experimental conditions with disease status), proteins found to be statistically significant using this technique have a low probability of being false positives

    An in vitro comparison of the neurotrophic and angiogenic activity of human and canine adipose-derived mesenchymal stem cells (MSCs): translating MSC-based therapies for spinal cord injury.

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    The majority of research into the effects of mesenchymal stem cell (MSC) transplants on spinal cord injury (SCI) is performed in rodent models, which may help inform on mechanisms of action, but does not represent the scale and wound heterogeneity seen in human SCI. In contrast, SCI in dogs occurs naturally, is more akin to human SCI, and can be used to help address important aspects of the development of human MSC-based therapies. To enable translation to the clinic and a comparison across species, we have examined the paracrine, regenerative capacity of human and canine adipose-derived MSCs in vitro. MSCs were initially phenotyped according to tissue culture plastic adherence, CD immunoprofiling and tri-lineage differentiation potential. Conditioned medium (CM) from MSC cultures was then assessed for its neurotrophic and angiogenic activity using established cell-based assays. MSC CM significantly increased neuronal cell proliferation, neurite outgrowth, and βIII tubulin immunopositivity. In addition, MSC CM significantly increased endothelial cell migration, cell proliferation and the formation of tubule-like structures in Matrigel assays. There were no marked or significant differences in the capacity of human or canine MSC CM to stimulate neuronal cell or endothelial cell activity. Hence, this study supports the use of MSC transplants for canine SCI, furthermore it increases understanding of how this may subsequently provide useful information and translate to MSC transplants for human SCI

    Intussusception of the appendix secondary to endometriosis: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Intussusception of the appendix is an extremely rare condition that ranges from partial invagination of the appendix to involvement of the entire colon. Endometriosis is an exceptionally rare cause of appendiceal intussusception and only very few cases have been reported in the literature to date.</p> <p>Case presentation</p> <p>A 40 year-old woman presented to clinic with a long history of lower abdominal pain, loose motions and painful, heavy periods. Subsequent colonoscopy revealed submucosal endometriotic nodules in the sigmoid as well as a polyp thought to be arising from the appendix, which had inverted itself. She was referred to a colorectal surgeon because the polyp could not be removed endoscopically despite several attempts. At laparotomy, the appendix had intussuscepted but it was possible to reduce it and therefore a simple appendicectomy was carried out. On histology, there were widespread endometrial deposits within the wall of the appendix and this was thought to be the basis for the intussusception.</p> <p>Conclusion</p> <p>Histological evidence of the lead point is of crucial importance in cases of appendiceal intussusception, in order to exclude an underlying neoplastic process. Consequently, surgical resection is necessary either through an open or a laparoscopic approach. Gastrointestinal endometriosis should be considered as a cause of appendiceal intussusception in post-menarchal women with episodic symptoms and proven disease.</p

    A large area CsI RICH Detector in ALICE at LHC

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    A 1m2 CsI RICH prototype has been successfully tested in a hadron beam at CERN SPS. The prototype, fully equipped with 15k electronic channels, has been used to identify particles coming from pi-Be interactions. Track reconstruction has been performed by using a telescope consisting of four gas pad chambers. A detailed description of the detector will be presented and results from the test will be discussed.List of figuresFigure 1 Expected proton and antiproton yields including jet quenching mechanism in central Pb-Pb collisions at LHC.Figure 2 Schematic view of the HMPID CsI-RICHFigure 3 Experimental layout used at the SPS/H4 test beamFigure 4 Distributions of the mean number, per ring, of pad hits (Npad), electrons (Ntot) and Cherenkov photoelectrons (Nres) as a function of the single-electron mean pulse heightFigure 5 Mean single-electron pulse height as a function of high voltage measured at the centre of each of the four photocathodesFigure 6 Evaluation of the uniformity of the chamber gain for the photocathode PC32Figure 7 Azimuthal distribution of the photon pad hits in the Cherenkov fiducial zone (HV=2050 V)Figure 8 Photon angle (a) and track Cherenkov angle (b) distributions for beam events at the SPSFigure 9 Track density on the HMPID cathode plane in real 350 GeV/c pi--Be eventsFigure 10 Three dimensional display of an SPS 350 GeV/c pi--Be event. Eleven tracks are reconstructed in the telescope by requiring one hit on each pad chamber to reconstruct a track</UL

    Bone marrow lesions from osteoarthritis knees are characterized by sclerotic bone that is less well mineralized

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    INTRODUCTION. Although the presence of bone marrow lesions (BMLs) on magnetic resonance images is strongly associated with osteoarthritis progression and pain, the underlying pathology is not well established. The aim of the present study was to evaluate the architecture of subchondral bone in regions with and without BMLs from the same individual using bone histomorphometry. METHODS. Postmenopausal female subjects (n = 6, age 48 to 90 years) with predominantly medial compartment osteoarthritis and on a waiting list for total knee replacement were recruited. To identify the location of the BMLs, subjects had a magnetic resonance imaging scan performed on their study knee prior to total knee replacement using a GE 1.5 T scanner with a dedicated extremity coil. An axial map of the tibial plateau was made, delineating the precise location of the BML. After surgical removal of the tibial plateau, the BML was localized using the axial map from the magnetic resonance image and the lesion excised along with a comparably sized bone specimen adjacent to the BML and from the contralateral compartment without a BML. Cores were imaged via microcomputed tomography, and the bone volume fraction and tissue mineral density were calculated for each core. In addition, the thickness of the subchondral plate was measured, and the following quantitative metrics of trabecular structure were calculated for the subchondral trabecular bone in each core: trabecular number, thickness, and spacing, structure model index, connectivity density, and degree of anisotropy. We computed the mean and standard deviation for each parameter, and the unaffected bone from the medial tibial plateau and the bone from the lateral tibial plateau were compared with the affected BML region in the medial tibial plateau. RESULTS. Cores from the lesion area displayed increased bone volume fraction but reduced tissue mineral density. The samples from the subchondral trabecular lesion area exhibited increased trabecular thickness and were also markedly more plate-like than the bone in the other three locations, as evidenced by the lower value of the structural model index. Other differences in structure that were noted were increased trabecular spacing and a trend towards decreased trabecular number in the cores from the medial location as compared with the contralateral location. CONCLUSIONS. Our preliminary data localize specific changes in bone mineralization, remodeling and defects within BMLs features that are adjacent to the subchondral plate. These BMLs appear to be sclerotic compared with unaffected regions from the same individual based on the increased bone volume fraction and increased trabecular thickness. The mineral density in these lesions, however, is reduced and may render this area to be mechanically compromised, and thus susceptible to attrition.National Institutes of Health and National Institute of Arthritis and Musculoskeletal and Skin: Biomarkers in Osteoarthritis MRI Studies (U01 AR50900-02); AstraZenic

    Aetiology-Specific Estimates of the Global and Regional Incidence and Mortality of Diarrhoeal Diseases Commonly Transmitted through Food

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    Diarrhoeal diseases are major contributors to the global burden of disease, particularly in children. However, comprehensive estimates of the incidence and mortality due to specific aetiologies of diarrhoeal diseases are not available. The objective of this study is to provide estimates of the global and regional incidence and mortality of diarrhoeal diseases caused by nine pathogens that are commonly transmitted through foods.We abstracted data from systematic reviews and, depending on the overall mortality rates of the country, applied either a national incidence estimate approach or a modified Child Health Epidemiology Reference Group (CHERG) approach to estimate the aetiology-specific incidence and mortality of diarrhoeal diseases, by age and region. The nine diarrhoeal diseases assessed caused an estimated 1.8 billion (95% uncertainty interval [UI] 1.1-3.3 billion) cases and 599,000 (95% UI 472,000-802,000) deaths worldwide in 2010. The largest number of cases were caused by norovirus (677 million; 95% UI 468-1,153 million), enterotoxigenic Escherichia coli (ETEC) (233 million; 95% UI 154-380 million), Shigella spp. (188 million; 95% UI 94-379 million) and Giardia lamblia (179 million; 95% UI 125-263); the largest number of deaths were caused by norovirus (213,515; 95% UI 171,783-266,561), enteropathogenic E. coli (121,455; 95% UI 103,657-143,348), ETEC (73,041; 95% UI 55,474-96,984) and Shigella (64,993; 95% UI 48,966-92,357). There were marked regional differences in incidence and mortality for these nine diseases. Nearly 40% of cases and 43% of deaths caused by these nine diarrhoeal diseases occurred in children under five years of age.Diarrhoeal diseases caused by these nine pathogens are responsible for a large disease burden, particularly in children. These aetiology-specific burden estimates can inform efforts to reduce diarrhoeal diseases caused by these nine pathogens commonly transmitted through foods

    A Molybdenum(VI) Complex of 5-(2-pyridyl-1-oxide)tetrazole: synthesis, structure, and transformation into a MoO3-Based hybrid catalyst for the epoxidation of Bio-Olefins

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    The discovery of heterogeneous catalysts synthesized in easy, sustainable ways for the valorization of olefins derived from renewable biomass is attractive from environmental, sustainability, and economic viewpoints. Here, an organic–inorganic hybrid catalyst formulated as [MoO3 (Hpto)]·H2O (2), where Hpto = 5-(2-pyridyl-1-oxide)tetrazole, was prepared by a hydrolysis– condensation reaction of the complex [MoO2Cl2 (Hpto)]·THF (1). The characterization of 1 and 2 by FT-IR and Raman spectroscopies, as well as 13C solid-state NMR, suggests that the bidentate N,O-coordination of Hpto in 1 (forming a six-membered chelate ring, confirmed by X-ray crystallography) is maintained in 2, with the ligand coordinated to a molybdenum oxide substructure. Catalytic studies suggested that 2 is a rare case of a molybdenum oxide/organic hybrid that acts as a stable solid catalyst for olefin epoxidation with tert-butyl hydroperoxide. The catalyst was effective for converting biobased olefins, namely fatty acid methyl esters (methyl oleate, methyl linoleate, methyl linolenate, and methyl ricinoleate) and the terpene limonene, leading predominantly to the corresponding epoxide products with yields in the range of 85–100% after 24 h at 70 ◦C. The versatility of catalyst 2 was shown by its effectiveness for the oxidation of sulfides into sulfoxides and sulfones, at 35 ◦C (quantitative yield of sulfoxide plus sulfone, at 24 h; sulfone yields in the range of 77–86%). To the best of our knowledge, 2 is the first molybdenum catalyst reported for methyl linolenate epoxidation, and the first of the family [MoO3 (L)x] studied for methyl ricinoleate epoxidation.LA/P/0006/2020; POCI-01-0145-FEDER-030075; ALG-01-0145-FEDER-022121; grant ref. 2021.06403.BD; grant ref. 2021.04756.BD;info:eu-repo/semantics/publishedVersio
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