2,664 research outputs found

    Ultramafic xenoliths from the Bearpaw Mountains, Montana, USA: evidence for multiple metasomatic events in the lithospheric mantle beneath the Wyoming craton

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    Ultramafic xenoliths in Eocene minettes of the Bearpaw Mountains volcanic field (Montana, USA), derived from the lower lithosphere of the Wyoming craton, can be divided based on textural criteria into tectonite and cumulate groups. The tectonites consist of strongly depleted spinel lherzolites, harzburgites and dunites. Although their mineralogical compositions are generally similar to those of spinel peridotites in off-craton settings, some contain pyroxenes and spinels that have unusually low Al2O3 contents more akin to those found in cratonic spinel peridotites. Furthermore, the tectonite peridotites have whole-rock major element compositions that tend to be significantly more depleted than non-cratonic mantle spinel peridotites (high MgO, low CaO, Al2O3 and TiO2) and resemble those of cratonic mantle. These compositions could have been generated by up to 30% partial melting of an undepleted mantle source. Petrographic evidence suggests that the mantle beneath the Wyoming craton was re-enriched in three ways: (1) by silicate melts that formed mica websterite and clinopyroxenite veins; (2) by growth of phlogopite from K-rich hydrous fluids; (3) by interaction with aqueous fluids to form orthopyroxene porphyroblasts and orthopyroxenite veins. In contrast to their depleted major element compositions, the tectonite peridotites are mostly light rare earth element (LREE)-enriched and show enrichment in fluid-mobile elements such as Cs, Rb, U and Pb on mantle-normalized diagrams. Lack of enrichment in high field strength elements (HFSE; e.g. Nb, Ta, Zr and Hf) suggests that the tectonite peridotites have been metasomatized by a subduction-related fluid. Clinopyroxenes from the tectonite peridotites have distinct U-shaped REE patterns with strong LREE enrichment. They have 143Nd/144Nd values that range from 0·5121 (close to the host minette values) to 0·5107, similar to those of xenoliths from the nearby Highwood Mountains. Foliated mica websterites also have low 143Nd/144Nd values (0·5113) and extremely high 87Sr/86Sr ratios in their constituent phlogopite, indicating an ancient (probably mid-Proterozoic) enrichment. This enriched mantle lithosphere later contributed to the formation of the high-K Eocene host magmas. The cumulate group ranges from clinopyroxene-rich mica peridotites (including abundant mica wehrlites) to mica clinopyroxenites. Most contain >30% phlogopite. Their mineral compositions are similar to those of phenocrysts in the host minettes. Their whole-rock compositions are generally poorer in MgO but richer in incompatible trace elements than those of the tectonite peridotites. Whole-rock trace element patterns are enriched in large ion lithophile elements (LILE; Rb, Cs, U and Pb) and depleted in HFSE (Nb, Ta Zr and Hf) as in the host minettes, and their Sr–Nd isotopic compositions are also identical to those of the minettes. Their clinopyroxenes are LREE-enriched and formed in equilibrium with a LREE-enriched melt closely resembling the minettes. The cumulates therefore represent a much younger magmatic event, related to crystallization at mantle depths of minette magmas in Eocene times, that caused further metasomatic enrichment of the lithosphere

    Hydrodynamic stability and mode coupling in Keplerian flows: local strato-rotational analysis

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    Aims. Qualitative analysis of key (but yet unappreciated) linear phenomena in stratified hydrodynamic Keplerian flows: (i) the occurrence of a vortex mode, as a consequence of strato-rotational balance, with its transient dynamics; (ii) the generation of spiral-density waves (also called inertia-gravity or gΩg\Omega waves) by the vortex mode through linear mode coupling in shear flows. Methods. Non-modal analysis of linearized Boussinesq equations written in the shearing sheet approximation of accretion disk flows. Results. It is shown that the combined action of rotation and stratification introduces a new degree of freedom -- vortex mode perturbation -- which is linearly coupled with the spiral-density waves. These two modes are jointly able to extract energy from the background flow and they govern the disk dynamics in the small-scale range. The transient behavior of these modes is determined by the non-normality of the Keplerian shear flow. Tightly leading vortex mode perturbations undergo substantial transient growth, then, becoming trailing, inevitably generate trailing spiral-density waves by linear mode coupling. This course of events -- transient growth plus coupling -- is particularly pronounced for perturbation harmonics with comparable azimuthal and vertical scales and it renders the energy dynamics similar to the 3D unbounded plane Couette flow case. Conclusions. Our investigation strongly suggests that the so-called bypass concept of turbulence, which has been recently developed by the hydrodynamic community for spectrally stable shear flows, can also be applied to Keplerian disks. This conjecture may be confirmed by appropriate numerical simulations that take in account the vertical stratification and consequent mode coupling in the high Reynolds number regime.Comment: A&A (accepted

    Sequence variation of Epstein-Barr virus: viral types, geography, codon usage and diseases

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    138 new Epstein-Barr virus (EBV) genome sequences have been determined. 125 of these and 116 from previous reports were combined to produce a multiple sequence alignment of 241 EBV genomes, which we have used to analyze variation within the viral genome. The type 1/type2 classification of EBV remains the major form of variation and is defined mostly by EBNA2 and EBNA3, but the type 2 SNPs at the EBNA3 locus extend into the adjacent gp350 and gp42 genes, whose products mediate infection of B cells by EBV. A small insertion within the BART miRNA region of the genome was present in 21 EBV strains. EBV from saliva of USA patients with chronic active EBV infection aligned with the wild type EBV genome, with no evidence of WZhet rearrangements. The V3 polymorphism in the Zp promoter for BZLF1 was found to be frequent in nasopharyngeal carcinoma cases both from Hong Kong and Indonesia. Codon usage was found to differ between latent and lytic cycle EBV genes and the main forms of variation of the EBNA1 protein have been identified.IMPORTANCE Epstein-Barr virus causes most cases of infectious mononucleosis and post-transplant lymphoproliferative disease. It contributes to several types of cancer including Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B cell lymphoma, nasopharyngeal carcinoma and gastric carcinoma. EBV genome variation is important because some of the diseases associated with EBV have very different incidences in different populations and geographic regions - differences in the EBV genome might contribute to these diseases. Some specific EBV genome alterations that appear to be significant in EBV associated cancers are already known and current efforts to make an EBV vaccine and antiviral drugs should also take account of sequence differences in the proteins used as targets

    Regional outbreak of staphylococcal scalded skin syndrome in healthy children

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    Purpose : Staphylococcal scalded skin syndrome (SSSS) is a relatively uncommon superficial blistering skin disease that is due to Staphylococcus aureus. We had experienced a regional outbreak of SSSS over 3 years in healthy children. Methods : We retrospectively reviewed the medical records of those patients diagnosed as SSSS. Most of neonatal cases were nosocomial infections and excluded from the analysis. The clinical features, laboratory findings, the isolation and antibiotic resistance of S. aureus, the antibiotic management and other supportive treatments were analyzed. Results : Fifty-five patients with SSSS were admitted to our hospital from October 2001 to September 2004. The median age of patients was 3.0 years. Of the 55 patients, 9 were the generalized type, 13 were the intermediate type and 33 were the scarletiniform rash. All the patients were living in neighborhood of the Jinju area. S. aureus were isolated from 9 of the patients and all of the isolated S. aureus were methicillin resistant. All the patients except two were treated with intravenous flocloxacillin or nafcillin and/or cefotaxime. All the patients recovered during the follow-up period of 2 to 3 weeks. Conclusion : We experienced a regional outbreak of SSSS in previous healthy children. Further study for finding the carriers of S. aureus caused SSSS and preventing the spread of this disease is needed. Additionally, guidelines for treating SSSS due to methicillin resistant S. aureus should be established

    Treating implicit trauma: a quasi-experimental study comparing the EMDR Therapy Standard Protocol with a ‘Blind 2 Therapist’ version within a trauma capacity building project in Northern Iraq

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    Psychological trauma is a silent epidemic which presents as a global public health issue, often in the form of post- traumatic stress disorder (PTSD). Eye Movement Desensitisation and Reprocessing (EMDR) Therapy is an empirically supported treatment intervention for PTSD and has been used as part of trauma-capacity building, particularly in low- and middle-income countries (LMIC). For some survivor’s, their trauma experiences cannot be spoken of: they may be alluded to, suggested and though not directly expressed. There are several factors as to why these implicit trauma experiences are ‘unspoken’, for example, when the trauma involves a deep-rooted sense of shame or guilt, a distorted sense of over-responsibility or when to speak of the trauma engenders fear of retribution, reprisal and consequence. This paper will explore the effectiveness of using two protocol variations of EMDR Therapy—standard versus a ‘Blind 2 Therapist’ protocol version as part of a quasi-experimental study which took place in Northern Iraq. The study contains two projects and subsequently tested several hypotheses regarding safety, effectiveness, efficiency and relevance of the ‘Blind 2 Therapist’ protocol within EMDR Therapy. Results indicated support for the B2T protocol intervention with various trauma populations including Yezidi survivors of Islamic State of Iraq and the Levant (ISIL)—also known as Daesh

    Influence of cyclin type and dose on mitotic entry and progression in the early Drosophila embryo

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    Cyclins are key cell cycle regulators, yet few analyses test their role in timing the events that they regulate. We used RNA interference and real-time visualization in embryos to define the events regulated by each of the three mitotic cyclins of Drosophila melanogaster, CycA, CycB, and CycB3. Each individual and pairwise knockdown results in distinct mitotic phenotypes. For example, mitosis without metaphase occurs upon knockdown of CycA and CycB. To separate the role of cyclin levels from the influences of cyclin type, we knocked down two cyclins and reduced the gene dose of the one remaining cyclin. This reduction did not prolong interphase but instead interrupted mitotic progression. Mitotic prophase chromosomes formed, centrosomes divided, and nuclei exited mitosis without executing later events. This prompt but curtailed mitosis shows that accumulation of cyclin function does not directly time mitotic entry in these early embryonic cycles and that cyclin function can be sufficient for some mitotic events although inadequate for others

    Cystic Fibrosis in Korean Children: A Case Report Identified by a Quantitative Pilocarpine Iontophoresis Sweat Test and Genetic Analysis

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    Cystic fibrosis (CF) is inherited as an autosomal recessive trait, and the mutations in cystic fibrosis transmembrane conductance regulator (CFTR) gene contributes to the CF syndrome. Although CF is common in Caucasians, it is known to be rare in Asians. Recently, we experienced two cases of CF in Korean children. The patients were girls with chronic productive cough since early infancy. Chest computed tomography showed the diffuse bronchiectasis in both lungs, and their diagnosis was confirmed by the repeated analysis of a quantitative pilocarpine iontophoresis test (QPIT). The sweat chloride concentrations of the first patient were 108.1 mM/L and 96.7 mM/L. The genetic analysis revealed that she was the compound heterozygote of Q1291X and IVS8 T5-M470V. In the second case, the sweat chloride concentrations were 95.0 mM/L and 77.5 mM/L. Although we performed a comprehensive search for the coding regions and exon-intron splicing junctions of CFTR gene, no obvious disease-related mutations were detected in the second case. To our knowledge, this is the first report of CF in Korean children identified by a QPIT and genetic analysis. The possibility of CF should be suspected in those patients with chronic respiratory symptoms even in Korea

    Spatio-temporal Models of Lymphangiogenesis in Wound Healing

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    Several studies suggest that one possible cause of impaired wound healing is failed or insufficient lymphangiogenesis, that is the formation of new lymphatic capillaries. Although many mathematical models have been developed to describe the formation of blood capillaries (angiogenesis), very few have been proposed for the regeneration of the lymphatic network. Lymphangiogenesis is a markedly different process from angiogenesis, occurring at different times and in response to different chemical stimuli. Two main hypotheses have been proposed: 1) lymphatic capillaries sprout from existing interrupted ones at the edge of the wound in analogy to the blood angiogenesis case; 2) lymphatic endothelial cells first pool in the wound region following the lymph flow and then, once sufficiently populated, start to form a network. Here we present two PDE models describing lymphangiogenesis according to these two different hypotheses. Further, we include the effect of advection due to interstitial flow and lymph flow coming from open capillaries. The variables represent different cell densities and growth factor concentrations, and where possible the parameters are estimated from biological data. The models are then solved numerically and the results are compared with the available biological literature.Comment: 29 pages, 9 Figures, 6 Tables (39 figure files in total

    Continental mass change from GRACE over 2002-2011 and its impact on sea level

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    Present-day continental mass variation as observed by space gravimetry reveals secular mass decline and accumulation. Whereas the former contributes to sea-level rise, the latter results in sea-level fall. As such, consideration of mass accumulation (rather than focussing solely on mass loss) is important for reliable overall estimates of sea-level change. Using data from the Gravity Recovery And Climate Experiment satellite mission, we quantify mass-change trends in 19 continental areas that exhibit a dominant signal. The integrated mass change within these regions is representative of the variation over the whole land areas. During the integer 9-year period of May 2002 to April 2011, GIA-adjusted mass gain and mass loss in these areas contributed, on average, to −(0.7 ± 0.4) mm/year of sea-level fall and + (1.8 ± 0.2) mm/year of sea-level rise; the net effect was + (1.1 ± 0.6) mm/year. Ice melting over Greenland, Iceland, Svalbard, the Canadian Arctic archipelago, Antarctica, Alaska and Patagonia was responsible for + (1.4±0.2) mm/year of the total balance. Hence, land-water mass accumulation compensated about 20 % of the impact of ice-melt water influx to the oceans. In order to assess the impact of geocentre motion, we converted geocentre coordinates derived from satellite laser ranging (SLR) to degree-one geopotential coefficients. We found geocentre motion to introduce small biases to mass-change and sea-level change estimates; its overall effect is + (0.1 ± 0.1) mm/year. This value, however, should be taken with care owing to questionable reliability of secular trends in SLR-derived geocentre coordinates
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