284 research outputs found

    Plasmodium falciparum in Ancient Egypt

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    The deprotonation of [FeIII(N4Py)(η1-OOH)]2+ 1 gives [FeIII(N4Py)(η2-OO)]+ 2, as unequivocally demonstrated by resonance Raman spectroscopy, and leads to the loss of alkane hydroxylation activity by 1.

    A lattice model for the kinetics of rupture of fluid bilayer membranes

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    We have constructed a model for the kinetics of rupture of membranes under tension, applying physical principles relevant to lipid bilayers held together by hydrophobic interactions. The membrane is characterized by the bulk compressibility (for expansion), the thickness of the hydrophobic part of the bilayer, the hydrophobicity and a parameter characterizing the tail rigidity of the lipids. The model is a lattice model which incorporates strain relaxation, and considers the nucleation of pores at constant area, constant temperature, and constant particle number. The particle number is conserved by allowing multiple occupancy of the sites. An equilibrium ``phase diagram'' is constructed as a function of temperature and strain with the total pore surface and distribution as the order parameters. A first order rupture line is found with increasing tension, and a continuous increase in proto-pore concentration with rising temperature till instability. The model explains current results on saturated and unsaturated PC lipid bilayers and thicker artificial bilayers made of diblock copolymers. Pore size distributions are presented for various values of area expansion and temperature, and the fractal dimension of the pore edge is evaluated.Comment: 15 pages, 8 figure

    Molecular dynamic simulation of a homogeneous bcc -> hcp transition

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    We have performed molecular dynamic simulations of a Martensitic bcc->hcp transformation in a homogeneous system. The system evolves into three Martensitic variants, sharing a common nearest neighbor vector along a bcc direction, plus an fcc region. Nucleation occurs locally, followed by subsequent growth. We monitor the time-dependent scattering S(q,t) during the transformation, and find anomalous, Brillouin zone-dependent scattering similar to that observed experimentally in a number of systems above the transformation temperature. This scattering is shown to be related to the elastic strain associated with the transformation, and is not directly related to the phonon response.Comment: 11 pages plus 8 figures (GIF format); to appear in Phys. Rev.

    Mutations of the BRAF gene in human cancer

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    Cancers arise owing to the accumulation of mutations in critical genes that alter normal programmes of cell proliferation, differentiation and death. As the first stage of a systematic genome-wide screen for these genes, we have prioritized for analysis signalling pathways in which at least one gene is mutated in human cancer. The RAS RAF MEK ERK MAP kinase pathway mediates cellular responses to growth signals. RAS is mutated to an oncogenic form in about 15% of human cancer. The three RAF genes code for cytoplasmic serine/threonine kinases that are regulated by binding RAS. Here we report BRAF somatic missense mutations in 66% of malignant melanomas and at lower frequency in a wide range of human cancers. All mutations are within the kinase domain, with a single substitution (V599E) accounting for 80%. Mutated BRAF proteins have elevated kinase activity and are transforming in NIH3T3 cells. Furthermore, RAS function is not required for the growth of cancer cell lines with the V599E mutation. As BRAF is a serine/threonine kinase that is commonly activated by somatic point mutation in human cancer, it may provide new therapeutic opportunities in malignant melanoma

    Genomics studies on plantation tree species in Sarawak

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    Rapid socio-economic changes in the world are having profound impacts on all sectors, including forestry. The increase in global demand for wood requires increase in forest productivity. The alternative is to farm trees in plantations composed of fast-growing species with short rotation cycles (6–8 y). The rationale is that natural forests at the most produce about 3 m3 ha y-1 of commercial timber, whereas plantations can produce annually from 10 m3 ha y-1 of hardwoods to 30 m3 ha-1 of softwoods and thus, decrease the effects of human pressure on our ecosystems while increasing the competitiveness of Sarawak’s forest industry. This is in line with the state government’s aspiration to establish one million hectares of planted forests by year 2020 to meet the increasing demand from both domestic and international markets for raw materials. It is estimated at least 30 million seedlings are required for annual planting or reforestation programmes. In this regard, forest genomics research will help respond to the need to develop adequate tools that enable us to produce quality planting materials that are of faster growth, high yield and high wood quality, and also adapted to local conditions, so that we may achieve economic benefits of great significance. Realizing the need, we have centred our research on the development of tools via biotechnological innovations for tree breeders. Over the years, we have successfully developed: 1) simple sequence repeat (SSR) 173 DNA markers specific for identifying the genetic make-up of two fastgrowing indigenous tree species, i.e. kelampayan and sawih; 2) the ‘Touch-incubate-PCR’ approach for preparing plant tissues for high throughput genotyping, and 3) a kelampayan tree transcriptome database (NcdbEST aka CADAMOMICS) for wood formation. These tools will greatly facilitate the selection of quality planting materials for planted forest development in Sarawak as well as long-term tree improvement activities by integrating genomics into our breeding programme via association mapping. The overall benefit of genomics application to tree improvement programme will be in terms of greater certainty in the outcome of results, specifically the performance of the forest plantations, as well as the savings in time and cost in the production and supply of quality planting materials

    Large-scale magnetic fields from inflation due to a CPTCPT-even Chern-Simons-like term with Kalb-Ramond and scalar fields

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    We investigate the generation of large-scale magnetic fields due to the breaking of the conformal invariance in the electromagnetic field through the CPTCPT-even dimension-six Chern-Simons-like effective interaction with a fermion current by taking account of the dynamical Kalb-Ramond and scalar fields in inflationary cosmology. It is explicitly demonstrated that the magnetic fields on 1Mpc scale with the field strength of ∌10−9\sim 10^{-9}G at the present time can be induced.Comment: 18 pages, 6 figures, version accepted for publication in Eur. Phys. J.

    ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries

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    This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors

    7th Drug hypersensitivity meeting: part two

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