326 research outputs found

    A Geometrical Test of the Cosmological Energy Contents Using the Lyman-alpha Forest

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    In this Letter we explore a version of the test of cosmological geometry proposed by Alcock and Paczynski (1979), using observations of the Lyman-alpha forest in the spectra of close quasar pairs. By comparing the correlations in absorption in one quasar spectrum with correlations between the spectra of neighboring quasars one can determine the relation of the redshift distance scale to the angle distance scale at the redshift of the absorbers, z24z \sim 2 - 4. Since this relationship depends on the parameters of the cosmological model, these parameters may be determined using the Lyman-alpha forest. While this test is relatively insensitive to the density parameter Ωm\Omega_m in a dust-dominated universe, it is more sensitive to the presence of a matter component with large negative pressure (such as a cosmological constant Λ\Lambda) and its equation of state. With only 25 pairs of quasar spectra at angular separations 0.520.5' - 2', one can discriminate between an Ωm=0.3\Omega_m = 0.3 open universe (Λ=0\Lambda=0) and an Ωm=0.3\Omega_m = 0.3 flat (Λ\Lambda-dominated) universe at the 4σ4-\sigma level. The S/N can be enhanced by considering quasar pairs at smaller angular separations, but requires proper modeling of nonlinear redshift space distortions. Here the correlations and redshift space distortions are modeled using linear theory.Comment: 13 pages, 2 ps figures, submitted to ApJ

    Indications of a positive feedback between coastal development and beach nourishment

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    Beach nourishment, a method for mitigating coastal storm damage or chronic erosion by deliberately replacing sand on an eroded beach, has been the leading form of coastal protection in the United States for four decades. However, investment in hazard protection can have the unintended consequence of encouraging development in places especially vulnerable to damage. In a comprehensive, parcel-scale analysis of all shorefront single-family homes in the state of Florida, we find that houses in nourishing zones are significantly larger and more numerous than in non-nourishing zones. The predominance of larger homes in nourishing zones suggests a positive feedback between nourishment and development that is compounding coastal risk in zones already characterized by high vulnerability

    Mitochondrial DNA mutations in human degenerative diseases and aging

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    AbstractA wide variety of mitochondrial DNA (mtDNA) mutations have recently been identified in degenerative diseases of the brain, heart, skeletal muscle, kidney and endocrine system. Generally, individuals inheriting these mitochondrial diseases are relatively normal in early life, develop symptoms during childhood, mid-life, or old age depending on the severity of the maternally-inherited mtDNA mutation; and then undergo a progressive decline. These novel features of mtDNA disease are proposed to be the product of the high dependence of the target organs on mitochondrial bioenergetics, and the cumulative oxidative phosphorylation (OXPHOS) defect caused by the inherited mtDNA mutation together with the age-related accumulation mtDNA mutations in post-mitotic tissues

    Perinatal Tobacco Smoke Exposure Increases Vascular Oxidative Stress and Mitochondrial Damage in Non-Human Primates

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    Epidemiological studies suggest that events occurring during fetal and early childhood development influence disease susceptibility. Similarly, molecular studies in mice have shown that in utero exposure to cardiovascular disease (CVD) risk factors such as environmental tobacco smoke (ETS) increased adult atherogenic susceptibility and mitochondrial damage; however, the molecular effects of similar exposures in primates are not yet known. To determine whether perinatal ETS exposure increased mitochondrial damage, dysfunction and oxidant stress in primates, archived tissues from the non-human primate model Macaca mulatta (M. mulatta) were utilized. M. mulatta were exposed to low levels of ETS (1 mg/m3 total suspended particulates) from gestation (day 40) to early childhood (1 year), and aortic tissues were assessed for oxidized proteins (protein carbonyls), antioxidant activity (SOD), mitochondrial function (cytochrome oxidase), and mitochondrial damage (mitochondrial DNA damage). Results revealed that perinatal ETS exposure resulted in significantly increased oxidative stress, mitochondrial dysfunction and damage which were accompanied by significantly decreased mitochondrial antioxidant capacity and mitochondrial copy number in vascular tissue. Increased mitochondrial damage was also detected in buffy coat tissues in exposed M. mulatta. These studies suggest that perinatal tobacco smoke exposure increases vascular oxidative stress and mitochondrial damage in primates, potentially increasing adult disease susceptibility

    Indications of a positive feedback between coastal development and beach nourishment: COASTAL DEVELOPMENT BEACH NOURISHMENT

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    Beach nourishment, a method for mitigating coastal storm damage or chronic erosion by deliberately replacing sand on an eroded beach, has been the leading form of coastal protection in the United States for four decades. However, investment in hazard protection can have the unintended consequence of encouraging development in places especially vulnerable to damage. In a comprehensive, parcel‐scale analysis of all shorefront single‐family homes in the state of Florida, we find that houses in nourishing zones are significantly larger and more numerous than in non‐nourishing zones. The predominance of larger homes in nourishing zones suggests a positive feedback between nourishment and development that is compounding coastal risk in zones already characterized by high vulnerability

    2022 taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales

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    In March 2022, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by two new families (bunyaviral Discoviridae and Tulasviridae), 41 new genera, and 98 new species. Three hundred forty-nine species were renamed and/or moved. The accidentally misspelled names of seven species were corrected. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.Instituto de Patología VegetalFil: Kuhn, Jens H. National Institute of Allergy and Infectious Diseases. National Institutes of Health. Integrated Research Facility at Fort Detrick; Estados UnidosFil: Adkins, Scott. US Horticultural Research Laboratory. United States Department of Agriculture. Agricultural Research Service; Estados UnidosFil: Alkhovsky, Sergey V. Ministry of Health of Russian Federation. National Center on Epidemiology and Microbiology .D.I. Ivanovsky Institute of Virology of N.F. Gamaleya; RusiaFil: Avšič-Županc, Tatjana. University of Ljubljana. Faculty of Medicine. Institute of Microbiology and Immunology; EsloveniaFil: Ayllón, María A. Universidad Politécnica de Madrid. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria.Centro de Biotecnología y Genómica de Plantas; EspañaFil: Ayllón, María A. Universidad Politécnica de Madrid. Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas. Departamento de Biotecnología-Biología Vegetal; EspañaFil: Bahl, Justin. University of Georgia. Center for Ecology of Infectious Diseases. Insitute of Bioinformatics. Department of Infectious Diseases. Department of Epidemiology and Biostatistics; Estados UnidosFil: Balkema-Buschmann, Anne. Friedrich-Loeffler-Institut. Institute of Novel and Emerging Infectious Diseases; AlemaniaFil: Ballinger, Matthew J. Mississippi State University. Department of Biological Sciences; Estados UnidosFil: Bandte, Martina. Humboldt-Universität zu Berlin. Faculty of Life Sciences. Division Phytomedicine; AlemaniaFil: Beer, Martin. Friedrich-Loeffler-Institut. Institute of Diagnostic Virology; AlemaniaFil: Bejerman, Nicolas Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Bejerman, Nicolas Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Fitopatología y Modelización Agrícola (UFyMA); ArgentinaFil: Lodden Økland, Arnfnn. Pharmaq Analytiq; Norueg

    Single-scatter Monte Carlo compared to condensed history results for low energy electrons

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    A Monte Carlo code has been developed to simulate individual electron interactions. The code has been instrumental in determining the range of validity for the widely used condensed history method. This task was accomplished by isolating and testing the condensed history assumptions. The results show that the condensed history method fails for low energy electron transport due to inaccuracies in energy loss and spatial positioning.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29795/1/0000141.pd

    A simplified high-throughput method for pyrethroid knock-down resistance (kdr) detection in Anopheles gambiae

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    BACKGROUND: A single base pair mutation in the sodium channel confers knock-down resistance to pyrethroids in many insect species. Its occurrence in Anopheles mosquitoes may have important implications for malaria vector control especially considering the current trend for large scale pyrethroid-treated bednet programmes. Screening Anopheles gambiae populations for the kdr mutation has become one of the mainstays of programmes that monitor the development of insecticide resistance. The screening is commonly performed using a multiplex Polymerase Chain Reaction (PCR) which, since it is reliant on a single nucleotide polymorphism, can be unreliable. Here we present a reliable and potentially high throughput method for screening An. gambiae for the kdr mutation. METHODS: A Hot Ligation Oligonucleotide Assay (HOLA) was developed to detect both the East and West African kdr alleles in the homozygous and heterozygous states, and was optimized for use in low-tech developing world laboratories. Results from the HOLA were compared to results from the multiplex PCR for field and laboratory mosquito specimens to provide verification of the robustness and sensitivity of the technique. RESULTS AND DISCUSSION: The HOLA assay, developed for detection of the kdr mutation, gives a bright blue colouration for a positive result whilst negative reactions remain colourless. The results are apparent within a few minutes of adding the final substrate and can be scored by eye. Heterozygotes are scored when a sample gives a positive reaction to the susceptible probe and the kdr probe. The technique uses only basic laboratory equipment and skills and can be carried out by anyone familiar with the Enzyme-linked immunosorbent assay (ELISA) technique. A comparison to the multiplex PCR method showed that the HOLA assay was more reliable, and scoring of the plates was less ambiguous. CONCLUSION: The method is capable of detecting both the East and West African kdr alleles in the homozygous and heterozygous states from fresh or dried material using several DNA extraction methods. It is more reliable than the traditional PCR method and may be more sensitive for the detection of heterozygotes. It is inexpensive, simple and relatively safe making it suitable for use in resource-poor countries
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