587 research outputs found

    The reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards difunctional chloroacetamide alkylating agents: Formation of cyclized or bridged products

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    The reactions of [Pt₂(μ-S)₂(PPh₃)₄] towards some bis(chloroacetamide) alkylating agents have been investigated. Reaction with one mole equivalent of the hydrazine-derived compound ClCH₂C(O)NHNHC(O)CH₂Cl led to the cyclized product [Pt₂{SCH₂C(O)NHNHC(O)CH₂S}(PPh₃)₄]²⁺ which showed two different PPh₃ environments in the ³¹P{1H} NMR spectrum, as a result of non-fluxional behavior of the dithiolate ligand in solution. Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with the ortho and para isomers of the phenylenediamine-derived bis(chloroacetamides) ClCH2C(O)NHC6H4NHC(O)CH2Cl gave tetrametallic complexes containing two {Pt₂S₂} moieties spanned by the CH₂C(O)NHC₆H₄NHC(O)CH₂ group. Both the ortho and para isomers were crystallographically characterized; in the ortho isomer there is intramolecular CO=H–N and S•••H–N hydrogen bonding involving the two amide groups

    Vector competence of Aedes aegypti, Culex tarsalis, and Culex quinquefasciatus from California for Zika virus.

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    Zika virus (ZIKV) has emerged since 2013 as a significant global human health threat following outbreaks in the Pacific Islands and rapid spread throughout South and Central America. Severe congenital and neurological sequelae have been linked to ZIKV infections. Assessing the ability of common mosquito species to transmit ZIKV and characterizing variation in mosquito transmission of different ZIKV strains is important for estimating regional outbreak potential and for prioritizing local mosquito control strategies for Aedes and Culex species. In this study, we evaluated the laboratory vector competence of Aedes aegypti, Culex quinquefasciatus, and Culex tarsalis that originated in areas of California where ZIKV cases in travelers since 2015 were frequent. We compared infection, dissemination, and transmission rates by measuring ZIKV RNA levels in cohorts of mosquitoes that ingested blood meals from type I interferon-deficient mice infected with either a Puerto Rican ZIKV strain from 2015 (PR15), a Brazilian ZIKV strain from 2015 (BR15), or an ancestral Asian-lineage Malaysian ZIKV strain from 1966 (MA66). With PR15, Cx. quinquefasciatus was refractory to infection (0%, N = 42) and Cx. tarsalis was infected at 4% (N = 46). No ZIKV RNA was detected in saliva from either Culex species 14 or 21 days post feeding (dpf). In contrast, Ae. aegypti developed infection rates of 85% (PR15; N = 46), 90% (BR15; N = 20), and 81% (MA66; N = 85) 14 or 15 dpf. Although MA66-infected Ae. aegypti showed higher levels of ZIKV RNA in mosquito bodies and legs, transmission rates were not significantly different across virus strains (P = 0.13, Fisher's exact test). To confirm infectivity and measure the transmitted ZIKV dose, we enumerated infectious ZIKV in Ae. aegypti saliva using Vero cell plaque assays. The expectorated plaque forming units PFU varied by viral strain: MA66-infected expectorated 13±4 PFU (mean±SE, N = 13) compared to 29±6 PFU for PR15-infected (N = 13) and 35±8 PFU for BR15-infected (N = 6; ANOVA, df = 2, F = 3.8, P = 0.035). These laboratory vector competence results support an emerging consensus that Cx. tarsalis and Cx. quinquefasciatus are not vectors of ZIKV. These results also indicate that Ae. aegypti from California are efficient laboratory vectors of ancestral and contemporary Asian lineage ZIKV

    THE ROLES AND MECHANISMS OF LINEAR AND ANGULAR IMPULSE GENERATION FOR BOTH LEGS IN BASEBALL PITCHING: A WHOLE-BODY PERSPECTIVE

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    This study compared the role of each leg in generating linear and angular impulse during fastball pitches performed by professional pitchers (n=4). Participants were asked to pitch from an instrumented mound and 6-11 successful fastball pitches were used for the analysis. The results indicate that back leg generated forward linear impulse and the front leg generated backward linear impulse for all pitchers. Back leg ground reaction forces generated significantly larger angular impulse about a horizontal axis passing through the body center of mass from the mound to first base than the front leg in three of four pitchers. Additionally, the mechanisms of moment generation about the axis by each leg differed

    The 1990 update to strategy for exploration of the inner planets

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    The Committee on Planetary and Lunar Exploration (COMPLEX) has undertaken to review and revise the 1978 report Strategy for Exploration of the Inner Planets, 1977-1987. The committee has found the 1978 report to be generally still pertinent. COMPLEX therefore issues its new report in the form of an update. The committee reaffirms the basic objectives for exploration of the planets: to determine the present state of the planets and their satellites, to understand the processes active now and at the origin of the solar system, and to understand planetary evolution, including appearance of life and its relation to the chemical history of the solar system

    A 3D APPROACH TO BASEBALL PITCHING KINEMATIC SEQUENCE

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    A proximal-to-distal sequence (PDS) in baseball pitching is theorized to be more efficient and can reduce upper limb joint loads. However, studies investigating PDS using timing of peak segment angular velocity magnitude did not identify the use of “full” PDS from pelvis to hand. This study investigated PDS by comparing the timings of peak angular velocities about each global axis for the pelvis, trunk, upper arm, forearm, and hand during fastballs thrown by professional pitchers (n=4). We found that pitchers demonstrated full PDS about the global left axis (from pitching mound to first base) in 67-100% of their trials, depending on the pitcher. No pitcher demonstrated full PDS about the other two global axes. Similar to prior studies, we also did not observe full PDS when using angular velocity magnitude. This could be explained by differences in body segment rotation sequences between global axes. We also preliminarily uncovered impacts of filtering on the kinematic sequence detected. Analyzing 3D angular velocities with carefully selected filters may advance our understanding of the dynamics of pitching

    Outcome of Diagnostic Tests Using Samples from Patients with Culture-Proven Human Monocytic Ehrlichiosis: Implications for Surveillance

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    We describe the concordance among results from various laboratory tests using samples derived from nine culture-proven cases of human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis. A class-specific indirect immunofluorescence assay for immunoglobulin M (IgM) and IgG, using E. chaffeensis antigen, identified 44 and 33% of the isolation-confirmed HME patients on the basis of samples obtained at initial clinical presentation, respectively; detection of morulae in blood smears was similarly insensitive (22% positive). PCR amplifications of ehrlichial DNA targeting the 16S rRNA gene, the variable-length PCR target gene, and the groESL operon were positive for whole blood specimens obtained from all patients at initial presentation. As most case definitions of HME require a serologic response with compatible illness for a categorization of even probable disease, PCR would have been required to confirm the diagnosis of HME in all nine of these patients without the submission of a convalescent-phase serum sample. These data suggest that many, if not most, cases of HME in patients who present early in the course of the disease may be missed and underscore the limitations of serologically based surveillance systems

    Beyond the molecular movie: Dynamics of bands and bonds during a photoinduced phase transition

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    Ultrafast nonequilibrium dynamics offer a route to study the microscopic interactions that govern macroscopic behavior. In particular, photoinduced phase transitions (PIPTs) in solids provide a test case for how forces, and the resulting atomic motion along a reaction coordinate, originate from a nonequilibrium population of excited electronic states. Using femtosecond photoemission, we obtain access to the transient electronic structure during an ultrafast PIPT in a model system: indium nanowires on a silicon(111) surface. We uncover a detailed reaction pathway, allowing a direct comparison with the dynamics predicted by ab initio simulations. This further reveals the crucial role played by localized photoholes in shaping the potential energy landscape and enables a combined momentum- and real-space description of PIPTs, including the ultrafast formation of chemical bonds

    Mobius domain-wall fermions on gradient-flowed dynamical HISQ ensembles

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    We report on salient features of a mixed lattice QCD action using valence Mobius domain-wall fermions solved on the dynamical N-f = 2 + 1 + 1 highly improved staggered quark sea- quark ensembles generated by the MILC Collaboration. The approximate chiral symmetry properties of the valence fermions are shown to be significantly improved by utilizing the gradient- flow scheme to first smear the highly improved staggered quark configurations. The greater numerical cost of the Mobius domain- wall inversions is mitigated by the highly efficient QUDA library optimized for NVIDIA GPU accelerated compute nodes. We have created an interface to this optimized QUDA solver in CHROMA. We provide tuned parameters of the action and performance of QUDA using ensembles with the lattice spacings a similar or equal to {0.15; 0.12; 0.09} fm and pion masses m(pi) similar or equal to {310; 220; 130} MeV. We have additionally generated two new ensembles with a similar to 0.12 fm and m(pi) similar to {400; 350} MeV. With a fixed flow time of t(gf) = 1 in lattice units, the residual chiral symmetry breaking of the valence fermions is kept below 10% of the light quark mass on all ensembles, m(res) less than or similar to 0.1 x m(l), with moderate values of the fifth dimension L-5 and a domain- wall height M-5 \u3c= 1.3. As a benchmark calculation, we perform a continuum, infinite volume, physical pion and kaon mass extrapolation of F-K +/-/F-pi +/- and demonstrate our results are independent of flow time and consistent with the FLAG determination of this quantity at the level of less than one standard deviation
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