13,598 research outputs found

    Charge transfer complexes and radical cation salts of chiral methylated organosulfur donors

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    The single crystal X-ray structure of the all-axial conformer of the (R,R,R,R) enantiomer of the chiral donor tetramethyl-BEDT-TTF (TM-BEDT-TTF) was described and compared to the all-equatorial conformer. (S,S,S,S)-Tetramethyl-BEDT-TTF formed crystalline 1 : 1 complexes with TCNQ and TCNQ-F4, as well as a THF solvate of the TCNQ complex. Donors bis((2S,4S)-pentane-2,4-dithio)tetrathiafulvalene and (ethylenedithio)((2S,4S)-pentane-2,4-dithio)tetrathiafulvalene, which contain seven-membered rings bearing chirally oriented methyl groups, only formed complexes with TCNQ-F4. The TCNQ-F4 complexes contain planar organosulfur systems, in contrast to the TCNQ complexes in which there is minimal charge transfer. A variety of crystal packing modes were observed. Electrocrystallization experiments with both enantiomers and the racemic form of tetramethyl-BEDT-TTF afforded mixed valence radical cation salts with the AsF6 and SbF6 anions formulated as (TM-BEDT-TTF)2XF6 (X = As, Sb). Electrical conductivity was only found in one charge transfer complex, while the radical cation salts are all semiconducting

    Anticipation and Adaptation in Particulate Matter Policy: The European Union, the Netherlands, and United States

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    The evolution of particulate matter (PM) air quality policy in the European Union and in the United States between 1970 and the present has been atypical. The US government and the European Commission have mandated scheduled reviews of PM policy over the past three decades and have updated that policy to new scientific information on multiple occasions. The use of planned adaptation over such a long period and in this manner, as a means to deal with uncertainty, has not often been reproduced in air quality policy. Furthermore, particulate matter policy in the EU and US does not conform to the commonly held perception that the EU’s environmental policies are, by and large, more precautionary than the respective policies in the United States. The US decisions to adopt air quality standards for PM10 and PM2.5, in 1987 and 1997 respectively, led those in the EU by approximately nine years. An analysis of the comparative stringency of the PM standards in the US and EU shows that the PM2.5 standard the US implemented in 1997 is more stringent than the standards that have been proposed in the EU by the European Commission and the European Parliament. In September this year, the US repealed their annual standard for PM10. Prior to that, however, the annual PM10 standard the EU implemented in 1999 was more stringent than the one the US adopted in 1987. The daily PM10 standards in the EU and US are of similar stringency. In the Appendix, these comparisons in stringency are discussed in more detail. The differences between the EU and US policies are remarkable because they are based on the same science and therefore reflect dissimilar processes of interpreting that science and the uncertainties inherent in it. The two cases themselves focus on the sciencepolicy interfaces for their respective governing bodies. The EU case also looks at the science-policy interface in the Netherlands. The US case also examines policies for sulfur dioxides that relate to the PM policies. The remainder of this summary discusses how characteristics of the science-policy interfaces may have led to the differences in outcomes

    Synthesis of new chiral organosulfur donors with hydrogen bonding functionality and their first charge transfer salts

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    The syntheses of a range of enantiopure organosulfur donors with hydrogen bonding groups are described including TTF related materials with two, four, six and eight hydroxyl groups and multiple stereogenic centres and a pair of chiral N-substituted BEDT-TTF acetamides. Three charge transfer salts of enantiopure poly-hydroxy-substituted donors are reported, including a 4:1 salt with the meso stereoisomer of the dinuclear [Fe2(oxalate)5 ]4- anion in which both cation and anion have chiral components linked together by hydrogen bonding, and a semiconducting salt with triiodide

    The effect of exogenous corticosterone on West Nile virus infection in Northern Cardinals (Cardinalis cardinalis)

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    The relationship between stress and disease is thought to be unambiguous: chronic stress induces immunosuppression, which likely increases the risk of infection. However, this link has not been firmly established in wild animals, particularly whether stress hormones affect host responses to zoonotic pathogens, which can be transmitted to domesticated animal, wildlife and human populations. Due to the dynamic effects of stress hormones on immune functions, stress hormones may make hosts better or poorer amplifying hosts for a pathogen contingent on context and the host species evaluated. Using an important zoonotic pathogen, West Nile virus (WNV) and a competent host, the Northern Cardinal (Cardinalis cardinalis), we tested the effects of exogenous corticosterone on response to WNV infection. Corticosterone was administered at levels that individuals enduring chronic stressors (i.e., long-term inclement weather, food shortage, anthropogenic pollution) might experience in the wild. Corticosterone greatly impacted mortality: half of the corticosterone-implanted cardinals died between five - 11 days post-inoculation whereas only one of nine empty-implanted (control) birds died. No differences were found in viral titer between corticosterone- and empty-implanted birds. However, cardinals that survived infections had significantly higher average body temperatures during peak infection than individuals that died. In sum, this study indicates that elevated corticosterone could affect the survival of WNV-infected wild birds, suggesting that populations may be disproportionately at-risk to disease in stressful environments

    The structural effects of mutations can aid in differential phenotype prediction of beta-myosin heavy chain (Myosin-7) missense variants

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    MOTIVATION: High-throughput sequencing platforms are increasingly used to screen patients with genetic disease for pathogenic mutations, but prediction of the effects of mutations remains challenging. Previously we developed SAAPdap (Single Amino Acid Polymorphism Data Analysis Pipeline) and SAAPpred (Single Amino Acid Polymorphism Predictor) that use a combination of rule-based structural measures to predict whether a missense genetic variant is pathogenic. Here we investigate whether the same methodology can be used to develop a differential phenotype predictor, which, once a mutation has been predicted as pathogenic, is able to distinguish between phenotypes-in this case the two major clinical phenotypes (hypertrophic cardiomyopathy, HCM, and dilated cardiomyopathy, DCM) associated with mutations in the beta-myosin heavy chain (MYH7) gene product (Myosin-7). RESULTS: A random forest predictor trained on rule-based structural analyses together with structural clustering data gave a Matthews' correlation coefficient (MCC) of 0.53 (accuracy, 75%). A post hoc removal of machine learning models that performed particularly badly, increased the performance (MCC = 0.61, Acc = 79%). This proof of concept suggests that methods used for pathogenicity prediction can be extended for use in differential phenotype prediction

    Revealing the velocity structure of the filamentary nebula in NGC 1275 in its entirety

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    We have produced for the first time a detailed velocity map of the giant filamentary nebula surrounding NGC 1275, the Perseus cluster’s brightest galaxy, and revealed a previously unknown rich velocity structure across the entire nebula. These new observations were obtained with the optical imaging Fourier transform spectrometer SITELLE at CFHT. With its wide field of view ( ∼11 arcmin × 11 arcmin), SITELLE is the only integral field unit spectroscopy instrument able to cover the 80 kpc  ×  55 kpc ( 3.8 arcmin × 2.6 arcmin) large nebula in NGC 1275. Our analysis of these observations shows a smooth radial gradient of the [N II]λ6583/H α line ratio, suggesting a change in the ionization mechanism and source across the nebula. The velocity map shows no visible general trend or rotation, indicating that filaments are not falling uniformly onto the galaxy, nor being uniformly pulled out from it. Comparison between the physical properties of the filaments and Hitomi measurements of the X-ray gas dynamics in Perseus is also explored

    Active Tension Network model suggests an exotic mechanical state realized in epithelial tissues.

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    Mechanical interactions play a crucial role in epithelial morphogenesis, yet understanding the complex mechanisms through which stress and deformation affect cell behavior remains an open problem. Here we formulate and analyze the Active Tension Network (ATN) model, which assumes that the mechanical balance of cells within a tissue is dominated by cortical tension and introduces tension-dependent active remodeling of the cortex. We find that ATNs exhibit unusual mechanical properties. Specifically, an ATN behaves as a fluid at short times, but at long times supports external tension like a solid. Furthermore, an ATN has an extensively degenerate equilibrium mechanical state associated with a discrete conformal - "isogonal" - deformation of cells. The ATN model predicts a constraint on equilibrium cell geometries, which we demonstrate to approximately hold in certain epithelial tissues. We further show that isogonal modes are observed in the fruit y embryo, accounting for the striking variability of apical areas of ventral cells and helping understand the early phase of gastrulation. Living matter realizes new and exotic mechanical states, the study of which helps to understand biological phenomena

    NHS waiting lists and evidence of national or local failure: analysis of health service data.

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    OBJECTIVES: To investigate the national distribution of prolonged waiting for elective day case and inpatient surgery, and to examine associations of prolonged waiting with markers of NHS capacity, activity in the independent sector, and need. SETTING: NHS hospital trusts in England. POPULATION: People waiting for elective treatment in the specialties of general surgery; ear, nose and throat surgery; ophthalmic surgery; and trauma and orthopaedic surgery. MAIN OUTCOME MEASURE: Numbers of people waiting six months or longer (prolonged waiting). Characteristics of trusts with large numbers waiting six months or longer were examined by using logistic regression. RESULTS: The distribution of numbers of people waiting for day case or elective surgery in all the specialties examined was highly positively skewed. Between 52% and 83% of patients waiting longer than six months in the specialties studied were found in one quarter of trusts, which in turn contributed 23-45% of the national throughput specific to the specialty. In general, there was little evidence to show that capacity (measured by numbers of operating theatres, dedicated day case theatres, available beds, and bed occupancy rate) or independent sector activity were associated with prolonged waiting, although exceptions were noted for individual specialties. There was consistent evidence showing an increase in prolonged waiting, with increased numbers of anaesthetists across all specialties and with increased bed occupancy rates for ear, nose and throat surgery. Markers of greater need for health care, such as deprivation score and rate of limiting long term illness, were inversely associated with prolonged waiting. CONCLUSION: In most instances, substantial numbers of patients waiting unacceptably long periods for elective surgery were limited to a small number of hospitals. Little and inconsistent support was found for associations of prolonged waiting with markers of capacity, independent sector activity, or need in the surgical specialties examined

    Coherent motion of stereocilia assures the concerted gating of hair-cell transduction channels

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    The hair cell's mechanoreceptive organelle, the hair bundle, is highly sensitive because its transduction channels open over a very narrow range of displacements. The synchronous gating of transduction channels also underlies the active hair-bundle motility that amplifies and tunes responsiveness. The extent to which the gating of independent transduction channels is coordinated depends on how tightly individual stereocilia are constrained to move as a unit. Using dual-beam interferometry in the bullfrog's sacculus, we found that thermal movements of stereocilia located as far apart as a bundle's opposite edges display high coherence and negligible phase lag. Because the mechanical degrees of freedom of stereocilia are strongly constrained, a force applied anywhere in the hair bundle deflects the structure as a unit. This feature assures the concerted gating of transduction channels that maximizes the sensitivity of mechanoelectrical transduction and enhances the hair bundle's capacity to amplify its inputs.Comment: 24 pages, including 6 figures, published in 200

    Limit on the mass of a long-lived or stable gluino

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    We reinterpret the generic CDF charged massive particle limit to obtain a limit on the mass of a stable or long-lived gluino. Various sources of uncertainty are examined. The RR-hadron spectrum and scattering cross sections are modeled based on known low-energy hadron physics and the resultant uncertainties are quantified and found to be small compared to uncertainties from the scale dependence of the NLO pQCD production cross sections. The largest uncertainty in the limit comes from the unknown squark mass: when the squark -- gluino mass splitting is small, we obtain a gluino mass limit of 407 GeV, while in the limit of heavy squarks the gluino mass limit is 397 GeV. For arbitrary (degenerate) squark masses, we obtain a lower limit of 322 GeV on the gluino mass. These limits apply for any gluino lifetime longer than 30\sim 30 ns, and are the most stringent limits for such a long-lived or stable gluino.Comment: 15 pages, 5 figures, accepted for publication in JHE
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