851 research outputs found

    Uplift and subsidence associated with the great Aceh-Andaman earthquake of 2004

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    Rupture of the Sunda megathrust on 26 December 2004 produced broad regions of uplift and subsidence. We define the pivot line separating these regions as a first step in defining the lateral extent and the downdip limit of rupture during that great M_w ≈ 9.2 earthquake. In the region of the Andaman and Nicobar islands we rely exclusively on the interpretation of satellite imagery and a tidal model. At the southern limit of the great rupture we rely principally on field measurements of emerged coral microatolls. Uplift extends from the middle of Simeulue Island, Sumatra, at ~2.5°N, to Preparis Island, Myanmar (Burma), at ~14.9°N. Thus the rupture is ~1600 km long. The distance from the pivot line to the trench varies appreciably. The northern and western Andaman Islands rose, whereas the southern and eastern portion of the islands subsided. The Nicobar Islands and the west coast of Aceh province, Sumatra, subsided. Tilt at the southern end of the rupture is steep; the distance from 1.5 m of uplift to the pivot line is just 60 km. Our method of using satellite imagery to recognize changes in elevation relative to sea surface height and of using a tidal model to place quantitative bounds on coseismic uplift or subsidence is a novel approach that can be adapted to other forms of remote sensing and can be applied to other subduction zones in tropical regions

    Directed Evolution of Gloeobacter violaceus Rhodopsin Spectral Properties

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    Proton-pumping rhodopsins (PPRs) are photoactive retinal-binding proteins that transport ions across biological membranes in response to light. These proteins are interesting for light-harvesting applications in bioenergy production, in optogenetics applications in neuroscience, and as fluorescent sensors of membrane potential. Little is known, however, about how the protein sequence determines the considerable variation in spectral properties of PPRs from different biological niches or how to engineer these properties in a given PPR. Here we report a comprehensive study of amino acid substitutions in the retinal binding pocket of Gloeobacter violacaeus rhodopsin (GR) that tune its spectral properties. Directed evolution generated 70 GR variants with absorption maxima shifted by up to +/- 80 nm, extending the protein’s light absorption significantly beyond the range of known natural PPRs. While proton pumping activity was disrupted in many of the spectrally shifted variants, we identified single tuning mutations that incurrred blue and red shifts of 42 nm and 22 nm, respectively, that did not disrupt proton pumping. Blue-shifting mutations were distributed evenly along the retinal molecule while red-shifting mutations were clustered near the residue K257, which forms a covalent bond with retinal through a Schiff base linkage. Thirty-four of the identified tuning mutations are not found in known microbial rhodopsins. We discovered a subset of red-shifted GRs that exhibit high levels of fluorescence relative to the wild-type protein

    Fluxional η^3-Allyl Derivatives of ansa-Scandocenes and an ansa-Yttrocene. Measurements of the Barriers for the η^3 to η^1 Process as an Indicator of Olefin Binding Energy to d^0 Metallocenes

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    Variable-temperature ^1H NMR spectroscopy indicates fluxional behavior for a number of group 3 metallocene allyl complexes. Spectral simulations and line shape analyses for the variable-temperature spectra indicate an allyl rearrangement mechanism involving rate-determining carbon−carbon double-bond dissociation from the metal center, i.e. an η^3 to η^1 change in coordination. Activation barriers to olefin dissociation have been determined for (η^5-C_5Me_5)_2Sc(η^3-C^3H^5), meso-Me^2Si(η^5-3-CMe^3-C_5H_3)_2Sc(η^3-C_3H_5), meso-Me_2Si[η^5-2,4-(CHMe_2)_2-C_5H_2]_2Sc(η^3-C_3H_5), meso-Me_2Si{η^5-3-[2-(2-Me)-adamantyl]-C_5H_3}_2Sc(η^3-C_3H_5), meso-Me_2Si{η^5-3-[2-(2-Me)-adamantyl]-C_5H_3}_2Y(η^3-C_3H_5), rac-Me_2Si[η^5-2,4-(CHMe_2)_2-C_5H_2]_2Sc(η^3-C_3H_5)), and R-(C_(20)H_(12)O_2)Si(η^5-2-SiMe_3-4-CMe_3-C_5H_2)_2Sc(η^3-C_3H_5):  ΔG^⧧ = 11−16 kcal mol^(-1) at ca. 300−350 K. Donor solvents do not significantly affect the rate of olefin dissociation. A second rearrangement mechanism that involves 180° rotation of the η^3-C_3H_5 moiety has been found to operate in those metallocenes whose ancillary ligand arrays adopt rigid meso geometries. Line shape analysis indicates that the rate of η^3-C_3H_5 rotation is generally more than 1 order of magnitude faster than olefin dissociation for a given meso metallocene. The data do not allow unambiguous assessments of the mechanism(s) for the fluxional behavior for the allyl derivatives of the racemic metallocenes. An X-ray structure determination for rac-Me_2Si[η^5-C_5H_2-2,4-(CHMe_2)_2]_2Sc(η^3-C_3H_5) has been carried out

    Search for Fractional Charges in Water

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    Results are presented from a search for fractional charges in water from a variety of natural sources. About 30 000 water drops have been measured, comprising 51 μg of water and dissolved materials. No evidence for fractional charge was seen

    Transgenic increases in seed oil content are associated with the differential expression of novel Brassica-specific transcripts

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    <p>Abstract</p> <p>Background</p> <p>Seed oil accumulates primarily as triacylglycerol (TAG). While the biochemical pathway for TAG biosynthesis is known, its regulation remains unclear. Previous research identified microsomal diacylglycerol acyltransferase 1 (DGAT1, EC 2.3.1.20) as controlling a rate-limiting step in the TAG biosynthesis pathway. Of note, overexpression of <it>DGAT1 </it>results in substantial increases in oil content and seed size. To further analyze the global consequences of manipulating <it>DGAT1 </it>levels during seed development, a concerted transcriptome and metabolome analysis of transgenic <it>B. napus </it>prototypes was performed.</p> <p>Results</p> <p>Using a targeted <it>Brassica </it>cDNA microarray, about 200 genes were differentially expressed in two independent transgenic lines analyzed. Interestingly, 24–33% of the targets showing significant changes have no matching gene in <it>Arabidopsis </it>although these represent only 5% of the targets on the microarray. Further analysis of some of these novel transcripts indicated that several are inducible by ABA in microspore-derived embryos. Of the 200 <it>Arabidopsis </it>genes implicated in lipid biology present on the microarray, 36 were found to be differentially regulated in DGAT transgenic lines. Furthermore, kinetic reverse transcriptase Polymerase Chain Reaction (k-PCR) analysis revealed up-regulation of genes encoding enzymes of the Kennedy pathway involved in assembly of TAGs. Hormone profiling indicated that levels of auxins and cytokinins varied between transgenic lines and untransformed controls, while differences in the pool sizes of ABA and catabolites were only observed at later stages of development.</p> <p>Conclusion</p> <p>Our results indicate that the increased TAG accumulation observed in transgenic <it>DGAT1 </it>plants is associated with modest transcriptional and hormonal changes during seed development that are not limited to the TAG biosynthesis pathway. These might be associated with feedback or feed-forward effects due to altered levels of DGAT1 activity. The fact that a large fraction of significant amplicons have no matching genes in <it>Arabidopsis </it>compromised our ability to draw concrete inferences from the data at this stage, but has led to the identification of novel genes of potential interest.</p

    Hematopoietic Cell Transplant and Use of Massage for Improved Symptom Management: Results from a Pilot Randomized Control Trial

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    Background. Pediatric hematopoietic cell transplant (HCT) is a lifesaving treatment that often results in physical and psychological discomfort. An acupressure-massage intervention may improve symptom management in this setting. Methods. This randomized controlled pilot trial compared a combined massage-acupressure intervention to usual care. Children were offered three practitioner-provided sessions per week throughout hospitalization. Parents were trained to provide additional acupressure as needed. Symptoms were assessed using nurses' reports and two questionnaires, the behavioral affective and somatic experiences scale and the Peds quality of life cancer module. Results. We enrolled 23 children, ages 5 to 18. Children receiving the intervention reported fewer days of mucositis (Hedges' g effect size ES = 0.63), lower overall symptom burden (ES = 0.26), feeling less tired and run-down (ES = 0.86), having fewer moderate/severe symptoms of pain, nausea, and fatigue (ES = 0.62), and less pain (ES = 0.42). The intervention group showed trends toward increasing contentness/serenity (ES = +0.50) and decreasing depression (ES = −0.45), but not decreased anxiety (ES = +0.42). Differences were not statistically significant. Discussion. Feasibility of studying massage-acupressure was established in children undergoing HCT. Larger studies are needed to test the efficacy of such interventions in reducing HCT-associated symptoms in children

    Linkages between Cigarette Smoking Outcome Expectancies and Negative Emotional Vulnerability

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    The present investigation examined whether smoking outcome expectancies, as measured by the Smoking Consequences Questionnaire (SCQ; [Brandon, T.H., & Baker, T.B., (1991). The Smoking Consequences Questionnaire: The subjective expected utility of smoking in college students. Psychological Assessment, 3, 484–491.]), were incrementally related to emotional vulnerability factors among an adult sample of 202 daily cigarette smokers (44.6% women; Mage= 23.78 years, SD = 9.69 years). After controlling for cigarettes smoked/day, past 30-day marijuana use, current alcohol consumption, and coping style, negative reinforcement/negative affect reduction outcome expectancies were significantly associated with greater levels of negative affectivity, emotional dysregulation, and anxiety sensitivity. The observed effects for negative reinforcement/negative affect reduction also were independent of shared variance with other outcome expectancies. Negative personal consequences outcome expectancies were significantly and incrementally related to anxiety sensitivity, but not negative affectivity or emotional dysregulation. Findings are discussed in terms of the role of negative reinforcement/ negative affect reduction smoking outcome expectancies and clinically-relevant negative emotional vulnerability for better understanding cigarette smoking-negative mood problem

    Assessing methods for dealing with treatment switching in clinical trials: A follow-up simulation study

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    When patients randomised to the control group of a randomised controlled trial are allowed to switch onto the experimental treatment, intention-to-treat analyses of the treatment effect are confounded because the separation of randomised groups is lost. Previous research has investigated statistical methods that aim to estimate the treatment effect that would have been observed had this treatment switching not occurred and has demonstrated their performance in a limited set of scenarios. Here, we investigate these methods in a new range of realistic scenarios, allowing conclusions to be made based upon a broader evidence base. We simulated randomised controlled trials incorporating prognosis-related treatment switching and investigated the impact of sample size, reduced switching proportions, disease severity, and alternative data-generating models on the performance of adjustment methods, assessed through a comparison of bias, mean squared error, and coverage, related to the estimation of true restricted mean survival in the absence of switching in the control group. Rank preserving structural failure time models, inverse probability of censoring weights, and two-stage methods consistently produced less bias than the intentionto-treat analysis. The switching proportion was confirmed to be a key determinant of bias: sample size and censoring proportion were relatively less important. It is critical to determine the size of the treatment effect in terms of an acceleration factor (rather than a hazard ratio) to provide information on the likely bias associated with rank-preserving structural failure time model adjustments. In general, inverse probability of censoring weight methods are more volatile than other adjustment methods

    Search for Fractional Charges Produced in Heavy-Ion Collisions at 1.9 GeV/nucleon

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    An experiment was performed to capture fractionally charged particles produced in heavy-ion collisions and to concentrate them in samples suitable for analysis by various techniques. Two of the samples so produced have been searched, with use of an automated version of Millikan\u27s oil-drop apparatus. The beam was 56Fe at 1.9 GeV/nucleon, incident on a lead target. Less than one fractional charge per 1.0× 104 Fe-Pb collisions was found to be produced, and, with further assumptions, less than one per 2.0× 106 collisions
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