1,833 research outputs found

    High frequency sampling of the 1984 spring bloom within the mid-Atlantic Bight: Synoptic shipboard, aircraft, and in situ perspectives of the SEEP-I experiment

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    Moorings of current meters, thermistors, transmissometers, and fluorometers on the mid-Atlantic shelf, south of Long Island, suggest a cumulative seaward export of perhaps 0.35 g C/sq m/day between the 80 and 120 m isobaths during February-April 1984. Such a horizontal loss of algal carbon over the lower third of the water column would be 23 to 78% of the March-April 1984 primary production. This physical carbon loss is similar to daily grazing losses from zooplankton of 32-40% of the algal fixation of carbon. Metabolic demands of the benthos could be met by just the estimated fecal pellet flux, without direct consumption of algal carbon, while bacterioplankton needs could be served by excretory release of dissolved organic matter during photosynthesis. Sediment traps tethered 10 m off the bottom at the 120 m isobath and 50 m above the 500 m isobath caught as much as 0.16 to 0.26 g C /sq m/day during March-April 1984, in reasonable agreement with the flux estimated from the other moored instruments

    An Experimental And Numerical Study Of Elastic Strain Waves On The Center Line Of A 6061-T6 Aluminum Bar

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    The elastic strain waves resulting from the impact of two 3/4-in-dia 6061-T6 aluminum bars are studied experimentally and analytically. Experimental data are obtained from strain gages on the center line and outer surface of the bar, located at various distances from the impact end of the bar. Experimental data are compared to numerical results obtained from integrating the exact equations of two-dimensional motion. In general, agreement between the numerical and experimental results is very good. © 1972 by ASME

    Remote Detection of Coral \u27Bleaching\u27 Using Pulsed-Laser Fluorescence Spectroscopy

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    Despite their biological and economic importance coral reefs are increasingly threatened by human activities. Recently, \u27bleaching\u27 of reefs, i.e. loss of photosynthetic pigmentation, has occurred at numerous globally-distributed sites. A number of environmental stressors, including increased water temperature, can induce bleaching. Several investigators have suggested that the widespread occurrence of coral bleaching represents an early warning signal of global greenhouse warming. Regardless of the cause, the extent of coral bleaching, both regionally and globally, needs to be documented and monitored. We conducted laboratory studies to evaluate the potential of using remotely-sensed laser-induced fluorescence to monitor coral pigmentation. Five species of Caribbean corals were collected, transported to the laboratory, and maintained in aquaria. Coral samples were irradiated at either 532 nm or 337 nm with pulsed-laser light and spectral scans of fluorescence were collected at 1 nm intervals. Dlstinct chlorophyll fluorescence peaks at 685 and 740 nm were observed in all species examined. In corals exposed to temperature-induced stress, incipient changes In the fluorescence spectra could be detected prior to visible bleaching and coral death. Remotely-measured (aircraft or ship) laser-induced fluorescence provides a potentially useful tool for monitoring the pigmentation status of coral reefs. Field validation will be necessary, but our results suggest that it may be possible to distinguish bleaching, or even partial bleaching, over large geographical areas with sensitivity and rapidity

    At what time does a quantum experiment have a result?

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    This paper provides a general method for defining a generalized quantum observable (or POVM) that supplies properly normalized conditional probabilities for the time of occurrence (i.e., of detection). This method treats the time of occurrence as a probabilistic variable whose value is to be determined by experiment and predicted by the Born rule. This avoids the problematic assumption that a question about the time at which an event occurs must be answered through instantaneous measurements of a projector by an observer, common to both Rovelli (1998) and Oppenheim et al. (2000). I also address the interpretation of experiments purporting to demonstrate the quantum Zeno effect, used by Oppenheim et al. (2000) to justify an inherent uncertainty for measurements of times.Comment: To appear in proceedings of 2015 ETH Zurich Workshop on Time in Physic

    A promoter region that controls basal and elicitor-inducible expression levels of the NADPH: cytochrome P450 reductase gene (Cpr) from Catharanthus roseus binds nuclear factor GT-1

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    NADPH:cytochrome P450 reductase (CPR) is essential for the activation of cytochrome P450 enzymes, which are involved in a wide variety of metabolic pathways in plants, including those related to defence responses. In the subtropical plant Catharanthus roseus several cytochrome P450 enzymes operate in the biosynthesis of defence-related terpenoid indole alkaloids (TIAs). In agreement with the importance of CPR in defence, Cpr mRNA levels in C. roseus were found to be enhanced by fungal elicitor preparations that also induce TIA biosynthesis and P450 gene expression. Here we describe the isolation of a C. roseus genomic DNA clone covering the 5¢ part of the Cpr gene and 1.6-kb of upstream sequences. Mapping of the transcription start site showed the untranslated leader sequence is approximately 280 bp long. To study the control of gene expression by the Cpr promoter, transcriptional fusions between Cpr promoter fragments and the gusA reporter gene were generated and their expression was analyzed in stably transformed tobacco plants. The Cpr promoter fragment extending from )1510 to )8, with respect to the ATG start codon, conferred basal and elicitor-inducible expression on the gusA reporter gene, strongly indicating that the Cpr gene of C. roseus is indeed controlled by this promoter region. Progressive deletion from the 5¢ end of the promoter to position )632 had little e ect on gusA expression. However, deletion to position )366 resulted in a complete loss of basal activity and largely eliminated elicitor-induced expression, indicating that the region from )632 to )366 contains the main transcription-enhancing cis-regulatory sequences. Electrophoretic mobility shift assays with tobacco nuclear extracts showed that binding sites for nuclear factor GT-1 are redundant in the Cpr promoter, but absent from the downstream part of the leader sequence. The presence of strong GT-1 binding sites in the main enhancer region ()632 to )366), is suggestive of a functional role for this factor in basal expression and elicitor responsiveness of the Cpr promoter.info:eu-repo/semantics/publishedVersio

    A promoter region that controls basal and elicitor-inducible expression levels of the NADPH: cytochrome P450 reductase gene (Cpr) from Catharanthus roseus binds nuclear factor GT-1

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    NADPH:cytochrome P450 reductase (CPR) is essential for the activation of cytochrome P450 enzymes, which are involved in a wide variety of metabolic pathways in plants, including those related to defence responses. In the subtropical plant Catharanthus roseus several cytochrome P450 enzymes operate in the biosynthesis of defence-related terpenoid indole alkaloids (TIAs). In agreement with the importance of CPR in defence, Cpr mRNA levels in C. roseus were found to be enhanced by fungal elicitor preparations that also induce TIA biosynthesis and P450 gene expression. Here we describe the isolation of a C. roseus genomic DNA clone covering the 5¢ part of the Cpr gene and 1.6-kb of upstream sequences. Mapping of the transcription start site showed the untranslated leader sequence is approximately 280 bp long. To study the control of gene expression by the Cpr promoter, transcriptional fusions between Cpr promoter fragments and the gusA reporter gene were generated and their expression was analyzed in stably transformed tobacco plants. The Cpr promoter fragment extending from )1510 to )8, with respect to the ATG start codon, conferred basal and elicitor-inducible expression on the gusA reporter gene, strongly indicating that the Cpr gene of C. roseus is indeed controlled by this promoter region. Progressive deletion from the 5¢ end of the promoter to position )632 had little e ect on gusA expression. However, deletion to position )366 resulted in a complete loss of basal activity and largely eliminated elicitor-induced expression, indicating that the region from )632 to )366 contains the main transcription-enhancing cis-regulatory sequences. Electrophoretic mobility shift assays with tobacco nuclear extracts showed that binding sites for nuclear factor GT-1 are redundant in the Cpr promoter, but absent from the downstream part of the leader sequence. The presence of strong GT-1 binding sites in the main enhancer region ()632 to )366), is suggestive of a functional role for this factor in basal expression and elicitor responsiveness of the Cpr promoter.info:eu-repo/semantics/publishedVersio

    Early Service leavers: a study of the factors associated with premature separation from the UK Armed Forces and the mental health of those that leave early.

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    BACKGROUND: Approximately 18,000 personnel leave the UK Armed Forces annually. Those leaving before completing the minimum term of their contracts are called early Service leavers (ESLs). This study aims to identify characteristics associated with being an ESL, and compare the post-discharge mental health of ESLs and other Service leavers (non-ESLs). METHOD: A cross-sectional study used data on ex-Serving UK Armed Forces personnel. ESLs were personnel leaving before completing their 3-4.5 years minimum Service contracts and were compared with non-ESLs. Multivariable logistic regression was used to estimate odds ratios and 95% confidence intervals for the associations between Service leaving status with socio-demographics, military characteristics and mental health outcomes. RESULTS: Of 845 Service leavers, 80 (9.5%) were ESLs. Being an ESL was associated with younger age, female sex, not being in a relationship, lower rank, serving in the Army and with a trend of reporting higher levels of childhood adversity, but not with deployment to Iraq. ESLs were at an increased risk of probable post-traumatic stress disorder (PTSD), common mental disorders, fatigue and multiple physical symptoms, but not alcohol misuse. CONCLUSIONS: The study suggests that operational Service is not a factor causing personnel to become an ESL. Current mental health problems were more commonly reported among ESLs than other Service leavers. There may be a need to target interventions to ESLs on leaving Service to smooth their transition to civilian life and prevent the negative mental health outcomes experienced by ESLs further down the line
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