990 resultados para Doty, Alan
Consumption of fa cai Nostoc soup: A Potential for BMAA exposure from Nostoc cyanobacteria in China?
Resumo:
Grown in arid regions of western China the cyanobacterium Nostoc flagelliforme - called fa cai in Mandarin and fat choy in Cantonese - is wild-harvested and used to make soup consumed during New Year's celebrations. High prices, up to $125 USD/kg, led to overharvesting in Inner Mongolia, Ningxia, Gansu, Qinghai, and Xinjiang. Degradation of arid ecosystems, desertification, and conflicts between Nostoc harvesters and Mongol herdsman concerned the Chinese environmental authorities, leading to a government ban of Nostoc commerce. This ban stimulated increased marketing of a substitute made from starch. We analysed samples purchased throughout China as well as in Chinese markets in the United States and the United Kingdom. Some were counterfeits consisting of dyed starch noodles. A few samples from California contained Nostoc flagelliforme but were adulterated with starch noodles. Other samples, including those from the United Kingdom, consisted of pure Nostoc flagelliforme. A recent survey of markets in Cheng Du showed no real Nostoc flagelliforme to be marketed. Real and artificial fa cai differ in the presence of beta-N-methylamino-L-alanine (BMAA). Given its status as a high-priced luxury food, the government ban on collection and marketing, and the replacement of real fa cai with starch substitutes consumed only on special occasions, it is anticipated that dietary exposure to BMAA from fa cai will be reduced in the future in China.
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Based on its characteristic oral apparatus, the ciliate subclass Peritrichia has long been recognized as a monophyletic assemblage composed of the orders Mobilida and Sessilida. Following the application of molecular methods, the monophyly of Peritrichia has recently been questioned. We investigated the phylogenetic relationships of the peritrichous ciliates based on four further complete small subunit ribosomal RNA sequences of mobilids, namely Urceolaria urechi, Trichodina meretricis, Trichodina sinonovaculae, and Trichodina ruditapicis. In all phylogenetic trees, the mobilids never clustered with the sessilids, but instead formed a monophyletic assemblage related to the peniculines. By contrast, the sessilids formed a sister clade with the hymenostomes at a terminal position within the Oligohymenophorea. We therefore formally separate the mobilids from the sessilids (Peritrichia sensu stricto) and establish a new subclass, Mobilia Kahl, 1933, which contains the order Mobilida Kahl, 1933. We argue that the oral apparatus in the mobilians and sessilid peritrichs is a homoplasy, probably due to convergent evolution driven by their similar life-styles and feeding strategies. Morphologically, the mobilians are distinguished from all other oligohymenophoreans by the presence of the adhesive disc, this character being a synapomorphy for the Mobilia.
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The infraciliature and myoneme system of Campanella umbellaria were revealed using the protargol impregnation technique. The main characteristics of the infraciliature are the peristomial ciliary rows (haplokinety and polykineties), which make four and a half turns around the peristomial disc before plunging into the infundibulum, and the aboral infraciliature, which is made up of the aboral ciliary wreath (trochal band) and the scopula. The myoneme system is composed of: 1) longitudinal fibers, which include 60-84 (mean 72.3) short longitudinal fibers, 40-56 (mean 45.8) medium-length longitudinal fibers, and numerous long longitudinal fibers; and 2) circular fibers, which include 8-12 (mean 9.3) peristomial ring fibers, linking fibers, support fibers, and peristomial disc fibers. The various fibers in C. umbellaria are interconnected to form a single myoneme system that may act as a cell skeleton as well as providing the mechanism by which the zooid contracts and relaxes. (C) 2004 Wiley-Liss, Inc.
Resumo:
The temperature and pressure dependences of band-edge photo luminescence from ZnO microrods have been investigated. The energy separation between the free exciton (FX) and its first order phonon replica (FX-1LO) decreases at a rate of k(B)T with increasing temperature. The intensity ratio of the FX-1LO to the bound exciton (BX) emission is found to decrease slightly with increasing pressure. All of the exciton emission peaks show a blue shift with increasing pressure. The pressure coefficient of the FX transition, longitudinal optical (LO) phonon energy, and binding energy of BX are estimated to be 21.4, 0.5, and 0.9 meV/GPa, respectively. (c) 2006 Elsevier Ltd. All rights reserved.
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The biaxial piezospectroscopic coefficient (i.e., the rate of spectral shift with stress) of the electrostimulated near-band-gap luminescence of gallium nitride (GaN) was determined as Pi=-25.8 +/- 0.2 meV/GPa. A controlled biaxial stress field was applied on a hexagonal GaN film, epitaxially grown on (0001) sapphire using a ball-on-ring biaxial bending jig, and the spectral shift of the electrostimulated near-band-gap was measured in situ in the scanning electron microscope. This calibration method can be useful to overcome the lack of a bulk crystal of relatively large size for more conventional uniaxial bending calibrations, which has so far hampered the precise determination of the piezospectroscopic coefficient of GaN. The main source of error involved with the present calibration method is represented by the selection of appropriate values for the elastic stiffness constants of both film and substrate. The ball-on-ring calibration method can be generally applied to directly determine the biaxial-stress dependence of selected cathodoluminescence bands of epilayer/substrate materials without requiring separation of the film from the substrate. (c) 2006 American Institute of Physics.
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Inferring how the Pleistocene climate oscillations have repopulated the extant population structure of Chondrus crispus Stackh. in the North Atlantic Ocean is important both for our understanding of the glacial episode promoting diversification and for the conservation and development of marine organisms. C. crispus is an ecologically and commercially important red seaweed with broad distributions in the North Atlantic. Here, we employed both partial mtDNA Cox1 and nrDNA internal transcribed spacer region 2 (ITS2) sequences to explore the genetic structure of 17 C. crispus populations from this area. Twenty-eight and 30 haplotypes were inferred from these two markers, respectively. Analysis of molecular variance (AMOVA) and of the population statistic Theta(ST) not only revealed significant genetic structure within C. crispus populations but also detected significant levels of genetic subdivision among and within populations in the North Atlantic. On the basis of high haplotype diversity and the presence of endemic haplotypes, we postulate that C. crispus had survived in Pleistocene glacial refugia in the northeast Atlantic, such as the English Channel and the northwestern Iberian Peninsula. We also hypothesize that C. crispus from the English Channel refugium repopulated most of northeastern Europe and recolonized northeastern North America in the Late Pleistocene. The observed phylogeographic pattern of C. crispus populations is in agreement with a scenario in which severe Quaternary glaciations influenced the genetic structure of North Atlantic marine organisms with contiguous population expansion and locally restricted gene flow coupled with a transatlantic dispersal in the Late Pleistocene.
Resumo:
Eighteen isolates of the red algae Chondrus crispus were collected from Northern Atlantic sites, together with C. ocellatus, C. yendoi and C. pinnulatus from the North Pacific. The nuclear rDNA internal transcribed spacer (ITS) was sequenced and compared, spanning both the ITS regions and the 5.8S rRNA gene. Percentage of nucleotide variation for C. crispus ranged from 0.3% to 4.0%. Phylogenetic analyses were performed using maximum parsimony (MP), neighbor-joining (NJ) and minimum evolution methods. They showed that two main clades existed within the C. crispus samples examined and that suggested C. crispus had a single Atlantic origin. The clustering however did not follow the geographic origin. We hypothesized that the current distribution of C. crispus populations might be a result of three main factors: temperature boundaries, paleoclimate and paleoceanography. ITS data exhibited abundant molecular information not only for phylogeographical investigation but also for systematics studies.
Resumo:
ISSR analysis was used to investigate genetic variations of 184 haploid and diploid samples from nine North Atlantic Chondrus crispus Stackhouse populations and one outgroup Yellow Sea Chondrus ocellatus Holmes population. Twenty-two of 50 primers were selected and 163 loci were scored for genetic diversity analysis. Genetic diversity varied among populations, percentage of polymorphic bands (PPB) ranged from 27.0 to 55.8%, H(Nei's genetic diversity) ranged from 0.11 to 0.20 and I(Shannon's information index) ranged from 0.16 to 0.30. Estimators PPB, H and I had similar values in intra-population genetic diversity, regardless of calculation methods. Analysis of molecular variance (AMOVA) apportioned inter-population and intra-population variations for C crispus, showing more genetic variance (56.5%) occurred in intra-population, and 43.5% variation among nine populations. The Mantel test suggested that genetic differentiation between nine C. crispus populations was closely related with geographic distances (R = 0.78, P = 0.002). Results suggest that, on larger distance scale (ca. > 1000 km), ISSR analysis is useful for determining genetic differentiations of C crispus populations including morphologically inseparable haploid and diploid individuals. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
Humans recognize optical reflectance properties of surfaces such as metal, plastic, or paper from a single image without knowledge of illumination. We develop a machine vision system to perform similar recognition tasks automatically. Reflectance estimation under unknown, arbitrary illumination proves highly underconstrained due to the variety of potential illumination distributions and surface reflectance properties. We have found that the spatial structure of real-world illumination possesses some of the statistical regularities observed in the natural image statistics literature. A human or computer vision system may be able to exploit this prior information to determine the most likely surface reflectance given an observed image. We develop an algorithm for reflectance classification under unknown real-world illumination, which learns relationships between surface reflectance and certain features (statistics) computed from a single observed image. We also develop an automatic feature selection method.
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This paper describes a machine vision system that classifies reflectance properties of surfaces such as metal, plastic, or paper, under unknown real-world illumination. We demonstrate performance of our algorithm for surfaces of arbitrary geometry. Reflectance estimation under arbitrary omnidirectional illumination proves highly underconstrained. Our reflectance estimation algorithm succeeds by learning relationships between surface reflectance and certain statistics computed from an observed image, which depend on statistical regularities in the spatial structure of real-world illumination. Although the algorithm assumes known geometry, its statistical nature makes it robust to inaccurate geometry estimates.
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Two methods of obtaining approximate solutions to the classic General Job-shop Scheduling Program are investigated. The first method is iterative. A sampling of the solution space is used to decide which of a collection of space pruning constraints are consistent with "good" schedules. The selected space pruning constraints are then used to reduce the search space and the sampling is repeated. This approach can be used either to verify whether some set of space pruning constraints can prune with discrimination or to generate solutions directly. Schedules can be represented as trajectories through a Cartesian space. Under the objective criteria of Minimum maximum Lateness family of "good" schedules (trajectories) are geometric neighbors (reside with some "tube") in this space. This second method of generating solutions takes advantage of this adjacency by pruning the space from the outside in thus converging gradually upon this "tube." One the average this methods significantly outperforms an array of the Priority Dispatch rules when the object criteria is that of Minimum Maximum Lateness. It also compares favorably with a recent relaxation procedure.
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Cryotherapy is widely used in rehabilitation; however, its effectiveness after anterior cruciate ligament (ACL) reconstruction remains uncertain. To investigate the effectiveness and safety of cryotherapy following ACL reconstruction through a systematic review, randomized and quasi-randomized clinical trials were searched in the databases: MEDLINE, EMBASE, CENTRAL PEDro, SportDiscus, CINAHL, LILACS (June 2013). the primary outcomes measures were pain, edema and adverse events; the secondary outcomes were knee function, analgesic medication use, range of motion, blood loss, hospital stay, quality of life and patient satisfaction. the methodological quality of studies was evaluated using the Cochrane Collaboration risk-of-bias tool. Ten trials (a total of 573 patients) were included. Results of meta-analysis showed that the use of cold compression devices produced a significant reduction in pain scores 48 h after surgery (p < 0.00001), compared to no cryotherapy. the risk for adverse events did not differ between patients receiving cryotherapy versus no treatment (p = 1.00). the limited evidence currently available is insufficient to draw definitive conclusions on the effectiveness of cryotherapy for other outcomes. There is a need for well designed, good quality randomized trials to answer other questions related to this intervention and increase the precision of future systematic reviews. (C) 2014 Elsevier B.V. All rights reserved.
Resumo:
Objective: To develop sedation, pain, and agitation quality measures using process control methodology and evaluate their properties in clinical practice. Design: A Sedation Quality Assessment Tool was developed and validated to capture data for 12-hour periods of nursing care. Domains included pain/discomfort and sedation-agitation behaviors; sedative, analgesic, and neuromuscular blocking drug administration; ventilation status; and conditions potentially justifying deep sedation. Predefined sedation-related adverse events were recorded daily. Using an iterative process, algorithms were developed to describe the proportion of care periods with poor limb relaxation, poor ventilator synchronization, unnecessary deep sedation, agitation, and an overall optimum sedation metric. Proportion charts described processes over time (2 monthly intervals) for each ICU. The numbers of patients treated between sedation-related adverse events were described with G charts. Automated algorithms generated charts for 12 months of sequential data. Mean values for each process were calculated, and variation within and between ICUs explored qualitatively. Setting: Eight Scottish ICUs over a 12-month period. Patients: Mechanically ventilated patients. Interventions: None. Measurements and Main Results: The Sedation Quality Assessment Tool agitation-sedation domains correlated with the Richmond Sedation Agitation Scale score (Spearman [rho] = 0.75) and were reliable in clinician-clinician (weighted kappa; [kappa] = 0.66) and clinician-researcher ([kappa] = 0.82) comparisons. The limb movement domain had fair correlation with Behavioral Pain Scale ([rho] = 0.24) and was reliable in clinician-clinician ([kappa] = 0.58) and clinician-researcher ([kappa] = 0.45) comparisons. Ventilator synchronization correlated with Behavioral Pain Scale ([rho] = 0.54), and reliability in clinician-clinician ([kappa] = 0.29) and clinician-researcher ([kappa] = 0.42) comparisons was fair-moderate. Eight hundred twenty-five patients were enrolled (range, 59-235 across ICUs), providing 12,385 care periods for evaluation (range 655-3,481 across ICUs). The mean proportion of care periods with each quality metric varied between ICUs: excessive sedation 12-38%; agitation 4-17%; poor relaxation 13-21%; poor ventilator synchronization 8-17%; and overall optimum sedation 45-70%. Mean adverse event intervals ranged from 1.5 to 10.3 patients treated. The quality measures appeared relatively stable during the observation period. Conclusions: Process control methodology can be used to simultaneously monitor multiple aspects of pain-sedation-agitation management within ICUs. Variation within and between ICUs could be used as triggers to explore practice variation, improve quality, and monitor this over time
Resumo:
Brown, D.S., Nightingale, R.W., Alexander, D., Schrijver, C.J., Metcalf, T.R., Shine, R.A., Title, A.M. and Wolfson, C.J., 2003, Observations of rotating sunspots from TRACE, Solar Physics, 216, 79-108.