Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
1.
Sensors (Basel) ; 22(23)2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36502080

RESUMO

Seismic velocities and elastic moduli of rocks are known to vary significantly with applied stress, which indicates that these materials exhibit nonlinear elasticity. Monochromatic waves in nonlinear elastic media are known to generate higher harmonics and combinational frequencies. Such effects have the potential to be used for broadening the frequency band of seismic sources, characterization of the subsurface, and safety monitoring of civil engineering infrastructure. However, knowledge on nonlinear seismic effects is still scarce, which impedes the development of their practical applications. To explore the potential of nonlinear seismology, we performed three experiments: two in the field and one in the laboratory. The first field experiment used two vibroseis sources generating signals with two different monochromatic frequencies. The second field experiment used a surface orbital vibrator with two eccentric motors working at different frequencies. In both experiments, the generated wavefield was recorded in a borehole using a fiber-optic distributed acoustic sensing cable. Both experiments showed combinational frequencies, harmonics, and other intermodulation products of the fundamental frequencies both on the surface and at depth. Laboratory experiments replicated the setup of the field test with vibroseis sources and showed similar nonlinear combinations of fundamental frequencies. Amplitudes of the nonlinear signals observed in the laboratory showed variation with the saturating fluid. These results confirm that nonlinear components of the wavefield propagate as body waves, are likely to generate within rock formations, and can be potentially used for reservoir fluid characterization.


Assuntos
Acústica , Planeta Terra , Elasticidade , Módulo de Elasticidade
2.
JAMA Netw Open ; 3(8): e2010779, 2020 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-32845326

RESUMO

Importance: The risk of death from acute pulmonary embolism can range as high as 15%, depending on patient factors at initial presentation. Acute treatment decisions are largely based on an estimate of this mortality risk. Objective: To assess the performance of risk assessment scores in a modern, US cohort of patients with acute pulmonary embolism. Design, Setting, and Participants: This multicenter cohort study was conducted between October 2016 and October 2017 at 8 hospitals participating in the Pulmonary Embolism Response Team (PERT) Consortium registry. Included patients were adults who presented with acute pulmonary embolism and had sufficient information in the medical record to calculate risk scores. Data analysis was performed from March to May 2020. Main Outcomes and Measures: All-cause mortality (7- and 30-day) and associated discrimination were assessed by the area under the receiver operator curve (AUC). Results: Among 416 patients with acute pulmonary embolism (mean [SD] age, 61.3 [17.6] years; 207 men [49.8%]), 7-day mortality in the low-risk groups ranged from 1.3% (1 patient) to 3.1% (4 patients), whereas 30-day mortality ranged from 2.6% (1 patient) to 10.2% (13 patients). Among patients in the highest-risk groups, the 7-day mortality ranged from 7.0% (18 patients) to 16.3% (7 patients), whereas 30-day mortality ranged from 14.4% (37 patients) to 26.3% (26 patients). Each of the risk stratification tools had modest discrimination for 7-day mortality (AUC range, 0.616-0.666) with slightly lower discrimination for 30-day mortality (AUC range, 0.550-0.694). Conclusions and Relevance: These findings suggest that commonly used risk tools for acute pulmonary embolism have modest estimating ability. Future studies to develop and validate better risk assessment tools are needed.


Assuntos
Embolia Pulmonar/mortalidade , Medição de Risco/métodos , Medição de Risco/normas , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Embolia Pulmonar/terapia
4.
Hosp Pract (1995) ; 45(3): 76-80, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28325091

RESUMO

OBJECTIVES: Pulmonary embolism response teams (PERT) are developing rapidly to operationalize multi-disciplinary care for acute pulmonary embolism patients. Our objective is to describe the core components of PERT necessary for newly developing programs. METHODS: An online organizational survey of active National PERT™ Consortium members was performed between April and June 2016. Analysis, including descriptive statistics and Kruskal-Wallis tests, was performed on centers self-reporting a fully operational PERT program. RESULTS: The survey response rate was 80%. Of the 31 institutions that responded (71% academic), 19 had fully functioning PERT programs. These programs were run by steering committees (17/19, 89%) more often than individual physicians (2/19, 11%). Most PERT programs involved 3-5 different specialties (14/19, 74%), which did not vary based on hospital size or academic affiliation. Of programs using multidisciplinary discussions, these occurred via phone or conference call (12/18, 67%), with a minority of these utilizing 'virtual meeting' software (2/12, 17%). Guidelines for appropriate activations were provided at 16/19 (84%) hospitals. Most PERT programs offered around-the-clock catheter-based or surgical care (17/19, 89%). Outpatient follow up usually occurred in personal physician clinics (15/19, 79%) or dedicated PERT clinics (9/19, 47%), which were only available at academic institutions. CONCLUSIONS: PERT programs can be implemented, with similar structures, at small and large, community and academic medical centers. While all PERT programs incorporate team-based multi-disciplinary care into their core structure, several different models exist with varying personnel and resource utilization. Understanding how different PERT programs impact clinical care remains to be investigated.


Assuntos
Equipe de Assistência ao Paciente/organização & administração , Embolia Pulmonar/tratamento farmacológico , Terapia Trombolítica/métodos , Centros Médicos Acadêmicos/organização & administração , Fibrinolíticos/administração & dosagem , Número de Leitos em Hospital , Humanos , Medicina , Trombectomia/métodos , Filtros de Veia Cava
6.
Am Heart J ; 166(1): 134-41, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23816032

RESUMO

BACKGROUND: Women presenting with signs and symptoms of myocardial ischemia frequently have no or nonobstructive coronary artery disease (CAD). OBJECTIVE: This study aimed to investigate the associations between angiographic measures and longer-term clinical outcomes among women with signs and symptoms of ischemia referred for coronary angiography. METHODS: A prospective cohort analysis of women referred for coronary angiography and enrolled in the National Heart, Lung, and Blood Institute-sponsored WISE was performed. An angiographic severity score was prospectively developed, assigning points for any stenosis weighted by stenosis severity, location, and collaterals and was then tested for prediction for adverse outcome in 917 women, over a median of 9.3 years. SETTING: The study was conducted in referral centers. PATIENTS: Women with signs and/or symptoms of myocardial ischemia referred for coronary angiography were consecutively consented and enrolled in a prospective study. MAIN OUTCOME MEASURES: Main outcomes included first occurrence of cardiovascular death or nonfatal myocardial infarction. Hospitalization for angina was a secondary outcome. RESULTS: Cardiovascular death or myocardial infarction at 10 years occurred in 6.7%, 12.8%, and 25.9% of women with no, nonobstructive, and obstructive CAD (P < .0001), respectively. Cumulative 10-year cardiovascular death or myocardial infarction rates showed progressive, near-linear increases for each WISE CAD severity score range of 5, 5.1 to 10, 10.1 to 20, 20.1 to 50, and >50. The optimal threshold in the WISE severity score classifications for predicting cardiovascular mortality was >10 (eg, 5.0-10 vs 10.1-89), with both a sensitivity and specificity of 0.64 and an area under the curve of 0.64 (P = .02, 95% CI 0.59-0.68). CONCLUSIONS: Among women with signs and symptoms of ischemia, nonobstructive CAD is common and associated with adverse outcomes over the longer term. The new WISE angiographic score appears to be useful for risk prediction in this population.


Assuntos
Angiografia Coronária , Doença da Artéria Coronariana/diagnóstico por imagem , Isquemia Miocárdica/diagnóstico por imagem , National Heart, Lung, and Blood Institute (U.S.) , Doença da Artéria Coronariana/epidemiologia , Feminino , Seguimentos , Humanos , Incidência , Pessoa de Meia-Idade , Isquemia Miocárdica/epidemiologia , Prognóstico , Estudos Prospectivos , Fatores de Risco , Taxa de Sobrevida/tendências , Síndrome , Fatores de Tempo , Estados Unidos/epidemiologia
7.
Environ Sci Technol ; 46(20): 11220-6, 2012 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-23020626

RESUMO

A remotely controlled autonomous method for long-term high-frequency sampling of environmental waters in remote locations is described. The method which preserves sample integrity of dissolved trace metals and major ions for month-long periods employs a gravitational filtration system (GFS) that separates dissolved and particulate phases as samples are collected. The key elements of GFS are (1) a modified "air-outlet" filter holder to maximize filtration rate and thus minimize filtration artifacts; and (2) the direct delivery of filtrate to dedicated bottle sets for specific analytes. Depth and screen filter types were evaluated with depth filters showing best performance. GFS performance is validated using ground, stream, and estuary waters. Over 30 days of storage, samples with GFS treatment had average recoveries of 95 ± 19% and 105 ± 7% of Fe and Mn, respectively; without GFS treatment, average recoveries were only 16% and 18%. Dissolved major cations K, Mg, and Na were stable independent of collection methodology, whereas Ca in some groundwater samples decreased up to 42% without GFS due to CaCO(3) precipitation. In-field performance of GFS equipped autosamplers is demonstrated using ground and streamwater samples collected at the Angelo Coast Range Reserve, California from October 3 to November 4 2011.


Assuntos
Monitoramento Ambiental/instrumentação , Metais/análise , Poluentes Químicos da Água/análise , California , Monitoramento Ambiental/métodos , Filtração/instrumentação
8.
Dev Comp Immunol ; 32(6): 608-12, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18164761

RESUMO

Toll-like receptors (TLRs) are an important part of the innate immunity system and are found throughout the animal kingdom, but have not yet been reported in annelids. We searched shotgun reads of the genomes of the leech Helobdella and polychaete Capitella for TLR homologs. We found 105 TLR homologs in Capitella and 16 in Helobdella. The deduced phylogeny of these sequences, together with TLRs from other animal phyla, reveals three major clades. One clade consists of a mixture of both vertebrates and invertebrates, including sequences from Capitella and Helobdella, while the other two clades contain only invertebrate TLRs.


Assuntos
Anelídeos/genética , Anelídeos/imunologia , Receptores Toll-Like/genética , Receptores Toll-Like/imunologia , Animais , Anelídeos/metabolismo , Evolução Molecular , Imunidade Inata , Comunicação Parácrina , Filogenia , Alinhamento de Sequência , Análise de Sequência de DNA , Receptor 2 Toll-Like/genética , Receptor 2 Toll-Like/metabolismo , Receptores Toll-Like/metabolismo
9.
Plant Mol Biol ; 59(2): 309-22, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16247559

RESUMO

Lack of complete chloroplast genome sequences is still one of the major limitations to extending chloroplast genetic engineering technology to useful crops. Therefore, we sequenced the soybean chloroplast genome and compared it to the other completely sequenced legumes, Lotus and Medicago. The chloroplast genome of Glycine is 152,218 basepairs (bp) in length, including a pair of inverted repeats of 25,574 bp of identical sequence separated by a small single copy region of 17,895 bp and a large single copy region of 83,175 bp. The genome contains 111 unique genes, and 19 of these are duplicated in the inverted repeat (IR). Comparisons of Glycine, Lotus and Medicago confirm the organization of legume chloroplast genomes based on previous studies. Gene content of the three legumes is nearly identical. The rpl22 gene is missing from all three legumes, and Medicago is missing rps16 and one copy of the IR. Gene order in Glycine, Lotus, and Medicago differs from the usual gene order for angiosperm chloroplast genomes by the presence of a single, large inversion of 51 kilobases (kb). Detailed analyses of repeated sequences indicate that many of the Glycine repeats that are located in the intergenic spacer regions and introns occur in the same location in the other legumes and in Arabidopsis, suggesting that they may play some functional role. The presence of small repeats of psbA and rbcL in legumes that have lost one copy of the IR indicate that this loss has only occurred once during the evolutionary history of legumes.


Assuntos
Cloroplastos/genética , Genes de Plantas/genética , Genoma de Planta , Glycine max/genética , Sequência de Bases , Ordem dos Genes/genética , Genômica , Dados de Sequência Molecular , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico
10.
Plant Mol Biol ; 54(6): 911-29, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15604659

RESUMO

Cotton fibers are single-celled seed trichomes of major economic importance. Factors that regulate the rate and duration of cell expansion control fiber morphology and important agronomic traits. For genetic characterization of rapid cell elongation in cotton fibers, approximately 14,000 unique genes were assembled from 46,603 expressed sequence tags (ESTs) from developmentally staged fiber cDNAs of a cultivated diploid species ( Gossypium arboreum L.). Conservatively, the fiber transcriptome represents 35-40% of the genes in the cotton genome. In silico expression analysis revealed that rapidly elongating fiber cells exhibit significant metabolic activity, with the bulk of gene transcripts, represented by three major functional groups - cell wall structure and biogenesis, the cytoskeleton and energy/carbohydrate metabolism. Oligonucleotide microarrays revealed dynamic changes in gene expression between primary and secondary cell wall biogenesis showing that fiber genes in the dbEST are highly stage-specific for cell expansion - a conclusion supported by the absence of known secondary cell wall-specific genes from our fiber dbEST. During the developmental switch from primary to secondary cell wall syntheses, 2553 "expansion-associated" fiber genes are significantly down regulated. Genes (81) significantly up-regulated during secondary cell wall synthesis are involved in cell wall biogenesis and energy/carbohydrate metabolism, which is consistent with the stage of cellulose synthesis during secondary cell wall modification in developing fibers. This work provides the first in-depth view of the genetic complexity of the transcriptome of an expanding cell, and lays the groundwork for studying fundamental biological processes in plant biology with applications in agricultural biotechnology.


Assuntos
Processos de Crescimento Celular/genética , Fibra de Algodão , Genômica/métodos , Gossypium/genética , Parede Celular/metabolismo , Etiquetas de Sequências Expressas , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Gossypium/citologia , Gossypium/crescimento & desenvolvimento , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transcrição Gênica/genética
11.
Science ; 304(5669): 417-20, 2004 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-15087544

RESUMO

Autonomous floats profiling in high-nitrate low-silicate waters of the Southern Ocean observed carbon biomass variability and carbon exported to depths of 100 m during the 2002 Southern Ocean Iron Experiment (SOFeX) to detect the effects of iron fertilization of surface water there. Control and "in-patch" measurements documented a greater than fourfold enhancement of carbon biomass in the iron-amended waters. Carbon export through 100 m increased two- to sixfold as the patch subducted below a front. The molar ratio of iron added to carbon exported ranged between 10(4) and 10(5). The biomass buildup and export were much higher than expected for iron-amended low-silicate waters.


Assuntos
Biomassa , Carbono/análise , Ferro , Fitoplâncton/crescimento & desenvolvimento , Água do Mar , Carbono/metabolismo , Ferro/metabolismo , Oceanos e Mares , Fitoplâncton/metabolismo , Robótica , Água do Mar/química , Temperatura
12.
Science ; 296(5565): 92-100, 2002 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-11935018

RESUMO

The genome of the japonica subspecies of rice, an important cereal and model monocot, was sequenced and assembled by whole-genome shotgun sequencing. The assembled sequence covers 93% of the 420-megabase genome. Gene predictions on the assembled sequence suggest that the genome contains 32,000 to 50,000 genes. Homologs of 98% of the known maize, wheat, and barley proteins are found in rice. Synteny and gene homology between rice and the other cereal genomes are extensive, whereas synteny with Arabidopsis is limited. Assignment of candidate rice orthologs to Arabidopsis genes is possible in many cases. The rice genome sequence provides a foundation for the improvement of cereals, our most important crops.


Assuntos
Genoma de Planta , Oryza/genética , Análise de Sequência de DNA , Arabidopsis/genética , Mapeamento Cromossômico , Cromossomos/genética , Biologia Computacional , Sequência Conservada , DNA de Plantas/genética , Bases de Dados de Ácidos Nucleicos , Grão Comestível/genética , Duplicação Gênica , Genes de Plantas , Genômica , Oryza/metabolismo , Oryza/fisiologia , Proteínas de Transporte de Fosfato/genética , Doenças das Plantas , Proteínas de Plantas/química , Proteínas de Plantas/genética , Estruturas Vegetais/genética , Sequências Repetitivas de Ácido Nucleico , Homologia de Sequência do Ácido Nucleico , Software , Sintenia , Fatores de Transcrição/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...