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1.
Nature ; 554(7692): 351-355, 2018 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-29400700

RESUMO

The presence of large Northern Hemisphere ice sheets and reduced greenhouse gas concentrations during the Last Glacial Maximum fundamentally altered global ocean-atmosphere climate dynamics. Model simulations and palaeoclimate records suggest that glacial boundary conditions affected the El Niño-Southern Oscillation, a dominant source of short-term global climate variability. Yet little is known about changes in short-term climate variability at mid- to high latitudes. Here we use a high-resolution water isotope record from West Antarctica to demonstrate that interannual to decadal climate variability at high southern latitudes was almost twice as large at the Last Glacial Maximum as during the ensuing Holocene epoch (the past 11,700 years). Climate model simulations indicate that this increased variability reflects an increase in the teleconnection strength between the tropical Pacific and West Antarctica, owing to a shift in the mean location of tropical convection. This shift, in turn, can be attributed to the influence of topography and albedo of the North American ice sheets on atmospheric circulation. As the planet deglaciated, the largest and most abrupt decline in teleconnection strength occurred between approximately 16,000 years and 15,000 years ago, followed by a slower decline into the early Holocene.

2.
Ecol Appl ; 30(3): e02070, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31903628

RESUMO

Marine protected areas (MPAs) are increasingly implemented as a conservation tool worldwide. In many cases, they are managed adaptively: the abundance of target species is monitored, and observations are compared to some model-based expectation for the trajectory of population recovery to ensure that the MPA is achieving its goals. Most previous analyses of the transient (short-term) response of populations to the cessation of fishing inside MPAs have dealt only with gonochore (fixed-sex) species. However, many important fishery species are protogynous hermaphrodites (female-to-male sex-changing). Because size-selective harvest will predominantly target males in these species, harvesting not only reduces abundance but also skews the sex ratio toward females. Thus the response to MPA implementation will involve changes in both survival and sex ratio, and ultimately reproductive output. We used an age-structured model of a generic sex-changing fish population to compare transient population dynamics after MPA implementation to those of an otherwise similar gonochore population and examine how different features of sex-changing life history affect those dynamics. We examined both demographically open (most larval recruitment comes from outside the MPA) and demographically closed (most larval recruitment is locally produced) dynamics. Under both scenarios, population recovery of protogynous species takes longer when fishing was more intense pre-MPA (as in gonochores), but also depends heavily on the mating function, the degree to which the sex ratio affects reproduction. If few males are needed and reproduction is not affected by a highly female-biased sex ratio, then population recovery is much faster; if males are a limiting resource, then increases in abundance after MPA implementation are much slower than for gonochores. Unfortunately, the mating function is largely unknown for fishes. In general, we expect that most protogynous species with haremic mating systems will be in the first category (few males needed), though there is at least one example of a fish species (though not a sex-changing species) for which males are limiting. Thus a better understanding of the importance of male fish to population dynamics is needed for the adaptive management of MPAs.


Assuntos
Conservação dos Recursos Naturais , Pesqueiros , Animais , Feminino , Peixes , Masculino , Dinâmica Populacional , Reprodução
3.
Nature ; 488(7409): 70-2, 2012 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-22859203

RESUMO

One of the greatest sources of uncertainty for future climate predictions is the response of the global carbon cycle to climate change. Although approximately one-half of total CO(2) emissions is at present taken up by combined land and ocean carbon reservoirs, models predict a decline in future carbon uptake by these reservoirs, resulting in a positive carbon-climate feedback. Several recent studies suggest that rates of carbon uptake by the land and ocean have remained constant or declined in recent decades. Other work, however, has called into question the reported decline. Here we use global-scale atmospheric CO(2) measurements, CO(2) emission inventories and their full range of uncertainties to calculate changes in global CO(2) sources and sinks during the past 50 years. Our mass balance analysis shows that net global carbon uptake has increased significantly by about 0.05 billion tonnes of carbon per year and that global carbon uptake doubled, from 2.4 ± 0.8 to 5.0 ± 0.9 billion tonnes per year, between 1960 and 2010. Therefore, it is very unlikely that both land and ocean carbon sinks have decreased on a global scale. Since 1959, approximately 350 billion tonnes of carbon have been emitted by humans to the atmosphere, of which about 55 per cent has moved into the land and oceans. Thus, identifying the mechanisms and locations responsible for increasing global carbon uptake remains a critical challenge in constraining the modern global carbon budget and predicting future carbon-climate interactions.


Assuntos
Atmosfera/química , Dióxido de Carbono/análise , Sequestro de Carbono , Mudança Climática/estatística & dados numéricos , Água do Mar/química , Carbono/análise , Dióxido de Carbono/história , História do Século XX , História do Século XXI , Atividades Humanas , Modelos Teóricos , Oceanos e Mares , Fatores de Tempo , Incerteza
4.
Syst Rev ; 13(1): 61, 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38331893

RESUMO

BACKGROUND: Objective measures of screen time are necessary to better understand the complex relationship between screen time and health outcomes. However, current objective measures of screen time (e.g., passive sensing applications) are limited in identifying the user of the mobile device, a critical limitation in children's screen time research where devices are often shared across a family. Behavioral biometrics, a technology that uses embedded sensors on modern mobile devices to continuously authenticate users, could be used to address this limitation. OBJECTIVE: The purpose of this scoping review was to summarize the current state of behavioral biometric authentication and synthesize these findings within the scope of applying behavioral biometric technology to screen time measurement. METHODS: We systematically searched five databases (Web of Science Core Collection, Inspec in Engineering Village, Applied Science & Technology Source, IEEE Xplore, PubMed), with the last search in September of 2022. Eligible studies were on the authentication of the user or the detection of demographic characteristics (age, gender) using built-in sensors on mobile devices (e.g., smartphone, tablet). Studies were required to use the following methods for authentication: motion behavior, touch, keystroke dynamics, and/or behavior profiling. We extracted study characteristics (sample size, age, gender), data collection methods, data stream, model evaluation metrics, and performance of models, and additionally performed a study quality assessment. Summary characteristics were tabulated and compiled in Excel. We synthesized the extracted information using a narrative approach. RESULTS: Of the 14,179 articles screened, 122 were included in this scoping review. Of the 122 included studies, the most highly used biometric methods were touch gestures (n = 76) and movement (n = 63), with 30 studies using keystroke dynamics and 6 studies using behavior profiling. Of the studies that reported age (47), most were performed exclusively in adult populations (n = 34). The overall study quality was low, with an average score of 5.5/14. CONCLUSION: The field of behavioral biometrics is limited by the low overall quality of studies. Behavioral biometric technology has the potential to be used in a public health context to address the limitations of current measures of screen time; however, more rigorous research must be performed in child populations first. SYSTEMATIC REVIEW REGISTRATION: The protocol has been pre-registered in the Open Science Framework database ( https://doi.org/10.17605/OSF.IO/92YCT ).


Assuntos
Identificação Biométrica , Humanos , Identificação Biométrica/métodos , Tempo de Tela , Biometria/métodos , Smartphone , Criança , Demografia
6.
J Environ Qual ; 42(4): 1274-80, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24216379

RESUMO

Difficulties in accessing high-quality data on trace gas fluxes and performance of bioenergy/bioproduct feedstocks limit the ability of researchers and others to address environmental impacts of agriculture and the potential to produce feedstocks. To address those needs, the GRACEnet (Greenhouse gas Reduction through Agricultural Carbon Enhancement network) and REAP (Renewable Energy Assessment Project) research programs were initiated by the USDA Agricultural Research Service (ARS). A major product of these programs is the creation of a database with greenhouse gas fluxes, soil carbon stocks, biomass yield, nutrient, and energy characteristics, and input data for modeling cropped and grazed systems. The data include site descriptors (e.g., weather, soil class, spatial attributes), experimental design (e.g., factors manipulated, measurements performed, plot layouts), management information (e.g., planting and harvesting schedules, fertilizer types and amounts, biomass harvested, grazing intensity), and measurements (e.g., soil C and N stocks, plant biomass amount and chemical composition). To promote standardization of data and ensure that experiments were fully described, sampling protocols and a spreadsheet-based data-entry template were developed. Data were first uploaded to a temporary database for checking and then were uploaded to the central database. A Web-accessible application allows for registered users to query and download data including measurement protocols. Separate portals have been provided for each project (GRACEnet and REAP) at nrrc.ars.usda.gov/slgracenet/#/Home and nrrc.ars.usda.gov/slreap/#/Home. The database architecture and data entry template have proven flexible and robust for describing a wide range of field experiments and thus appear suitable for other natural resource research projects.


Assuntos
Efeito Estufa , Solo , Agricultura , Carbono , Produtos Agrícolas , Fertilizantes , Solo/química
7.
Nat Commun ; 12(1): 2106, 2021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33833238

RESUMO

Data availability and temporal resolution make it challenging to unravel the anatomy (duration and temporal phasing) of the Last Glacial abrupt climate changes. Here, we address these limitations by investigating the anatomy of abrupt changes using sub-decadal-scale records from Greenland ice cores. We highlight the absence of a systematic pattern in the anatomy of abrupt changes as recorded in different ice parameters. This diversity in the sequence of changes seen in ice-core data is also observed in climate parameters derived from numerical simulations which exhibit self-sustained abrupt variability arising from internal atmosphere-ice-ocean interactions. Our analysis of two ice cores shows that the diversity of abrupt warming transitions represents variability inherent to the climate system and not archive-specific noise. Our results hint that during these abrupt events, it may not be possible to infer statistically-robust leads and lags between the different components of the climate system because of their tight coupling.

8.
Langmuir ; 26(24): 18985-91, 2010 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-21090753

RESUMO

X-ray reflectivity from an air-buffer interfacial ß-casein monomolecular film placed on a solution of chymosin (renin) showed unexpectedly slow proteolytic cleavage. To understand this, the separate structures of ß-casein and chymosin, the presentation of each molecule to the other at the air/liquid interface, and that of their mixtures is reported. At the air/solution interface, the hydrophobicity of the protein molecules causes orientation and some deformation of the conformation. When ß-casein was presented to a chymosin monomolecular interfacial film, the chymosin was largely displaced from the surface, which was accounted for by the different surfactancy of the two molecules at 25 °C. There was no observable proteolysis. In the reverse experiment, a significant enzymatic degradation and the signature of hydrophobic fragments was observed but only at and above an enzyme concentration of 0.015 mg/mL in the substrate. For comparison, the air/solution interface of premixed ß-casein with chymosin in phosphate buffer showed that the film was composed of ß-casein proteolytic fragments and chymosin.


Assuntos
Ar , Caseínas/química , Caseínas/metabolismo , Quimosina/metabolismo , Água/química , Adsorção , Animais , Bovinos , Quimosina/química
9.
Nature ; 431(7005): 147-51, 2004 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-15356621

RESUMO

Two deep ice cores from central Greenland, drilled in the 1990s, have played a key role in climate reconstructions of the Northern Hemisphere, but the oldest sections of the cores were disturbed in chronology owing to ice folding near the bedrock. Here we present an undisturbed climate record from a North Greenland ice core, which extends back to 123,000 years before the present, within the last interglacial period. The oxygen isotopes in the ice imply that climate was stable during the last interglacial period, with temperatures 5 degrees C warmer than today. We find unexpectedly large temperature differences between our new record from northern Greenland and the undisturbed sections of the cores from central Greenland, suggesting that the extent of ice in the Northern Hemisphere modulated the latitudinal temperature gradients in Greenland. This record shows a slow decline in temperatures that marked the initiation of the last glacial period. Our record reveals a hitherto unrecognized warm period initiated by an abrupt climate warming about 115,000 years ago, before glacial conditions were fully developed. This event does not appear to have an immediate Antarctic counterpart, suggesting that the climate see-saw between the hemispheres (which dominated the last glacial period) was not operating at this time.

10.
Science ; 197(4306): 891-2, 1977 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-17730173

RESUMO

The variability of the carbon-13/carbon-12 ratio in honeys was evaluated preliminary to use of the ratio to detect the addition of high-fructose corn syrup to honey. Eighty-four honey samples representing 34 states and including 37 floral types from 17 plant families were analyzed. The mean value of the per mil increment in carbon-13 (delta13C) for all samples is -25.2 per mil, and the coefficient of variation is 3.7 percent. This is the smallest variation yet encountered for a honey constituent or physical property. The range and magnitude of the values suggest that the floral sources are C(3) plants.

11.
Science ; 269(5227): 1098-102, 1995 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-17755534

RESUMO

Measurements of the concentrations and carbon-13/carbon-12 isotope ratios of atmospheric carbon dioxide can be used to quantify the net removal of carbon dioxide from the atmosphere by the oceans and terrestrial plants. A study of weekly samples from a global network of 43 sites defined the latitudinal and temporal patterns of the two carbon sinks. A strong terrestrial biospheric sink was found in the temperate latitudes of the Northern Hemisphere in 1992 and 1993, the magnitude of which is roughly half that of the global fossil fuel burning emissions for those years. The challenge now is to identify those processes that would cause the terrestrial biosphere to absorb carbon dioxide in such large quantities.

12.
Science ; 287(5462): 2467-70, 2000 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-10741962

RESUMO

Recent time-series measurements of atmospheric O2 show that the land biosphere and world oceans annually sequestered 1.4 +/- 0.8 and 2.0 +/- 0.6 gigatons of carbon, respectively, between mid-1991 and mid-1997. The rapid storage of carbon by the land biosphere from 1991 to 1997 contrasts with the 1980s, when the land biosphere was approximately neutral. Comparison with measurements of delta13CO2 implies an isotopic flux of 89 +/- 21 gigatons of carbon per mil per year, in agreement with model- and inventory-based estimates of this flux. Both the delta13C and the O2 data show significant interannual variability in carbon storage over the period of record. The general agreement of the independent estimates from O2 and delta13C is a robust signal of variable carbon uptake by both the land biosphere and the oceans.


Assuntos
Atmosfera , Carbono/análise , Carbono/metabolismo , Ecossistema , Oxigênio/análise , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Isótopos de Carbono , Nitrogênio/análise , Oceanos e Mares , Consumo de Oxigênio , Fotossíntese
13.
Coral Reefs ; 28(2): 327-337, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22833699

RESUMO

Design and decision-making for marine protected areas (MPAs) on coral reefs require prediction of MPA effects with population models. Modeling of MPAs has shown how the persistence of metapopulations in systems of MPAs depends on the size and spacing of MPAs, and levels of fishing outside the MPAs. However, the pattern of demographic connectivity produced by larval dispersal is a key uncertainty in those modeling studies. The information required to assess population persistence is a dispersal matrix containing the fraction of larvae traveling to each location from each location, not just the current number of larvae exchanged among locations. Recent metapopulation modeling research with hypothetical dispersal matrices has shown how the spatial scale of dispersal, degree of advection versus diffusion, total larval output, and temporal and spatial variability in dispersal influence population persistence. Recent empirical studies using population genetics, parentage analysis, and geochemical and artificial marks in calcified structures have improved the understanding of dispersal. However, many such studies report current self-recruitment (locally produced settlement/settlement from elsewhere), which is not as directly useful as local retention (locally produced settlement/total locally released), which is a component of the dispersal matrix. Modeling of biophysical circulation with larval particle tracking can provide the required elements of dispersal matrices and assess their sensitivity to flows and larval behavior, but it requires more assumptions than direct empirical methods. To make rapid progress in understanding the scales and patterns of connectivity, greater communication between empiricists and population modelers will be needed. Empiricists need to focus more on identifying the characteristics of the dispersal matrix, while population modelers need to track and assimilate evolving empirical results.

14.
Biochim Biophys Acta ; 1009(3): 287-9, 1989 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-2480812

RESUMO

One LINE 1 repeat has been located 661 bp downstream from the last albumin exon and another approx. 10 kbp downstream from the last alpha-fetoprotein exon in the rat genomic DNA. The LINE 1 repeat following the albumin gene is truncated at its 5' end and is 1204 nucleotides long. The 5' end of the longer repeat downstream from the alpha-fetoprotein gene has not been determined. The two repeats have 95% homology with each other, with the exception of a short diverse 3' end sequence just preceding the putative polyadenylation signal.


Assuntos
Albuminas/genética , Sequências Repetitivas de Ácido Nucleico , alfa-Fetoproteínas/genética , Animais , DNA Viral/genética , Biblioteca Genômica , Dados de Sequência Molecular , Plasmídeos , Ratos , Homologia de Sequência do Ácido Nucleico
15.
Mol Endocrinol ; 2(3): 209-16, 1988 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2899837

RESUMO

A bovine pancreatic preprosomatostatin cDNA clone has been isolated and sequenced. Although it encodes a predicted 116 amino acid preprosomatostatin that is very similar in primary structure to those deduced from other mammalian preprosomatostatin cDNAs, there are some differences in amino acid composition. Hybridization of this clone to Northern blots of fetal bovine pancreatic poly(A+) RNA reveals a mRNA of 700 nucleotides. Evolution of the preprosomatostatin genes was studied by statistical analysis of anglerfish, catfish, bovine, rat, and human cDNA sequences. The results suggest that the two somatostatin genes present in both anglerfish and catfish were the result of a gene duplication event in a common ancestor of anglerfish and catfish.


Assuntos
Evolução Biológica , Somatostatina/genética , Animais , Sequência de Bases , Bovinos , Clonagem Molecular , Dados de Sequência Molecular , Filogenia
16.
Mol Endocrinol ; 1(4): 327-31, 1987 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-2456452

RESUMO

A cDNA library was prepared from poly(A+) RNA isolated from fetal bovine pancreas. Bacterial colonies were screened for sequences homologous to a rat preproinsulin I cDNA probe. Ten positive clones were selected at random and further studied. Northern blot analyses revealed that seven of these clones hybridized to a single RNA species, of approximately 400 nucleotides. Sequence analysis of one of these clones (pbI2885) revealed the entire structural region of bovine preproinsulin mRNA including a 72 nucleotide region encoding a signal peptide enriched in hydrophobic residues. The overall nucleotide homology between bovine and human preproinsulin mRNA was 76% for the preregion, 89% for the A chain, 83% for the B chain, and 68% for the C peptide (including a 15 nucleotide deletion).


Assuntos
Clonagem Molecular , DNA/genética , Proinsulina/genética , Precursores de Proteínas/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Bovinos , Feto , Insulina , Ilhotas Pancreáticas/metabolismo , Dados de Sequência Molecular , Poli A/genética , Poli A/isolamento & purificação , RNA/genética , RNA/isolamento & purificação , RNA Mensageiro
17.
Int J Clin Pract Suppl ; (147): 121-4, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15875648

RESUMO

Aeromonas hydrophila is a rare human pathogen, and worldwide, soft tissue infections following water-related injuries are the most common. However, septic arthritis due to A. hydrophila remains uncommon with only seven cases previously reported in the English literature. In this report, we describe the important clinical features, microbiological findings and management of severe septic arthritis of the knee due to A. hydrophila in a healthy 13-year-old girl following an injury sustained in a private fresh water lake. A review of seven previously reported cases of septic arthritis due to A. hydrophila and the present case suggests that the infection commonly affected the knee and the meta-/intercarpal-phalangeal joint and was frequently rapidly progressive following trauma in fresh water and or associated with leukaemia. Second and third generation cephalosporins, gentamicin, trimethoprim, ciprofloxacin and appropriate orthopaedic management should be promptly instituted. After chemical treatment and chlorination, fresh water becomes free of coliforms, but A. hydrophila persists more compared with the other strains of aeromonas, namely A. sobria and A. caviae. Seawater injuries, unlike freshwater injuries, are not usually associated with aeromonas infections. Further workup on the mechanisms of A. hydrophila resistance to chlorination could probably yield useful information in achieving new procedures of preventing and controlling such infections in public and private fresh water recreational facilities.


Assuntos
Aeromonas hydrophila , Artrite Infecciosa/etiologia , Infecções por Bactérias Gram-Negativas/etiologia , Traumatismos do Joelho/complicações , Adolescente , Feminino , Água Doce/microbiologia , Humanos , Infecção dos Ferimentos/complicações
18.
Gene ; 84(2): 521-2, 1989 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-2612919

RESUMO

The nucleotide sequence of the human placental lactogen-encoding gene enhancer was determined. This tissue-specific enhancer is contained in a region flanked by a 284-bp Alu repeat.


Assuntos
Elementos Facilitadores Genéticos , Lactogênio Placentário/genética , Sequência de Bases , Humanos , Dados de Sequência Molecular
19.
Am J Clin Nutr ; 62(1 Suppl): 242S-247S; discussion 247S-249S, 1995 07.
Artigo em Inglês | MEDLINE | ID: mdl-7598081

RESUMO

Sugar is one of the major dietary components and any relation between sugar and behavior is of major interest. We review the scientific evidence supporting or refuting the relation between sugar and behavior or cognitive function. Little evidence supports the claim that refined sugar intake significantly influences behavior or cognitive performance in children. A few children may have idiosyncratic reactions or rare allergic syndromes and may therefore respond adversely, but this has yet to be substantiated by carefully controlled research. A role for glucose in the potentiation of memory processing appears clear. Further research is required to define the clinical relevance of this role and to elucidate the mechanisms involved. Sucrose may have a sedative effect, at least in infants, but there are no substantial data suggesting that any sugar has analgesic properties.


Assuntos
Comportamento/fisiologia , Cognição/fisiologia , Carboidratos da Dieta/farmacologia , Memória/fisiologia , Carboidratos da Dieta/metabolismo , Glucose/fisiologia , Humanos
20.
Am J Med ; 70(4): 971-5, 1981 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-7211933

RESUMO

The main objective of the Study on the Efficacy of Nosocomial Infection Control (SENIC Project) is to determine whether infection surveillance and control programs have reduced the rates of nosocomial infection in United States hospitals. To study this question, we stratified all hospitals in the SENIC target population into 16 design strata defined by categories of a surveillance and a control index derived from hospitals' responses to a preliminary screening questionnaire, and estimated the nosocomial infection rates among 339,044 randomly selected patients admitted in 1970 and 1975 through 1976 to 338 hospitals selected randomly from the 16 design strata. Finding that the over-all infection rates, standardized for important confounding variables or covariates, in hospitals with higher intensity programs had increased less from 1970 to 1975-1976 than those of hospitals with low intensity programs would indicate the efficacy of these programs. Potentially important confounding variables and covariates being studied include individual patient risk factors, hospital characteristics and the completeness of hospitals' medical records. Since only the first has been explored sufficiently, no conclusions on efficacy can yet be drawn. The analytic techniques were illustrated with preliminary data on infection rates at the four individual sites of infection.


Assuntos
Infecção Hospitalar/prevenção & controle , Vigilância da População , Infecção Hospitalar/epidemiologia , Estudos de Avaliação como Assunto , Humanos , Estudos de Amostragem , Estados Unidos
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