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1.
PLoS One ; 17(5): e0267737, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35511813

RESUMO

Bull kelp, Nereocystis luetkeana, is an iconic kelp forest species of the Northeast Pacific that provides a wide range of ecosystem services to coastal marine species and society. In northern California, U.S.A., Nereocystis abundance declined sharply in 2014 and has yet to recover. While abiotic and biotic stressors were present prior to 2014, the population collapse highlights the need for a better understanding of how environmental conditions impact Nereocystis. In this study, we used a newly-developed, satellite-based dataset of bull kelp abundance, proxied by canopy cover over 20 years, to test the hypothesis that winter oceanographic conditions determine summer Nereocystis canopy cover. For the years before the collapse (1991 through 2013), wintertime ocean conditions, synthesized in a Multivariate Ocean Climate Indicator (MOCI), were indeed a good predictor of summer Nereocystis canopy cover (R2 = 0.40 to 0.87). We attribute this relationship to the effects of upwelling and/or temperature on nutrient availability. South of Point Arena, California, winter ocean conditions had slightly lower explanatory power than north of Point Arena, also reflective of spring upwelling-driven nutrient entrainment. Results suggest that the Nereocystis gametophytes and/or early sporophytes are sensitive to winter oceanographic conditions. Furthermore, environmental conditions in winter 2014 could have been used to predict the Nereocystis collapse in summer 2014, and for kelp north of Point Arena, a further decline in 2015. Importantly, environmental models do not predict changes in kelp after 2015, suggesting biotic factors suppressed kelp recovery, most likely extreme sea urchin herbivory. Conditions during winter, a season that is often overlooked in studies of biophysical interactions, are useful for predicting summer Nereocystis kelp forest canopy cover, and will be useful in supporting kelp restoration actions in California and perhaps elsewhere in the world.


Assuntos
Kelp , Phaeophyceae , California , Ecossistema , Florestas , Estações do Ano
2.
Sci Adv ; 8(18): eabm3468, 2022 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-35522743

RESUMO

Ocean memory, the persistence of ocean conditions, is a major source of predictability in the climate system beyond weather time scales. We show that ocean memory, as measured by the year-to-year persistence of sea surface temperature anomalies, is projected to steadily decline in the coming decades over much of the globe. This global decline in ocean memory is predominantly driven by shoaling of the upper-ocean mixed layer depth in response to global surface warming, while thermodynamic and dynamic feedbacks can contribute substantially regionally. As the mixed layer depth shoals, stochastic forcing becomes more effective in driving sea surface temperature anomalies, increasing high-frequency noise at the expense of persistent signals. Reduced ocean memory results in shorter lead times of skillful persistence-based predictions of sea surface thermal conditions, which may present previously unknown challenges for predicting climate extremes and managing marine biological resources under climate change.

3.
Plants (Basel) ; 10(12)2021 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-34961248

RESUMO

Silverleaf is an important fungal trunk disease of fruit crops, such as Japanese plum (Prunus salicina). It is known that infection by Chondrostereum purpureum results in discolored wood, "silvered" foliage, and tree decline. However, effects on fruit yield and quality have not been assessed. Therefore, the objectives of this study were to determine C. purpureum pathogenicity on P. salicina and the effects on physiology, fruit yield, and quality, in Chile, in 2019 and 2020. Wood samples from affected plum trees were collected in the Chilean plum productive area. Fungi were isolated by plating wood sections from the necrosis margin on culture media. Morphological and molecular characteristics of the isolates corresponded to C. purpureum (98%). Representative isolates were inoculated from healthy plum plants and after 65-d incubation, wood necrotic lesions and silver leaves were visible. Fungi were reisolated, fulfilling Koch's postulates. To determine Silverleaf effects, xylem water potential and fruit yield and quality were measured in healthy and Silverleaf-diseased plum trees 'Angeleno'. Water potential was altered in diseased trees, and fruit yield was reduced by 51% (2019) and by 41% (2020) compared to fruit from healthy trees. Moreover, cover-colour, equatorial-diameter, and weight were reduced, and fruit were softer, failing to meet the criteria to be properly commercialized and exported to demanding markets.

4.
PLoS Negl Trop Dis ; 15(3): e0009215, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33684128

RESUMO

BACKGROUND: The progressive disseminated histoplasmosis (PDH) has been associated with severe disease and high risk of death among people living with HIV (PLWHIV). Therefore, the purpose of this multicenter, prospective, double-blinded study done in ten Mexican hospitals was to determine the diagnostic accuracy of detecting Histoplasma capsulatum antigen in urine using the IMMY ALPHA Histoplasma EIA kit (IAHE), clarus Histoplasma GM Enzyme Immunoassay (cHGEI IMMY) and MiraVista Histoplasma Urine Antigen LFA (MVHUALFA); as well as the Hcp100 and 1281-1283220SCAR nested PCRs in blood, bone-marrow, tissue biopsies and urine. METHODOLOGY/PRINCIPAL FINDINGS: We included 415 PLWHIV older than 18 years of age with suspicion of PDH. Using as diagnostic standard recovery of H. capsulatum in blood, bone marrow or tissue cultures, or histopathological exam compatible, detected 108 patients (26%, [95%CI, 21.78-30.22]) with proven-PDH. We analyzed 391 urine samples by the IAHE, cHGEI IMMY and MVHUALFA; the sensitivity/specificity values obtained were 67.3% (95% CI, 57.4-76.2) / 96.2% (95% CI, 93.2-98.0) for IAHE, 91.3% (95% CI, 84.2-96.0) / 90.9% (95% CI, 87.0-94.0) for cHGEI IMMY and 90.4% (95% CI, 83.0-95.3) / 92.3% (95% CI, 88.6-95.1) for MVHUALFA. The Hcp100 nested PCR was performed on 393, 343, 75 and 297, blood, bone marrow, tissue and urine samples respectively; the sensitivity/specificity values obtained were 62.9% (95%CI, 53.3-72.5)/ 89.5% (95%CI, 86.0-93.0), 65.9% (95%CI, 56.0-75.8)/ 89.0% (95%CI, 85.2-92.9), 62.1% (95%CI, 44.4-79.7)/ 82.6% (95%CI, 71.7-93.6) and 34.9% (95%CI, 24.8-46.2)/ 67.3% (95%CI, 60.6-73.5) respectively; and 1281-1283220SCAR nested PCR was performed on 392, 344, 75 and 291, respectively; the sensitivity/specificity values obtained were 65.3% (95% CI, 55.9-74.7)/ 58.8% (95%CI, 53.2-64.5), 70.8% (95%CI, 61.3-80.2)/ 52.9% (95%CI, 46.8-59.1), 71.4% (95%CI, 54.7-88.2)/ 40.4% (95%CI, 26.4-54.5) and 18.1% (95%CI, 10.5-28.1)/ 90.4% (95%CI, 85.5-94.0), respectively. CONCLUSIONS/SIGNIFICANCE: The cHGEI IMMY and MVHUALFA tests showed excellent performance for the diagnosis of PDH in PLWHIV. The integration of these tests in clinical laboratories will certainly impact on early diagnosis and treatment.


Assuntos
Antígenos de Fungos/urina , Infecções por HIV/complicações , HIV-1 , Histoplasmose/complicações , Adulto , Feminino , Infecções por HIV/epidemiologia , Histoplasma/imunologia , Histoplasma/metabolismo , Histoplasmose/epidemiologia , Histoplasmose/urina , Humanos , Técnicas Imunoenzimáticas , Masculino , México/epidemiologia , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade , Adulto Jovem
5.
PLoS One ; 16(1): e0244960, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33481844

RESUMO

Spatial structuring of mid-trophic level forage communities in the Gulf of Alaska (GoA) is poorly understood, even though it has clear implications for the health of fisheries and marine wildlife populations. Here, we test the hypothesis that summertime (May-August) mesozooplankton communities are spatially-persistent across years of varying ocean conditions, including during the marine heatwave of 2014-2016. We use spatial ordinations and hierarchical clustering of Continuous Plankton Recorder (CPR) sampling over 17 years (2000-2016) to (1) characterize typical zooplankton communities in different regions of the GoA, and (2) investigate spatial structuring relative to variation in ocean temperatures and circulation. Five regional communities were identified, each representing distinct variation in the abundance of 18 primary zooplankton taxa: a distinct cluster of coastal taxa on the continental shelf north of Vancouver Island; a second cluster in the western GoA associated with strong currents and cold water east of Unimak Pass; a shelf break cluster rich in euphausiids found at both the eastern and western margins of the GoA; a broad offshore cluster of abundant pelagic zooplankton in the southern GoA gyre associated with stable temperature and current conditions; and a final offshore cluster exhibiting low zooplankton abundance concentrated along the northeastern arm of the subarctic gyre where ocean conditions are dominated by eddy activity. When comparing years of anomalous warm and cold sea surface temperatures, we observed change in the spatial structure in coastal communities, but little change (i.e., spatial persistence) in the northwestern GoA basin. Whereas previous studies have shown within-region variability in zooplankton communities in response to ocean climate, we highlight both consistency and change in regional communities, with interannual variability in shelf communities and persistence in community structure offshore. These results suggest greater variability in coastal food webs than in the central portion of the GoA, which may be important to energy exchange from lower to upper trophic levels in the mesoscale biomes of this ecosystem.


Assuntos
Zooplâncton , Alaska , Animais , Ecossistema , Oceano Pacífico , Análise Espaço-Temporal , Zooplâncton/fisiologia
6.
Biomimetics (Basel) ; 5(2)2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32630500

RESUMO

Liver is an essential organ that carries out multiple functions such as glycogen storage, the synthesis of plasma proteins, and the detoxification of xenobiotics. Hepatocytes are the parenchyma that sustain almost all the functions supported by this organ. Hepatocytes and non-parenchymal cells respond to the mechanical alterations that occur in the extracellular matrix (ECM) caused by organogenesis and regenerating processes. Rearrangements of the ECM modify the composition and mechanical properties that result in specific dedifferentiation programs inside the hepatic cells. Quiescent hepatocytes are embedded in the soft ECM, which contains an important concentration of fibrillar collagens in combination with a basement membrane-associated matrix (BM). This work aims to evaluate the role of fibrillar collagens and BM on actin cytoskeleton organization and the function of rat primary hepatocytes cultured on soft elastic polyacrylamide hydrogels (PAA HGs). We used rat tail collagen type I and Matrigel® as references of fibrillar collagens and BM respectively and mixed different percentages of collagen type I in combination with BM. We also used peptides obtained from decellularized liver matrices (dECM). Remarkably, hepatocytes showed a poor adhesion in the absence of collagen on soft PAA HGs. We demonstrated that collagen type I inhibited apoptosis and activated extracellular signal-regulated kinases 1/2 (ERK1/2) in primary hepatocytes cultured on soft hydrogels. Epidermal growth factor (EGF) was not able to rescue cell viability in conjugated BM but affected cell aggregation in soft PAA HGs conjugated with combinations of different proportions of collagen and BM. Interestingly, actin cytoskeleton was localized and preserved close to plasma membrane (cortical actin) and proximal to intercellular ducts (canaliculi-like structures) in soft conditions; however, albumin protein expression was not preserved, even though primary hepatocytes did not remodel their actin cytoskeleton significantly in soft conditions. This investigation highlights the important role of fibrillar collagens on soft hydrogels for the maintenance of survival and aggregation of the hepatocytes. Data suggest evaluating the conditions that allow the establishment of optimal biomimetic environments for physiology and cell biology studies, where the phenotype of primary cells may be preserved for longer periods of time.

8.
Microb Drug Resist ; 26(11): 1372-1382, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32027229

RESUMO

Background: Surveillance of antimicrobial resistance (AMR) requires an international approach with national and local strategies. Our aim was to summarize a retrospective 10-year report of antibiotic resistance of gram-positive and gram-negative bacteria in Mexico. Methods: A total of 46 centers from 22 states of Mexico participated. Databases of AMR from January 2009 to December 2018 were included for most species. The 10-year period was divided into five 2-year periods. Results: For Staphylococcus aureus, a decrease in resistance in all specimens was observed for erythromycin and oxacillin (p < 0.0001 for each). For Enterobacter spp., resistance to meropenem increased for urine specimens (p = 0.0042). For Klebsiella spp., increased drug resistance in specimens collected from blood was observed for trimethoprim/sulfamethoxazole, gentamicin, tobramycin (p < 0.0001 for each), meropenem (p = 0.0014), and aztreonam (p = 0.0030). For Acinetobacter baumannii complex, high drug resistance was detected for almost all antibiotics, including carbapenems, except for tobramycin, which showed decreased resistance for urine, respiratory, and blood isolates (p < 0.0001 for each), and for amikacin, which showed a decrease in resistance in urine specimens (p = 0.0002). An increase in resistance to cefepime was found for urine, respiratory, and blood specimens (p < 0.0001 for each). For Pseudomonas aeruginosa, aztreonam resistance increased for isolates recovered from blood (p = 0.0001). Conclusion: This laboratory-based surveillance of antibiotic resistance shows that resistance is increasing for some antibiotics in different bacterial species in Mexico and highlights the need for continuous monitoring of antibiotic resistance.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/microbiologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , México , Testes de Sensibilidade Microbiana/métodos , Estudos Retrospectivos
9.
PLoS One ; 15(1): e0226087, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31940310

RESUMO

About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California to Alaska. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Three-quarters of murres were found in the Gulf of Alaska and the remainder along the West Coast. Studies show that only a fraction of birds that die at sea typically wash ashore, and we estimate that total mortality approached 1 million birds. About two-thirds of murres killed were adults, a substantial blow to breeding populations. Additionally, 22 complete reproductive failures were observed at multiple colonies region-wide during (2015) and after (2016-2017) the mass mortality event. Die-offs and breeding failures occur sporadically in murres, but the magnitude, duration and spatial extent of this die-off, associated with multi-colony and multi-year reproductive failures, is unprecedented and astonishing. These events co-occurred with the most powerful marine heatwave on record that persisted through 2014-2016 and created an enormous volume of ocean water (the "Blob") from California to Alaska with temperatures that exceeded average by 2-3 standard deviations. Other studies indicate that this prolonged heatwave reduced phytoplankton biomass and restructured zooplankton communities in favor of lower-calorie species, while it simultaneously increased metabolically driven food demands of ectothermic forage fish. In response, forage fish quality and quantity diminished. Similarly, large ectothermic groundfish were thought to have increased their demand for forage fish, resulting in greater top-predator demands for diminished forage fish resources. We hypothesize that these bottom-up and top-down forces created an "ectothermic vise" on forage species leading to their system-wide scarcity and resulting in mass mortality of murres and many other fish, bird and mammal species in the region during 2014-2017.


Assuntos
Charadriiformes/fisiologia , Clima , Temperatura Alta , Mortalidade , Reprodução , Animais , Oceano Pacífico
10.
Arch. latinoam. nutr ; 69(4): 259-273, dic. 2019. tab
Artigo em Espanhol | LIVECS, LILACS, UY-BNMED, BNUY | ID: biblio-1103673

RESUMO

La crisis por COVID-19 (SARS-CoV-2) puede convertirse en una catástrofe alimentaria para Latinoamérica, aumentando las personas que padecen hambre de 135 a 265 millones, especialmente en Venezuela, Guatemala, Honduras, Haití y El Salvador, que ya enfrentaban crisis económicas y sanitarias. Este manuscrito presenta la posición de un grupo de expertos latinoamericanos sobre las recomendaciones de consumo y/o suplementación con vitamina A, C, D, zinc, hierro, folatos y micronutrientes múltiples, en contextos de desnutrición, para grupos vulnerables: mujeres embarazadas y lactantes, niñas y niños menores de 5 años y adultos mayores. Las recomendaciones buscan disminuir el impacto potencial que tendrá COVID-19 en el estado nutricional, durante la pandemia. La posición surge de la discusión de dichos expertos con base a la revisión de evidencia científica actual para estos grupos vulnerables. Está dirigida a tomadores de decisiones, encargados de políticas públicas, personal de salud y organismos de la sociedad civil. Después de la lactancia materna y una dieta suficiente en cantidad y calidad, la suplementación con los micronutrientes presentados, puede contribuir a prevenir y tratar enfermedades virales, reforzar el sistema inmune y reducir complicaciones. La lactancia materna con medidas de higiene respiratoria, el suministro de múltiples micronutrientes en polvo para niños desde los 6 meses hasta los 5 años y el aporte de hierro y folatos o micronutrientes múltiples para la embarazada, son estrategias comprobadas y eficaces que deben seguirse implementando en tiempos de COVID-19. Para los adultos mayores la suplementación con vitamina C, D y zinc puede estar indicada(AU)


The COVID-19 crisis (SARS-CoV-2) might transform into a food catastrophe in Latin America and would increase the number of people suffering from hunger from 135 to 265 million, particularly in Venezuela, Guatemala, Honduras, Haiti and El Salvador, already facing economic and health crises. This manuscript presents the position of a group of Latin American experts in nutrition for establishing the recommendations for consumption and / or supplementation with vitamin A, C, D, zinc, iron, folates and multiple micronutrients, in undernutrition contexts, for vulnerable population of pregnant and lactating women, children under 5 years and the elderly. The recommendations seek to decrease the potential impact that COVID-19 will have on nutritional status during the pandemic. The position arises from the discussion of the experts based on the review of current scientific evidence for these vulnerable groups. It aims to reach stakeholders, public policy makers, health personnel and civil society organizations. Only after breastfeeding and a sufficient diet in terms of quantity and quality, a supplementation with the micronutrients mentioned above can help prevent and treat viral diseases, strengthen the immune system and even reduce complications. Breastfeeding with respiratory hygiene measures, the provision of multiple micronutrients powders for children from 6 moths to 5 years of age and the supply of iron and folates or multiple micronutrients tablets for pregnant women are proven and effective strategies that must continue to be implemented during COVID-19 pandemic. For older adults, supplementation with vitamin C, D and zinc might be indicated(AU)


Assuntos
Humanos , Masculino , Feminino , Gravidez , Recém-Nascido , Lactente , Pré-Escolar , Criança , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Infecções Respiratórias , Nutrição dos Grupos Vulneráveis , Fome , Micronutrientes , COVID-19/epidemiologia , Sistema Imunitário , Deficiência de Vitaminas , Suplementos Nutricionais , Deficiências Nutricionais , Desnutrição , Pandemias , América Latina
11.
Sci Rep ; 9(1): 4216, 2019 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-30862867

RESUMO

During 2014-2016, severe marine heatwaves in the northeast Pacific triggered well-documented disturbances including mass mortalities, harmful algal blooms, and declines in subtidal kelp beds. However, less attention has been directed towards understanding how changes in sea surface temperature (SST) and alongshore currents during this period influenced the geographic distribution of coastal taxa. Here, we examine these effects in northern California, USA, with a focus on the region between Point Reyes and Point Arena. This region represents an important biogeographic transition zone that lies <150 km north of Monterey Bay, California, where numerous southern species have historically reached their northern (poleward) range limits. We report substantial changes in geographic distributions and/or abundances across a diverse suite of 67 southern species, including an unprecedented number of poleward range extensions (37) and striking increases in the recruitment of owl limpets (Lottia gigantea) and volcano barnacles (Tetraclita rubescens). These ecological responses likely arose through the combined effects of extreme SST, periods of anomalous poleward flow, and the unusually long duration of heatwave events. Prolonged marine heatwaves and enhanced poleward dispersal may play an important role in longer-term shifts in the composition of coastal communities in northern California and other biogeographic transition zones.


Assuntos
Baías , Biota/fisiologia , Crustáceos/fisiologia , Gastrópodes/fisiologia , Animais , California
12.
PLoS Negl Trop Dis ; 12(11): e0006872, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30395572

RESUMO

BACKGROUND: The Histoplasma urine antigen (HUAg) is the preferred method to diagnose progressive disseminated histoplasmosis (PDH) in HIV patients. In 2007, IMMY ALPHA Histoplasma EIA was approved for clinical for on-site use, and therefore useful for regions outside the United States. However, ALPHA-HUAg is considered inferior to the MVista-HUAg which is only available on referral. We aim to evaluate the diagnostic accuracy of ALPHA-HUAg. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a multicenter, prospective, diagnostic test study in two secondary and eight tertiary-care facilities in Mexico. We included HIV patient with PDH suspicion and evaluated ALPHA-HUAg diagnostic accuracy using as reference standard the Histoplasma capsulatum growth on blood, bone marrow, and tissue cultures or compatible histopathologic exam (PDH-proven). We evaluated the results of 288 patients, 29.5% (85/288; 95% confidence interval [CI], 24.3-35.1) had PDH. The sensitivity of ALPHA-HUAg was 67.1% (95% CI, 56-76.8%) and the specificity was 97.5% (95% CI, 94.3%-99.1%). The positive likelihood ratio was 27.2 (95% CI; 11.6-74.4). In 10.5% of the PDH-proven patients, a co-existing opportunistic infection was diagnosed, mostly disseminated Mycobacterium avium complex infection. CONCLUSIONS/SIGNIFICANCE: We observed a high specificity but low sensitivity of IMMY-HUAg. The test may be useful to start early antifungals, but a culture-based approach is necessary since co-infections are frequent and a negative IMMY-HUAg result does not rule out PDH.


Assuntos
Testes Diagnósticos de Rotina/métodos , Infecções por HIV/complicações , Histoplasmose/diagnóstico , Adulto , Antígenos de Fungos , Feminino , Histoplasma , Histoplasmose/etiologia , Humanos , Masculino , México , Estudos Prospectivos
13.
Food Res Int ; 114: 90-96, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30361031

RESUMO

The Bromeliaceae Puya chilensis Mol. is a native monocotyledonous food plant that can be found in central Chile. It is traditionally known as chagual. The tender basal part of the leaves, just starting from the meristem, are consumed as a salad. The aim of this work was to describe the phenolic content and composition of the meristem and leaves of chagual, as well as their antioxidant capacity and inhibitory activity against metabolic syndrome-associated enzymes. Samples of chagual, including two cultivated and three wild growing plants, were analyzed and compared for composition and bioactivity. From the phenolic enriched extract of the plant (PEE), 26 compounds were tentatively identified by HPLC-DAD-ESI-MSn, including 12 hydroxycinnamic acids and 14 flavonoids. The main compounds were identified as diferuloyl hexaric acid isomers and 5-p-Coumaroylquinic acid. The compounds were quantified in both meristem and leaves. The PEE content was up to ten times higher in the meristem than in the leaves, ranging from 0.18 to 124.08 mg/g PEE. The samples inhibited α-glucosidase, but did not show effect on α-amylase and pancreatic lipase. This is the first report on the polyphenol composition and bioactivity of the edible components of the chagual food plant.


Assuntos
Antioxidantes/análise , Bromeliaceae/química , Meristema/química , Extratos Vegetais/química , Folhas de Planta/química , Polifenóis/análise , Antioxidantes/farmacologia , Compostos de Bifenilo , Chile , Ácidos Cumáricos/análise , Flavonoides/análise , Inibidores de Glicosídeo Hidrolases/análise , Inibidores de Glicosídeo Hidrolases/farmacologia , Picratos , Extratos Vegetais/farmacologia , Ácido Quínico/análise , alfa-Glucosidases/efeitos dos fármacos
14.
Glob Chang Biol ; 24(6): 2305-2314, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29575413

RESUMO

Along the western margin of North America, the winter expression of the North Pacific High (NPH) strongly influences interannual variability in coastal upwelling, storm track position, precipitation, and river discharge. Coherence among these factors induces covariance among physical and biological processes across adjacent marine and terrestrial ecosystems. Here, we show that over the past century the degree and spatial extent of this covariance (synchrony) has substantially increased, and is coincident with rising variance in the winter NPH. Furthermore, centuries-long blue oak (Quercus douglasii) growth chronologies sensitive to the winter NPH provide robust evidence that modern levels of synchrony are among the highest observed in the context of the last 250 years. These trends may ultimately be linked to changing impacts of the El Niño Southern Oscillation on midlatitude ecosystems of North America. Such a rise in synchrony may destabilize ecosystems, expose populations to higher risks of extinction, and is thus a concern given the broad biological relevance of winter climate to biological systems.


Assuntos
Mudança Climática , Ecossistema , El Niño Oscilação Sul , Monitoramento Ambiental , Rios , Estações do Ano , Estados Unidos
15.
Science ; 345(6203): 1498-502, 2014 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-25237100

RESUMO

Reported trends in the mean and variability of coastal upwelling in eastern boundary currents have raised concerns about the future of these highly productive and biodiverse marine ecosystems. However, the instrumental records on which these estimates are based are insufficiently long to determine whether such trends exceed preindustrial limits. In the California Current, a 576-year reconstruction of climate variables associated with winter upwelling indicates that variability increased over the latter 20th century to levels equaled only twice during the past 600 years. This modern trend in variance may be unique, because it appears to be driven by an unprecedented succession of extreme, downwelling-favorable, winter climate conditions that profoundly reduce productivity for marine predators of commercial and conservation interest.


Assuntos
Organismos Aquáticos , Ecossistema , Oceanos e Mares , Animais , Biodiversidade , Mudança Climática , Cadeia Alimentar , Estações do Ano
16.
J Nanosci Nanotechnol ; 13(8): 5680-6, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23882817

RESUMO

We apply functionalized carbon nanoshell and carbon sphere based composites in poly(vinylphenol) matrix in write-once-read-many-times memory elements. The devices based on carbon nanoshells show an ON/OFF current ratio of 10(5) and long-term information retention. The functionalized carbon nanoshells and carbon spheres show improved dispersion in the poly(vinylphenol) matrix, allowing the preparation of homogeneous films even at the submicrometer scale. The low ON current allows low power operation, dissipating less than 10(-4) J per square meter device active area during the write operation, which is the most energy consuming one.

17.
J Nanosci Nanotechnol ; 8(12): 6470-3, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19205224

RESUMO

Using nonlinear absorption at 532 nm in the nanosecond temporal regime, we have measured the low fluence nonlinear transmittance properties of the reverse saturable absorbing carbocyanine dye, 1,1',3,3,3',3'-hexamethylindotricarbocyanine iodide (HITCI), blended with well dispersed carbon nanotubes. The nonlinear optical properties of the blends are strongly dependent on the ratio of dye to nanotubes in solution. In the case where the nanotubes per dye molecule ratio is large, we see a distinctive enhancement in optical fluence limiting properties of the system, suggesting enhanced absorption of the excited states. However, when the nanotube to dye ratio decreases, the system's response is dominated by the behavior of the dye. We suggest that this can be understood as a two component system in which sensitized dye molecules associated with the nanotubes have an effectively different optical cross-section from the dye molecules far from the nanotubes. From classical antennae considerations, this is expected.

18.
Org Lett ; 7(26): 5749-52, 2005 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-16354057

RESUMO

[reaction: see text] Formation of a controlled fullerene mesophase within an organic host system has enabled us to create high-power conversion efficiency photovoltaics. This mesophase is formed using thermal gradients that provide a fluidic mobility of the fullerenes allowing for greater dispersion of nanocrystalline 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C61 (PCBM) within regioregular poly(3-hexylthiophene) (P3HT). From this reorganization of the component materials in the matrix the overall efficiency of the system jumps dramatically from the roughly 2.4% to 5.2%.

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