Conteúdo iônico em um testemunho de firn do Platô Antártico

Este trabalho investiga o conteúdo iônico dos 28,73 m superiores do testemunho BR-IC-2 (88°01'21,3"S; 82°04'21,7"W), coletado durante a travessia antártica chileno-brasileira no verão austral de 2004/05. As concentrações dos íons majoritários Na+, K+, Mg2+, Ca2+, Cl-, NO3- e SO42- e do ácido orgânico H3CSO3- (metanosulfonato - MS-) foram determinadas por cromatografia iônica. A datação, baseada na correlação entre as concentrações de Na+ e nssSO42- (sulfato não proveniente de sal marinho), na razão isotópica δD e na identificação de sinais de erupções vulcânicas (Pinatubo / Cerro Hudson em 1993, Agung em 1965 e possivelmente Bristol Island em 1936) constatou uma idade de 85 anos (período 1918–2003) para o testemunho, com precisão de ± 3 anos. A partir da datação foi possível estabelecer a precipitação anual média nesse sítio: 0,15 m eq H2O. Constatou-se uma contribuição de aerossóis de sais marinhos pouco expressiva e uma grande contribuição crustal e biogênica, indicada pelas concentrações de nssCa2+ e nssSO42, respectivamente. O alto valor da razão Cl-/Na+ (4,96) indica que outros fatores, além da contribuição de sal marinho, contribuem para as concentrações desses íons, como a entrada ou formação de HCl e a menor depleção do Cl-. As concentrações de K+ e Mg2+, apesar de apresentarem correlação fraca com os outros íons, são de origem marinha. O MS- mostra valores pouco expressivos para a região e o NO3- não tem correlação com os outros íons, devido à complexidade das fontes, já que este íon se apresenta como um aerossol secundário

Prefacing unexplored archives from Central Andean surface-to-bedrock ice cores through a multifaceted investigation of regional firn and ice core glaciochemistry.

Shallow firn cores, in addition to a near-basal ice core, were recovered in 2018 from the Quelccaya ice cap (5470 m a.s.l) in the Cordillera Vilcanota, Peru, and in 2017 from the Nevado Illimani glacier (6350 m a.s.l) in the Cordillera Real, Bolivia. The two sites are ~450 km apart. Despite meltwater percolation resulting from warming, particle-based trace element records (e.g. Fe, Mg, K) in the Quelccaya and Illimani shallow cores retain well-preserved signals. The firn core chronologies, established independently by annual layer counting, show a convincing overlap indicating the two records contain comparable signals and therefore capture similar regional scale climatology. Trace element records at a ~1?4 cm resolution provide past records of anthropogenic emissions, dust sources, volcanic emissions, evaporite salts and marine-sourced air masses. Using novel ultra-high-resolution (120 ?m) laser technology, we identify annual layer thicknesses ranging from 0.3 to 0.8 cm in a section of 2000-year-old radiocarbon-dated near-basal ice which compared to the previous annual layer estimates suggests that Quelccaya ice cores drilled to bedrock may be older than previously suggested by depth-age models. With the information collected from this study in combination with past studies, we emphasize the importance of collecting new surface-to-bedrock ice cores from at least the Quelccaya ice cap, in particular, due to its projected disappearance as soon as the 2050s

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to &lt;90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], &gt;300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of &lt;15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P&lt;0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P&lt;0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Composição isotópica da precipitação no Rio Grande do Sul: investigar a origem da umidade em eventos normais e extremos de precipitação

Eventos extremos de precipitação possuem grande potencial destrutivo no Estado do Rio Grande do Sul (RS), visto que o RS está geograficamente localizado em uma região de encontro de massas de ar de continentais e marítimas de naturezas distintas: tropical e subpolar. Desta forma, são frequentes episódios de desastres naturais, tanto no verão quanto nas estações de transição (outono e primavera). Estes períodos também coincidem com a temporada de atuação de sistemas convectivos, e em especial os Complexos Convectivos de Mesoescala (CCM), no RS. Não se possui muitas informações acerca das fontes de umidade dos sistemas meteorológicos que atuam sobre o RS, com base nisso, propõe-se realizar uma análise do comportamento isotópico do oxigênio presente na água que precipita na cidade de Porto Alegre para pesquisar-se a fonte da umidade responsável pela precipitação em eventos regulares e extremos, como os CCM, no RS

Composição e análise isotópica da precipitação mensal em Porto Velho-RO entre outubro de 2013 e maio de 2014

O ciclo hidrológico que ocorre na Amazônia é regulado por ventos que sopram no sentido Leste-Oeste, responsáveis por trazer vapor d’água proveniente da evaporação do Oceano Atlântico Tropical. No interior do continente, a água precipita, evapora e recicla. Parte da água que cai sobre a Amazônia, onde está inserida Porto Velho, tem fonte no oceano e parte é proveniente de fontes internas à bacia. Este trabalho relaciona, através da análise de isótopos estáveis de oxigênio, os valores de δ18O medidos a partir de amostras colhidas mensalmente entre outubro de 2013 e maio de 2014, com dados ambientais de temperatura e precipitação a fim de relacionar a variação deste isótopo estável na precipitação com as variações meteorológicas locais

Razões de isótopos estáveis em um testemunho de firn do manto de gelo da Antártica Oriental

O testemunho de firn IC-02 (88°01’21,3"S e 82°04’21,7"W), atingindo 41,82 m de profundidade, foi coletado no manto de gelo da Antártica Oriental, durante uma travessia científica chileno-brasileira no verão austral de 2004/2005. Este estudo visou à determinação da variabilidade sazonal das razões isotópicas de oxigênio e hidrogênio (ẟ18O e ẟD) e da taxa anual de acumulação de neve. O testemunho foi subamostrado em um sistema de fusão contínua e o conteúdo isotópico determinado por espectrometria a laser de cavidade ressonante do tipo ring-down (WS-CRDS, sistema Picarro). A série de ẟ18O varia entre ‑50,77‰ e ‑41,40‰ (média -46,39 ± 1,37‰), enquanto o ẟD varia entre -408,18‰ e ‑323,85‰ (média -367,43 ± 12,51‰). O excesso de deutério (d) tem média de 4,36 ± 2,66‰. O testemunho representa 85 ± 3 anos de acumulação de neve, ou seja, uma taxa média de 152 ± 64 mm ano‑1 em equivalente d'água. A partir da década de 1990 ocorreu a diminuição da média anual de δD concomitante com o aumento da taxa de acumulação de neve (17% entre 1974 e 2003). O aumento desta acumulação poderia estar associado à maior mobilização de neve à deriva (drift snow) até o sítio de deposição, associada à maior advecção de massas de ar oceânicas vindas dos mares antárticos (Amundsen, Bellingshausen, Weddell e Lazarev). Tal interpretação é apoiada pelo aumento da velocidade dos ventos zonais, conforme observado nos campos de anomalias de altura geopotencial, vento zonal e temperatura em 500 mb da reanálise NCEP/NCAR