The insular Caribbean experiences numerous climate and environmental hazards, including but not limited to hurricanes, floods, earthquakes, and drought. While some hazards are well explored in ...scientific literature, drought is considered one of the neglected hazards because of the lack of studies focusing on its causes and effects. This study identifies the spatial distribution of seasonal drought in insular Caribbean from 1950 to 2017, and its relationship with eastern Pacific (EP) and central Pacific (CP) ENSO, North Atlantic Oscillation (NAO), and Atlantic Meridional Mode (AMM). It brings a new perspective over the region by dividing the Caribbean into Greater Antilles and Bahamas (GA), and the Lesser Antilles (LA) to compare the role of those three teleconnection patterns on drought events over larger versus smaller islands. We used an existing high‐resolution drought atlas (4 km) based on monthly estimates of the self‐calibrating Palmer Drought Severity Index (scPDSI). Results indicate that there is a drying trend in all seasonal‐average scPDSI for both the GA and the LA, but more intense and frequent drought events occur in the LA. The LA is also the region with more widespread drought events, registering 12 years when the mid‐summer dry spell (MSD; July–August) had drought ≥80% of the area, while the GA registered only 2 years of MSD drought that extensive. The peak season AMM had the strongest positive correlation with GA and LA drought during April–November, while NAO was slightly stronger correlated with GA than with LA from July–November. For ENSO, CP El Niño years related stronger with drought in the LA from December–July, while the relationship between the two types of ENSO and the GA was not statistically significant. This effort aims to improve drought forecasts to help the region to better prepare for the prediction of seasonal droughts.
Drought is considered one of the neglected hazards in the insular Caribbean because of the lack of studies focusing on its causes and effects. However, this study shows that there is a drying trend in the region since 1950, and the smaller islands are suffering with more frequent, intense, and widespread drought events when compared to the larger islands. Among the teleconnection patterns, the negative phase of Atlantic Meridional Mode is the one most strongly correlated with seasonal drought events.
Abstract The shape of the secondary sexual characters is, traditionally, used to discriminate the marine shrimps at the species level. However, the qualitative evaluation of structures that are ...morphologically variable in the taxonomy of species can favor misunderstandings and misidentifications. These possibilities of taxonomic inaccuracies are especially alarming when there is a need to evaluate the invasion of introduced species. The present study used geometric morphometric analyses to identify differences in the cephalothorax shape that would help discriminate the native and non-native species of Litopenaeus of the South American coast. The comparative morphology analysis was conducted using the right profile of adult males’ cephalothorax of L. schmitti, captured in the natural environment, and L. vannamei captured in the natural environment or grown in shrimp farms. In intraspecific evaluation, it was not possible to distinguish the specimens of L. vannamei that were grown in shrimp farms from those acclimated to the natural environment. However, significant interspecific differences in shape were found in the shape of this body structure. Additionally, the base position of the first rostral spine to the tip of the hepatic spine is indicated as a characteristic that can be used to distinguish these two species by eye in the field.
Abstract Alpinia zerumbet is a plant popularly used to treat hypertension and anxiety. Studies with Alpinia zerumbet demonstrate antihypertensive and vasodilator effects, among others. The objective ...of this study was to analyze the effect of essential oil of Alpinia zerumbet (EOAz) on cardiovascular and autonomic function in rats with isoproterenol-induced myocardial infarction. Male Wistar rats (n=32) were equally allocated into four groups: Control, ISO (150mg/kg, subcutaneous), EOAz (100mg/kg by gavage), ISO+EOAz. The rats were evaluated for cardiovascular and, autonomic parameters, electrocardiogram, and infarct size. EOAz was not able to reduce the electrocardiographic variations induced by ISO. Heart rate variability showed a decrease in sympathetic modulation on the heart in the groups treated with EOAz. The cardiopulmonary reflex induced by serotonin invoked a superior blood pressure variation at the 2 µg/kg dose in the EOAz treated groups, while the heart rate variation was significantly higher at the 16 µg/kg dose, when compared to other doses, in all groups, except EOAz+ISO. The sympathetic vagal index was higher in ISO group than in control. EOAz did not reduce the infarct size. We conclude that pretreatment with EOAz does not reverse the hemodynamic and electrocardiographic damage caused by isoproterenol but does reduce sympathetic modulation.
This study evaluated the nutritional and productive performance of Nellore purebred heifers and crossbred Brangus x Nellore (BGNE) and Braford x Nellore (BFNE) in a feedlot system. Thirty heifers (10 ...of each genetic group) with an average age of 18 months and an initial body weight of 261 kg were used. The experiment was structured and conducted according to a completely randomized design, with three treatments. Heifers received two diets (60 days each) during the experimental period. The experiment lasted 120 days with four experimental periods. Nellore heifers had a lower intake than crossbred heifers (P <0.05). There were no differences between BGNE and BFNE heifers, which had higher final body weight, average daily gain, feed efficiency, hot carcass weight and carcass length than NE heifers. Crossed heifers presented better fat cover than NE heifers. However, NE heifers had higher carcass dressing Despite presenting lower carcass yields than Nellore heifers, crossed heifers are more efficient and have higher performance and better fat cover on the carcass than purebred Nellore heifers. Crossbreeding synthetic breeds, such as Brangus and Braford breeds, with the Nellore breed is an effective way to increase the productivity and efficiency of feedlot heifers in tropical regions.
The objective of this study was to examine the effects of extrinsic or intrinsic acids on nanofilled and bulk fill resin materials in vitro. A total of 90 disks were prepared using dental restorative ...material (Filtek Z350XT, GrandioSO, Filtek Bulk Fill, X‐tra fil). Thirty disks of each material were sub‐divided into three groups (n = 10) that were immersed for 7 days in deionized water (DW), 5% citric acid (CA—pH 2.1), or 0.1% hydrochloric acid (HCl—pH = 1.2). Surface hardness and roughness (stylus profilometer by Ra parameter) analysis were performed before and after immersion. Morphological changes were evaluated by scanning electron microscopy. The data were analyzed by two‐way ANOVA and Tukey's test (α = 0.05). All tested materials did not show significant differences in the effects of the DW, CA, or HCl solutions on surface roughness (p = .368). Likewise, the hardness loss was not affected by the solutions tested (p = .646), but there was a difference in the resin type (p = .002). Filtek Bulk Fill resin hardness was less affected, while Filtek Z350XT and GrandioSO presented the most hardness loss after 7 days of solution immersion. In terms of this experimental study, the results demonstrate the effectiveness of the mechanical properties (roughness and hardness surface) of nanofilled and bulk fill resin materials to resist erosion from extrinsic and intrinsic acids, therefore being potential candidates for dental applications.
The main finding of the study suggests that the resins tested have good physical properties to be used for dental applications, which are under constant acid challenge.
The absence of companion may jeopardize mental health in social animals. Here, we tested the hypothesis that social isolation impairs social recognition memory by altering the excitability and the ...dialog between the olfactory bulb (OB) and the dorsal hippocampus (dHIP). Adult male Swiss mice were kept grouped (GH) or isolated (SI) for 7 days. Social memory (LTM) was evaluated using social recognition test. SI increased glutamate release in the OB, while decreased in the dHIP. Blocking AMPA and NMDA receptors into the OB or activating AMPA into the dHIP rescued LTM in SI mice, suggesting a cause-effect relationship between glutamate levels and LTM impairment. Additionally, during memory retrieval, phase-amplitude coupling between OB and dHIP decreased in SI mice. Our results indicate that SI impaired the glutamatergic signaling and the normal communication between OB and HIP, compromising the persistence of social memory.
Hexavalent chromium adsorption in aqueous solution was studied in a fixed bed column with a hydrotalcite-hydroxyapatite (HT-HAp) material doped with carbon nanotubes (CNT) at 333.15 K. Equilibrium, ...kinetic and thermodynamic behaviors were the focus of this work. The CNT doping was performed in two different proportions (5 and 15%wt.). Isotherm (Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, and Toth) and kinetics (Thomas, Yoon-Nelson, and Adams–Bohart) models were tested. HT-HAp/CNT15 sample presented the best Cr(VI) bated proportion (76.97%R). The adsorption behavior was fit by the Freundlich model, following a pseudo-second order kinetic mechanism confirmed by Thomas model. Thermodynamic parameters indicated a physisorption process.
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•Hydrotalcite and hydroxyapatite were doped with carbon nanotubes (HT-HAp/CNT).•The use of HT-HAp/CNT as Cr(VI) adsorbent is discussed.•The adsorption efficiency increases with the doped CNT content (≈77% at 333.15 K).•HT-HAp doped with CNT is an alternative for Cr(VI) decontamination of wastewater.
Most deforested lands in Brazil are occupied by low-productivity cattle ranching. Brazil is the second biggest meat producer worldwide and is projected to increase its agricultural output more than ...any other country. Biochar has been shown to improve soil properties and agricultural productivity when added to degraded soils, but these effects are context-dependent. The impact of biochar, fertilizer and inoculant on the productivity of forage grasses in Brazil (Brachiaria spp. and Panicum spp.) was investigated from environmental and socio-economic perspectives. We showed a 27% average increase in Brachiaria production over two years but no significant effects of amendment on Panicum yield. Biochar addition also increased the contents of macronutrients, soil pH and CEC. Each hectare amended with biochar saved 91 tonnes of CO
eq through land sparing effect, 13 tonnes of CO
eq sequestered in the soil, equating to U$455 in carbon payments. The costs of biochar production for smallholder farmers, mostly because of labour cost, outweighed the potential benefits of its use. Biochar is 617% more expensive than common fertilizers. Biochar could improve productivity of degraded pasturelands in Brazil if investments in efficient biochar production techniques are used and biochar is subsidized by low emission incentive schemes.
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