978 resultados para natural control
Resumo:
For the past 49 years, the Connecticut Poison Control Center (CTPCC) based at the University of Connecticut Health Center (UCHC), has managed human exposures and poisonings throughout the state and continues to serve as a toxicologic center of excellence. A human exposure may be defined as contact by skin, eye, mouth or inhalation to any substance: animal, mineral or vegetable, including: bites, commercial products, chemicals, drugs, natural remedies and plants among others. A poisoning is any injury to the body resulting from an exposure. Toxicology is the scientific study of the adverse effects of any substance on the body.
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The natural history of placebo treated travelers' diarrhea and the prognostic factors of recovery from diarrhea were evaluated using 9 groups of placebo treated subjects from 9 clinical trial studies conducted since 1975, for use as a historical control in the future clinical trial of antidiarrheal agents. All of these studies were done by the same group of investigators in one site (Guadalajara, Mexico). The studies are similar in terms of population, measured parameters, microbiologic identification of enteropathogens and definitions of parameters. The studies had two different durations of followup. In some studies, subjects were followed for two days, and in some they were followed for five days.^ Using definitions established by the Infectious Diseases society of America and the Food and Drug Administration, the following efficacy parameters were evaluated: Time to last unformed stool (TLUS), number of unformed stools post-initiation of placebo treatment for five consecutive days of followup, microbiologic cure, and improvement of diarrhea. Among the groups that were followed for five days, the mean TLUS ranged from 59.1 to 83.5 hours. Fifty percent to 78% had diarrhea lasting more than 48 hours and 25% had diarrhea more than five days. The mean number of unformed stools passed on the first day post-initiation of therapy ranged from 3.6 to 5.8 and, for the fifth day ranged from 0.5 to 1.5. By the end of followup, diarrhea improved in 82.6% to 90% of the subjects. Subjects with enterotoxigenic E. coli had 21.6% to 90.0% microbiologic cure; and subjects with shigella species experienced 14.3% to 60.0% microbiologic cure.^ In evaluating the prognostic factors of recovery from diarrhea (primary efficacy parameter in evaluating the efficacy of antidiarrheal agents against travelers' diarrhea). The subjects from five studies were pooled and the Cox proportional hazard model was used to evaluate the predictors of prolonged diarrhea. After adjusting for design characteristics of each trial, fever with a rate ratio (RR) of 0.40, presence of invasive pathogens with a RR of 0.41, presence of severe abdominal pain and cramps with a RR of 0.50, number of watery stools more than five with a RR of 0.60, and presence of non-invasive pathogens with a RR of 0.84 predicted a longer duration of diarrhea. Severe vomiting with a RR of 2.53 predicted a shorter duration of diarrhea. The number of soft stools, presence of fecal leukocytes, presence of nausea, and duration of diarrhea before enrollment were not associated with duration of diarrhea. ^
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Extreme winter warming events in the sub-Arctic have caused considerable vegetation damage due to rapid changes in temperature and loss of snow cover. The frequency of extreme weather is expected to increase due to climate change thereby increasing the potential for recurring vegetation damage in Arctic regions. Here we present data on vegetation recovery from one such natural event and multiple experimental simulations in the sub-Arctic using remote sensing, handheld passive proximal sensors and ground surveys. Normalized difference vegetation index (NDVI) recovered fast (2 years), from the 26% decline following one natural extreme winter warming event. Recovery was associated with declines in dead Empetrum nigrum (dominant dwarf shrub) from ground surveys. However, E. nigrum healthy leaf NDVI was also reduced (16%) following this winter warming event in experimental plots (both control and treatments), suggesting that non-obvious plant damage (i.e., physiological stress) had occurred in addition to the dead E. nigrum shoots that was considered responsible for the regional 26% NDVI decline. Plot and leaf level NDVI provided useful additional information that could not be obtained from vegetation surveys and regional remote sensing (MODIS) alone. The major damage of an extreme winter warming event appears to be relatively transitory. However, potential knock-on effects on higher trophic levels (e.g., rodents, reindeer, and bear) could be unpredictable and large. Repeated warming events year after year, which can be expected under winter climate warming, could result in damage that may take much longer to recover.
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La finalidad de este trabajo fué determinar las especies parásitas e hiperparásitas del "bicho del cesto" común, Oiketicus Kirbyi Guild, en Mendoza, a fin de obtener supervivencia de la que se encuentra en mayor número e intensidad. Como resultado de estas investigaciones se comprobó que el calcídido Psychidosmicra Brethesi Blanchard constituye un eficáz enemigo específico del psíquico, llegándose a la conclusión que debe preservarse dicho material por el método de aislamiento en su época oportuna, permitiendo esto incrementar las poblaciones por dispersión artificial y atenuar la acción del factor hiperparasitismo.
Resumo:
Los suelos en los cuales se desarrolla la actividad hortícola en el Gran La Plata presentan como limitante natural restricciones en el drenaje debido a la presencia de elevada cantidad de arcillas desde superficie (expansivas en alta proporción). Estas características edáficas, junto a la calidad del agua de riego, y al excesivo aporte de enmiendas y fertilizantes, conducen a la ocurrencia de procesos degradativos tales como, salinización, alcalinización, anegamiento, mayor incidencia de plagas, y efectos sobre el cultivo. Se tuvo como objetivo estudiar la eficiencia de drenes subsuperficiales en el control de la salinidad-alcalinidad de un suelo Hapludert típico con cultivos protegidos, que presentaba en promedio pH 8,25; CE 4,45 dS.m-1; RAS 22, aunque con amplia variabilidad. Se comparan dos tratamientos con drenes (T1 10cm y T2 15cm de diámetro), un tratamiento con yeso (T3) y un testigo. Se evaluó el suelo y el cultivo de pimiento "Capsicum annuum" durante 3 años (2009-2011). Los drenes subsuperficiales condujeron a una homogenización de todo el sitio de estudio y evitaron la ocurrencia de pulsos salinos característicos de estos sistemas productivos, sin ocasionar cambios significativos en la RAS, la cual se mantuvo en los valores dados por el agua de riego. El diámetro del dren no influyó de una manera significativa. El yeso presentó mejoras temporales en la salinidad-alcalinidad, pero no condujo a una mejora permanente del sitio. El desarrollo fenológico y rendimiento del cultivo en los tratamientos fue mejor que en el testigo en los años evaluados. Los tratamientos con drenes se diferenciaron significativamente del yeso en 2009 (P 0,01). El distanciamiento entre drenes (5m), resultó suficiente como para mejorar todo el invernáculo (460m2).
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Slowslip forms part of the spectrum of fault behaviour between stable creep and destructive earthquakes. Slow slip occurs near the boundaries of large earthquake rupture zones and may sometimes trigger fast earthquakes. It is thought to occur in faults comprised of rocks that strengthen under fast slip rates, preventing rupture as a normal earthquake, or on faults that have elevated pore-fluid pressures. However, the processes that control slow rupture and the relationship between slow and normal earthquakes are enigmatic. Here we use laboratory experiments to simulate faulting in natural rock samples taken from shallow parts of the Nankai subduction zone, Japan, where very low-frequency earthquakes - a form of slow slip - have been observed.We find that the fault rocks exhibit decreasing strength over millimetre-scale slip distances rather than weakening due to increasing velocity. However, the sizes of the slip nucleation patches in our laboratory simulations are similar to those expected for the very lowfrequency earthquakes observed in Nankai. We therefore suggest that this type of fault-weakening behaviour may generate slow earthquakes. Owing to the similarity between the expected behaviour of slow earthquakes based on our data, and that of normal earthquakes during nucleation, we suggest that some types of slow slip may represent prematurely arrested earthquakes.
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Ocean acidification (OA) is not an isolated threat, but acts in concert with other impacts on ecosystems and species. Coastal marine invertebrates will have to face the synergistic interactions of OA with other global and local stressors. One local factor, common in coastal environments, is trace element contamination. CO2 vent sites are extensively studied in the context of OA and are often considered analogous to the oceans in the next few decades. The CO2 vent found at Levante Bay (Vulcano, NE Sicily, Italy) also releases high concentrations of trace elements to its surrounding seawater, and is therefore a unique site to examine the effects of long-term exposure of nearby organisms to high pCO2 and trace element enrichment in situ. The sea anemone Anemonia viridis is prevalent next to the Vulcano vent and does not show signs of trace element poisoning/stress. The aim of our study was to compare A. viridis trace element profiles and compartmentalization between high pCO2 and control environments. Rather than examining whole anemone tissue, we analyzed two different body compartments-the pedal disc and the tentacles, and also examined the distribution of trace elements in the tentacles between the animal and the symbiotic algae. We found dramatic changes in trace element tissue concentrations between the high pCO2/high trace element and control sites, with strong accumulation of iron, lead, copper and cobalt, but decreased concentrations of cadmium, zinc and arsenic proximate to the vent. The pedal disc contained substantially more trace elements than the anemone's tentacles, suggesting the pedal disc may serve as a detoxification/storage site for excess trace elements. Within the tentacles, the various trace elements displayed different partitioning patterns between animal tissue and algal symbionts. At both sites iron was found primarily in the algae, whereas cadmium, zinc and arsenic were primarily found in the animal tissue. Our data suggests that A. viridis regulates its internal trace element concentrations by compartmentalization and excretion and that these features contribute to its resilience and potential success at the trace element-rich high pCO2 vent.
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Low seawater pH can be harmful to many calcifying marine organisms, but the calcifying macroalgae Padina spp. flourish at natural submarine carbon dioxide seeps where seawater pH is low. We show that the microenvironment created by the rolled thallus margin of Padina australis facilitates supersaturation of CaCO3 and calcifi-cation via photosynthesis-induced elevated pH. Using microsensors to investigate oxygen and pH dynamics in the microenvironment of P. australis at a shallow CO2 seep, we found that, under saturating light, the pH inside the microenvironment (pHME) was higher than the external seawater (pHSW) at all pHSW levels investigated, and the difference (i.e., pHME-pHSW) increased with decreasing pHSW (0.9 units at pHSW 7.0). Gross photosynthesis (Pg) inside the microenvironment increased with decreasing pHSW, but algae from the control site reached a threshold at pH 6.5. Seep algae showed no pH threshold with respect to Pg within the pHSW range investigated. The external carbonic anhydrase (CA) inhibitor, acetazolamide, strongly inhibited Pg of P. australis at pHSW 8.2, but the effect was diminished under low pHSW (6.4-7.5), suggesting a greater dependence on membrane-bound CA for the dehydration of HCO3- ions during dissolved inorganic carbon uptake at the higher pHSW. In comparison, a calcifying green alga, Halimeda cuneata f. digitata, was not inhibited by AZ, suggesting efficient bicarbonate transport. The ability of P. australis to elevate pHME at the site of calcification and its strong dependence on CA may explain why it can thrive at low pHSW.
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In the early stages of the development of Japan’s environmental policy, sulfur oxide (SOx) emissions, which seriously damage health, was the most important air pollution problem. In the second half of the 1960s and the first half of the 1970s, the measures against SOx emissions progressed quickly, and these emissions were reduced drastically. The most important factor of the reduction was the conversion to a low-sulfur fuel for large-scale fuel users, such as the electric power industry. However, industries started conversion to low-sulfur fuel not due to environmental concerns, but simply to reduce costs. Furthermore, the interaction among the various interests of the electric power industry, oil refineries, the central government, local governments, and citizens over the energy and environmental policies led to the measures against SOx emissions by fuel conversion.
Resumo:
Pesticide applications are still one of the most common control methods against the main olive grove pests and diseases: the olive fruit fly, Bactrocera oleae (Rossi), the olive moth, Prays oleae (Bernard), the black scale, Saissetia oleae (Olivier), and the olive leaf spot, caused by the fungus Spilocaea oleagina Fries. However, and because the new pesticide legislation is aimed at an integrated pest and disease management, it is still important to evaluate and to know the ecotoxicology of pesticides on the natural enemies of the different agrosystems. A part of this work has been focusses on evaluating the direct and indirect effects of kaolin particle films and two copper-based products (Bordeaux mixture and copper oxychloride) through different laboratory, extended laboratory and semi-field experiments. Two natural enemies have been chosen: Psyttalia concolor (Szèpligeti), a parasitoid of the olive fruit fly, and Chilocorus nigritus (F.), predator of Diaspididae. This predator has been used instead of C. bipustulatus (L.), which is the species found in olive orchards. Kaolin mainly acts as a repellent of insects and/or as an oviposition deterrent. It is used in olive groves to control the olive fruit fly and the olive moth. Copper is applied against fungal and bacterial diseases. In olive groves it is used against the olive leaf spot and other diseases. No statistical differences were found in any of the experiments performed, compared to the controls, except when the oral toxicity of the products was evaluated on P. concolor females. In this case, kaolin and copper oxychloride caused a higher mortality 72 hours after the treatments, and both kaolin and the two copper formulations decreased females’ life span. Reproductive parameters were only negatively affected when kaolin was ingested. Apart from these experiments, due to the uncommon mode of action of kaolin, two extra experiments were carried out: a dual choice and a no-choice experiment. In this case, both P. concolor females and C. nigritus adults showed a clear preference for the untreated surfaces when they had the possibility of choosing between a treated surface and an untreated one. When there was no choice, no statistical differences were found between the treatments and the controls. Furthermore, the efficacy and the selectivity of three insect growth regulators (methoxyfenozide, tebufenozide and RH-5849) on B. oleae and P. concolor, respectively, have also been evaluated. In addition to laboratory experiments to evaluate the toxicity of the insecticides, also molecular approaches were used. RNA of both insects was isolated. cDNA was subsequently synthesized and the complete sequences of the ligand biding domain (LBD) of the ecdysone receptor of each insect were then determined. Afterwards the three dimensional structures of both LBDs were constructed. Finally, the docking of the insecticide molecules in the cavity delineated by the 12 α-helix that composed the LBD was performed. Both toxicity assays and molecular docking approaches showed that either methoxyfenozide or tebufenozide had no negative effects nor on B. oleae nor on P. concolor. In contrast, RH-5849 had no deleterious effect to the parasitoid but decreased olive fruit fly adults’ life span, especially when they were in contact with the fresh residue of the insecticide applied on a glass surface. The docking study of RH-5849 molecule has shown a very light hindrance with the wall of the LBD pocket. This means that this molecule could more or less adjust in the cavity. Thus, searching of new insecticides for controlling the olive fruit fly could be based on the basic lead structure of RH-5849 molecule.
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All-terrain robot locomotion is an active topic of research. Search and rescue maneuvers and exploratory missions could benefit from robots with the abilities of real animals. However, technological barriers exist to ultimately achieving the actuation system, which is able to meet the exigent requirements of these robots. This paper describes the locomotioncontrol of a leg prototype, designed and developed to make a quadruped walk dynamically while exhibiting compliant interaction with the environment. The actuation system of the leg is based on the hybrid use of series elasticity and magneto-rheological dampers, which provide variable compliance for natural-looking motion and improved interaction with the ground. The locomotioncontrol architecture has been proposed to exploit natural leg dynamics in order to improve energy efficiency. Results show that the controller achieves a significant reduction in energy consumption during the leg swing phase thanks to the exploitation of inherent leg dynamics. Added to this, experiments with the real leg prototype show that the combined use of series elasticity and magneto-rheologicaldamping at the knee provide a 20 % reduction in the energy wasted in braking the knee during its extension in the leg stance phase.
Resumo:
El presente proyecto trata de un estudio de las distintas técnicas de monitorización superficial para la caracterización de fugas en un análogo natural. Tiene como objetivo la extrapolación de los resultados a un sistema de almacenamiento geológico de CO2. Para ello, se realizaron medidas en el área del análogo y sus alrededores para analizar la capacidad de detección de fuga de cada instrumento. A partir de esas mediciones y de las propiedades técnicas y económicas de cada método de monitorización, se determinó cuáles son los más recomendables para utilizar en una campaña inicial, de investigación o de seguimiento de caracterización superficial de un futuro sistema de almacenamiento. ABSTRACT This project is about the study of the different types of superficial monitoring techniques for the leakage characterization in a natural analogue. It aims to extrapolate the results to a geological storage system of CO2. For that purpose, measurements were made in the surrounding area of the analogue to analyze the ability of each leak detection instrument. From these measurements and the technical-economics features of each monitoring method, we established what are the most suitable for use in an initial, research or follow-up campaign of surface characterization of a future storage system.
Resumo:
Con patógenos de origen telúrico o edáfico nos referimos a aquéllos establecidos en plantaciones en suelo natural, suelo modificado o en cultivos sobre sustratos. Se pueden clasificar según afecten a la raíz, cuello o base del tallo, siendo indiferentes a la presencia de agua libre o actuando únicamente en condiciones de encharcamiento, o afectar al sistema vascular, entre los que se encuentran el conocido Verticilium dahliae o la compleja especie denominada Fusarium.