132 research outputs found
Diagnóstico da área cultivada com uva fina de mesa (Vitis vinifera L.) sob cobertura plástica e do manejo de pragas.
Neste trabalho, foi realizado o censo das áreas cultivadas com uvas finas de mesa sob cultivo protegido e a identificação das principais espécies de pragas e estratégias de controle empregadas pelos produtores, no município de Caxias do Sul-RS. Na safra de 2007/2008, foram identificados os produtores envolvidos com a atividade no município e através de entrevista presencial e semiestruturada ao estabelecimento produtivo, registrou-se a área cultivada e variedades. Para produtores com cultivo de áreas superiores a 2.000m2 da cultivar Itália, com dois anos ou mais de produção, foi aplicado outro questionário na safra de 2008/2009 com o objetivo de levantar as informações referentes: a) espécies de insetos e ácarospraga que danificam as uvas finas de mesa na propriedade, segundo o viticultor; b) conhecer a realidade do manejo de insetos e ácaros-praga na cultura; c) verificar os parâmetros que o produtor utiliza para a aplicação de inseticidas; d) conhecer os produtos aplicados, e e) identificar o tipo de assistência técnica recebida pelo viticultor. Foram identificados 43 produtores de uvas finas de mesa sob cultivo protegido com área total cultivada de 30,36 ha, sendo 70,31% desta área da cultivar Itália. As pragas mais importantes mencionadas pelos produtores foram tripes - Frankliniella rodeos Moulton e a mosca-das-frutas-sul-americana Anastrepha fraterculus (Wied). O manejo realizado para controle destas pragas é através da aplicação de inseticidas com os ingredientes ativos acefato e fentiona, respectivamente, com base em calendário. Os principais problemas enfrentados para implementar estratégias de manejo de pragas no cultivo são a falta de assistência técnica, a ausência de metodologias confiáveis para o monitoramento e o reduzido número de inseticidas autorizados para a cultura
Position-Specific Hydrogen Isotope Equilibrium in Propane
Intramolecular isotope distributions can constrain source attribution, mechanisms of formation and destruction, and temperature-time histories of molecules. In this study, we explore the D/H fractionation between central (-CH_2-) and terminal (-CH_3) positions of propane (C_3H_8)- a percent level component of natural gases. The temperature dependenceof position-specific D/H fractionation of propane could potentially work as a geo-thermometer for natural gas systems, and a forensic identifier of specific thermogenic sources of atmospheric or aquatic emissions. Moreover, kinetically controlled departures from temperature dependent equilibrium might constrain mechanisms of thermogenic production, or provide indicators of biological or photochemical destruction. We developed a method to measure position-specific D/H differences of propane with high-resolution gas source mass spectrometry. We performed laboratory exchange experiments to study the exchange ratesfor both terminal and central positions, and used catalysts to drive the hydrogen isotopedistribution of propane to thermodynamic equilibrium. Experimental results demonstrate that D/H exchange between propane and water happens easily in the presence of either Pd catalyst or Ni catalyst. Exchange rates are similar between the two positions catalyzed by Pd. However, the central position exchanges 2.2 times faster than the terminal position in the presence of Ni catalyst. At 200 °C in the presence of Pd catalyst, the e-folding time of propane-water exchange is 20 days and of homogeneous exchange (i.e., equilibrium between central and terminal positions) is 28 min. An equilibrated (bracketed and time-invariant) intramolecular hydrogen isotope distribution was attained for propane at three temperatures, 30 °C, 100 °C and 200 °C; these data serve as an initial experimental calibration of a new position-specific thermometer with a temperature sensitivity of 0.25‰ per °C at 100 °C. We use this calibration to test the validity of prior published theoretical predictions. Comparison of data with models suggest the most sophisticated of these discrepant models (Webb and Miller, 2014) is most accurate; this conclusion implies that there is a combined experimental and theoretical foundation for an ‘absolute reference frame’ for position-specific H isotope analysis of propane, following principles previously used for clumped isotope analysis of CO_2, CH_4 and O_2 (Eiler and Schauble, 2004; Yeung et al., 2014; Stolper et al., 2014)
Sulfur cycling in an iron oxide-dominated, dynamic marine depositional system: The Argentine continental margin
The interplay between sediment deposition patterns, organic matter type and the quantity and quality of reactive mineral phases determines the accumulation, speciation, and isotope composition of pore water and solid phase sulfur constituents in marine sediments. Here, we present the sulfur geochemistry of siliciclastic sediments from two sites along the Argentine continental slope—a system characterized by dynamic deposition and reworking, which result in non-steady state conditions. The two investigated sites have different depositional histories but have in common that reactive iron phases are abundant and that organic matter is refractory—conditions that result in low organoclastic sulfate reduction rates (SRR). Deposition of reworked, isotopically light pyrite and sulfurized organic matter appear to be important contributors to the sulfur inventory, with only minor addition of pyrite from organoclastic sulfate reduction above the sulfate-methane transition (SMT). Pore-water sulfide is limited to a narrow zone at the SMT. The core of that zone is dominated by pyrite accumulation. Iron monosulfide and elemental sulfur accumulate above and below this zone. Iron monosulfide precipitation is driven by the reaction of low amounts of hydrogen sulfide with ferrous iron and is in competition with the oxidation of sulfide by iron (oxyhydr)oxides to form elemental sulfur. The intervals marked by precipitation of intermediate sulfur phases at the margin of the zone with free sulfide are bordered by two distinct peaks in total organic sulfur (TOS). Organic matter sulfurization appears to precede pyrite formation in the iron-dominated margins of the sulfide zone, potentially linked to the presence of polysulfides formed by reaction between dissolved sulfide and elemental sulfur. Thus, SMTs can be hotspots for organic matter sulfurization in sulfide-limited, reactive iron-rich marine sedimentary systems. Furthermore, existence of elemental sulfur and iron monosulfide phases meters below the SMT demonstrates that in sulfide-limited systems metastable sulfur constituents are not readily converted to pyrite but can be buried to deeper sediment depths. Our data show that in non-steady state systems, redox zones do not occur in sequence but can reappear or proceed in inverse sequence throughout the sediment column, causing similar mineral alteration processes to occur at the same time at different sediment depths
Simulating crowd evacuation with socio-cultural, cognitive, and emotional elements
In this research, the effects of culture, cognitions, and emotions on crisis management and prevention are analysed. An agent-based crowd evacuation simulation model was created, named IMPACT, to study the evacuation process from a transport hub. To extend previous research, various socio-cultural, cognitive, and emotional factors were modelled, including: language, gender, familiarity with the environment, emotional contagion, prosocial behaviour, falls, group decision making, and compliance. The IMPACT model was validated against data from an evacuation drill using the existing EXODUS evacuation model. Results show that on all measures, the IMPACT model is within or close to the prescribed boundaries, thereby establishing its validity. Structured simulations with the validated model revealed important findings, including: the effect of doors as bottlenecks, social contagion speeding up evacuation time, falling behaviour not affecting evacuation time significantly, and travelling in groups being more beneficial for evacuation time than travelling alone. This research has important practical applications for crowd management professionals, including transport hub operators, first responders, and risk assessors
Geochemical applications in petroleum systems analysis: new constraints and the power of integration
This paper provides an overview of the role that geochemistry plays in petroleum systems analysis, and how this can be used to derive constraints on the key elements and processes that give rise to a successful petroleum system. We discuss the history of petroleum geochemistry before reflecting on the next frontier in geochemical applications in hydrocarbon systems. We then review the individual contributions to this Special Publication. These papers present new geochemical techniques that allow us to develop a more systematic understanding of critical petroleum system elements; including the temperature and timing of source-rock deposition and maturation, the mechanisms and timescales associated with hydrocarbon migration, trapping, storage and alteration, and the impact of fluid flow on reservoir properties. Finally, we provide a practical example of how these different geochemical techniques can be integrated to constrain and generate a robust understanding of the prolific Paleozoic petroleum system of the Bighorn Basin
The accident insurance as a promising direction for insurance in Russia
Статья посвящена анализу состояния рынка услуг страхования от несчастных случаев. Актуальность исследования определяется тем, что страхование является неотъемлемым атрибутом цивилизованного общества, позволяющим сохранить обеспеченность доходами при неблагоприятных ситуациях. По статистике в России уровень травматизма и непредвиденных обстоятельств весьма велик. Люди традиционно уделяют мало внимания формированию резервов на случай временной или постоянной нетрудоспособности. Цель работы: рассмотреть систему страхования от несчастных случаев. Методы исследования: метод сопоставления, необходимый для выявления главных тенденций на рынке страховых услуг; аналитический метод, позволяющий понять, какие проблемы характерны для этого вида страхования; статистический метод, выявляющий масштабы страхования от несчастных случаев. Результаты: раскрывается сущность и виды страхования от несчастных случаев.The article is devoted to analysis of service market of accident insurance. The relevant of the study is determined by the fact that insurance is an integral attribute of a civilized society that allows you to save security income in adverse situations. According to statistics, in Russia the level of injury and unforeseen circumstances is very great. People traditionally pay little attention to formation of reserves in case of temporary or permanent incapacity for work. The main aim of the study is to consider the system of the accident insurance. Methods: the matching method required to identify the main trends in the insurance market; the analytical technique which allows understanding the typical problems for this type of insurance; the statistical method allows us to identify the extent of accident insurance. Results. The paper reveals the essence and types of accident insurance and considers the model events when the insurance company indemnifies for the damage. The causes of the demand for this type of insurance in Russia are identified. Based on the statistical data the author has determined the proportion of the accident insured people
An interdisciplinary investigation of a recent submarine mass transport deposit at the continental margin off Uruguay
Assessing frequency and extent of mass movement at continental margins is crucial to evaluate risks for offshore constructions and coastal areas. A multidisciplinary approach including geophysical, sedimentological, geotechnical, and geochemical methods was applied to investigate multistage mass transport deposits (MTDs) off Uruguay, on top of which no surficial hemipelagic drape was detected based on echosounder data. Nonsteady state pore water conditions are evidenced by a distinct gradient change in the sulfate (SO42−) profile at 2.8 m depth. A sharp sedimentological contact at 2.43 m coincides with an abrupt downward increase in shear strength from ∼10 to >20 kPa. This boundary is interpreted as a paleosurface (and top of an older MTD) that has recently been covered by a sediment package during a younger landslide event. This youngest MTD supposedly originated from an upslope position and carried its initial pore water signature downward. The kink in the SO42− profile ∼35 cm below the sedimentological and geotechnical contact indicates that bioirrigation affected the paleosurface before deposition of the youngest MTD. Based on modeling of the diffusive re‐equilibration of SO42− the age of the most recent MTD is estimated to be <30 years. The mass movement was possibly related to an earthquake in 1988 (∼70 km southwest of the core location). Probabilistic slope stability back analysis of general landslide structures in the study area reveals that slope failure initiation requires additional ground accelerations. Therefore, we consider the earthquake as a reasonable trigger if additional weakening processes (e.g., erosion by previous retrogressive failure events or excess pore pressures) preconditioned the slope for failure. Our study reveals the necessity of multidisciplinary approaches to accurately recognize and date recent slope failures in complex settings such as the investigated area
Precise Measurements of <sup>12</sup>CH<sub>2</sub>D<sub>2</sub> by Tunable Infrared Laser Direct Absorption Spectroscopy
Deep Brain Stimulation for Obesity: A Review and Future Directions
The global prevalence of obesity has been steadily increasing. Although pharmacotherapy and bariatric surgeries can be useful adjuvants in the treatment of morbid obesity, they may lose long-term effectiveness. Obesity result largely from unbalanced energy homeostasis. Palatable and densely caloric foods may affect the brain overlapped circuits involved with homeostatic hypothalamus and hedonic feeding. Deep brain stimulation (DBS) consists of delivering electrical impulses to specific brain targets to modulate a disturbed neuronal network. In selected patients, DBS has been shown to be safe and effective for movement disorders. We review all the cases reports and series of patients treated with DBS for obesity using a PubMed search and will address the following obesity-related issues: (i) the hypothalamic regulation of homeostatic feeding; (ii) the reward mesolimbic circuit and hedonic feeding; (iii) basic concepts of DBS as well as the rationale for obesity treatment; (iv) perspectives and challenges in obesity DBS. The small number of cases provides preliminary evidence for the safety and the tolerability of a potential DBS approach. The ventromedial (n = 2) and lateral (n = 8) hypothalamic nuclei targets have shown mixed and disappointing outcomes. Although nucleus accumbens (n = 7) targets were more encouraging for the outcomes of body weight reduction and behavioral control for eating, there was one suicide reported after 27 months of follow-up. The authors did not attribute the suicide to DBS therapy. The identification of optimal brain targets, appropriate programming strategies and the development of novel technologies will be important as next steps to move DBS closer to a clinical application. The identification of electrical control signals may provide an opportunity for closed-loop adaptive DBS systems to address obesity. Metabolic and hormonal sensors such as glycemic levels, leptin, and ghrelin levels are candidate control signals for DBS. Focused excitation or alternatively inhibition of regions of the hypothalamus may provide better outcomes compared to non-selective DBS. Utilization of the NA delta oscillation or other physiological markers from one or multiple regions in obesity-related brain network is a promising approach. Experienced multidisciplinary team will be critical to improve the risk-benefit ratio for this approach
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