Warm and Dry Spells (WDS) in Austral Winter over Central South America

The horizontal and vertical structure of unusually warm and dry spells (WDS) over the central parts of South America during the winter and post-winter months (JJAS) are studied. During WDS the mean temperature and humidity anomalies over central Brazil are about +4.1°C and −13.2%, respectively. The mean duration of WDS is 11 days and their mean frequency is less than one per year during the months of JJAS. Apparently, WDS have no preference for the phase of ENSO. Widespread and persistent subsidence in the middle troposphere is observed in tropical Brazil during WDS, which renders the lower tropospheric air warm and dry. The negative anomalies of the specific humidity are observed to be associated with the subsidence regions. A strong, slow moving ridge in the eastern South Pacific and a low-pressure center in northern Argentina are important surface characteristics during the WDS. A more detailed investigation of two specific WDS events, a strong event (August–September 1999) and a moderate one (June 2002), shows a blocking-like situation in the 500-hPa geopotential and surface pressure fields in the Pacific. The South Atlantic subtropical high somewhat approaches the continent. Strong northerlies over the central and eastern parts of Brazil are also observed in the lower troposphere. During WDS the regional circulation acquires summertime characteristics, except for the absence of precipitation, and the circulation in the meridional plane is in the opposite sense from the Hadley circulation. A frontal system, supported by a 500-hPa trough, advances into central Brazil, causing the dissipation of the anomalous situation

Crystallization of a scRIP-gelonin isolated from plant seeds Gelonium multiforum

Single crystals of the protein gelonin isolated from the seeds of Gelonium multiforum have been grown at room temperature by vapor diffusion method. The crystals are monclinic with a = 49.4 Å, b = 44.9 Å, c = 137.4 Å, and β = 98.3°. The space group is P21, with two molecules in the asymmetric unit which are related by a noncrystallographic 2-fold axis along ψ =13° and φ =88°. The crystals diffract X-rays to high resolution, making it possible to obtain an accurate structure of this single chain ribosome inactivating protein

Simulation and Integrated Testing of Process Models of PFBR Operator Training Simulator

AbstractHigh fidelity Full Scope Operator Training Simulators play a key role in imparting plant related knowledge to the operating personnel in an effective way. It provides a platform for training the operators on normal and emergency conditions including all types of scenarios that would arise in any Nuclear Power Plant. The scenario based training helps the plant operator to handle a crisis in an efficient manner with the ultimate goal of safe and efficient operation of the plant.This paper discusses about the general description of PFBR Operator Training Simulator, modeling and simulation of various process models, the complexities involved etc. It also covers the associated process logics, controls, display of alarms and indications, malfunctions and transient incidents related to each process model, integration with other sub systems, individual process model testing, integrated performance testing and verification and validation of models. Simulation of process models are broadly classified into two main categories namely, External Models - that are developed in-house and ported to the simulator environment and Internal Models - that are developed using Simulation Tool. External Models are tested on the desk top for intended functioning and after obtaining satisfactory results, the models are ported to the simulator base wherein the Logical and Virtual Panel Models are built to represent a real system of the plant. Internal Models are built using the Simulation Tools and integrated with the External Models after testing. Combination of External and Internal Model represents the total plant and the performance testing is conducted in an Integrated Mode to qua lify the Process Models for training purpose

Convective Boundary Layer Growth: Analytical and Numerical Approaches

The transition phase from neutral boundary layer to convectiveboundary layer (CBL) is the focus of this paper. The characteristics ofthe turbulent kinetic energy (TKE) during the growth phase of the CBLare analyzed with the help of two analytical spectral models. The TKEevolutions generated by the analytical models agree fairly well with theresults of Large Eddy Simulation for different vertical levels.A fase de transição de uma camada limite neutra para uma camadalimite convectiva (CLC) é tópico do presente artigo. As característicasda energia cinética turbulenta (ECT) durante a fase de crescimentoda CLC são analisadas com o uso de dois modelos espectrais analíticos.A evolução gerada pelos modelos analíticos concorda bem com os resultadosde simulação de grandes turbilhões para diferentes níveis verticais

A new perspective of the climatological features of upper-level cut-off lows in the Southern Hemisphere

This study presents a detailed view of the seasonal variability of upper-level cut-off lows (COLs) in the Southern Hemisphere. The COLs are identified and tracked using data from a 36-year period of the European Centre for Medium Range Weather Forecast reanalysis (ERA-Interim). The objective identification of the COLs uses a new approach, which is based on 300 hPa relative vorticity minima, and three restrictive criteria of the presence of a cold-core, stratospheric potential vorticity intrusion, and cut-off cyclonic circulation. The highest COL activity is in agreement with previous studies, located near three main continental areas (Australia, South America, and Africa), with maximum frequencies usually observed in the austral autumn. The COL mean intensity values show a marked seasonal and spatial variation, with maximum (minimum) values during the austral winter (summer), a unique feature that has not been observed previously in studies based on the geopotential. The link between intensity and lysis is examined, and finds that weaker systems are more susceptible to lysis in the vicinity of the Andes Cordillera, associated with the topographic Rossby wave. Lysis and genesis regions are close to each other, confirming that COLs are quasi-stationary systems. Also, COLs tend to move eastward and are faster over the higher latitudes. The mean growth/decay rates coincide with the major genesis and lysis density regions, such as the significant decay values across the Andes all year. As a consequence of using vorticity for the tracking method a longer lifetime of COLs is detected than in other studies, but this does not affect the total frequency of occurrence. Comparisons with other studies suggest that the differences in seasonality are due to uncertainties in the reanalyses and the methods used to identify COLs