454 research outputs found
Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal
Distinction between drought and aridity is crucial
to understand water scarcity processes. Drought indices
are used for drought identification and drought severity
characterisation. The Standardised Precipitation Index
(SPI) and the Palmer Drought Severity Index (PDSI) are the
most known drought indices. In this study, they are compared
with the modified PDSI for Mediterranean conditions
(MedPDSI) and the Standardised Precipitation Evapotranspiration
Index (SPEI). MedPDSI results from the soil water
balance of an olive crop, thus real evapotranspiration is
considered, while SPEI uses potential (climatic) evapotranspiration.
Similarly to the SPI, SPEI can be computed at
various time scales. Aiming at understanding possible impacts
of climate change, prior to compare the drought indices,
a trend analysis relative to precipitation and temperature
in 27 weather stations of Portugal was performed for the
period 1941 to 2006. A trend for temperature increase was
observed for some weather stations and trends for decreasing
precipitation in March and increasing in October were also
observed for some locations. Comparisons of the SPI and
SPEI at 9- and 12-month time scales, the PDSI and Med-
PDSI were performed for the same stations and period. SPI
and SPEI produce similar results for the same time scales
concerning drought occurrence and severity. PDSI and Med-
PDSI correlate well between them and the same happened
for SPI and SPEI. PDSI and MedPDSI identify more severe
droughts than SPI or SPEI and identify drought occurrence
earlier than these indices. This behaviour is likely to be related
with the fact that a water balance is performed with
PDSI and MedPDSI, which better approaches the supplydemand
balance
Necessidades de água e produtividade económica da rega de milho em condições de escassez
A identificação das necessidades de rega do milho, uma das principais culturas regadas em Portugal Continental,
constitui uma medida de preparação para enfrentar as secas e a escassez de água. Definiram-se várias estratégias
de rega com o objectivo de redução da procura de água de rega com impactos aceitáveis na produção. O modelo
de balanço hÃdrico e de simulação de calendários de rega SIMDualKc, anteriormente calibrado e validado para a
cultura do milho em Portugal, foi utilizado para simular as necessidades de água para condições de seca severa e
extrema. Este estudo foi realizado para milho regado por aspersão e aplicado a várias localidades: Vila Real,
Bragança e Miranda do Douro no Norte, Coimbra e Viseu no Centro, e Beja, Évora e Elvas no Sul. As
alternativas de rega foram avaliadas tendo em consideração a poupança de água de rega e o impacto nas
produções; para inferir a viabilidade económica da rega deficitária foram determinados indicadores da
produtividade fÃsica e económica da água recorrendo a dados sobre o valor da produção e desempenho de
sistemas. Os resultados mostram que as estratégias de rega deficitárias poderão ser viáveis quando os défices
hÃdricos forem muito baixos. Como alternativa poder-se-á optar pela satisfação das necessidades totais da cultura
mas diminuindo a área cultivada
EnzMetâ„¢: An Enzymatic Metallography Reagent for Accurately Delineating Neuronal Boundaries for Segmenting Gap Junction-Coupled Neurons in their Three-dimensional Space
Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201
Electrical conductivity and mineral composition of the imbibition solution of bean seeds during storage
Histological assessment of paxgene tissue fixation and stabilization reagents
Within SPIDIA, an EC FP7 project aimed to improve pre analytic procedures, the PAXgene Tissue System (PAXgene), was designed to improve tissue quality for parallel molecular and morphological analysis. Within the SPIDIA project promising results were found in both genomic and proteomic experiments with PAXgene-fixed and paraffin embedded tissue derived biomolecules. But, for this technology to be accepted for use in both clinical and basic research, it is essential that its adequacy for preserving morphology and antigenicity is validated relative to formalin fixation. It is our aim to assess the suitability of PAXgene tissue fixation for (immuno)histological methods. Normal human tissue specimens (n = 70) were collected and divided into equal parts for fixation either with formalin or PAXgene. Sections of the obtained paraffin-embedded tissue were cut and stained. Morphological aspects of PAXgene-fixed tissue were described and also scored relative to formalin-fixed tissue. Performance of PAXgene-fixed tissue in immunohistochemical and in situ hybridization assays was also assessed relative to the corresponding formalin-fixed tissues. Morphology of PAXgene-fixed paraffin embedded tissue was well preserved and deemed adequate for diagnostics in most cases. Some antigens in PAXgene-fixed and paraffin embedded sections were detectable without the need for antigen retrieval, while others were detected using standard, formalin fixation based, immunohistochemistry protocols. Comparable results were obtained with in situ hybridization and histochemical stains. Basically all assessed histological techniques were found to be applicable to PAXgene-fixed and paraffin embedded tissue. In general results obtained with PAXgene-fixed tissue are comparable to those of formalin-fixed tissue. Compromises made in morphology can be called minor compared to the advantages in the molecular pathology possibilities
Nonperturbative renormalization group approach to frustrated magnets
This article is devoted to the study of the critical properties of classical
XY and Heisenberg frustrated magnets in three dimensions. We first analyze the
experimental and numerical situations. We show that the unusual behaviors
encountered in these systems, typically nonuniversal scaling, are hardly
compatible with the hypothesis of a second order phase transition. We then
review the various perturbative and early nonperturbative approaches used to
investigate these systems. We argue that none of them provides a completely
satisfactory description of the three-dimensional critical behavior. We then
recall the principles of the nonperturbative approach - the effective average
action method - that we have used to investigate the physics of frustrated
magnets. First, we recall the treatment of the unfrustrated - O(N) - case with
this method. This allows to introduce its technical aspects. Then, we show how
this method unables to clarify most of the problems encountered in the previous
theoretical descriptions of frustrated magnets. Firstly, we get an explanation
of the long-standing mismatch between different perturbative approaches which
consists in a nonperturbative mechanism of annihilation of fixed points between
two and three dimensions. Secondly, we get a coherent picture of the physics of
frustrated magnets in qualitative and (semi-) quantitative agreement with the
numerical and experimental results. The central feature that emerges from our
approach is the existence of scaling behaviors without fixed or pseudo-fixed
point and that relies on a slowing-down of the renormalization group flow in a
whole region in the coupling constants space. This phenomenon allows to explain
the occurence of generic weak first order behaviors and to understand the
absence of universality in the critical behavior of frustrated magnets.Comment: 58 pages, 15 PS figure
Body condition score, weight variation and reproductive performance of beef cows in rangelands from the Pantanal region
Objetivou-se avaliar a influência do escore de condição corporal (ECC) sobre a eficiência reprodutiva de vacas de cria nos perÃodos pré e pós-parto e a probabilidade de parição, usando o escore de condição corporal e a variação ponderal no perÃodo crÃtico do ciclo reprodutivo. Utilizaram-se 248 vacas multÃparas mantidas em pastagens nativas distribuÃdas em quatro estratégias de suplementação: mistura mineral (controle); suplemento farelado; suplemento lÃquido; suplemento lÃquido para vacas e bezerros. As avaliações de peso e ECC, na escala de 1 a 9, foram realizadas no perÃodo crÃtico: em agosto (perÃodo pré-parto, 60-90 dias antes da parição) e em janeiro (perÃodo pós-parto e reprodutivo) durante quatro anos consecutivos. Para a análise dos anos consecutivos de reprodução, criou-se um escore de reprodução, ou seja, somou-se o número de parições de cada vaca durante os quatro anos pecuários avaliados. O escore de condição corporal nos perÃodos pré e pós-parto e a idade da vaca influenciaram o escore de reprodução. Portanto, para avaliação da probabilidade de parição, foram utilizadas todas as vacas, classificadas em paridas e vazias. Utilizando equações de estimação generalizadas (EEG), foi modelada a probabilidade de as matrizes serem classificadas como paridas considerando variáveis exploratórias ao longo do tempo. Para se obter probabilidade de parição superior a 80%, as vacas devem possuir escore de aproximadamente 5,5 no perÃodo pré-parto. Aproximadamente 60% das vacas paridas mantiveram ou ganharam peso no perÃodo crÃtico do ano, o que levou a maior probabilidade de reconcepção, similar ao observado para as vacas vazias, porém com probabilidade menor de parição. O perÃodo pré-parto é o melhor para estimar a probabilidade de parição das vacas por meio da avaliação do escore corporal. A seleção de vacas adaptadas à s condições bioclimáticas do Pantanal aumenta a probabilidade de produção de um bezerro por vaca por ano. _________________________________________________________________________________ ABSTRACTThe aim of this study was to evaluate the influence of body condition score (BCS) on reproductive performance of beef cows before and after calving and to evaluate the calving probability using body condition score and weight variation during critical periods of the cow reproductive cycle. From 2001 to 2005, the body condition score was recorded in 248 multiparous cows raised in native pastures, submitted to different supplementation treatments (mineral mixture only - control; dry supplement; liquid supplement and liquid supplement for cow and calves). Weighing and body condition evaluation were made on a 1-9 point scale in August (prepartum period, 60-90 days before parturition) and January (postpartum and reproductive period). A reproduction score was created in function of the body scores in four consecutive years. Except for the treatment, the other factors (body condition score in the prepartum and postpartum periods and cow age) influenced the reproduction score. Thus, the calving probabilities were estimated for all cows. Generalized estimating equations (GEE) were used to evaluate the calving probability in function of the exploratory variables over time. Calving probability higher than 80% was obtained when cows scored 5,5 before calving. In relation to weight, the results showed that about 60% of calving cows maintained or gained weight in the postpartum period, leading to increase in the rebreeding probability. Similar situation occurred with single cows; however, the calving probability was lower. These results indicate that the calving probability using BCS is better estimated before calving. Furthermore, it indicates the presence of cows more adapted to the Pantanal climatic and feeding conditions than others
The design and evaluation of travelling gun irrigation systems: enrolador software
Technical Paperinfo:eu-repo/semantics/publishedVersio
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