464 research outputs found
Temperature inversion symmetry in the Casimir effect with an antiperiodic boundary condition
We present explicitly another example of a temperature inversion symmetry in
the Casimir effect for a nonsymmetric boundary condition. We also give an
interpretation for our result.Comment: 4 page
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
Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip
The ATLAS Collaboration will upgrade its semiconductor pixel tracking
detector with a new Insertable B-layer (IBL) between the existing pixel
detector and the vacuum pipe of the Large Hadron Collider. The extreme
operating conditions at this location have necessitated the development of new
radiation hard pixel sensor technologies and a new front-end readout chip,
called the FE-I4. Planar pixel sensors and 3D pixel sensors have been
investigated to equip this new pixel layer, and prototype modules using the
FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN
SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test
results are presented, including charge collection efficiency, tracking
efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
STENOSTOMUM LEUCOPS DUGÈS, 1828 (PLATYHELMINTHES, CATENULIDA): A PUTATIVE SPECIES COMPLEX WITH PHENOTYPIC PLASTICITY
RESUMO Stenostomum são pequenos vermes que vivem em água doce e normalmente se reproduzem assexualmente por paratomia. Eles estão na base da filogenia dos platelmintes. Por mais de um século, espécies desse gênero, especialmente S. leucops, vêm sendo empregadas em estudos biológicos, principalmente sobre regeneração. Entretanto, alguns aspectos básicos da biologia destes vermes são ainda pobremente conhecidos. Neste estudo, caracterizamos uma linhagem que vem sendo mantida no laboratório por cinco anos. O tempo necessário para reprodução assexuada e completa formação de zoóides, a 28°C, é de aproximadamente 42,5 horas. O número de células nos zoóides, logo após a paratomia, é de aproximadamente 2.500. O número de zoóides presentes nos vermes é uma característica variável e depende das condições de cultivo. Em alguns procedimentos de cultivo de S. leucops, apenas cadeias com dois zoóides são formadas. No entanto, em outras condições de cultivo, cadeias de até cinco zoóides podem ser observadas. Análise filogenética empregando sequência do gene de Citocromo C Oxidase (COI) mostrou que S. leucops e S. grande constituem um complexo de espécies cujas linhagens mostram altas divergências intraespecíficas.ABSTRACT Species of Stenostomum are small flatworms that live in freshwater and normally reproduce asexually by paratomy. They are basal in the phylogeny of Platyhelminthes. For more than a century, species of this genus, especially S. leucops, have been used in regeneration and other biological studies. However, some basic aspects of their biology are poorly known. Here, we characterized a strain of S. leucops that has been maintained in the laboratory for five years and a recent strain of S. grande. The time required for complete formation of zooids of S. leucops by asexual reproduction is approximately 42.5 hours at 28°C. The number of cells in the zooids, soon after paratomy, is approximately 2,500. The number of zooids formed in the chain is a plastic characteristic and is dependent on the conditions for cultivation. In some cultivation conditions of S. leucops, only worms with two zooids are formed. However, in other conditions, worms with up to five zooids are observed. Phylogenetic analyses of a fragment of the Cytochrome C Oxidase I (COI) sequence showed S. leucops and S. grande species constitute a species complex, the lineages of which having high intraspecific divergences
Functional mechanisms underlying pleiotropic risk alleles at the 19p13.1 breast-ovarian cancer susceptibility locus
A locus at 19p13 is associated with breast cancer (BC) and ovarian cancer (OC) risk. Here we analyse 438 SNPs in this region in 46,451 BC and 15,438 OC cases, 15,252 BRCA1 mutation carriers and 73,444 controls and identify 13 candidate causal SNPs associated with serous OC (P=9.2 × 10-20), ER-negative BC (P=1.1 × 10-13), BRCA1-associated BC (P=7.7 × 10-16) and triple negative BC (P-diff=2 × 10-5). Genotype-gene expression associations are identified for candidate target genes ANKLE1 (P=2 × 10-3) and ABHD8 (P<2 × 10-3). Chromosome conformation capture identifies interactions between four candidate SNPs and ABHD8, and luciferase assays indicate six risk alleles increased transactivation of the ADHD8 promoter. Targeted deletion of a region containing risk SNP rs56069439 in a putative enhancer induces ANKLE1 downregulation; and mRNA stability assays indicate functional effects for an ANKLE1 3′-UTR SNP. Altogether, these data suggest that multiple SNPs at 19p13 regulate ABHD8 and perhaps ANKLE1 expression, and indicate common mechanisms underlying breast and ovarian cancer risk
Estimación de las necessidades hídricas de la papaya utilizando la aproximación de los coeficientes culturales duales
The use of irrigation in the cultivation of papaya is increasing in recent years. Thus, there is the need for
improved knowledge of the most appropriate irrigation scheduling practices to be adopted as well as the more
adequate estimation of crop water requirements. With this objective, the simulation model SIMDualKc was
adopted and calibrated. The model performs the calculation of crop evapotranspiration (ETc) with the
methodology of the dual crop coefficient (Kc = Kcb + Ke), i.e., using a basal crop coefficient to estimate crop
transpiration and an evaporation coefficient to estimation soil water evaporation. The research was conducted at
the Experimental Station of Irrigation and Drainage, located in Alquízar, Havana, Cuba. The experiments were
carried out between March and November 1997 with the papaya var. "Maradol red". The calibration consisted in
searching the crop factors relative to the different stages of crop development that minimize the differences
between the simulated and observed soil moisture content. Various goodness of fit indicators were used to
evaluate the model predictions. It can be concluded that the model was properly calibrated and can be used to
generate alternative irrigation schedules that improve water use and productivity of papaya in the considered soil
and climate condition
- …
