876 research outputs found
Neutrinos from beta processes in a presupernova: probing the isotopic evolution of a massive star
We present a new calculation of the neutrino flux received at Earth from a
massive star in the hours of evolution prior to its explosion as a
supernova (presupernova). Using the stellar evolution code MESA, the neutrino
emissivity in each flavor is calculated at many radial zones and time steps. In
addition to thermal processes, neutrino production via beta processes is
modeled in detail, using a network of 204 isotopes. We find that the total
produced flux has a high energy spectrum tail, at
MeV, which is mostly due to decay and electron capture on isotopes with . In a tentative window of observability of MeV and hours pre-collapse, the contribution of beta processes to the flux
is at the level of . For a star at kpc distance, a 17 kt
liquid scintillator detector would typically observe several tens of events
from a presupernova, of which up to due to beta processes. These
processes dominate the signal at a liquid argon detector, thus greatly
enhancing its sensitivity to a presupernova.Comment: 14 pages, 5 figure
Contralateral Total Hip Arthroplasty After Hindquarter Amputation
We describe the management and outcome of a 62-year old lady who developed severe osteoarthritis of the hip, nine years after a hindquarter amputation for radiation-induced sarcoma of the contralateral pelvis. The difficulties of stabilising the pelvis intraoperatively and the problems of postoperative rehabilitation are outlined. The operation successfully relieved her pain and restored limited mobility
Temporal pattern of africanization in a feral honeybee population from Texas inferred from mitochondrial DNA
The invasion of Africanized honeybees (Apis mellifera L.) in the Americas provides a window of opportunity
to study the dynamics of secondary contact of subspecies of bees that evolved in allopatry in ecologically distinctive
habitats of the Old World. We report here the results of an 11-year mitochondrial DNA survey of a feral honeybee
population from southern United States (Texas). The mitochondrial haplotype (mitotype) frequencies changed radically
during the 11-year study period. Prior to immigration of Africanized honeybees, the resident population was essentially
of eastern and western European maternal ancestry. Three years after detection of the first Africanized swarm there
was a mitotype turnover in the population from predominantly eastern European to predominantly A. m. scutellata
(ancestor of Africanized honeybees). This remarkable change in the mitotype composition coincided with arrival of
the parasitic mite Varroa destructor, which was likely responsible for severe losses experienced by colonies of European
ancestry. From 1997 onward the population stabilized with most colonies of A. m. scutellata maternal origin.PRODEP II - Medida 5/Acção 5.
An efficient semiparametric maxima estimator of the extremal index
The extremal index , a measure of the degree of local dependence in
the extremes of a stationary process, plays an important role in extreme value
analyses. We estimate semiparametrically, using the relationship
between the distribution of block maxima and the marginal distribution of a
process to define a semiparametric model. We show that these semiparametric
estimators are simpler and substantially more efficient than their parametric
counterparts. We seek to improve efficiency further using maxima over sliding
blocks. A simulation study shows that the semiparametric estimators are
competitive with the leading estimators. An application to sea-surge heights
combines inferences about with a standard extreme value analysis of
block maxima to estimate marginal quantiles.Comment: 17 pages, 7 figures. Minor edits made to version 1 prior to journal
publication. The final publication is available at Springer via
http://dx.doi.org/10.1007/s10687-015-0221-
A theory-grounded framework of Open Source Software adoption in SMEs
This is a post-peer-review, pre-copyedit version of an article published in European Journal of Information Systems. The definitive publisher-authenticated version Macredie, RD and Mijinyawa, K (2011), "A theory-grounded framework of Open Source Software adoption in SMEs", European Journal of Informations Systems, 20(2), 237-250 is available online at: http://www.palgrave-journals.com/ejis/journal/v20/n2/abs/ejis201060a.html.The increasing popularity and use of Open Source Software (OSS) has led to significant interest from research communities and enterprise practitioners, notably in the small business sector where this type of software offers particular benefits given the financial and human capital constraints faced. However, there has been little focus on developing valid frameworks that enable critical evaluation and common understanding of factors influencing OSS adoption. This paper seeks to address this shortcoming by presenting a theory-grounded framework for exploring these factors and explaining their influence on OSS adoption, with the context of study being small- to medium-sized Information Technology (IT) businesses in the U.K. The framework has implications for this type of business – and, we will suggest, more widely – as a frame of reference for understanding, and as tool for evaluating benefits and challenges in, OSS adoption. It also offers researchers a structured way of investigating adoption issues and a base from which to develop models of OSS adoption. The study reported in this paper used the Decomposed Theory of Planned Behaviour (DTPB) as a basis for the research propositions, with the aim of: (i) developing a framework of empirical factors that influence OSS adoption; and (ii) appraising it through case study evaluation with 10 U.K. Small- to medium-sized enterprises in the IT sector. The demonstration of the capabilities of the framework suggests that it is able to provide a reliable explanation of the complex and subjective factors that influence attitudes, subjective norms and control over the use of OSS. The paper further argues that the DTPB proved useful in this research area and that it can provide a variety of situation-specific insights related to factors that influence the adoption of OSS
Identification of africanized honey bee (Hymenoptera: apidae) mitochondrial DNA: validation of a rapid polymerase chain reaction-based assay
Polymerase chain reaction (PCR)-ampliÞed mitochondrialDNA(mtDNA)assays have
been used in studies of the Africanization process in neotropical feral and managed honey bee
populations. The approach has been adopted, in conjunction with morphometric analysis, to identify
Africanized bees for regulatory purposes in the United States such as in California. In this study, 211
Old World colonies, representing all known introduced subspecies in the United States, and 451
colonies from non-Africanized areas of the southern United States were screened to validate a rapid
PCR-based assay for identiÞcation of Africanized honey bee mtDNA. This PCR-based assay requires
a single enzyme digestion (BglII) of a single PCR-ampliÞed segment of the cytochrome b gene. The
BglII polymorphism discriminates the mitochondrial haplotype (mitotype) of Apis mellifera scutellata
L. (ancestor of Africanized bees) from that of A. m. mellifera, A. m. caucasia, A. m. ligustica, A. m.
carnica, A. m. lamarcki, A. m. cypria, A. m. syriaca, and some A. m. iberiensis, but not from that of
A. m. intermissa and some A. m. iberiensis. Nonetheless, given the very low frequency ( 1%) of African
non-A. m. scutellata mitotype present before arrival of Africanized bees in the United States, cytochrome
b/BglII assay can be used to identify maternally Africanized bees with a high degree of
reliability
- …