5,244 research outputs found
Critical components for novel direct cardiac compression device
According to the American Heart Association, there are currently 5 million
Americans diagnosed with congestive heart failure and that number is steadily increasing
(AHA, 2003). The alarming problem of congestive heart failure and other related
medical complications has created a need for devices that not only assist the heart but
also help the heart to grow and remodel back to its normal configuration. Currently,
there are several direct cardiac compression devices (DCCDs) that do assist the heart,
however, they do not help the heart to grow and remodel correctly. Dr. John C.
Criscione of Texas A&M University has proposed a novel DCCD, in which the
compression of the device reinforces the natural curvature of the heart, helping it to grow
and remodel correctly. It is hypothesized that with the support of the device, the cells of
the heart will be stimulated to grow and remodel back to their normal size and return to
their proper function. Two key components necessary to the novel DCCD were designed
and constructed for this study. The first component was an adjustable outer shell which
enabled the device to become smaller as the failing heart returned to normal size. The
second component was an inflatable inner membrane that applies direct pressure to the
outer wall of the heart in a way that promotes physiological stress and strain patterns
Investigating whether adverse prenatal and perinatal events are associated with non-clinical psychotic symptoms at age 12 years in the ALSPAC birth cohort
Background. Non-clinical psychosis-like symptoms (PLIKS) occur in about 15% of the population. It is not clear
whether adverse events during early development alter the risk of developing PLIKS. We aimed to examine whether
maternal infection, diabetes or pre-eclampsia during pregnancy, gestational age, perinatal cardiopulmonary resuscitation
or 5-min Apgar score were associated with development of psychotic symptoms during early adolescence.
Method. A longitudinal study of 6356 12-year-old adolescents who completed a semi-structured interview for
psychotic symptoms in the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. Prenatal and
perinatal data were obtained from obstetric records and maternal questionnaires completed during pregnancy.
Results. The presence of definite psychotic symptoms was associated with maternal infection during pregnancy
[adjusted odds ratio (OR) 1.44, 95% confidence interval (CI) 1.11–1.86, p=0.006], maternal diabetes (adjusted OR 3.43,
95% CI 1.14–10.36, p=0.029), need for resuscitation (adjusted OR 1.50, 95% CI 0.97–2.31, p=0.065) and 5-min Apgar
score (adjusted OR per unit decrease 1.30, 95% CI 1.12–1.50, p<0.001). None of these associations were mediated by
childhood IQ score. Most associations persisted, but were less strong, when including suspected symptoms as part of
the outcome. There was no association between PLIKS and gestational age or pre-eclampsia.
Conclusions. Adverse events during early development may lead to an increased risk of developing PLIKS.
Although the status of PLIKS in relation to clinical disorders such as schizophrenia is not clear, the similarity
between these results and findings reported for schizophrenia indicates that future studies of PLIKS may help us to
understand how psychotic experiences and clinical disorders develop throughout the life-course
Yang-Mills Inspired Solutions for General Relativity
Several exact, cylindrically symmetric solutions to Einstein's vacuum
equations are given. These solutions were found using the connection between
Yang-Mills theory and general relativity. Taking known solutions of the
Yang-Mills equations (e.g. the topological BPS monopole solutions) it is
possible to construct exact solutions to the general relativistic field
equations. Although the general relativistic solutions were found starting from
known solutions of Yang-Mills theory they have different physical
characteristics.Comment: 13 pages LaTe
A deconvolution map-making method for experiments with circular scanning strategies
Aims. To investigate the performance of a deconvolution map-making algorithm
for an experiment with a circular scanning strategy, specifically in this case
for the analysis of Planck data, and to quantify the effects of making maps
using simplified approximations to the true beams. Methods. We present an
implementation of a map-making algorithm which allows the combined treatment of
temperature and polarisation data, and removal of instrumental effects, such as
detector time constants and finite sampling intervals, as well as the
deconvolution of arbitrarily complex beams from the maps. This method may be
applied to any experiment with a circular scanning-strategy. Results.
Low-resolution experiments were used to demonstrate the ability of this method
to remove the effects of arbitrary beams from the maps and to demonstrate the
effects on the maps of ignoring beam asymmetries. Additionally, results are
presented of an analysis of a realistic full-scale simulated data-set for the
Planck LFI 30 GHz channel. Conclusions. Our method successfully removes the
effects of the beams from the maps, and although it is computationally
expensive, the analysis of the Planck LFI data should be feasible with this
approach.Comment: 14 pages, 14 figures, accepte
Increasing human dominance of tropical forests
Tropical forests house over half of Earth’s biodiversity and are an important influence on the climate system. These forests are experiencing escalating human influence, altering their health and the provision of important ecosystem functions and services. Impacts started with hunting and millennia-old megafaunal extinctions (Phase I), continuing via low-intensity shifting cultivation (Phase II), to today’s global integration (Phase III), dominated by intensive permanent agriculture, industrial logging, and attendant fires and fragmentation. Such ongoing pressures together with an intensification of global environmental change may severely degrade forests in the future (Phase IV, global simplification) unless new ‘development without destruction’ pathways are established alongside climate change resilient landscape designs
Bioinformatic characterisation of the effector repertoire of the strawberry pathogen Phytophthora cactorum
The oomycete pathogen Phytophthora cactorum causes crown rot, a major disease of cultivated strawberry. We report the draft genome of P. cactorum isolate 10300, isolated from symptomatic Fragaria x ananassa tissue. Our analysis revealed that there are a large number of genes encoding putative secreted effectors in the genome, including nearly 200 RxLR domain containing effectors, 77 Crinklers (CRN) grouped into 38 families, and numerous apoplastic effectors, such as phytotoxins (PcF proteins) and necrosis inducing proteins. As in other Phytophthora species, the genomic environment of many RxLR and CRN genes differed from core eukaryotic genes, a hallmark of the two-speed genome. We found genes homologous to known Phytophthora infestans avirulence genes including Avr1, Avr3b, Avr4, Avrblb1 and AvrSmira2 indicating effector sequence conservation between Phytophthora species of clade 1a and clade 1c. The reported P. cactorum genome sequence and associated annotations represent a comprehensive resource for avirulence gene discovery in other Phytophthora species from clade 1 and, will facilitate effector informed breeding strategies in other crops
Transnational social capital: the socio‐spatialities of civil society
Civil society remains a contested concept, but one that is widely embedded in global development processes. Transnationalism within civil society scholarship is often described dichotomously, either through hierarchical dependency relations or as a more amorphous networked global civil society. These two contrasting spatial imaginaries produce very particular ideas about how transnational relations contribute to civil society. Drawing on empirical material from research with civil society organizations in Barbados and Grenada, in this article I contend that civil society groups use forms of transnational social capital in their work. This does not, however, resonate with the horizontal relations associated with grassroots globalization or vertical chains of dependence. These social relations are imbued with power and agency and are entangled in situated historical, geographical and personal contexts. I conclude that the diverse transnational social relations that are part of civil society activity offer hope and possibilities for continued civil society action in these unexpected spatial arrangements
Live to cheat another day: bacterial dormancy facilitates the social exploitation of beta-lactamases
The breakdown of antibiotics by β-lactamases may be cooperative, since resistant cells can detoxify their environment and facilitate the growth of susceptible neighbours. However, previous studies of this phenomenon have used artificial bacterial vectors or engineered bacteria to increase the secretion of β-lactamases from cells. Here, we investigated whether a broad-spectrum β-lactamase gene carried by a naturally occurring plasmid (pCT) is cooperative under a range of conditions. In ordinary batch culture on solid media, there was little or no evidence that resistant bacteria could protect susceptible cells from ampicillin, although resistant colonies could locally detoxify this growth medium. However, when susceptible cells were inoculated at high densities, late-appearing phenotypically susceptible bacteria grew in the vicinity of resistant colonies. We infer that persisters, cells that have survived antibiotics by undergoing a period of dormancy, founded these satellite colonies. The number of persister colonies was positively correlated with the density of resistant colonies and increased as antibiotic concentrations decreased. We argue that detoxification can be cooperative under a limited range of conditions: if the toxins are bacteriostatic rather than bacteridical; or if susceptible cells invade communities after resistant bacteria; or if dormancy allows susceptible cells to avoid bactericides. Resistance and tolerance were previously thought to be independent solutions for surviving antibiotics. Here, we show that these are interacting strategies: the presence of bacteria adopting one solution can have substantial effects on the fitness of their neighbours
Acceleration-based friction coefficient estimation of a rail vehicle using feedforward NN: validation with track measurements
Low friction can lead to poor adhesion conditions between the rail and wheel, which is detrimental to rail vehicle operation and safety. Up to date knowledge of the rail-wheel friction level is currently not available across rail networks, meaning planning mitigation strategies is difficult. This paper presents a real-time friction coefficient estimation algorithm based on a feed-forward neural network (FNN). Unlike conventional methods, the FNN does not depend on slip/adhesion curves or creep force models, and only requires wheelset longitudinal acceleration and speed. The wheelset acceleration and friction measurements are obtained by running a two-car rail vehicle on a friction-modified track with five different levels of friction conditions at four different vehicle speeds. Four different FNNs are trained for four speed conditions, and their estimation performance were validated by training multiple FNNs and testing them in each speed case using new sets of data. Validation results show that the average mean absolute errors from the four FNNs remains below 0.0083
The politics of the teaching of reading
Historically, political debates have broken out over how to teach reading in primary schools and infant classrooms. These debates and “reading wars” have often resulted from public concerns and media reportage of a fall in reading standards. They also reflect the importance placed on learning to read by parents, teachers, employers, and politicians. Public and media-driven controversies over the teaching of reading have resulted in intense public and professional debates over which specific methods and materials to use with beginning readers and with children who have reading difficulties. Recently, such debates have led to a renewed emphasis on reading proficiency and “standardized” approaches to teaching reading and engaging with literacy. The universal acceptance of the importance of learning to read has also led to vested interests in specific methods, reading programmes, and early literacy assessments amongst professional, business, commercial, and parental lobbying groups. This article traces these debates and the resulting growing support for a quantitative reductionist approach to early-reading programmes
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