3,641 research outputs found
Plastic molds reduce cost of encapsulating electric cable connectors
Resin casting of the aluminum master pattern forms a plastic mold for encapsulating a cable connector. An elastomer is injected into the mold and cured. The mold is disassembled leaving an elastomeric encapsulation around the connector
Field collection and preservation of urine in orangutans and chimpanzees
Poster presented at the American Association of Physical Anthropologists Meeting, Durham, North Carolina, April 14, 1996Disease is recognized as a critical factor that can affect primate behavior, yet few methods allow
for the quantification of disease states in wild primates. This paper reports on the use of urinary
test strips to detect the presence of disease and monitor physiological status in wild orangutans .
Urine was collected from wild orangutans at Gunung Palung National Park, Indonesian Borneo,
between August 1994 and August 1995. A total of 387 urine samples were obtained from over 43
orangutans by placing plastic sheets beneath individuals during urination. Boehringer Mannheim
urinary test strips were used to evaluate specific gravity, leukocytes, nitrite, pH, ketones, protein,
glucose, urobilinogen, bilirubin and blood . Objectives of using these test strips were (1) to
evaluate the presence of disease (2) to detect signs of nutritional stress (3) to monitor the
occurrence of menstruation and (4) to use specific gravity as a measure of urine concentration for
hormonal analysis. [TRUNCATED
Recommended from our members
The Effect of Limited Attention and Delay on Negative Arousing False Memories
Previous research has shown that, in comparison to neutral stimuli, false memories for high arousing negative stimuli are greater after very fast presentation and limited attention at study. However, full compared to limited attention conditions still produce comparably more false memories for all stimuli types. Research has also shown that emotional stimuli benefit from a period of consolidation. What effect would such consolidation have on false memory formation even when attention is limited at study? The aim of the present study was to investigate the effect of fast presentation on false memory production for negatively-arousing and neutral items over time using the DRM paradigm. Sixty-Eight participants studied Negative and neutral DRM lists with fast or slow presentation conditions. Half completed a recognition test immediately and half completed a recognition test after one-week. Results revealed that, for fast presentation, negative critical lures increased after one week and were comparable to negative critical lures in the slow presentation encoding conditions. Neutral critical lures in the fast presentation condition did not change and remained lower compared to the slow presentation condition. These findings are the first demonstration that arousing negative false memories can increase over time when attention at encoding is limited
A performance analysis of the PASLIB version 2.1X SEND and RECV routines on the finite element machine
The Finite Element Machine is an experimental array processor designed to support research in parallel algorithms and architectures. This report presents a case study of communications using the SENDa and RECV system software routines on the Finite Element Machine, followed by a discussion of the effect of I/O performance on the efficiency of parallel algorithms
System software for the finite element machine
The Finite Element Machine is an experimental parallel computer developed at Langley Research Center to investigate the application of concurrent processing to structural engineering analysis. This report describes system-level software which has been developed to facilitate use of the machine by applications researchers. The overall software design is outlined, and several important parallel processing issues are discussed in detail, including processor management, communication, synchronization, and input/output. Based on experience using the system, the hardware architecture and software design are critiqued, and areas for further work are suggested
Are male orangutans a threat to infants? Evidence of mother-offspring counter strategies to infanticide in Bornean orangutans (Pongo pygmaeus wurmbii)
Sexually selected infanticide by males is widespread in primates. Female primates employ a variety of strategies to reduce infanticide risk. While infanticide has never been directly observed in wild orangutans (Pongo spp.), their slow life history makes infants vulnerable to infanticide. The mating strategies of female orangutans include polyandrous and postconceptive mating that may serve to increase paternity confusion, an infanticide avoidance strategy. Here, we investigate whether female orangutans alter their social interactions with males as another infanticide avoidance strategy. We hypothesize that females with younger offspring avoid males and that the distance between mother and offspring decreases in the presence of males. We use long-term behavioral data collected between 1994 and 2016 from Bornean orangutans (Pongo pygmaeus wurmbii) in Gunung Palung National Park, Indonesia, to test whether the sexual selection hypothesis for infanticide helps explain aspects of orangutan social behavior. We found that mothers with offspring 6 yr. old and females without offspring. In addition, the distance between a motherâoffspring dyad showed a statistically significant decrease in the presence of males, but not females. Our results are consistent with the hypothesis that female orangutans employ strategies to reduce infanticide risk in their social interactions. Because orangutans have a high fissionâfusion dynamic, they have flexibility in manipulating social interactions as a counter-infanticide strategy. Our results suggest that infanticide by males is a selective pressure shaping female orangutan social behavior.Accepted manuscrip
Myocardial perfusion in heart disease
Heart disease: Coronary heart disease is a major cause of mortality and morbidity in the UK and globally. It is managed with medical therapy and coronary revascularisation to reduce symptoms and reduce risk of major adverse cardiovascular events. When patients present with chest pain, it is important to risk stratify those that would most benefit from invasive coronary assessment and those that can be managed with medical therapy alone. Myocardial perfusion techniques have been developed in order to do this.
Cardiovascular magnetic resonance (CMR) with stress perfusion: CMR allows the non-invasive assessment of coronary artery disease (CAD). Under conditions of vasodilator stress, a gadolinium based contrast agent is injected and during the first pass through the left ventricle, perfusion defects can be observed. There is a strong evidence base for perfusion CMR but the technique is qualitative, relies on experienced operators and potentially misses globally low perfusion such as in cases of âbalancedâ ischaemia.
Quantitative perfusion CMR: In contrast, quantitative perfusion techniques allow the calculation of myocardial blood flow (MBF). It is more objective, less reliant on the expert observer and can give additional insights into microvascular disease and cardiomyopathy. As well as being less subjective, quantitative perfusion has other advantages for example it allows full assessment of ischaemic burden and may contain prognostic information that could be used to risk stratify and improve patient care. However, quantitative perfusion has been outside the realm of routine clinical practice due to difficulties in acquiring suitable data for full quantification and the laborious nature of analysing it.
Perfusion mapping: Peter Kellman, Hui Xue and colleagues at the National Institutes for Health, USA developed the âperfusion mappingâ technique to address these limitations. Perfusion maps are generated automatically and inline during the CMR scan and each voxel encodes myocardial blood flow. This allows the instant quantification of MBF without complex acquisition techniques and post processing. In this thesis I have taken perfusion mapping and deployed in the real-world at a scale an order of magnitude higher than prior quantitative perfusion studies, developing the evidence base for routine clinical use across a broad range of diseases and scenarios:
In coronary artery disease: I have shown that perfusion mapping is accurate to detect coronary artery stenosis as defined by 3D quantitative coronary angiography in a single centre, 50 patient study. Transmural and subendocardial perfusion are particularly sensitive to detect coronary stenoses with performances similar to expert readers. There is a high sensitivity and high negative predictive value making perfusion mapping a good ârule-outâ test for coronary disease.
Quantitative perfusion and prognosis: I investigated whether stress MBF and myocardial perfusion reserve (MPR) calculated by perfusion mapping would encode prognostic information in a 1049 patient multi-centre study over a mean follow up time of 605 days. Both stress MBF and MPR were independently associated with death and major adverse cardiovascular events (MACE). The hazard ratio for MACE was 2.14 for each 1ml/g/min decrease in stress MBF and 1.74 for each unit decrease in MPR. This work can now be taken forward with prospective studies in order to better risk stratify patients, including those without perfusion defects on clinical read.
Reference ranges and non-obstructive coronary disease: I sought to determine the factors that contribute to perfusion in a multi-centre registry study. In patients with no obstructive coronary artery disease, stress MBF was reduced with age, diabetes, left ventricular hypertrophy (LVH) and the use of beta blockers. Rest MBF was influenced by sex (higher in females) and reduced with beta blockers. This study suggests patient factors beyond coronary artery disease (and therefore likely microvascular disease) should also be considered when interpreting quantitative perfusion studies.
In cardiomyopathy: I also investigated myocardial perfusion in cardiomyopathy looking at Fabry disease as an example disease. In a prospective, observational, single centre study of 44 patients and 27 controls I found Fabry patients had reduced perfusion (and therefore likely microvascular dysfunction), particularly in the subendocardium and was associated with left ventricular hypertrophy (LVH), glycophospholipid storage and scar. Perfusion was reduced even in patients without LVH suggesting it is an early disease marker.
In conclusion, in this thesis, I have developed an evidence base for quantitative perfusion CMR and demonstrated how it can be integrated into routine clinical care. Perfusion mapping is accurate for detecting coronary artery stenosis and encodes prognostic information. Further work in this area could enable patients to be risk stratified based on their myocardial perfusion in order to reduce the morbidity and mortality associated with epicardial and microvascular coronary artery disease. Following on from this work, two further British Heart Foundation Clinical Research Training Fellowships have been awarded to further investigate quantitative perfusion in patients following surgical revascularisation of coronary disease and in patients with hypertrophic cardiomyopathy
Recommended from our members
The role of attention at retrieval on the false recognition of negative emotional DRM lists
This study examined the role of attention at retrieval on the false recognition of emotional items using the DeeseâRoedigerâMcDermott (DRM) paradigm. Previous research has shown that divided attention at test increases false remember judgements for neutral critical lures. However, no research has yet directly assessed emotional false memories when attention is manipulated at retrieval. To examine this, participants studied negative (low in valence and high in arousal) and neutral DRM lists and completed recognition tests under conditions of full and divided attention. Results revealed that divided attention at retrieval increased false remember judgements for all critical lures compared to retrieval under full attention, but in both retrieval conditions, false memories were greater for negative compared to neutral stimuli. We believe that this is due to reliance on a more easily accessible (meaning of the word) but less diagnostic form of source monitoring, amplified under conditions of divided attention
Estimation of linkage disequilibrium in a sample of the United Kingdom dairy cattle population using unphased genotypes
The association between genetic marker alleles was estimated for two regions of the bovine genome from a random sample of 50 young dairy bulls born in the United Kingdom between 1988 and 1995. Microsatellite marker genotypes were obtained for six markers on chromosome 2 and seven markers on chromosome 6, spanning 38 and 20 cM, respectively. Two different methods, which do not require family information, were used to estimate population haplotype frequencies. Haplotype frequencies were estimated for pairs of loci using the expectation-maximization algorithm and for all linked loci using a Bayesian approach via a Markov chain-Monte Carlo algorithm. Significant (P = 0.0007) linkage disequilibrium was detected between pairs of loci in syntenic groups (that is, loci in the same linkage group), extending to about 10 cM. No significant linkage disequilibrium was detected between markers in nonsyntenic regions. Given the observed level of linkage disequilibrium, mapping methods based on population-wide association might provide a better resolution than traditional quantitative trait loci mapping methods in the U.K. dairy cattle population and may reduce the required sample sizes of the experiments
- âŠ