286 research outputs found
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Independent living programs and foster youth perceptions
The purpose of this study was to conduct a descriptive and exploratory analysis of Riverside County\u27s Independent Living Skills Program (ILSP) and its ability to prepare foster youth for successful adult transition. A vital component of this study was the exploration of perceived preparedness through the eyes of the participants enrolled in this program
Performance analysis of GA and PBIL variants for real-world location-allocation problems.
The Uncapacitated Location-Allocation problem (ULAP) is a major optimisation problem concerning the determination of the optimal location of facilities and the allocation of demand to them. In this paper, we present two novel problem variants of Non-Linear ULAP motivated by a real-world problem from the telecommunication industry: Uncapacitated Location-Allocation Resilience problem (ULARP) and Uncapacitated Location-Allocation Resilience problem with Restrictions (ULARPR). Problem sizes ranging from 16 to 100 facilities by 50 to 10000 demand points are considered. To solve the problems, we explore the components and configurations of four Genetic Algorithms [1], [2], [3] and [4] selected from the ULAP literature. We aim to understand the contribution each choice makes to the GA performance and so hope to design an Optimal GA configuration for the novel problems.We also conduct comparative experiments with Population-Based Incremental Learning (PBIL) Algorithm on ULAP. We show the effectiveness of PBIL and GA with parameter set: random and heuristic initialisation, tournament and fined grained tournament selection, uniform crossover and bitflip mutation in solving the proposed problems
Racing strategy for the dynamic-customer location-allocation problem.
In previous work, we proposed and studied a new dynamic formulation of the Location-allocation (LA) problem called the Dynamic-Customer Location-allocation (DC-LA) problem. DC-LA is based on the idea of changes in customer distribution over a defined period, and these changes have to be taken into account when establishing facilities to service changing customers distributions. This necessitated a dynamic stochastic evaluation function which came with a high computational cost due to a large number of simulations required in the evaluation process. In this paper, we investigate the use of racing, an approach used in model selection, to reduce the high computational cost by employing the minimum number of simulations for solution selection. Our adaptation of racing uses the Friedman test to compare solutions statistically. Racing allows simulations to be performed iteratively, ensuring that the minimum number of simulations is performed to detect a statistical difference. We present experiments using Population-Based Incremental Learning (PBIL) to explore the savings achievable from using racing in this way. Our results show that racing achieves improved cost savings over the dynamic stochastic evaluation function. We also observed that on average, the computational cost of racing was about 4.5 times lower than the computational cost of the full dynamic stochastic evaluation
Redefining noradrenergic neuromodulation of behavior : impacts of a modular locus coeruleus architecture
Peer reviewe
A search for ortho-benzyne (o-C6H4) in CRL 618
Polycyclic aromatic hydrocarbons (PAHs) have been proposed as potential
carriers of the unidentified infrared bands (UIRs) and the diffuse interstellar
bands (DIBs). PAHs are not likely to form by gas-phase or solid-state
interstellar chemistry, but rather might be produced in the outflows of
carbon-rich evolved stars. PAHs could form from acetylene addition to the
phenyl radical (C6H5), which is closely chemically related to benzene (C6H6)
and ortho-benzyne (o-C6H4). To date, circumstellar chemical models have been
limited to only a partial treatment of benzene-related chemistry, and so the
expected abundances of these species are unclear. A detection of benzene has
been reported in the envelope of the proto-planetary nebula (PPN) CRL 618, but
no other benzene-related species has been detected in this or any other source.
The spectrum of o-C6H4 is significantly simpler and stronger than that of C6H5,
and so we conducted deep Ku-, K- and Q-band searches for o-C6H4 with the Green
Bank Telescope. No transitions were detected, but an upper limit on the column
density of 8.4x10^13 cm^-2 has been determined. This limit can be used to
constrain chemical models of PPNe, and this study illustrates the need for
complete revision of these models to include the full set of benzene-related
chemistry.Comment: 13 pages, 4 figures, to be published in The Astrophysical Journal
Letter
Association of Basal Hyperglucagonemia with Impaired Glucagon Counterregulation in Type 1 Diabetes
Glucagon counterregulation (GCR) protects against hypoglycemia, but is impaired in type 1 diabetes (T1DM). A model-based analysis of in vivo animal data predicts that the GCR defects are linked to basal hyperglucagonemia. To test this hypothesis we studied the relationship between basal glucagon (BasG) and the GCR response to hypoglycemia in 29 hyperinsulinemic clamps in T1DM patients. Glucose levels were stabilized in euglycemia and then steadily lowered to 50 mg/dL. Glucagon was measured before induction of hypoglycemia and at 10 min intervals after glucose reached levels below 70 mg/dL. GCR was assessed by CumG, the cumulative glucagon levels above basal; MaxG, the maximum glucagon response; and RIG, the relative increase in glucagon over basal. Analysis of the results was performed with our mathematical model of GCR. The model describes interactions between islet peptides and glucose, reproduces the normal GCR axis and its impairment in diabetes. It was used to identify a control mechanism consistent with the observed link between BasG and GCR. Analysis of the clinical data showed that higher BasG was associated with lower GCR response. In particular, CumG and RIG correlated negatively with BasG (r = −0.46, p = 0.012 and r = −0.74, p < 0.0001 respectively) and MaxG increased linearly with BasG at a rate less than unity (p < 0.001). Consistent with these results was a model of GCR in which the secretion of glucagon has two components. The first is under (auto) feedback control and drives a pulsatile GCR and the second is feedback independent (basal secretion) and its increase suppresses the GCR. Our simulations showed that this model explains the observed relationships between BasG and GCR during a three-fold simulated increase in BasG. Our findings support the hypothesis that basal hyperglucagonemia contributes to the GCR impairment in T1DM and show that the predictive power of our GCR animal model applies to human pathophysiology in T1DM
Mechanistic Study of the Effect of Endothelin SNPs in Microvascular Angina – protocol of the PRIZE Endothelin Sub-Study
Introduction
Microvascular angina (MVA) is a common cause of ischemia with non-obstructive coronary arteries (INOCA) and limited therapeutic options are available to those affected. Endothelin-1 (ET-1) is a potent vasoconstrictor implicated in the pathophysiology of MVA. A large randomised, double blinded, placebo controlled crossover trial, the PRecIsion medicine with ZibotEntan in microvascular angina (PRIZE) trial is currently underway, investigating an endothelin receptor antagonist – Zibotentan, as a new drug treatment for microvascular angina. The trial uses a 'precision medicine' approach by preferential selection of those with higher ET-1 expression conferred by the PHACTR1 minor G allele single nucleotide polymorphism (SNP). The incidence of this SNP occurs in approximately one third of the population therefore a considerable number of screened patients will be ineligible for randomisation and the treatment phase of the trial.
Methods
In the PRIZE Endothelin (ET) Sub-Study, patients screened out of the PRIZE trial will be genotyped for other genetic variants in the ET-1 pathway. These will be correlated with phenotypic characteristics including exercise tolerance, angina severity and quantitative measures of microvascular function on cardiovascular MRI as well as mechanistic data on endothelin pathway signalling.
Conclusions
The study will provide a comprehensive genotype and phenotype bio-resource identifying novel ET-1 genotypes to inform the potential wider use of endothelin receptor antagonists for this indication.Wellcome Trust [WT107715/Z/15/Z, APD], British Heart Foundation [CB, RE/18/6134217], Medical Research Council [CB, MR/S018905/1], ].Jon Moulton Charity Trust [GRA, SPH
Observational Results of a Multi-Telescope Campaign in Search of Interstellar Urea [(NH)CO]
In this paper, we present the results of an observational search for gas
phase urea [(NH)CO] observed towards the Sgr B2(N-LMH) region. We show
data covering urea transitions from 100 GHz to 250 GHz from five
different observational facilities: BIMA, CARMA, the NRAO 12 m telescope, the
IRAM 30 m telescope, and SEST. The results show that the features ascribed to
urea can be reproduced across the entire observed bandwidth and all facilities
by best fit column density, temperature, and source size parameters which vary
by less than a factor of 2 between observations merely by adjusting for
telescope-specific parameters. Interferometric observations show that the
emission arising from these transitions is cospatial and compact, consistent
with the derived source sizes and emission from a single species. Despite this
evidence, the spectral complexity, both of (NH)CO and of Sgr B2(N),
makes the definitive identification of this molecule challenging. We present
observational spectra, laboratory data, and models, and discuss our results in
the context of a possible molecular detection of urea.Comment: 38 pages, 9 Figures, accepted in the Astrophysical Journa
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