Decomposability and scalability in space-based observatory scheduling

In this paper, we discuss issues of problem and model decomposition within the HSTS scheduling framework. HSTS was developed and originally applied in the context of the Hubble Space Telescope (HST) scheduling problem, motivated by the limitations of the current solution and, more generally, the insufficiency of classical planning and scheduling approaches in this problem context. We first summarize the salient architectural characteristics of HSTS and their relationship to previous scheduling and AI planning research. Then, we describe some key problem decomposition techniques supported by HSTS and underlying our integrated planning and scheduling approach, and we discuss the leverage they provide in solving space-based observatory scheduling problems

State-based scheduling: An architecture for telescope observation scheduling

The applicability of constraint-based scheduling, a methodology previously developed and validated in the domain of factory scheduling, is extended to problem domains that require attendance to a wider range of state-dependent constraints. The problem of constructing and maintaining a short-term observation schedule for the Hubble Space Telescope (HST), which typifies this type of domain is the focus of interest. The nature of the constraints encountered in the HST domain is examined, system requirements are discussed with respect to utilization of a constraint-based scheduling methodology in such domains, and a general framework for state-based scheduling is presented

Ab-initio theory of metal-insulator interfaces in a finite electric field

We present a novel technique for calculating the dielectric response of metal/insulator heterostructures. This scheme allows, for the first time, the fully first-principles calculation of the microscopic properties of thin-film capacitors at finite bias potential. The method can be readily applied to pure insulators, where it provides an interesting alternative to conventional finite-field techniques based on the Berry-phase formalism. We demonstrate the effectiveness of our method by performing comprehensive numerical tests on a model Ag/MgO/Ag heterostructure.Comment: 10 pages, 5 figures, major revisio

Constraint-based integration of planning and scheduling for space-based observatory management

Progress toward the development of effective, practical solutions to space-based observatory scheduling problems within the HSTS scheduling framework is reported. HSTS was developed and originally applied in the context of the Hubble Space Telescope (HST) short-term observation scheduling problem. The work was motivated by the limitations of the current solution and, more generally, by the insufficiency of classical planning and scheduling approaches in this problem context. HSTS has subsequently been used to develop improved heuristic solution techniques in related scheduling domains and is currently being applied to develop a scheduling tool for the upcoming Submillimeter Wave Astronomy Satellite (SWAS) mission. The salient architectural characteristics of HSTS and their relationship to previous scheduling and AI planning research are summarized. Then, some key problem decomposition techniques underlying the integrated planning and scheduling approach to the HST problem are described; research results indicate that these techniques provide leverage in solving space-based observatory scheduling problems. Finally, more recently developed constraint-posting scheduling procedures and the current SWAS application focus are summarized

Influence of the dual ABCB1 and ABCG2 inhibitor tariquidar on the disposition of oral imatinib in mice

<p>Abstract</p> <p>Background</p> <p>Imatinib, a tyrosine kinase inhibitor currently approved for treatment of several malignancies, has been shown to be a substrate for multiple efflux-transporter proteins, including ABCB1 (P-glycoprotein) and ABCG2 (BCRP). The effect of inhibiting these transporters on tissue exposure to imatinib remains unclear.</p> <p>Objective</p> <p>To assess the role of these transporters on drug disposition, 50 mg/kg imatinib was administered to Balb/C mice, 30 minutes after receiving tariquidar (10 mg/kg), an inhibitor of both ABCB1 and ABCG2, or vehicle, via oral gavage.</p> <p>Methods</p> <p>Quantitative determination of imatinib in mouse plasma, liver and brain was performed using a newly-developed and validated liquid-chromatography-mass spectrometric method. Results: Exposure to imatinib was 2.2-fold higher in plasma, liver and brain in mice that received tariquidar, as compared to those that received the vehicle (P = 0.001). The peak plasma concentration did not increase substantially, suggesting that tariquidar is affecting the distribution, metabolism and/or excretion of imatinib, rather than absorption. Though tariquidar increased the absolute exposure of imatinib, the brain-to-plasma ratio of imatinib was unaffected.</p> <p>Conclusion</p> <p>This study suggests that intentional inhibition of ABCB1 and ABCG2 function at the blood-brain barrier is unlikely to significantly improve clinical outcome of imatinib with currently used dosing regimens.</p

Serological evidence for non-lethal exposures of Mongolian wild birds to highly pathogenic avian influenza H5N1 virus.

Surveillance for highly pathogenic avian influenza viruses (HPAIV) in wild birds is logistically demanding due to the very low rates of virus detection. Serological approaches may be more cost effective as they require smaller sample sizes to identify exposed populations. We hypothesized that antigenic differences between classical Eurasian H5 subtype viruses (which have low pathogenicity in chickens) and H5N1 viruses of the Goose/Guangdong/96 H5 lineage (which are HPAIV) may be used to differentiate populations where HPAIVs have been circulating, from those where they have not. To test this we performed hemagglutination inhibition assays to compare the reactivity of serum samples from wild birds in Mongolia (where HPAIV has been circulating, n = 1,832) and Europe (where HPAIV has been rare or absent, n = 497) to a panel of reference viruses including classical Eurasian H5 (of low pathogenicity), and five HPAIV H5N1 antigens of the Asian lineage A/Goose/Guangdong/1/96. Antibody titres were detected against at least one of the test antigens for 182 Mongolian serum samples (total seroprevalence of 0.10, n = 1,832, 95% adjusted Wald confidence limits of 0.09-0.11) and 25 of the European sera tested (total seroprevalence of 0.05, n = 497, 95% adjusted Wald confidence limits of 0.03-0.07). A bias in antibody titres to HPAIV antigens was found in the Mongolian sample set (22/182) that was absent in the European sera (0/25). Although the interpretation of serological data from wild birds is complicated by the possibility of exposure to multiple strains, and variability in the timing of exposure, these findings suggest that a proportion of the Mongolian population had survived exposure to HPAIV, and that serological assays may enhance the targeting of traditional HPAIV surveillance toward populations where isolation of HPAIV is more likely.Funding for this work was provided by the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), and the Department of Health and Human Services under contracts HHSN266200700007C and HHSN266200700010C. Further support was provided through a doctoral training grant to MG by the Biotechnology and Biological Sciences Research Council (BB/F016786/1).This is the final version of the article. It first appeared from PLOS via http://dx.doi.org/ 10.1371/journal.pone.011356

On the non-Gaussianity from Recombination

The non-linear effects operating at the recombination epoch generate a non-Gaussian signal in the CMB anisotropies. Such a contribution is relevant because it represents a major part of the second-order radiation transfer function which must be determined in order to have a complete control of both the primordial and non-primordial part of non-Gaussianity in the CMB anisotropies. We provide an estimate of the level of non-Gaussianity in the CMB arising from the recombination epoch which shows up mainly in the equilateral configuration. We find that it causes a contamination to the possible measurement of the equilateral primordial bispectrum shifting the minimum detectable value of the non-Gaussian parameter f^equil_NL by Delta f^equil_NL= O(10) for an experiment like Planck.Comment: LaTeX file; 11 pages. v2: Typos corrected; references added; comments about the effective non-linearity parameter added in Sec. IV; comments added in the conclusions of Sec. IV. v3: References added; some clarifications added as footnotes 4 and 6, and in Sec. 3. Matches version accepted for publication in JCA

Comparison of a web-based package with tutor-based methods of teaching respiratory medicine: subjective and objective evaluations

BackgroundRespiratory disease is a major cause of morbidity and mortality not only in the United Kingdom, but globally. A good understanding of respiratory disease and its treatment is essential for all medical graduates. As a result of changes in clinical practice, patients with some common respiratory illnesses are less often admitted to hospital, restricting the experience available to undergraduate students. Combined with a potential shortage of clinical teachers, this means that new methods of teaching need to be developed and appraised. The aim of this study was to establish whether a web-based package on the diagnosis of respiratory disease would be as effective and as acceptable to final year medical students as tutor-led methods of teaching the same material.Methods137 out of 315 final year undergraduate students in a single medical school volunteered to take part. Each received up to two hours of tutor-lead interactive, tutor-lead didactic or electronic, Web-based teaching on the accurate diagnosis and management of respiratory disease. Post teaching performance was assessed by multiple true/false questions and data interpretation exercises, whilst students' teaching preferences were assessed by questionnaire.ResultsDespite a high knowledge baseline before the study, there was a small, but statistically significant increase in knowledge score after all forms of teaching. Similarly, data interpretation skills improved in all groups, irrespective of teaching format, Although paradoxically most students expressed a preference for interactive tutor-lead teaching, spirometry interpretation in those receiving web-based teaching improved significantly more [p = 0.041] than in those in the interactive group.ConclusionWeb-based teaching is at least as good as other teaching formats, but we need to overcome students' reluctance to engage with this teaching method

Exploring views on satisfaction with life in young children with chronic illness: an innovative approach to the collection of self-report data from children under 11

The objective of this study was to explore young children’s views on the impact of chronic illness on their life in order to inform future development of a patient-based self-report health outcome measure. We describe an approach to facilitating self-report views from young children with chronic illness. A board game was designed in order to obtain qualitative data from 39 children with a range of chronic illness conditions and 38 healthy controls ranging in age from 3 to 11 years. The format was effective in engaging young children in a self-report process of determining satisfaction with life and identified nine domains. The board game enabled children aged 5–11 years with chronic illness to describe the effects of living with illness on home, family, friends, school and life in general. It generated direct, non-interpreted material from children who, because of their age, may have been considered unable or limited their ability to discuss and describe how they feel. Obtaining this information for children aged 4 and under continues to be a challenge

Why is spirometry underused in the diagnosis of the breathless patient: a qualitative study

BackgroundUse of spirometry is essential for the accurate diagnosis of respiratory disease but it is underused in both primary and specialist care. In the current study, we have explored the reasons for this underuse.MethodsFive separate focus groups were undertaken with final year medical undergraduates, junior hospital doctors, general practitioners (GPs) and specialist trainees in respiratory medicine. The participants were not told prior to the session that we were specifically interested in their views about spirometry but discussion was moderated to elicit their approaches to the diagnosis of a breathless patient, their use of investigations and their learning preferences.ResultsUndergraduates and junior doctors rarely had a systematic approach towards the breathless patient and tended, unless prompted, to focus on the emergency room situation rather than on patients with longer term causes of breathlessness. Whilst their theoretical knowledge embraced the possibility of a non-respiratory cause for breathlessness, neither undergraduates nor junior doctors spontaneously mentioned the use of spirometry in the diagnosis of respiratory disease. When prompted they cited lack of familiarity with the use and location of equipment, and lack of encouragement to use it as being major barriers to utilization. In contrast, GPs and specialist respiratory trainees were enthusiastic about its use and perceived spirometry as a core element of the diagnostic workup.ConclusionsMore explicit training is needed regarding the role of spirometry in the diagnosis and management of those with lung disease and this necessitates both practical experience and training in interpretation of the data. However, formal teaching is likely to be undermined in practice, if the concept is not strongly promoted by the senior staff who act as role models and trainers