1,001 research outputs found

    A geometric constraint over k-dimensional objects and shapes subject to business rules

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    This report presents a global constraint that enforces rules written in a language based on arithmetic and first-order logic to hold among a set of objects. In a first step, the rules are rewritten to Quantifier-Free Presburger Arithmetic (QFPA) formulas. Secondly, such formulas are compiled to generators of k-dimensional forbidden sets. Such generators are a generalization of the indexicals of cc(FD). Finally, the forbidden sets generated by such indexicals are aggregated by a sweep-based algorithm and used for filtering. The business rules allow to express a great variety of packing and placement constraints, while admitting efficient and effective filtering of the domain variables of the k-dimensional object, without the need to use spatial data structures. The constraint was used to directly encode the packing knowledge of a major car manufacturer and tested on a set of real packing problems under these rules, as well as on a packing-unpacking problem

    Development and validation of a patient‐assessed gastroparesis symptom severity measure: the Gastroparesis Cardinal Symptom Index

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    SummaryBackground : Patient‐based symptom assessments are necessary to evaluate the effectiveness of medical treatments for gastroparesis.Aim : To summarize the development and measurement qualities of the Gastroparesis Cardinal Symptom Index (GCSI), a new measure of gastroparesis‐related symptoms.Methods : The GCSI was based on reviews of the medical literature, clinician interviews and patient focus groups. The measurement qualities (i.e. reliability, validity) of the GCSI were examined in 169 gastroparesis patients. Patients were recruited from seven clinical centres in the USA to participate in this observational study. Patients completed the GCSI, SF‐36 Health Survey and disability day questions at a baseline visit and again after 8 weeks. Clinicians independently rated the severity of the patients' symptoms, and both clinicians and patients rated the change in gastroparesis‐related symptoms over the 8‐week study.Results: The GCSI consists of three sub‐scales: post‐prandial fullness/early satiety, nausea/vomiting and bloating. The internal consistency reliability was 0.84 and the test–re‐test reliability was 0.76 for the GCSI total score. Significant relationships were observed between the clinician‐assessed symptom severity and the GCSI total score, and significant associations were found between the GCSI scores and SF‐36 physical and mental component summary scores and restricted activity and bed disability days. Patients with greater symptom severity, as rated by clinicians, reported greater symptom severity on the GCSI. The GCSI total scores were responsive to changes in overall gastroparesis symptoms as assessed by clinicians (P = 0.0002) and patients (P = 0.002).Conclusion: The findings of this study indicate that the GCSI is a reliable and valid instrument for measuring the symptom severity in patients with gastroparesis

    Community phenology of insects on oak:Local differentiation along a climatic gradient

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    Climate change is advancing the onset of phenological events, with the rate of advance varying among species and trophic levels. In addition, local populations of the same species may show genetic differences in their response to seasonal cues. If populations of interacting species differ in their response, then climate change may result in geographically varying shifts in the community-level distribution of interaction strength. We explored the magnitude of trophic- and species-level responses to temperature in a tritrophic system comprising pedunculate oak, insect herbivores, and their associated parasitoids. We sampled local realizations of this community at five sites along a transect spanning fifteen degrees of latitude. Samples from each trophic level at each site were exposed to the same set of five climatic regimes during overwintering in climate chambers. We then recorded the number of days and degree-days required for oak acorns to develop and insects to emerge. In terms of dates of events, phenology differed among populations. In terms of degree-days, we found that for two species pairs, the heat sum required to develop in spring differed by an additional similar to 500 degree-days between trophic levels when overwintering at the highest temperature. For three species, within-population variation in the number of degree-days required for emergence was higher at warmer temperatures. Our findings suggest that changing temperatures can modify interactions within a community by altering the relative phenology of interacting species and that some interactions are more vulnerable than others to a shift in temperature. The geographic variation in the phenological response of a species suggests that there is a genetic component in determining the phenology of local populations. Such local variation blended with interspecific differences in responses makes it complex to understand how communities will respond to warmer temperatures

    Defecatory urge increases cognitive control and intertemporal patience in healthy volunteers

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    Background: Past research has demonstrated that moderate urge to urinate improves inhibitory control, specifically among participants with higher behavioral inhibition sensitivity (BIS). The effect was absent when the urge exceeded intolerable level. The present research examines whether rectal distension-induced urge to defecate has similar effects. Methods: The moderate and high defecatory urge were induced by rectal distension in healthy volunteers (n=35), while they completed Stroop task and monetary delay discounting task. The difference of average reaction time between incongruent and congruent trials in the Stroop task (Stroop interference) and the preference for larger-later rewards in the delay discounting task were the primary outcomes. Key Results: Participants with high BIS (n=17) showed greater ability to inhibit their automatic response tendencies, as indexed by their Stroop interference, under moderate urge relative to no urge (128±41 ms vs. 202±37 ms, t64=2.07; p=0.021, Cohen’s d: 0.44), but not relative to high urge (154±45 ms, t64=1.20; p=0.12, Cohen’s d: 0.30). High BIS participants also showed a higher preference for larger-later reward in the delay discounting task under high (odds ratio = 1.51 [1.02–2.25], p=0.039) relative to no urge, but not relative to moderate urge (odds ratio = 1.02 [0.73–1.42], p = 0.91). In contrast, rectal distension did not influence performance on either of the tasks in participants with low BIS (n=18). Conclusions and inference: These findings may be interpreted as a ‘spill-over’ effect of inhibition of the urge to defecate to volitional cognitive control among healthy participants with high BIS

    Lack of Relationship Between Chronic Upper Abdominal Symptoms and Gastric Function in Functional Dyspepsia

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    To determine the relationship between gastric function and upper abdominal sensations we studied sixty FD patients (43 female). All patients underwent three gastric function tests: 13C octanoic gastric emptying test, three-dimensional ultrasonography (proximal and distal gastric volume), and the nutrient drink test. Upper abdominal sensations experienced in daily life were scored using questionnaires. Impaired proximal gastric relaxation (23%) and a delayed gastric emptying (33%) are highly prevalent in FD patients; however, only a small overlap exists between the two pathophysiologic disorders (5%). No relationship was found between chronic upper abdominal symptoms and gastric function (proximal gastric relaxation, gastric emptying rate, or drinking capacity) (all P > 0.01). Proximal gastric relaxation or gastric emptying rate had no effect on maximum drinking capacity (P > 0.01). The lack of relationship between chronic upper abdominal sensations and gastric function questions the role of these pathophysiologic mechanisms in the generation of symptoms

    HYTHIRM Radiance Modeling and Image Analyses in Support of STS-119, STS-125 and STS-128 Space Shuttle Hypersonic Re-entries

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    We provide the first geometrically accurate (i.e., 3-D) temperature maps of the entire windward surface of the Space Shuttle during hypersonic reentry. To accomplish this task we began with estimated surface temperatures derived from CFD models at integral high Mach numbers and used them, the Shuttle's surface properties and reasonable estimates of the sensor-to-target geometry to predict the emitted spectral radiance from the surface (in units of W sr-1 m-2 nm-1). These data were converted to sensor counts using properties of the sensor (e.g. aperture, spectral band, and various efficiencies), the expected background, and the atmosphere transmission to inform the optimal settings for the near-infrared and midwave IR cameras on the Cast Glance aircraft. Once these data were collected, calibrated, edited, registered and co-added we formed both 2-D maps of the scene in the above units and 3-D maps of the bottom surface in temperature that could be compared with not only the initial inputs but also thermocouple data from the Shuttle itself. The 3-D temperature mapping process was based on the initial radiance modeling process. Here temperatures were guessed for each node in a well-resolved 3-D framework, a radiance model was produced and compared to the processed imagery, and corrections to the temperature were estimated until the iterative process converged. This process did very well in characterizing the temperature structure of the large asymmetric boundary layer transition the covered much of the starboard bottom surface of STS-119 Discovery. Both internally estimated accuracies and differences with CFD models and thermocouple measurements are at most a few percent. The technique did less well characterizing the temperature structure of the turbulent wedge behind the trip due to limitations in understanding the true sensor resolution. (Note: Those less inclined to read the entire paper are encouraged to read an Executive Summary provided at the end.

    Delayed gastric emptying and reduced postprandial small bowel water content of equicaloric whole meal bread versus rice meals in healthy subjects: novel MRI insights

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    BACKGROUND/OBJECTIVES: Postprandial bloating is a common symptom in patients with functional gastrointestinal (GI) diseases. Whole meal bread (WMB) often aggravates such symptoms though the mechanisms are unclear. We used magnetic resonance imaging (MRI) to monitor the intragastric fate of a WMB meal (11% bran) compared to a rice pudding (RP) meal. SUBJECTS/METHODS: 12 healthy volunteers completed this randomised crossover study. They fasted overnight and after an initial MRI scan consumed a glass of orange juice with a 2267 kJ WMB or an equicaloric RP meal. Subjects underwent serial MRI scans every 45 min up to 270 min to assess gastric volumes and small bowel water content and completed a GI symptom questionnaire. RESULTS: The MRI intragastric appearance of the two meals was markedly different. The WMB meal formed a homogeneous dark bolus with brighter liquid signal surrounding it. The RP meal separated into an upper, liquid layer and a lower particulate layer allowing more rapid emptying of the liquid compared to solid phase (sieving). The WMB meal had longer gastric half emptying times (132±8 min) compared to the RP meal (104±7 min), P<0.008. The WMB meal was associated with markedly reduced MRI-visible small bowel free mobile water content compared to the RP meal, P<0.0001. CONCLUSIONS: WMB bread forms a homogeneous bolus in the stomach which inhibits gastric sieving and hence empties slower than the equicaloric rice meal. These properties may explain why wheat causes postprandial bloating and could be exploited to design foods which prolong satiation

    Application of a Near Infrared Imaging System for Thermographic Imaging of the Space Shuttle during Hypersonic Re-Entry

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    High resolution calibrated near infrared (NIR) imagery was obtained of the Space Shuttle s reentry during STS-119, STS-125, and STS-128 missions. The infrared imagery was collected using a US Navy NP-3D Orion aircraft using a long-range infrared optical package referred to as Cast Glance. The slant ranges between the Space Shuttle and Cast Glance were approximately 26-41 nautical miles at point of closest approach. The Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) project was a NASA Langley led endeavor sponsored by the NASA Engineering Safety Center, the Space Shuttle Program Office and the NASA Aeronautics Research Mission Directorate to demonstrate a quantitative thermal imaging capability. HYTHIRM required several mission tools to acquire the imagery. These tools include pre-mission acquisition simulations of the Shuttle trajectory in relationship to the Cast Glance aircraft flight path, radiance modeling to predict the infrared response of the Shuttle, and post mission analysis tools to process the infrared imagery to quantitative temperature maps. The spatially resolved global thermal measurements made during the Shuttle s hypersonic reentry provides valuable flight data for reducing the uncertainty associated with present day ground-to-flight extrapolation techniques and current state-of-the-art empirical boundary-layer transition or turbulent heating prediction methods. Laminar and turbulent flight data is considered critical for the development of turbulence models supporting NASA s next-generation spacecraft. This paper will provide the motivation and details behind the use of an upgraded NIR imaging system used onboard a Navy Cast Glance aircraft and describe the characterizations and procedures performed to obtain quantitative temperature maps. A brief description and assessment will be provided of the previously used analog NIR camera along with image examples from Shuttle missions STS-121, STS-115, and solar tower test. These thermal observations confirmed the challenge of a long-range acquisition during re-entry. These challenges are due to unknown atmospheric conditions, image saturation, vibration etc. This provides the motivation for the use of a digital NIR sensor. The characterizations performed on the digital NIR sensor included radiometric, spatial, and spectral measurements using blackbody radiation sources and known targets. An assessment of the collected data for three Space Shuttle atmospheric re-entries, STS-119, STS-125, and STS-128, are provided along with a description of various events of interest captured using the digital NIR imaging system such as RCS firings and boundary layer transitions. Lastly the process used to convert the raw image counts to quantitative temperatures is presented along with comparisons to the Space Shuttle's onboard thermocouples
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