4,609 research outputs found
The Brauer-Manin Obstruction and Sha[2].
We discuss the Brauer-Manin obstruction on del Pezzo surfaces of degree 4. We outline a detailed algorithm for computing the obstruction and provide associated programs in magma. This is illustrated with the computation of an example with an irreducible cubic factor in the singular locus of the defining pencil of quadrics (in contrast to previous examples, which had at worst quadratic irreducible factors). We exploit the relationship with the Tate-Shafarevich group to give new types of examples of Sha[2], for families of curves of genus 2 of the form y^2 = f(x), where f(x) is a quintic containing an irreducible cubic factor
Prosthesis coupling
A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump
An urban planning program at Roxbury Community College : a feasibility study
Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1980.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: leaves 133-136.by Hazel V. Bright.M.C.P
Milestones: a mixed methods study of an educational intervention to improve care of the dying
Background: Approximately 460 000 people die annually in England. Three-quarters of these deaths are expected. Health Education England is prioritising upskilling of clinical staff in response to reports of poor care quality in the last days of life in acute hospitals, where almost half of all deaths occur. This study explores the impact of an end-of-life care (EoLC) educational intervention, Milestones, in acute hospital trusts in Greater London.
Methods: This is a mixed methods study. Learners completed a questionnaire pre- (n=452), immediately post- (n=488) and 3 to 8 months post- (n=37) intervention. The questionnaire measured learner confidence in EoLC covering the National Health Service adopted ‘Priorities for the Care of the Dying Person’. Paired t-tests were used to determine statistically significant difference in learner confidence pre- and post-intervention. A convenience sample of learners (n=7) and educators (n=5) were recruited to qualitative semi-structured interviews that sought to understand if, how and why Milestones worked. Data were analysed using a thematic approach.
Results: A statistically significant increase in learner confidence across all five priorities of care’ was sustained up to 8 months (p<0.001). Interviewees wanted to discuss wider challenges in EoLC related to the organisations and cultural contexts in which they worked. Concerns included balancing hope when decision-making, learning as a multidisciplinary team and emotional impact.
Conclusion: The findings suggest that Milestones is a flexible, beneficial resource for teaching EoLC that facilitates enhanced learner engagement. Understanding generated about wider concerns can inform future educational material development, organisational process and research study design
Wind Power Frequency Control in Doubly FED Induction Generator Using CFMPC-FOPID Controller Scheme
Because the majority of wind turbines operate in maximum output power tracking mode, power system frequency cannot be supported. However, if the penetration rate of wind power increases, the system inertia related to frequency modulation may decrease. In addition, frequency stability will be severely affected in the event of significant disturbances to the system load. Due to the high penetration of wind power in isolated power systems, this study suggests a coordinated frequency management approach for emergency frequency regulation. In order to prevent the phenomenon of load frequency control in doubly fed induction generators (DFIGs), a unique efficient control scheme is developed. The Cascaded Fractional Model Predictive Controller coupled with Fractional-Order PID controller (CFMPC-FOPID) is developed to provide the DFIG system with an efficient reaction to changes in load and system parameters. The proposed controller must have a robust tendency to respond quickly in terms of minimum settling time, undershoot, and overshoot. Nonlinear feedback controllers are designed using frequency deviations and power imbalances to achieve the reserve power distribution between generators and DFIGs in a variety of wind speed conditions. It makes upgrading quick and easy. In Matlab/Simulink, a simulation model is built to test the viability of the suggested approach
Probiotic effects of lactic acid bacteria against Vibrio alginolyticus in Penaeus (Fenneropenaeus) indicus (H. Milne Edwards)
Cell free extracts of four strains of Lactic acid bacteria (LAB) viz. Lactobacillus. acidophilus,
Streptococcus.cremoris, Lactobacillus bulgaricus –56 and Lactobacillus bulgaricus –57 inhibited
growth of Vibrio alginolyticus in nutrient broth. The antagonism of LAB to Vibrio
alginolyticus was further confirmed by streak plating wherein suppression of growth of Vibrio
was obtained.
Juveniles of Penaeus indicus (average weight 0.985 ± 0.1 g) on administering orally a
moist feed base containing 5 × 106 cells·g of the four LAB probionts for a period of four weeks
showed better survival (56 to 72%) when challenged with V. alginolyticus by intra-muscular
injection of 0.1 ml containing 3 × 109 cells·ml. Animals maintained on a diet devoid of bacterial
biomass exhibited 80% mortality
Effective Hamiltonian Approach to Hyperon Beta Decay with Final-State Baryon Polarization
Using an effective Hamiltonian approach, we obtain expressions for hyperon
beta decay final-state baryon polarization. Terms through second order in the
energy release are retained. The resulting approximate expressions are much
simpler and more compact than the exact expressions, and they agree closely
with them.Comment: 1 Figure Will appear in Phys Rev D 60 Article 117505 (Dec 1, 1999
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Dynamic neural network architectures for on field stochastic calibration of indicative low cost air quality sensing systems
In the last few years, the interest in the development of new pervasive or mobile implementations of air quality multisensor devices has significantly grown. New application opportunities appeared together with new challenges due to limitations in dealing with rapid pollutants concentrations transients both for static and mobile deployments. In this work, we propose a Dynamic Neural Network (DNN) approach to the stochastic prediction of air pollutants concentrations by means of chemical multisensor devices. DNN architectures have been devised and tested in order to tackle the cross sensitivities issues and sensors inherent dynamic limitations. Testing have been performed using an on-field recorded dataset from a pervasive deployment in Cambridge (UK), encompassing several weeks. The results obtained with the dynamic model are compared with the response of the static neural network and the performance analysis indicates the capability of the on-field dynamic multivariate calibration to ameliorate the static calibration approach performance in this real world air quality monitoring scenario. Interestingly, results analysis also suggests that the improvements are more significant when pollutants concentration changes more rapidly.This work has been supported by an STSM (Short Term Scientific Mission) grant from COST Action TD1105 EuNetAir
Early Growth and Development Impairments in Patients with Ganglioside GM3 Synthase Deficiency
Ganglioside GM3 synthase is a key enzyme involved in the biosynthesis of gangliosides. GM3 synthase deficiency (GSD) causes a complete absence of GM3 and all downstream biosynthetic derivatives. The individuals affected by this disorder manifest severe irritability, intractable seizures and profound intellectual disability. However, we have found that most newborns seem symptom-free for a period of time after birth. In order to further understand the onset of the disease, we investigated the early growth and development of patients with this condition through this study. We compared 37 affected individuals with their normal siblings and revealed that all children with GSD had relatively normal intrauterine growth and development, as their weight, length and head circumference were similar to their normal siblings at birth. However, the disease progresses quickly after birth and causes significant constitutional impairments of growth and development by 6 months of age. Neither breastfeeding nor gastrostomy tube placement made significant difference on growth and development as all groups of patients showed the similar pattern. We conclude that GSD causes significant postnatal growth and developmental impairments and the amount of gangliosides in breast milk and general nutritional intervention do not seem to alter these outcomes
Stepwise Hydrogen Atom and Proton Transfers in Dioxygen Reduction by Aryl-Alcohol Oxidase
The mechanism of dioxygen reduction by the flavoenzyme aryl-alcohol oxidase was investigated with kinetic isotope, viscosity, and pL (pH/pD) effects in rapid kinetics experiments by stopped-flow spectrophotometry of the oxidative half-reaction of the enzyme. Double mixing of the enzyme in a stopped-flow spectrophotometer with [a-2H2]-p-methoxybenzyl alcohol and oxygen at varying aging times established a slow rate constant of 0.0023 s-1 for the wash-out of the D atom from the N5 atom of the reduced flavin. Thus, the deuterated substrate could be used to probe the cleavage of the N-H bond of the reduced flavin in the oxidative half-reaction. A significant and pH-independent substrate kinetic isotope effect (KIE) of 1.5 between pH 5.0 and 8.0 demonstrated that H transfer is partially limiting the oxidative half-reaction of the enzyme; a negligible solvent KIE of 1.0 between pD 5.0 and 8.0 proved a fast H+ transfer reaction that does not contribute to determining the flavin oxidation rates. Thus, a mechanism for dioxygen reduction in which the H atom originating from the reduced flavin and a H+ from a solvent exchangeable site are transferred in separate kinetic steps is proposed. The spectroscopic and kinetic data presented also showed a lack of stabilization of transient flavin intermediates. The substantial differences in the mechanistic details of O2 reduction by aryl-alcohol oxidase with respect to other alcohol oxidases like choline oxidase, pyranose 2-oxidase, and glucose oxidase further demonstrate the high level of versatility of the flavin cofactor in flavoenzymes
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