8,254 research outputs found
Experimental demonstration of holographic three-dimensional light shaping using a Gerchberg-Saxton algorithm
We use a three-dimensional Gerchberg–Saxton algorithm (Shabtay (2003) Opt. Commun. 226 33) to calculate the Fourier-space representation of physically realizable light beams with arbitrarily shaped three-dimensional intensity distributions. From this representation we extract a phase-hologram pattern that allows us to create such light beams experimentally. We show several examples of experimentally shaped light beams
The large scale geometry of some metabelian groups
We study the large scale geometry of the upper triangular subgroup of
PSL(2,Z[1/n]), which arises naturally in a geometric context. We prove a
quasi-isometry classification theorem and show that these groups are
quasi-isometrically rigid with infinite dimensional quasi-isometry group. We
generalize our results to a larger class of groups which are metabelian and are
higher dimensional analogues of the solvable Baumslag-Solitar groups BS(1,n)
Vortex sorter for Bose-Einstein condensates
We have designed interferometers that sort Bose-Einstein condensates into
their vortex components. The Bose-Einstein condensates in the two arms of the
interferometer are rotated with respect to each other through fixed angles;
different vortex components then exit the interferometer in different
directions. The method we use to rotate the Bose-Einstein condensates involves
asymmetric phase imprinting and is itself new. We have modelled rotation
through fixed angles and sorting into vortex components with even and odd
values of the topological charge of 2-dimensional Bose-Einstein condensates in
a number of states (pure or superposition vortex states for different values of
the scattering length). Our scheme may have applications for quantum
information processing.Comment: 4 pages, high resolution figures can be obtained from the author
The first experimental flight package of an advanced telemetry system with adaptive capability Technical summary report, 1 Jul. 1963 - 15 Feb. 1965
Mechanical design, and environmental and functional testing of advanced telemetry system flight package with adaptive capabilit
The validity of capillary blood sampling in the determination of human growth hormone concentration during exercise in men
This is an open access article - Copyright © 2004 BMJ Publishing Group LtdBACKGROUND: Studies measuring human growth hormone (hGH) in blood during exercise have mainly used venous sampling. The invasive nature of this procedure makes evaluation of hGH impossible in various exercise environments.
OBJECTIVE: To determine whether capillary sampling could offer an alternative sampling method.
METHODS: Capillary and venous blood samples were collected for determination of hGH at the end of each exercise stage during an incremental exercise test in 16 male club level competitive cyclists (mean (SD) age 30.8 (8.0) years, body mass 72.2 (7.1) kg, body fat 12.9 (3.5)%, peak oxygen consumption 4.18 (0.46) l⋅min−1). Linear regression, from a plot of venous v capillary blood hGH concentration, showed a correlation coefficient of r = 0.986 (p<0.001). When geometric means and log transformations were used, a coefficient of variation of 14.2% was demonstrated between venous and capillary flow for hGH concentration. The mean ratio limits of agreement were 0.62 (1.72)—that is, 95% of the ratios were contained between 0.36 and 1.07, with a mean of 0.62.
CONCLUSIONS: Capillary blood sampling is an acceptable alternative to venous sampling for determining hGH concentration during rest and exercise. Sample sites should not be used interchangeably: one site should be chosen and its use standardised
Structural and Aerodynamic Design, Procedure and Analysis of a Small V-shaped Vertical Axis Wind Turbine
Over the last two decades there has been a renewed interest in Vertical Axis Wind Turbines. This turbine configuration though unpopular for large-scale generation has found a niche market in the way of offshore energy harvesting. However, offshore wind has its challenges. In this thesis a detailed comprehensive study of a proposed V-shaped vertical axis turbine rotor is performed in order to examine its structural and aerodynamic characteristics. The design met and exceeded the safety parameters establish for test bed operation, showing a factor of safety of 1.87 with regard to fatigue stress response. A satisfactory fatigue stress design life was also achieved. Both experimental and numerical aerodynamic data have relatively good agreement achieving an overall maximum power coefficient of 0.2589 numerically and 0.251 experimentally
The evolution of Condorcet’s ideas during the revolution
Introduction Aim of the thesis: (a) to show to what extent Condorcet's ideas were influenced by those of the eighteenth century "philosophes"; (b) to show how the inconsistencies in his behaviour were not as important as has been said; and were due to the need to adapt the reform project he had drawn up before 1789 to the events of 1789-93; (c) to show to what extent the Girondin constitutional project grew out of Condorcet's original reform plan; (d) to illustrate the difficulties experienced generally by political theorists when seeking to put their ideas into practice. Chapter I An examination of Condorcet's reform plans between 1775 and 1789. 1. The doctrine of the Rights of Man: its ideological basis. 2. The reform plans: (a) Constitutional reform: how Condorcet wished to establish a "democratic" constitution which would reconcile the ideal of "popular sovereignty" with the necessity for a representative system of government. (b) The reforms of the major abuses in the judicature, the penal system and the tax system. Chapter II An examination of Condorcet's ideas between August 1788 and June 1791. 1. The summoning and opening of Etats-Generaux. Condorcet's disappointment and his attempts to ensure that they were transformed into a National Assembly. 2. The Constituent Assembly: (a) Condorcet's work as a member of the Commufie's general assembly in the field of local government and electoral reform. (b) His attempt to establish a centre party between May 1790 and May 1791. (c) His reactions to the Constituent Assembly's reforms of the judicature, the penal system, the tax system and the organisation of the Church. Chapter III An examination of the evolution of Condorcet's ideas between the King's flight and the 10th August revolution. 1. From the King's flight to the meeting of the Legislative Assembly. The evolution of Condorcet's ideas in the field of executive reform. 2. The Legislative Assembly:(a) The "loyalty" policy, October 1791. (b) The slide into war, November 1791 to April 1792. (c) The 10th August revolution and Condorcet's reaction to it. Chapter IV An examination of Condorcet's activities and writings between 10th August 1792 and his death. 1. From 10th August to the meeting of the Convention. 2. The Convention: (a) His relations with the Girondins and the Montagnards. (b) His attitude towards the King's trial. (c) His election to the constitutional committee. 3. An examination of the Girondin constitutional project. 4. The rejection of the project and Condorcet's end. Conclusion Condorcet's behaviour during the Revolution was dictated by one important need - that of adapting a long-term project for political reform to the period of swift change which took place in the years following 1789
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Investigating Associations between Consumption of Unprocessed and Ultra Processed Foods and Maternal and Neonatal Health Outcomes—Secondary Outcomes of LIFT Trial
The ultra-processing of food has become a much more important aspect of dietary patterns and dietary quality in terms of its impact on body weight, diet related diseases, health, and well-being in the past decades. NOVA is a set of guidelines developed that classifies diet quality by degree of food processing. The NOVA guidelines distinguish four categories: unprocessed /minimally processed foods; culinary ingredients; processed foods; and ultra-processed foods. Numerous studies have found an association of ultra-processed foods and health conditions such as obesity and metabolic syndrome. This study analyzed the associations between maternal diet quality as measured by NOVA and maternal anthropometric and neonatal body composition outcomes. The optimal method of nutrition intervention and education for this special population remains unknown; using NOVA may provide researchers with a different lens to assess diet quality and health care professionals with additional vocabulary to convey more tailored messages regarding optimal nutrition strategies for mother and offspring. Using data collected from a large randomized controlled intervention trial at pre and post intervention, this study aimed to compare the NOVA guidelines assessment of maternal diet quality to the parent study assessment of diet quality, the Healthy Eating Index (HEI), using statistical correlations. Secondly, this study aimed to look at the relationship of ultra-processed food intake to the maternal gestational weight gain experience using a logistic regression. Thirdly, this dissertation aimed to explore the relationship between maternal ultra-processed food intake and neonatal lean mass as measured by quantitative magnetic resonance (QMR) and fat free mass as measured by air displacement plethysmography (ADP: PEAPOD).
In terms of maternal outcomes, the study found that NOVA and HEI were significantly correlated at pre intervention but not at post intervention. The odds of gaining excessive gestational weight decreased as maternal ultra-processed food intake increased - which was not in the hypothesized direction - when using study participant data. However, the odds of gaining excessive gestational weight increased as maternal ultra-processed food intake increased - which was in the hypothesized direction - when using the Institute of Medicine weight gain recommendations. Also, while obesity did not predict excessive gestational weight gain, those with obesity ultra-processed food intake did predict gestational weight gain. These various inconsistencies are likely due to the instability of the dietary intake data because only one 24 -hour dietary recall was obtained from mother. In addition, the mothers’ diets were very healthy to begin with, where ultra-processed food intake formed about 45% of calories both pre and post intervention, when the national average is 57%. Race was also significant predictors of gestational weight gain for the mothers. Being non-white significantly increased the odds of gaining excessively as did the interaction of having obesity and eating more ultra-processed foods.
In terms of neonatal outcomes, findings from this study suggest that length and fat mass are significant predictors of lean mass in neonates. In terms of the impact of maternal ultra-processed food intake, the higher the consumption of ultra-processed food, the greater the neonatal lean mass, which this was not in the hypothesized direction. However, the association was minimal with very small beta weights and regression line, when plotted was quite flat, so that the finding is not clinically meaningful.
It remains important to know whether maternal ultra-processed food intake influences gestational weight gain and the body composition of the neonate. Thus, future research should include using similar data analyses on a population with a more nationally representative diet, a larger sample size, and a more robust measure of dietary intake such as three 24-hour recalls. Given that a similar recent study found ultra-processed food to be highly predictive of maternal and neonatal outcomes, and many other studies have demonstrated that ultra-processed food is related to several health conditions in many countries that this study did not measure, it seems prudent for healthcare providers to take advantage of prenatal visits as a window of opportunity to encourage the consumption of unprocessed and minimally foods and help women make informed decisions regarding ultra-processed foods
Multiple range imaging camera operation with minimal performance impact
Time-of-flight range imaging cameras operate by illuminating a scene with amplitude modulated light and measuring the phase shift of the modulation envelope between the emitted and reflected light. Object distance can then be calculated from this phase measurement. This approach does not work in multiple camera environments as the measured phase is corrupted by the illumination from other cameras. To minimize inaccuracies in multiple camera environments, replacing the traditional cyclic modulation with pseudo-noise amplitude modulation has been previously demonstrated. However, this technique effectively reduced the modulation frequency, therefore decreasing the distance measurement precision (which has a proportional relationship with the modulation frequency). A new modulation scheme using maximum length pseudo-random sequences binary phase encoded onto the existing cyclic amplitude modulation, is presented. The effective modulation frequency therefore remains unchanged, providing range measurements with high precision. The effectiveness of the new modulation scheme was verified using a custom time-of-flight camera based on the PMD19-K2 range imaging sensor. The new pseudo-noise modulation has no significant performance decrease in a single camera environment. In a two camera environment, the precision is only reduced by the increased photon shot noise from the second illumination source
Granulocyte colony-stimulating factors for febrile neutropenia prophylaxis: systematic review and mixed method treatment comparison
Background
This study assesses the efficacy of three granulocyte colony-stimulating factors (G-CSFs; pegfilgrastim, filgrastim and lenograstim) in preventing febrile neutropenia (FN).
Methods
A systematic review was undertaken. Head-to-head studies were combined using direct meta-analyses. In addition, an indirect Bayesian mixed treatment comparison (MTC) was undertaken to facilitate comparison between G-CSFs where there were no direct trials, and to allow data from all trials to be synthesised into a coherent set of results.
Results
The review identified the following studies comparing G-CSF prophylaxis to no primary G-CSF prophylaxis: 5 studies of pegfilgrastim, 9 studies of filgrastim and 5 studies of lenograstim. In addition, 5 studies were identified comparing pegfilgrastim to filgrastim. The two synthesis methods (meta-analysis and MTC) demonstrated that all three G-CSFs significantly reduced FN rate. Pegfilgrastim reduced FN rate to a greater extent than filgrastim (significantly in the head-to-head meta-analysis and in the MTC of all studies, and not quite significantly when the MTC was restricted to RCTs only). In the absence of direct trials, the MTC gave an 80-86% probability that pegfilgrastim is superior to lenograstim in preventing FN, and a 71-72% probability that lenograstim is superior to filgrastim.
Conclusions
Prophylaxis with G-CSFs significantly reduces FN rate. A head-to-head meta-analysis shows pegfilgrastim to be significantly superior to filgrastim in preventing FN events, while an MTC demonstrates that pegfilgrastim is likely to be superior to lenograstim
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