12,808 research outputs found

    Berkeley on Evil

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    This essay consists of two parts. Part I offers an explanation of Berkeley's understanding of the relationship between materialism and evil. Berkeley regards materialism as the chief instrumental cause of evil in the world. It is the belief in matter that encourages us to believe that God is not immediately, intimately present in every aspect of our life. Immaterialism, by contrast, makes God's immediate presence vivid and thereby serves to undermine the motivation to vice. Part II locates Berkeley's view on matter and evil within the Christian Neoplatonic tradition. I compare Plotinus' minimalist approach to matter and his identification of matter with evil to Berkeley's eliminitivism about matter and his corresponding identification of materialism as the chief source of evil

    Two-dimensional photonic band-gap structures as quasi-metals

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    By considering waves that propagate out of the transverse plane, we show that common high index materials (eg GaAs) with a 2D array of air holes can act in some ways like a 3D photonic band-gap structure. In particular, we describe a dielectric "quasi-metal" that reflects all propagating light incident from free space

    Hydrogen film cooling of a small hydrogen-oxygen thrust chamber and its effect on erosion rates of various ablative materials

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    An experimental investigation was conducted to determine what arrangement of film-coolant-injection orifices should be used to decrease the erosion rates of small, high temperature, high pressure ablative thrust chambers without incurring a large penalty in combustion performance. All of the film cooling was supplied through holes in a ring between the outer row of injector elements and the chamber wall. The best arrangement, which had twice the number of holes as there were outer row injection elements, was also the simplest. The performance penalties, presented as a reduction in characteristic exhaust velocity efficiency, were 0.8 and 2.8 percentage points for the 10 and 20 percent cooling flows, respectively, The best film-coolant injector was then used to obtain erosion rates for 19 ablative materials. The throat erosion rate was reduced by a factor of 2.5 with a 10 percent coolant flow. Only the more expensive silica phenolic materials had low enough erosion rates to be considered for use in the nozzle throat. However, some of the cheaper materials might qualify for use in other areas of small nozzles with large throat diameters where the higher erosion rates are more acceptable

    Composite Structure with Load Distribution Devices, and Method for Making Same

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    An improved composite structure and method for making same has been provided. The provided improved composite structure has locally strengthened areas within a reinforcement region. The locally strengthened areas within the reinforcement region have load distribution devices to redistribute load in order to (i) locally strengthen an area around damage induced by an initial momentary and direct transmitted load, and (ii) limit growth and propagation of damage induced by an initial momentary and direct transmitted load during a subsequent unbalance load. The improved composite structure reduces the impact of the fan blade out phenomenon in a weight efficient manner

    Airborne chemical sensing with mobile robots

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    Airborne chemical sensing with mobile robots has been an active research areasince the beginning of the 1990s. This article presents a review of research work in this field,including gas distribution mapping, trail guidance, and the different subtasks of gas sourcelocalisation. Due to the difficulty of modelling gas distribution in a real world environmentwith currently available simulation techniques, we focus largely on experimental work and donot consider publications that are purely based on simulations

    Two decades of external peer review of cancer care in general hospitals; the Dutch experience

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    External peer review was introduced in general hospitals in the Netherlands in 1994 to assess and improve the multidisciplinary team approach in cancer care. This paper aims to explore the value, perceived impact, and (future) role of external peer review in cancer care. Semistructured interviews were held with clinicians, oncology nurses, and managers from fifteen general hospitals that participated in three rounds of peer review over a period of 16 years. Interviewees reflected on the goals and expectations, experiences, perceived impact, and future role of external peer review. Transcriptions of the interviews were coded to discover recurrent themes. Improving clinical care and organization were the main motives for participation. Positive impact was perceived on multiple aspects of care such as shared responsibilities, internal prioritization of cancer care, improved communication, and a clear structure and position of cancer care within general hospitals. Establishing a direct relationship between the external peer review and organizational or clinical impact proved to be difficult. Criticism was raised on the content of the program being too theoretical and organization-focussed after three rounds. According to most stakeholders, external peer review can improve multidisciplinary team work in cancer care; however, the acceptance is threatened by a perceived disbalance between effort and visible clinical impact. Leaner and more clinically focused programs are needed to keep repeated peer reviews challenging and worthwhile

    Effects of Dietary Fiber and Reduced Crude Protein on Ammonia Emission from Laying-Hen Manure

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    Ammonia (NH3 ) emission is a major concern for the poultry industry. The objective of this research was to determine whether inclusion of dietary fiber and a reduced dietary CP content would decrease NH3 emission from laying-hen manure. A total of 256 Hy-Line W-36 hens were fed diets with 2 levels of CP (normal and reduced) and 4 fiber treatments in a 2 × 4 factorial arrangement. The fiber treatments included a corn and soybean meal-based control diet and diets formulated with either 10.0% corn dried distillers grains with solubles (DDGS), 7.3% wheat middlings (WM), or 4.8% soybean hulls (SH) to contribute equal amounts of additional neutral detergent fiber. The CP contents of the reduced-CP diets were approximately 1 percentage unit lower than those of the normal-CP diets. All diets were formulated on the basis of digestible amino acid content and were formulated to be isoenergetic. Fresh manure was collected such that pH, uric acid, and Kjeldahl N contents could be measured. The NH3 emission from manure was measured over 7 d by placing pooled 24-h manure samples in NH3 emission vessels. Data were analyzed by ANOVA with Dunnett’s multiple-comparisons procedure to compare results from the fiber treatments with the control, whereas the main effect of protein was used to compare the normal- and reduced-CP treatments. Dietary corn DDGS, WM, or SH lowered (P ≤ 0.01) the 7-d cumulative manure NH3 emission from 3.9 g/kg of DM manure for the control to 1.9, 2.1, and 2.3 g/kg of DM manure, respectively, and lowered (P \u3c 0.05) the daily NH3 emission rate. Results of this study showed that dietary inclusion of 10.0% corn DDGS, 7.3% WM, or 4.8% SH lowered NH3 emission from laying-hen manure; however, reducing the CP content by 1 percentage unit had no measurable effect on NH3 emission

    Enhanced spontaneous raman scattering and gas composition analysis using a photonic crystal fiber

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    Spontaneous gas-phase Raman scattering using a hollow-core photonic bandgap fiber (HC-PBF) for both the gas cell and the Stokes light collector is reported. It was predicted that the HC-PBF configuration would yield several hundred times signal enhancement in Stokes power over a traditional free-space configuration because of increased interaction lengths and large collection angles. Predictions were verified by using nitrogen Stokes signals. The utility of this system was demonstrated by measuring the Raman signals as functions of concentration for major species in natural gas. This allowed photomultiplier-based measurements of natural gas species in relatively short integration times, measurements that were previously difficult with other systems. © 2008 Optical Society of America
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