3,351 research outputs found

    Five-year financial analysis of two commercial farms converting to organic: 2000-2005

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    The financial performance including input and output costs were analysed for two commercial Scottish farms converting to organic production. A comparative analysis for a five year period is provided using data from the Scottish Farm Accounts scheme, and demonstrates that both conversions had positive financial outcomes. Both farms applied strategic changes to their businesses

    Duality and Pro-Spectra

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    Cofiltered diagrams of spectra, also called pro-spectra, have arisen in diverse areas, and to date have been treated in an ad hoc manner. The purpose of this paper is to systematically develop a homotopy theory of pro-spectra and to study its relation to the usual homotopy theory of spectra, as a foundation for future applications. The surprising result we find is that our homotopy theory of pro-spectra is Quillen equivalent to the opposite of the homotopy theory of spectra. This provides a convenient duality theory for all spectra, extending the classical notion of Spanier-Whitehead duality which works well only for finite spectra. Roughly speaking, the new duality functor takes a spectrum to the cofiltered diagram of the Spanier-Whitehead duals of its finite subcomplexes. In the other direction, the duality functor takes a cofiltered diagram of spectra to the filtered colimit of the Spanier-Whitehead duals of the spectra in the diagram. We prove the equivalence of homotopy theories by showing that both are equivalent to the category of ind-spectra (filtered diagrams of spectra). To construct our new homotopy theories, we prove a general existence theorem for colocalization model structures generalizing known results for cofibrantly generated model categories.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol4/agt-4-34.abs.htm

    Mechanical strength and thermophysical properties of PM212: A high temperature self-lubricating powder metallurgy composite

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    A powder metallurgy composite, PM212, composed of metal bonded chromium carbide and solid lubricants is shown to be self-lubricating to a maximum application temperature of 900 C. The high temperature compressive strength, tensile strength, thermal expansion and thermal conductivity data needed to design PM212 sliding contact bearings and seals are reported for sintered and isostatically pressed (HIPed) versions of PM212. Other properties presented are room temperature density, hardness, and elastic modulus. In general, both versions appear to have adequate strength to be considered as sliding contact bearing materials, but the HIPed version, which is fully dense, is much stronger than the sintered version which contains about 20 percent pore volume. The sintered material is less costly to make, but the HIPed version is better where high compressive strength is important

    Insulator-to-Metal Transition in Selenium-Hyperdoped Silicon: Observation and Origin

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    Hyperdoping has emerged as a promising method for designing semiconductors with unique optical and electronic properties, although such properties currently lack a clear microscopic explanation. Combining computational and experimental evidence, we probe the origin of sub-band gap optical absorption and metallicity in Se-hyperdoped Si. We show that sub-band gap absorption arises from direct defect-to-conduction band transitions rather than free carrier absorption. Density functional theory predicts the Se-induced insulator-to-metal transition arises from merging of defect and conduction bands, at a concentration in excellent agreement with experiment. Quantum Monte Carlo calculations confirm the critical concentration, demonstrate that correlation is important to describing the transition accurately, and suggest that it is a classic impurity-driven Mott transition.Comment: 5 pages, 3 figures (PRL formatted

    Management of serology negative human hepatic hydatidosis (caused by Echinococcus granulosus) in a young woman from Bangladesh in a resource-rich setting: A case report

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    Human cystic echinococcosis (hydatidosis) is a parasitic zoonosis with almost complete worldwide distribution. Echinococcus granulosus, the dog tapeworm, causes hydatidosis which accounts for 95% of human echinococcosis. Although this tapeworm is found in dogs as a definitive host and a number of intermediate hosts, humans are often infected from close contact with infected dogs. Humans are not part of the parasitic lifecycle and serve as accidental hosts. Hydatidosis is an important consideration in the differential diagnosis of hepatic cysts in individuals from endemic areas. Clinicians should be aware of the long incubation period, the high frequency of negative serological tests, and the possibility of intraoperative evaluations of the cyst aspirate being non-diagnostic. We describe a case of serology negative hydatidosis that came to medical attention as an incidental finding in a young woman from Bangladesh. The patient underwent imaging and was then started on albendazole. After several weeks of albendazole, the cyst was punctured, aspirated, injected with hypertonic saline, re-aspirated, and then fully excised. Diagnosis was confirmed by microscopic evaluation of the cyst aspirate. Serological tests for hydatidosis may be negative in patients with early disease and thus should not be used to rule out this disease. Consideration of this diagnosis allows clinicians to avoid the catastrophic spillage of cystic contents risking an anaphylactic reaction, which might prove fatal. Despite World Health Organization hydatidosis staging being based on ultrasound, radiologists in resource-rich setting may prefer MRI in the management and staging of cystic echinococcosis

    Can Social Networking Be Used to Promote Engagement in Child Maltreatment Prevention Programs? Two Pilot Studies

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    Introduction: Child maltreatment is one of the United States’ most significant public health problems.In efforts to prevent maltreatment experts recommend use of Behavioral Parent Training Programs(BPTs), which focus on teaching skills that will replace and prevent maltreating behavior. eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. While there isresearch to support the effectiveness of BPTs in maltreatment prevention, the reach of such programsis still limited by several barriers, including poor retention of families in services. Recently, newtechnologies have emerged that offer innovative opportunities to improve family engagement. Thesetechnologies include smartphones and social networking; however, very little is known about thepotential of these to aid in maltreatment prevention. The primary goal of this study was to conduct 2pilot exploratory projects. Methods: The first project administered a survey to parents and providers to gather data about at-risk parents’ use of smartphones and online social networking technologies. The second project tested asocial networking-enhanced brief parenting program with 3 intervention participants and evaluatedparental responses. Results: Seventy-five percent of parents surveyed reported owning a computer that worked. Eightyninepercent of parents reported that they had reliable Internet access at home, and 67% said theyused the Internet daily. Three parents participated in the intervention with all reporting improvement in parent-child interaction skills and a positive experience participating in the social networking-enhanced SafeCare components. Conclusion: In general, findings suggest that smartphones, social networking, and Facebook, in particular, are now being used by individuals who show risk factors forma treatment. Further, themajorityof parents surveyed in this study said that they like Facebook, and all parents surveyed said that they useFacebook and have a Facebook account. As well, all saw it as a potentially beneficial supplement forfuture parents enrolling in parenting programs

    Aortic calcification and femoral bone density are independently associated with left ventricular mass in patients with chronic kidney disease

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    Background Vascular calcification and reduced bone density are prevalent in chronic kidney disease and linked to increased cardiovascular risk. The mechanism is unknown. We assessed the relationship between vascular calcification, femoral bone density and left ventricular mass in patients with stage 3 non-diabetic chronic kidney disease in a cross-sectional observational study. Methodology and Principal Findings A total of 120 patients were recruited (54% male, mean age 55±14 years, mean glomerular filtration rate 50±13 ml/min/1.73 m2). Abdominal aortic calcification was assessed using lateral lumbar spine radiography and was present in 48%. Mean femoral Z-score measured using dual energy x-ray absorptiometry was 0.60±1.06. Cardiovascular magnetic resonance imaging was used to determine left ventricular mass. One patient had left ventricular hypertrophy. Subjects with aortic calcification had higher left ventricular mass compared to those without (56±16 vs. 48±12 g/m2, P = 0.002), as did patients with femoral Z-scores below zero (56±15 vs. 49±13 g/m2, P = 0.01). In univariate analysis presence of aortic calcification correlated with left ventricular mass (r = 0.32, P = 0.001); mean femoral Z-score inversely correlated with left ventricular mass (r = −0.28, P = 0.004). In a multivariate regression model that included presence of aortic calcification, mean femoral Z-score, gender and 24-hour systolic blood pressure, 46% of the variability in left ventricular mass was explained (P<0.001). Conclusions In patients with stage 3 non-diabetic chronic kidney disease, lower mean femoral Z-score and presence of aortic calcification are independently associated with increased left ventricular mass. Further research exploring the pathophysiology that underlies these relationships is warranted
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