11,519 research outputs found

    A triclinic polymorph of benzanilide : disordered molecules form hydrogen-bonded chains

    Get PDF
    Peer reviewedPublisher PD

    Effect of forward motion on engine noise

    Get PDF
    Methods used to determine a procedure for correcting static engine data for the effects of forward motion are described. Data were analyzed from airplane flyover and static-engine tests with a JT8D-109 low-bypass-ratio turbofan engine installed on a DC-9-30, with a CF6-6D high-bypass-ratio turbofan engine installed on a DC-10-10, and with a JT9D-59A high-bypass-ratio turbofan engine installed on a DC-10-40. The observed differences between the static and the flyover data bases are discussed in terms of noise generation, convective amplification, atmospheric propagation, and engine installation. The results indicate that each noise source must be adjusted separately for forward-motion and installation effects and then projected to flight conditions as a function of source-path angle, directivity angle, and acoustic range relative to the microphones on the ground

    Nearby Clumpy, Gas Rich, Star Forming Galaxies: Local Analogs of High Redshift Clumpy Galaxies

    Get PDF
    Luminous compact blue galaxies (LCBGs) have enhanced star formation rates and compact morphologies. We combine Sloan Digital Sky Survey data with HI data of 29 LCBGs at redshift z~0 to understand their nature. We find that local LCBGs have high atomic gas fractions (~50%) and star formation rates per stellar mass consistent with some high redshift star forming galaxies. Many local LCBGs also have clumpy morphologies, with clumps distributed across their disks. Although rare, these galaxies appear to be similar to the clumpy star forming galaxies commonly observed at z~1-3. Local LCBGs separate into three groups: 1. Interacting galaxies (~20%); 2. Clumpy spirals (~40%); 3. Non-clumpy, non-spirals with regular shapes and smaller effective radii and stellar masses (~40%). It seems that the method of building up a high gas fraction, which then triggers star formation, is not the same for all local LCBGs. This may lead to a dichotomy in galaxy characteristics. We consider possible gas delivery scenarios and suggest that clumpy spirals, preferentially located in clusters and with companions, are smoothly accreting gas from tidally disrupted companions and/or intracluster gas enriched by stripped satellites. Conversely, as non-clumpy galaxies are preferentially located in the field and tend to be isolated, we suggest clumpy, cold streams, which destroy galaxy disks and prevent clump formation, as a likely gas delivery mechanism for these systems. Other possibilities include smooth cold streams, a series of minor mergers, or major interactions.Comment: 22 pages, 5 figure

    Consumer perceptions and demand for biofortified sweet potato-based biscuit: The case of Akarabo golden power biscuit in Rwanda

    Get PDF
    Certain varieties of sweet potato, especially orange-fleshed, are being promoted as part of the strategy to combat vitamin A deficiency in children and pregnant mothers. However, the consumption of sweet potato is more widespread in rural households where it is mainly boiled or eaten raw. The lack of value addition excludes majority of urban and higher income consumers who consider sweet potato an inferior product. At the same time low income urban households that would be interested in consuming sweet potatoes are not able to receive regular supplies from the rural producing areas due to perishability and bulkiness of the produce. This study examines consumer perceptions and demand for value-added biofortified biscuit derived from the vitamin A-rich orange fleshed sweet potato in Rwanda. Specifically, it assesses consumer perceptions and preference for biofortified biscuit, consumer willingness to pay for biofortified biscuit and consumers’ rating of the biofortified biscuit. It uses data from 1085 consumers stratified by income levels drawn from consumers in several urban markets of Rwanda. The study finds very favorable rating of the taste, color, packaging, looks, and sweetness for the biofortified biscuit. It also finds higher willingness to pay (WTP) for the biofortified biscuit among consumers from low and low/middle income groups. However, the study finds mixed results of WTP for the biofortifed sweet potato among consumers in the high income neigborhoods. Also, contrary to expectations, the study finds no evidence that knowledge of vitamin A increases consumer rating for the biofortified biscuit, suggesting that the promotion campaigns did not change the way consumers perceive the biofortified sweet potato, perhaps due to the way the campaign was designed. The study concludes that the biofortified biscuit is currently more acceptable among the low and low/middle end income categories probably because of greater promotion at these levels. However, it has a high potential for the high amd medium income groups as evident from the high rating it received among these groups. The paper discusses the implications of these findings and suggests a need for more detailed studies and indepth quantitative analysis of consumer perceptions and WTP for orange-fleshed sweet potato.Key words: Consumers, demand, biofortified biscuits, Rwand

    COMPLETE SOLUTION OF THE XXZ-MODEL ON FINITE RINGS. DYNAMICAL STRUCTURE FACTORS AT ZERO TEMPERATURE.

    Full text link
    The finite size effects of the dynamical structure factors in the XXZ-model are studied in the euclidean time (τ)(\tau)-representation. Away from the critical momentum p=πp=\pi finite size effects turn out to be small except for the large τ\tau limit. The large finite size effects at the critical momentum p=πp=\pi signal the emergence of infrared singularities in the spectral (ω)(\omega)-representation of the dynamical structure factors.Comment: PostScript file with 12 pages + 11 figures uuencoded compresse

    Failure of Intravenous Morphine to Serve as an Effective Instrumental Reinforcer in Dopamine D2 Receptor Knock-Out Mice

    Get PDF
    The rewarding effects of opiates are thought to be mediated through dopaminergic mechanisms in the ventral tegmental area, dopamine-independent mechanisms in the nucleus accumbens, or both. The purpose of the present study was to explore the contribution of dopamine to opiate-reinforced behavior using D2 receptor knock-out mice. Wild-type, heterozygous, and D2 knock-out mice were first trained to lever press for water reinforcement and then implanted with intravenous catheters. The ability of intravenously delivered morphine to maintain lever pressing in these mice was studied under two schedules of reinforcement: a fixed ratio 4 (FR4) schedule (saline, 0.1, 0.3, or 1.0 mg/kg, per injection) and a progressive ratio (PR) schedule (1.0 mg/kg, per injection). In the wild-type and heterozygous mice, FR4 behavior maintained by morphine injections was significantly greater than behavior maintained by vehicle injections. Response rate was inversely related to injection dose and increased significantly in the wild-type and heterozygous mice when the animals were placed on the PR schedule. In contrast, the knock-out mice did not respond more for morphine than for saline and did not respond more when increased ratios were required by the PR schedule. Thus, morphine served as a positive reinforcer in the wild-type and heterozygous mice but failed to do so in the knock-out mice. Under this range of doses and response requirements, the rewarding effects of morphine appear to depend critically on an intact D2 receptor systemFil: Elmer, Greg I.. University of Maryland; Estados UnidosFil: Pieper, Jeanne O.. National Institutes of Health; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Low, Malcolm J.. Oregon Health and Sciences University; Estados UnidosFil: Grandy, David K.. Oregon Health and Sciences University; Estados UnidosFil: Wise, Roy A.. National Institutes of Health; Estados Unido

    Dysfunctional Light-Evoked Regulation of cAMP in Photoreceptors and Abnormal Retinal Adaptation in Mice Lacking Dopamine D4 Receptors

    Get PDF
    Dopamine is a retinal neuromodulator that has been implicated in many aspects of retinal physiology. Photoreceptor cells express dopamine D4 receptors that regulate cAMP metabolism. To assess the effects of dopamine on photoreceptor physiology, we examined the morphology, electrophysiology, and regulation of cAMP metabolism in mice with targeted disruption of the dopamine D4 receptor gene. Photoreceptor morphology and outer segment disc shedding after light onset were normal in D4 knock-out (D4KO) mice. Quinpirole, a dopamine D2/ D3/D4 receptor agonist, decreased cAMP synthesis in retinas of wild-type (WT) mice but not in retinas of D4KO mice. In WT retinas, the photoreceptors of which were functionally isolated by incubation in the presence of exogenous glutamate, light also suppressed cAMP synthesis. Despite the similar inhibition of cAMP synthesis, the effect of light is directly on the photoreceptors and independent of dopamine modulation, because it was unaffected by application of the D4 receptor antagonist L-745,870. Nevertheless, compared with WT retinas, basal cAMP formation was reduced in the photoreceptors of D4KO retinas, and light had no additional inhibitory effect. The results suggest that dopamine, via D4 receptors, normally modulates the cascade that couples light responses to adenylyl cyclase activity in photoreceptor cells, and the absence of this modulation results in dysfunction of the cascade. Dark-adapted electroretinogram (ERG) responses were normal in D4KO mice. However, ERG b-wave responses were greatly suppressed during both light adaptation and early stages of dark adaptation. Thus, the absence of D4 receptors affects adaptation, altering transmission of light responses from photoreceptors to inner retinal neurons. These findings indicate that dopamine D4 receptors normally play a major role in regulating photoreceptor cAMP metabolism and adaptive retinal responses to changing environmental illumination.Fil: Nir, Izhak. The University of Texas Health Science Center; Estados UnidosFil: Harrison, Joseph M.. The University of Texas Health Science Center; Estados UnidosFil: Haque, Rashidul. Emory University School of Medicine; Estados UnidosFil: Low, Malcolm J.. Oregon Health and Science University; Estados UnidosFil: Grandy, David K.. Oregon Health and Science University; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Iuvone, P. Michael. Emory University School of Medicine; Estados Unido

    Farmers’ perceptions of orange-fleshed sweetpotato: Do common beliefs about sweetpotato production and consumption really matter?

    Get PDF
    Efforts to combat vitamin A deficiency in developing countries have focused on the promotion of growing and consuming orange-fleshed sweetpotato (OFSP), among other crops. Past studies have found increased intake and even incomes among households that have been reached with information about nutritional benefits of OFSP. Consequently, efforts to scale up the production and consumption of OFSP are on-going in several African countries where vitamin A deficiency is a major problem. However, to date, few studies have systematically examined farmers’ perceptions and attitudes towards some of the attributes of OFSP. This paper interrogates some of the beliefs about the production and consumption of sweetpotato in general, and OFSP, in particular. It uses data generated using multi-stage sampling technique and involving 732 households in the Lake zone of Tanzania. The households were stratified into project participants (the intervention group) and non-participants (the control group). Within each household, data were collected from a male or female adult member (usually spouses) through personal interviews. Overall, 455 project participants and 277 non-participants were interviewed. This study uses both descriptive and exploratory factor analysis to assess some common beliefs about sweetpotato production and consumption. Contrary to the common beliefs, the study finds that sweetpotato is an important food crop to producing households, and that the common negative beliefs about sweetpotato production and consumption are not widely held. This study, therefore, recommends the need to upscale and out-scale efforts to sensitize farmers about the nutritional benefits of growing and consuming OFSP to counter the common negative beliefs about sweetpotato. In particular, educating farmers on the health effects of inadequate intake of Vitamin A and the importance of OFSP as its source can greatly influence their perceptions about OFSP. Further, there is need to increase efforts at breeding aimed at supplying the multiple desirable table and postharvest attributes of orange-fleshed sweetpotato, in addition to focusing on agronomic traits. For sub-Saharan Africa, such attributes include taste, storability of the tubers, dry matter content, and sugar content.Keywords: Sweetpotato, attributes, nutritional benefits, common beliefs, farmer perceptions, Tanzani

    Protein and cell therapy for lecithin-cholesterol acyltransferase (LCAT) deficiency

    Get PDF
    Lecithin-cholesterol acyltransferase (LCAT) is an enzyme principally secreted by the liver into the circulation where it esterifies cholesterol and plays a key role in high- density lipoprotein (HDL) metabolism. In familial and acquired (liver disease) LCAT deficiency, the failure to esterify cholesterol causes many cellular and metabolic disturbances. Here, I describe the purification of recombinant LCAT and assess two approaches to treat LCAT deficiency. Human LCAT cDNA was cloned into a selectable expression vector and used to generate a stably–transfected Chinese hamster ovary (CHO) cells secreting human LCAT tagged with 6 histidine residues. Productive clones were selected, monitoring LCAT activity by a modification of a radioactive enzymic assay for plasma, and the enzyme purified from culture medium by immobilised cobalt affinity chromatography. The pure LCAT, as judged by SDS- PAGE, was used to raise monoclonal antibodies in LCAT knockout mice for future development of a sensitive immunoassay. For therapy, I evaluated injection of pure LCAT into the peritoneal cavity of LCAT knockout mice using single and repeat dose regimes. LCAT activity was measurable in plasma post-injection and the percentage of esterified cholesterol increased, while agarose gel electrophoresis confirmed a rise in HDL levels. In a second approach, I encapsulated the recombinant CHO cells in biocompatible and semipermeable alginate-polylysine microcapsules using a syringe pump extrusion method. A study in vitro showed that, after an initial lag phase, LCAT was secreted for over 90 days with the capsules remaining intact. These microencapsulated cells were implanted into peritoneal cavities of LCAT-deficient mice. LCAT activity was detected in mice plasma one week post-implantation; the relative amount of esterified cholesterol was increased and lipoprotein profile was improved. I conclude that injection of recombinant enzyme or of encapsulated LCAT-secreting cells are feasible therapies for familial and acquired LCAT deficiency.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
    corecore