1,283 research outputs found
Professor David Audretsch: my Doktorvater
No full textWhen JP Tamvada wrote an email to David in the summer of 2004, he never expected a quick reply and invitation to come and meet him at the Max Planck Institute. In the 5 years following that first meeting, David taught the author invaluable lessons of life, exemplified ideal leadership, and shaped their scholarship
Why hasn't electronic bill presentment and payment taken off?
No full textThe delivery and payment of bills over the Internet could offer many advantages—low processing costs and enhanced marketing opportunities for billers, savings in time and postage for customers. Nevertheless, electronic billing has not found favor with potential users. A lack of coordination among billers and customers, combined with the high fixed costs of the new technology, may help account for the cool reception.Electronic funds transfers ; Electronic commerce ; Technology ; Payment systems
Absence of xenotropic murine leukaemia virus-related virus in UK patients with chronic fatigue syndrome
No full textBackground: Detection of a retrovirus, xenotropic murine leukaemia virus-related virus (XMRV), has recently been reported in 67% of patients with chronic fatigue syndrome. We have studied a total of 170 samples from chronic fatigue syndrome patients from two UK cohorts and 395 controls for evidence of XMRV infection by looking either for the presence of viral nucleic acids using quantitative PCR (limit of detection <16 viral copies) or for the presence of serological responses using a virus neutralisation assay.
Results: We have not identified XMRV DNA in any samples by PCR (0/299). Some serum samples showed XMRV neutralising activity (26/565) but only one of these positive sera came from a CFS patient. Most of the positive sera were also able to neutralise MLV particles pseudotyped with envelope proteins from other viruses, including vesicular stomatitis virus, indicating significant cross-reactivity in serological responses. Four positive samples were specific for XMRV.
Conclusions: No association between XMRV infection and CFS was observed in the samples tested, either by PCR or serological methodologies. The non-specific neutralisation observed in multiple serum samples suggests that it is unlikely that these responses were elicited by XMRV and highlights the danger of over-estimating XMRV frequency based on serological assays. In spite of this, we believe that the detection of neutralising activity that did not inhibit VSV-G pseudotyped MLV in at least four human serum samples indicates that XMRV infection may occur in the general population, although with currently uncertain outcomes
Structure, composition, and roles of the Toxoplasma gondii oocyst and sporocyst walls
No full textToxoplasma gondii is a coccidian parasite with the cat as its definitive host but any warm-blooded animal, including humans, may act as intermediate hosts. It has a worldwide distribution where it may cause acute and chronic toxoplasmosis. Infection can result from ingestion either of tissue cysts in infected meat of intermediate hosts or oocysts found in cat faeces via contaminated water or food. In this review, we highlight how the oocyst and sporocyst walls sustain the persistence and transmission of infective T. gondii parasites from terrestrial and aquatic environments to the host. We further discuss why targeting the oocyst wall structure and molecules may reduce the burden of foodborne and waterborne T. gondii infections
Selection for growth, muscling and fatness alters the maternal performance and intermediary metabolism of Merino ewes
No full textThere is growing interest in selectively breeding Merinos with higher growth and muscling and lower fatness. The effects of selection for these traits on ewe intermediary metabolism, body composition, reproduction and milk production and on lamb birthweight, survival and growth were studied in a series of experiments and analyses.
Ewes with higher genetic propensity for early growth had higher mature weight, reproductive rate, lamb birthweight, ewe milk production and lamb growth rate. Ewes with higher growth also had a higher circulating level of growth hormone during lactation.
Ewes with higher genetic propensity for muscling had a higher reproductive rate and produced lambs that were lighter at birth, but this did not result in lower lamb survival. Ewes with higher muscling maintained a higher condition score which may be at least partly attributed to a lower response to adrenaline at the level of the muscle in these higher muscled ewes. Similarly higher muscled ewes had lower growth hormone concentration in lactation which would result in lower mobilisation of tissues. In addition peripheral tissues were less responsive to insulin in high muscled ewes and blood glucose levels were also higher during the non-breeding state in high muscled ewes.
The genetic fatness of ewes was positively associated with lamb birthweight but only when nutrition was restricted suggesting that ewes with a higher genetic propensity for fatness can buffer lamb birthweight under periods of poor nutrition. Ewes with higher genetic fatness had lower circulating growth hormone and a greater response to insulin providing potential mechanisms for the observed higher fatness. Furthermore, response to adrenaline at the level of liver was greater in ewes with higher fatness suggestive of a higher capacity for gluconeogenesis. The combined results of this work suggest that actively selecting Merino ewes to have higher growth, muscling and fatness is likely to have positive reproduction and therefore economic outcomes
Passive Facebook usage undermines affective well-being: Experimental and longitudinal evidence
No full textPrior research indicates that Facebook usage predicts declines in subjective well-being over time. How does this come about? We examined this issue in 2 studies using experimental and field methods. In Study 1, cueing people in the laboratory to use Facebook passively (rather than actively) led to declines in affective well-being over time. Study 2 replicated these findings in the field using experience-sampling techniques. It also demonstrated how passive Facebook usage leads to declines in affective well-being: by increasing envy. Critically, the relationship between passive Facebook usage and changes in affective well-being remained significant when controlling for active Facebook use, non-Facebook online social network usage, and direct social interactions, highlighting the specificity of this result. These findings demonstrate that passive Facebook usage undermines affective well-being.sponsorship: This research was supported by funds provided by the University of Michigan to EK and a postdoctoral research fellowship to PV from the Fund for Scientific Research-Flanders (FWO). Author contributions: Conceived and designed Study 1: PV, DSL, JP, JB, HS, AO, OY, JJ, EK; conceived and designed Study 2: PV, DSL, JP, HS, JB, OY, JJ, EK; performed Study 1: DSL, HS, AO; performed Study 2: HS; analyzed the data: PV, DSL; wrote the article: PV, DSL, AO, EK; discussed the results and commented on the manuscript: PV, DSL, JP, HS, AO, JB, JJ, EK. (University of Michigan, Fund for Scientific Research-Flanders (FWO))status: Publishe
A Q Methodological Study of the Support Valued by Students with English as an Additional Language
No full textThis study investigated the viewpoints of students with English as an Additional Language (EAL). Specifically, I used Q methodology to highlight some of the viewpoints of learners with EAL on the strategies used by adults to support them in school. A Q set of 46 statements was produced, with each statement describing a strategy for supporting learners with EAL. The Q set was developed firstly through the use of two focus groups involving 11 students aged between 9 and 15, secondly through consultation with relevant professionals, and thirdly through a literature review. I then asked 30 participants aged between 9 and 18 to express their viewpoint through a Q sort exercise, by ranking strategies according to helpfulness. Factor analysis was used to identify viewpoints which were common to a group of participants. In the results section I present each of the emerging viewpoints as a Q sort arrangement, and also as a written description produced by interpreting the factor analysis results. The four viewpoints which emerge are discussed, along with the implications for professionals needing to provide personalised support, and also stay in touch with the viewpoints of individual students with EAL in school. It is hoped that the current research will address the need within the literature to include the voice of students with EAL in planning for their education
Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development.
No full textBACKGROUND: We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development. RESULTS: The genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements. CONCLUSIONS: Analyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution
Differences in the Long-term Progression Course of Two Cases of Pellucid-like Keratoconus: Are they the Same Condition with Different Phenotypic Presentation?
No full textWe report the long-term follow-up of two cases of untreated corneal ectasia presenting a crab claw-like sagittal and tangential topographic pattern at baseline, but without peripheral thinning. Currently, according to clinical examination, these two cases are diagnosed as pellucid-like keratoconus (PLK). The first case was a 58-year-old male who developed a true pellucid marginal degeneration (PMD) in one eye and with a nonprogressive PLK in the other eye. The second case presented was a 19-year-old male without clinical signs of ectasia at baseline that progressed to PLK with evident changes in topographic and pachymetric maps but maintaining the point of minimum corneal thickness (MCT) in the central area. The presence of two different conditions in the same patient (case 1) and the progression from inferosuperior asymmetry to the development of a crab claw-pattern (case 2) suggest that PMD, PLK, and keratoconus may be different phenotypic presentations of the same pathophysiological condition.The author David P Piñero has been supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471
Updated projections of future vCJD deaths in the UK.
No full textBACKGROUND: Past projections of the future course of the vCJD epidemic in the UK have shown considerable uncertainty, with wide confidence bounds. However, recent vCJD case data have indicated a decrease in the annual incidence of deaths over the past two years. METHODS: A detailed survival model is fitted to the 121 vCJD deaths reported by the end of 2002 stratified by age and calendar time to obtain projections of future incidence. The model is additionally fitted to recent results from a survey of appendix tissues. RESULTS: Our results show a substantial decrease in the uncertainty of the future course of the primary epidemic in the susceptible genotype (MM-homozygous at codon 129 of the prion protein gene), with a best estimate of 40 future deaths (95% prediction interval 9-540) based on fitting to the vCJD case data alone. Additional fitting of the appendix data increases these estimates (best estimate 100, 95% prediction interval 10-2,600) but remains lower than previous projections. CONCLUSIONS: The primary vCJD epidemic in the known susceptible genotype in the UK appears to be in decline
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