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41.
42.
Recent years have seen a growing interest in the use of quantitative parameters for assessing the quality of research carried out at universities. In the UK, university departments are now subject to regular investigations of their research standing. As part of these investigations, a considerable amount of quantitative (as well as qualitative) information is collected from each department. This is made available to the panels appointed to assess research quality in each subject area. One question that has been raised is whether the data can be combined in some way to provide an index which can help guide the panels' deliberations. This question is looked at here via a detailed examination of the returns from four universities for the most recent (1992) research assessment exercise. The results suggest that attempts to derive an algorithm are only likely to be helpful for a limited range of subjects.  相似文献   
43.
Geotrichum candidum is a yeast-like fungus used as ripening starter in cheese making. The present study focused on chemical stress pretreatments affecting survival of G. candidum ATCC 204307 to freeze-thaw stress. Cryotolerance of G. candidum cells was induced by pretreatment with NaCl, CaCl2, or MgCl2, indicating heterologous phenotypic adaptation to freeze-thaw stress (- 20 to 25 degrees C) by osmotic stress. Furthermore, the nystatin, an antifungal compound, was shown to be a cryotolerance inducer.  相似文献   
44.
From the glasses of the binary As-S system, a large region of ternary glasses is observed in the Eu-As-S system. The thermal behaviour, the magnetic susceptibility and the Raman and infrared absorption spectra show that europium is always in the divalent state, in contrast with the ternary phase diagram in which compounds of trivalent europium are present.  相似文献   
45.
Numbers and strains of lactobacilli in some probiotic products   总被引:1,自引:0,他引:1  
The numbers and types of Lactobacillus strains in probiotic feed or food products for sale in Europe were compared with the information stated on the product labels. The labels of all 10 products gave information on the genus and species of Lactobacillus, and seven gave information on the numbers of a specified strain(s). Lactobacilli were recovered using a recently validated method, developed as part of the European Community Project SMT4 CT98-2235 for the official control of probiotic microorganisms used as feed additives. Polymerase chain reaction (PCR)-based methods were used to assess the accuracy of labelling with regard to genus and species, and pulsed-field gel electrophoresis (PFGE) was used to identify strains. Five products were mislabelled with respect to the numbers and three with respect to species of lactobacilli. In four cases, the specified strains were not detected. Four fermented milks sold under three trademarks contained the same strain, which was named differently on each label. As safety and functionality of probiotics are strain dependent, these results demonstrated the need to control lactobacilli present in commercially probiotic human food products, not only at the species but also at the strain level, to ensure their quality and protect the consumer. The usefulness of the official methods developed for animal feed additives to identify lactobacilli in probiotic foods for humans was demonstrated.  相似文献   
46.
In the year 1994, the Serengeti lion population was decimated by a canine distemper disease outbreak. Retrospective investigations showed that this host population had already been in contact with the pathogen in 1981 without any detected sign of disease. As an alternative to the virus mutation hypothesis to explain this difference in virulences observed in 1981 and 1994, we propose a novel mechanism of disease emergence based on variation in population immunity. We use a stochastic model to show that stochastic fluctuations in pathogen circulation, owing to a low probability of virus transmission from its reservoir to the target host and thereby resulting in variations in the global immunity level of the target host population, can explain the observations made in Serengeti. This mechanism may also be involved in other infectious disease emergences or re-emergences.  相似文献   
47.
Geotrichum candidum is a cheese-ripening agent with the potential to produce sulphur flavour compounds in soft cheeses. We aimed to develop an alternative test for predicting the aromatic (sulphur flavours) potential of G. candidum strains in soft cheese. Twelve strains of G. candidum with different levels of demethiolase activity (determined by a chemical method) in YEL-met (yeast extract, lactate methionine) medium were studied. We investigated cgl (cystathionine gamma lyase) gene expression after culture in three media - YEL-met, casamino acid and curd media - and then carried out sensory analysis on a Camembert cheese matrix. We found no correlation between demethiolase activity in vitro and cgl gene expression. Sensory analysis (detection of sulphur flavours) identified different aromatic profiles linked to cgl expression, but not to demethiolase activity. The RT-PCR technique described here is potentially useful for predicting the tendency of a given strain of G. candidum to develop sulphur flavours in cheese matrix. This is the first demonstration that an in vitro molecular approach could be used as a predictive test for evaluating the potential of G. candidum strains to generate sulphur compounds in situ (Camembert cheese matrix).  相似文献   
48.
Spermatogenesis and folliculogenesis involve cell–cell interactions and gene expression orchestrated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). FSH regulates the proliferation and maturation of germ cells independently and in combination with LH. In humans, the requirement for high intratesticular testosterone (T) concentration in spermatogenesis remains both a dogma and an enigma, as it greatly exceeds the requirement for androgen receptor (AR) activation. Several data have challenged this dogma. Here we report our findings on a man with mutant LH beta subunit (LHβ) that markedly reduced T production to 1–2% of normal., but despite this minimal LH stimulation, T production by scarce mature Leydig cells was sufficient to initiate and maintain complete spermatogenesis. Also, in the LH receptor (LHR) knockout (LuRKO) mice, low-dose T supplementation was able to maintain spermatogenesis. In addition, in antiandrogen-treated LuRKO mice, devoid of T action, the transgenic expression of a constitutively activating follicle stimulating hormone receptor (FSHR) mutant was able to rescue spermatogenesis and fertility. Based on rodent models, it is believed that gonadotropin-dependent follicular growth begins at the antral stage, but models of FSHR inactivation in women contradict this claim. The complete loss of FSHR function results in the complete early blockage of folliculogenesis at the primary stage, with a high density of follicles of the prepubertal type. These results should prompt the reassessment of the role of gonadotropins in spermatogenesis, folliculogenesis and therapeutic applications in human hypogonadism and infertility.  相似文献   
49.
The goal of this study was to show the usefulness of data concerning reaction time (RT) and its variability on simple psychometric items in the context of intellectual assessment of mentally retarded individuals. Two experiments compared the response time data for 2 groups of normal 7- and 9-yr-old children with data for 2 groups of mentally retarded persons whose mental ages compared to that of the children. The joint analysis of response time and variability resulted in indications regarding not only the effectiveness of information processing but the development of skills as reflected in degree of automaticity. In fact, analysis of response time variability enables the distinction of cases in which a specific skill leads to the restructuring of information processing, i.e., automation, from those which do not have such restructuring. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
50.
Cement-based materials as concrete interact with their environment. In the presence of aqueous mediums, dissolutions and precipitations of solid species composing the cement paste induce a chemical damage, which may affect the structure integrity. This paper presents a mechanical characterization of the Young modulus evolution of chemically damaged cement paste, based on a microstructural approach coupled to a reactive-transport model. The method has been successfully applied to cement pastes leached by pure water. It is concluded that the capillary porosity and its spatial distribution within the material are the parameters, which mainly rule the stiffness evolution.  相似文献   
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