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81.
This paper presents an augmented reality environment for students' improved learning, which is based on unobtrusive monitoring of the natural reading and writing process. This environment, named SESIL, is able to perform recognition of book pages and of specific elements of interest within a page, as well as to perceive interaction with actual books and pens/pencils, without requiring any special interaction device. As a result, unobtrusive, context - aware student assistance can be provided. In this way, the learning process can be enhanced during reading with the retrieval and presentation of related material and, during writing, by the provision of assistance to accomplish writing tasks whenever appropriate. The SESIL environment is evaluated in terms of robustness, accuracy and usability.  相似文献   
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83.
Like ready-to-wear clothing, medical devices come in a fixed set of sizes. While this may accommodate a large fraction of the patient population, others must either experience suboptimal results due to poor sizing or must do without the device. Although techniques have been proposed to fabricate patient-specific devices in advance of a procedure, this process is expensive and time consuming. An alternative solution that provides every patient with a tailored fit is to create devices that can be customized to the patient's anatomy as they are delivered. This paper reports an in vivo molding process in which a soft flexible photocurable stent is delivered into the trachea or bronchi over a ultraviolet (UV)-transparent balloon. The balloon is expanded such that the stent conforms to the varying cross-sectional shape of the airways. UV light is then delivered through the balloon curing the stent into its expanded conformal shape. The potential of this method is demonstrated using phantom, ex vivo, and in vivo experiments. This approach can produce stents providing equivalent airway support to those made from standard materials while providing a customized fit.  相似文献   
84.
A specifically aimed SPME/GC-MS method has been assessed in order to describe the volatile fraction of intense flavoring cheeses like Fiore Sardo PDO, a prevalent lipolytic ripening sheep cheese from Sardinia, Italy. A DVB/CAR/PDMS 50/30 μm fiber and a 3-min exposure time showed to be the best compromise between the possibility to extract compounds with a wide range of polarity and molecular mass and the need to avoid competition and displacement effects among analytes. The volatile compound profile of Fiore Sardo PDO sheep cheese was largely characterized by carboxylic acids (about 68% of the total area of recognized peaks), whereas esters (14%), ketones (9%), and alcohols (8%) represented other abundant classes of low molecular weight species. A number of low-smelling threshold trace compounds were also identified as likely contributors of aroma of the Fiore Sardo PDO cheese.  相似文献   
85.
The COVID-19 pandemic caused by SARS-CoV-2 infection is spreading at an alarming rate and has created an unprecedented health emergency around the globe. There is no effective vaccine or approved drug treatment against COVID-19 and other pathogenic coronaviruses. The development of antiviral agents is an urgent priority. Biochemical events critical to the coronavirus replication cycle provided a number of attractive targets for drug development. These include, spike protein for binding to host cell-surface receptors, proteolytic enzymes that are essential for processing polyproteins into mature viruses, and RNA-dependent RNA polymerase for RNA replication. There has been a lot of ground work for drug discovery and development against these targets. Also, high-throughput screening efforts have led to the identification of diverse lead structures, including natural product-derived molecules. This review highlights past and present drug discovery and medicinal-chemistry approaches against SARS-CoV, MERS-CoV and COVID-19 targets. The review hopes to stimulate further research and will be a useful guide to the development of effective therapies against COVID-19 and other pathogenic coronaviruses.  相似文献   
86.
The growth of Lactobacillus plantarum WCFS1 and of its ΔccpA ery mutant, WCFS1-2, was compared in batch fermentations in a complex medium at controlled pH (6.5) and temperature (30°C) with or without aeration, in order to evaluate the effect of ccpA inactivation and aeration on growth, metabolism and stress resistance. Inactivation of ccpA and, to a lesser extent, aeration, significantly affected growth, expression of proteins related to pyruvate metabolism and stress, and tolerance to heat, oxidative and cold/starvation stresses. The specific growth rate of the mutant was ca. 60% of that of the wild type strain. Inactivation of ccpA and aerobic growth significantly affected yield and production of lactic and acetic acid. Stationary phase cells were more stress tolerant than exponential phase cells with little or no effect of inactivation of ccpA or aeration. On the other hand, for exponential phase cells inactivation of ccpA impaired both heat stress and cold/starvation stress, but increased oxidative stress tolerance. For both strains, aerobically grown cells were more tolerant of stresses. Evidence for entry in a viable but non-culturable status upon prolonged exposure to cold and starvation was found. Preliminary results of a differential proteomic study further confirmed the role of ccpA in the regulation of carbohydrate catabolism and class I stress response genes and allow to gain further insight on the role of this pleiotropic regulator in metabolism and stress. This is the first study in which the impact of aerobic growth on stress tolerance of L. plantarum is evaluated. Although aerobic cultivation in batch fermentations does not improve growth it does improve stress tolerance, and may have significant technological relevance for the preservation of starter and probiotic cultures.  相似文献   
87.
In mice and other mammals, spermatogenesis is maintained by spermatogonial stem cells (SSCs), a cell population belonging to undifferentiated type A spermatogonia. In the accepted model of SSC self-renewal, Asingle (As) spermatogonia are the stem cells, whereas paired (Apaired (Apr)) and chained (Aaligned (Aal)) undifferentiated spermatogonia are committed to differentiation. This model has been recently challenged by evidence that As and chained (Apr and Aal), undifferentiated spermatogonia are heterogeneous in terms of gene expression and function. The expression profile of several markers, such as GFRA1 (the GDNF co-receptor), is heterogeneous among As, Apr and Aal spermatogonia. In this study, we have analysed and quantified the distribution of GFRA1-expressing cells within the different stages of the seminiferous epithelial cycle. We show that in all stages, GFRA1+ chained spermatogonia (Apr to Aal) are more numerous than GFRA1+ As spermatogonia. Numbers of chained GFRA1+ spermatogonia are sharply reduced in stages VII-VIII when Aal differentiate into A1 spermatogonia. GFRA1 expression is regulated by GDNF and in cultures of isolated seminiferous tubules, we found that GDNF expression and secretion by Sertoli cells is stage-dependent, being maximal in stages II-VI and decreasing thereafter. Using qRT-PCR analysis, we found that GDNF regulates the expression of genes such as Tex14, Sohlh1 and Kit (c-Kit) known to be involved in spermatogonial differentiation. Expression of Kit was upregulated by GDNF in a stage-specific manner. Our data indicate that GDNF, besides its crucial role in the self-renewal of stem cells also functions in the differentiation of chained undifferentiated spermatogonia.  相似文献   
88.
Case-control study of toenail cadmium and prostate cancer risk in Italy   总被引:2,自引:0,他引:2  
A role of cadmium exposure in prostate cancer etiology has been suggested by epidemiologic and laboratory studies, but conclusive evidence on this topic is still lacking. We investigated the relation between cadmium exposure, estimated by determining toenails cadmium levels, and prostate cancer risk in forty patients newly diagnosed with prostate cancer and fifty-eight hospital controls recruited in two provinces from southern and northern Italy. We found an excess cancer risk in subjects in the third and fourth (highest) quartiles of toenail cadmium concentration (odds ratio 1.3 and 4.7, respectively) compared with subjects in the bottom quartile. Results were basically unchanged when limiting the analysis to each province or entering toenail cadmium concentrations as continuous values in the regression model (P=0.004). Despite the limited statistical stability of the point estimates, these findings appear to support the hypothesis that cadmium exposure increases prostate cancer risk.  相似文献   
89.
90.
One of the needs of the Pelagos Sanctuary for the Conservation of Mediterranean Marine Mammals is information on critical habitats for cetaceans. This study modelled habitat use and preferences of fin whales and striped dolphins (the two most abundant species in the area) with the aim of providing this information, using sighting data collected between 1993 and 1999. The study area was divided into a 2′ latitude by 2′ longitude grid. The explanatory variables considered in the models were physiographic variables (mean, range and standard deviation of depth and slope, and distance from the nearest coastline) and remotely-sensed data (Sea Surface Temperature and Chlorophyll-a concentration). The former were calculated for each cell using GIS tools, while the latter were obtained from AVHRR and SeaWiFS sensors. Generalized Additive Models (GAMs) with multidimensional smoothers were used to model the distribution of fin whales and striped dolphins in relation to these variables, and Classification And Regression Trees were used for habitat characterization and predictive models. The GAMs were coupled with Generalized Estimating Equations (GEEs) to account for temporal autocorrelation in the errors and to help ensure model selection was reliable; the QIC statistic was used alongside GEE-based p-values. Bathymetric features were the most valuable predictors in the Pelagos Sanctuary area for both species. Sea Surface Temperature values were indicators of striped dolphin and fin whale presence, with both species showing a tendency to prefer colder waters (21–24 °C). Chl-a levels were selected by the GAM models only for striped dolphins, and with large associated uncertainty; this may be related to the relatively brief period examined (only 2 years) and/or to any functional relationship operating at a different geographical or temporal scale. The boosted classification trees however indicated an importance of Chl-a for both species. The techniques applied to this dataset proved to be valuable tools to describe habitat use and preferences of cetaceans, and the use of the remotely-sensed data can substantially improve the predictions. The results of this study will be used for assessing critical habitats within the Pelagos Sanctuary and will provide information for conservation and management in the Sanctuary.  相似文献   
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