Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
59,270
result(s) for
"Sousa, A"
Sort by:
العقل البشري وظاهرة التعلم
يعرض هذا الكتاب آخر ما توصل إليه البحث العلمى والإكتشافات العلمية الحديثة فى مجال وظائف العقل البشرى. وفيه يحاول المؤلف استعراض بعض المواد المرجعية فى مجال البحث فى وظائف العقل البشرى. فيتحدث عن الأجزاء الرئيسية التى يتكون منها المخ وكيفية معالجته للمعلومات التى يستقبلها، بالإضافة إلى وظائف الذاكرة وكيفية استرجاع المعلومات فيها وكيفية انتقال أثر المعرفة لدعم عملية التعلم فى الحاضر والمستقبل.
Book
Bacteriophages benefit from generalized transduction
Temperate phages are bacterial viruses that as part of their life cycle reside in the bacterial genome as prophages. They are found in many species including most clinical strains of the human pathogens, Staphylococcus aureus and Salmonella enterica serovar Typhimurium. Previously, temperate phages were considered as only bacterial predators, but mounting evidence point to both antagonistic and mutualistic interactions with for example some temperate phages contributing to virulence by encoding virulence factors. Here we show that generalized transduction, one type of bacterial DNA transfer by phages, can create conditions where not only the recipient host but also the transducing phage benefit. With antibiotic resistance as a model trait we used individual-based models and experimental approaches to show that antibiotic susceptible cells become resistant to both antibiotics and phage by i) integrating the generalized transducing temperate phages and ii) acquiring transducing phage particles carrying antibiotic resistance genes obtained from resistant cells in the environment. This is not observed for non-generalized transducing temperate phages, which are unable to package bacterial DNA, nor for generalized transducing virulent phages that do not form lysogens. Once established, the lysogenic host and the prophage benefit from the existence of transducing particles that can shuffle bacterial genes between lysogens and for example disseminate resistance to antibiotics, a trait not encoded by the phage. This facilitates bacterial survival and leads to phage population growth. We propose that generalized transduction can function as a mutualistic trait where temperate phages cooperate with their hosts to survive in rapidly-changing environments. This implies that generalized transduction is not just an error in DNA packaging but is selected for by phages to ensure their survival.
Journal Article
Causes and Consequences of Bacteriophage Diversification via Genetic Exchanges across Lifestyles and Bacterial Taxa
Bacteriophages (phages) evolve rapidly by acquiring genes from other phages. This results in mosaic genomes. Here, we identify numerous genetic transfers between distantly related phages and aim at understanding their frequency, consequences, and the conditions favoring them. Gene flow tends to occur between phages that are enriched for recombinases, transposases, and nonhomologous end joining, suggesting that both homologous and illegitimate recombination contribute to gene flow. Phage family and host phyla are strong barriers to gene exchange, but phage lifestyle is not. Even if we observe four times more recent transfers between temperate phages than between other pairs, there is extensive gene flow between temperate and virulent phages, and between the latter. These predominantly involve virulent phages with large genomes previously classed as low gene flux, and lead to the preferential transfer of genes encoding functions involved in cell energetics, nucleotide metabolism, DNA packaging and injection, and virion assembly. Such exchanges may contribute to the observed twice larger genomes of virulent phages. We used genetic transfers, which occur upon coinfection of a host, to compare phage host range. We found that virulent phages have broader host ranges and can mediate genetic exchanges between narrow host range temperate phages infecting distant bacterial hosts, thus contributing to gene flow between virulent phages, as well as between temperate phages. This gene flow drastically expands the gene repertoires available for phage and bacterial evolution, including the transfer of functional innovations across taxa.
Journal Article
كيف يتعلم مخ ذوي الاحتياجات الخاصة
يتناول هذا الكتاب من تأليف ديفيد سوسا طبيعة تركيب المخ البشري بين الأطفال الذين يعانون من صعوبات التعلم بمختلف أنواعها، مركزا على طبيعة المشكلات الانفعالية والسلوكية التي يمكن أن تصيب هؤلاء الأطفال. ويتميز الكتاب بقسم تطبيقي تحت عنوان استراتيجيات تؤخذ في الاعتبار يختص بتوضيح التطبيقات العملية للبحوث الواردة في فصول الكتاب.
Book
Differences in handgrip strength protocols to identify sarcopenia and frailty - a systematic review
Background: Hand grip strength (HGS) is used for the diagnosis of sarcopenia and frailty. Several factors have been shown to influence HGS values during measurement. Therefore, variations in the protocols used to assess HGS, as part of the diagnosis of sarcopenia and frailty, may lead to the identification of different individuals with low HGS, introducing bias. The aim of this systematic review is to gather all the relevant studies that measured HGS to diagnose sarcopenia and frailty and to identify the differences between the protocols used. Methods: A systematic review was carried out following the recommendations of The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. PubMed and Web of Science were systematically searched, until August 16, 2016. The evidence regarding HGS measurement protocols used to diagnose sarcopenia and frailty was summarised and the most recent protocols regarding the procedure were compared. Results: From the described search 4393 articles were identified. Seventy-two studies were included in this systematic review, in which 37 referred to sarcopenia articles, 33 to frailty and two evaluated both conditions. Most studies presented limited information regarding the protocols used. Conclusions: The majority of the studies included did not describe a complete procedure of HGS measurement. The high heterogeneity between the protocols used, in sarcopenia and frailty studies, create an enormous difficulty in drawing comparative conclusions among them.
Journal Article
Comparison of five bacterial strains producing siderophores with ability to chelate iron under alkaline conditions
Iron deficiency is one of the main causes of chlorosis in plants, which leads to losses in field crops quality and yield. The use of synthetic chelates to prevent or correct iron-deficiency is not satisfactory mainly due to their poor biodegradability. The present work aimed to search suitable microorganisms to produce alternative, environment-friendly iron-chelating agents (siderophores). For this purpose, the performance of five bacteria (Azotobacter vinelandii, Bacillus megaterium, Bacillus subtilis, Pantoea allii and Rhizobium radiobacter) was evaluated, regarding siderophore production kinetics, level of siderophore production (determined by chrome azurol S, CAS method), type of siderophore produced (using Arnow and Csaky’s tests) and iron-chelating capacity at pH 9.0. All bacteria were in stationary phase at 24 h, except A. vinelandii (at 72 h) and produced the maximum siderophore amount (80–140 µmol L−1) between 24 and 48 h, with the exception of A. vinelandii (at 72 h). The analysis of culture filtrates revealed the presence of catechol-type siderophores for B. subtilis and R. radiobacter and hydroxamate-type siderophores for B. megaterium and P. allii. In the case of A. vinelandii, both siderophore-types (catechol and hydroxamates) were detected. The highest iron-chelating capacity, at pH 9.0, was obtained by B. megaterium followed by B. subtilis and A. vinelandii. Therefore, these three bacteria strains are the most promising bacteria for siderophore production and chlorosis correction under alkaline conditions.
Journal Article
Characterization of Noise Level Inside a Vehicle under Different Conditions
Vehicular acoustic noise evaluations are a concern of researchers due to health and comfort effects on humans and are fundamental for anyone interested in mitigating audio noise. This paper focuses on the evaluation of the noise level inside a vehicle by using statistical tools. First, an experimental setup was developed with microphones and a microcomputer located strategically on the car’s panel, and measurements were carried out with different conditions such as car window position, rain, traffic, and car speed. Regression analysis was performed to evaluate the similarity of the noise level from those conditions. Thus, we were able to discuss the relevance of the variables that contribute to the noise level inside a car. Finally, our results revealed that the car speed is strongly correlated to interior noise levels, suggesting the most relevant noise sources are in the vehicle itself.
Journal Article
Wide and increasing suitability for Aedes albopictus in Europe is congruent across distribution models
The Asian tiger mosquito (
Aedes albopictus
), a vector of dengue, Zika and other diseases, was introduced in Europe in the 1970s, where it is still widening its range. Spurred by public health concerns, several studies have delivered predictions of the current and future distribution of the species for this region, often with differing results. We provide the first joint analysis of these predictions, to identify consensus hotspots of high and low suitability, as well as areas with high uncertainty. The analysis focused on current and future climate conditions and was carried out for the whole of Europe and for 65 major urban areas. High consensus on current suitability was found for the northwest of the Iberian Peninsula, southern France, Italy and the coastline between the western Balkans and Greece. Most models also agree on a substantial future expansion of suitable areas into northern and eastern Europe. About 83% of urban areas are expected to become suitable in the future, in contrast with ~ 49% nowadays. Our findings show that previous research is congruent in identifying wide suitable areas for
Aedes albopictus
across Europe and in the need to effectively account for climate change in managing and preventing its future spread.
Journal Article