989 resultados para bacterial diversity
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AIMS: To investigate if vaginal application of dequalinium chloride (DQC, Fluomizin®) is as effective as vaginal clindamycin (CLM) in the treatment of bacterial vaginosis (BV). METHODS: This was a multinational, multicenter, single-blind, randomized trial in 15 centers, including 321 women. They were randomized to either vaginal DQC tablets or vaginal CLM cream. Follow-up visits were 1 week and 1 month after treatment. Clinical cure based on Amsel's criteria was the primary outcome. Secondary outcomes were rate of treatment failures and recurrences, incidence of post-treatment vulvovaginal candidosis (VVC), lactobacillary grade (LBG), total symptom score (TSC), and safety. RESULTS: Cure rates with DQC (C1: 81.5%, C2: 79.5%) were as high as with CLM (C1: 78.4%, C2: 77.6%). Thus, the treatment with DQC had equal efficacy as CLM cream. A trend to less common post-treatment VVC in the DQC-treated women was observed (DQC: 2.5%, CLM: 7.7%; p = 0.06). Both treatments were well tolerated with no serious adverse events occurring. CONCLUSION: Vaginal DQC has been shown to be equally effective as CLM cream, to be well tolerated with no systemic safety concerns, and is therefore a valid alternative therapy for women with BV [ClinicalTrials.gov, Med380104, NCT01125410].
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The Chlamydiales order includes the Chlamydiaceae, Parachlamydiaceae, Waddliaceae, Simkaniaceae, Criblamydiaceae, Rhabdochlamydiaceae, Clavichlamydiaceae, and Piscichlamydiaceae families. Members of the Chlamydiales order are obligate intracellular bacteria that replicate within eukaryotic cells of different origins including humans, animals, and amoebae. Many of these bacteria are pathogens or emerging pathogens of both humans and animals, but their true diversity is largely underestimated, and their ecology remains to be investigated. Considering their potential threat on human health, it is important to expand our knowledge on the diversity of Chlamydiae, but also to define the host range colonized by these bacteria. Thus, using a new pan-Chlamydiales PCR, we analyzed the prevalence of Chlamydiales DNA in ticks and fleas, which are important vectors of several viral and bacterial infectious diseases. To conduct this study, 1340 Ixodes ricinus ticks prepared in 192 pools were collected in Switzerland and 55 other ticks belonging to different tick species and 97 fleas belonging to different flea species were harvested in Algeria. In Switzerland, the prevalence of Chlamydiales DNA in the 192 pools was equal to 28.1% (54/192) which represents an estimated prevalence in the 1340 individual ticks of between 4.0% and 28.4%. The pan-Chlamydiales qPCR was positive for 45% (25/55) of tick samples collected in Algeria. The sequencing of the positive qPCR amplicons revealed a high diversity of Chlamydiales species. Most of them belonged to the Rhabdochlamydiaceae and Parachlamydiaceae families. Thus, ticks may carry Chlamydiales and should thus be considered as possible vectors for Chlamydiales propagation to both humans and animals.
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1. Severe environmental conditions filter community species compositions, forming clines of functional diversity along environmental gradients. Here, the changes in functional diversity in ant assemblages with severe environmental conditions in the Swiss Alps were investigated. 2. Eight sites were sampled along an elevation gradient (1800-2550 m). The variation in functional diversity was analysed along an elevation gradient considering four traits: social structure (monogynous vs. polygynous), worker size, pupal development, and nest structure. 3. Ant species richness and functional diversity decreased with decreasing temperature. Species found in colder habitats tended to live in subterranean nests rather than in mounds and exhibit a polymorphism in queen number, either within or across populations. The phylogenetic diversity did not decrease at colder temperature: Formicinae and Myrmicinae occupied the full range of elevations investigated. 4. An insulation experiment indicated that mounds are more thermally insulated against the cold compared with soil. The absence of a mound-building ant from high elevations probably results from a reduction in the amount of vegetal materials provided by coniferous trees. 5. More severe abiotic conditions at higher elevations act as a filter on ant assemblages, directly through physiological tolerances to the abiotic conditions and indirectly as the vegetation necessary for nest building shifts with elevation.</list-item
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The “one-gene, one-protein” rule, coined by Beadle and Tatum, has been fundamental to molecular biology. The rule implies that the genetic complexity of an organism depends essentially on its gene number. The discovery, however, that alternative gene splicing and transcription are widespread phenomena dramatically altered our understanding of the genetic complexity of higher eukaryotic organisms; in these, a limited number of genes may potentially encode a much larger number of proteins. Here we investigate yet another phenomenon that may contribute to generate additional protein diversity. Indeed, by relying on both computational and experimental analysis, we estimate that at least 4%–5% of the tandem gene pairs in the human genome can be eventually transcribed into a single RNA sequence encoding a putative chimeric protein. While the functional significance of most of these chimeric transcripts remains to be determined, we provide strong evidence that this phenomenon does not correspond to mere technical artifacts and that it is a common mechanism with the potential of generating hundreds of additional proteins in the human genome.
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The genetic characterization of Native Mexicans is important to understand multiethnic based features influencing the medical genetics of present Mexican populations, as well as to the reconstruct the peopling of the Americas. We describe the Y-chromosome genetic diversity of 197 Native Mexicans from 11 populations and 1,044 individuals from 44 Native American populations after combining with publicly available data. We found extensive heterogeneity among Native Mexican populations and ample segregation of Q-M242* (46%) and Q-M3 (54%) haplogroups within Mexico. The northernmost sampled populations falling outside Mesoamerica (Pima and Tarahumara) showed a clear differentiation with respect to the other populations, which is in agreement with previous results from mtDNA lineages. However, our results point toward a complex genetic makeup of Native Mexicans whose maternal and paternal lineages reveal different narratives of their population history, with sex-biased continental contributions and different admixture proportions. At a continental scale, we found that Arctic populations and the northernmost groups from North America cluster together, but we did not find a clear differentiation within Mesoamerica and the rest of the continent, which coupled with the fact that the majority of individuals from Central and South American samples are restricted to the Q-M3 branch, supports the notion that most Native Americans from Mesoamerica southwards are descendants from a single wave of migration. This observation is compatible with the idea that present day Mexico might have constituted an area of transition in the diversification of paternal lineages during the colonization of the Americas.
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Mesoamerica, defined as the broad linguistic and cultural area from middle southern Mexico to Costa Rica, might have played a pivotal role during the colonization of theAmerican continent. It has been suggested that the Mesoamerican isthmus could have played an important role in severely restricting prehistorically gene flow between North and SouthAmerica. Although the Native American component has been already described in admixedMexican populations, few studies have been carried out in native Mexican populations. In thisstudy we present mitochondrial DNA (mtDNA) sequence data for the first hypervariable region (HVR-I) in 477 unrelated individuals belonging to eleven different native populations from Mexico. Almost all the Native Mexican mtDNAs could be classified into the four pan-Amerindian haplogroups (A2, B2, C1 and D1); only three of them could be allocated to the rare Native American lineage D4h3. Their haplogroup phylogenies are clearly star-like, as expected from relatively young populations that have experienced diverse episodes of genetic drift (e.g. extensive isolation, genetic drift and founder effects) and posterior population expansions. In agreement with this observation is the fact that Native Mexican populations show a high degree of heterogeneity in their patterns of haplogroup frequencies. HaplogroupX2a was absent in our samples, supporting previous observations where this clade was only detected in the American northernmost areas. The search for identical sequences in the American continent shows that, although Native Mexican populations seem to show a closer relationship to North American populations, they cannot be related to a single geographical region within the continent. Finally, we did not find significant population structure on the maternal lineages when considering the four main and distinct linguistic groups represented in our Mexican samples (Oto-Manguean, Uto-Aztecan, Tarascan, and Mayan), suggesting that genetic divergence predates linguistic diversification in Mexico.
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A contemporary perspective on the tradeoff between transmit antenna diversity andspatial multiplexing is provided. It is argued that, in the context of most modern wirelesssystems and for the operating points of interest, transmission techniques that utilizeall available spatial degrees of freedom for multiplexing outperform techniques that explicitlysacrifice spatial multiplexing for diversity. In the context of such systems, therefore,there essentially is no decision to be made between transmit antenna diversity and spatialmultiplexing in MIMO communication. Reaching this conclusion, however, requires thatthe channel and some key system features be adequately modeled and that suitable performancemetrics be adopted; failure to do so may bring about starkly different conclusions. Asa specific example, this contrast is illustrated using the 3GPP Long-Term Evolution systemdesign.
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The 2×2 MIMO profiles included in Mobile WiMAX specifications are Alamouti’s space-time code (STC) fortransmit diversity and spatial multiplexing (SM). The former hasfull diversity and the latter has full rate, but neither of them hasboth of these desired features. An alternative 2×2 STC, which is both full rate and full diversity, is the Golden code. It is the best known 2×2 STC, but it has a high decoding complexity. Recently, the attention was turned to the decoder complexity, this issue wasincluded in the STC design criteria, and different STCs wereproposed. In this paper, we first present a full-rate full-diversity2×2 STC design leading to substantially lower complexity ofthe optimum detector compared to the Golden code with only a slight performance loss. We provide the general optimized form of this STC and show that this scheme achieves the diversitymultiplexing frontier for square QAM signal constellations. Then, we present a variant of the proposed STC, which provides a further decrease in the detection complexity with a rate reduction of 25% and show that this provides an interesting trade-off between the Alamouti scheme and SM.
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Genetic diversity is essential for population survival and adaptation to changing environments. Demographic processes (e.g., bottleneck and expansion) and spatial structure (e.g., migration, number, and size of populations) are known to shape the patterns of the genetic diversity of populations. However, the impact of temporal changes in migration on genetic diversity has seldom been considered, although such events might be the norm. Indeed, during the millions of years of a species' lifetime, repeated isolation and reconnection of populations occur. Geological and climatic events alternately isolate and reconnect habitats. We analytically document the dynamics of genetic diversity after an abrupt change in migration given the mutation rate and the number and sizes of the populations. We demonstrate that during transient dynamics, genetic diversity can reach unexpectedly high values that can be maintained over thousands of generations. We discuss the consequences of such processes for the evolution of species based on standing genetic variation and how they can affect the reconstruction of a population's demographic and evolutionary history from genetic data. Our results also provide guidelines for the use of genetic data for the conservation of natural populations.
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A new graph-based construction of generalized low density codes (GLD-Tanner) with binary BCH constituents is described. The proposed family of GLD codes is optimal on block erasure channels and quasi-optimal on block fading channels. Optimality is considered in the outage probability sense. Aclassical GLD code for ergodic channels (e.g., the AWGN channel,the i.i.d. Rayleigh fading channel, and the i.i.d. binary erasure channel) is built by connecting bitnodes and subcode nodes via a unique random edge permutation. In the proposed construction of full-diversity GLD codes (referred to as root GLD), bitnodes are divided into 4 classes, subcodes are divided into 2 classes, and finally both sides of the Tanner graph are linked via 4 random edge permutations. The study focuses on non-ergodic channels with two states and can be easily extended to channels with 3 states or more.
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We show how to build full-diversity product codes under both iterative encoding and decoding over non-ergodic channels, in presence of block erasure and block fading. The concept of a rootcheck or a root subcode is introduced by generalizing the same principle recently invented for low-density parity-check codes. We also describe some channel related graphical properties of the new family of product codes, a familyreferred to as root product codes.
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Multiple-input multiple-output (MIMO) techniques have become an essential part of broadband wireless communications systems. For example, the recently developed IEEE 802.16e specifications for broadband wireless access include three MIMOprofiles employing 2×2 space-time codes (STCs), and two of these MIMO schemes are mandatory on the downlink of Mobile WiMAX systems. One of these has full rate, and the other has full diversity, but neither of them has both of the desired features. The third profile, namely, Matrix C, which is not mandatory, is both a full rate and a full diversity code, but it has a high decoder complexity. Recently, the attention was turned to the decodercomplexity issue and including this in the design criteria, several full-rate STCs were proposed as alternatives to Matrix C. In this paper, we review these different alternatives and compare them to Matrix C in terms of performances and the correspondingreceiver complexities.
Resumo:
A contemporary perspective on the tradeoff between transmit antenna diversity and spatial multi-plexing is provided. It is argued that, in the context of modern cellular systems and for the operating points of interest, transmission techniques that utilize all available spatial degrees of freedom for multiplexingoutperform techniques that explicitly sacrifice spatialmultiplexing for diversity. Reaching this conclusion, however, requires that the channel and some key system features be adequately modeled; failure to do so may bring about starkly different conclusions. As a specific example, this contrast is illustrated using the 3GPP Long-Term Evolution system design.
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The ways in which the dominant cultural majority frames the educationalsystem determine perceptions of its own identity and understandings ofthe ‘other.’ In this article I take a political approach, by examining themanagement of cultural diversity within Spanish education policies, treating“education as the mirror of society”. This article analyzes Spanish challengesand policies approaches towards the management of immigrationrelated diversity in education. The main finding is that there is not one approach,but several, due to both the decentralized character of the educationsystem and the multiplicity of diversity that is at stake (i.e. language,religion, culture etc.)