Últimos itens adicionados do Acervo: Proceedings Nature

Nature é uma das mais prestigiosas e antigas revistas científicas do mundo: sua primeira edição é de 4 de novembro de 1869. Entre as inúmeras descobertas científicas publicadas na Nature estão a dos raios X, da estrutura em dupla hélice do ADN e o buraco na camada de ozônio.

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‣ 21 Tesla Rat Heart Magnetic Resonance Microimaging by Paramagnetic Anti-Troponin Bound Polyethylene Based Iron-Oxide Nanoparticles and Image Processing

Rakesh Sharma
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
21T MR microimaging with the first use of troponin nanoparticles enhances the visualization of cardiac muscle fibers and offers technical advancement for the future. Diffusion weighting offers fiber tracking and functional analysis. Image processing offers heart probabilistic atlas and maps. http://www.ismrm.org/10/program/ELECTRONICPOSTERS.htm

‣ Finite Predation Rate: a Novel Parameter for the Quantitative Measurement of Predation Potential of Predator at Population Level

Hsin Chi; De-Fen Mou; Hossein Allahyari; Jih-Zu Yu; Yu-Bing Huang; Ta-Chi Yang; Roya Farhadi; Majid Gholizadeh
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Demography and population growth are the most important subjects of population ecology and economics. Finite and intrinsic growth rates have been used as standard parameters for describing and comparing growth potentials of populations. The predation potentials of predator populations or consumption potentials of consumer populations cannot be properly described using these growth rates alone. A standard parameter is needed for the description of the predation or consumption potential, as well as for the quantitative evaluation of a predator population in an ecosystem or biological control program. We show that the finite predation rate can be the standard parameter by linking the finite rate, the stable age-stage distribution, and the age-stage specific predation rate. The finite predation rate can be used to describe and compare the predation potentials of natural enemies used in biological control and in predicting the damage potential of different pest populations to crops.

‣ Evolution signatures in genome network properties

Rita de Almeida; Leonardo Brunnet; José Luiz Rybarczyk-Filho; Ricardo Ferreira; Jose Claudio Moreira; Mauro Castro; Rodrigo Dalmolin
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Genomes maybe organized as networks where protein-protein association plays the role of network links. The resulting networks are far from being random and their topological properties are a consequence of the underlying mechanisms for genome evolution. Considering data on protein-protein association networks from STRING database, we present experimental evidence that degree distribution is not scale free, presenting an increased probability for high degree nodes. We also show that the degree distribution approaches a scale invariant state as the number of genes in the network increases, although real genomes still present finite size effects. Based on the experimental evidence unveiled by these data analyses, we propose a simulation model for genome evolution, where genes in a network are either acquired de novo using a preferential attachment rule, or duplicated, with a duplication probability that linearly grows with gene degree and decreases with its clustering coefficient. The results show that topological distributions are better described than in previous genome evolution models. This model correctly predicts that, in order to produce protein-protein association networks with number of links and number of nodes in the observed range...

‣ Distinct cytokine patterns in Occult Hepatitis C and Chronic Hepatitis C Virus Infection

Nasser Mousa; Nashwa Abousamra; Azza Azza Abdel-Aziz; Yahia Gad; Mona Elhadidy; Mohamed Abd-elmaksoud
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Background & Aim: The immunopathogenesis of chronic hepatitis C virus (HCV) infection is a matter of great controversy. The imbalance of T-helper lymphocyte cell cytokine production was believed to play an important pathogenic role in chronic viral hepatitis. Occult hepatitis C infection is regarded as a new entity that should be considered when diagnosing patients with a liver disease of unknown origin. The aim of this study was to determine serum T-helper 1 and T-helper 2 cytokine production in patients with occult HCV infection and its role in pathogenesis versus chronic viral hepatitis C infection. Methods: Serum levels of cytokines of T-helper 1 (IL-2, IFN-[gamma]) and T-helper 2 (IL-4) were measured in 27 patients with occult HCV infection and 50 patients with chronic hepatitis C infection. Results: The levels of the T-helper 1 cytokines, IL-2 and IFN-[gamma], were highly and significantly increased in patients with chronic HCV infection as compared with occult HCV infection (p<0.001). The T-helper 2 cytokine IL-4 was highly and significantly increased in occult HCV infection as compared with chronic HCV infection (p<0.001). Necroinflammation (P<0.001) fibrosis (P<0.001) and cirrhosis (P =0.03) were significantly increased in chronic HCV than occult HCV. Conclusion: Patients with occult HCV infection exhibited distinct immunoregulatory cytokine patterns...

‣ Isolated ileal interposition in enteroendocrine L cells differentiation

Bianca Marigliani; Joao-Luiz M. C. Azevedo; Lucas P. F. F. Leal; Ismael D. C. G. Silva; Valderez B. V. Lapchick; Sang W. Han; Karina F. Neves; Linda O. A. Bernardes; Gilmara S. A. Yamaguchi; Wellington Cardia; Jose F. Borborema; Joao L. C. Azevedo; Otavi
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
INTRODUCTION: Due to the progressive nature of type 2 diabetes, its complexity and drug treatment perpetuity, there is currently a search for surgical procedures that can promote euglycemia also in non-obese patients. Diabetic patients glycemic control can be achieved by increasing the blood concentration of GLP-1, a hormone produced by L cells that are more densely concentrated in the terminal ileum. Early and extended improvement of diabetes in patients submitted to bariatric surgeries awakened the necessity of investigating the isolated ileal interposition as surgical alternative for the treatment of diabetes. The interposition of this ileal segment to a more anterior region (proximal jejunum) can promote a greater stimulation of the L cells by poorly digested food, increasing the production of GLP-1 and reflecting on glycemic control. However, in order to consolidate the ileal interposition as a surgical treatment of diabetes it is necessary that the interposed ileum keep the same differentiation rate into L cells for a long period to justify the intervention. AIMS: To investigate the isolated ileal interposition influence on the differentiation of intestinal precursor cells into enteroendocrine L cells over time. METHODS: Twelve 12-week-old male Wistar rats (Rattus norvegicus albinus) of the WAB strain (heterogeneous) will be used. All animals will receive a high-calorie...

‣ Learning to Leap: Nanotechnology's Root in Soil Science

Siddhartha Sankar Mukhopadhyay
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
Dr. Nil Ratan Dhar Memorial Lecture Soil could be perceived as a four dimensional system where a broad three dimensional structural fabric is filled by dynamic and reactive colloidal constituents. There are interconnected relationships between authegenic, neogenic and stable-phase crystallite constituents, most of which are in nano-phase, and the system seldom reaches equilibrium. Also, variations in composition, pH, and other properties make soil unique at each place. Therefore, understanding of soil system helps to develop insight into mobility and reactivity of nano-materials. The origin of nanoscience can be traced to the discovery that clay minerals were crystalline and of micrometer size. The unit cell dimensions of clay minerals are in nanometer scale in all three axes (x, y, and z). Nanoclays played a catalytic role in the synthesis of ribosome in RNA, a process that led to genesis of life on Earth. This fact makes clays the most life-compatible material in nanotechnology. Methods followed in industry (like melting materials at a high temperature) cannot be copied for agricultural nanotechnology. Yet this is no hindrance, because nanoclays obey the laws of ion exchange, adsorption-desorption, aggregation-dispersion and solubility-precipitation...

‣ In Silico Characterization of Tomato leaf curl Joydebpur virus (ToLCJV) DNA-A Proteins

Rajneesh Prajapat; Avinash Marwal; Anurag Sahu; Rajarshi Kumar Gaur
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
We retrieved six protein sequences of Tomato leaf curl Joydebpur virus (ToLCJV) DNA-A [FJ345402] from GenBank-NCBI (ACJ03821, ACJ03822, ACJ03823, ACJ03824, ACJ03825 and ACJ03826) which were used for computational modeling structure prediction. Ramachandran plot of ACJ03826-AC4 had maximum 73.3% and ACJ03822-AV1 had 71% residues in core region therefore these models cannot be placed in a good quality category. ACJ03824-AC2 had only 18.6% residues in core and 13.6% residues in disallowed regions and therefore it was the least stable protein. Verify-3D graph profile scores for selected ToLCJV proteins were greater than zero. Therefore all the verify-3D graph corresponds to an acceptable environment for the model. Findings of the present study provide a base for docking and In-Silico anti-Begomoviral compound designing.

‣ Deterministic individual-based cellular automata modelling of single species population dynamics

Lev Kalmykov; Vyacheslav Kalmykov
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Português
This presentation was created to characterise foundations of cellular automata modelling of single species population dynamics. We show models of single species population growth based on deterministic birth-death-regeneration process and demonstrate a relationship between fecundity rate and population growth rate. Our models provide mechanistic simulation of logistic-like and double logistic-like curves of population growth that is not possible in the classical Verhulst model (logistic growth model). This method is deterministic individual-based and is based on logical “if-then” statements only. As this method is bottom-up mechanistic and provides a direct visual insight into dynamics of complex systems, we used it to study mechanisms of interspecific competition in further experiments.

‣ Historical temporal trends in monthly, seasonal, and annual mean, minimum, and maximum streamflows from the Okanagan River watershed in south-central British Columbia, Canada

Sierra Rayne; Kaya Forest
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Historical trends in monthly, seasonal, and annual mean streamflows, as well as minimum and maximum monthly streamflows, were investigated at nine hydrometric stations in the Okanagan River watershed from south-central British Columbia, Canada. Overall, mean annual streamflows in the Okanagan River watershed are not exhibiting any significant time trends. No consistent declines in monthly minimum streamflows are evident at any point during the hydrologic year. Mean monthly and monthly maximum streamflows in tributary streams to the mainstem system appear to be significantly increasing over time during the spring snowmelt period of March and April. Any temporal changes in flow patterns at the mainstem Okanagan River stations likely reflect alterations in water management strategies over time at the respective upstream dams.

‣ A Proposal of Genomic Analytical Workflow in a Bacterial Pathogen Outbreak Investigation

Hoi Shan Kwan; Chun Hang Au; Chi Keung Cheng; Man Kit Cheung; Qianli Huang; Lei Li; Wenyan Nong; Man Chun Wong
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The German Escherichia coli O104:H4 outbreak causing Hemolytic Uremic Syndrome (HUS) started in early May 2011. Conventional typing methods including serotyping, multi-locus sequence typing (MLST) and pulse-field gel electrophoresis (PFGE) seemed to yield only limited information about the causative agent. The advantages of the Genome sequencing approach are apparent compared to conventional methods. Genome sequencing and analyses with an appropriate workflow would be the new paradigm in bacterial outbreak investigation.

‣ A Biomimetic Model of the Outer Plexiform Layer by Incorporating Memristive Devices

Andras Gelencser; Themistoklis Prodromakis; Christofer Toumazou; Tamas Roska
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
In this paper we present a biorealistic model for the first part of the early vision processing by incorporating memristive nanodevices. The architecture of the proposed network is based on the organisation and functioning of the outer plexiform layer (OPL) in the vertebrate retina. We demonstrate that memristive devices are indeed a valuable building block for neuromorphic architectures, as their highly non-linear and adaptive response could be exploited for establishing ultra-dense networks with similar dynamics to their biological counterparts. We particularly show that hexagonal memristive grids can be employed for faithfully emulating the smoothing-effect occurring at the OPL for enhancing the dynamic range of the system. In addition, we employ a memristor-based thresholding scheme for detecting the edges of grayscale images, while the proposed system is also evaluated for its adaptation and fault tolerance capacity against different light or noise conditions as well as distinct device yields.

‣ Design of RNAi reagents for invertebrate model organisms and human disease vectors

Thomas Horn; Michael Boutros
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
RNAi has become an important tool to silence gene expression in a variety of organisms, in particular when classical genetic methods are missing. However, application of this method in functional studies has raised new challenges in the design of RNAi reagents in order to minimize false positive and false negative results. Since the performance of reagents can be rarely validated on a genome-wide scale, improved computational methods are required that consider experimentally derived design parameters. Here, we describe computational methods for the design of RNAi reagents for invertebrate model organisms and human disease vectors, such as Anopheles. We describe procedures on how to design short and long double-stranded RNAs for single genes, and evaluate their predicted specificity and efficiency. Using a bioinformatics pipeline we also describe how to design a genome-wide RNAi library for Anopheles gambiae.

‣ Mining SOM expression portraits: Feature selection and integrating concepts of molecular function

Henry Wirth; Martin von Bergen; Hans Binder
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Background: Self organizing maps (SOM) enable the straightforward portraying of high-dimensional data of large sample collections in terms of sample-specific images. The analysis of their texture provides so-called spot-clusters of co-expressed genes which require subsequent significance filtering and functional interpretation. We address feature selection in terms of the gene ranking problem and the interpretation of the obtained spot-related lists using concepts of molecular function. Results: Different expression scores based either on simple fold change-measures or on regularized Students t-statistics are applied to spot-related gene lists and compared with special emphasis on the error characteristics of microarray expression data. The spot-clusters are analyzed using different methods of gene set enrichment analysis with the focus on overexpression and/or overrepresentation of predefined sets of genes. Metagene-related overrepresentation of selected gene sets was mapped into the SOM images to assign gene function to different regions. Alternatively we estimated set-related overexpression profiles over all samples studied using a gene set enrichment score. It was also applied to the spot-clusters to generate lists of enriched gene sets. We used the tissue body index data set...

‣ Strong violation of the competitive exclusion principle

Lev V. Kalmykov; Vyacheslav L. Kalmykov
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Bacteria and plants are able to form population waves as a result of their consumer behaviour and propagation. A soliton-like interpenetration of colliding population waves was assumed but not proved earlier. Here we show how and why colliding population waves of trophically identical but fitness different species can interpenetrate through each other without delay. We have hypothesized and revealed here that the last mechanism provides a stable coexistence of two, three and four species, competing for the same limiting resource in the small homogeneous habitat under constant conditions and without any fitness trade-offs. We have explained the mystery of biodiversity mechanistically because (i) our models are bottom-up mechanistic, (ii) the revealed interpenetration mechanism provides strong violation of the competitive exclusion principle and (iii) we have shown that the increase in the number of competing species increases the number of cases of coexistence. Thus the principled assumptions of fitness neutrality (equivalence), competitive trade-offs and competitive niches are redundant for fundamental explanation of species richness.

‣ Preventing hereditary cancers caused by opportunistic carcinogens

Bernard Friedenson
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Objectives Previous studies reported inherited BRCA1/2 deficits can cause cancer by impairing normal protective responses. Opportunistic carcinogens can exploit these deficits by causing chronic inflammation, constant cell death and replacement in a mutagenic environment, DNA crosslinking or double strand breaks. Some of the resulting cancers may be prevented if opportunistic carcinogens are identified. Methods The literature was systematically searched for carcinogens capable of exploiting deficits in BRCA1/2 pathways. Search criteria were common exposure, available information, required BRCA1/2 pathway repairs, increased risks for any cancer, and effects on stem cells. Results Formaldehyde and acetaldehyde are closely related carcinogens and common pollutants that seem everywhere. Alcohol metabolism also produces acetaldehyde. High levels of either carcinogen overwhelm normal detoxification systems, cause inflammation, inhibit DNA repair and produce DNA cross links as critical carcinogenic lesions. Searching model system studies revealed both carcinogens activate stem cells, BRCA1/2 pathways and connected BRCA1/2 pathways to myeloid leukemia. For example, the BRCA1-BARD1 complex is required for proper nucleophosmin functions. Nucleophosmin prevents a major subset of acute myeloid leukemia (AML). Next...

‣ LogMap 2.0: towards logic-based, scalable and interactive ontology matching

Ernesto Jimenez-Ruiz; Bernardo Cuenca Grau; Yujiao Zhou
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
In this paper we present a much improved version of LogMap, a highly scalable ontology matching system with ‘built-in’ reasoning and diagnosis capabilities. LogMap 2.0 is not only more scalable and robust than its predecessor, but it also provides the necessary infrastructure for domain experts to interactively contribute to the matching process.

‣ Family values: Maternal care in rattlesnakes is more than mere attendance

Melissa Amarello; Jeffrey J. Smith; John Slone
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Parental care is important in many diverse taxa because of its positive impact on the parent's fitness. Relatively simple forms of parental care, such as female attendance and defense, which is present in many squamate reptiles, will likely provide insight into the evolution of more complex forms observed in crocodilians, birds, and mammals. Historically, observations of adult and newborn rattlesnakes in close proximity were dismissed as mere coincidence of live-birth, and only recently acknowledged as examples of parental care. In 2010, we monitored 11 pregnant Arizona black rattlesnakes (_Crotalus cerberus_): 4 solitary individuals and 2 aggregations composed of three and four individuals. We documented various forms of parental care, including active defense of neonates against potential predators. Parental care differed among solitary and aggregated females; solitary females spent more time attending and defending their progeny than individuals in aggregations. Natural variation in group size in _C. cerberus_ provides an ancestral condition in which to examine how group membership may increase fitness through parental care.

‣ Identification and Evolution of Transcription Factors in Stramenopiles

Francisco Buitrago; Silvia Restrepo; Diego Riaño-Pachón
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Transcription factors (TFs) regulate spatial and temporal gene expression by binding to DNA and either activating or repressing the action of RNA polymerases; in addition to TFs, other transcriptional regulators (TRs) participate in transcriptional modulation. With the availability of genome sequences for several organisms and computational strategies for gene functional annotation, the entire set of TFs and TRs can be identified, described, and compared between species and lineages. The diversity among Stramenopiles is striking; they range from large multicellular seaweeds to tiny unicellular species, they are present in freshwater, marine and terrestrial habitats and embrace many ecologically important algal (e.g. diatoms, brown algae, chrysophytes), and heterotrophic (e.g., Oomycetes) groups. In order to find TF and TR genes in the deduced proteomes of Stramenopiles, we followed and extended the approach developed in Perez et al. 2010. Briefly, it exploits the presence of protein domains and their combinations, in the form of boolean rules, that are specific for different families of TFs and TRs. We applied an enlarged set of rules to the deduced proteomes of 9 different Stramenopiles, identifying more than 400 different regulatory genes in each species belonging to up to 126 different gene families. The identification of this class of regulatory genes will constitute and important resource that could be exploited in gene functional characterization and evolutionary analyses. All TFs/TRs families found will be publicly released via a web database. References. Pérez-Rodríguez P...

‣ Fighting Risky Population Synchronization: Desynchronization and Stabilization in Spatially Structured Ecological Systems

Ming Luo
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Population synchronization exists ubiquitously in ecological systems, of which the underlying causes and the roles in species extinction remain a perplexing puzzle. It is generally believed that the coherence of population dynamics is detrimental and regarded as a major cause of global extinction. A central but unsolved question in ecology of great importance for conservation and biological control is how to destroy the pernicious coherent structures. Here, a top-down approach is adopted to tackle the challenge. A feedback strategy accordingly is applied to stabilize the metacommunity, i.e., to reduce excessive metapopulation fluctuations by means of introducing or removing a planned number of individuals. As a result, the feedback desynchronizes correlated population oscillations, giving rise to either complex asynchronous traveling waves or "amplitude death"; cessation of all individual population cycles. Together with the construction of corridors, my method may provide an efficient way to protect those species threatened as a result of, e.g. habitat fragmentation. I anticipate my essay provides a general mechanism against widespread harmful synchronization in physical and biological systems, for example, for developing a "brain anti-pacemaker" for neurological diseases such as Parkinson's disease and epilepsy closely linked to pathologically synchronized neuronal discharges.

‣ Screening of different species of Bacillus against broad spectrum antibiotics

Vivek Bajpai; Yamini Singh Sisodia; Pallavi Sharma; Pankaj Jain
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Sewage is waste suspended in water that is intended to flow away from a community. Sewage effluent contains a wide range of pathogenic microorganisms which may pose health hazards to the human population when they are discharged into the environment. This study is carried out to systematically examine the pathogenic microorganisms in sewage samples isolated from the Shekhawati region of Rajasthan. For this purpose a survey was carried out at the Sewage Treatment plant of the Mody Institute of Technology & Science, Laxmangarh, Sikar. In this survey we isolated 26 bacterial strains and identified them using biochemical and molecular methods. Different biochemical tests were performed during the study and in molecular identification by DNA isolation, PCR amplification using 16s rRNA primer and partial sequencing of purified product was done. The isolates were sequenced and out of 26, 10 sequences were submitted in NCBI which designated accession numbers. Out of these 10 isolates Bacillus pumilis, Bacillus subtilis and Bacillus licheniformis were taken for further studies. The growth pattern of these isolates was observed on different pH and Temperature. There is growing awareness of the need for development of new antimicrobial agents for the treatment of human...