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Search Results: 1 - 10 of 401657 matches for " M. Pavan "
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A geoelectrical survey above an Antarctic ice shelf
F. Merlanti,M. Pavan
Annals of Geophysics , 1998, DOI: 10.4401/ag-4340
Abstract: A geoelectrical survey was performed on the Hells Gate ice shelf (Victoria Land-Antarctic) within the framework of an integrated geophysical and glaciological research program. The resistivity profiles show a similar trend, with resistivity values ranging from about 25000 W · m to 500000 W · m. These results have been interpreted as the effect of a sharp transition from "marine ice" to "continental" ice an interpretation that is consistent with the results of surface mapping. Interpreting the Vertical Electrical Soundings (VES) is a complex process. In fact, the alternating layers of ice with different compositions and salt content generate great uncertainty relative to the corresponding electric stratigraphies. To solve these problems of equivalency, all the available constraints were used including the drilling thickness, seismic reflection profiles as well as radar profiles. The results were used to provide what is mainly a qualitative overview that is coherent with the glaciological hypotheses relative to the evolution and structure proposed by some researchers for this ice shelf.
Some considerations on the use of the geoelectric square array
F. Merlanti,M. Pavan
Annals of Geophysics , 1996, DOI: 10.4401/ag-3958
Abstract: The square array is what we may consider to be an unconventional geoelectric configuration since it is not widely used and therefore there are few examples of practical application. The purpose of this research was to verify the operating effectiveness of this configuration in terms of profile and sounding, and the significance of the set of possible measurements and derived parameters. This was also obtained by comparing the relative measurements with the most common linear arrays (Wenner, Schlumberger, tripotential). The experiment was carried out in two different zones. In the first area, corresponding to the archaeological site of Marzabotto (Bologna), the target was represented by wall remnants inserted in a substantially homogeneous medium, from an electrical point of view, and at depths that are less than those of the dimensions of the device used. At the second site, located in the valley of Landrazza (Savona), the situation was very different, with a valley section on a calcareous bedrock filled with poorly classified residual sediments. An overall analysis of the results showed that the square technique is more exhaustive than the classical linear arrangements when performing soundings. Instead, with regard to profile development, it is not as preferred since it involves a greater amount of work without generating improved information. From analysis of the experimental results, considerable doubts arose about the meaning and the use of the anisotropy coefficients and the error term as defined theoretically. These parameters turned out to be of little use with regard to the characterization of the ground anisotropy and for checking the reliability of the measurements.
Challenges in Double Beta Decay
O. Cremonesi,M. Pavan
Physics , 2013,
Abstract: After nearly 80 years since the first guess on its existence, neutrino still escapes our insight: the mass and the true nature (Majorana or Dirac) of this particle is still unknown. In the past ten years, neutrino oscillation experiments have finally provided the incontrovertible evidence that neutrinos mix and have finite masses. These results represent the strongest demonstration that the Standard Model of electroweak interactions is incomplete and that new Physics beyond it must exist. None of these experimental efforts could however shade light on some of the basic features of neutrinos. Indeed, absolute scale and ordering of the masses of the three generations as well as charge conjugation and lepton number conservation properties are still unknown. In this scenario, a unique role is played by the Neutrinoless Double Beta Decay searches: these experiments can probe lepton number conservation, investigate the Dirac/Majorana nature of the neutrinos and their absolute mass scale (hierarchy problem) with unprecedented sensitivity. Today Neutrinoless Double Beta Decay faces a new era where large scale experiments with a sensitivity approaching the so-called degenerate-hierarchy region are nearly ready to start and where the challenge for the next future is the construction of detectors characterized by a tonne-scale size and an incredibly low background, to fully probe the inverted-hierarchy region. A number of new proposed projects took up this challenge. These are based either on large expansions of the present experiments or on new ideas to improve the technical performance and/or reduce the background contributions. n this paper, a review of the most relevant ongoing experiments is given. The most relevant parameters contributing to the experimental sensitivity are discussed and a critical comparison of the future projects is proposed.
Estudio molecular de cepas argentinas de Bacillus anthracis
Pavan,M. E.; Cairó,F.;
Revista argentina de microbiolog?-a , 2007,
Abstract: bacillus anthracis is one of the most monomorphic bacteria known and epidemiological studies of this microorganism have been hampered by the lack of molecular markers. for the genotyping of fourteen argentine field strains and the vaccine strain sterne 34f2, the presence or absence of the virulence plasmids as well as vrra locus containing a variable-number tandem repeat (vntr) and presenting a polymorphism involving five variants, were analyzed. strains were isolated from cows, sheep and pigs during outbreaks occurred in buenos aires, entre ríos, santa fe and la pampa in the past fifty years. all of the field strains presented plasmids pxo1 and pxo2, except for a strain isolated from pig that only presented plasmid pxo2. all the strains and the vaccine strain belonged to the same vntr variant that was defined by sequencing the vrra locus from three of the isolates and the strain 34f2. these sequences were completely identical and corresponded to the variant vntr4. thus, the fourteen argentine b. anthracis strains studied showed great uniformity at molecular level even though they had been isolated from different mammal species within a wide time period and covering an extensive geographical area.
Estudio molecular de cepas argentinas de Bacillus anthracis Molecular study of Argentine strains of Bacillus anthracis
M. E. Pavan,F. Cairó
Revista argentina de microbiolog?-a , 2007,
Abstract: Bacillus anthracis es una de las bacterias más monomórficas conocidas y los estudios epidemiológicos de este microorganismo se han visto dificultados por la falta de marcadores moleculares. El objetivo de este trabajo fue caracterizar molecularmente catorce cepas de campo argentinas y la cepa vacunal Sterne 34F2 sobre la base del estudio del locus vrrA, que contiene una repetición en tándem de número variable (VNTR) y presenta un polimorfismo con cinco variantes. También se ha tenido en cuenta la presencia o ausencia de los plásmidos de virulencia. Las cepas fueron aisladas de vacas, ovejas y cerdos durante brotes ocurridos en Buenos Aires, Entre Ríos, Santa Fe y La Pampa durante los últimos cincuenta a os. Todas las cepas de campo presentaron los plásmidos pXO1 y pXO2, con excepción de una cepa aislada de cerdo que únicamente presentó el plásmido pXO2. Todos los aislamientos y la cepa vacunal pertenecieron a la misma variante molecular de VNTR, que se definió secuenciando el locus vrrA de tres de los aislamientos y de la cepa 34F2. Estas secuencias fueron completamente idénticas y correspondieron a la variante VNTR4; así, las catorce cepas argentinas de B. anthracis estudiadas mostraron una gran uniformidad a nivel molecular, aun cuando se habían aislado de diferentes especies de mamíferos, en un amplio período de tiempo y en una extensa zona geográfica. Bacillus anthracis is one of the most monomorphic bacteria known and epidemiological studies of this microorganism have been hampered by the lack of molecular markers. For the genotyping of fourteen Argentine field strains and the vaccine strain Sterne 34F2, the presence or absence of the virulence plasmids as well as vrrA locus containing a variable-number tandem repeat (VNTR) and presenting a polymorphism involving five variants, were analyzed. Strains were isolated from cows, sheep and pigs during outbreaks occurred in Buenos Aires, Entre Ríos, Santa Fe and La Pampa in the past fifty years. All of the field strains presented plasmids pXO1 and pXO2, except for a strain isolated from pig that only presented plasmid pXO2. All the strains and the vaccine strain belonged to the same VNTR variant that was defined by sequencing the vrrA locus from three of the isolates and the strain 34F2. These sequences were completely identical and corresponded to the variant VNTR4. Thus, the fourteen Argentine B. anthracis strains studied showed great uniformity at molecular level even though they had been isolated from different mammal species within a wide time period and covering an extensive geographical area.
Experimental Chiral Dynamics: New Opportunities with Polarized Internal Targets and Almost-Real Photon Tagging
A. M. Bernstein,M. M. Pavan
Physics , 1998,
Abstract: Experiments on pion (Goldstone Boson) photoproduction from the nucleon tests the ability to make QCD predictions at confinement scale energies. Experiments with both polarized beams and targets have the potential sensitivity to demonstrate the dynamic isospin breaking effects of the up and down quark mass difference, whereas experiments on Compton scattering from the nucleon will incisively probe its chiral structure by measuring all of the spin dependent amplitudes. These and other types of photo-induced measurements on nuclei could be possible at BLAST with the addition of an almost-real photon tagging system and a forward low energy recoil ion hodoscope.
Evaluation of world health organization grading system in estimating the severity of dengue in adults in a tertiary care centre
Pavan Kumar M,Swapna M,Smitha
Al Ameen Journal of Medical Sciences , 2012,
Abstract: Objectives: (1) To study the profile of dengue fever in patients admitted to a tertiary care centre. (2)To assess the performance of WHO classification in estimating the severity of dengue (3) To know the outcome of patients according to WHO grading for dengue fever. Background: Dengue virus infection causes a spectrum of clinical manifestations, usually classified according to the World Health Organization (WHO) grading system. We aimed to evaluate the WHO grading system in estimating the severity of dengue in adults in a tertiary centre. Methods: Our study included 88 laboratory confirmed cases of dengue infection. WHO criteria were applied to classify patients into Dengue Fever (DF), Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS).Patients were followed up with clinical and laboratory monitoring until discharge or death. We also grouped patients on the basis of whether they received significant intervention based on fluid replacement or requirements for blood transfusion. Results: Out of 88 patients, 36.3% of patients were found to have dengue fever, 56.7% with DHF, 10.2% with DSS. Plasma leakage and thrombocytopenia were significant factors in differentiating dengue from DHF, DSS. Majority of patients with DHF, DSS required interventions like fluid resuscitation and blood transfusion. Mean duration of hospital stay was longer in DHF, DSS. Conclusion: In a tertiary care centre, WHO criteria for grading of dengue can estimate the severity of dengue, helps us to segregate the patients who need aggressive management.
Differentiation of Pancreatic Ductal Epithelial Cells into Insulin Like Cell Clusters in Chronic Pancreatitis  [PDF]
Pondugala Pavan Kumar, Gaddipati Radhika, G. Venkat Rao, D. Nageshwar Reddy, M. Sasikala
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2015, DOI: 10.4236/ojemd.2015.512022
Abstract: Background/Aim: Islet regeneration in chronic pancreatitis (CP) is relevant for managing the associated loss of endocrine function. Because ductal epithelial cells were earlier demonstrated to differentiate into pancreatic endocrine mass, we evaluated their proliferation and differentiation in chronic pancreatitis. Methods: Pancreatic ducts were obtained from surgically resected pancreata of 12 patients with chronic pancreatitis and 15 control subjects. CK19 positive ductal cells were evaluated for their proliferating and differentiating abilities upon immunostaining with Ki 67 and hormone positivity for insulin and glucagon, apart from monitoring Pdx 1 expression. Results: In comparison to the controls, a greater number of proliferating pancreatic ductal epithelial cells (PDECs) were observed under conditions of CP. The increase in Pdx1 expressing PDECs (22%) and proliferating Pdx1 expressing PDECs (30%) was significant (P < 0.04). Number of cells expressing insulin/glucagon in the exocrine ducts increased significantly in CP as compared to controls (P < 0.02) andβcell mass adjacent to the ducts increased by 28%.Conclusion: Enhanced capability of PDECs to proliferate and differentiate into endocrine mass suggests that PDECs form a source of progenitors for cell based therapy in chronic pancreatitis.
Dysregulated miRNA Associated with Transcription Factors of Insulin Gene Expression in Chronic Pancreatitis  [PDF]
K. Murali Manohar, M. Sasikala, P. Pavan Kumar, G. V. Rao, D. Nageshwar Reddy
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2016, DOI: 10.4236/ojemd.2016.610026
Abstract: Background/Aim: MicroRNAs with regulatory functions in gene expression are implicated in different diseases. The present study investigated differentially expressed miRNAs that possibly influence transcription factors involved in insulin gene expression in Chronic Pancreatitis (CP) employing bioinformatics approaches. Methods: Pancreatic tissues were collected from CP patients undergoing partial pancreatectomy (n = 16) and controls (n = 15) undergoing resections for non-pancreatic malignancies. MiRNA profiles obtained using microarrays were validated by qRT-PCR. Target search involving miRWalk and TarBase as well as functional annotation employing KEGG (Kyoto encyclopedia of genes and genomes) and DAVID (Database for Annotation) databases were performed. Ingenuity pathway analysis (IPA) was used to construct networks relating miRNAs to their target genes. mRNA and proteins related to insulin gene transcription factors and hormones were evaluated by qRT-PCR and western blotting followed by confirmation upon immunofluorescent staining. Results: Microarray data revealed 10 up-regulated and 15 down-regulated miRNAs in CP as compared to controls (Log2 FC > 2). Bioinformatic analysis showed 8399 target genes and KEGG pathway analysis suggested a role for the dysregulated miRNAs in modulating cytokine signaling, fibrosis, JAK-STAT signaling and insulin synthesis. IPA analysis suggested a simplified network attributing dysregulated miRNAs to NFκB-dependent cytokine signaling. Further, associations could be noted between miRNA 200b with Maf A, 138-1 with Neuro D and 27b with FoxO1. Decreases in mRNA levels of Pdx1, Neuro D and increases of Maf A and FoxO1 transcription factors could be noted (P < 0.01) in CP. These results were confirmed by western blotting and immunofluorescence staining. Conclusion: Our results identified dysregulation of miRNAs 138-1, 27b and 200b which were found to be associated with insulin gene transcription factors Neuro D, FoxO1 and Maf A respectively.
Mechanistic Studies of Antibody-Mediated Clearance of Tau Aggregates Using an ex vivo Brain Slice Model
Pavan K. Krishnamurthy,Einar M. Sigurdsson
Frontiers in Psychiatry , 2011, DOI: 10.3389/fpsyt.2011.00059
Abstract: Recent studies have shown that immunotherapy clears amyloid beta (Aβ) plaques and reduces Aβ levels in mouse models of Alzheimer’s disease (AD), as well as in AD patients. Tangle pathology is also relevant for the neurodegeneration in AD, and our studies have shown that active immunization with an AD related phospho-tau peptide reduces aggregated tau within the brain and slows the progression of tauopathy-induced behavioral impairments. Thus, clearance of neurofibrillary tangles and/or their precursors may reduce synaptic and neuronal loss associated with AD and other tauopathies. So far the mechanisms involved in antibody-mediated clearance of tau pathology are yet to be elucidated. In this study we have used a mouse brain slice model to examine the uptake and localization of FITC labeled anti-tau antibodies. Confocal microscopy analysis showed that the FITC labeled anti-tau antibody co-stained with phosphorylated tau, had a perinuclear appearance and co-localized with markers of the endosomal/lysosomal pathway. Additionally, tau and FITC–IgG were found together in an enriched lysosome fraction. In summary, antibody-mediated clearance of intracellular tau aggregates appears to occur via the lysosomal pathway.
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