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Biomedical subjects

G Mukherjee

Publications and source records attributed to G Mukherjee.

At least 19 recordsLinked to original sources
PubMed2006

Weighted scale-free networks in Euclidean space using local selection rule.

A spatial scale-free network is introduced and studied, whose motivation originated in the growing Internet as well as airport networks. We argue that in these real-world networks a new node necessarily selects one of its neighboring local nodes for connection and is not controlled by preferential attachment as in the Barabási-Albert (BA) model. This observation is mimicked in our model where the nodes pop up at randomly located positions in the Euclidean space and are connected to one end of the nearest link. In spite of this crucial difference it is observed that the leading behavior of our network is like that of the BA model. Defining the link weight as an algebraic power of its Euclidean length, the weight distribution and the nonlinear dependence of the nodal strength on the degree are analytically calculated. It is claimed that a power law decay of the link weights with time ensures such nonlinear behavior. Switching off the Euclidean space from the same model yields a much simpler definition of the BA model where numerical effort grows linearly with N.

Journal Article↗
PubMed2006

Purification, characterization, and antifungal activity of chitinase from Streptomyces venezuelae P10.

Streptomyces venezuelae P(10) could produce extracellular chitinase in a medium containing 0.6% colloidal chitin that was fermented for 96 hours at 30 degrees C. The enzyme was purified to apparent homogeneity with 80% saturation of ammonium sulfate as shown by chitin affinity chromatography and DEAE-cellulose anion-exchange chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the enzyme showed a molecular weight of 66 kDa. The chitinase was characterized, and antifungal activity was observed against phytopathogens. Also, the first 15 N-terminal amino-acid residues of the chitinase were determined. The chitin hydrolysed products were N-acetylglucosamine and N, N'-diacetylchitobiose.

Antifungal Agents↗
PubMed2006

K isomers in 254No: probing single-particle energies and pairing strengths in the heaviest nuclei.

We have identified two isomers in 254No, built on two- and four-quasiparticle excitations, with quantum numbers K pi = 8- and (14+), as well as a low-energy 2-quasiparticle Kpi = 3+ state. The occurrence of isomers establishes that K is a good quantum number and therefore that the nucleus has an axial prolate shape. The 2-quasiparticle states probe the energies of the proton levels that govern the stability of superheavy nuclei, test 2-quasiparticle energies from theory, and thereby check their predictions of magic gaps.

Journal Article↗
PubMed2006

Ferulic acid esterase production by Streptomyces sp.

Studies were carried out on ferulic acid esterase production using a culture of Streptomyces S10. In optimized condition, enzyme yield was 2.0 mU/ml in MBS medium, containing 1.5% de-starched wheat bran at 30 degrees C and initial pH 6.5 under agitated submerged culture.

Carboxylic Ester Hydrolases↗
PubMed2005

Evidence for nontermination of rotational bands in 74Kr.

Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max).

Journal Article↗
PubMed2005

Phase transition in a directed traffic flow network.

The generic feature of traffic in a network of flowing electronic data packets is a phase transition from a stationary free-flow phase to a continuously growing congested nonstationary phase. In the most simple network of directed oriented square lattice we have been able to observe all crucial features of such flow systems having nontrivial critical behavior near the critical point of transition. The network here is in the shape of a square lattice and data packets are randomly posted with a rate rho at one side of the lattice. Each packet executes a directed diffusive motion toward the opposite boundary where it is delivered. Packets accumulated at a particular node form a queue and a maximum of m such packets randomly jump out of this node at every time step to its neighbors on a first-in-first-out basis. The phase transition occurs at rho(c) = m. The distribution of travel times through the system is found to have a log-normal behavior and the power spectrum of the load time series shows 1/f-like noise similar to the scenario of Internet traffic.

Journal Article↗
PubMed2005

ArrayExpress--a public repository for microarray gene expression data at the EBI.

ArrayExpress is a public repository for microarray data that supports the MIAME (Minimum Information About a Microarray Experiment) requirements and stores well-annotated raw and normalized data. As of November 2004, ArrayExpress contains data from approximately 12,000 hybridizations covering 35 species. Data can be submitted online or directly from local databases or LIMS in a standard format, and password-protected access to prepublication data is provided for reviewers and authors. The data can be retrieved by accession number or queried by various parameters such as species, author and array platform. A facility to query experiments by gene and sample properties is provided for a growing subset of curated data that is loaded in to the ArrayExpress data warehouse. Data can be visualized and analysed using Expression Profiler, the integrated data analysis tool. ArrayExpress is available at http://www.ebi.ac.uk/arrayexpress.

Animals↗
PubMed2004

Scale-free network on a vertical plane.

A scale-free network is grown in the Euclidean space with a global directional bias. On a vertical plane, nodes are introduced at unit rate at randomly selected points and a node is allowed to be connected only to the subset of nodes which are below it using the attachment probability, pi(i)(t) approximately k(i)(t)l(alpha). Our numerical results indicate that the directed scale-free network for alpha=0 belongs to a different universality class compared to the isotropic scale-free network. For alpha - infinity. The link length distribution is calculated analytically for all values of alpha.

Journal Article↗
PubMed2004

Arm-crank propelled three-wheeled chair: physiological evaluation of the propulsion using one arm and both arm patterns.

Disabled people in India frequently use the arm-crank propelled three-wheeled chair (ACWC) for outdoor transportation. Two models of these chairs are commercially available: one is powered by cranking using one arm (ACWC-1) and the other uses both arms (ACWC-2). The purpose of the study was to compare the efficiency of the two types of propulsion with respect to the standard physiological responses and, consequent upon the findings, to recommend the use of a suitable one. The energetics of locomotion of the users at their freely chosen speed (FCS) were measured and compared with changes in the physiological parameters in the within-subject groups. The study was conducted in outdoor settings to simulate the actual locomotive conditions encountered by the users in their practical life. 14 males, who had been regular and proficient users of both propulsion systems for more than last six years and who had a history of paraplegia (below the 10th thoracic vertebra, n=11) and poliomyelitis (n=3) participated in the study. The subjects were required to propel the test chair (a combination of both the propulsion systems built in a single model) on an oval track of 358 m circumference at their FCS for 5 min; ambulatory data were collected during last 3 min of exercise and averaged. The FCS (m/min), heart rates (bpm) and oxygen uptake (l/min) were measured. Physiological cost index (b/m) oxygen consumption (ml/kg/min), oxygen cost (ml/kg/m) and net locomotor energy cost (kcal/kg/km) of the two sets of observations were derived and compared using a t-test for the paired observations. The FCS was significantly higher and the physiological parameters were lower with the ACWC-2 than with ACWC-1, except for heart rate and oxygen consumption, where the difference was not significant . It is concluded that two-arm use is more efficient and less physically demanding than one-arm use in the arm-crank propulsion system and that the former is more suitable for efficient ambulation.

Adult↗
PubMed2004

Characterization and identification of chitinase producing Streptomyces venezuelae P10.

In an attempt to isolate chitinase producers from soil, a streptomycete strain was found potent using natural chitin as the substrate. Chitinolytic activity was tested directly on agar plates, also with crude enzyme. Chitinase assay showed that the isolate could produce 0.8 U/ml of the enzyme. The morphological, cultural, physiological and biochemical characters of the isolate P10 were studied, and identified as Streptomyces venezuelae P10.

Acetylglucosamine↗
PubMed2003

Determination of the 8B neutrino spectrum.

We have measured the total energy of the alpha particles following the beta decay of 8B by implanting 8B into a planar silicon surface barrier detector. Calibration was performed using alpha particles following the beta decay of 20Na, similarly implanted. The alpha spectrum is used to infer the 8B neutrino spectrum which is an important input in the interpretation of experiments that detect energetic neutrinos from the Sun. The alpha spectrum reported here is in disagreement with the previous best measurement which used two detectors in coincidence.

Journal Article↗
PubMed2003

Multiphonon vibrations at high angular momentum in 182 Os.

Evidence is presented for multiphonon excitations based on a high-spin (25 Planck) intrinsic state in the deformed nucleus 182 Os. Angular momentum generation by this mode competes with collective rotation. The experimental data are compared with tilted-axis cranking calculations, supporting the vibrational interpretation. However, the lower experimental energies provide evidence that more complex interactions of states are playing a role.

Journal Article↗
PubMed2003

Overexpression of Skp2 in carcinoma of the cervix does not correlate inversely with p27 expression.

S-phase kinase associated protein 2 (Skp2) is a member of the F-box family of substrate recognition subunits of SCF-ubiquitin ligase complexes and controls progression from G(1)-S-phase by targeting cell cycle regulators such as p21 and p27. Its locus is at 5p13, a region of frequent amplification in several cancers including carcinoma of the cervix (CaCx). Overexpression of Skp2 has been observed in many cancers of an advanced stage. We examine the expression of Skp2 in 42 invasive CaCx and its correlation with tumour differentiation state and p27 expression. Using immunohistochemistry we found increased nuclear expression of Skp2 in 55% of invasive CaCx cases analysed. It is significant that poorly differentiated tumours invariably exhibit high Skp2 expression (>40% positive nuclei), whereas well-differentiated tumours express Skp2 at a lower level (<20% positive nuclei). Skp2 expression in normal cervical epithelia is <10% (positive nuclei). Increased Skp2 protein levels did not correlate inversely with p27 expression. Our data suggest that Skp2 may contribute to the progression of CaCx, however, unlike non-human papillomavirus (HPV) containing tumours, p27 is unlikely to be the major target protein contributing to malignant progression. The high prevalence of HPV types in CaCx may circumvent the need for Skp2 to eliminate p27.

Cell Cycle↗
PubMed2003

Small-world properties of the Indian railway network.

Structural properties of the Indian railway network is studied in the light of recent investigations of the scaling properties of different complex networks. Stations are considered as "nodes" and an arbitrary pair of stations is said to be connected by a "link" when at least one train stops at both stations. Rigorous analysis of the existing data shows that the Indian railway network displays small-world properties. We define and estimate several other quantities associated with this network.

Journal Article↗
PubMed2003

Quasistatic scale-free networks.

A network is formed using the N sites of a one-dimensional lattice in the shape of a ring as nodes and each node with the initial degree k(in)=2. N links are then introduced to this network, each link starts from a distinct node, the other end being connected to any other node with degree k randomly selected with an attachment probability proportional to k(alpha). Tuning the control parameter alpha, we observe a transition where the average degree of the largest node changes its variation from N0 to N at a specific transition point of alpha(c). The network is scale free, i.e., the nodal degree distribution has a power law decay for alpha> or = alpha(c).

Journal Article↗
PubMed2002

Submandibular synovial sarcoma with t(X;18) and synovial sarcoma of the toe with additional cytogenetic abnormalities: presentation of two cases and review of the literature.

We report cytogenetic findings from fine-needle aspiration samples of two synovial sarcoma patients. The cases are of interest because (1) one case is of a rare site (submandibular region) of the head and neck, and (2) the other is a patient with synovial sarcoma of the toe showing additional cytogenetic abnormalities along with t(X;18). The literature of this tumor is reviewed.

Adult↗