Statistically Locked-in Transport Through Periodic Potential Landscapes

Classical particles driven through periodically modulated potential energy landscapes are predicted to follow a Devil's staircase hierarchy of commensurate trajectories depending on the orientation of the driving force. Recent experiments on colloidal spheres flowing through arrays of optical traps do indeed reveal such a hierarchy,but not with the predicted structure. The microscopic trajectories, moreover,appear to be random, with commensurability emerging only in a statistical sense. We introduce an idealized model for periodically modulated transport in the presence of randomness that captures both the structure and statistics of such statistically locked-in states.Comment: REVTeX with EPS figures, 4 pages, 4 figure

Characterization of antimicrobial resistance mechanisms of multidrug resistant Gram negative bacterial wound infections and their clinical epidemiology from a tertiary care hospital in Karnataka, India

Background: Extended spectrum beta lactamases, AmpC and Metallo-betalactamases in GNB isolates are a common occurrence in most Indian hospitals. The presence of these antimicrobial resistance mechanisms contributes to prolonged hospital stay, poor quality of life, increased morbidity and mortality among patients with these infections. The aim of the study was to analyse the antimicrobial resistance mechanisms of multidrug resistant Gram negative bacterial wound infection and their clinical epidemiology.Methods: A prospective study was conducted for one year among 100 patients of Kasturba Medical College, Manipal admitted with MDR GNB wound infections. The antibiogram and phenotypic resistance mechanisms of the bacterial isolate from these infections were identified using phenyl boronic acid and ethyl diacetate.  The empirical therapy, specific therapy and clinical outcome of the patients were also analyzed.Results: Out of 100 study patients, 152 MDR GNB isolates were obtained.  73% patients were admitted in the surgical wards. 43% patients had diabetes. Ulcers (27%) and abscess (25%) were the most common diagnosis. Escherichia coli (39%), Klebsiella pneumoniae (24%) and Pseudomonas aeruginosa (19%) were the most common isolates. Maximum number of ESBL was seen among Enteric Gram negative bacilli (36%), MBL was seen among Pseudomonas aeruginosa and Acinetobacter species (55% each), AmpC was seen among enteric GNB (10%) and Acinetobacter species (18%). Cefaperazone sulbactam, amikacin and meropenem were the most common antibiotics given as specific therapy. Clinical response was observed among 93% patients.Conclusions: The determination of the antimicrobial resistance mechanisms of GNB isolates from wound infections plays a major role in establishing an antibiotic policy for the treatment of these infections

Digital Filters Using Identical Blocks

Improved response of non-recursive digital filters is achieved using Amplitude Change Functions (ACFs) on a prototype filter. A generalized ACF with interesting properties is suggested. Methods for achieving variable cut-off frequency and frequency transformation are explained. A modular hardware implementation is also presented

Trapping of Vibrational Energy in Crumpled Sheets

We investigate the propagation of transverse elastic waves in crumpled media. We set up the wave equation for transverse waves on a generic curved, strained surface via a Langrangian formalism and use this to study the scaling behaviour of the dispersion curves near the ridges and on the flat facets. This analysis suggests that ridges act as barriers to wave propagation and that modes in a certain frequency regime could be trapped in the facets. A simulation study of the wave propagation qualitatively supported our analysis and showed interesting effects of the ridges on wave propagation.Comment: RevTex 12 pages, 7 figures, Submitted to PR

Branching, Capping, and Severing in Dynamic Actin Structures

Branched actin networks at the leading edge of a crawling cell evolve via protein-regulated processes such as polymerization, depolymerization, capping, branching, and severing. A formulation of these processes is presented and analyzed to study steady-state network morphology. In bulk, we identify several scaling regimes in severing and branching protein concentrations and find that the coupling between severing and branching is optimally exploited for conditions {\it in vivo}. Near the leading edge, we find qualitative agreement with the {\it in vivo} morphology.Comment: 4 pages, 2 figure

Larval rearing and production of spat of the oyster Crassostrea madrasensis (Preston) in an Experimental hatchery

The Indian backwater oyster, Crassostrea madrasensis, was spawned in the laboratory at Tuticorin. The larvae were reared and the spat settled in 15-20 days. Two species of jihytoflagellates, Isochrysis galbana and Pavlova sp. were isolated from the natural environment, cultured in mass scale and given as food throughout the larval period. Early stages of the development of fertilized egg, successive stages of developing larvae, and metamorphosis to the spat have been described. The methodology of the production of cultchless spat and rearing the post-set oysters are discussed

NMR Imaging of low pressure, gas-phase transport in packed beds using hyperpolarized xenon-129

Gas-phase magnetic resonance imaging (MRI) has been used to investigate heterogeneity in mass transport in a packed bed of commercial, alumina, catalyst supports. Hyperpolarized 129Xe MRI enables study of transient diffusion for micro- scopic porous systems using xenon chemical shift to selectively image gas within the pores, and, thence, permits study of low-density, gas-phase mass-transport, such that diffusion can be studied in the Knudsen regime, and not just the molecular regime, which is the limitation with other current techniques. Knudsen-regime diffusion is common in many industrial, catalytic processes. Significantly, larger spatial variability in mass transport rates across the packed bed was found compared to techniques using only molecular diffusion. It has thus been found that that these heterogeneities arise over length-scales much larger tha

Indian edible oyster

In India pioneering attempts were made by James Hornell in 1910 in developing Oyster culture in the erstwhile Madras State. Scientific investigations were undertaken during early 70's by the Central Marine Fisheries Research Institute, at Tuticorin. The Institute has conducted R & D programmes on all aspects of Oyster farming during the last two decades, culminating in a wealth of informations on the technology of Oyster farming. The Brochure outlines various aspects of the technology of farming of the Indian Edible Oyster or the Indian Backwater Oyster Crasaostrea madrasensis (Preston} including information on biology, ecology and economics of Oyster farming

Membrane mediated motor kinetics in microtubule gliding assays.

Motor-based transport mechanisms are critical for a wide range of eukaryotic cell functions, including the transport of vesicle cargos over long distances. Our understanding of the factors that control and regulate motors when bound to a lipid substrate is however incomplete. We used microtubule gliding assays on a lipid bilayer substrate to investigate the role of membrane diffusion in kinesin-1 on/off binding kinetics and thereby transport velocity. Fluorescence imaging experiments demonstrate motor clustering on single microtubules due to membrane diffusion in the absence of ATP, followed by rapid ATP-induced dissociation during gliding. Our experimental data combined with analytical modeling show that the on/off binding kinetics of the motors are impacted by diffusion and, as a consequence, both the effective binding and unbinding rates for motors are much lower than the expected bare rates. Our results suggest that motor diffusion in the membrane can play a significant role in transport by impacting motor kinetics and can therefore function as a regulator of intracellular transport dynamics

Weak Long-Ranged Casimir Attraction in Colloidal Crystals

We investigate the influence of geometric confinement on the free energy of an idealized model for charge-stabilized colloidal suspensions. The mean-field Poisson-Boltzmann formulation for this system predicts pure repulsion among macroionic colloidal spheres. Fluctuations in the simple ions' distribution provide a mechanism for the macroions to attract each other at large separations. Although this Casimir interaction is long-ranged, it is too weak to influence colloidal crystals' dynamics.Comment: 5 pages 2 figures ReVTe