A Model for Quantum Stochastic Absorption in Absorbing Disordered Media

Wave propagation in coherently absorbing disordered media is generally modeled by adding a complex part to the real part of the potential. In such a case, it is already understood that the complex potential plays a duel role; it acts as an absorber as well as a reflector due to the mismatch of the phase of the real and complex parts of the potential. Although this model gives expected results for weakly absorbing disordered media, it gives unphysical results for the strong absorption regime where it causes the system to behave like a perfect reflector. To overcome this issue, we develop a model here using stochastic absorption for the modeling of absorption by "fake", or "side", channels obviating the need for a complex potential. This model of stochastic absorption eliminates the reflection that is coupled with the absorption in the complex potential model and absorption is proportional to the magnitude of the absorbing parameter. Solving the statistics of the reflection coefficient and its phase for both the models, we argue that stochastic absorption is a potentially better way of modeling absorbing disordered media.Comment: 5 pages, 4 figure

Significance of thermal fluctuations and hydrodynamic interactions in receptor-ligand mediated adhesive dynamics of a spherical particle in wall bound shear flow

The dynamics of adhesion of a spherical micro-particle to a ligand-coated wall, in shear flow, is studied using a Langevin equation that accounts for thermal fluctuations, hydrodynamic interactions and adhesive interactions. Contrary to the conventional assumption that thermal fluctuations play a negligible role at high P$\acute{e}$clet numbers, we find that for particles with low surface densities of receptors, rotational diffusion caused by fluctuations about the flow and gradient directions aids in bond formation, leading to significantly greater adhesion on average, compared to simulations where thermal fluctuations are completely ignored. The role of wall hydrodynamic interactions on the steady state motion of a particle, when the particle is close to the wall, has also been explored. At high P$\acute{e}$clet numbers, the shear induced force that arises due to the stresslet part of the Stokes dipole, plays a dominant role, reducing the particle velocity significantly, and affecting the states of motion of the particle. The coupling between the translational and rotational degrees of freedom of the particle, brought about by the presence of hydrodynamic interactions, is found to have no influence on the binding dynamics. On the other hand, the drag coefficient, which depends on the distance of the particle from the wall, plays a crucial role at low rates of bond formation. A significant difference in the effect of both the shear force and the position dependent drag force, on the states of motion of the particle, is observed when the P$\acute{e}$let number is small.Comment: The manuscript has been accepted as an article in Physical Review E Journa

Collective action for forest conservation: Does heterogeneity matter?

Community management of forests by Van Panchayats (forest councils) to meet local needs has a long history in the Indian Central Himalayas. This essay examines the effects of village-level heterogeneity in caste and land ownership, and of female membership in the Panchayats on collective action for forest conservation. There is no evidence that caste heterogeneity or female membership of the Panchayat have any effect. There is some evidence that greater equality in land ownership may enhance collective action and forest conservation in pine forests but not broadleaved forests. This is puzzling since villagers' interest in conservation is greater in broadleaved than in pine forests.

Tuberculosis - the continuing scourge of India

Epidemiological picture of tuberculosis in India is complex with wide variation in the annual risk of infection and prevalence of disease. The concentration of the disease among younger age groups makes tuberculosis a major socio-economic burden in India. The disability adjusted life years (DALYS) is estimated to be around 63 and 46 lakhs of years of life lost in men and women respectively. The burden is likely to increase with HIV epidemic with an increase of cases with dual infection, increase in morbidity and mortality due to tuberculosis. Management of drug resistant tuberculosis is a major hurdle in tuberculosis control and is a major step in cutting the chain of transmission to those with HIV infection, AIDS and immunodeficiency. Development of new therapeutic modalities to address this problem are also urgently required. Poor patient compliance has been the reason for failure of many control programmes. Operational research studies conducted by the TRC have resulted in elucidation of socio-behavioural aspects of patients’ which need further investigation for remedial measures. Studies to improve drug delivery and to measure the impact of health education and mass media on compliance are areas which need to be concentrated. Newer techniques such as DNA fingerprinting need to employed to improve knowledge of the patterns of transmission in communities. The impact of HIV infection on tuberculosis and the role of chemoprophylaxis in HIV infected individuals in high risk populations, children in close contact with newly diagnosed patients and HIV infected individuals need to be urgently explored. improved methods for diagnosis of Mycobacterium tuberculosis infection must await considerable advance in the understanding of basic immunology, mycobacterial antigenic structure and host-parasitic interaction

Needs in tuberculosis research

Tuberculosis is still a major health problem in developing countries. It is also emerging as a major infectious disease in the developed countries due to AIDS epidemic. Its pathogenesis, immunology and molecular biology are still incompletely understood. The development of new drugs to fight tuberculosis ceased over two decades ago. The variable efficacy of BCG, found in different trials, still remains an enigma. And, it is likely that its epidemiology is also different, in some aspects, in developing countries compared with the developed ones. Sometime ago, it was said that the application of current knowledge about tuberculosis was lagging so far behind its application in the field that the focus should shift from more and more research in tuberculosis. That saying appears to have lost its validity under the present circumstances, especially when the WHO has declared a global war on the “neglected epidemic”. The following horizons in different aspects of tuberculosis can be recognised in respect of research needs in tuberculosis

Gaussian approximation for finitely extensible bead-spring chains with hydrodynamic interaction

The Gaussian Approximation, proposed originally by Ottinger [J. Chem. Phys., 90 (1) : 463-473, 1989] to account for the influence of fluctuations in hydrodynamic interactions in Rouse chains, is adapted here to derive a new mean-field approximation for the FENE spring force. This "FENE-PG" force law approximately accounts for spring-force fluctuations, which are neglected in the widely used FENE-P approximation. The Gaussian Approximation for hydrodynamic interactions is combined with the FENE-P and FENE-PG spring force approximations to obtain approximate models for finitely-extensible bead-spring chains with hydrodynamic interactions. The closed set of ODE's governing the evolution of the second-moments of the configurational probability distribution in the approximate models are used to generate predictions of rheological properties in steady and unsteady shear and uniaxial extensional flows, which are found to be in good agreement with the exact results obtained with Brownian dynamics simulations. In particular, predictions of coil-stretch hysteresis are in quantitative agreement with simulations' results. Additional simplifying diagonalization-of-normal-modes assumptions are found to lead to considerable savings in computation time, without significant loss in accuracy.Comment: 26 pages, 17 figures, 2 tables, 75 numbered equations, 1 appendix with 10 numbered equations Submitted to J. Chem. Phys. on 6 February 200

DeepFuse: A Deep Unsupervised Approach for Exposure Fusion with Extreme Exposure Image Pairs

We present a novel deep learning architecture for fusing static multi-exposure images. Current multi-exposure fusion (MEF) approaches use hand-crafted features to fuse input sequence. However, the weak hand-crafted representations are not robust to varying input conditions. Moreover, they perform poorly for extreme exposure image pairs. Thus, it is highly desirable to have a method that is robust to varying input conditions and capable of handling extreme exposure without artifacts. Deep representations have known to be robust to input conditions and have shown phenomenal performance in a supervised setting. However, the stumbling block in using deep learning for MEF was the lack of sufficient training data and an oracle to provide the ground-truth for supervision. To address the above issues, we have gathered a large dataset of multi-exposure image stacks for training and to circumvent the need for ground truth images, we propose an unsupervised deep learning framework for MEF utilizing a no-reference quality metric as loss function. The proposed approach uses a novel CNN architecture trained to learn the fusion operation without reference ground truth image. The model fuses a set of common low level features extracted from each image to generate artifact-free perceptually pleasing results. We perform extensive quantitative and qualitative evaluation and show that the proposed technique outperforms existing state-of-the-art approaches for a variety of natural images.Comment: ICCV 201

Does decentralization work? Forest conservation in the Himalayas

This paper studies the effect of decentralization of management and control on forest conservation in the central Himalayas. The density of forest cover (measured with satellite images and field surveys) in forests managed by village councils is compared with that in state-managed forests and in unmanaged village commons. Geographic proximity and historical and ecological information are used to identify the effects of the three types of management regimes. Village council management does no worse, and possibly better, at conservation than state management and costs an order of magnitude less per unit area. Relative to unmanaged commons, village council management raises crown cover in broadleaved forests (the type of forest that may provide the most benefits to villagers under the rules) but not in pine forests.

Fluctuation Theorems

Fluctuation theorems, which have been developed over the past 15 years, have resulted in fundamental breakthroughs in our understanding of how irreversibility emerges from reversible dynamics, and have provided new statistical mechanical relationships for free energy changes. They describe the statistical fluctuations in time-averaged properties of many-particle systems such as fluids driven to nonequilibrium states, and provide some of the very few analytical expressions that describe nonequilibrium states. Quantitative predictions on fluctuations in small systems that are monitored over short periods can also be made, and therefore the fluctuation theorems allow thermodynamic concepts to be extended to apply to finite systems. For this reason, fluctuation theorems are anticipated to play an important role in the design of nanotechnological devices and in understanding biological processes. These theorems, their physical significance and results for experimental and model systems are discussed.Comment: A review, submitted to Annual Reviews in Physical Chemistry, July 2007 Acknowledgements corrected in revisio

Species diversity of birds in mangroves of Uran (Raigad), Navi Mumbai, Maharashtra, West coast of India

Mangroves are one of the most biologically diverse ecosystems in the world, providing shelter and feeding sites for many animal species. With continuing degradation and destruction of mangroves, there is a critical need to understand the biodiversity of the mangrove ecosystems. Birds are bio-indicators of habitat quality and are sensitive to any subtle changes takes place in the habitat. Monitoring of species diversity is a useful technique for assessing damage to the system and maintenance of good species diversity is a positive management objective. A total of 56 species of birds representing 11 orders, 29 families and 46 genera were recorded from the mangroves of Uran coast. Of the recorded species, 33.93 % belonged to Order Passeriformes, 26.79 % to Ciconiiformes, 8.93 % to Charadriiformes, 7.14 % to Anseriformes, 5.36 % each to Coraciiformes and Falconiformes, 3.57 % each to Columbiformes and Gruiformes and 1.79 % each to Cuculiformes, Pelecaniformes and Psittaciformes. Avifauna of the order Passeriformes is dominant in Uran mangroves and is represented by 11 families, followed by order Ciconiiformes with 5 families. The species diversity comprises 33 residents, 20 winter visitors and 3 occasional visitors. At present, ecological conditions in mangroves of Uran supports moderate density of birds but due to intense industrialization and urbanization, pollution of Uran coast cannot be ignored. Therefore, data presented in this paper can be taken as a base line data