Time for pulse traversal through slabs of dispersive and negative (ϵ\epsilon, μ\mu) materials

The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity ($\epsilon$) and magnetic permeability ($\mu$) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-P\'{e}rot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wigner delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon polariton modes in frequency ranges with negative $\epsilon$ or $\mu$ is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulse propagating across a slab with n=-1. We have checked that the traversal times are positive and subluminal for pulses with sufficiently large bandwidths.Comment: 9 pages, 9 figures, Submitted to Phys. Rev.

Complete controllability of quantum systems

Sufficient conditions for complete controllability of $N$-level quantum systems subject to a single control pulse that addresses multiple allowed transitions concurrently are established. The results are applied in particular to Morse and harmonic-oscillator systems, as well as some systems with degenerate energy levels. Morse and harmonic oscillators serve as models for molecular bonds, and the standard control approach of using a sequence of frequency-selective pulses to address a single transition at a time is either not applicable or only of limited utility for such systems.Comment: 8 pages, expanded and revised versio

Extreme nonlinear electrodynamics in metamaterials with very small linear dielectric permittivity

We consider a sub-wavelength periodic layered medium whose slabs are filled by arbitrary linear metamaterials and standard nonlinear Kerr media and we show that the homogenized medium behaves as a Kerr medium whose parameters can assume values not available in standard materials. Exploiting such a parameter availability, we focus on the situation where the linear relative dielectric permittivity is very small thus allowing the observation of the extreme nonlinear regime where the nonlinear polarization is comparable with or even greater than the linear part of the overall dielectric response. The behavior of the electromagnetic field in the extreme nonlinear regime is very peculiar and characterized by novel features as, for example, the transverse power flow reversing. In order to probe the novel regime, we consider a class of fields (transverse magnetic nonlinear guided waves) admitting full analytical description and we show that these waves are allowed to propagate even in media with $\epsilon0$ since the nonlinear polarization produces a positive overall effective permittivity. The considered nonlinear waves exhibit, in addition to the mentioned features, a number of interesting properties like hyper-focusing induced by the phase difference between the field components.Comment: 12 pages, 7 figure

Morphological structures and drug release effect of multiple electrospun nanofibre membrane systems based on PLA, PCL, and PCL/Magnetic nanoparticle composites

Biopolymers are good carrier materials in relation to efficient release sustainability for encapsulated drugs. In particular, electrospun polymer/composite fibre membranes can offer greater benefits owing to their competitive release features as well as large specific surface areas. In this study, multiple electrospun nanofibre membrane systems were utilised including different material systems such as poly(lactic acid) (PLA), poly(ε-caprolactone) (PCL), and PCL/magnetic nanoparticle (MP) composites loaded with tetracycline hydrochloride (TCH) as a therapeutic compound for their potential use in drug delivery applications. Such electrospun nanofibres were investigated to understand how composite constituents could tailor surface morphology for drug release control and biodegradation effect of PCL electrospun nanofibers on a long term for different drug release systems. Fibre diameter appeared to be decreased considerably with the addition of TCH drug. It was also evident that average fibre diameter was reduced when embedding MPs owing to the enhancement of solution conductivity. The encapsulation of TCH drug was found to be effective, as evidenced by Fourier transform infrared (FTIR) spectra. Thermogravimetric analysis (TGA) data revealed no significant change in the thermal stability of PCL with the inclusion of TCH and MPs. However, the use of TCH to PLA delayed the thermal degradation. Glass transition temperature (TQ) and melting temperature (TM) of PCL were decreased with the inclusion of MPs and TCH. The degree of crystallinity (XC) for PCL diminished when incorporated with MPs. Additional TCH to PLA, PCL, and PCL/MP nanocomposites resulted in a moderate decrease in (XC). TCH might be dispersed in an amorphous state within nanofibre membranes. Over the short-term periods, it was clearly seen that TCH release from PCL nanofibre membranes was higher as opposed to PLC/MP and PLA counterparts. On the contrary, such a drug release from PLC membranes became relatively slow owing to its high (XC). Further, the mass loss results were consistent with those obtained from in vitro drug release. Overall, TCH release kinetics of PCL/TCH nanofibre membranes were better estimated by Zeng model as opposed to PLA/TCH counterparts

Experimental Study of Thermal oxidation Damage in Ceramic Composites Using Ultrasonic Waves

One major concern about ceramic matrix composites (CMC) is their high temperature stability, especially in an oxidizing environment. In general CMC materials are composed of matrix, fiber, and interphase layers (mainly fiber coatings and/or reaction product layers). It is known [1,2] that the properties of CMC materials are dominated by the interphase. However, this interphase often suffers from oxidation reactions caused by diffusion of oxygen through the matrix [1,3]. As a result desirable properties are not retained

Sustainable Management of Rainwater through Integrated Watershed Approach for Improved Rural Livelihoods

Rainwater, an essential resource for growing food also plays an important role in providing livelihood support for rural people in the rain-fed regions. Eighty percent of the world’s agricultural land is rain-fed and contributes to about 60 percent of the global food production. An insight into the rain-fed regions shows a grim picture of water-scarcity, fragile ecosystems and land degradation due to soil erosion by wind and water, low rainwater use efficiency, high population pressure, poverty, low investments in water use efficiency measures, poor infrastructure and inappropriate policies. The current rainwater use efficiency for crop production is low ranging between 30 and 45 %; thus annually about 300-800 mm of seasonal rainfall goes unproductive, lost either as surface run-off or deep drainage. The challenge, therefore, is to improve rural livelihoods through efficient and sustainable rainwater management technologies for increasing rain-fed productivity and thereby contribute to food and livelihood security. Watershed as an entry point acts as a beginning to address the issues of sustainable rainwater management for improving livelihoods. An innovative integrated farmer participatory consortium watershed management model developed by ICRISAT along with NARS partners is a holistic model unlike the earlier watershed approaches which were sectoral with emphasis only on the soil and water conservation measures. The integrated watershed approach uses new science tools, links onstation research to on-farm watersheds, provides technical backstopping through consortium of institutions with convergence of livelihood-based activities. The core theme of the model is sustainable natural resource management for increasing the farm productivity and improving the rural livelihoods. The approach covers issues starting with conservation of natural resources and ensures increased productivity and incomes through convergence of all necessary activities to achieve the good. In order to ensure equity for women and landless people, emphasis is put on development of common property resources as well as establishing micro-enterprises. This integrated watershed approach enables to have ‘winwin’ situations for sustaining productivity and improving livelihoods as it includes convergence of activities at various levels thus enhancing community participation and creating income-generating options. Successful results from on-farm integrated watersheds are discussed. However, the challenge is to scale up the approach to larger areas on sustainable basis. Lessons learnt from past watershed experiences are that we need to focus on issues such as keeping the community interest for participation; institutions to continue activity for maintenance after the project activity ceases; maintaining the link between the watershed and supporting institutions for technical backstopping, appropriate policies for groundwater use and common property resources and innovative ways to merge common wastelands. Thus the lessons learnt from the integrated watershed management can help reengineer suitable roadmaps for maximizing returns to investment on watershed programs. With ever changing policies and economies, improved institutional and policy support mechanisms in partnership with stakeholders especially the farmers, market links for products, value addition products for rural areas, infrastructure and suitable ways to meet the challenges for the target areas need to be addresse

Morpho-Agronomic Diversity in Pole-Type Common Bean (Phaseolus vulgaris L.) Landraces from Lushai Hills of North-East India

The present study was based on morphological and agronomical characterization of 23 pole-type common bean (Phaseolus vulgaris L.) landraces collected from Lushai hills of North-East India. Extensive variation in plant and seed traits was found in 16 morphological and agronomical characters. Cluster analysis based on Euclidean distance grouped the genotypes into five main branches, reflecting their growth type and reproductive traits. Significant positive or negative correlation was observed among important traits. Principal component analysis was used for assessing patterns of variation by accounting for all the 10 quantitative and six qualitative variables together. Ordination among accessions showed that the first five principal components had Eigen values greater than one, and cumulatively accounted for 72% of the variation. Characterization based on quantitative and qualitative traits enabled separation of accessions into various groups representing landraces with distinct characters

Exploiting temporal information for 3D pose estimation

In this work, we address the problem of 3D human pose estimation from a sequence of 2D human poses. Although the recent success of deep networks has led many state-of-the-art methods for 3D pose estimation to train deep networks end-to-end to predict from images directly, the top-performing approaches have shown the effectiveness of dividing the task of 3D pose estimation into two steps: using a state-of-the-art 2D pose estimator to estimate the 2D pose from images and then mapping them into 3D space. They also showed that a low-dimensional representation like 2D locations of a set of joints can be discriminative enough to estimate 3D pose with high accuracy. However, estimation of 3D pose for individual frames leads to temporally incoherent estimates due to independent error in each frame causing jitter. Therefore, in this work we utilize the temporal information across a sequence of 2D joint locations to estimate a sequence of 3D poses. We designed a sequence-to-sequence network composed of layer-normalized LSTM units with shortcut connections connecting the input to the output on the decoder side and imposed temporal smoothness constraint during training. We found that the knowledge of temporal consistency improves the best reported result on Human3.6M dataset by approximately $12.2\%$ and helps our network to recover temporally consistent 3D poses over a sequence of images even when the 2D pose detector fails

Nano-Engineered Environment for Nerve Regeneration: Scaffolds, Functional Molecules and Stem Cells

One of the most complex systems in the human body is the nervous system, which is divided into the central and peripheral nervous systems. The regeneration of the CNS is a complex and challenging biological phenomenon hindered by the low regenerative capacity of neurons and the prohibition factors in response to nerve injuries. To date, no effective approach can achieve complete recovery and fully restore the functions of the nervous system once it has been damaged. Developments in neuroscience have identified properties of the local environment with a critical role in nerve regeneration. Advances in biomaterials and biomedical engineering have explored new approaches of constructing permissive environments for nerve regeneration, thereby enabling optimism with regard to nerve-injury treatment. This article reviews recent progress in nanoengineered environments for aiding nerve-injury repair and regeneration, including nanofibrous scaffolds, functional molecules, and stem cells.postprin

Nano-Engineered Environment for Nerve Regeneration: Scaffolds, Functional Molecules and Stem Cells

One of the most complex systems in the human body is the nervous system, which is divided into the central and peripheral nervous systems. The regeneration of the CNS is a complex and challenging biological phenomenon hindered by the low regenerative capacity of neurons and the prohibition factors in response to nerve injuries. To date, no effective approach can achieve complete recovery and fully restore the functions of the nervous system once it has been damaged. Developments in neuroscience have identified properties of the local environment with a critical role in nerve regeneration. Advances in biomaterials and biomedical engineering have explored new approaches of constructing permissive environments for nerve regeneration, thereby enabling optimism with regard to nerve-injury treatment. This article reviews recent progress in nanoengineered environments for aiding nerve-injury repair and regeneration, including nanofibrous scaffolds, functional molecules, and stem cells.postprin