Viscoelastic shear banding in foam

Shear banding is an important feature of flow in complex fluids. Essentially, shear bands refer to the coexistence of flowing and non-flowing regions in driven material. Understanding the possible sources of shear banding has important implications for a wide range of flow applications. In this regard, quasi-two dimensional flow offers a unique opportunity to study competing factors that result in shear bands. One proposal is the competition between intrinsic dissipation and an external source of dissipation. In this paper, we report on the experimental observation of the transition between different classes of shear-bands that have been predicted to exist in cylindrical geometry as the result of this competition [R. J. Clancy, E. Janiaud, D. Weaire, and S. Hutzlet, Eur. J. Phys. E, {\bf 21}, 123 (2006)]

Impact of boundaries on velocity profiles in bubble rafts

Under conditions of sufficiently slow flow, foams, colloids, granular matter, and various pastes have been observed to exhibit shear localization, i.e. regions of flow coexisting with regions of solid-like behavior. The details of such shear localization can vary depending on the system being studied. A number of the systems of interest are confined so as to be quasi-two dimensional, and an important issue in these systems is the role of the confining boundaries. For foams, three basic systems have been studied with very different boundary conditions: Hele-Shaw cells (bubbles confined between two solid plates); bubble rafts (a single layer of bubbles freely floating on a surface of water); and confined bubble rafts (bubbles confined between the surface of water below and a glass plate on top). Often, it is assumed that the impact of the boundaries is not significant in the ``quasi-static limit'', i.e. when externally imposed rates of strain are sufficiently smaller than internal kinematic relaxation times. In this paper, we directly test this assumption for rates of strain ranging from $10^{-3}$ to $10^{-2} {\rm s^{-1}}$. This corresponds to the quoted quasi-static limit in a number of previous experiments. It is found that the top plate dramatically alters both the velocity profile and the distribution of nonlinear rearrangements, even at these slow rates of strain.Comment: New figures added, revised version accepted for publication in Phys. Rev.

Waves in the solar photosphere

The solar photosphere is a partially ionized medium with collisions between electrons, various metallic ions and neutral hydrogen playing an important role in the momentum and energy transport in the medium. Furthermore, the number of neutral hydrogen atom could be as large as $10^{4}$ times the number of plasma particles in the lower photosphere. The non-ideal MHD effects, namely Ohm, Ambipolar and Hall diffusion can play an important role in the photosphere. We demonstrate that Hall is an important non-ideal MHD effect in the solar photosphere and show that Hall effect can significantly affect the excitation and propagation of the waves in the medium. We also demonstrate that the non-ideal Hall dominated inhomogeneous medium can become parametrically unstable, and it could have important ramification for the photosphere and chromosphere of the sun. The analysis hints at the possibility of solar photosphere becoming parametrically unstable against the linear fluctuations.Comment: 5 Figures and 1 table, accepted for publication in MNRA

Role of Information and communication technology (ICT) in agriculture and extension

Information and communication technology (ICT) aids provide up-to-date information on the market prices of commodities, inputs and consumer trends which ultimately can improve a farmer's negotiating position and their livelihood. Major aspect of ICT is that accurate information should reach the farmers at the right time to make more sustainable use of on-farm resources. Now the question arises that how this information can be disseminated to such a diverse group of the farming community. ICT is going to play greater role in agricultural extension as well as private sector agribusiness, market information and market intelligence. Here this paper review the role of ICT not only in providing greater awareness and knowledge in agriculture technology and information but also in terms of farmer’s attitudes towards trying to adopt new technologies

Discrete nuclear domains of poly(A) RNA and their relationship to the functional organization of the nucleus

The functional organization of the nucleus was studied using a fluorescence microscopy approach which allowed integration of positional information for RNA, DNA, and proteins. In cells from sea urchin to human, nuclear poly(A) RNA was found concentrated primarily within several discrete transcript domains which often surrounded nucleoli. Concentrations of poly(A) RNA were coincident with snRNP antigen clusters, providing evidence for the localization of pre-mRNA splicing at these sites. The spatial relationship of transcript domains with respect to various classes of DNA was established, in that the poly(A) RNA-rich regions coincided with discrete regions of low DNA density and were non-randomly distributed with respect to specific DNA sequences. Centromeric DNA and late-replicating DNA did not overlap transcript domains, whereas a subset of early-replicating DNA may. Results indicate that transcript domains do not result directly from a simple clustering of chromatin corresponding to metaphase chromosomes bands. Finally, observations on the reassembly of these domains after mitosis suggest that the clustering of snRNP antigens may be dependent on the reappearance of pol II transcription. Implications of these findings for overall nuclear structure and function are considered, including a discussion of whether transcript domains may be sites of polymerase II transcription reflecting a clustering of active genes

Optical properties of Yb3+ doped ZnO/MgO nanocomposites

[EN] Yb3þ doped ZnO/MgO nanocomposite were prepared by combustion synthesis method. The samples were further heated to 1000 °C to improve their crystallinity and photoluminescent efficiency. The concentrations of Yb3þ and Mg2þ were varied between 1–2% and 5–70% respectively in prepared samples. The nano-powders were characterized by Scanning Electron Microscopy and X-ray Diffraction for morphology and structural determination. XRD studies have revealed the wurtzite structure for MgxZn1"xO for Mg concentrations below 30%. Higher concentrations of Mg results in Yb3þ doped ZnO/ MgO nanocomposite containing three phases; the wurzite hexagonal phase typical of ZnO, the cubic phase of MgO and a small amount of cubic Yb2O3 phase. As expected, the amount of cubic phase in nanopowders increased with the increase of Mg concentration in ZnO. The crystallite size of ZnO/MgO composites decreased from 55 nm to 30 nm with increase of Mg content. SEM images of Yb3þ doped ZnO/MgO nanocomposite with higher Mg content (450%) showed clearly distinct hexagonal and cubical shaped nano-particles. Photoluminescent emission showed a broad band in the range (435 nm to 700 nm). Pure ZnO nano-phosphor showed an emission peak around 545 nm, which is blue shifted with Mg content. The photoluminescence intensity increased with increase of Mg content in ZnO and it became maximum with 30% Mg concentration. Time resolved decay curves of photoluminescence indicated decay time in microsecond time scaleThis work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R), Generalitat Valenciana (PROMETEUS-II/2014/044) and the European Commission through NanoCIS project (FP7-PEOPLE-2010-IRSES ref. 269279).Marí, B.; Singh, KC.; Verma, N.; Jindal, J. (2016). Optical properties of Yb3+ doped ZnO/MgO nanocomposites. Ceramics International. 42(11):13018-13023. https://doi.org/10.1016/j.ceramint.2016.05.079S1301813023421

Proximal femoral nail- outcome and complications: a prospective study of 125 cases of proximal femoral fractures

Background: Fractures of the proximal femur are relatively common injuries in adults and common source of morbidity and mortality among the elderly. Fractures of the proximal femur include trochantric and subtrochantric fractures. The present study was designed to evaluate and analyze the role of proximal femoral nail (PFN) in the treatment of proximal femoral fractures.Methods: It was a prospective study on 125 cases of proximal femoral fractures. The fractures were classified according to AO classification. Salvati and Wilson Score were used for functional assessment.Results: In this study at 6 months follow up, union was achieved in 123 cases, open reduction was performed in 11% of cases (14 cases). Technical and mechanical complications were noted in 21% cases (27 cases). Reoperation rate was 4% (Five cases). According to Salvati and Wilson scoring system excellent results were seen in 36% of cases (45 cases), good results in 46% cases (58 cases), fair result in 13% cases (16 cases) and poor results in 5% cases (6 cases). Conclusions: It is concluded from our study that proximal femoral nailing is an attractive and suitable implant for Proximal Femoral Fractures and its use in unstable intertrochantric fractures is very encouraging

Astrophysical significance of the anisotropic kinetic alpha effect

The generation of large scale flows by the anisotropic kinetic alpha (AKA) effect is investigated in simulations with a suitable time-dependent space- and time-periodic anisotropic forcing lacking parity invariance. The forcing pattern moves relative to the fluid, which leads to a breaking of the Galilean invariance as required for the AKA effect to exist. The AKA effect is found to produce a clear large scale flow pattern when the Reynolds number, R, is small as only a few modes are excited in linear theory. In this case the non-vanishing components of the AKA tensor are dynamically independent of the Reynolds number. For larger values of R, many more modes are excited and the components of the AKA tensor are found to decrease rapidly with increasing value of R. However, once there is a magnetic field (imposed and of sufficient strength, or dynamo-generated and saturated) the field begins to suppress the AKA effect, regardless of the value of R. It is argued that the AKA effect is unlikely to be astrophysically significant unless the magnetic field is weak and R is small.Comment: 8 pages, 10 figures, submitted to A&

Dissipation of angular momentum in light heavy ion collision

The inclusive energy distributions of fragments (4$\leq$Z$\leq$7) emitted in the reactions $^{16}$O (116 MeV) + $^{27}$Al, $^{28}$Si, $^{20}$Ne (145 MeV) + $^{27}$Al, $^{59}$Co have been measured in the angular range $\theta_{lab}$= 10$^\circ$ - 65$^\circ$. Fusion-fission and deep inelastic components of the fragment emission have been extracted from the experimental data. The angular mometum dissipations in fully damped deep inelastic collisions have been estimated assming exit channel configuration similar to those for fusion-fission process. It has been found that, the angular momentum dissipations are more than those predicted by the empirical sticking limit in all cases. The deviation is found to increase with increasing charge transfer (lighter fragments). Qualitatively, this may be due to stronger friction in the exit channel. Moreover, for the heavier system $^{20}$Ne + $^{59}$Co, the overall magnitude of deviation is less as compared to those for the lighter systems, {\it i.e.}, $^{16}$O + $^{27}$Al, $^{28}$Si, $^{20}$Ne + $^{27}$Al. This may be due to lesser overlap in time scales of fusion and deep inelastic time scales for heavier systems.Comment: 15 pages, 9 figures, accepted for publication in Phys. Rev.