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A Himalayan cloudburst event, which occurred on 3 August 2012 in the Uttarkashi (30.73° N, 78.45° E) region of Uttarakhand, India, was analyzed. The near-surface atmospheric variables were analyzed to study the formation, evolution, and triggering mechanisms of this cloudburst. In order to improve upon the understanding provided by the observations, numerical simulations were performed using the Weather Research and Forecasting (WRF) model, configured with a single domain at 18 km resolution. The model was tuned using variation of different parameterizations (convective, microphysical, boundary layer, radiation, and land surface), and different model options (number of vertical levels, and spin-up time), which resulted in a combination of parameters and options that best reproduced the observed diurnal characteristics of the near-surface atmospheric variables. Our study demonstrates the ability of WRF in forecasting precipitation, and resolving synoptic-scale and mesoscale interactions. In order to better understand the cloudburst, we configured WRF with multiply nested two-way-interacting domains (18, 6, 2 km) centered on the location of interest, and simulated the event with the best configuration derived earlier. The results indicate that two mesoscale convective systems originating from Madhya Pradesh and Tibet interacted over Uttarkashi and, under orographic uplifting and in the presence of favorable moisture condition, resulted in this cloudburst event. [ABSTRACT FROM AUTHOR]

In this paper the electrode geometry effects on the impedance spectroScopy of biological cell culture have been studied under low intensity sinusoidal electric field with a view to design improved electrode structures for continuous cell growth monitoring. To achieve this, impedance estimation has been done by modified distributed analysis both in presence and absence of confluent cell layer by taking into account the effect of solution resistance and the separation between the electrodes. The model has been applied on fibroblast cell culture (3T3) in the frequency range of 10 Hz to 10 kHz. It has been observed that for most of the frequencies, the resistance sensitivity (Sr) is less than the capacitance sensitivity (Sc) and does not increase monotonically with radius of working electrode (Re) unlike Sc. Further, the nature of variation of Sr and Sc are fairly contradictory with variation in Re and separation between the electrodes (d-Re). Thus an optimum geometry has been selected based on a figure of merit (FOM) which has been defined as the product of Sr and Sc. The maximum FOM corresponds to Re=90 ?m and d=3Re for a typical frequency of 4 kHz. Observations at 4 kHz show that the optimized geometry yields values of Sr that are almost 5 times higher than those from the conventional geometry (Re=125 μm and d=300Re). This increase permits the small signals resulting from the micromotion of cells to be more easily seen. [ABSTRACT FROM PUBLISHER]

Abstract: A novel text line extraction technique is presented for multi-skewed document images of handwritten English or Bengali text. It assumes that hypothetical water flows, from both left and right sides of the image frame, face obstruction from characters of text lines. The stripes of areas left unwetted on the image frame are finally labelled for extraction of text lines. The success rate of the technique, as observed experimentally, are 90.34% and 91.44% for handwritten Bengali and English document images, respectively. The work may contribute significantly for the development of applications related to optical character recognition of Bengali/English text. [Copyright &y& Elsevier]

Single charge transfer reactions in the collision of ions at a laboratory energy of 2 keV with N 2 were observed using translational energy spectroscopy (TES). Within the limitation of the energy analyser resolution (∼ 8/ q eV, q being the ionic charge number), the translational energy spectrum shows a single broad charge transfer peak with a rich substructure. The latter looks like a conglomeration of closely spaced channels clumped together, corresponding mainly to charge transfer into excited states , rather than into the ground state. The reaction channel assignments were made using data available in the literature. Our findings are in accord with a recent experimental result, but there are no theoretical calculations to compare our experimental measurements with. [ABSTRACT FROM AUTHOR]

Starting with H[SUP+][CH[SUB3]C(O)CH[SUB2]C(O)CH[SUB3]] (denoted H[SUP+]PD), the protonated diketone-water clusters H[SUP+]PD(H[SUB2]O)[SUBn] (n = 1-3) have been characterized by density functional theory calculations in combination with vibrational predissociation spectroscopy to explore the conformational changes of a protonated bifunctional ion solvated by water in the gas phase. Theoretical calculations for H[SUP+]PD revealed that the ion contains an intramolecular hydrogen bond (IHB), with two oxygen atoms bridged by the extra proton in an O-H[SUP+] ... O form. Attachment of one water molecule to it readily ruptures this IHB, replacing the H[SUP+] by the H[SUB3]O[SUP+] moiety. Further replacement of the IHB by two water molecules occurs at n = 2 and the -C(O)CH[SUB2]C(O)- chain is fully opened (or unfolded) after transfer of the extra proton to the water trimer at n = 3. To verify the computational findings, infrared spectroscopic measurements were performed using a vibrational predissociation ion trap spectrometer to identify cluster isomers from the signatures of hydrogen bonded and non-hydrogen bonded OH stretching spectra of H[SUP+]PD(H[SUB2]O)[SUB2,3] produced in a corona discharge supersonic expansion. Besides open form isomers, evidence for the formation of water-bridged structures has been found for H[SUP+]PD(H[SUB2]O)[SUB3] at an estimated temperature of 200 K. A detailed illustration of the unfolding steps as well as the energy profiles for the evolution of a two-water bridge isomer from the protonated H[SUP+]PD monomer are analysed pictorially including both stable intermediates and transition states in the present investigation. [ABSTRACT FROM AUTHOR]

Size-selected hydroxide ion water tetramers and pentamers [OH[sup -] (H[sub 2]O)[sub 4,5]], produced by a supersonic expansion, have been investigated using vibrational predissociation spectroscopy in conjunction with ab initio calculations based on density functional theory (DFT). The observed spectra in the frequency range 2650-3850cm [sup -1] show some broad absorption bands attributed to the free and hydrogen bonded OH stretches of OH[sup -] (H[sub 2]O)[sub 4,5] at an estimated cluster temperature of 170 K. DFT calculations performed at the B3LYP/6-31+ G* level reveal five and eight possible low lying isomeric forms for OH[sup -] (H[sub 2]O)[sub 4] and OH (H[sub 2]O)[sub 5], respectively. The global minimum isomer of the tetramer is tri-solvated cyclic, which is energetically more stable than the tetra-solvated wheel-shaped form with an OH ion at its centre. Compact cage-like lowest energy structures are found for the pentamer, in which the water molecules can act either as a single-donor-single-acceptor, as a double-proton-donor, or as a double-donor-single-acceptor in both the first and the second solvation shell of the OH ion core. Interconversion among the isomers appears to be rapid as manifested in the observed spectra dominated by broad and congested absorptions. To understand the nature of spectral broadening and congestion, systemic comparisons of the results are made against those of the corresponding protonated cations, H[sup +](H[sub 2]O)[sub n+1] and the corresponding halide anions, X[sup -] (H[sub 2]O)[sub n], X = F, Cl, Br, and I. It is suggested that the spectral complexities observed for OH[sup -](H[sub 2]O)[sub 4,5] are predominantly a result of sampling configurations with a large distribution of O[sub solvent]-O[sub ion]-O[sub solvent] angles and O[sub solvent] · · · H-O[sub solvent] distances between water molecules in the first and/or second hydration shells, together with the existence of more than one isomer in the supersonic expanson and rapid isomeric interconversion among them. [ABSTRACT FROM AUTHOR]

Cluster isomers of H[sup +](CH[sub 3]OH)[sub 4]H[sub 2]O have been identified by vibrational predissociation spectroscopy in combination with mass-selected detection of photofragments. Ab initio calculations indicate that the cluster ion can exist in either CH[sub 3]OH[sub 2][sup +](CH[sub 3]OH)[sub 3]H[sub 2]O or H[sub 3]O[sup +](CH[sub 3]OH)[sub 4] isomeric forms. They can dissociate via a methanol loss or water loss channel, depending on the structure of the isomers. While water loss is the dominant channel of the dissociation, the methanol loss channel is readily accessible by the H[sub 3]O[sup +]-centered cluster isomer. We demonstrate in this study that mass-selected detection of photofragments produced by vibrational excitation is an effective way of identifying cluster isomers in the gas phase. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Electrospray ionization (ESI) has been employed to produce Li+(CH3OH)m for infrared spectroscopic studies using a vibrational predissociation spectrometer. A gradual blue shift of the CO stretching frequency from 1023 cm−1 to 1027 cm−1 was observed as m increases from 5 to 10, supporting the suggestion for the formation of the second solvation-shell in Li+(CH3OH)5, in accord with the prediction by density functional theory calculations performed at the B3LYP/6-311+G**//6-31+G* level. We demonstrate in this work that the ESI source is applicable not only to the infrared study of Li+(CH3OH)m but also to other alkali metal methanol cluster ions as well. [Copyright &y& Elsevier]

Developing point-of-care (PoC) diagnostic platforms for carcinoembryonic antigen detection is essential. However, thefew implementations of transferring the signal amplification strategies in electrochemical sensing on paper-based platforms are not satisfactory in terms of detection limit (LOD). In the quest for pushing down LOD, majority of the research has been targeted towards development of improved nanostructured substrates for entrapping more analyte molecules and augmenting the electron transfer rate to the working electrode. But, such approaches have reached saturation. This paper focuses on enhancing the mass transport of the analyte towards the sensor surface through the application of an electric field, in graphene-ZnO nanorods heterostructure. These hybrid nanostructures have been deposited on flexible polyethylene terephthalate substrates with screen printed electrodes for PoC application. The ZnO nanorods have been functionalized with aptamers and the working sensor has been integrated with smartphone interfaced indigenously developed low cost potentiostat. The performance of the system, requiring only 50 µl analyte has been evaluated using electrochemical impedance spectroscopy and validated against commercially available ELISA kit. Limit of detection of 1 fg/ml in human serum with 6.5% coefficient of variation has been demonstrated, which is more than three orders of magnitude lower than the existing attempts on PoC device. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate a unique FET system composed of vertically aligned MoS 2 nanosheets for real time, label free monitoring of zeta potential and dimension of mesenchymal stem cells during proliferation. To avoid the interference from non-specifically adsorbed macromolecules, a time varying electric field with an optimized frequency of 10 kHz has been applied at the gate and effective gate bias has been estimated from the real time drain current measurement in an electrical double layer gated cell-coupled FET platform. Special signal patterns corresponding to the alterations in the cell membrane potential have been observed. Extraction of cell parameters from the experimental observations, using closed set of equations reveal that the results correlate well with the gold standards and a high transconductance has enabled tracking of cell count with sufficient accuracy. The MoS 2 FET signal has been compared with the pH change of the cell culture medium and the signal follows the cell proliferation related activity more closely than the pH change. Thus, it may be expected that this platform can substitute the existing time consuming and laborious methods. • A unique FET system composed of vertically aligned MoS 2 nanorods. • Real time, label free monitoring of zeta potential and dimension of stem cells. • A time varying electric field has been applied at the gate. • Effective gate bias has been estimated from the drain current. [ABSTRACT FROM AUTHOR]

Investigation of coherent absorption resonance via electromagnetically induced absorption (EIA) spectra in rubidium vapour has been done in presence of a repumping laser and an external magnetic field. The EIA line shape gets enhanced and symmetric with the application of the repumping laser. In presence of an external magnetic field the amplitude of the EIA resonance gradually diminishes and at higher magnetic field, two absorption dip-like structures along with a transmission peak in between is obtained. Theoretically calculated spectra based on density matrix approach show a good agreement with the observations. [ABSTRACT FROM AUTHOR]