Ionospheric scintillation studies

The diffracted field of a monochromatic plane wave was characterized by two complex correlation functions. For a Gaussian complex field, these quantities suffice to completely define the statistics of the field. Thus, one can in principle calculate the statistics of any measurable quantity in terms of the model parameters. The best data fits were achieved for intensity statistics derived under the Gaussian statistics hypothesis. The signal structure that achieved the best fit was nearly invariant with scintillation level and irregularity source (ionosphere or solar wind). It was characterized by the fact that more than 80% of the scattered signal power is in phase quadrature with the undeviated or coherent signal component. Thus, the Gaussian-statistics hypothesis is both convenient and accurate for channel modeling work

PENGARUH TIPE TUTUPAN LAHAN TERHADAP IKLIM MIKRO DI KOTA BITUNG

This study aimed to analyze the effect of land cover types to micro-climate of and analyze the effect microclimate to the trees and open land towards amenities environment for human. The City of Bitung has selected as a research site because it planned for mega projects. They are Special Economic Zones (KEK), International Relations Ports and Manado-Bitung Highways. The research used primary and secondary data. The parameters measured for each land cover includes the elements of microclimate namely: Air Temperature, Humidity and Solar Radiation. Data analysis using techniques T test, F test and Analysis of amenities based on the data of air temperature and humidity, it can be calculated by Temperature Humadity Index (THI). The measurement results microclimate taken at four different land cover that is at the city park, Central Business District (CBD), housing and industry. The results of this study prove the hypothesis that there are differences in the average value of the temperature and humidity in the trees, open land. Tree vegetation structures more effectively reduce the air temperature. The structure of the vegetation canopy of trees that have rounded and more densely branched patterns, height being between 6-10 m and serves to overshadow proved more effective in improving amenities in the surrounding area. Based on the value of THI, all land cover both parks, CBD, residential and industrial categorized uncomfortable because the average is at a value> 27. Housing area has very little green space. One of the efforts to improve the quality of the microclimate in order to enhance the user experience is to provide a good environment garden by planting vegetation predominant tree combined with shrubs and grasses to balance and harmonize between buildings and the environment also have aesthetic value. In the industrial area, the high levels of air pollution resulting from the production process so that recommended a good landscape arrangement, by expanding area of town forest and planting vegetation of trees that can absorb large numbers of pollutants result in healthy and fresh air for the region

COMPARATIVE STUDY OF HAEMATOLOGICAL PARAMETERS IN FISHES FROM THE NATURAL HABITAT, MADURAI REGION

The heamatological profile of two freshwater fishes Labeo rohita (Rohu) and Channa striatus (Murrel) with a relationship to the sex and the water quality under natural habitat was analyzed. The freshwater fishes were collected from the pond located in Thodaneri, Vadipatti taluk, Madurai district, Tamil Nadu, India. In heamatology studies, no significant variation was observed in Heamoglobin content and found almost the same in both the fish irrespective of the sex and also falls in the range of control value. In differential Leucocyte count (DLC) the following blood components Lymphocyte, Eosinophil, and Monocyte count were significantly higher than the control values and the values are found maximum in Rohu when compared to Murrel.RBC (Erythrocyte) count was almost the same in both the fish and the value falls between the range of control value Packed Cell Volume (PCV) count was almost the same in both the fish and the value falls between the range of control value. The values of Hb and PCV were found higher in male fish as compared to female fish. The leucocyte count is also higher in the males when compared to the females of both Rohu and Murrel. These may be also influenced by physiological activity, feeding habits, infectious agents, water quality parameters, and the environmental stress on the organism

Tuning hole mobility in InP nanowires

Transport properties of holes in InP nanowires were calculated considering electron-phonon interaction via deformation potentials, the effect of temperature and strain fields. Using molecular dynamics, we simulate nanowire structures, LO-phonon energy renormalization and lifetime. The valence band ground state changes between light- and heavy-hole character, as the strain fields and the nanowire size are changed. Drastic changes in the mobility arise with the onset of resonance between the LO-phonons and the separation between valence subbands.Comment: 4 pages, 4 figure

A Comprehensive Statistical Analysis of the Gas Distribution in Lyman-limit and Damped Lyman-alpha Absorption Systems

In this paper we show how to use data on Lyman-limit and Damped Lyman-alpha absorption systems to derive the hydrogen ionization fractions and the distribution of the face-on total gas column density. We consider axially symmetric, randomly oriented absorbers, ionized by an external background radiation field in order to relate the face-on total gas distribution to that of the neutral hydrogen observed along the line of sight. We devise a statistical procedure based on the Maximum Likelihood criterion, that is able to treat simultaneously data coming from different surveys and statistically recovers the "true" column densities in the presence of large uncertainties: this is especially important for Lyman-limit systems which leave an unmeasurable residual flux at wavelengths shorter than the Lyman break. We make use of simulated data to look for possible observational biases and extensively test our procedure. For a large statistical sample of real data in the redshift range [1.75,3.25] (collected from all published surveys) our Maximum Likelihood procedure gives a power-law slope for the total hydrogen distribution of -2.7. All together Lyman-limit systems therefore contain more gas than Damped Lyman-alpha systems. Analysis of data at other redshifts shows that more observations are needed to reach a compelling evidence for a cosmological evolution of the slope of the gas distribution.Comment: 30 pages with 7 eps figures, LaTeX accepted for publication in ApJ main journa

Sharp HI edges at high z: the gas distribution from Damped Lyman-alpha to Lyman-limit absorption systems

We derive the distribution of neutral and ionized gas in high redshift clouds which are optically thick to hydrogen ionizing radiation, using published data on Lyman-limit and Damped Lyman-alpha absorption systems in the redshift range 1.75 < z < 3.25. We assume that the distribution of the hydrogen total (HI+HII) column density in the absorbers follows a power law K N_H^{-alpha}, whereas the observed HI column density distribution deviates from a pure power law as a result of ionization from a background radiation field. Comparison of the models and observations give Maximum Likelihood solutions for the exponent alpha and for X, the value of log(N_H/N_HI) when the Lyman-limit optical depth is unity: alpha=2.7^{+1.0}_{-0.7} and X=2.75\pm0.35. X is much lower than what would be obtained for a gaseous distribution in equilibrium under its own gravity but the ratio of dark matter to gas density is not well constrained being log(eta_0)=1.1\pm 0.8. An extrapolation of our derived power law distribution towards systems of lower column density, the Lyman-alpha forest, favours models with log(eta_0) < 1.1 and alpha=2.7-3.3. With alpha appreciably larger than 2, Lyman-limit systems contain more gas than Damped Lyman-alpha systems and Lyman-alpha forest clouds even more. Estimates of the cosmological gas and dark matter density due to absorbers of different column density around z=2.5 are also given.Comment: 21 pages, 6 figures. Accepted for publication in Ap

Nanophotonic modal dichroism: mode-multiplexed modulators

As the diffraction limit is approached, device miniaturization to integrate more functionality per area becomes more and more challenging. Here we propose a strategy to increase the functionality-per-area by exploiting the modal properties of a waveguide system. With such an approach the design of a mode-multiplexed nanophotonic modulator relying on the mode-selective absorption of a patterned in-dium-tin-oxide (ITO) is proposed. Full-wave simulations of a device operating at the telecom wavelength of 1550 nm show that two modes can be independently modulated, while maintaining performances in line with conventional single-mode ITO modulators reported in the recent literature. The proposed design principles can pave the way to a class of mode-multiplexed compact photonic devices able to effectively multiply the functionality-per-area in integrated photonic systems. (C) 2016 Optical Society of America1153Ysciescopu