Microwave attenuation and phase rotation by ellipsoidal dust particles

Abstract: Electromagnetic wave propagation suffers attenuation and phase rotation by suspended dust particles where occurrence of sand and dust storms (SDS) is predominant especially in arid and semi-arid regions. The SDS phenomenon has received considerable interest in recent times with emphasis on signal attenuation and phase rotation effects. To this end, mathematical models of dust induced complex scattering are developed and proposed using Rayleigh method to compute attenuation and phase rotation of electromagnetic waves by considering dust particle shapes and best fit ellipsoids. This work also presents a new expression for the relation between visibility and dust concentration. The expression was included in the proposed models whose simulated results, when compared with some published results, show close agreement. Attenuation and phase rotation in dry dust are found to be significant only when visibility becomes severe or at increased microwave bands

Prediction of dust particle-induced cross polarization at microwave and millimeter wave bands

Abstract: The use of dual orthogonal polarizations to optimally conserve frequency spectrum in microwave link, otherwise known as cross polarization, has received considerable interest in the recent time in the field of electromagnetic wave propagation in sand and dust storms. Cross polarization in dust storms occurs due to the non-sphericity of the falling dust particles and the tendency of the particles to align in a direction at a time i.e. canting angle. The realization of a dual-polarized system is however limited by degree of cross polarization discrimination (XPD) that can be achieved between the two orthogonal channels. Therefore, theoretical investigation has been carried out in this work to estimate the cross polarization at microwave and millimeter wave bands by non-spherical dust particles in dust storms. The XPD being the parameter for characterization of cross polarization, is predicted using propagation constants’ differentials and canting angles, as inputs. Apart from both differential phase rotation and attenuation, it has been found that the cross polarization produced by ellipsoidal dust particles strongly depend on the particle canting. XPD decreases with an increase in canting angle. It has also been observed that the values of differential attenuation increase with increasing frequency for visibility and thus depends directly on frequency. Lastly, the obtained results show that cross polarization is significant during severe visibility and for dry dust storm; the XPD is good and acceptable for dual polarization systems

Mobile sink wireless underground sensor communication monitor

Mine disasters claim thousands of human lives and cause millions of property loss every year. The safety of the mine worker is of paramount importance in any underground environment. Advances in the development of Wireless Sensor Networks (WSNs) for monitoring infrastructure health, and environmental conditions provide end users with the benefit of low-cost installation, maintenance and scalability. This paper will investigate the challenges around a development of a real-time mine monitoring system using wireless sensor nodes to prevent mine disasters such as gas explosions or mine collapses. We propose a mobile, real-time gateway that will be able to process data collected from static wireless sensor nodes monitoring underground infrastructure, to prevent underground disasters

Indications for an Extra Neutral Gauge Boson in Electroweak Precision Data

A new analysis of the hadronic peak cross section at LEP 1 implies a small amount of missing invisible width in Z decays, while the effective weak charge in atomic parity violation has been determined recently to 0.6% accuracy, indicating a significantly negative S parameter. As a consequence of these two deviations, the data are described well if the presence of an additional Z' boson, such as predicted in Grand Unified Theories, is assumed. Moreover, the data are now rich enough to study an arbitrary extra Z' boson and to determine its couplings in a model independent way. An excellent best fit to the data is obtained in this case, suggesting the possibility of a family non-universal Z' with properties similar to ones predicted in a class of superstring theories.Comment: 5 pages of ReVTeX, 2 figure

Black carbon physical and optical properties across northern India during pre-monsoon and monsoon seasons

Black carbon (BC) is known to have major impacts on both climate and human health and is therefore of global importance, particularly in regions close to large populations that have strong sources. The size-resolved mixing state of BC-containing particles was characterised using a single-particle soot photometer (SP2). The study focusses on the Indo-Gangetic Plain (IGP) during the pre-monsoon and monsoon seasons. Data presented are from the UK Facility for Airborne Atmospheric Measurements BAe-146 research aircraft that performed flights during the pre-monsoon (11 and 12 June) and monsoon (30 June to 11 July) seasons of 2016. Over the IGP, BC mass concentrations were greater (1.95 µg m−3) compared to north-west India (1.50 µg m−3) and north-east India (0.70 µg m−3) during the pre-monsoon season. Across northern India, two distinct BC modes were recorded; a mode of small BC particles (core diameter <0.16 µm and coating thickness <50 nm) and a mode of moderately coated BC (core diameter <0.22 µm and coating thickness of 50–200 nm). The IGP and north-east India locations exhibited moderately coated black carbon particles with enhanced coating thicknesses, core sizes, mass absorption cross sections, and scattering enhancement values compared to much lower values present in the north-west. The coating thickness and mass absorption cross section increased with altitude (13 %) compared to those in the boundary layer. As the monsoon arrived across the region, mass concentration of BC decreased over the central IGP and north-east locations (38 % and 28 % respectively), whereas for the north-west location BC properties remained relatively consistent. Post-monsoon onset, the coating thickness, core size, mass absorption cross section, and scattering enhancement values were all greatest over the central IGP much like the pre-monsoon season but were considerably reduced over both north-east and north-west India. Increases in mass absorption cross section through the atmospheric column were still present during the monsoon for the north-west and central IGP locations, but less so over the north-east due to lack of long-range transport aerosol aloft. Across the Indo-Gangetic Plain and north-east India during the pre-monsoon and monsoon seasons, solid-fuel (wood burning) emissions form the greatest proportion of BC with moderately coated particles. However, as the monsoon develops in the north-east there was a switch to small uncoated BC particles indicative of traffic emissions, but the solid-fuel emissions remained in the IGP into the monsoon. For both seasons in the north-west, traffic emissions form the greatest proportion of BC particles. Our findings will prove important for greater understanding of the BC physical and optical properties, with important consequences for the atmospheric radiative forcing of BC-containing particles. The findings will also help constrain the regional aerosol models for a variety of applications such as space-based remote sensing, chemistry transport modelling, air quality, and BC source and emission inventories

Syzygium Cumini Leaf Extract Showed Vibriocidal Activity on Selected Diarrhea Causing Bacteria

The objective of the study was to investigate the effect of ethanolic leaf extract (ELE) of Syzygium cumini against Vibrio cholerae particularly two serogroups Ogawa and Inaba. The phenolic content of the ELE was found high which is comparable to ascorbic acid. Brine shrimp lethality bioassay was then performed to check the cytotoxic effects of ELE. The lower LC50 value of ELE obtained indicated its less cytotoxic properties. The antimicrobial activity of the extract was then evaluated by the disc diffusion method against multi-drug resistant Vibrio serogroups Ogawa and Inaba. The extract effectively inhibited the growth of both serogroups. Altogether, the results demonstrated that the ELE of S. cumini has a significant vibriocidal activity that might be useful as a drug for the treatment of cholera

Recent Developments in Precision Electroweak Physics

Developments in precision electroweak physics in the two years since the symposium are briefly summarized.Comment: Update on recent developments, prepared for the publication of the Proceedings of Alberto Sirlin Symposium, New York University, October 2000. 10 pages, 1 figur

Zee Model Confronts SNO Data

We reexamine the solution of the minimal Zee model by comparing with the data of the SNO experiment, and conclude that the model is strongly disfavored but not yet excluded by the observations. Two extensions of the Zee model are briefly discussed both of which introduce additional freedom and can accommodate the data.Comment: 16 pages LaTeX including 7 figure

An Elusive Z' Coupled to Beauty

By extending the standard gauge group to SU(3)_c \times SU(2)_L \times U(1)_Y \times U(1)_X with X charges carried only by the third family we accommodate the LEP measurement of R_b and predict a potentially measurable discrepancy in A_{FB}^{b} in e^+e^- scattering and that D^0\bar{D}^0 mixing may be near its experimental limit. The Z', which explicitly violates the GIM mechanism, can nevertheless be naturally consistent with FCNC constraints. Direct detection of the Z' is possible but challenging.Comment: 12 pages, plus 1 Postscript figure, uses revtex, Discussion of FCNC extende

The Bottom Mass Prediction in Supersymmetric Grand Unification; Uncertainties and Constraints

Grand unified theories often predict unification of Yukawa couplings (e.g., $h_{b} = h_{\tau}$), and thus certain relations among fermion masses. The latter can distinguish these from models that predict only coupling constant unification. The implications of Yukawa couplings of the heavy-family in the supersymmetric extension of the standard model (when embedded in a GUT) are discussed. In particular, uncertainties associated with $m_{t}$ and $m_{b}$, threshold corrections at the low-scale, and threshold and nonrenormalizable-operator corrections associated with a grand-unified sector at the high-scale are parametrized and estimated. The implication of these and of the correlation between $m_{t}$ and the prediction for $\alpha_{s}$ are discussed. Constraints on the $\tan\beta$ range in such models and an upper bound on the $t$-quark pole mass are given and are shown to be affected by the $\alpha_{s}-m_{t}$ correlation. Constraints on the low-scale thresholds are found to be weakened by uncertainties associated with the high-scale.Comment: 23 pages + 7 figures (figures are available upon request), LaTex + RevTex 3.0, UPR-0556