Cloud cover, cloud liquid water and cloud attenuation at Ka and V bands over equatorial climate

Cloud cover statistics and their diurnal variation have been obtained from in situ and satellite measurements for three equatorial locations. Cloud liquid water content, 0 °C isotherm height and cloud attenuation have also been obtained from radiosonde measurement using the so-called Salonen model at Kuala Lumpur (Malaysia). The results show a strong seasonal variation of cloud cover and cloud liquid water content on the two monsoon seasons. The Liquid Water Content (LWC) obtained from radiosonde and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is higher during the Northeast Monsoon season, which corresponds to the period of higher percentage cloud cover and high rainfall accumulation. The International Telecommunication Union—Region (ITU-R) model underestimates the cumulative distribution of LWC values at the present station. The relationship of the cloud attenuation, derived from the profiles of liquid water density and temperature within the cloud, shows an underestimate by the data obtained from the ITU-R model. The cloud attenuation at Kuala Lumpur is somewhat underestimated by the ITU-R model up to about 1.2 dB at Ka (30 GHz) and 3.4 dB at V (50 GHz) bands. The results of the specific attenuation can be used for the estimation of cloud attenuation at microwave and millimetre wave over earth-space paths. The present data are important for planning and design of satellite communications at Ka and V bands on the Earth–space path in the equatorial region

Geometry induced entanglement transitions in nanostructures

We model quantum dot nanostructures using a one-dimensional system of two interacting electrons. We show that strong and rapid variations may be induced in the spatial entanglement by varying the nanostructure geometry. We investigate the position-space information entropy as an indicator of the entanglement in this system. We also consider the expectation value of the Coulomb interaction and the ratio of this expectation to the expectation of the confining potential and their link to the entanglement. We look at the first derivative of the entanglement and the position-space information entropy to infer information about a possible quantum phase transition.Comment: 3 pages, 2 figures, to appear in Journal of Applied Physic

Challenges and Opportunities to Improve Tuberculosis Screening Among Immigrant Plantation Workers in Sabah, Malaysia

Tuberculosis (TB) among immigrants has substantial contribution to the TB epidemiology in Sabah. This study aimed to determine the yield of screening for TB disease among immigrant plantation workers in Sabah, Malaysia. This was a prospective cohort study involving 482 legal immigrant workers aged 18 years and above, consented and available at study sites during the study period. Workers with previous history of TB or currently on TB treatment were excluded from participation. Symptom based questionnaire was administered along with both chest radiograph and sputum samples collection for symptomatics participants. Out of 482 plantation workers creened, there was no case of active TB detected among the 44 (9.1%) symptomatics participants. Finding of low TB yield in this study was rather unexpected but this indicates the real challenges for the local health authority to come out with more cost effective screening programs, including reducing stigma, in active TB screening among migrant population

Effect of confinement potential geometry on entanglement in quantum dot-based nanostructures

We calculate the spatial entanglement between two electrons trapped in a nanostructure for a broad class of confinement potentials, including single and double quantum dots, and core-shell quantum dot structures. By using a parametrized confinement potential, we are able to switch from one structure to the others with continuity and to analyze how the entanglement is influenced by the changes in the confinement geometry. We calculate the many-body wave function by `exact' diagonalization of the time independent Schr\"odinger equation. We discuss the relationship between the entanglement and specific cuts of the wave function, and show that the wave function at a single highly symmetric point could be a good indicator for the entanglement content of the system. We analyze the counterintuitive relationship between spatial entanglement and Coulomb interaction, which connects maxima (minima) of the first to minima (maxima) of the latter. We introduce a potential quantum phase transition which relates quantum states characterized by different spatial topology. Finally we show that by varying shape, range and strength of the confinement potential, it is possible to induce strong and rapid variations of the entanglement between the two electrons. This property may be used to tailor nanostructures according to the level of entanglement required by a specific application.Comment: 10 pages, 8 figures and 1 tabl

Cloud attenuation studies of the six major climatic zones of Africa for Ka and V satellite system design

Cloud cover statistics, cloud base and top height, cloud temperature, frequency of precipitation, freezing height, total cloud liquid water content (TCLWC) and cloud attenuation data have been obtained for the six major climatic zones of Africa. The present results reveal a strong positive correlation between the monthly distribution of low cloud cover, cloud top height, cloud temperature, and frequency of precipitation in the six zones. The cumulative distribution of the TCLWC derived from radiosonde measurement in each climatic zone shows a departure from the TCLWC recommended by the ITU Study Group 3 data, with an exceedance percentage difference of 32% to 90% occurring 0.01% to 10% of the time. The underestimation of the TCLWC is greatest in the tropical rain forest. A comparison of the cloud attenuation cumulative distribution in the Ka and V bands reveals that the International Telecommunication Union – Region (ITU-R) is an intergovernmental organization that develops rain model based on collected data around the world. This model underestimates the cloud attenuation in all of the six climatic zones by 2.0 dB and 4.7 dB for the arid Sahara desert, 1.3 dB and 3.0 dB in semi-arid North Africa, 1.3 dB and 1.5 dB in savannah North Africa, 2.0 dB and 3.6 dB in the tropical rain forest, 1.3 dB and 2.9 dB in savannah South Africa and 0.9 dB and 2.6 dB in semi-arid South Africa, respectively, at 30 and 50 GHz. Overall, the cloud attenuation in the tropical rain-forest zone is very high because of the high annual total cloud cover(98%), high annual frequency of precipitation (4.5), low annual clear sky amount (8%), high cloud depth (10,937 m), high 0°C isotherm height (4.7 km), high TCLWC (4.0 kg/m2 at 0.01%) and low seasonal cloud base height (356 m)

Clinical Approach to Chronic Pancreratitis

Chronic pancreatitis is still considered an uncertain process with an undetermined pathogenesis and ill defined treatment. Chronic pancreatitis is distinguished from acute pancreatitis based on structural and functional differences. In acute pancreatitis, the gland is normal prior to the attack, and returns to normal after an acute attack, while in chronic pancreatitis, the gland is already in an abnormal state prior to or following an attack or prior to and following an acute attack. The most common local complication of chronic pancreatitis is the formation of pseudocysts. Psedocysts are usually formed due to passage obstruction of the pancreatic tract (retention cyst) or due to recurrent acute exacerbation Several pancreatic abnormalities, such as stones, ductal stricture, fluid collection, and functional sphincter abnormality, could be treated using endoscopy. Adjuvant treatment for biliary duct abnormality such as biliary stricture due to pancreatitis, and stent insertion in cases of duodenal obstruction, could also be performed via endoscop

Atmospheric gas impact on fixed satellite communication link a study of its effects at Ku, Ka and V bands in Nigeria

The total atmospheric absorption due to Oxygen and water vapour on the earth-space path at Ku (12/14 GHz), Ka (20/30 GHz), and V (40/50 GHz) bands was evaluated for communication with Nigeria communication satellite (Nigcomsat1) on both uplink and down link at 0.01 % unavailability of an average year. The basic input climatic data used include monthly and yearly mean meteorological parameters of surface and vertical profiles of pressure, temperature, and relative humidity obtained from recent measurement from space by the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft for the period 2002 to 2006. The International Telecommunication Union Radio Propagation Recommendation (ITU-RP 676, 2009) procedure was used for the computation of gaseous attenuation for each of the 37-stations in Nigeria. Attenuation values were obtain for both uplink and downlink frequencies, at Ku, Ka and V bands, total atmospheric absorption was determined to be between (0.11 to 0.24) dB, (0.7 to 1.1) dB and (0.82 to 3.1) dB for Ku, Ka, and V bands respectively. Contour maps showing a consistent signal absorption due to Oxygen is generally higher in the South-West region and water-vapour attenuation higher in the South-South part of Nigeria are presented