Growth options and poverty reduction in Ethiopia

"This study assesses which agricultural subsectors have the strongest capacity to drive economic growth and poverty reduction in Ethiopia, and what kind of agricultural and nonagricultural growth is needed to achieve the millennium development goal of halving the 1990 poverty rate by 2015. A spatially disaggregated, economywide model was developed under the study, enabling the analysis of growth and poverty reduction linkages at national and regional levels using national household surveys, agricultural sample surveys, geographic information systems, and other national and regional data. The study reveals that agriculture has the potential to play a central role in decreasing poverty and increasing growth in Ethiopia, primarily through growth in staple crops and livestock. Agricultural growth also requires concurrent investments in roads and other market conditions. At the subnational level, similar rates of agricultural growth have different effects on poverty, necessitating regionally based strategies for growth and poverty reduction." Authors' AbstractPoverty alleviation ,Agricultural growth ,Millenium Development goal ,Spatial analysis (Statistics) ,Disaggregation ,Household surveys ,Ethiopia ,africa ,

Ethiopia: growth options and poverty reduction

Rural poor, Urban poor, Market access, Agricultural growth, Poverty reduction,

Effect of Uniaxial Stress on Gallium, Beryllium, and Copper-doped Germanium Hole Population Inversion Lasers

The effects of stress on germanium lasers doped with single, double, and triple acceptors have been investigated. The results can be explained quantitatively with theoretical calculations and can be attributed to specific changes in the energy levels of acceptors in germanium under stress. In contrast to previous measurements, gallium-doped Ge crystals show a decrease in lasing upon uniaxial stress. The decrease seen here is attributed to the decrease in heavy hole effective mass upon application of uniaxial stress, which results in a decreased population inversion. The discrepancy between this work and previous studies can be explained with the low compensation level of the material used here. Because the amount of ionized impurity scattering in low-compensated germanium lasers is small to begin with, the reduction in scattering with uniaxial stress does not play a significant role in changing the laser operation. Beryllium-doped germanium lasers operate based on a different mechanism of population inversion. In this material it is proposed that holes can transfer between bands by giving their energy to a neutral beryllium atom, raising the hole from the ground to a bound excited state. The free hole will then return to zero energy with some probability of entering the other band. The minimum and maximum E/B ratios for lasing change with uniaxial stress because of the change in effective mass and bound excited state energy. These limits have been calculated for the case of 300 bar [100] stress, and match very well with the observed data. This adds further credence to the proposed mechanism for population inversion in this material. In contrast to Be and Ga-doped lasers, copper-doped lasers under uniaxial stress show an increase in the range of E and B where lasing is seen. To understand this change the theoretical limits for population inversion based on both the optical phonon mechanism and the neutral acceptor mechanism have been calculated. The data are described by population inversion via optical phonons at zero pressure. However, both mechanisms most likely occur when the slightly higher, non-uniform pressures of 300 bar are applied, leading to an increase in population inversion and lasing. Upon further increasing the pressure to 600 bar, the limits for population inversion decrease and a decrease in the lasing is seen

Optimization of a 3.6-THz quantum cascade laser for real-time imaging with a microbolometer focal plane array

The article of record as published may be found at http://dx.doi.org/10.1117/12.767671Real-time imaging in the terahertz (THz) spectral range was achieved using a 3.6-THz quantum cascade laser (QCL) and an uncooled, 160x120 pixel microbolometer camera fitted with a picarin lens. Noise equivalent temperature difference of the camera in the 1-5 THz frequency range was calculated to be at least 3 K, confirming the need for external THz illumination when imaging in this frequency regime. After evaluating the effects of various operating parameters on laser performance, the QCL found to perform optimally at 1.9 A in pulsed mode with a 300 kHz repetition rate and 10-20% duty cycle; average output power was approximately 1 mW. Under this scheme, a series of metallic objects were imaged while wrapped in various obscurants. Single-frame and extended video recordings demonstrate strong contrast between metallic materials and those of plastic, cloth, and paper—supporting the viability of this imaging technology in security screening applications. Thermal effects arising from Joule heating of the laser were found to be the dominant issue affecting output power and image quality; these effects were mitigated by limiting laser pulse widths to 670 ns and operating the system under closed-cycle refrigeration at a temperature of 10 K.This work is supported by the Air Force Office of Scientific Research (AFOSR)

Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera

Optics Letters, Volume 33, No. 5, pp. 440-442 (March 1, 2008)Real-time imaging in the terahertz (THz) spectral range was achieved using a milliwatt-scale, 2.8 THz quantum cascade laser and an uncooled, 160 120 pixel microbolometer camera modified with Picarin optics...This work is supported by the Air Force Office of Scientific Research (AFOSR)

Pond measurements of ice and snow thickness, temperature profile and solar radiation in 2021, close to Lake Elmo

Continuous observations were made of ice thickness, snow thickness, ice, and water temperatures at 1 ft increments of levels in the pond from surface to bottom, ambient temperatures above the ice surface, incoming shortwave and longwave radiation of the test and control sections. The observations were made from January 13, 2021 to March 20th 2021. The pond used for these observations is situated near Lake Elmo, Minnesota, USA. The pond consists of an artificial excavation lined with 0.045 EDPM film over a geofabric base. The shape is essentially conical with a nominal diameter of 100 ft, depth of 6 ft, and a slope of 1 to 4. A simple bisection using plastic sheeting was made to provide for a single control section and a single test section. The data was collected to experimentally determine effects of surface albedo modification on ice melt and thermodynamic processes of a freshwater pond. In this experiment we applied a coating of reflective hollow glass microspheres to a test section, while leaving a control section unmodified. The data was used to compare the rates of ice melt, albedo and pond water and ice temperatures and energy changes of the test and control section to determine the effectiveness of the surface albedo modification using hollow glass microspheres. To collect data, we used nominally identical sets of instruments for the test and control sides of the pond, to measure temperature, incoming and reflected longwave and shortwave radiation, ice thickness. Each suite was made up of a Raspberry Pi 4B+, two strings of DS18B20 temperature sensors, an apogee SN-500 net radiometer as well as an ice thickness gauge made up of an upwards facing blue robotics Ping sonar positioned in the water below the ice and a snow thickness gauge made up of a downwards facing MaxBotix in-air ultrasonic sensor. The radiometers were positioned on suspension cables along the southwest-northeast axis of the pond about 1 m above the ice and about 4,5 m from the center of the pond. The ice thickness gauges were each positioned about 3.3 meters from the pond center, towards the north on the control side and towards the west on the test side. The temperature sensor strings were of different lengths and designed to measure the temperature of the water in the deeper and more shallow areas of the pond. The longer string used for the deeper, more central area was made up of 7 temperature sensors, one in air close to the termination at the Raspberry Pi, and then 6 others coming up from the bottom each spaced about a foot from one another. The deep sensor strings were deployed through holes drilled in the ice about 2.4 m from the center in the southwest and northeast directions. The strings were positioned so that the topmost sensor of the bottom 6 was at the ice-air interface when testing began in January, and the bottom most sensor was weighed down and close to the bottom.. The shorter temperature sensor string was made up of 4 temperature sensors, each spaced about a foot from one another and positioned closer to the edge of the pond where the topmost sensor was at the ice-air interface and the bottom sensor was close to the bottom. These shallower sensor strings were again deployed via holes drilled in the ice, at about 5.5 m from the pond center in the same directions

Laboratory particle size measurements of hollow glass microsphere products 'Potters 25P45' and '3M K1'

We commissioned laboratory evaluations of several available hollow glass microsphere products. Particle Technology Laboratories made particle size measurements for 3M™ K1 and Potters Sphericel™ 25P45 hollow glass microspheres (HGMs). The measurements were made in August 2020 at PTL's laboratory in Downers Grove, IL. The purpose of the measurements was to evaluate widely available hollow glass microsphere materials obtainable from multiple sources for effectiveness in reducing ice melt. A further purpose was to select materials for evaluation in field experiments and to compare size distributions. A further purpose was to determine the percentage of particles below 10 microns for evaluation for safety. A further purpose was to compare particle size measurements with reflectivity measurements. The measurements were made by laser diffraction using a Malvern Mastersizer 3000 (Particle Technology Laboratories, Downers Grove, IL). Particles were delivered with dry sample introduction due to the buoyancy of the particles in typical solvents used for particle size measurement. The lowest venturi setting was used to avoid damage and breakage to the microspheres during sample measurement. Optical microscopy of the samples after particle size measurement confirmed the integrity of the particles through the laser diffraction measurement

Meteorological measurements in 2021, close to Lake Elmo

Continuous observations were made of weather conditions at the pond, including temperature, wind velocity, wind direction, solar radiation, humidity, and rainfall. The observations were made from February 3rd, 2021 to March 21th 2021, The pond used for these observations is situated in Lake Elmo, Minnesota, USA, the pond center located at 45.0220, -92.8916. An Ambient Weather Model WS-2902C observing station was situated on the North-East side of the pond, about 2 m from the nominal shoreline. The data was collected to experimentally determine effects of surface albedo modification on ice melt and thermodynamic processes of a freshwater pond. In this experiment we applied a coating of reflective hollow glass microspheres to a test section, while leaving a control section unmodified. The data was used to develop a thermodynamic model of the pond using weather conditions to model heat flows and to confirm snowfall events. The Ambient Weather observing station transmits its readings via WiFi to a WS-2902C receiver which is connected wirelessly to the Internet, and the readings are stored for one year. These data points were downloaded and processed

Laboratory particle reflectivity measurements of hollow glass microsphere products 'Potters 25P45' and '3M K1'

We commissioned laboratory evaluations of several available hollow glass microsphere products. Covalent Metrology made reflectivity measurements for 3M™ K1 and Potters Sphericel™ 25P45 hollow glass microspheres (HGMs). The measurements were made from August 25 to September 11, 2020 at Covalent Metrology in Sunnyvale, CA. The purpose of the measurements was to evaluate widely available hollow glass microsphere materials obtainable from multiple sources for effectiveness in reducing ice melt. A further purpose was to select materials for evaluation in field experiments and compare laboratory results with results from field experiments. A further purpose was to determine the effect of water on reflectivity. While the particles are known to have high reflectivity in their dry state, it was unknown how much the reflectivity might decrease if particles are embedded in the ice or on the surface of water, since the refractive index of water (n=1.33 at 589 nm) is closer to the refractive index of glass (n ~1.52, depending on glass composition) than the refractive index of air (n=1.00). The reflectivity of the HGM materials was measured with a Perkin-Elmer 1050 UV-Vis-NIR Spectrometer at 5 nm resolution using a 150mm integrating sphere to collect the diffuse reflectance. Samples were placed on the reflectance sample plate inside a Spectrosil® Far UV quartz cuvette of fixed pathlength (Starna Type 20 short path length, demountable). To measure the change in reflectivity with varying layer thicknesses of hollow glass microsphere materials, HGM were loaded into cuvettes with pathlengths varying from 0.2mm to 1 mm in thickness. Measurements of the reflectivity of the cuvette were taken on just the cuvette alone, then measurements were made with the cuvette loaded with material. The reflectivity of the cuvette alone was subtracted from these measurements to provide measurements of the material reflectivity. The silica material was loaded into the cuvette and a doctor blade method was used to remove excess material in the well. The cuvette was sealed and placed onto the integrating sphere port with the cuvette well facing the incident light. The HGM material was loaded into the cuvette and a doctor blade method was used to remove excess material in the well. The cuvette was sealed and placed onto the integrating sphere port with the cuvette well facing the incident light. To measure the reflectivity of HGM in water, a few droplets of water were deposited onto the sample after doctor blading, taking care not to disturb or overly saturate the layer. Due to the hydrophilic nature of these materials, the surfaces appeared to be fully wet. The UV-Vis reflectivity of the K1 and 25P45 hollow glass microspheres was measured as a function of optical path length and of the surrounding medium. While the particles are known to have high reflectivity in their dry state, it was unknown how much the reflectivity might decrease if particles are embedded in the ice or on the surface of water as the ice begins to melt, since the refractive index of water (n=1.33 at 589 nm) is closer to the refractive index of glass (n ~1.52, depending on glass composition) than the refractive index of air (n=1.00)

Field and Laboratory Measurements of an Experiment of Surface Albedo Modification using Hollow Glass Microspheres to Reduce Ice Melt

We conducted a controlled experiment to determine effects of surface albedo modification using hollow glass microspheres on ice melt and thermodynamic processes of a pond. Continuous field observations were made of ice thickness, snow thickness, ice, and water temperatures at 1 ft increments of levels in the pond from surface to bottom, ambient temperatures above the ice surface, incoming shortwave and longwave radiation of the test and control sections. The observations were made from January 13, 2021 to March 20, 2021. The pond used for these observations is situated near Lake Elmo, Minnesota, USA. We also commissioned laboratory evaluations of reflectivity and particle size of available hollow glass microsphere products. The field data was collected to experimentally determine effects of surface albedo modification on ice melt and thermodynamic processes of a freshwater pond. In this experiment we applied a coating of reflective hollow glass microspheres to a test section, while leaving a control section unmodified. The data was used to compare the rates of ice melt, albedo and pond water and ice temperatures and energy changes of the test and control sections to determine the effectiveness of the surface albedo modification using hollow glass microspheres