419 research outputs found
Economic Impacts of Regional Approaches to Rural Development: Initial Evidence on the Delta Regional Authority
This study assesses the initial economic outcomes of the Delta Regional Authority (DRA), which began funding rural development projects in the Mississippi Delta region in 2002. The study focuses on non-metropolitan DRA counties and similar counties elsewhere in the Mississippi Delta region and the southeast, using a quasi-experimental approach that combines matching methods, double and triple difference and switching regression estimation. We find that per capita income and transfer payments grew more rapidly in DRA counties than similar non-DRA counties, and that these impacts are larger in counties in which DRA spending was larger. Each additional dollar of DRA spending per capita is associated with an increase of 8 in earnings (primarily in the health care and social services sector) and $5 in transfer payments. The increase in transfer payments is mainly due to increased medical transfer payments. We also find that the number of hospital beds per capita increased more in counties where DRA spending per capita was greater. These findings suggest that investments supported by the DRA in improved medical facilities are promoting additional health sector earnings and medical transfer payments.rural economic development programs, economic impacts, Mississippi Delta, Delta Regional Authority, matching estimators, double difference, triple difference estimation, switching regression, Community/Rural/Urban Development, Research Methods/ Statistical Methods, R58, R11, O18, C21,
Recreation, Tourism, and Rural Well-Being
The promotion of recreation and tourism has been both praised and criticized as a rural development strategy. This study uses regression analysis to assess the effect of recreation and tourism development on socioeconomic conditions in rural recreation counties. The findings imply that recreation and tourism development contributes to rural well-being, increasing local employment, wage levels, and income, reducing poverty, and improving education and health. But recreation and tourism development is not without drawbacks, including higher housing costs. Local effects also vary significantly, depending on the type of recreation area.recreation, tourism, recreation counties, rural development, economic indicators, social indicators, rural development policy, Community/Rural/Urban Development, Resource /Energy Economics and Policy,
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Mainstream Success Following Placement in a Modified Type II Setting
The topic of alternative schools is widely available in the literature; however, once a student has been labeled a "troublemaker" and has been placed in a District Alternative Education Program (DAEP), a Type II setting, there is limited information about the overall success of students upon their return to the mainstream. This study compared the success of students formerly placed in a modified disciplinary Type II setting, once they have returned to the mainstream, with their success prior to disciplinary placement. The purpose of the study was to examine if disciplinary measures that remove students from the mainstream environment negatively impact the variables that measure school success, despite legislative mandates such as No Child Left Behind, which advocates success for every student. The population for this study was 86 7th- through 11th-grade students assigned to a DAEP in Texas during the spring of 2003. A comparison of pre- and post-placement dependent variables measuring school success-attendance, passing core courses, behavioral achievement, standardized test score achievement, recidivism, and dropout rates-comprised this study. The independent variables-gender, ethnicity, grade level, socioeconomic status, and disciplinary offense-were used to compare and analyze each dependent variable. The dependent variables of attendance, passing core courses, and behavior demonstrated a decline in the measurement of school success across time. The only dependent variable that demonstrated improvement between the pre- and post-placement periods was achievement on standardized test scores. From the number of students who withdrew from the mainstream during the post-placement semesters, large recidivism and dropout rates were determined, which reflected the large percentage of students who were not successful in the district's mainstream. The comparisons of dependent variables by independent variables resulted in significance only in the analyses of attendance by grade level. This interaction was determined to be significant since p < .05. During both post-placement semesters, 11th-grade attendance increased by 20.2 points. Students in the 7th, 8th, and 9th grades maintained a slight increase in attendance between the pre-placement and first post-placement semester yet experienced an attendance decline in the second post-placement semester. This decline was seen in all three grade levels between the pre-placement and the second post-placement semesters. Attendance among tenth graders declined throughout all semesters of the study. The comparison of attendance by disciplinary offense resulted in a large effect size (eta2). The eta2 reported within 29.8% accuracy in variability when attendance was compared by disciplinary offense. Students placed for assault demonstrated a 27.7 point increase in attendance by the second post-placement semester. Despite the comparison of attendance by the grade level of students being the only significant result, and the comparison of attendance by disciplinary offense resulting in a large effect size, several specific conclusions were drawn from the analyses of the pre- and post-placement data measuring school success. All dependent variable measurements, with the exception of standardized test score achievement, resulted in an overall reduction of mean scores across time. This decline indicates that students do demonstrate a decline in school success following a removal from a mainstream setting
Flow Measurements Using Particle Image Velocimetry in the Ultracompact Combustor
The potential for the ultracompact combustor (UCC) lie in future research to reduced fuel consumption and improved engine performance. Velocity measurements performed on the UCC test rig at the Air Force Institute of Technology revealed flow patterns and time-averaged turbulence statistics for data taken burning hydrogen fuel in a straight and a curved cavity vane configuration. Over an equivalence ratio from 0.7 to 1.5, the straight vane configuration showed spanwise velocity decreased linearly with distance from the cavity vane over the width of the main channel. Increasing the flow rates and holding the equivalence ratio and ratio of cavity to main airflow rates constant, flow velocities in the main channel showed an increase with the curved circumferential configuration but a decrease with the straight circumferential configuration. Turbulence intensity is expected to be a major contributing factor, specifically since measured at 15% and 21% in the main channel for the straight and curved configurations, respectively. The results also show how the radial vane cavity (RVC) created strong vorticity throughout the main flow supporting a recirculation zone for mixing. Peak vorticity occurred farthest from the cavity vane suggesting the angle of the radial vane cavity is effective in generating increasing flow rotation
An Experimental Investigation into the Effect of Flap Angles for a Piezo-Driven Wing
This article presents a comparison of results from six degree of freedom force and moment measurements and Particle Image Velocimetry (PIV) data taken on the Air Force Institute of Technology\u27s (AFIT) piezoelectrically actuated, biomimetically designed Hawkmoth, Manduca Sexta, class engineered wing, at varying amplitudes and flapping frequencies, for both trimmed and asymmetric flapping conditions to assess control moment changes. To preserve test specimen integrity, the wing was driven at a voltage amplitude 50% below the maximum necessary to achieve the maximal Hawkmoth total stroke angle. 86 and 65 stroke angles were achieved for the trimmed and asymmetric tests respectively. Flapping tests were performed at system structural resonance, and at 10% off system resonance at a single amplitude, and PZT power consumption was calculated for each test condition. Two-dimensional PIV visualization measurements were taken transverse to the wing planform, recorded at the mid-span, for a single frequency and amplitude setting, for both trimmed and asymmetric flapping to correlate with the 6-DoF balance data. Linear velocity data was extracted from the 2-D PIV imagery at 1/2 and 1 chord locations above and below the wing, and the mean velocities were calculated for four separate wing phases during the flap cycle. The mean forces developed during a flap cycle were approximated using a modification of the Rankine-Froude axial actuator disk model to calculate the transport of momentum flux as a measure of vertical thrust produced during a static hover flight condition. Values of vertical force calculated from the 2-D PIV measurements were within 20% of the 6-DOF force balance experiments. Power calculations confirmed flapping at system resonance required less power than at off resonance frequencies, which is a critical finding necessary for future vehicle design considerations
Instantaneous flow measurements in a supersonic wind tunnel using spectrally resolved Rayleigh scattering
Results of a feasibility study to apply laser Rayleigh scattering to non-intrusively measure flow properties in a small supersonic wind tunnel are presented. The technique uses an injection seeded, frequency doubled Nd:YAG laser tuned to an absorption band of iodine. The molecular Rayleigh scattered light is filtered with an iodine cell to block light at the laser frequency. The Doppler-shifted Rayleigh scattered light that passes through the iodine cell is analyzed with a planar mirror Fabry-Perot interferometer used in a static imaging mode. An intensified CCD camera is used to record the images. The images are analyzed at several subregions, where the flow velocity is determined. Each image is obtained with a single laser pulse, giving instantaneous measurements
Changes in auditory perceptions and cortex resulting from hearing recovery after extended congenital unilateral hearing loss
Monaural hearing induces auditory system reorganization. Imbalanced input also degrades time-intensity cues for sound localization and signal segregation for listening in noise. While there have been studies of bilateral auditory deprivation and later hearing restoration (e.g. cochlear implants), less is known about unilateral auditory deprivation and subsequent hearing improvement. We investigated effects of long-term congenital unilateral hearing loss on localization, speech understanding, and cortical organization following hearing recovery. Hearing in the congenitally affected ear of a 41 year old female improved significantly after stapedotomy and reconstruction. Pre-operative hearing threshold levels showed unilateral, mixed, moderately-severe to profound hearing loss. The contralateral ear had hearing threshold levels within normal limits. Testing was completed prior to, and three and nine months after surgery. Measurements were of sound localization with intensity-roved stimuli and speech recognition in various noise conditions. We also evoked magnetic resonance signals with monaural stimulation to the unaffected ear. Activation magnitudes were determined in core, belt, and parabelt auditory cortex regions via an interrupted single event design. Hearing improvement following 40 years of congenital unilateral hearing loss resulted in substantially improved sound localization and speech recognition in noise. Auditory cortex also reorganized. Contralateral auditory cortex responses were increased after hearing recovery and the extent of activated cortex was bilateral, including a greater portion of the posterior superior temporal plane. Thus, prolonged predominant monaural stimulation did not prevent auditory system changes consequent to restored binaural hearing. Results support future research of unilateral auditory deprivation effects and plasticity, with consideration for length of deprivation, age at hearing correction, degree and type of hearing loss
Flapping Wing Micro Air Vehicle Bench Test Setup
The purpose of this research was to develop testing methods that can be used to determine the forces, moments, and deflections involved in flapping wing aerodynamics. To pursue the research, a flapping wing mechanism and wings with spans ranging from 9.1 inches to 12.1 inches were built. A variety of mechanisms, capable of, alternatively, purely flapping, flapping with pitch, and flapping with pitch and out-of-plane motion were conceptualized and drawn using solid modeling software. Two of the simpler designs, a single degree-of-freedom flapping mechanism and the two-degree of freedom flapping mechanism were fabricated using a rapid prototype 3-D printer, and sustained operation was demonstrated. A thrust stand and a six-component force balance were used to gather force data from the flapping-only mechanism, combined with a variety of wing shapes. Four high-speed cameras were used to capture the motion of the wings. To minimize intrusiveness an array of laser dots was projected onto the wing during flapping and photogrammetry software was used to analyze the images and determine a shape profile of the wing composed of a frame and membrane during flapping. While the focus of this research was on the bench test setup development, some insight into the influence of wing design on the forces acting on the mechanism was gained
Flow Measurements Using Particle Image Velocimetry in the Ultracompact Combustor
The potential for the ultracompact combustor (UCC) lie in future research to reduced fuel consumption and improved engine performance. Velocity measurements performed on the UCC test rig at the Air Force Institute of Technology revealed flow patterns and time-averaged turbulence statistics for data taken burning hydrogen fuel in a straight and a curved cavity vane configuration. Over an equivalence ratio from 0.7 to 1.5, the straight vane configuration showed spanwise velocity decreased linearly with distance from the cavity vane over the width of the main channel. Increasing the flow rates and holding the equivalence ratio and ratio of cavity to main airflow rates constant, flow velocities in the main channel showed an increase with the curved circumferential configuration but a decrease with the straight
circumferential configuration. Turbulence intensity is expected to be a major contributing factor, specifically since measured at 15% and 21% in the main channel for the straight and curved configurations, respectively. The results also show how the radial vane cavity (RVC) created strong vorticity throughout the main flow supporting a recirculation zone for mixing. Peak vorticity occurred farthest from the cavity vane suggesting the angle of the radial vane cavity is effective in generating increasing flow rotation
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