The Relationship Between Servant Leadership and Student Achievement in Southwest Virginia Schools

The purpose of this correlational study is to test the theory of servant leadership that relates the servant leadership characteristics of school principals to student achievement in Southwest Virginia schools. The primary independent variable was principals\u27 servant leadership characteristics as derived from a self-assessment survey (SASL). The dependent variable was student achievement as measured by students\u27 scores on the Virginia Department of Education Standard of Learning achievement tests in math and reading. Other variables tested were principal total experience in education, principal total experience in administration and principal education level. The data analysis chosen for this research is the Pearson Product-Moment Correlation Coefficient, which is more commonly known as either Pearson\u27s correlation or Pearson\u27s r. However, because 3 out of 6 variables failed normality tests, Spearman\u27s rho, a nonparametric test, was chosen as the best analysis for the monotonic data. The results of analysis yielded a significant positive correlation of principal servant leadership characteristics and reading achievement scores. There were no other significant findings among other variables tested

Onshore Transport of Elopomorph Leptocephali and Glass Eels (Pisces: Osteichthyes) in the Florida Keys

The influx of elopomorph leptocephali and glass eels to Florida Bay was monitored on 160 nights from January through December 1993. Metamorphic leptocephali and glass eels were both captured in channel nets moored in Channel Five near Long Key, FL. Eighty-eight percent of the 2,811 leptocephali collected were speckled worm eels (Myrophis punctatus, n = 2,486). The remaining 12% of leptocephali consisted of nine species, including key worm eels (Ahlia egmontis, n = 153), shrimp eels (Ophichthus gomesi, n = 69), and moray eels (Gymnothorax spp., n = 33). The glass eels collected were Myrophis punctatus (n = 230) and Ahlia egmontis (n = 34). Recruitment of leptocephali and glass eels into Florida Bay was seasonal. Myrophis punctatus leptocephali recruited into Florida Bay during fall and winter and were most abundant during November-January. Peak periods of recruitment were associated with nighttime moonless flood tides, strong onshore winds, and easterly (along-shelf) winds. Ahlia egmontis leptocephali recruited during January-April. Ophichthus gomesi was the only species with major recruitment during the summer and fall (July-November). All of the glass eels were captured from January to April

Understanding wind turbine power converter reliability under realistic wind conditions

The reliability of wind turbine power converters is crucial for analyzing wind energy project costs, and for estimating maintenance and downtime. The published literature in this field relies on evaluating the reliability effect of wind speed to estimate the converter lifetime. However, this paper demonstrates that wind turbulence intensity, which has not been widely considered in similar reliability analyses, shows a significant impact on converter lifetime. This paper uses 821 10‐min wind speed time series sampled at 1 Hz on the two most commonly deployed wind turbine converter topologies: the two‐level voltage source and the three‐level neutral point clamped. Electromechanical and thermal modelling, combined with statistical analysis shows that mean wind speed and turbulence intensity both impact the lifetime of both converter topologies. However, the paper estimates that the three‐level converter can operate 2.4 to 4.0 times longer than the two‐level converter depending on the operating wind speed and turbulence intensity

Carbon fluxes in ecosystems of Yellowstone National Park predicted from remote sensing data and simulation modeling

<p>Abstract</p> <p>Background</p> <p>A simulation model based on remote sensing data for spatial vegetation properties has been used to estimate ecosystem carbon fluxes across Yellowstone National Park (YNP). The CASA (Carnegie Ames Stanford Approach) model was applied at a regional scale to estimate seasonal and annual carbon fluxes as net primary production (NPP) and soil respiration components. Predicted net ecosystem production (NEP) flux of CO₂is estimated from the model for carbon sinks and sources over multi-year periods that varied in climate and (wildfire) disturbance histories. Monthly Enhanced Vegetation Index (EVI) image coverages from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) instrument (from 2000 to 2006) were direct inputs to the model. New map products have been added to CASA from airborne remote sensing of coarse woody debris (CWD) in areas burned by wildfires over the past two decades.</p> <p>Results</p> <p>Model results indicated that relatively cooler and wetter summer growing seasons were the most favorable for annual plant production and net ecosystem carbon gains in representative landscapes of YNP. When summed across vegetation class areas, the predominance of evergreen forest and shrubland (sagebrush) cover was evident, with these two classes together accounting for 88% of the total annual NPP flux of 2.5 Tg C yr^-1(1 Tg = 10¹²g) for the entire Yellowstone study area from 2000-2006. Most vegetation classes were estimated as net ecosystem sinks of atmospheric CO₂on annual basis, making the entire study area a moderate net sink of about +0.13 Tg C yr^-1. This average sink value for forested lands nonetheless masks the contribution of areas burned during the 1988 wildfires, which were estimated as net sources of CO₂to the atmosphere, totaling to a NEP flux of -0.04 Tg C yr^-1for the entire burned area. Several areas burned in the 1988 wildfires were estimated to be among the lowest in overall yearly NPP, namely the Hellroaring Fire, Mink Fire, and Falls Fire areas.</p> <p>Conclusions</p> <p>Rates of recovery for burned forest areas to pre-1988 biomass levels were estimated from a unique combination of remote sensing and CASA model predictions. Ecosystem production and carbon fluxes in the Greater Yellowstone Ecosystem (GYE) result from complex interactions between climate, forest age structure, and disturbance-recovery patterns of the landscape.</p

Wind Tunnel Wake Generator

A wake generator for placement in a wind tunnel between a wind source and a test object includes a first frame member having a first track formed thereon, where the first track has a shape including a first side that is substantially rounded and a second side that is substantially flat. The wake generator may include a mounting plate disposed within a perimeter of the first track, where the mounting plate is rotatable relative to the first frame member about a first axis. The wake generator may also include a plurality of bars slidably engaged to the mounting plate and structurally configured to traverse along the first track when the mounting plate is rotated about the first axis, where each of the plurality of bars includes a pivotal connection allowing each of the plurality of bars to pivot about the pivotal connection when traversing along the first track

"You have to be a jack of all trades”:fathers parenting their adolescent with chronic pain

Adolescent chronic pain has an extensive impact on parents, with research typically focused on exploring maternal experiences. This exploratory study sought to identify the specific experiences of six UK fathers who parent an adolescent with chronic pain. Data from semi structured interviews were analysed using interpretative phenomenological analysis. Paternal experiences were characterised by four themes: ‘helplessness’, ‘containment’, ‘balance’ and ‘re-evaluation’. Findings highlighted paternal efforts to manage the impact of adolescent chronic pain by focusing inwardly on the family and adopting multiple roles. Fathers identified ways in which they could renegotiate their relationship with their adolescent to manage pain related disruption

Iliac fixation inhibits migration of both suprarenal and infrarenal aortic endografts

ObjectiveTo evaluate the role of iliac fixation in preventing migration of suprarenal and infrarenal aortic endografts.MethodsQuantitative image analysis was performed in 92 patients with infrarenal aortic aneurysms (76 men and 16 women) treated with suprarenal (n = 36) or infrarenal (n = 56) aortic endografts from 2000 to 2004. The longitudinal centerline distance from the superior mesenteric artery to the top of the stent graft was measured on preoperative, postimplantation, and 1-year three-dimensional computed tomographic scans, with movement more than 5 mm considered to be significant. Aortic diameters were measured perpendicular to the centerline axis. Proximal and distal fixation lengths were defined as the lengths of stent-graft apposition to the aortic neck and the common iliac arteries, respectively.ResultsThere were no significant differences in age, comorbidities, or preoperative aneurysm size (suprarenal, 6.0 cm; infrarenal, 5.7 cm) between the suprarenal and infrarenal groups. However, the suprarenal group had less favorable aortic necks with a shorter length (13 vs 25 mm; P < .0001), a larger diameter (27 vs 24 mm; P < .0001), and greater angulation (19° vs 11°; P = .007) compared with the infrarenal group. The proximal aortic fixation length was greater in the suprarenal than in the infrarenal group (22 vs 16 mm; P < .0001), with the top of the device closer to the superior mesenteric artery (8 vs 21 mm; P < .0001) as a result of the 15-mm uncovered suprarenal stent. There was no difference in iliac fixation length between the suprarenal and infrarenal groups (26 vs 25 mm; P = .8). Longitudinal centerline stent graft movement at 1 year was similar in the suprarenal and infrarenal groups (4.3 ± 4.4 mm vs 4.8 ± 4.3 mm; P = .6). Patients with longitudinal centerline movement of more than 5 mm at 1 year or clinical evidence of migration at any time during the follow-up period comprised the respective migrator groups. Suprarenal migrators had a shorter iliac fixation length (17 vs 29 mm; P = .006) and a similar aortic fixation length (23 vs 22 mm; P > .999) compared with suprarenal nonmigrators. Infrarenal migrators had a shorter iliac fixation length (18 vs 30 mm; P < .0001) and a similar aortic fixation length (14 vs 17 mm; P = .1) compared with infrarenal nonmigrators. Nonmigrators had closer device proximity to the hypogastric arteries in both the suprarenal (7 vs 17 mm; P = .009) and infrarenal (8 vs 24 mm; P < .0001) groups. No migration occurred in either group in patients with good iliac fixation. Multivariate logistic regression analysis revealed that iliac fixation, as evidenced by iliac fixation length (P = .004) and the device to hypogastric artery distance (P = .002), was a significant independent predictor of migration, whereas suprarenal or infrarenal treatment was not a significant predictor of migration. During a clinical follow-up period of 45 ± 22 months (range, 12-70 months), there have been no aneurysm ruptures, abdominal aortic aneurysm–related deaths, or surgical conversions in either group.ConclusionsDistal iliac fixation is important in preventing migration of both suprarenal and infrarenal aortic endografts that have longitudinal columnar support. Secure iliac fixation minimizes the risk of migration despite suboptimal proximal aortic neck anatomy. Extension of both iliac limbs to cover the entire common iliac artery to the iliac bifurcation seems to prevent endograft migration