2,650 research outputs found
Unconventional Assisted Recovery (UAR) historical case study analysis and quantitative feasibility assessment
During the Gulf War, 34 Coalition pilots were shot down, yet only 6 were recovered by conventional CSAR. Consequently, SOF planners began to consider the impact of integrated air defenses upon personnel recovery and to consider a more proactive method of recovery. While serving as a member of the SOCCENT Unconventional Warfare Working Group and as the lead planner for the first UAR training program and exercise for 3rd Special Forces Group, I observed that there was little consideration of similar historical operations and that operators were skeptical of UAR. The purpose of this thesis is to assist the special operations community with the development of doctrine for UAR and to offer SOF commanders a feasibility assessment tool. This purpose was achieved by: (1) Developing a historical perspective of similar missions through case study analysis to determine, via controlled comparison, the key independent variables that determine the success of ground-based SOF recovery operations, and by (2) Conducting quantitative modeling of UAR to determine, through a range of numerically based conditions, a range of feasibility and doctrinal implications for UAR.http://archive.org/details/unconventionalas109455857US Army (USA) autho
Enhanced bipolar fatigue resistance in CaZrO3-modified (K,Na) NbO3 lead-free piezoceramics
The bipolar fatigue behavior of (K,Na) NbO3 (KNN)-based lead-free piezoceramics was investigated. A comparative analysis demonstrated that CaZrO3-modified KNN ceramics exhibited highly enhanced bipolar fatigue resistance due to the reduced lattice distortion (c/a ratio) and coexistence of orthorhombic and tetragonal phases. The hypothesis was verified by systematical studies of cycle-dependent large and small signal parameters and micro-morphologies. It was identified that mechanical stress induced microstructure damage beneath the electrodes renders the KNN ceramics to be vulnerable to bipolar cycling; while the mild fatigue behavior for CaZrO3-modified ones mainly originates from a thermally reversible domain wall pinning.open8
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Bipolar piezoelectric fatigue of Bi(Zn0.5Ti0.5)O3-(Bi0.5K0.5)TiO3-(Bi0.5Na0.5)TiO3 Pb-free ceramics
The piezoelectric fatigue behavior of Pb-free ceramics based on solid solutions of Bi(Zn₀.₅Ti₀.₅)O₃-(Bi₀.5K₀.₅)TiO₃-(Bi₀.₅Na₀.₅)TiO₃ was characterized at 50 kV/cm after 10⁶ bipolar cycles. Ferroelectric compositions containing 2.5% Bi(Zn₀.₅Ti₀.₅)O₃ exhibited only minor losses in maximum strain (~10%). In compositions with 5% Bi(Zn₀.₅Ti₀.₅)O₃ that exhibit large electric field-induced strains, the electromechanical strain actually increased 4%, exhibiting essentially fatigue free behavior. This finding demonstrates that these materials have excellent potential for demanding high cycle applications such as microelectromechanical systems actuators. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4738770]KEYWORDS: Melville, NY 11747-4501 USA, Zirconate titanate ceramics, 2 Huntington quadrangle, Ste 1 N 0 1, Circulation & fulfillment di
A proteinase 3 contribution to juvenile idiopathic arthritis-associated cartilage damage
A full understanding of the molecular mechanisms implicated in the etiopathogenesis of juvenile idiopathic arthritis (JIA) is lacking. A critical role for leukocyte proteolytic activity (e.g., elastase and cathepsin G) has been proposed. While leukocyte elastase’s (HLE) role has been documented, the potential contribution of proteinase 3 (PR3), a serine protease present in abundance in neutrophils, has not been evaluated. In this study we investigated: (1) PR3 concentrations in the synovial fluid of JIA patients using ELISA and (2) the cartilage degradation potential of PR3 by measuring the hydrolysis of fluorescently labeled collagen II in vitro. In parallel, concentrations and collagen II hydrolysis by HLE were assessed. Additionally, the levels of the co-secreted primary granule protein myeloperoxidase (MPO) were assessed in synovial fluid of patients diagnosed with JIA. We report the following levels of analytes in JIA synovial fluid: PR3—114 ± 100 ng/mL (mean ± SD), HLE—1272 ± 1219 ng/mL, and MPO—1129 ± 1659 ng/mL, with a very strong correlation between the PR3 and HLE concentrations (rs = 0.898, p \u3c 1 × 10–6 ). Importantly, PR3 hydrolyzed fluorescently labeled collagen II as efficiently as HLE. Taken together, these novel findings suggest that PR3 (in addition to HLE) contributes to JIA-associated joint damage
Reversing resistance to tembotrione in an Amaranthus tuberculatus (var. rudis) population from Nebraska, USA with cytochrome P450 inhibitors
Background: A population of Amaranthus tuberculatus (var. rudis) was confirmed resistant to 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor herbicides (mesotrione, tembotrione, and topramezone) in a seed corn/soybean rotation in Nebraska. Further investigation confirmed a non-target-site resistance mechanism in this population. The main objective of this study was to explore the role of cytochrome P450 inhibitors in restoring the efficacy of HPPD-inhibitor herbicides on the HPPD-inhibitor resistant A. tuberculatus population from Nebraska, USA (HPPD-R).
Background: A population of Amaranthus tuberculatus (var. rudis) was confirmed resistant to 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor herbicides (mesotrione, tembotrione, and topramezone) in a seed corn/soybean rotation in Nebraska. Further investigation confirmed a non-target-site resistance mechanism in this population. The main objective of this study was to explore the role of cytochrome P450 inhibitors in restoring the efficacy of HPPD-inhibitor herbicides on the HPPD-inhibitor resistant A. tuberculatus population from Nebraska, USA (HPPD-R).
Results: Enhanced metabolism via cytochrome P450 enzymes is the mechanism of resistance in HPPD-R. Amitrole partially restored the activity of mesotrione, whereas malathion, amitrole, and piperonyl butoxide restored the activity of tembotrione and topramezone in HPPD-R. Although corn was injured through malathion followed by mesotrione application a week after treatment, the injury was transient, and the crop recovered.
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Presynaptic BDNF Required for a Presynaptic but Not Postsynaptic Component of LTP at Hippocampal CA1-CA3 Synapses
AbstractBrain-derived neurotrophic factor (BDNF) has been implicated in several forms of long-term potentiation (LTP) at different hippocampal synapses. Using two-photon imaging of FM 1-43, a fluorescent marker of synaptic vesicle cycling, we find that BDNF is selectively required for those forms of LTP at Schaffer collateral synapses that recruit a presynaptic component of expression. BDNF-dependent forms of LTP also require activation of L-type voltage-gated calcium channels. One form of LTP with presynaptic expression, theta burst LTP, is thought to be of particular behavioral importance. Using restricted genetic deletion to selectively disrupt BDNF production in either the entire forebrain (CA3 and CA1) or in only the postsynaptic CA1 neuron, we localize the source of BDNF required for LTP to presynaptic neurons. These results suggest that long-term synaptic plasticity has distinct presynaptic and postsynaptic modules. Release of BDNF from CA3 neurons is required to recruit the presynaptic, but not postsynaptic, module of plasticity
Pyrotechnic Actuator for Retracting Tubes Between MSL Subsystems
An apparatus, denoted the "retractuator" (a contraction of "retracting actuator"), was designed to help ensure clean separation between the cruise stage and the entry-vehicle subsystem of the Mars Science Laboratory (MSL) mission. The retractuator or an equivalent mechanism is needed because of tubes that (1) transport a heat-transfer fluid between the stages during flight and (2) are cut immediately prior to separation of the stages retractuator. The role of the retractuator is to retract the tubes, after they are cut and before separation of the subsystem, so that cut ends of the tubes do not damage thermal-protection coats on the entry vehicle and do not contribute to uncertainty of drag and consequent uncertainty in separation velocity
How Comprehensive and Efficient Are Patient-Reported Outcomes for Rotator Cuff Tears?
BACKGROUND: Increasing emphasis is placed on patient-reported outcomes (PROs) after common orthopaedic procedures as a measure of quality. When considering PRO utilization in patients with rotator cuff tears, several different PROs exist with varying levels of accuracy and utilization.
HYPOTHESIS/PURPOSE: Understanding which disease-specific PRO may be most efficiently administered in patients after rotator cuff repair may assist in promoting increased patient and physician adoption of these useful scores. Using a novel assessment criterion, this study assessed all commonly used rotator cuff PROs. We hypothesize that surveys with fewer numbers of questions may remain comparable (with regard to comprehensiveness) to longer surveys.
STUDY DESIGN: Systematic review.
METHODS: Commonly utilized rotator cuff PROs were analyzed with regard to number of survey components, comprehensiveness, and efficiency. Comprehensiveness (maximum score, 11) was scored as the total number of pain (at rest/baseline, night/sleep, activities of daily living [ADLs], sport, and work) and functional (strength, motion/stiffness, and ability to perform ADLs, sport, and work) metrics included, along with inclusion of quality of life/satisfaction metrics. Efficiency was calculated as comprehensiveness divided by the number of survey components.
RESULTS: Sixteen different PROs were studied. Number of components ranged from 5 (University of California at Los Angeles score [UCLA]) to 36 (Short Form-36 [SF-36], Japanese Orthopaedic Association score [JOA]). The Quality of Life Outcome Measure for Rotator Cuff Disease (RC-QoL) included all 5 pain components, while 7 PROs contained all 5 functional components. Ten PROs included a quality of life/satisfaction component. The most comprehensive scores were the RC-QoL (score, 11) and Penn (score, 10), and the least comprehensive score was the Marx (score, 3). The most efficient PROs were the UCLA, the Quick Disabilities of the Arm, Shoulder, and Hand score (QuickDASH), and Constant scores. The least efficient scores were the JOA and SF-36 scores.
CONCLUSION: Many commonly utilized PROs for rotator cuff tears are lacking in comprehensiveness and efficiency. Continued critical assessment of PRO quality may help practitioners identify the most comprehensive and efficient PRO to incorporate into daily clinical practice
Epidemiological Characteristics of School Playground Injuries
Reports of children’s play-related injuries have remained stagnant according to epidemiology studies of the past 3 decades. This article provides a unique look into the context of playground injuries within an entire school district, demonstrating the prevalence of these injuries. This study reports that playgrounds are the leading location of school injury, comprising one-third of all elementary school injuries. This study found that while head/neck injuries were the most commonly injured body region within the playground environment, the proportion of head/neck injuries decreased with age, whereas the proportion of extremity injuries increased with age. At least 1 upper extremity injury required outside medical attention for every 4 that were treated on-site, making upper extremity injuries roughly twice as likely to require outside medical attention as injuries to other body regions. The data in this study are useful for interpreting injury patterns in the context and evaluation of existing safety standards for playgrounds
Medical students\u27 knowledge of HPV, HPV vaccine, and HPV-associated head and neck cancer
On the basis of their training, medical students are considered the best case scenario among university students in knowledge of the human papillomavirus (HPV). We evaluated differences in knowledge of HPV, HPV vaccine, and head and neck cancer (HNC) among medical students. A previously validated questionnaire was completed by 247 medical students at a Midwestern university. Outcomes of interest were knowledge score for HPV and HPV vaccine, and HNC, derived from combining questionnaire items to form HPV knowledge and HNC scores, and analyzed using multivariate linear regression. Mean scores for HPV knowledge were 19.4 out of 26, and 7.2 out of 12 for HNC knowledge. In the final multivariate linear regression model, sex, race, and year of study were independently associated with HPV and HPV vaccine knowledge. Males had significantly lower HPV vaccine knowledge than females (β = -1.53; 95% CI: -2.53, -0.52), as did nonwhite students (β = -1.05; 95% CI: -2.07, -0.03). There was a gradient in HPV vaccine knowledge based on the year of study, highest among fourth year students (β = 6.75; 95% CI: 5.17, 8.33). Results were similar for factors associated with HNC knowledge, except for sex. HNC knowledge similarly increased based on year of study, highest for fourth year students (β = 2.50; 95% CI: 1.72, 3.29). Among medical students, gaps remain in knowledge of HPV, HPV vaccine, and HPV-linked HNC. Male medical students have significantly lower knowledge of HPV. This highlights the need to increase medical student knowledge of HPV and HPV-linked HNC
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