1,456 research outputs found
Ku band deployed assembly and gimbal
Requirements for shuttle orbiter missions to locate satellites for servicing and to communicate when out of touch with a direct ground link were established. A Ku Band deployed antenna system providing an integrated radar and communications function was designed to meet these requirements. The unique features of the gimbal assembly are described with emphasis on the following: edge mounted antenna to minimize stowage volume in shuttle and maximize gain; unique two axis housing and shaft arrangement to accommodate two runs of waveguide and 55 electrical conductors without requiring slip rings; maximum use of aluminum in gimbal structure to reduce costs; and lubricant chosen to survive Earth and space environments
Simulator study of stall/post-stall characteristics of a fighter airplane with relaxed longitudinal static stability
A real-time piloted simulation was conducted to evaluate the high-angle-of-attack characteristics of a fighter configuration based on wind-tunnel testing of the F-16, with particular emphasis on the effects of various levels of relaxed longitudinal static stability. The aerodynamic data used in the simulation was conducted on the Langley differential maneuvering simulator, and the evaluation involved representative low-speed combat maneuvering. Results of the investigation show that the airplane with the basic control system was resistant to the classical yaw departure; however, it was susceptible to pitch departures induced by inertia coupling during rapid, large-amplitude rolls at low airspeed. The airplane also exhibited a deep-stall trim which could be flown into and from which it was difficult to recover. Control-system modifications were developed which greatly decreased the airplane susceptibility to the inertia-coupling departure and which provided a reliable means for recovering from the deep stall
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The future of the subsurface chlorophyll-a maximum in the Canada Basin-A model intercomparison
Six Earth system models and three ocean-ice-ecosystem models are analyzed to evaluate magnitude and depth of the subsurface Chl-a maximum (SCM) in the Canada Basin and ratio of surface to subsurface Chl-a in a future climate scenario. Differences in simulated Chl-a are caused by large intermodel differences in available nitrate in the Arctic Ocean and to some extent by ecosystem complexity. Most models reproduce the observed SCM and nitracline deepening and indicate a continued deepening in the future until the models reach a new state with seasonal ice-free waters. Models not representing a SCM show either too much nitrate and hence no surface limitation or too little nitrate with limited surface growth only. The models suggest that suppression of the nitracline and deepening of the SCM are caused by enhanced stratification, likely driven by enhanced Ekman convergence and freshwater contributions with primarily large-scale atmospheric driving mechanisms. The simulated ratio of near-surface Chl-a to depth-integrated Chl-a is slightly decreasing in most areas of the Arctic Ocean due to enhanced contributions of subsurface Chl-a. Exceptions are some shelf areas and regions where the continued ice thinning leaves winter ice too thin to provide a barrier to momentum fluxes, allowing winter mixing to break up the strong stratification. Results confirm that algorithms determining vertically integrated Chl-a from surface Chl-a need to be tuned to Arctic conditions, but likely require little or no adjustments in the future
Three Keys to Success for Principals (and Their Teachers)
This is the author's accepted manuscript, post peer-review. The publisher's official version is available at: http://dx.doi.org/10.1080/00228958.2008.10516527.What is successful leadership and how can leadership concepts be applied to schools? Hundreds of books and articles and a plethora of executive seminars describe what leadership is and propose strategies for what effective leaders do. Most of these writings and presentations, however, focus on business, with much less information available about how to lead schools. In addition, there is a diversity of opinions about what makes leaders effective. This article suggests that it is possible to extract, reframe, and apply the best of what is known about leadership to help principals be more successful. Moreover, if principals are successful, teachers also are positioned to be successful, with the ultimate impact being successful student learning
Clinical subtype, treatment response, and survival in De Novo and recurrent metastatic breast cancer
Purpose: This study evaluated whether patients with de novo metastatic breast cancer (MBC) have superior outcomes compared to those with recurrent MBC in a contemporary treatment era and examined factors related to outcome differentials. Methods: Using an institutional database, we examined patient and tumor characteristics, treatment response, and outcome among 232 patients with de novo and 612 patients with recurrent MBC diagnosed between 2011 and 2017. Results: De novo MBC had 9-month (m) longer overall survival (OS) than recurrent MBC (36.4 vs 27.4 m, p < 0.001). Contributions to this difference included nearly twofold more HER2-positive (29.3% vs 15.2%) and significantly fewer triple-negative breast cancers (20.3% vs 32.4%, both p < 0.001) in de novo compared with recurrent MBC cohorts. Stratified by clinical subtype, progression-free survival (PFS) on first-line therapy was significantly longer in de novo MBC in all but the triple-negative subtype, 25.5 vs 11.6 m (p < 0.001) among 390 patients with hormone receptor-positive, HER2-negative, 11.4 vs 5.4 m (p = 0.002) among 142 patients with HER2-positive, and 4.0 vs 3.0 m (p = 0.121) among 162 with triple-negative MBC. In multivariable analysis, de novo status remained independently associated with improved OS (hazard ratio 0.63, 95% CI 0.49–0.80), regardless of subtype and other features. Conclusion: Patients with de novo MBC have better outcomes than those with recurrent MBC. Differences in clinical subtype and response to therapy in the metastatic setting contribute to, but do not fully explain, this difference. Longer PFS to first-line therapy in de novo MBC suggests biologic differences compared to recurrent MBC, which may be intrinsic or due to acquired resistance from treatment for prior localized breast cancer in recurrent disease
School organizational culture: The peak of research in the context of neoliberal policies
Inscrita numa matriz teórica multirreferencial, a problemática da cultura organizacional tem sido objecto de múltiplos desenvolvimentos conceptuais e diversificadas apropriações políticas e ideológicas. No campo da educação e no contexto mais específico das organizações escolares, as abordagens culturais e simbólicas sofreram algumas inflexões teóricas apenas compreensíveis quando contextualizadas no quadro mais global das políticas internacionais de cariz neoliberal e neoconservador. Neste trabalho, procura-se reflectir criticamente sobre a forma como a problemática da cultura organizacional em contexto escolar passa a ser (re)perspectivada numa altura em que se expandem alguns objectivos e valores políticos associados às ideologias da modernização e da racionalização. Num segundo momento, tomando como ponto de partida a análise de um vasto número de investigações integradas em quatro bases de dados electrónicas de âmbito internacional, debatemos as principais tendências teóricas, conceptuais e metodológicas deste campo de estudo, fazendo sobressair o lugar e o estatuto da escola enquanto contexto privilegiado de investigação, designadamente nos domínios crítico-reflexivos.Within a multi-referential theoretical framework, the issue of organizational culture has been a subject for multiple conceptual developments and different ideological and political appropriations. In the field of education and in the specific context of school organizations, the cultural and symbolic approaches were subjected to some theoretical inflections. These can only be understood in the global framework of international policies of neoliberal and neoconservative nature. First, this paper critically discusses how the issue of organizational culture in school context was put in perspectives at a time when some political-ideological objectives and values were associated to modernization and rationalization ideologies. Based on the analysis of a great number of researches included in four electronic databases with an international scope, it then discusses the main theoretical, conceptual and methodological trends of this field of study, stressing the place and statute of school as a privileged research context, namely in the reflexive and critical domain.info:eu-repo/semantics/publishedVersio
Structure and oxidation kinetics of the Si(100)-SiO2 interface
We present first-principles calculations of the structural and electronic
properties of Si(001)-SiO2 interfaces. We first arrive at reasonable structures
for the c-Si/a-SiO2 interface via a Monte-Carlo simulated annealing applied to
an empirical interatomic potential, and then relax these structures using
first-principles calculations within the framework of density-functional
theory. We find a transition region at the interface, having a thickness on the
order of 20\AA, in which there is some oxygen deficiency and a corresponding
presence of sub-oxide Si species (mostly Si^+2 and Si^+3). Distributions of
bond lengths and bond angles, and the nature of the electronic states at the
interface, are investigated and discussed. The behavior of atomic oxygen in
a-SiO2 is also investigated. The peroxyl linkage configuration is found to be
lower in energy than interstitial or threefold configurations. Based on these
results, we suggest a possible mechanism for oxygen diffusion in a-SiO2 that
may be relevant to the oxidation process.Comment: 7 pages, two-column style with 6 postscript figures embedded. Uses
REVTEX and epsf macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/index.html#ng_sio
Safety outcomes during pediatric GH therapy: final results from the prospective GeNeSIS observational program
CONTEXT: Safety concerns regarding premature mortality, diabetes, neoplasia and cerebrovascular disease in association with growth hormone (GH) therapy have been raised.
OBJECTIVE: To assess incidence of key safety outcomes.
DESIGN: Prospective, multinational, observational study (1999-2015).
SETTING: 22,311 GH-treated children from 827 investigative sites in 30 countries.
PATIENTS: Children with growth disorders.
INTERVENTIONS: GH treatment.
MAIN OUTCOME MEASURES: Standardized mortality (SMR) and incidence (SIR) ratios with 95% confidence intervals (CI) for mortality, diabetes, and primary cancer, using general population registries.
RESULTS: Predominant short stature diagnoses were GH deficiency (63%), idiopathic short stature (13%), and Turner syndrome (8%), with mean±SD follow-up of 4.2±3.2 years (∼92,000 person-years [PY]). Forty-two deaths occurred in patients with follow-up, with SMR (95% CI) of 0.61 (0.44-0.82); the SMR was elevated for patients with cancer-related organic GH deficiency (5.87 [3.21-9.85]). Based on 18 cases, Type 2 diabetes (T2DM) risk was elevated (SIR 3.77 [2.24-5.96]), but 72% had risk factors. In patients without cancer history, 14 primary cancers were observed (SIR 0.71 [0.39-1.20]). Second neoplasms occurred in 31/622 (5.0%) cancer survivors (10.7 [7.5-15.2] cases/1000 PY), and intracranial tumor recurrences in 67/823 (8.1%) tumor survivors (16.9 [13.3-21.5] cases/1000 PY). All 3 hemorrhagic stroke cases had risk factors.
CONCLUSIONS: GeNeSIS data support the favourable safety profile of pediatric GH treatment. Overall risk for death or primary cancer was not elevated in GH-treated children, and no hemorrhagic strokes occurred in patients without risk factors. T2DM incidence was elevated compared to the general population, but most cases had diabetes risk factors
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