Structure parameters in rotating Couette-Poiseuille channel flow

It is well-known that a number of steady state problems in fluid mechanics involving systems of nonlinear partial differential equations can be reduced to the problem of solving a single operator equation of the form: v + lambda Av + lambda B(v) = 0, v is the summation of H, lambda is the summation of one-dimensional Euclid space, where H is an appropriate (real or complex) Hilbert space. Here lambda is a typical load parameter, e.g., the Reynolds number, A is a linear operator, and B is a quadratic operator generated by a bilinear form. In this setting many bifurcation and stability results for problems were obtained. A rotating Couette-Poiseuille channel flow was studied, and it showed that, in general, the superposition of a Poiseuille flow on a rotating Couette channel flow is destabilizing

A selection principle in Benard-type convection

In a Benard-type convection problem, the stationary flows of an infinite layer of fluid lying between two rigid horizontal walls and heated uniformly from below are determined. As the temperature difference across the layer increases beyond a certain value, other convective motions appear. These motions areoften cellular in character in that their streamlines are confined to certain well-defined cells having, for example, the shape of rolls or hexagons. A selection principle that explains why hexagonal cells seem to be preferred for certain ranges of the parameters is formulated. An operator-theoretical formulation of one generalized Bernard problem is given. The infinite dimensional problem is reduced to one of solving a finite dimensional system of equations, namely, the selection equations. These equations are solved and a linearized stability analysis of the resultant stationary flows is presented

A Brief History of Quality Improvement in Health Care and Spinal Surgery.

While medical and technological advances continue to shape and advance health care, there has been growing emphasis on translating these advances into improvement in overall health care quality outcomes in the United States. Innovators such as Abraham Flexner and Ernest Codman engaged in rigorous reviews of systems and patient outcomes igniting wider spread interest in quality improvement in health care. Codman\u27s efforts even contributed to the founding of the American College of Surgeons. This society catalyzed a quality improvement initiative across the United States and the formation of the Joint Commission on Accreditation of Hospitals. Since that time, those such as Avedis Donabedian and the Institute of Medicine have worked to structure the process of improving both the quality and delivery of health care. Significant advances include the defining of minimum standards for hospital accreditation, 7 pillars of quality in medicine, and the process by which quality in medicine is evaluated. All of these factors have affected current practice more each day. In a field such as spinal surgery, cost and quality measures are continually emphasized and led to large outcome databases to better evaluate outcomes in complex, heterogeneous populations. Going forward, these databases will be instrumental in developing practice patterns and improving spinal surgery outcomes

Impact of Denial of Service Attacks on Ad Hoc Networks

Significant progress has been made towards making ad hoc networks secure and DoS resilient. However, little attention has been focused on quantifying DoS resilience: Do ad hoc networks have sufficiently redundant paths and counter-DoS mechanisms to make DoS attacks largely ineffective? Or are there attack and system factors that can lead to devastating effects? In this paper, we design and study DoS attacks in order to assess the damage that difficult-to-detect attackers can cause. The first attack we study, called the JellyFish attack, is targeted against closed-loop flows such as TCP; although protocol compliant, it has devastating effects. The second is the Black Hole attack, which has effects similar to the JellyFish, but on open-loop flows. We quantify via simulations and analytical modeling the scalability of DoS attacks as a function of key performance parameters such as mobility, system size, node density, and counter-DoS strategy. One perhaps surprising result is that such DoS attacks can increase the capacity of ad hoc networks, as they starve multi-hop flows and only allow one-hop communication, a capacity- maximizing, yet clearly undesirable situation

Production benefits of childhood overhearing

The current study assessed whether overhearing Spanish during childhood helps later Spanish pronunciation in adulthood. Our preliminary report based on a subset of the data [Au et al., Psychol. Sci. 13, 238-243 (2002)] revealed that adults who overheard Spanish during childhood had better Spanish pronunciation, but not better morphosyntax, than adult learners of Spanish who had no childhood experience with Spanish. We now present data from the full sample with additional morphosyntax and pronunciation assessments, as well as measures to help rule out possible confounding prosodic factors such as speech rate, phrasing, and stress placement. Three groups of undergraduates were compared: 15 Spanish-English bilinguals (native Spanish speakers), 15 late learners of Spanish who overheard Spanish during childhood (childhood overhearers), 15 late learners of Spanish who had no regular experience with Spanish until middle or high school (typical late L2 learners). Results confirmed a pronunciation advantage for the childhood overhearers over the typical late L2 learners on all measures: phonetic analyses (VOT and degree of lenition), accent ratings (phoneme and story production), but no benefit in morphosyntax. Importantly, the pronunciation advantage did not seem attributable to prosodic factors. These findings illustrate the specificity of overhearers' advantage to phonological production. © 2003 Acoustical Society of America.published_or_final_versio

Cogeneration Technology Alternatives Study (CTAS). Volume 5: Cogeneration systems results

The use of various advanced energy conversion systems is examined and compared with each other and with current technology systems for savings in fuel energy, costs, and emissions in individual plants and on a national level. About fifty industrial processes from the largest energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum based residual and distillate liquid fuels, and low Btu gas obtained through the on site gasification of coal. The methodology and results of matching the cogeneration energy conversion systems to approximately 50 industrial processes are described. Results include fuel energy saved, levelized annual energy cost saved, return on investment, and operational factors relative to the noncogeneration base cases

Effectiveness of adult community-based physical activity interventions with objective physical activity measurements and long-term follow-up: a systematic review and meta-analysis.

OBJECTIVE: To identify randomised controlled trials (RCTs) of physical activity (PA) interventions with objective PA outcomes in adults and to evaluate whether intervention effects were sustained beyond 12 months. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Seven databases (Medline, Embase, PsycINFO, Web of Science, Cochrane library, CINAHL (Cumulative Index of Nursing and Allied Health Literature) and ASSIA (Applied Social Sciences Index and Abstracts)) were searched from January 2000 until December 2019. ELIGIBILITY CRITERIA: RCTs reporting objective PA outcomes beyond 12 months with community-based participants aged ≥18 years were included; those where controls received active interventions, including advice to increase PA levels, were excluded. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers completed extraction of aggregate data and assessed risk of bias. Meta-analyses used random-effects models at different follow-up points. Primary outcomes were daily steps and weekly minutes of moderate-to-vigorous PA (MVPA). RESULTS: Of 33 282 records identified, nine studies (at generally low risk of bias) were included, five in meta-analyses with 12 months to 4 year follow-up. We observed 12 month increases for intervention vs control participants in steps/day (mean difference (MD)=554 (95% CIs: 384 to 724) p<0.0001, I2=0%; 2446 participants; four studies) and weekly MVPA minutes (MD=35 (95% CI: 27 to 43) p<0.0001, I2=0%; 2647 participants; four studies). Effects were sustained up to 4 years for steps/day (MD=494 (95% CI: 251 to 738) p<0.0001, I2=0%; 1944 participants; four studies) and weekly MVPA minutes (MD=25 (95% CI: 13 to 37) p<0.0001, I2=0%; 1458 participants; three studies). CONCLUSIONS: There are few PA interventions with objective follow-up beyond 12 months, more studies are needed. However, this review provided evidence of PA intervention effects beyond 12 months and sustained up to 4 years for both steps/day and MVPA. These findings have important implications for potential long-term health benefits. PROSPERO REGISTRATION NUMBER: CRD42017075753