Influence of Goertler vortices spanwise wavelength on heat transfer rates

The boundary layer over concave surfaces can be unstable due to centrifugal forces, giving rise to Goertler vortices. These vortices create two regions in the spanwise direction—the upwash and downwash regions. The downwash region is responsible for compressing the boundary layer toward the wall, increasing the heat transfer rate. The upwash region does the opposite. In the nonlinear development of the Goertler vortices, it can be observed that the upwash region becomes narrow and the spanwise–average heat transfer rate is higher than that for a Blasius boundary layer. This paper analyzes the influence of the spanwise wavelength of the Goertler the heat transfer. The equation is written in vorticity-velocity formulation. The time integration is done via a classical fourth-order Runge-Kutta method. The spatial derivatives are calculated using high-order compact finite difference and spectral methods. Three different wavelengths are analyzed. The results show that steady Goertler flow can increase the heat transfer rates to values close to the values of turbulence, without the existence of a secondary instability. The geometry (and computation domain) are presented

One and two degrees-of-freedom Vortex-Induced Vibration experiments with yawed cylinders

Vortex-Induced Vibration (VIV) experiments were carried out with yawed cylinders. The purpose was to investigate the validity of the Independence Principle (IP) for properly describing the flow characteristics and the dynamics of structures subjected to oblique flow. Five yaw angles in relation to the direction perpendicular to the free stream velocity were tested, namely View the MathML sourceθ=0°,10°,20°,30° and 45°. Both the upstream and downstream orientations were tested. The models were mounted on a leaf spring apparatus that allows experiments with one or two degrees of freedom. The Reynolds numbers based on the component normal to the cylinder axis fell in the interval 3×103and the cylinder aspect ratio was L/D≈13L/D≈13 for all the experiments. Time histories of displacement and hydrodynamic forces were acquired. Considering only the component of the free stream which is normal to the cylinder axis, the results of amplitude and force coefficients agreed reasonably well with the non-yawed ones for yaw angles up to 20° for both one and two degrees-of-freedom experiments. This indicates the validity of the IP for this yaw angle range. For yaw angles larger than 20°, a decrease in the maximum amplitude was observed. The decrease in the oscillation amplitudes was related to a larger modulation in the phase shift between force and displacement. Differences in the results for upstream and downstream were observed and were more evident for the larger yaw angle. These differences can be associated to the asymmetric cylinder end conditions.

Non-Linear Analysis and Design of Synchronous Bearingless Multiphase Permanent Magnet Machines and Drives

A two-dimensional model to analyze the distribution of magnetic fields in the airgap of a PM electrical machines is studied. A numerical algorithm for non-linear magnetic analysis of multiphase surface-mounted PM machines with semi-closed slots is developed, based on the equivalent magnetic circuit method. By using a modular structure geometry, whose the basic element can be duplicated, it allows to design whatever typology of windings distribution. In comparison to a FEA, permits a reduction in computing time and to directly changing the values of the parameters in a user interface, without re-designing the model. Output torque and radial forces acting on the moving part of the machine can be calculated. In addition, an analytical model for radial forces calculation in multiphase bearingless Surface-Mounted Permanent Magnet Synchronous Motors (SPMSM) is presented. It allows to predict amplitude and direction of the force, depending on the values of torque current, of levitation current and of rotor position. It is based on the space vectors method, letting the analysis of the machine also during transients. The calculations are conducted by developing the analytical functions in Fourier series, taking all the possible interactions between stator and rotor mmf harmonic components into account and allowing to analyze the effects of electrical and geometrical quantities of the machine, being parametrized. The model is implemented in the design of a control system for bearingless machines, as an accurate electromagnetic model integrated in a three-dimensional mechanical model, where one end of the motor shaft is constrained to simulate the presence of a mechanical bearing, while the other is free, only supported by the radial forces developed in the interactions between magnetic fields, to realize a bearingless system with three degrees of freedom. The complete model represents the design of the experimental system to be realized in the laboratory.

Hydrodynamics and solid dosage form disintegration/dissolution : immediate release tablets and novel in situ polyelectrolyte gastroretentive drug delivery systems

Solid oral dosage form disintegration in the human stomach is a highly complex process dependent on physicochemical properties of the stomach contents as well as on physical variables such as hydrodynamics and mechanical stress. Understanding the role of hydrodynamics and forces in disintegration of oral solid dosage forms can help to improve in vitro disintegration testing and the predictive power of the in vitro test. The aim of this work was to obtain a deep understanding of the influence of changing hydrodynamic conditions on solid oral dosage form performance. Therefore, the hydrodynamic conditions and forces present in the compendial PhEur/USP disintegration test device were characterized using a computational fluid dynamics (CFD) approach. Furthermore, a modified device was developed and the hydrodynamic conditions present were simulated using CFD. This modified device was applied in two case studies comprising immediate release (IR) tablets and gastroretentive drug delivery systems (GRDDS). Due to the description of movement provided in the PhEur, the movement velocity of the basket-rack assembly follows a sinusoidal profile. Therefore, hydrodynamic conditions are changing continually throughout the movement cycle. CFD simulations revealed that the dosage form is exposed to a wide range of fluid velocities and shear forces during the test. The hydrodynamic conditions in the compendial device are highly variable and cannot be controlled. A new, modified disintegration test device based on computerized numerical control (CNC) technique was developed. The modified device can be moved in all three dimensions and radial movement is also possible. Simple and complex moving profiles can be developed and the influence of the hydrodynamic conditions on oral solid dosage form performance can be evaluated. Furthermore, a modified basket was designed that allows two-sided fluid flow. CFD simulations of the hydrodynamics and forces in the modified device revealed significant differences in the fluid flow field and forces when compared to the compendial device. Due to the CNC technique moving velocity and direction are arbitrary and hydrodynamics become controllable. The modified disintegration test device was utilized to examine the influence of moving velocity on disintegration times of IR tablets. Insights into the influence of moving speed, medium viscosity and basket design on disintegration times were obtained. An exponential relationship between moving velocity of the modified basket and disintegration times was established in simulated gastric fluid. The same relationship was found between the disintegration times and the CFD predicted average shear stress on the tablet surface. Furthermore, a GRDDS was developed based on the approach of an in situ polyelectrolyte complex (PEC). Different complexes composed of different grades of chitosan and carrageenan and different ratios of those were investigated for their swelling behavior, mechanical stability, and in vitro drug release. With an optimized formulation the influence of changing hydrodynamic conditions on the swelling behavior and the drug release profile was demonstrated using the modified disintegration test device. Both, swelling behavior and drug release, were largely dependent on the hydrodynamic conditions. Concluding, it has been shown within this thesis that the application of the modified disintegration test device allows for detailed insights into the influence of hydrodynamic conditions on solid oral dosage form disintegration and dissolution. By the application of appropriate test conditions, the predictive power of in vitro disintegration testing can be improved using the modified disintegration test device. Furthermore, CFD has proven a powerful tool to examine the hydrodynamics and forces in the compendial as well as in the modified disintegration test device. rn

In-vitro assessment of the forces generated by lingual fixed retainers

The aim of this article was to assess the effect of wire adaptation on the lingual surfaces of mandibular anterior teeth with 3 types of lingual retainers on the development of vertical and labiolingual forces.

Women And The Epistemologies Of Pleasure: An Analysis Of Female Sexual Appetites And Practices At Bucknell University

Using an epistemological and feminist lens, this thesis analyzes the political and social forces that actively construct both knowledge and ignorance around female sexual pleasure. It draws from interviews and a focus group, all conducted at Bucknell Unviersity to explore the journeys that women take to gain knowledge about sexual pleasure, and how the sources and cultural mores that women in the twenty-first century rely on or go up against in order to gain such knowledge are often limited, unauthorized or phallocentric. This aids in the construction and perpetuation of ignorance. This thesis looks at how women feel shame or enact self-censorship, regardless of their assertion of knowledge concerning their sexual appetites, which results in consequential ambivalence. For this reason, it concludes that more informed and educational conversations between peers, parents and partners need to take place. These conversations will help to ignite change and to raise awareness about the knowledge and ignorance surrounding female sexual pleasure, which would allow for more pleasurable experiences to take place generally and with a brief over view on Bucknell's campus specifically.

Solid-State Compatibilization of Immiscible Polymer Blends: Cryogenic Milling and Solid-State Shear Pulverization

The blending of common polymers allows for the rapid and facile synthesis of new materials with highly tunable properties at a fraction of the costs of new monomer development and synthesis. Most blends of polymers, however, are completely immiscible and separate into distinct phases with minimal phase interaction, severelydegrading the performance of the material. Cross-phase interactions and property enhancement can be achieved with these blends through reactive processing or compatibilizer addition. A new class of blend compatibilization relies on the mechanochemical reactions between polymer chains via solid-state, high energy processing. Two contrasting mechanochemical processing techniques are explored in this thesis: cryogenic milling and solid-state shear pulverization (SSSP). Cryogenic milling is a batch process where a milling rod rapidly impacts the blend sample while submerged within a bath of liquid nitrogen. In contrast, SSSP is a continuous process where blend components are subjected to high shear and compressive forces while progressing down a chilled twin-screw barrel. In the cryogenic milling study, through the application of a synthesized labeledpolymer, in situ formation of copolymers was observed for the first time. The microstructures of polystyrene/high-density polyethylene (PS/HDPE) blends fabricated via cryomilling followed by intimate melt-state mixing and static annealing were found to be morphologically stable over time. PS/HDPE blends fabricated via SSSP also showed compatibilization by way of ideal blend morphology through growth mechanisms with slightly different behavior compared to the cryomilled blends. The new Bucknell University SSSP instrument was carefully analyzed and optimized to produce compatibilized polymer blends through a full-factorial experiment. Finally, blends of varying levels of compatibilization were subjected to common material tests to determine alternative means of measuring and quantifying compatibilization,

Guidance for the preparation of neurological management guidelines by EFNS scientific task forces - revised recommendations 2012

This paper is meant to provide guidance to anyone wishing to write a neurological guideline for diagnosis or treatment, and is directed at the Scientist Panels and task forces of the European Federation of Neurological Societies (EFNS). It substitutes the previous guidance paper from 2004. It contains several new aspects: the guidance is now based on a change of the grading system for evidence and for the resulting recommendations, and has adopted The Grading of Recommendations, Assessment, Development and Evaluation system (GRADE). The process of grading the quality of evidence and strength of recommendations can now be improved and made more transparent. The task forces embarking on the development of a guideline must now make clearer and more transparent choices about outcomes considered most relevant when searching the literature and evaluating their findings. Thus, the outcomes chosen will be more critical, more patient-oriented and easier to translate into simple recommendations. This paper also provides updated practical recommendations for planning a guideline task force within the framework of the EFNS. Finally, this paper hopes to find the approval also by the relevant bodies of our future organization, the European Academy of Neurology.

Add a Dash of Rhetoric, a Pinch of Technical Communication, a Handful of Pedagogy, and Mix Well: Cookbooks and Recipes as Instructional Texts, and What Domestic Texts from 1870 to 1935 Can Teach Us About Technical Communication

Through the use of rhetoric centered on authority and risk avoidance, scientific method has co-opted knowledge, especially women's everyday and experiential knowledge in the domestic sphere. This, in turn, has produced a profound affect on technical communication in the present day. I am drawing on rhetorical theory to study cookbooks and recipes for their contributions to changes in instructional texts. Using the rhetorical lenses of metis (cunning intelligence), kairos (timing and fitness) and mneme (memory), I examine the way in which recipes and cookbooks are constructed, used and perceived. This helps me uncover lost voices in history, the voices of women who used recipes, produced cookbooks and changed the way instructions read. Beginning with the earliest cookbooks and recipes, but focusing on the pivotal temporal interval of 1870-1935, I investigate the writing and rhetorical forces shaping instruction sets and domestic discourse. By the time of scientific cooking and domestic science, everyday and experiential knowledge were being excluded to make room for scientific method and the industrial values of the public sphere. In this study, I also assess how the public sphere, via Cooperative Extension Services and other government agencies, impacted the domestic sphere, further devaluing everyday knowledge in favor of the public scientific model. I will show how the changes in the production of food, cookbooks and recipes were related to changes in technical communication. These changes had wide rippling effects on the field of technical communication. By returning to some of the tenets and traditions of everyday and experiential knowledge, technical communication scholars, practitioners and instructors today can find new ways to encounter technical communication, specifically regarding the creation of instructional texts. Bringing cookbooks, recipes and everyday knowledge into the classroom and the field engenders a new realm of epistemological possibilities.

New respiratory enterovirus and recombinant rhinoviruses among circulating picornaviruses

Rhinoviruses and enteroviruses are leading causes of respiratory infections. To evaluate genotypic diversity and identify forces shaping picornavirus evolution, we screened persons with respiratory illnesses by using rhinovirus-specific or generic real-time PCR assays. We then sequenced the 5 untranslated region, capsid protein VP1, and protease precursor 3CD regions of virus-positive samples. Subsequent phylogenetic analysis identified the large genotypic diversity of rhinoviruses circulating in humans. We identified and completed the genome sequence of a new enterovirus genotype associated with respiratory symptoms and acute otitis media, confirming the close relationship between rhinoviruses and enteroviruses and the need to detect both viruses in respiratory specimens. Finally, we identified recombinants among circulating rhinoviruses and mapped their recombination sites, thereby demonstrating that rhinoviruses can recombine in their natural host. This study clarifies the diversity and explains the reasons for evolution of these viruses.

Explaining the Long-Term Trend in Violent Crime: A Heuristic Scheme and Some Methodological Considerations

There has been a discontinuous but fairly persistent long-term decline in homicide rates in core European countries since about 1500. Since the 1950s, however, we observe an upward trend in violent crime not only in Europe but in almost all of the economically advanced nations that combine democratic political structures with free-market economies. The paper presents an explanatory scheme designed to account for both, the long decline and its apparent reversal. The theoretical model draws heavily upon ideas taken from the sociological work of Emile Durkheim and Norbert Elias—with some modifications and extensions. It seeks to integrate sociological and historical perspectives and to give due weight to both, structural and developmental forces. A key hypothesis is that the pacifying effects of the erosion of traditional collectivism can only be maintained to the extent by which “cooperative individualism” dominates over against the forces of “disintegrative individualism.” Some suggestions are made concerning the selection of appropriate indicators and the handling of methodological problems related to causal attribution.

Precision of fit and retention force of cast non-precious-crowns on standard titanium implant-abutment with different design and height

OBJECTIVE The cost-effectiveness of cast nonprecious frameworks has increased their prevalence in cemented implant crowns. The purpose of this study was to assess the effect of the design and height of the retentive component of a standard titanium implant abutment on the fit, possible horizontal rotation and retention forces of cast nonprecious alloy crowns prior to cementation. MATERIALS AND METHODS Two abutment designs were examined: Type A with a 6° taper and 8 antirotation planes (Straumann Tissue-Level RN) and Type B with a 7.5° taper and 1 antirotation plane (SICace implant). Both types were analyzed using 60 crowns: 20 with a full abutment height (6 mm), 20 with a medium abutment height (4 mm), and 20 with a minimal (2.5 mm) abutment height. The marginal and internal fit and the degree of possible rotation were evaluated by using polyvinylsiloxane impressions under a light microscope (magnification of ×50). To measure the retention force, a custom force-measuring device was employed. STATISTICAL ANALYSIS one-sided Wilcoxon rank-sum tests with Bonferroni-Holm corrections, Fisher's exact tests, and Spearman's rank correlation coefficient. RESULTS Type A exhibited increased marginal gaps (primary end-point: 55 ± 20 μm vs. 138 ± 59 μm, P < 0.001) but less rotation (P < 0.001) than Type B. The internal fit was also better for Type A than for Type B (P < 0.001). The retention force of Type A (2.49 ± 3.2 N) was higher (P = 0.019) than that of Type B (1.27 ± 0.84 N). Reduction in abutment height did not affect the variables observed. CONCLUSION Less-tapered abutments with more antirotation planes provide an increase in the retention force, which confines the horizontal rotation but widens the marginal gaps of the crowns. Thus, casting of nonprecious crowns with Type A abutments may result in clinically unfavorable marginal gaps.

Probing the Structure, Pseudorotation, and Radial Vibrations of Cyclopentane by Femtosecond Rotational Raman Coherence Spectroscopy

Femtosecond time-resolved Raman rotational coherence spectroscopy (RCS) is employed to determine accurate rotational, vibration–rotation coupling constants, and centrifugal distortion constants of cyclopentane (C⁵H¹⁰). Its lowest-frequency vibration is a pseudorotating ring deformation that interconverts 10 permutationally distinct but energetically degenerate “twist” minima interspersed by 10 “bent” conformers. While the individual twist and bent structures are polar asymmetric tops, the pseudorotation is fast on the time scale of external rotation, rendering cyclopentane a fluxionally nonpolar symmetric top molecule. The pseudorotational level pattern corresponds to a one-dimensional internal rotor with a pseudorotation constant Bps ≈ 2.8 cm⁻¹. The pseudorotational levels are significantly populated up to l = ± 13 at 298 K; <10% of the molecules are in the l = 0 level. The next-higher vibration is the “radial” ν²³ ring deformation mode at 273 cm⁻¹, which is far above the pseudorotational fundamental. Femtosecond Raman RCS measurements were performed in a gas cell at T = 293 K and in a pulsed supersonic jet at T ≈ 90 K. The jet cooling reduces the pseudorotational distribution to l < ±8 and eliminates the population of ν²³, allowing one to determine the rotational constant as A0 = B0 = 6484.930(11) MHz. This value is ∼300 times more precise than the previous value. The fit of the RCS transients reveals that the rotation–pseudorotation coupling constant αe,psB = −0.00070(1) MHz is diminutive, implying that excitation of the pseudorotation has virtually no effect on the B0 rotational constant of cyclopentane. The smallness of αe,psB can be realized when comparing to the vibration–rotation coupling constant of the ν²³ vibration, αe,23B = −9.547(1) MHz, which is about 10⁴ times larger.

Crack and powder cocaine federal legislation: A sentencing disparity and potential for policy improvement

Since its introduction into the United States in the 1980s, crack cocaine has been a harsh epidemic that has taken its toll on a countless number of people. This highly addictive, cheap and readily available drug of abuse has permeated many demographic sectors, mostly in low income, lesser educated, and urban communities. This epidemic of crack cocaine use in inner city areas across the Unites States has been described as an expression of economic marginality and “social suffering” coupled with the local and international forces of drug market economies (Agar 2003). As crack cocaine is a derivative of cocaine, it utilizes the psychoactive component of the drug, but delivers it in a much stronger, quicker, and more addictive fashion. This, coupled with its ready availability and cheap price has allowed for users to not only become very addicted very quickly, but to be subject to the stringent and sometimes unequal or inconsistent punishments for possession and distribution of crack-cocaine. ^ There are many public health and social ramifications from the abuse of crack-cocaine, and these epidemics appear to target low income and minority groups. Public health issues relating to the physical, mental, and economic strain will be addressed, as well as the direct and indirect effects of the punishments that come as a result of the disparity in penalties for cocaine and crack-cocaine possession and distribution. ^ Three new policies have recently been introduced into the United Stated Congress that actively address the disparity in sentencing for drug and criminal activities. They are, (1) Powder-Crack Cocaine Penalty Equalization Act of 2009, (HR 18, 111th Cong. 2009), (2) The Drug Sentencing Reform and Cocaine Kingpin Trafficking Act of 2009, (HR 265, 111th Cong. 2009) and (3) The Justice Integrity Act of 2009, (111th Cong. 2009). ^ Although they have only been initiated, if passed, they have potential to not only eliminate the crack-cocaine disparity, but to enact laws that help those affected by this epidemic. The final and overarching goal of this paper is to analyze and ultimately choose the ideal policy that would not only eliminate the cocaine and crack disparity regardless of current or future state statutes, but will provide the best method of rehabilitation, prevention, and justice. ^

Escape performance of temperate king scallop, Pecten maximus under ocean warming and acidification

Among bivalves, scallops are exceptional due to their capacity to escape from predators by swimming which is provided by rapid and strong claps that are produced by the phasic muscle interspersed with tonic muscle contractions. Based on the concept of oxygen and capacity-limited thermal tolerance, the following hypothesis was tested: ocean warming and acidification (OWA) would induce disturbances in aerobic metabolic scope and extracellular acid-case status and impair swimming performance in temperate scallops. Following long-term incubation under near-future OWA scenarios [20 vs. 10 °C (control) and 0.112 kPa CO2 (hypercapnia) vs. 0.040 kPa CO2 (normocapnic control)], the clapping performance and metabolic rates (MR) were measured in resting (RMR) and fatigued (maximum MR) king scallops, Pecten maximus, from Roscoff, France. Exposure to OA, either alone or combined with warming, left MR and swimming parameters such as the total number of claps and clapping forces virtually unchanged. Only the duration of the escape response was affected by OA which caused earlier exhaustion in hyper- than in normocapnic scallops at 10 °C. While maximum MR was unaffected, warm exposure increased RMR in both normocapnic and hypercapnic P. maximus resulting in similar Q 10 values of ~2.2. The increased costs of maintenance and the observation of strongly reduced haemolymph PO2 levels indicate that at 20 °C scallops have reached the upper thermal pejus range with unbalanced capacities for aerobic energy metabolism. As a consequence, warming to 20 °C decreased mean phasic force during escape performance until fatigue. The observed prolonged recovery time in warm incubated scallops might be a consequence of elevated metabolic costs at reduced oxygen availability in the warmth.