Toward a structural understanding of turbulent drag reduction: nonlinear coherent states in viscoelastic shear flows

Nontrivial steady flows have recently been found that capture the main structures of the turbulent buffer layer. We study the effects of polymer addition on these "exact coherent states" (ECS) in plane Couette flow. Despite the simplicity of the ECS flows, these effects closely mirror those observed experimentally: Structures shift to larger length scales, wall-normal fluctuations are suppressed while streamwise ones are enhanced, and drag is reduced. The mechanism underlying these effects is elucidated. These results suggest that the ECS are closely related to buffer layer turbulence.Comment: 5 pages, 3 figures, published version, Phys. Rev. Lett. 89, 208301 (2002

Short-term psychodynamic psychotherapy for functional somatic disorders: a systematic review and meta-analysis of within-treatment effects

OBJECTIVE: A recent meta-analysis of 17 randomized, controlled trials (RCTs) showed that Short-term Psychodynamic Psychotherapy (STPP) for functional somatic disorders (FSD) reduced somatic symptoms compared to wait list, minimal treatment, and treatment-as-usual controls. A clinically important yet unanswered question is how much improvement patients experience within STPP treatment. METHODS: Following a systematic search, we identified STPP trials presenting data at baseline and post-treatment/follow-up. Meta-analyses determined the magnitude of changes in somatic symptoms and other outcomes from before to after STPP, and analyses examined effect sizes as a function of study, therapy, and patient variables. RESULTS: We identified 37 trials (22 pre-post studies and 15 RCTs) totaling 2094 patients treated an average of 13.34 sessions for a range of FSD. Across all studies, somatic symptoms improved significantly from pre-treatment to short-term follow-up with a large effect size (SMD = −1.07), which was maintained at long-term follow-up (SMD = −0.90). After excluding two outlier studies, effects at short- and medium-term follow-up remained significant but were somewhat reduced in magnitude (e.g., short-term SMD = −0.73). Secondary outcomes including anxiety, depression, disability, and interpersonal problems had medium to large effects. Effects were larger for studies of STPP that were longer than 12 sessions or used an emotion-focused type of STPP, and for chronic pain or gastrointestinal conditions than for functional neurological disorders. CONCLUSIONS: STPP results in moderate to large improvements in multiple outcome domains that are sustained in long-term follow-up. STPP is an effective treatment option for FSD and should be included in treatment guidelines

Polymer transport in random flow

The dynamics of polymers in a random smooth flow is investigated in the framework of the Hookean dumbbell model. The analytical expression of the time-dependent probability density function of polymer elongation is derived explicitly for a Gaussian, rapidly changing flow. When polymers are in the coiled state the pdf reaches a stationary state characterized by power-law tails both for small and large arguments compared to the equilibrium length. The characteristic relaxation time is computed as a function of the Weissenberg number. In the stretched state the pdf is unstationary and exhibits multiscaling. Numerical simulations for the two-dimensional Navier-Stokes flow confirm the relevance of theoretical results obtained for the delta-correlated model.Comment: 28 pages, 6 figure

Computational case-based redesign for people with ability impairment: Rethinking, reuse and redesign learning for home modification practice

Home modification practice for people with impairments of ability involves redesigning existing residential environments as distinct from the creation of a new dwelling. A redesigner alters existing structures, fittings and fixtures to better meet the occupant's ability requirements. While research on case-based design reasoning and healthcare informatics are well documented, the reasoning and process of redesign and its integration with individual human functional abilities remains poorly understood. Developing a means of capturing redesign knowledge in the form of case documentation online provides a means for integrating and learning from individual case-based redesign episodes where assessment and interventions are naturally linked. A key aim of the research outlined in this thesis was to gain a better understanding of the redesign of spaces for individual human ability with the view to computational modelling. Consequently, the foundational knowledge underpinning the model development includes design, redesign, case-based building design and human functional ability. Case-based redesign as proposed within the thesis, is a method for capturing the redesign context, the residential environment, the modification and the transformational knowledge involved in the redesign. Computational simulation methods are traditionally field dependent. Consequently, part of the research undertaken within this thesis involved the development of a framework for analysing cases within an online case-studies library to validate redesign for individuals and a method of acquiring reuse information so as to be able to estimate the redesign needs of a given population based on either their environment or ability profile. As home modification for people with functional impairments was a novel application field, an explorative action-based methodological approach using computational modelling was needed to underpin a case-based reasoning method. The action-based method involved a process of articulating and examining existing knowledge, suggesting new case-based computational practices, and evaluating the results. This cyclic process led to an improvement cycle that included theory, computational tool development and practical application. The rapid explosion of protocols and online redesign communities that utilise Web technologies meant that a web-based prototype capable of acquiring cases directly from home modification practitioners online and in context was both desirable and achievable. The first online version in 1998-99, encoded home modification redesigns using static WebPages and hyperlinks. This motivated the full-scale more dynamic and robust HMMinfo casestudies prototype whose action-based development is detailed within this thesis. The home modification casestudies library results from the development and integration of a novel case-based redesign model in combination with a Human- Activity-Space computational ontology. These two models are then integrated into a relational database design to enable online case acquisition, browsing, case reuse and redesign learning. The application of the redesign ontology illustrates case reuse and learning, and presents some of the implementation issues and their resolution. Original contributions resulting from this work include: extending case-based design theory to encompass redesign and redesign models, distinguishing the importance of human ability in redesign and the development of the Human-Activity-Space ontology. Additionally all data models were combined and their associated inter-relationships evaluated within a prototype made available to redesign practitioners. v Reflective and practitioner based evaluation contributed enhanced understanding of redesign case contribution dynamics in an online environment. Feedback from redesign practitioners indicated that gaining informed consent to share cases from consumers of home modification and maintenance services, in combination with the additional time required to document a case online, and reticence to go public for fear of critical feedback, all contributed to a less than expected case library growth. This is despite considerable interest in the HMMinfo casestudies website as evidenced by web usage statistics. Additionally the redesign model described in this thesis has practical implications for all design practitioners and educators who seek to create new work by reinterpreting, reconstructing and redesigning spaces

Hysteresis phenomenon in turbulent convection

Coherent large-scale circulations of turbulent thermal convection in air have been studied experimentally in a rectangular box heated from below and cooled from above using Particle Image Velocimetry. The hysteresis phenomenon in turbulent convection was found by varying the temperature difference between the bottom and the top walls of the chamber (the Rayleigh number was changed within the range of $10^7 - 10^8$). The hysteresis loop comprises the one-cell and two-cells flow patterns while the aspect ratio is kept constant ($A=2 - 2.23$). We found that the change of the sign of the degree of the anisotropy of turbulence was accompanied by the change of the flow pattern. The developed theory of coherent structures in turbulent convection (Elperin et al. 2002; 2005) is in agreement with the experimental observations. The observed coherent structures are superimposed on a small-scale turbulent convection. The redistribution of the turbulent heat flux plays a crucial role in the formation of coherent large-scale circulations in turbulent convection.Comment: 10 pages, 9 figures, REVTEX4, Experiments in Fluids, 2006, in pres

The diet of young Neandertals from France, Pech de l’Azé I and Hortus II, reconstructed using dental microwear texture analysis

Les adultes néandertaliens présentent des différences de régime alimentaire en fonction de leur paléohabitat. Nous examinons si les jeunes enfants néandertaliens de France datant du stade isotopique marins 3 montrent également ces distinctions alimentaires à partir de l’étude de la texture des micro-usures dentaires des deuxièmes molaires déciduales des individus Pech de l’Azé I, datant d’une phase froide-tempérée, et Hortus II, datant d’une phase froid-aride extrême. L’échantillon comparatif (n=76) comprend des molaires déciduales d’agriculteurs-cueilleurs provenant de trois grottes néolithiques de Belgique, dont Caverne de la Cave à Maurenne (n=5), Sclaigneaux (n=7) et Bois Madame (n=6), ainsi que des agriculteurs de l’époque romaine d’Herculanum (n=15) et médiévaux de Canterbury, Angleterre (n=43). Lorsque la complexité est comparée à l’anisotropie, Pech de l’Azé I présente une valeur élevée provenant de la mastication de plantes à parties dures ou de particules adhérentes, ou de la consommation d’aliments mal transformés ou chargés de silicates abrasifs. En revanche, Hortus II a une valeur faible, peut-être en raison de l’accès limité aux parties dures des plantes comme les graines et les noix. Toutefois, Pech de l’Azé I et Hortus II se ressemblent en présentant une faible valeur d’anisotropie qui est révélatrice de mouvements complexes des mâchoires lors de la mastication et sont différents des enfants humains néolithiques, romains et médiévaux qui ont tendance à avoir des valeurs plus élevées. Les régimes alimentaires des enfants néandertaliens diffèrent en fonction du paléohabitat et sont généralement plus diversifiés que ceux des producteurs d’aliments, qu’ils habitent des environnements boisés ou ouverts.Neandertal adults show differences in diet with respect to paleohabitat. To examine whether Neandertal children of France during Marine Isotope Stage 3 also show these dietary distinctions, the deciduous second molars of Pech de l’Azé I, from a cold-temperate period, and Hortus II from Sub-Phase Vb, an extreme cold-arid interval, were examined using dental microwear texture analysis. The comparative sample (n=76) includes deciduous molars from Neolithic forager-farmers of Belgium, including Caverne de la Cave at Maurenne (n=5), Sclaigneaux (n=7) and Bois Madame (n=6), Roman-era farmers from Herculaneum (n=15) and Medieval agriculturalists from Canterbury, England (n=43). When complexity is compared to anisotropy, Pech de l’Azé I exhibits an elevated value from the mastication of plants with hard parts or adherent particles, or the consumption of foods that were poorly processed or grit-laden, whereas Hortus II presents a low value, perhaps from limited access to hard plant parts such as seeds and nuts. However, Pech de l’Azé I and Hortus II resemble each other in having a low value for anisotropy, which is indicative of complicated movements of the jaws during mastication and are dissimilar to Neolithic, Roman and Medieval human children who tend to have higher values. The diets of Neandertal children differ with respect to paleohabitat and typically were more diverse than those of food producers regardless of whether they inhabited wooded or open environments

Drug-gene interactions of antihypertensive medications and risk of incident cardiovascular disease: a pharmacogenomics study from the CHARGE consortium

Background Hypertension is a major risk factor for a spectrum of cardiovascular diseases (CVD), including myocardial infarction, sudden death, and stroke. In the US, over 65 million people have high blood pressure and a large proportion of these individuals are prescribed antihypertensive medications. Although large long-term clinical trials conducted in the last several decades have identified a number of effective antihypertensive treatments that reduce the risk of future clinical complications, responses to therapy and protection from cardiovascular events vary among individuals. Methods Using a genome-wide association study among 21,267 participants with pharmaceutically treated hypertension, we explored the hypothesis that genetic variants might influence or modify the effectiveness of common antihypertensive therapies on the risk of major cardiovascular outcomes. The classes of drug treatments included angiotensin-converting enzyme inhibitors, beta-blockers, calcium channel blockers, and diuretics. In the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, each study performed array-based genome-wide genotyping, imputed to HapMap Phase II reference panels, and used additive genetic models in proportional hazards or logistic regression models to evaluate drug-gene interactions for each of four therapeutic drug classes. We used meta-analysis to combine study-specific interaction estimates for approximately 2 million single nucleotide polymorphisms (SNPs) in a discovery analysis among 15,375 European Ancestry participants (3,527 CVD cases) with targeted follow-up in a case-only study of 1,751 European Ancestry GenHAT participants as well as among 4,141 African-Americans (1,267 CVD cases). Results Although drug-SNP interactions were biologically plausible, exposures and outcomes were well measured, and power was sufficient to detect modest interactions, we did not identify any statistically significant interactions from the four antihypertensive therapy meta-analyses (Pinteraction > 5.0×10−8). Similarly, findings were null for meta-analyses restricted to 66 SNPs with significant main effects on coronary artery disease or blood pressure from large published genome-wide association studies (Pinteraction ≥ 0.01). Our results suggest that there are no major pharmacogenetic influences of common SNPs on the relationship between blood pressure medications and the risk of incident CVD

The Red Sea, Coastal Landscapes, and Hominin Dispersals

This chapter provides a critical assessment of environment, landscape and resources in the Red Sea region over the past five million years in relation to archaeological evidence of hominin settlement, and of current hypotheses about the role of the region as a pathway or obstacle to population dispersals between Africa and Asia and the possible significance of coastal colonization. The discussion assesses the impact of factors such as topography and the distribution of resources on land and on the seacoast, taking account of geographical variation and changes in geology, sea levels and palaeoclimate. The merits of northern and southern routes of movement at either end of the Red Sea are compared. All the evidence indicates that there has been no land connection at the southern end since the beginning of the Pliocene period, but that short sea crossings would have been possible at lowest sea-level stands with little or no technical aids. More important than the possibilities of crossing the southern channel is the nature of the resources available in the adjacent coastal zones. There were many climatic episodes wetter than today, and during these periods water draining from the Arabian escarpment provided productive conditions for large mammals and human populations in coastal regions and eastwards into the desert. During drier episodes the coastal region would have provided important refugia both in upland areas and on the emerged shelves exposed by lowered sea level, especially in the southern sector and on both sides of the Red Sea. Marine resources may have offered an added advantage in coastal areas, but evidence for their exploitation is very limited, and their role has been over-exaggerated in hypotheses of coastal colonization