An analysis of a swimmer’s passive wave resistance using experimental data and CFD simulations

The passive resistance of a swimmer on the free surface has previously been researched experimentally. The contribution of wave resistance to total drag for a swimmer with a velocity around 2.0 m.s-1 was found to vary from 5% for Vorontsov and Rumyantsev (2000), to 21 % for Toussaint et al. (2002) and up to 60% according to Vennell et al. (2006). The exact resistance breakdown of a swimmer remains unknown due to difficulties in the direct measurement of wave resistance. As noted by Sato and Hino (2010), this lack of experimental data makes it difficult to validate numerical simulations of swimmers on the free surface.This study is therefore aimed at presenting direct measurements of a swimmer’s total drag and wave resistance, along with the longitudinal wave cuts which may be used to validate numerical simulations. In this paper, experimental data of a swimmer’s resistance are presented at two different velocities (case 1 = 1.7 m.s-1 and case 2 = 2.1 m.s-1). Total drag was measured using force block dynamometers mounted on a custom-built tow rig (Webb et al., 2011). Moreover, a longitudinal wave cut method was used to directly evaluate wave resistance (Eggers, 1955).The two conditions tested were simulated using the open-source Computational Fluid Dynamics (CFD) code OpenFOAM (OpenFOAM® (2013)). The body geometry is a generic human form, morphed into the correct attitude and depth using the above- and under-water video footage recorded during the experiment. 3D Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations were performed using the Volume of Fluid (VOF) method to solve the air-water interface. A similar numerical technique was used by Banks (2013a) to assess the passive resistance of a swimmer. Two cases were simulated and the error in total drag compared to the experimental data was found to be 1 % and 22 % respectively. In this paper, the resistance components over a swimmer’s typical range of speeds are investigated and compared with the experimental dat

The contribution of executive dysfunction to memory impairment and confabulation in schizophrenia

Study 1. Using a cognitive-process approach, 25 schizophrenic patients were matched with 25 healthy volunteers and compared on tests of memory and executive function. The schizophrenia group was found to have a significant impairment in immediate memory with relatively spared long-delay and recognition memory. Memory deficits were irrespective of the encoding strategies used and were unrelated to chronicity. In addition, the schizophrenic patients performed worse than controls on tests of executive function which was supported by some significant correlations between aspects of memory and executive function. The pattern of performance resembled that found in patients with subcortical or frontal lesions. Study 2. To examine further executive aspects of memory, an attempt to demonstrate confabulation in schizophrenia was made. Twelve schizophrenic patients were matched with 12 volunteers, 8 of whom were normal healthy subjects, with the remained being depressed patients. The subjects were asked to recall a set of experimental narratives, with confabulation being defined as the recall of ideas not present in the narrative. Subjects were also examined on a number of neuropsychological tests and the patients were assessed on the Krawiecka scale. Variable amounts of confabulation were observed in all the schizophrenic patients while only one control subject confabulated. The form of confabulation differed from those observed in other patients in that the original ideas were spontaneously rearranged to produce new ones. Confabulation was found to be related to difficulties in suppressing inappropriate responses and formal thought disorder. Study 3. Three schizophrenic patients previously identified as confabulators, were intensively studied to establish the mechanisms of narrative confabulation in schizophrenia. Patients were administered experimental tasks as well as standard neuropsychological tests of memory and executive function. Assessment of current symptoms was made using the SANS and SAPS scales. The severity of cognitive impairment was found to reflect the severity of confabulation, but memory impairment was neither nor sufficient to account for confabulation. Within the spectrum of executive deficits, impairments in response suppression and response monitoring, but not planning or generation were consistently associated with confabulation. The findings from the experimental tasks suggest that faults occur at both input and output. At the input stage, narrative material is encoded in a disorganised manner while at the output stage, this disorganisation is compounded by faulty editing processes. Study 4. Four schizophrenic patients who were known confabulators with narrative material, were subjected to an experimental autobiographical questionnaire designed to establish whether schizophrenic patients confabulate in response to questions calling on the recollection of personal facts and events. In addition, a number of neuropsychological tests were administered and current symptoms was assessed with the SANS and SAPS scales. All patients were observed to confabulate to varying degrees, particularly in response to questions relating to personal episodes rather than facts. For two patients, personal delusional systems were found to play a role in confabulation by providing a framework on which to base certain confabulatory recollections. Memory impairment was not found to be a necessary component to autobiographical confabulation but deficits in response suppression and response monitoring were observed to be related to the verification process performed during this task. Study 5. In an attempt to establish which anatomical regions may be at fault in schizophrenia when patients are engaged in response suppression tasks, six normal subjects were studied using positron emission tomography (PET) to identify anatomical regions involved when performing the Hayling Test. Subjects were also required to perform a control condition in which they had to read out the last word of given sentences. Compared to the control task, response initiation was associated with left sided activation of the frontal operculum, inferior frontal gyrus, middle temporal gyrus and right anterior cingulate gyrus, whereas response suppression was associated with left frontal operculum, inferior frontal gyrus and right anterior cingulate gyrus activation only. The difference between the two parts of the Hayling Test was in the increased activation of the left middle temporal gyrus and the left inferior frontal region (Brodmann's area 44/6) during response initiation

An investigation into the steady state performance of several methods of series compensating electricity transmission lines

There are several methods of providing series compensation for transmission lines using power electronic switches. Four methods of series compensation have been examined in this thesis, the thyristor controlled series capacitor, a voltage sourced inverter series compensator using a capacitor as the series element, a current sourced inverter series compensator and a voltage sourced inverter using an inductor as the series element. All the compensators examined will provide a continuously variable series voltage which is controlled by the switching of the electronic switches. Two of the circuits will offer both capacitive and inductive compensation, the thyristor controlled series capacitor and the current sourced inverter series compensator. The other two will produce either capacitive or inductive series compensation. The thyristor controlled series capacitor offers the widest range of series compensation. However, there is a band of unavailable compensation between 0 and 1 pu capacitive compensation. Compared to the other compensators examined the harmonic content of the compensating voltage is quite high. An algebraic analysis showed that there is more than one state the thyristor controlled series capacitor can operate in. This state has the undesirable effect of introducing large losses. The voltage sourced inverter series compensator using a capacitor as the series element will provide only capacitive compensation. It uses two capacitors which increase the cost of the compensator significantly above the other three. This circuit has the advantage of very low harmonic distortion. The current sourced inverter series compensator will provide both capacitive and inductive series compensation. The harmonic content of the compensating voltage is second only to the voltage sourced inverter series compensator using a capacitor as the series element. The voltage sourced inverter series compensator using an inductor as the series element will only provide inductive compensation, and it is the least expensive compensator examined. Unfortunately, the harmonics introduced by this circuit are considerable

The Influence of Didymosphenia geminate on Fisheries Resources in Rapid Creek, South Dakota – An Eight Year History

The aquatic nuisance diatom Didymosphenia geminata was established in Rapid Creek in the Black Hills of South Dakota in 2002. Shortly thereafter, large declines (\u3e50%) of the naturalized brown trout Salmo trutta population were observed. We evaluated the influence of water resources and D. geminata on (1) declines in brown trout biomass, (2) changes in food resources, and (3) diet of brown trout in Black Hills streams. Drought conditions were largely responsible for trout declines in Black Hills streams. However, comparison of brown trout sizestructure between the pre-D. geminata and post-D. geminata periods revealed that juvenile brown trout abundance increased while adult abundance decreased in Rapid Creek. Changes in food resources in D. geminata-impacted areas were thought to favor juvenile brown trout and negatively impact adults. In the presence of D. geminata, macroinvertebrate abundance was composed of fewer, larger taxa and higher numbers of smaller taxa (i.e., chironomids). Brown trout in Rapid Creek consumed fewer ephemeropterans and a high amount of dipterans. Nonetheless, diet analysis showed that brown trout in Rapid Creek consumed as much or more prey than trout from two other streams unaffected by D. geminata. Moreover, relative weight of brown trout from Rapid Creek was high (\u3e100), implying that food availability was not limiting. These findings imply that D. geminata did not negatively impact feeding and condition of brown trout in Rapid Creek, although mechanisms affecting size-structure in Rapid Creek remain unknown

Discovering sustainability: A transition approach towards sustainable development

Abstract The concepts of transition and transition management offer a fruitful context for cooperation and debate among scientists, policy makers, and corporate actors. Transition management and transition approach in general provide an integrative approach to analyze and formulate an unconventional pathway towards sustainability. Transitions’ approach is not to achieve fixed goals, but to gradually work towards common ambitions through innovation, integration, and co-evolution. A transition to sustainability is an open-ended societal process of fundamental change in structure, culture and practices that comply with the sustainability values. In this paper we address not only what is a transitions’ approach, but also what transition management can offer to policy makers who position sustainability at the core of the development. Process-oriented tenets of transition management as well as propositions in face of global and local challenges to sustainability are analyzed

Scaling in Plasticity-Induced Cell-Boundary Microstructure: Fragmentation and Rotational Diffusion

We develop a simple computational model for cell boundary evolution in plastic deformation. We study the cell boundary size distribution and cell boundary misorientation distribution that experimentally have been found to have scaling forms that are largely material independent. The cell division acts as a source term in the misorientation distribution which significantly alters the scaling form, giving it a linear slope at small misorientation angles as observed in the experiments. We compare the results of our simulation to two closely related exactly solvable models which exhibit scaling behavior at late times: (i) fragmentation theory and (ii) a random walk in rotation space with a source term. We find that the scaling exponents in our simulation agree with those of the theories, and that the scaling collapses obey the same equations, but that the shape of the scaling functions depend upon the methods used to measure sizes and to weight averages and histograms

Neuroscience and end-of-life decisions. New anthropological challenges for constitutional law: «Is Human Nature the only science of man»?

Nowadays, neuroscience permits the unveiling of interior elements of hu-man beings - the perception of pain, the presence of consciousness and even the will - in the absence of external manifestations. Physicians, indeed, seem capable of measuring the true mental state of individuals and their inner world through an elec-troencephalography or a functional magnetic resonance imaging. This new frontier affects the world of law and places heavy demands for lawyers embroiled in end-of-life matters. The present paper focuses on the use of neuroscientific acquisitions within end-of-life decisions, aiming to highlight two risks embedded in this use: the utmost deference towards science and scientific authority and the maximization of self-determination. The paper will provide, at the beginning, a framework of case law and end-of-life regulatory attempts; it will follow the analysis of the main challenges posed to law by advances in neuroscience. In the latter part of this paper, we will of-fer food for thought on the role of neuroscience and - in a broader perspective - of science in law

Predicting university performance in psychology: the role of previous performance and discipline-specific knowledge

Recent initiatives to enhance retention and widen participation ensure it is crucial to understand the factors that predict students' performance during their undergraduate degree. The present research used Structural Equation Modeling (SEM) to test three separate models that examined the extent to which British Psychology students' A-level entry qualifications predicted: (1) their performance in years 1-3 of their Psychology degree, and (2) their overall degree performance. Students' overall A-level entry qualifications positively predicted performance during their first year and overall degree performance, but negatively predicted their performance during their third year. Additionally, and more specifically, students' A-level entry qualifications in Psychology positively predicted performance in the first year only. Such findings have implications for admissions tutors, as well as for students who have not studied Psychology before but who are considering applying to do so at university

Src homology 2 domain containing protein 5 (SH2D5) binds the breakpoint cluster region protein, BCR, and regulates levels of Rac1-GTP

SH2D5 is a mammalian-specific, uncharacterized adaptor-like protein that contains an N-terminal phosphotyrosine binding (PTB) domain and a C-terminal Src Homology 2 (SH2) domain. We show that SH2D5 is highly enriched in adult mouse brain, particularly in purkinjie cells in the cerebellum and the cornu ammonis of the hippocampus. Despite harboring two potential phosphotyrosine (pTyr) recognition domains, SH2D5 binds minimally to pTyr ligands, consistent with the absence of a conserved pTyr-binding arginine residue in the SH2 domain. Immunoprecipitation coupled to mass spectrometry (IP-MS) from cultured cells revealed a prominent association of SH2D5 with Breakpoint Cluster Region protein (BCR), a RacGAP that is also highly expressed in brain. This interaction occurred between the PTB domain of SH2D5 and an NxxF motif located within the N-terminal region of BCR. siRNA-mediated depletion of SH2D5 in a neuroblastoma cell line, B35, induced a cell rounding phenotype correlated with low levels of activated Rac1-GTP, suggesting that SH2D5 affects Rac1-GTP levels. Taken together, our data provide the first characterization of the SH2D5 signaling protein

Effect of PolyGlycopleX (PGX) consumption on blood lipid profiles in healthy, Low CVD risk overweight adults

Raised blood lipid levels are associated with a risk of a cardiovascular disease (CVD). Moderate reductions in several CVD factors such as total, low-density lipoprotein (LDL) cholesterol and non-high-density lipoprotein (non-HDL) cholesterol concentrations may be more effective in reducing overall risk than a major reduction in just one. A blind, randomised controlled trial was conducted with 120 healthy overweight (BMI 25–30) adults aged 25–70 years who were non-smokers, not diabetic and of low risk of cardiovascular disease, as assessed by the Framingham risk equation. Participants consumed 4.5 g PolyGlycopleX (PGX) as softgel capsules (PGXS) or 5 g PGX granules (PGXG) or 5 g rice flour (RF) with meals three times a day for 12 weeks. Total, LDL and non-HDL cholesterol were all significantly reduced (−6%, −5% and −3.5%, respectively) post the PGX granule treatment; however, PGX in softgel capsule form did not affect blood lipid profiles. Daily consumption of PGX granules in overweight low CVD risk adults produced lipid changes indicating a CVD preventative benefit