Toroidal Vortices in Resistive Magnetohydrodynamic Equilibria

Resistive steady states in toroidal magnetohydrodynamics (MHD), where Ohm's law must be taken into account, differ considerably from ideal ones. Only for special (and probably unphysical) resistivity profiles can the Lorentz force, in the static force-balance equation, be expressed as the gradient of a scalar and thus cancel the gradient of a scalar pressure. In general, the Lorentz force has a curl directed so as to generate toroidal vorticity. Here, we calculate, for a collisional, highly viscous magnetofluid, the flows that are required for an axisymmetric toroidal steady state, assuming uniform scalar resistivity and viscosity. The flows originate from paired toroidal vortices (in what might be called a ``double smoke ring'' configuration), and are thought likely to be ubiquitous in the interior of toroidally driven magnetofluids of this type. The existence of such vortices is conjectured to characterize magnetofluids beyond the high-viscosity limit in which they are readily calculable.Comment: 17 pages, 4 figure

Generalized XY Model

The methods of Lie algebras are used to construct and solve a generalization of the XY model

Spontaneous creation of non-zero angular momentum modes in tunnel-coupled two-dimensional degenerate Bose gases

We investigate the dynamics of two tunnel-coupled two-dimensional degenerate Bose gases. The reduced dimensionality of the clouds enables us to excite specific angular momentum modes by tuning the coupling strength, thereby creating striking patterns in the atom density profile. The extreme sensitivity of the system to the coupling and initial phase difference results in a rich variety of subsequent dynamics, including vortex production, complex oscillations in relative atom number and chiral symmetry breaking due to counter-rotation of the two clouds.Comment: 7 pages, 5 figure

Investigating the persistence of tick-borne pathogens via the R0 model

In the epidemiology of infectious diseases, the basic reproduction number,R0, has a number of important applications, most notably it can be used to predict whether a pathogen is likely to become established, or persist, in a given area. We used the R0 model to investigate the persistence of 3 tick-borne pathogens; Babesia microti, Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in an Apodemus sylvaticus-Ixodes ricinus system. The persistence of these pathogens was also determined empirically by screening questing ticks and wood mice by PCR. All 3 pathogens behaved differently in response to changes in the proportion of transmission hosts on which I. ricinus fed, the efficiency of transmission between the host and ticks and the abundance of larval and nymphal ticks found on small mammals. Empirical data supported theoretical predictions of the R0 model. The transmission pathway employed and the duration of systemic infection were also identified as important factors responsible for establishment or persistence of tick-borne pathogens in a given tick-host system. The current study demonstrates how the R0 model can be put to practical use to investigate factors affecting tick-borne pathogen persistence, which has important implications for animal and human health worldwide

Response to exercise rehabilitation in smoking and nonsmoking patients with intermittent claudication

AbstractBackgroundThe purpose was to compare the changes in claudication pain, ambulatory function, daily physical activity, peripheral circulation, and health-related quality of life following a program of exercise rehabilitation in smoking and nonsmoking patients with peripheral arterial disease (PAD) limited by intermittent claudication.Methods and resultsThirty-nine smokers (63 ± 4 pack-year smoking history; mean ± SE) and 46 nonsmokers (former smokers who had a 51 ± 7 pack-year smoking history who quit 14 ± 2 years prior to investigation) completed the study. The 6-month exercise rehabilitation program consisted of intermittent treadmill walking to near maximal claudication pain 3 days per week, with progressive increases in walking duration and intensity during the program. Measurements were obtained on each patient before and after rehabilitation. Following exercise rehabilitation the smokers and nonsmokers had similar improvements in these measures, as initial claudication distance increased by 119% in the smokers (P < .001) and by 97% in the nonsmokers (P < .001), and absolute claudication distance increased by 82% (P < .001) and 59% (P < .001) in the smokers and nonsmokers, respectively. Furthermore, exercise rehabilitation improved (P < .05) ambulatory function, daily physical activity, peripheral circulation, and health-related quality of life in the smokers and nonsmokers.ConclusionExercise rehabilitation is an effective therapy to improve functional independence in both smoking and nonsmoking patients with PAD limited by intermittent claudication. Therefore, smokers with intermittent claudication are prime candidates for exercise rehabilitation because their relatively low baseline physical function does not impair their ability to regain lost functional independence to levels similar to nonsmoking patients with PAD

Informed consent and medical ordeal: a qualitative study

Background Informed consent is a mainstay of clinical practice, with both moral and legal force. Material disclosure about extreme treatments, however, is unlikely to convey the full impact of the experience of treatment. Informed consent may be flawed under such cir-cumstances. Aims To compare expressed satisfaction with pre-treatment information to satisfaction af-ter experiencing autologous stem cell transplantation (ASCT) for recurrent lymphoma. Methods A qualitative, narrative-based cohort study has been conducted in a Teaching hospital Bone Marrow Transplant unit at Westmead Hospital, Sydney, Australia. The cohort consisted of ten transplant recipients and nine of their nominated lay carers. The Outcome measure was satisfaction expressed in narrative interviews at the time of transplantation and three months later. We used discourse analytic techniques to examine the narratives. Results Both patients and carers expressed high satisfaction with the information given by individual clinicians and by speakers at a formal Information Day held before transplanta-tion. At the first interview, neither patients nor carers commented much on the forthcom-ing ordeal of chemotherapy and bone marrow ablation, although all patients had under-gone previous chemotherapy. At the second interview, the ordeal dominated the narratives, and retrospective dissatisfaction with information was common. Conclusions This study suggests that information about treatment theories and protocols can be satisfactorily communicated, but personal experience of suffering defies communi-cation. This finding has serious implications for the practices involved in obtaining informed consent and for the very notion of informed consent. KEY WORDS Autologous stem cell transplantation; haematological malignancies; extreme treatment; medical communication; informed consent

Informed consent and medical ordeal: a qualitative study

Background Informed consent is a mainstay of clinical practice, with both moral and legal force. Material disclosure about extreme treatments, however, is unlikely to convey the full impact of the experience of treatment. Informed consent may be flawed under such cir-cumstances. Aims To compare expressed satisfaction with pre-treatment information to satisfaction af-ter experiencing autologous stem cell transplantation (ASCT) for recurrent lymphoma. Methods A qualitative, narrative-based cohort study has been conducted in a Teaching hospital Bone Marrow Transplant unit at Westmead Hospital, Sydney, Australia. The cohort consisted of ten transplant recipients and nine of their nominated lay carers. The Outcome measure was satisfaction expressed in narrative interviews at the time of transplantation and three months later. We used discourse analytic techniques to examine the narratives. Results Both patients and carers expressed high satisfaction with the information given by individual clinicians and by speakers at a formal Information Day held before transplanta-tion. At the first interview, neither patients nor carers commented much on the forthcom-ing ordeal of chemotherapy and bone marrow ablation, although all patients had under-gone previous chemotherapy. At the second interview, the ordeal dominated the narratives, and retrospective dissatisfaction with information was common. Conclusions This study suggests that information about treatment theories and protocols can be satisfactorily communicated, but personal experience of suffering defies communi-cation. This finding has serious implications for the practices involved in obtaining informed consent and for the very notion of informed consent. KEY WORDS Autologous stem cell transplantation; haematological malignancies; extreme treatment; medical communication; informed consent