49 research outputs found
Perceived stress levels of individuals who practice yoga in comparison to individuals who participate in other forms of exercise
This study explored if the perceived stress levels of individuals was influenced by the activity they engaged in, yoga or other forms of exercise. Additionally, factors of practicing yoga or another from of exercise were examined to determine their influence on perceived stress such as length of time, frequency, form, and longevity of the activity. The sample was found using a nonpropability convince sample in addition to snowball sampling. Participants consisted of 85 individuals (75% white), however only 50 participants qualified as well as completed all questions on the Perceived Stress Scale and thus were the only individuals considered. Participants completed the Perceived Stress Scale assessment in addition to several questions in regards to participants\u27 yoga or other form of exercise habits such as duration, frequency, longevity, and form of preferred activity. Inferential statistics were utilized to compare the perceived stress scores of individuals who participated in yoga with individuals who engaged in other forms of exercise. This study found that individuals who practice yoga have significantly lower perceived stress levels than individuals who engage in other forms of exercise. Due to the limited sample size (N=50) there was no significant relationship found between perceived stress level and duration, longevity, frequency and form of activity
Dynamic critical behavior of failure and plastic deformation in the random fiber bundle model
The random fiber bundle (RFB) model, with the strength of the fibers
distributed uniformly within a finite interval, is studied under the assumption
of global load sharing among all unbroken fibers of the bundle. At any fixed
value of the applied stress (load per fiber initially present in the bundle),
the fraction of fibers that remain unbroken at successive time steps is shown
to follow simple recurrence relations. The model is found to have stable fixed
point for applied stress in the range 0 and 1; beyond which total failure of
the bundle takes place discontinuously. The dynamic critical behavior near this
failure point has been studied for this model analysing the recurrence
relations. We also investigated the finite size scaling behavior. At the
critical point one finds strict power law decay (with time t) of the fraction
of unbroken fibers. The avalanche size distribution for this mean-field
dynamics of failure has been studied. The elastic response of the RFB model has
also been studied analytically for a specific probability distribution of fiber
strengths, where the bundle shows plastic behavior before complete failure,
following an initial linear response.Comment: 13 pages, 5 figures, extensively revised and accepted for publication
in Phys. Rev.
Precursors of catastrophe in the BTW, Manna and random fiber bundle models of failure
We have studied precursors of the global failure in some self-organised
critical models of sand-pile (in BTW and Manna models) and in the random fiber
bundle model (RFB). In both BTW and Manna model, as one adds a small but fixed
number of sand grains (heights) to any central site of the stable pile, the
local dynamics starts and continues for an average relaxation time (\tau) and
an average number of topplings (\Delta) spread over a radial distance (\xi). We
find that these quantities all depend on the average height (h_{av}) of the
pile and they all diverge as (h_{av}) approaches the critical height (h_{c})
from below: (\Delta) (\sim (h_{c}-h_{av}))(^{-\delta}), (\tau \sim
(h_{c}-h_{av})^{-\gamma}) and (\xi) (\sim) ((h_{c}-h_{av})^{-\nu}). Numerically
we find (\delta \simeq 2.0), (\gamma \simeq 1.2) and (\nu \simeq 1.0) for both
BTW and Manna model in two dimensions. In the strained RFB model we find that
the breakdown susceptibility (\chi) (giving the differential increment of the
number of broken fibers due to increase in external load) and the relaxation
time (\tau), both diverge as the applied load or stress (\sigma) approaches the
network failure threshold (\sigma_{c}) from below: (\chi) (\sim) ((\sigma_{c})
(-)(\sigma)^{-1/2}) and (\tau) (\sim) ((\sigma_{c}) (-)(\sigma)^{-1/2}). These
self-organised dynamical models of failure therefore show some definite
precursors with robust power laws long before the failure point. Such
well-characterised precursors should help predicting the global failure point
of the systems in advance.Comment: 13 pages, 9 figures (eps
Incidence of WHO stage 3 and 4 conditions following initiation of Anti-Retroviral Therapy in resource limited settings
To determine the incidence of WHO clinical stage 3 and 4 conditions during early anti-retroviral therapy (ART) in resource limited settings (RLS)
High order amplitude equation for steps on creep curve
We consider a model proposed by one of the authors for a type of plastic
instability found in creep experiments which reproduces a number of
experimentally observed features. The model consists of three coupled
non-linear differential equations describing the evolution of three types of
dislocations. The transition to the instability has been shown to be via Hopf
bifurcation leading to limit cycle solutions with respect to physically
relevant drive parameters. Here we use reductive perturbative method to extract
an amplitude equation of up to seventh order to obtain an approximate analytic
expression for the order parameter. The analysis also enables us to obtain the
bifurcation (phase) diagram of the instability. We find that while
supercritical bifurcation dominates the major part of the instability region,
subcritical bifurcation gradually takes over at one end of the region. These
results are compared with the known experimental results. Approximate analytic
expressions for the limit cycles for different types of bifurcations are shown
to agree with their corresponding numerical solutions of the equations
describing the model. The analysis also shows that high order nonlinearities
are important in the problem. This approach further allows us to map the
theoretical parameters to the experimentally observed macroscopic quantities.Comment: LaTex file and eps figures; Communicated to Phys. Rev.
Dopaminergic Neuronal Imaging in Genetic Parkinson's Disease: Insights into Pathogenesis
Objectives:To compare the dopaminergic neuronal imaging features of different subtypes of genetic Parkinson's Disease.Methods:A retrospective study of genetic Parkinson's diseases cases in which DaTSCAN (123I-FP-CIT) had been performed. Specific non-displaceable binding was calculated for bilateral caudate and putamen for each case. The right:left asymmetry index and striatal asymmetry index was calculated.Results:Scans were available from 37 cases of monogenetic Parkinson's disease (7 glucocerebrosidase (GBA) mutations, 8 alpha-synuclein, 3 LRRK2, 7 PINK1, 12 Parkin). The asymmetry of radioligand uptake for Parkinson's disease with GBA or LRRK2 mutations was greater than that for Parkinson's disease with alpha synuclein, PINK1 or Parkin mutations.Conclusions:The asymmetry of radioligand uptake in Parkinsons disease associated with GBA or LRRK2 mutations suggests that interactions with additional genetic or environmental factors may be associated with dopaminergic neuronal loss
Recommended from our members
Evaluating the Benefits of Aphasia Intervention Delivered in Virtual Reality: Results of a Quasi-Randomised Study
Introduction
This study evaluated an intervention for people with aphasia delivered in a novel virtual reality platform called EVA Park. EVA Park contains a number of functional and fantastic locations and allows for interactive communication between multiple users. Twenty people with aphasia had 5 weeks’ intervention, during which they received daily language stimulation sessions in EVA Park from a support worker. The study employed a quasi randomised design, which compared a group that received immediate intervention with a waitlist control group. Outcome measures explored the effects of intervention on communication and language skills, communicative confidence and feelings of social isolation. Compliance with the intervention was also explored through attrition and usage data.
Results
There was excellent compliance with the intervention, with no participants lost to follow up and most (18/20) receiving at least 88% of the intended treatment dose. Intervention brought about significant gains on a measure of functional communication. Gains were achieved by both groups of participants, once intervention was received, and were well maintained. Changes on the measures of communicative confidence and feelings of social isolation were not achieved. Results are discussed with reference to previous aphasia therapy findings
Condensation of bosons in kinetic regime
We study the kinetic regime of the Bose-condensation of scalar particles with
weak self-interaction. The Boltzmann equation is solved
numerically. We consider two kinetic stages. At the first stage the condensate
is still absent but there is a nonzero inflow of particles towards and the distribution function at grows from finite
values to infinity in a finite time. We observe a profound similarity between
Bose-condensation and Kolmogorov turbulence. At the second stage there are two
components, the condensate and particles, reaching their equilibrium values. We
show that the evolution in both stages proceeds in a self-similar way and find
the time needed for condensation. We do not consider a phase transition from
the first stage to the second. Condensation of self-interacting bosons is
compared to the condensation driven by interaction with a cold gas of fermions;
the latter turns out to be self-similar too. Exploiting the self-similarity we
obtain a number of analytical results in all cases.Comment: 23 pages plus 11 uuencoded figures, LaTeX, REVTEX 3.0 versio