1,433 research outputs found
Wearable device to assist independent living.
Older people increasingly want to remain living independently in their own homes. The aim of the ENABLE project is to develop a wearable device that can be used both within and outside of the home to support older people in their daily lives and which can monitor their health status, detect potential problems, provide activity reminders and offer communication and alarm services. In order to determine the specifications and functionality required for development of the device user surveys and focus groups were undertaken and use case analysis and scenario modeling carried out. The project has resulted in the development of a wrist worn device and mobile phone combination that can support and assist older and vulnerable wearers with a range of activities and services both inside and outside of their homes. The device is currently undergoing pilot trials in five European countries. The aim of this paper is to describe the ENABLE device, its features and services, and the infrastructure within which it operates
Spectral properties of zero temperature dynamics in a model of a compacting granular column
The compacting of a column of grains has been studied using a one-dimensional
Ising model with long range directed interactions in which down and up spins
represent orientations of the grain having or not having an associated void.
When the column is not shaken (zero 'temperature') the motion becomes highly
constrained and under most circumstances we find that the generator of the
stochastic dynamics assumes an unusual form: many eigenvalues become
degenerate, but the associated multi-dimensional invariant spaces have but a
single eigenvector. There is no spectral expansion and a Jordan form must be
used. Many properties of the dynamics are established here analytically; some
are not. General issues associated with the Jordan form are also taken up.Comment: 34 pages, 4 figures, 3 table
Self-Averaging, Distribution of Pseudo-Critical Temperatures and Finite Size Scaling in Critical Disordered Systems
The distributions of singular thermodynamic quantities in an ensemble
of quenched random samples of linear size at the critical point are
studied by Monte Carlo in two models. Our results confirm predictions of
Aharony and Harris based on Renormalization group considerations. For an
Ashkin-Teller model with strong but irrelevant bond randomness we find that the
relative squared width, , of is weakly self averaging. , where is the specific heat exponent and is the
correlation length exponent of the pure model fixed point governing the
transition. For the site dilute Ising model on a cubic lattice, known to be
governed by a random fixed point, we find that tends to a universal
constant independent of the amount of dilution (no self averaging). However
this constant is different for canonical and grand canonical disorder. We study
the distribution of the pseudo-critical temperatures of the ensemble
defined as the temperatures of the maximum susceptibility of each sample. We
find that its variance scales as and NOT as
R_\chi\sim 70R_\chi (T_c)\chiT_c(i,l)m_i(T_c,l)T_c(i,l)(T-T_c(i,l))/T_c$. This function is found to be universal and to behave
similarly to pure systems.Comment: 31 pages, 17 figures, submitted to Phys. Rev.
Dog ownership and physical activity: A review of the evidence
Background: Dog walking is a strategy for increasing population levels of physical activity (PA). Numerous cross-sectional studies of the relationship between dog ownership and PA have been conducted. The purpose was to review studies comparing PA of dog owners (DO) to nondog owners (NDO), summarize the prevalence of dog walking, and provide recommendations for research. Methods: A review of published studies (1990-2010) examining DO and NDO PA and the prevalence of dog walking was conducted (N = 29). Studies estimating the relationship between dog ownership and PA were grouped to create a pointestimate using meta-analysis. Results: Most studies were conducted in the last 5 years, were cross-sectional, and sampled adults from Australia or the United States. Approximately 60% of DO walked their dog, with a median duration and frequency of 160 minutes/week and 4 walks/week, respectively. Meta-analysis showed DO engage in more walking and PA than NDO and the effect sizes are small to moderate (d = 0.26 and d = 0.16, respectively). Three studies provided evidence of a directional relationship between dog ownership and walking. Conclusions: Longitudinal and interventional studies would provide stronger causal evidence for the relationship between dog ownership and PA. Improved knowledge of factors associated with dog walking will guide intervention research
Fluctuation-dissipation relations in the non-equilibrium critical dynamics of Ising models
We investigate the relation between two-time, multi-spin, correlation and
response functions in the non-equilibrium critical dynamics of Ising models in
d=1 and d=2 spatial dimensions. In these non-equilibrium situations, the
fluctuation-dissipation theorem (FDT) is not satisfied. We find FDT
`violations' qualitatively similar to those reported in various glassy
materials, but quantitatively dependent on the chosen observable, in contrast
to the results obtained in infinite-range glass models. Nevertheless, all FDT
violations can be understood by considering separately the contributions from
large wavevectors, which are at quasi-equilibrium and obey FDT, and from small
wavevectors where a generalized FDT holds with a non-trivial limit
fluctuation-dissipation ratio X. In d=1, we get X = 1/2 for spin observables,
which measure the orientation of domains, while X = 0 for observables that are
sensitive to the domain-wall motion. Numerical simulations in d=2 reveal a
unique X = 0.34 for all observables. Measurement protocols for X are discussed
in detail. Our results suggest that the definition of an effective temperature
Teff = T / X for large length scales is generically possible in non-equilibrium
critical dynamics.Comment: 26 pages, 10 figure
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
Quantum Tomography under Prior Information
We provide a detailed analysis of the question: how many measurement settings
or outcomes are needed in order to identify a quantum system which is
constrained by prior information? We show that if the prior information
restricts the system to a set of lower dimensionality, then topological
obstructions can increase the required number of outcomes by a factor of two
over the number of real parameters needed to characterize the system.
Conversely, we show that almost every measurement becomes informationally
complete with respect to the constrained set if the number of outcomes exceeds
twice the Minkowski dimension of the set. We apply the obtained results to
determine the minimal number of outcomes of measurements which are
informationally complete with respect to states with rank constraints. In
particular, we show that 4d-4 measurement outcomes (POVM elements) is enough in
order to identify all pure states in a d-dimensional Hilbert space, and that
the minimal number is at most 2 log_2(d) smaller than this upper bound.Comment: v3: There was a mistake in the derived finer upper bound in Theorem
3. The corrected upper bound is +1 to the earlier versio
Internalized HIV stigma predicts subsequent viremia in US HIV patients through depressive symptoms and antiretroviral therapy adherence
Objective:We sought to examine the prospective association between internalized HIV stigma and unsuppressed viral load and to investigate whether this relationship was sequentially mediated by depressive symptoms and antiretroviral therapy (ART) adherence.Design:Longitudinal study in a multisite observational clinical cohort.Methods:The Center for AIDS Research Network of Integrated Clinical Systems patient-reported outcomes survey measures internalized HIV stigma yearly using a four-item assessment (response scale 1 = strongly disagree to 5 = strongly agree). We obtained patient-reported outcome, lab, and appointment data from six center for AIDS research network of integrated clinical systems sites. We used multivariable logistic regression to examine the association between mean stigma and subsequent viremia. We then used Bayesian sequential mediation to fit a longitudinal sequential path model spanning four time points to test if depressive symptoms at T1and ART adherence at T2mediated the effect of stigma at T0on viral load at T3, adjusting for baseline covariates.Results:Between February 2016 and November 2018, 6859 patients underwent stigma assessment and were 81% cis-men, 38% Black, 16% Latinx, 32% heterosexual-identified, and 49% at least 50 years of age. Mean stigma level was 2.00 (SD 1.08). Stigma was significantly associated with subsequent viremia (adjusted odds ratio = 1.16, 95% confidence interval: 1.05-1.28, P = 0.004), as were younger age and Black race. The chained indirect effect from stigma to unsuppressed viral load through depressive symptoms and then adherence was significant (standardized β = 0.002; SD = 0.001).Conclusion:Internalized HIV stigma positively predicts subsequent viremia through depressive symptoms and ART adherence. Addressing the link between stigma and depressive symptoms could help improve viral suppression
Internalized HIV Stigma Predicts Suboptimal Retention in Care among People Living with HIV in the United States
HIV-related stigma is a known barrier to retention in care. However, no large-scale, multi-site studies have prospectively evaluated the effect of internalized stigma on retention in care. The Centers for AIDS Research Network of Integrated Clinical Systems (CNICS) cohort study integrates medical record and survey data from people living with HIV (PLWH) seen in HIV primary care clinics across the United States, and assesses internalized stigma yearly using a validated 4-item Likert scale. We used multivariable logistic regression models to evaluate associations between mean internalized stigma and two prospective retention in care outcomes: keeping the next primary care appointment and keeping all scheduled primary care appointments in the 12 months following stigma assessment. From February 2016 to November 2017, 5968 PLWH completed the stigma assessment and had adequate follow-up time. Mean stigma was 1.9 (standard deviation 1.08). Increased mean stigma scores were associated with decreased odds of attending the next primary care appointment [adjusted odds ratio (aOR) = 0.93, 95% confidence interval (CI) 0.88-0.99, p = 0.02], and all primary care appointments in the subsequent 12 months (aOR = 0.94, 95% CI 0.89-0.99, p = 0.02). In both models, younger age and Black race were also independently associated with suboptimal appointment attendance. There was no support for interactions between internalized stigma and covariates. Internalized HIV stigma had an independent negative effect on the odds of subsequent appointment attendance. This study highlights the importance of identifying even low levels of internalized stigma. Interventions to address internalized HIV stigma are critical to supporting retention in care and improving clinical outcomes
The Human Immunodeficiency Virus (HIV) Index: Using a Patient-Reported Outcome on Engagement in HIV Care to Explain Suboptimal Retention in Care and Virologic Control
Background: We investigated the prospective association between a brief self-report measure of engagement in human immunodeficiency virus (HIV) care (the Index of Engagement in HIV Care; hereafter "Index") and suboptimal retention and viral suppression outcomes. Methods: The Centers for AIDS Research Network of Integrated Clinical Systems cohort study combines medical record data with patient-reported outcomes from 8 HIV clinics in the United States, which from April 2016 to March 2017 included the 10-item Index. Multivariable logistic regression was used to estimate the risk and odds ratios of mean Index scores on 2 outcomes in the subsequent year: (1) not keeping ≥75% of scheduled HIV care appointments; and (2) for those with viral suppression at Index assessment, having viral load >200 copies/mL on ≥1 measurement. We also used generalized linear mixed models (GLMMs) to estimate the risk and odds ratios of appointment nonattendance or unsuppressed viral load at any given observation. We generated receiver operating characteristic curves for the full models overlaid with the Index as a sole predictor. Results: The mean Index score was 4.5 (standard deviation, 0.6). Higher Index scores were associated with lower relative risk of suboptimal retention (n = 2576; logistic regression adjusted risk ratio [aRR], 0.88 [95% confidence interval,. 87-.88]; GLMM aRR, 0.85 [.83-.87]) and lack of sustained viral suppression (n = 2499; logistic regression aRR, 0.75 [.68-.83]; GLMM aRR, 0.74 [.68-.80]). The areas under the receiver operating characteristic curve for the full models were 0.69 (95% confidence interval,. 67-.71) for suboptimal retention and 0.76 (.72-.79) for lack of sustained viral suppression. Conclusions: Index scores are significantly associated with suboptimal retention and viral suppression outcomes
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