275 research outputs found
SupeRVol: Super-Resolution Shape and Reflectance Estimation in Inverse Volume Rendering
We propose an end-to-end inverse rendering pipeline called SupeRVol that
allows us to recover 3D shape and material parameters from a set of color
images in a super-resolution manner. To this end, we represent both the
bidirectional reflectance distribution function (BRDF) and the signed distance
function (SDF) by multi-layer perceptrons. In order to obtain both the surface
shape and its reflectance properties, we revert to a differentiable volume
renderer with a physically based illumination model that allows us to decouple
reflectance and lighting. This physical model takes into account the effect of
the camera's point spread function thereby enabling a reconstruction of shape
and material in a super-resolution quality. Experimental validation confirms
that SupeRVol achieves state of the art performance in terms of inverse
rendering quality. It generates reconstructions that are sharper than the
individual input images, making this method ideally suited for 3D modeling from
low-resolution imagery
Shaping Policy Change in Population Health: Policy Entrepreneurs, Ideas, and Institutions
Political realities and institutional structures are often ignored when gathering evidence to influence population health policies. If these policies are to be successful, social science literature on policy change should be integrated into the population health approach. In this contribution, drawing on the work of John W. Kingdon and related scholarship, we set out to examine how key components of the policy change literature could contribute towards the effective development of population health policies. Shaping policy change would require a realignment of the existing school of thought, where the contribution of population health seems to end at knowledge translation. Through our critical analysis of selected literature, we extend recommendations to advance a burgeoning discussion in adopting new approaches to successfully implement evidence-informed population health policies
Shaping Policy Change in Population Health: Policy Entrepreneurs, Ideas, and Institutions
Abstract
Political realities and institutional structures are often ignored when gathering evidence to influence population
health policies. If these policies are to be successful, social science literature on policy change should be
integrated into the population health approach. In this contribution, drawing on the work of John W. Kingdon
and related scholarship, we set out to examine how key components of the policy change literature could
contribute towards the effective development of population health policies. Shaping policy change would
require a realignment of the existing school of thought, where the contribution of population health seems to
end at knowledge translation. Through our critical analysis of selected literature, we extend recommendations
to advance a burgeoning discussion in adopting new approaches to successfully implement evidence-informed
population health policies
Biomechanical Evaluation of Recurrent Dissociation of Modular Humeral Prostheses
The purpose of the study was to evaluate the force and torque required to dissociate a humeral head from the unimplanted modular total shoulder replacement system from different manufacturers and to determine if load and torque to dissociation are reduced in the presence of bodily fluids. Impingement, taper contamination, lack of compressive forces, and interference of taper fixation by the proximal humerus have all been reported as possible causes for dissociation. Experimental values determined in this research were compared with literature estimates of dissociation force of the humeral head under various conditions to gain more understanding of the causes of recurrent dissociations of the humeral head. This study examined biomechanical properties under dry and wet conditions under clinically practiced methods. Mean load to dissociation (1513 N ± 508 N) was found to be greater than that exerted by the activities of daily living (578 N) for all implants studied. The mean torque to dissociation was (49.77 N·m ± 19.07 N·m). Analysis of R2 correlation coefficients and p-values (α = 0.05) did not show any significant correlation between dry/bovine, dry/wet, or wet/bovine for load, displacement, or torsional stiffness in the majority of tests performed. Wetting the taper with water or bovine serum did not reduce the dissociation force to a statistically significant degree. Torque and lack of compressive forces at the rotator cuff may be the cause of dissociation at values less than those of activities of daily living. Torque data are provided by this study, but further research is needed to fully appreciate the role of torque in recurrent dissociations
Using an engineered glutamate-gated chloride channel to silence sensory neurons and treat neuropathic pain at the source
Peripheral neuropathic pain arises as a consequence of injury to sensory neurons; the development of ectopic activity in these neurons is thought to be critical for the induction and maintenance of such pain. Local anaesthetics and anti-epileptic drugs can suppress hyperexcitability; however, these drugs are complicated by unwanted effects on motor, central nervous system and cardiac function, and alternative more selective treatments to suppress hyperexcitability are therefore required. Here we show that a glutamate-gated chloride channel modified to be activated by low doses of ivermectin (but not glutamate) is highly effective in silencing sensory neurons and reversing neuropathic pain-related hypersensitivity. Activation of the glutamate-gated chloride channel expressed in either rodent or human induced pluripotent stem cell-derived sensory neurons in vitro potently inhibited their response to both electrical and algogenic stimuli. We have shown that silencing is achieved both at nerve terminals and the soma and is independent of membrane hyperpolarization and instead likely mediated by lowering of the membrane resistance. Using intrathecal adeno-associated virus serotype 9-based delivery, the glutamate-gated chloride channel was successfully targeted to mouse sensory neurons in vivo, resulting in high level and long-lasting expression of the channel selectively in sensory neurons. This enabled reproducible and reversible modulation of thermal and mechanical pain thresholds in vivo; analgesia was observed for 3 days after a single systemic dose of ivermectin. We did not observe any motor or proprioceptive deficits and noted no reduction in cutaneous afferent innervation or upregulation of the injury marker ATF3 following prolonged glutamate-gated chloride channel expression. Established mechanical and cold pain-related hypersensitivity generated by the spared nerve injury model of neuropathic pain was reversed by ivermectin treatment. The efficacy of ivermectin in ameliorating behavioural hypersensitivity was mirrored at the cellular level by a cessation of ectopic activity in sensory neurons. These findings demonstrate the importance of aberrant afferent input in the maintenance of neuropathic pain and the potential for targeted chemogenetic silencing as a new treatment modality in neuropathic pain
FastMRI Prostate: A Publicly Available, Biparametric MRI Dataset to Advance Machine Learning for Prostate Cancer Imaging
The fastMRI brain and knee dataset has enabled significant advances in
exploring reconstruction methods for improving speed and image quality for
Magnetic Resonance Imaging (MRI) via novel, clinically relevant reconstruction
approaches. In this study, we describe the April 2023 expansion of the fastMRI
dataset to include biparametric prostate MRI data acquired on a clinical
population. The dataset consists of raw k-space and reconstructed images for
T2-weighted and diffusion-weighted sequences along with slice-level labels that
indicate the presence and grade of prostate cancer. As has been the case with
fastMRI, increasing accessibility to raw prostate MRI data will further
facilitate research in MR image reconstruction and evaluation with the larger
goal of improving the utility of MRI for prostate cancer detection and
evaluation. The dataset is available at https://fastmri.med.nyu.edu.Comment: 4 pages, 1 figur
Healthy Aging and Dementia: Two Roads Diverging in Midlife?
Dementia, particularly Alzheimer’s disease (AD), is a growing pandemic that presents profound challenges to healthcare systems, families, and societies throughout the world. By 2050, the number of people living with dementia worldwide could almost triple, from 47 to 132 million, with associated costs rising to $3 trillion. To reduce the future incidence of dementia, there is an immediate need for interventions that target the disease process from its earliest stages. Research programs are increasingly starting to focus on midlife as a critical period for the beginning of AD-related pathology, yet the indicators of the incipient disease process in asymptomatic individuals remain poorly understood. We address this important knowledge gap by examining evidence for cognitive and structural brain changes that may differentiate, from midlife, healthy aging and pathological AD-related processes. This review crystallizes emerging trends for divergence between the two and highlights current limitations and opportunities for future research in this area
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