83 research outputs found

    Mechanical Properties of Hydrated Acoustically Sensitive Alginate-Based Microcapsules Confined in a Microfluidic Device as a Function of Size and Composition

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    Understanding the mechanical properties of alginate-based microcapsules according to size and chemical composition allows researchers to zero in on the treatment and methods required to engineer optimized implantable alginate-based artificial cells for chemotherapy. Cross-linked medium viscosity alginate capsules ranging from 1.1% (w/v)-1.8% (w/v) in composition and 200 μm-1200 μm in size, encapsulating ultrasound contrast agents and blue dextran were compressed within a 40 μm high polydimethylsiloxane microfluidic device and subsequently examined using 2D microscopy for strain deformation aimed at the calculation of poisson ratios and volume loss postcompression. Results indicate a decrease in Poisson ratio as a function of alginate concentration, with statistically significant increases in Poisson ratios and percent volume loss as a function of size and composition. For an average of 120 s observation time post compression, in light of the volume loss correlated to the number of cross-links as a function of capsule size and alginate concentration, a strong case for the dominance of poroelasticity vs. viscoelasticity can be made. While there was a decrease in mean Poisson ratio as a function of concentration, at 1.8% (w/v) the mean strain value converged to 0.5, the theoretical ideal isotropic value associated with soft biological tissue

    Sustainable Development Goal 3

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    Sustainable Development Goals (SDGs) aim to develop a better and sustainable future for the world and the goals are part of an action plan to address poverty, hunger, health, gender equity and various pressing world issues. One of these goals looks at health and wellness. Ageing populations have become a crucial issue worldwide and this short monograph explores ageing and how the consequences of an ageing population may affect our health care system through the case study on Hong Kong's population. The book looks at several critical health issues related to ageing. The elderly, particularly those with low socioeconomic status, rely more on the acute-centric care rather than primary care. The book suggests that secondary care service may only be effective to limited extent as a healthcare measure and an optimum health care system should be one that focuses on primary care. The authors put forth a compelling argument for disease prevention and screening schemes and explain how they are more cost-effective and beneficial to the society and the system. This thoughtful book will provide beneficial insights into the relationship of ageing and sustainable development goals in the context of health and wellness for policy makers and healthcare professionals

    A CLOSER LOOK AT SHALE: REPRESENTATIVE ELEMENTARY VOLUME ANALYSIS WITH LABORATORY 3D X-RAY COMPUTED MICROTOMOGRAPHY AND NANOTOMOGRAPHY

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    ABSTRACT Though naturally occurring in many regions of the world, shale rock microstructure continues to be much of a mystery. Pore sizes may be very small, typically low 100s of nanometers and even below 10s of nanometers. It is thus very important to determine the volume size that must be examined to understand the oil reserves in a macroscopic shale rock formation, as the small features require a very high resolution imaging system, which usually come with limited field of view. This makes precise quantification of the microstructure a daunting challenge, especially when the analysis needs to be performed in 3D to capture the tortuous paths taken by the pores. The introduction of ultra-high resolution imaging systems is now shedding light on the problem, with the commercialization of precise laboratory x-ray imaging tools. Here, a novel suite of x-ray computed tomography systems is shown to provide unique insight into shale microstructure. Large volumes are measured with as high as sub-1 m resolution using laboratory-based x-ray computed microtomography (VersaXRM) to localize regions-of-interest (ROIs) for further higher resolution analysis. A ROI of cubic volume with ~65 m on each side is isolated for precise analysis with a novel laboratorybased x-ray computed nanotomography system (UltraXRM) capable of 50 nm resolution for quantification of porosity within the shale sample. Using the multi-length scale resolution imaging systems described here, a representative elementary volume (REV) quantification has been performed, which identifies ~30 m as the minimum volume that must be considered in order to quantify pores in shale down to 150 nm linear dimensions. Using a 3D field of view capable of sampling ~4 of these REVs, a precise microstructure analysis is carried out, within which further calculations of pore tortuosity and connectivity are demonstrated. The non-destructive nature of x-ray imaging further opens the door to innovative experimentation, such as time-evolution and studies of microstructure response to varying environmental parameters, such as temperature cycling or surfactant treatment

    Sustainable Development Goal 3

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    Sustainable Development Goals (SDGs) aim to develop a better and sustainable future for the world and the goals are part of an action plan to address poverty, hunger, health, gender equity and various pressing world issues. One of these goals looks at health and wellness. Ageing populations have become a crucial issue worldwide and this short monograph explores ageing and how the consequences of an ageing population may affect our health care system through the case study on Hong Kong's population. The book looks at several critical health issues related to ageing. The elderly, particularly those with low socioeconomic status, rely more on the acute-centric care rather than primary care. The book suggests that secondary care service may only be effective to limited extent as a healthcare measure and an optimum health care system should be one that focuses on primary care. The authors put forth a compelling argument for disease prevention and screening schemes and explain how they are more cost-effective and beneficial to the society and the system. This thoughtful book will provide beneficial insights into the relationship of ageing and sustainable development goals in the context of health and wellness for policy makers and healthcare professionals

    Acute Effects of Tai Chi Training on Cognitive and Cardiovascular Responses in Late Middle-Aged Adults: A Pilot Study

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    This study explored the immediate effects of Tai Chi (TC) training on attention and meditation, perceived stress level, heart rate, oxygen saturation level in blood, and palmar skin temperature in late middle-aged adults. Twenty TC practitioners and 20 nonpractitioners volunteered to join the study. After baseline measurements were taken, the TC group performed TC for 10 minutes while their cognitive states and cardiovascular responses were concurrently monitored. The control group rested for the same duration in a standing position. Both groups were then reassessed. The participants’ attention and meditation levels were measured using electroencephalography; stress levels were measured using Perceived Stress Scale; heart rate and blood oxygenation were measured using an oximeter; and palmar skin temperature was measured using an infrared thermometer. Attention level tended to increase during TC and dropped immediately thereafter (p<0.001). Perceived stress level decreased from baseline to posttest in exclusively the TC group (p=0.005). Heart rate increased during TC (p<0.001) and decreased thereafter (p=0.001). No significant group, time, or group-by-time interaction effects were found in the meditation level, palmar skin temperature, and blood oxygenation outcomes. While a 10-minute TC training could temporarily improve attention and decrease perceived stress levels, it could not improve meditation, palmar skin temperature, or blood oxygenation among late middle-aged adults

    Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

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    Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P &lt; 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

    Characteristics of Adults in the Hepatitis B Research Network in North America Reflect Their Country of Origin and Hepatitis B Virus Genotype

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    Chronic hepatitis B virus (HBV) infection is an important cause of cirrhosis and hepatocellular carcinoma worldwide; populations that migrate to the US and Canada might be disproportionately affected. The Hepatitis B Research Network (HBRN) is a cooperative network of investigators from the United States and Canada, created to facilitate clinical, therapeutic, and translational research in adults and children with hepatitis B. We describe the structure of the network and baseline characteristics of adults with hepatitis B enrolled in the network

    Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

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    Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

    Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M&gt;70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0&lt;e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level
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