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"Burr, J"
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A Randomized Trial Comparing Treatments for Varicose Veins
This trial of varicose-vein treatments showed no substantial differences in quality of life 6 months after ultrasound-guided foam sclerotherapy, endovenous laser ablation, or surgery, but disease-specific quality of life was slightly worse after foam treatment than after surgery.
Ultrasound-guided foam sclerotherapy and thermal ablation techniques such as endovenous laser ablation have become widely used alternatives to surgery for the treatment of varicose veins. Previous randomized trials and meta-analyses have shown these treatments to be effective in terms of short-term technical success and clinician-reported outcomes.
1
–
19
Clinical practice guidelines recommend the use of patient-reported quality of life to assess the outcomes of treatment of varicose veins.
20
Quality of life was a primary outcome measure in two small randomized trials that compared surgery and endovenous laser ablation,
5
,
9
but to our knowledge, it has not been assessed as a primary . . .
Journal Article
Physical Frailty and Cognitive Function among Older Chinese Adults: The Mediating Roles of Activities of Daily Living Limitations and Depression
AbstractBackgroundPhysical frailty and cognitive impairment are prevalent globally, particularly in China, which is experiencing an unprecedented aging of its large population. ObjectivesExamine the association between physical frailty and the level and rate of change of cognitive function, globally and by domain, among community-dwelling Chinese older adults, and quantify the mediation effects from activities of daily living (ADL) limitations and depressive symptoms. DesignLongitudinal. SettingChina Health and Retirement Longitudinal Study (2011–2018). Participants5,431 eligible adults aged ≥ 60 years with valid information on physical frailty. MeasurementsPhysical frailty, cognitive function, ADL limitations, and depressive symptoms were respectively assessed by frailty phenotypes, the Telephone Interview for Cognitive Status (episodic memory, executive function, and orientation), performance in six daily tasks, and the eight-item Center for Epidemiological Studies Depression Scale. Latent growth curve models were used to address the objectives. ResultsCompared to adults who were non-frail, those who were pre-frail (β = −0.06) and frail (β = −0.13) reported significantly worse global cognitive function and episodic memory (pre-frail: β = −0.05; frail: β = −0.14), executive function (pre-frail: β = −0.04, frail: β = −0.10), and orientation (pre-frail: β = −0.06; frail: β = −0.07) at baseline; those who were frail were more likely to experience faster decline in global cognitive function (β = 0.12) and episodic memory (β = 0.08). ADL limitations (β = −0.07) and depressive symptoms (β = −0.14) significantly mediated the association between physical frailty and the level of cognitive function, but not its rate of decline. ConclusionsIntervention strategies that help maintain cognitive function may benefit from early screening and assessment of physical frailty. For pre-frail and frail older Chinese adults, programs designed to help improve or maintain activities of daily living and reduce number of depressive symptoms may contribute to better cognitive performance.
Journal Article
Future space experiment platforms for astrobiology and astrochemistry research
Space experiments are a technically challenging but a scientifically important part of astrobiology and astrochemistry research. The International Space Station (ISS) is an excellent example of a highly successful and long-lasting research platform for experiments in space, that has provided a wealth of scientific data over the last two decades. However, future space platforms present new opportunities to conduct experiments with the potential to address key topics in astrobiology and astrochemistry. In this perspective, the European Space Agency (ESA) Topical Team Astrobiology and Astrochemistry (with feedback from the wider scientific community) identifies a number of key topics and summarizes the 2021 “ESA SciSpacE Science Community White Paper” for astrobiology and astrochemistry. We highlight recommendations for the development and implementation of future experiments, discuss types of in situ measurements, experimental parameters, exposure scenarios and orbits, and identify knowledge gaps and how to advance scientific utilization of future space-exposure platforms that are either currently under development or in an advanced planning stage. In addition to the ISS, these platforms include CubeSats and SmallSats, as well as larger platforms such as the Lunar Orbital Gateway. We also provide an outlook for in situ experiments on the Moon and Mars, and welcome new possibilities to support the search for exoplanets and potential biosignatures within and beyond our solar system.
Journal Article
Flow acceleration in an RDRE with gradual chamber constriction
Rotating detonation propulsion technologies have the potential to create highly efficient engines in a small form factor. However, the detonation dynamics and complex flowfields inside the combustion chamber are greatly dependent on geometry; in particular, the downstream nozzle design affects dynamics inside the combustion chamber. In this work, three-dimensional large eddy simulations of a gaseous methane–oxygen rotating detonation rocket engine are presented for two geometries. The geometries match experimental tests previously conducted at the Air Force Research Laboratory and are chosen to compare engine operation with and without a converging–diverging nozzle. It is shown that flow in the unconstricted chamber exceeds Mach 1 behind the generated oblique shock structure, but that the addition of a 4.4
∘
converging section results in supersonic flow existing only in the diverging section of the nozzle. The formation enthalpy of the flow is calculated inside the chamber and demonstrates that the difference in pressures and detonation structures associated with the chamber area constriction do not result in a significant change in energy released through combustion.
Journal Article
An introduction to patient-reported outcome measures in ophthalmic research
Clinical outcomes, such as quantifying the extent of visual field loss by automated perimetry, are valued highly by health professionals, but such measures do not capture the impact of the condition on a patient’s life. Patient-reported outcomes describe any report or measure of health reported by the patient, without external interpretation by a clinician or researcher. In this review, we discuss the value of the measures that capture this information (patient-reported outcome measures; PROMs), and why they are important to both the clinician and the researcher. We also consider issues around developing or selecting a PROM for ophthalmic research, the emerging challenges around conducting and reporting PROMs in clinical trials and highlight best practice for their use. Search terms for this review comprised: (1) (patient-reported outcomes OR patient-reported outcome measures) AND (2) randomised controlled trials AND (3) limited to ophthalmic conditions. These terms were expanded as follows: (((‘patients’(MeSH Terms) OR ‘patients’(All Fields) OR ‘patient’(All Fields)) AND (‘research report’(MeSH Terms) OR (‘research’(All Fields) AND ‘report’(All Fields)) OR ‘research report’(All Fields) OR ‘reported’(All Fields)) AND outcomes(All Fields)) OR ((‘patients’(MeSH Terms) OR ‘patients’(All Fields) OR ‘patient’(All Fields)) AND (‘research report’(MeSH Terms) OR (‘research’(All Fields) AND ‘report’(All Fields)) OR ‘research report’(All Fields) OR ‘reported’(All Fields) AND (‘outcome assessment (health care)’(MeSH Terms) OR (‘outcome’(All Fields) AND ‘assessment’(All Fields) AND ‘(health’(All Fields) AND ‘care)’(All Fields)) OR ‘outcome assessment (health care)’(All Fields) OR (‘outcome’(All Fields) AND ‘measures’(All Fields)) OR ‘outcome measures’(All Fields))) AND (‘randomized controlled trial’(Publication Type) OR ‘randomized controlled trials as topic’(MeSH Terms) OR ‘randomised controlled trials’(All Fields) OR ‘randomized controlled trials’(All Fields)) AND (ophth*(All Fields)). The authors also utilised the extensive non-ophthalmic literature and online resources relating to PROs and PROMs to inform this review.
Journal Article
Infrared nanoscopy and tomography of intracellular structures
Although techniques such as fluorescence-based super-resolution imaging or confocal microscopy simultaneously gather both morphological and chemical data, these techniques often rely on the use of localized and chemically specific markers. To eliminate this flaw, we have developed a method of examining cellular cross sections using the imaging power of scattering-type scanning near-field optical microscopy and Fourier-transform infrared spectroscopy at a spatial resolution far beyond the diffraction limit. Herewith, nanoscale surface and volumetric chemical imaging is performed using the intrinsic contrast generated by the characteristic absorption of mid-infrared radiation by the covalent bonds. We employ infrared nanoscopy to study the subcellular structures of eukaryotic (Chlamydomonas reinhardtii) and prokaryotic (Escherichia coli) species, revealing chemically distinct regions within each cell such as the microtubular structure of the flagellum. Serial 100 nm-thick cellular cross-sections were compiled into a tomogram yielding a three-dimensional infrared image of subcellular structure distribution at 20 nm resolution. The presented methodology is able to image biological samples complementing current fluorescence nanoscopy but at less interference due to the low energy of infrared radiation and the absence of labeling.Kanevche and colleagues present a combined imaging method employing scattering-type scanning near-field optical microscopy and Fourier-transform infrared spectroscopy to visualize the internal structures of cells. Demonstrating their method on eukaryotic and prokaryotic cells, they reveal chemically distinct regions of the cells.
Journal Article
Arterial stiffness results from eccentrically biased downhill running exercise
There is increasing evidence that select forms of exercise are associated with vascular changes that are in opposition to the well-accepted beneficial effects of moderate intensity aerobic exercise. To determine if alterations in arterial stiffness occur following eccentrically accentuated aerobic exercise, and if changes are associated with measures of muscle soreness.
Repeated measures experimental cohort.
Twelve (m=8/f=4) moderately trained (VO2max=52.2±7.4mlkg−1min−1) participants performed a downhill run at −12° grade using a speed that elicited 60% VO2max for 40min. Cardiovascular and muscle soreness measures were collected at baseline and up to 72h post-running.
Muscle soreness peaked at 48h (p=<0.001). Arterial stiffness similarly peaked at 48h (p=0.04) and remained significantly elevated above baseline through 72h.
Eccentrically accentuated downhill running is associated with arterial stiffening in the absence of an extremely prolonged duration or fast pace. The timing of alterations coincides with the well-documented inflammatory response that occurs from the muscular insult of downhill running, but whether the observed changes are a result of either systemic or local inflammation is yet unclear. These findings may help to explain evidence of arterial stiffening in long-term runners and following prolonged duration races wherein cumulative eccentric loading is high.
Journal Article
Characteristic timescales for detonation-based rocket propulsion systems
Characteristic timescales for rotating detonation rocket engines (RDREs) are described in this study. Traveling detonations within RDREs create a complex reacting flow field involving processes spanning a range of timescales. Specifically, characteristic times associated with combustion kinetics (detonation and deflagration), injection (e.g., flow recovery), flow (e.g., mixture residence time), and acoustic modes are quantified using first-principle analyses to characterize the RDRE-relevant physics. Three fuels are investigated including methane, hydrogen, and rocket-grade kerosene RP-2 for equivalence ratios from 0.25 to 3 and chamber pressures from 0.51 to 10.13 MPa, as well as for a case study with a standard RDRE geometry. Detonation chemical timescales range from 0.05 to 1000 ns for the induction and reaction times; detonation-based chemical equilibrium, however, spans a larger range from approximately 0.5 to
200
μ
s for the flow condition and fuel. This timescale sensitivity has implications regarding maximizing detonative heat release, especially with pre-detonation deflagration in real systems. Representative synthetic detonation wave profiles are input into a simplified injector model that describes the periodic choking/unchoking process and shows that injection timescales typically range from 5 to
50
μ
s depending on injector stiffness; for detonations and low-stiffness injectors, target reactant flow rates may not recover prior to the next wave arrival, preventing uniform mixing. This partially explains the detonation velocity deficit observed in RDREs, as with the standard RDRE analyzed in this study. Finally, timescales tied to chamber geometry including residence time are on the order of 100–10,000
μ
s and acoustic resonance times are 10–
1000
μ
s. Overall, this work establishes characteristic time and length scales for the relevant physics, a valuable step in developing tools to optimize future RDRE designs.
Journal Article
Grape Cultivar and Sap Culture Conditions Affect the Development of Xylella fastidiosa Phenotypes Associated with Pierce's Disease
Xylella fastidiosa is a xylem-limited bacterium in plant hosts and causes Pierce's disease (PD) of grapevines, which differ in susceptibility according to the Vitis species (spp.). In this work we compared X. fastidiosa biofilm formation and population dynamics when cultured in xylem saps from PD-susceptible and -resistant Vitis spp. under different conditions. Behaviors in a closed-culture system were compared to those in different sap-renewal cultures that would more closely mimic the physicochemical environment encountered in planta. Significant differences in biofilm formation and growth in saps from PD-susceptible and -resistant spp. were only observed using sap renewal culture. Compared to saps from susceptible V. vinifera, those from PD-resistant V. aestivalis supported lower titers of X. fastidiosa and less biofilm and V. champinii suppressed both growth and biofilm formation, behaviors which are correlated with disease susceptibility. Furthermore, in microfluidic chambers X. fastidiosa formed thick mature biofilm with three-dimensional (3-D) structures, such as pillars and mounds, in saps from all susceptible spp. In contrast, only small aggregates of various shapes were formed in saps from four out of five of the resistant spp.; sap from the resistant spp. V. mustangensis was an exception in that it also supported thick lawns of biofilm but not the above described 3-D structures typically seen in a mature biofilm from the susceptible saps. Our findings provide not only critical technical information for future bioassays, but also suggest further understanding of PD susceptibility.
Journal Article