Recent experimental, numerical and theoretical advances in turbulent Rayleigh-Bénard convection are presented. Particular emphasis is given to the physics and structure of the thermal and velocity ...boundary layers which play a key role for the better understanding of the turbulent transport of heat and momentum in convection at high and very high Rayleigh numbers. We also discuss important extensions of Rayleigh-Bénard convection such as non-Oberbeck-Boussinesq effects and convection with phase changes.
We relate the intermittent fluctuations of velocity gradients in turbulence to a whole range of local dissipation scales generalizing the picture of a single mean dissipation length. The statistical ...distribution of these local dissipation scales as a function of Reynolds number is determined in numerical simulations of forced homogeneous isotropic turbulence with a spectral resolution never applied before which exceeds the standard one by at least a factor of eight. The core of the scale distribution agrees well with a theoretical prediction. Increasing Reynolds number causes the generation of ever finer local dissipation scales. This is in line with a less steep decay of the large wave number energy spectra in the dissipation range. The energy spectrum for the highest accessible Taylor microscale Reynolds number Rlambda = 107 does not show a bottleneck.
Objective:
Using the negative reinforcement and common factors frameworks, this work assessed whether and how anxiety sensitivity, distress tolerance, and impulsivity relate to reasons for drinking ...(RFD) in a residential treatment sample with co-occurring alcohol use disorder and posttraumatic stress disorder (AUD-PTSD). Demographic differences were also examined. Method: Participants were 75 (52.0% male, 78.7% white) adults at a residential substance use treatment facility who met criteria for AUD-PTSD with 98.67% meeting criteria for one or more substance use disorders in addition to AUD. Participants completed measures of anxiety sensitivity, distress tolerance, impulsivity, RFD, and AUD-PTSD symptoms. Univariate and multivariate linear regression was used with and without controlling for demographic variables (i.e., age, race, and sex). Results: The positive and negative urgency facets of impulsivity were positively related to both negative affect and cue/craving response RFD with relations maintained after controlling for demographic variables and including PTSD symptom severity (βs .30−.51). There were no significant relations between impulsivity and social RFD. No facets of anxiety sensitivity or distress tolerance were significantly related to RFD domains. Conclusions: Findings suggest that the urgency facets of impulsivity are crucial in understanding negative affect and cue/craving RFD. However, anxiety sensitivity and distress tolerance are not related to RFD in this dually diagnosed AUD-PTSD sample. Treatment considerations and future directions are discussed.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Direct numerical simulations are carried out to study the flow structure and transport properties in turbulent Rayleigh–Bénard convection in a vertical cylindrical cell of aspect ratio one with an ...imposed axial magnetic field. Flows at the Prandtl number
$0.025$
and Rayleigh and Hartmann numbers up to
$10^{9}$
and
$1400$
, respectively, are considered. The results are consistent with those of earlier experimental and numerical data. As anticipated, the heat transfer rate and kinetic energy are suppressed by a strong magnetic field. At the same time, their growth with Rayleigh number is found to be faster in flows at high Hartmann numbers. This behaviour is attributed to the newly discovered flow regime characterized by prominent quasi-two-dimensional structures reminiscent of vortex sheets observed earlier in simulations of magnetohydrodynamic turbulence. Rotating wall modes similar to those in Rayleigh–Bénard convection with rotation are found in flows near the Chandrasekhar linear stability limit. A detailed analysis of the spatial structure of the flows and its effect on global transport properties is reported.
Following amputation, most amputees still report feeling the missing limb and often describe these feelings as excruciatingly painful. Phantom limb sensations (PLS) are useful while controlling a ...prosthesis; however, phantom limb pain (PLP) is a debilitating condition that drastically hinders quality of life. Although such experiences have been reported since the early 16th century, the etiology remains unknown. Debate continues regarding the roles of the central and peripheral nervous systems. Currently, the most posited mechanistic theories rely on neuronal network reorganization; however, greater consideration should be given to the role of the dorsal root ganglion within the peripheral nervous system. This Review provides an overview of the proposed mechanistic theories as well as an overview of various treatments for PLP.
The iconic Miller’s pyramid, proposed in 1989, characterizes 4 levels of assessment in medical education (“knows,” “knows how,” “shows how,” “does”). The framework has created a worldwide awareness ...of the need to have different assessment approaches for different expected outcomes of education and training. At the time, Miller stressed the innovative use of simulation techniques, geared at the third level (“shows how”); however, the “does” level, assessment in the workplace, remained a largely uncharted area.In the 30 years since Miller’s conference address and seminal paper, much attention has been devoted to procedures and instrument development for workplace-based assessment. With the rise of competency-based medical education (CBME), the need for approaches to determine the competence of learners in the clinical workplace has intensified. The proposal to use entrustable professional activities as a framework of assessment and the related entrustment decision making for clinical responsibilities at designated levels of supervision of learners (e.g., direct, indirect, and no supervision) has become a critical innovation of CBME at the “does” level.Analysis of the entrustment concept reveals that trust in a learner to work without assistance or supervision encompasses more than the observation of “doing” in practice (the “does” level). It implies the readiness of educators to accept the inherent risks involved in health care tasks and the judgment that the learner has enough experience to act appropriately when facing unexpected challenges. Earning this qualification requires qualities beyond observed proficiency, which led the authors to propose adding the level “is trusted” to the apex of Miller’s pyramid.
Background
Laparoscopic intraperitoneal mesh repair has become one of the most commonly performed minimally invasive procedures. Nevertheless, despite improved overall outcome, postoperative seroma ...formation remains the most frequent complication. Our objective was to investigate the effectiveness of cauterization of the hernia sac in terms of reducing the incidence of postoperative seroma formation.
Methods
A retrospective analysis of 94 patients who underwent standard laparoscopic intraperitoneal mesh repair without closure of the central defect (sIPOM) between June 2011 and December 2014 was conducted. In 20 of those cases, electric cauterization of the hernia sac was additionally performed (csIPOM). One-to-one propensity score analysis was conducted to overcome patient selection bias between the two surgical techniques. The case–control group was matched by gender, body mass index (BMI), patient comorbidities, and surface of the hernia defect. Patient demographics, pre- and postoperative pain score (using a ten-point Likert scale), operative data, and complications were collected. At follow-up, postoperative seroma, hernia recurrence, and chronic pain were evaluated.
Results
Patient demographics, hernia size, comorbidities, and BMI were similar between the two groups. The csIPOM patient group had significantly lower rate of seroma formation, compared to the sIPOM control csIPOM vs. sIPOM 0 vs. 25% (
n
= 5),
p
< 0.05. There was no difference noted regarding postoperative pain between the two techniques. Hernia recurrence rate was found to be higher in the sIPOM group csIPOM vs. sIPOM 0 vs 12.5% (
n
= 2),
p
< 0.05.
Conclusion
The present study confirms our hypothesis that laparoscopic sIPOM combined with electric cauterization of the hernia sac (csIPOM) significantly reduces the rate of postoperative seroma compared to the sIPOM technique in patients with ventral and incisional hernias. Further randomized trials are required to verify our findings.
Antimicrobial peptides have been evaluated as possible alternatives to traditional antibiotics. The translational potential of the antimicrobial peptide DGL13K was tested with focus on peptide ...toxicity and in vivo activity in two animal models. DGL13K was effective against Pseudomonas aeruginosa, Staphylococcus aureus and methicillin-resistant S. aureus with minimal bactericidal concentrations similar to the minimal inhibitory concentration. The peptide showed low toxicity to human red blood cells and HEK cells with median lethal dose around 1 mg/ml. The median lethal dose in greater wax moth larvae (Galleria mellonella) was about 125mg/kg while the peptide caused no skin toxicity in a mouse model. A novel high-throughput luminescence assay was used to test peptide activity in infected G. mellonella, thus reducing vertebrate animal use. DGL13K killed P. aeruginosa in both the G. mellonella model and a mouse burn wound infection model, with bacterial viability 3-10-fold lower than in untreated controls. Future experiments will focus on optimizing peptide delivery, dose and frequency to further improve the antibacterial effect.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study aimed at estimating total forest above-ground net change (ΔAGB; Gg) over five years (2014–2019) based on model-assisted estimation utilizing freely available satellite imagery. The study ...was conducted for a boreal forest area (approx. 1.4 Mha) in Norway where bi-temporal national forest inventory (NFI), Sentinel-2, and Landsat data were available. Biomass change was modelled based on a direct approach. The precision of estimates using only the NFI data in a basic expansion estimator was compared to four different alternative model-assisted estimates using 1) Sentinel-2 or Landsat data, and 2) using bi- or uni-temporal remotely sensed data.
We found that spaceborne optical data improved the precision of the purely field-based estimates by a factor of up to three. The most precise estimates were found for the model-assisted estimation using bi-temporal Sentinel-2 (standard error; SE = 1.7 Gg). However, the decrease in precision when using Landsat data was small (SE = 1.92 Gg). We also found that ΔAGB could be precisely estimated when remotely sensed data were available only at the end of the monitoring period.
We conclude that satellite optical data can considerably improve ΔAGB estimates, when repeated and coincident field data are available. The free availability, global coverage, frequent update, and long-term time horizon make data from programs such as Sentinel-2 and Landsat a valuable data source for consistent and durable monitoring of forest carbon dynamics.
•NFI, Sentinel-2, and Landsat data used for estimation of AGB change.•Using spaceborne optical data improved the precision of AGB change estimates.•Sentinel-2 data yielded the most precise estimates.•Landsat data were nearly as good as Sentinel-2 data.•Possibility to estimate AGB changes using uni-temporal remotely sensed data.
As a developing and immature technique, additive manufacturing (AM) shows some limitations: depending on material and process parameters so far, it usually results in parts with residual porosity, ...high residual stresses and a surface with a certain level of roughness. Due to its weaknesses and high production costs, AM is more preferably used when the fabricated parts have a high geometry complexity, the material used is very expensive, or the parts can offer additional performance. In order to allocate AM further in industry, a better understanding of the not well-investigated fatigue behavior is necessary. This work focuses on the influences of some general process parameters including laser power, scan speed, scan pattern and postmachining on the resulting fatigue properties of H13 tool steel specimens generated through powder bed fusion (PBF) technique. Results reveal that scan patterns influence fatigue properties by affecting the largest porous defect size and microstructure thus matrix strength. The degree of porosity or roughness resulting from the energy input and postmachining has a significant inferior impact on the fatigue strength. Neither porosity nor tensile properties show a single direct mathematic correlation with the fatigue properties.
PDF
