We study the effects of plasma β (the ratio of plasma pressure to magnetic pressure) on the evolution of kinetic plasma turbulence using fully kinetic particle-in-cell simulations of decaying ...turbulence. We find that the plasma β systematically affects spectra, measures of intermittency, decay rates of turbulence fluctuations, and partitioning over different channels of energy exchange. More specifically, an increase in plasma β leads to greater total heating, with proton heating preferentially more than electrons. Implications for achieving magnetosheath like temperature ratios are discussed.
The Society of Black Academic Surgeons (SBAS) sought to understand who constitutes its membership and obtain feedback to improve the organization.
SBAS conducted a 25-question survey amongst members.
...The response rate was 19 % (n = 132/685) with an even gender breakdown (male n = 64, female n = 68). The majority identified as Black or African American (85 %), followed by White (12 %). Fifty-two percent identified as trainees, while the rest were practicing surgeons specializing in burn/trauma/critical care (19 %), oncology (19 %), and general surgery (13 %). Half joined SBAS within the last 3 years. Satisfaction was reported at a mean of 3.7/5. Lack of awareness (41 %), time (13 %), or interest (5 %) limited committee participation. Networking (83 %), mentorship/sponsorship/allyship (71 %), and leadership development (46 %) were most valued benefits with job boards, webinars, and grants least valuable.
SBAS is a unique organization uniting both new and lifetime members and opportunities exist to enhance current membership and improve participation.
•SBAS is a diverse organization composed of members from various points within their careers.•SBAS provides unique opportunities for its members.•SBAS is positioned to address and provide opportunities to underrepresented minorities in their surgical training and careers.
Exact laws for evaluating cascade rates, tracing back to the Kolmogorov "4/5" law, have been extended to many systems of interest including magnetohydrodynamics (MHD), and compressible flows of the ...magnetofluid and ordinary fluid types. It is understood that implementations may be limited by the quantity of available data and by the lack of turbulence symmetry. Assessment of the accuracy and feasibility of such third-order (or Yaglom) relations is most effectively accomplished by examining the von Kármán–Howarth equation in increment form, a framework from which the third-order laws are derived as asymptotic approximations. Using this approach, we examine the context of third-order laws for incompressible MHD in some detail. The simplest versions rely on the assumption of isotropy and the presence of a well-defined inertial range, while related procedures generalize the same idea to arbitrary rotational symmetries. Conditions for obtaining correct and accurate values of the dissipation rate from these laws based on several sampling and fitting strategies are investigated using results from simulations. The questions we address are of particular relevance to sampling of solar wind turbulence by one or more spacecraft.
Magnetic reconnection in naturally occurring and laboratory settings often begins locally and elongates, or spreads, in the direction perpendicular to the plane of reconnection. Previous work has ...largely focused on current sheets with a uniform thickness, for which the predicted spreading speed for anti‐parallel reconnection is the local speed of the current carriers. We derive a scaling theory of three‐dimensional (3D) spreading of collisionless anti‐parallel reconnection in a current sheet with its thickness varying in the out‐of‐plane direction, both for spreading from a thinner to thicker region and a thicker to thinner region. We derive an expression for calculating the time it takes for spreading to occur for a current sheet with a given profile of its thickness. A key result is that when reconnection spreads from a thinner to a thicker region, the spreading speed in the thicker region is slower than both the Alfvén speed and the speed of the local current carriers by a factor of the ratio of thin to thick current sheet thicknesses. This is important because magnetospheric and solar observations have previously measured the spreading speed to be slower than previously predicted, so the present mechanism might explain this feature. We confirm the theory via a parametric study using 3D two‐fluid numerical simulations. We use the prediction to calculate the time scale for reconnection spreading in Earth's magnetotail during geomagnetic activity. The results are also potentially important for understanding reconnection spreading in solar flares and the dayside magnetopause of Earth and other planets.
Plain Language Summary
Magnetic reconnection is fundamental process in plasmas that converts magnetic energy into kinetic and thermal energy and is known to mediate eruptive solar flares and geomagnetic substorms that create the northern lights. The x‐line where magnetic reconnection occurs can elongate or spread over time in the direction normal to the plane of reconnection, and this trait has been observed in the laboratory, Earth's magnetosphere, and is thought to be related to the elongation of chromospheric ribbons during solar flares. This study presents a scaling theory of the three‐dimensional (3D) spreading of anti‐parallel magnetic reconnection in current sheets with thickness varying in the out‐of‐plane direction. A key result is that when reconnection spreads from a thinner to a thicker region, the spreading speed in the thicker region is slower than expected. This is important because magnetospheric and solar observations have observed slower spreading speeds than previously predicted, so the present mechanism might explain this feature. We confirm the theory with 3D numerical simulations and use the prediction to calculate the time scale for reconnection spreading in Earth's magnetotail during geomagnetic activity.
Key Points
We derive a theory of three‐dimensional spreading of collisionless anti‐parallel reconnection in current sheets with non‐uniform thickness
Spreading from a thinner to a thicker current sheet occurs slower than local electron and Alfvén speeds, a key prediction of the theory
We apply the theory to reconnection spreading in Earth's magnetotail and discuss potential implications for solar flare ribbons
ABSTRACT
We examine dissipation and energy conversion in weakly collisional plasma turbulence, employing in situ observations from the Magnetospheric Multiscale mission and kinetic particle-in-cell ...simulations of proton–electron plasma. A previous result indicated the presence of viscous-like and resistive-like scaling of average energy conversion rates – analogous to scalings characteristic of collisional systems. This allows for extraction of collisional-like coefficients of effective viscosity and resistivity, and thus also determination of effective Reynolds numbers based on these coefficients. The effective Reynolds number, as a measure of the available bandwidth for turbulence to populate various scales, links turbulence macroscale properties with kinetic plasma properties in a novel way.
Infant formulas, pediatric and adult nutritional products are being fortified with bovine lactoferrin (bLF) due to its beneficial impacts on immune development and gut health. Lactoferrin ...supplementation into these products requires an analytical method to accurately quantify the concentrations of bLF to meet global regulatory and quality standards.
To develop and validate a lactoferrin method capable of meeting the AOAC Standard Method Performance Requirements (SMPR requirements 2020.005).
Powder formula samples are extracted using warm dibasic phosphate buffer, pH 8, then centrifuged at 4 °C to remove insoluble proteins, fat, and other solids. The soluble fraction is further purified on a HiTrap heparin solid-phase extraction column to isolate bLF from interferences. Samples are filtered, then analyzed by LC-UV using a protein BEH C4 analytical column and quantitated via external calibrant.
The limit of quantitation (2 mg/100g), repeatability (2.0-4.8% RSD), recovery (92.1-97.7%) and analytical range (∼4-193 mg/100g) all meet the method requirements as stated in SMPR 2020.005 for lactoferrin.
The reported single lab validation results demonstrate the ability of this lactoferrin method to meet or exceed the method performance requirements to measure soluble, intact, non-denatured bLF in infant and adult nutritional powder formulas.
The use of a heparin affinity column to isolate lactoferrin from bovine milk products combined with a selective analytical chromatographic column provides suitable analyte specificity without requiring proprietary equipment or reagents.
Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated ...vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications.
We conducted a retrospective cohort study among Ontario residents aged ≥ 65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥ 65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations.
During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥ 65 years was 22% (95% confidence interval CI, -6%-42%) for all influenza-associated deaths, 25% (95% CI, 13%-37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%-31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively.
By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ~4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Glycerol monolaurate (GML), a monoglyceride found in human milk (HM), has antimicrobial properties against a broad spectrum of bacteria, viruses, and fungi. In this study, an LC-MS/MS method was ...developed and validated for quantifying GML in HM based on quantification of two distinct isomers, 1-monolaurin and 2-monolaurin. The method validation included assessments of selectivity (no interferences), linearity (r2 range of 0.9954– 0.9985 and 96 of 98 individual points having residual <15%), accuracy (average recovery of 96.4% across both isomers and a range of spiked levels), and precision (total GML repeatability 6.6% RSD and intermediate precision 9.7% RSD). This validated method was used to measure the concentration of GML in unpasteurized HM from 60 mothers and compared geographical locations (Cincinnati and Shanghai), lactation time (weeks 2 and 26), and self-reported maternal allergy status (yes or no). Our findings suggest GML concentration in unpasteurized HM is considerably lower than previously reported in a study characterizing pasteurized HM. The data reported here highlights a novel, validated method used to quantify GML in HM and identified no differences in total GML concentrations when comparing HM from different geographical locations, lactation times, and mother’s allergy status.
•Glycerol monolaurate can be quantitated in human milk using a novel LC-MS/MS method.•Two distinct isomers, 1- and 2-monolaurin, were quantifiable in human milk.•GML was not correlated to maternal geography, lactation stage, and allergy status.•Presented results represent the largest human milk GML study published to date.
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