Leaf Temperatures in a Gas Exchange Chamber and in the Open Air

Leaf temperatures in a Koch fully climatized gas-exchange chamber as designed by Siemens and in a similarly equipped open-air reference were measured with horizontally and vertically inserted thermocouples on Nerium oleander L. On a sunny day with only little air movement and an average air temperature of 20.4 °C, leaf over-temperatures in the gas-exchange chamber were lower on average by 2.2 K. The extent of reduction of over-temperature in the chamber is determined by the reduced global radiation in the chamber and the differences of wind velocities in chamber and reference. Differences in the ventilation intensity in the chamber have no demonstrable influence on the leaf over-temperatures. The over-temperatures of the reference leaves, on the other hand, depend to a large degree on air velocity. The changed radiation and air flow conditions in the chamber as compared with open-air conditions have consequences for the physiological reactions of the enclosed plant and must be taken into account when comparing results from gas-exchange measurements with open-air conditions. For further improvements of gas-exchange measurement equipment, air flow conditions and radiation quantity and quality might be starting point

Sonoluminescing air bubbles rectify argon

The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water soluble gases implies that strongly forced air bubbles eventually consist of pure argon. Thus it is the partial argon (or any other inert gas) pressure which is relevant for stability. The theory provides quantitative explanations for many aspects of SBSL.Comment: 4 page

Bubble Shape Oscillations and the Onset of Sonoluminescence

An air bubble trapped in water by an oscillating acoustic field undergoes either radial or nonspherical pulsations depending on the strength of the forcing pressure. Two different instability mechanisms (the Rayleigh--Taylor instability and parametric instability) cause deviations from sphericity. Distinguishing these mechanisms allows explanation of many features of recent experiments on sonoluminescence, and suggests methods for finding sonoluminescence in different parameter regimes.Comment: Phys. Rev. Lett., in pres

Convergence of Discretized Light Cone Quantization in the small mass limit

I discuss the slow convergence of Discretized Light Cone Quantization (DLCQ) in the small mass limit and suggest a solution.Comment: 8 pages, 5 Postscript figures, uses boxedeps.te

Electromagnetic duality and light-front coordinates

We review the light-front Hamiltonian approach for the Abelian gauge theory in 3+1 dimensions, and then study electromagnetic duality in this framework.Comment: 18 pages, LaTeX, 2 references and a typo in an eqn. (19) corrected, minor revisions in response to referee's repor

Short cephalomedullary nail toggle: a closer examination

Objectives: In patients with wide femoral canals, an undersized short nail may not provide adequate stability, leading to toggling of the nail around the distal interlocking screw and subsequent loss of reduction. The purpose of this study was to identify risk factors associated with nail toggle and to examine whether increased nail toggle is associated with increased varus collapse. Design: Retrospective cohort study. Setting: Level 1 and level 3 trauma center. Patients/Participants: Seventy-one patients with intertrochanteric femur fractures treated with short cephalomedullary nails (CMN) from October 2013 to December 2017. Intervention: Short CMN. Main Outcome Measurements: Nail toggle and varus collapse were measured on intraoperative and final follow-up radiographs. Risk factors for nail toggle including demographics, fracture classification, quality of reduction, Dorr type, nail/canal diameter ratio, lag screw engaging the lateral cortex, and tip-apex distance (TAD) were recorded. Results: On multivariate regression analysis, shorter TAD (P = .005) and smaller nail/canal ratio (P \u3c .001) were associated with increased nail toggle. Seven patients (10%) sustained nail toggle \u3e4 degrees. They had a smaller nail/canal ratio (0.54 vs 0.74, P \u3c .001), more commonly Dorr C (57% vs 14%, P = .025), lower incidence of lag screw engaging the lateral cortex (29% vs 73%, P = .026), shorter TAD (13.4 mm vs 18.5 mm, P = .042), and greater varus collapse (6.2 degrees vs 1.3 degrees, P \u3c .001) compared to patients with nail toggle \u3c 4 degrees. Conclusions: Lower percentage nail fill of the canal and shorter TAD are risk factors for increased nail toggle in short CMNs. Increased nail toggle is associated with increased varus collapse

The association between heterosexual anal intercourse and HIV acquisition in three prospective cohorts of women

The extent to which receptive anal intercourse (RAI) increases the HIV acquisition risk of women compared to receptive vaginal intercourse (RVI) is poorly understood. We evaluated RAI practice over time and its association with HIV incidence during three prospective HIV cohorts of women: RV217, MTN-003 (VOICE), and HVTN 907. At baseline, 16% (RV 217), 18% (VOICE) of women reported RAI in the past 3 months and 27% (HVTN 907) in the past 6 months, with RAI declining during follow-up by around 3-fold. HIV incidence in the three cohorts was positively associated with reporting RAI at baseline, albeit not always significantly. The adjusted hazard rate ratios for potential confounders (aHR) were 1.1 (95% Confidence interval: 0.8-1.5) for VOICE and 3.3 (1.6-6.8) for RV 217, whereas the ratio of cumulative HIV incidence by RAI practice was 1.9 (0.6-6.0) for HVTN 907. For VOICE, the estimated magnitude of association increased slightly when using a time-varying RAI exposure definition (aHR = 1.2; 0.9-1.6), and for women reporting RAI at every follow-up survey (aHR = 2.0 (1.3-3.1)), though not for women reporting higher RAI frequency (> 30% acts being RAI vs. no RAI in the past 3 months; aHR = 0.7 (0.4-1.1)). Findings indicated precise estimation of the RAI/HIV association, following multiple RVI/RAI exposures, is sensitive to RAI exposure definition, which remain imperfectly measured. Information on RAI practices, RAI/RVI frequency, and condom use should be more systematically and precisely recorded and reported in studies looking at sexual behaviors and HIV seroconversions; standardized measures would aid comparability across geographies and over time

Определение профиля флавоноидов в гипогликемическом сборе методом высокоэффективной жидкостной хроматографии

Objectives. Herbal hypoglycemic drugs complement the conventional approach to the treatment of type-2 diabetes based on the use of synthetic prescription drugs. However, their scientifically based application and standardization are limited due to inadequate and often outdated information on their chemical composition. Accordingly, we have developed a hypoglycemic collection (HGС) consisting of common bean pods (Phaseolus vulgaris L.), bilberry shoots (Vaccinium myrtillus L.), galega herb (Gallega officinalis L.), common knotgrass herb (Polygonum aviculare L.), burdock roots (Arctium lappa L.), and cinnamon rose hips (Rosa cinnamomea L.). According to a number of researchers, the antidiabetic properties of these herbs are largely due to the presence of polyphenolic compounds, especially flavonoids. The aim of this study was to determine the profile of flavonoids in the HGС and in its total dry extract (TDE).Methods. The study was performed by reverse-phase high-performance liquid chromatography with diode array and mass spectrometric detection.Results. Nine individual flavonol glycosides—derivatives of myricetin, quercetin, kaempferol and kaempferide—were identified in the HGC and the TDE. The main flavonol glycosides in the studied objects were robinin and kaempferol-3-glucuronide, the contents of which in the HGC were 2.09 and 2.22 mg/g, in the TDE 4.85 and 3.84 mg/g, respectively. The other flavonol glycosides were determined in the HGC and its TDE at significantly lower concentrations.Conclusions. The method developed in the study can be used to standardize HGCs and estimate their pharmacological activities.Цели. Гипогликемические препараты растительного происхождения успешно дополняют синтетические рецептурные лекарства, использующиеся в традиционном подходе к лечению сахарного диабета 2 типа. Однако научно обоснованное применение и стандартизация таких препаратов ограничены из-за неадекватной и часто устаревшей информации об их химическом составе. Нами был разработан гипогликемический сбор (ГГС), состоящий из створок фасоли обыкновенной (Phaseolus vulgaris L.), побегов черники обыкновенной (Vaccinium myrtillus L.), травы галеги лекарственной (Gallega officinalis L.), травы горца птичьего (спорыша) (Polygonum aviculare L.), корней лопуха большого (Arctium lappa L.), плодов шиповника коричного (Rosa cinnamomea L.). По мнению ряда исследователей, антидиабетические свойства вышеупомянутых растений во многом обусловлены присутствием в них полифенольных соединений, особенно флавоноидов. Цель данного исследования – определение профиля флавоноидов в ГГС и в суммарном сухом экстракте (ССЭ) на основе ГГС.Методы. Исследование проводили методом обращено-фазовой высокоэффективной жидкостной хроматографии с диодно-матричным и масс-спектрометрическим детектированием.Результаты. В ГГС и ССЭ было идентифицировано девять индивидуальных флавонолгликозидов – производных мирицетина, кверцетина, кемпферола и кемпферида. Основными флавонолгликозидами в исследуемых объектах были робинин и кемпферол-3-глюкуронид, содержание которых в ГГС составило 2.09 и 2.22 мг/г, в ССЭ – 4.85 и 3.84 мг/г, соответственно. Остальные флавонолгликозиды были обнаружены в ГГС и ССЭ в существенно более низких концентрациях.Выводы. Результаты работы могут быть использованы при стандартизации ГГС и оценке его фармакологической активности