How an antenna launches its input power into radiation: the pattern of the Poynting vector at and near an antenna

In this paper I first address the question of whether the seat of the power radiated by an antenna made of conducting members is distributed over the ``arms'' of the antenna according to -J . E, where J is the specified current density and E is the electric field produced by that source. Poynting's theorem permits only a global identification of the total input power, usually from a localized generator, with the total power radiated to infinity, not a local correspondence of -J . E dv with some specific radiated power, r^2 S . n dO. I then describe a model antenna consisting of two perfectly conducting hemispheres of radius a separated by a small equatorial gap across which occurs the driving oscillatory electric field. The fields and surface current are determined by solution of the boundary value problem. In contrast to the first approach (not a boundary value problem), the tangential electric field vanishes on the metallic surface. There is no radial Poynting vector normal to the surface. Numerical examples are shown to illustrate how the energy flows from the input region of the gap and is guided near the antenna by its ``arms'' until it is launched at larger r/a into the radiation pattern determined by the value of ka.Comment: 24pages, 8 figures, submitted for publicatio

Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men

We analysed the importance of systemic and peripheral arteriovenous O2 difference (a- v− O2 and a-vf O2 difference, respectively) and O2 extraction fraction for maximal oxygen uptake ( V˙ O2max ). Fick law of diffusion and the Piiper and Scheid model were applied to investigate whether diffusion vs perfusion limitations vary with V˙ O2max . Articles (n=17) publishing individual data (n=154) on V˙ O2max , maximal cardiac output ( Q˙ max ; indicator-dilution or Fick method), a- v− O2 difference (catheters or Fick equation) and systemic O2 extraction fraction were identified. For the peripheral responses, group-mean data (articles: n=27; subjects: n=234) on leg blood flow (LBF; thermodilution), a-vf O2 difference and O2 extraction fraction (arterial and femoral venous catheters) were obtained. Q˙ max and two-LBF increased linearly by 4.9-6.0 L·min-1 per 1 L·min-1 increase in V˙ O2max (R2 =0.73 and R2 =0.67, respectively; both P<0.001). The a- v− O2 difference increased from 118-168 mL·L-1 from a V˙ O2max of 2-4.5 L·min-1 followed by a reduction (second-order polynomial: R2 =0.27). After accounting for a hypoxemia-induced decrease in arterial O2 content with increasing V˙ O2max (R2 =0.17; P<0.001), systemic O2 extraction fraction increased up to ~90% ( V˙ O2max : 4.5 L·min-1 ) with no further change (exponential decay model: R2 =0.42). Likewise, leg O2 extraction fraction increased with V˙ O2max to approach a maximal value of ~90-95% (R2 =0.83). Muscle O2 diffusing capacity and the equilibration index Y increased linearly with V˙ O2max (R2 =0.77 and R2 =0.31, respectively; both P<0.01), reflecting decreasing O2 diffusional limitations and accentuating O2 delivery limitations. In conclusion, although O2 delivery is the main limiting factor to V˙ O2max , enhanced O2 extraction fraction (≥90%) contributes to the remarkably high V˙ O2max in endurance-trained individuals

Circulating Brain-Injury Markers After Surgery for Craniosynostosis

Objective: Historically, there have been few quantitative methods for effectively evaluating outcomes after surgery for craniosynostosis. In this prospective study, we assessed a novel approach for detecting possible postsurgery brain injury in patients with craniosynostosis. Methods: We included consecutive patients operated on for sagittal (pi-plasty or craniotomy combined with springs) or metopic (frontal remodeling) synostosis at the Craniofacial Unit at Sahlgrenska University Hospital, Gothenburg, Sweden, from January 2019 to September 2020. Plasma concentrations of the brain-injury biomarkers neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and tau were measured immediately before induction of anesthesia, immediately before and after surgery, and on the first and the third postoperative days using single-molecule array assays. Results: Of the 74 patients included, 44 underwent craniotomy combined with springs for sagittal synostosis, 10 underwent pi-plasty for sagittal synostosis, and 20 underwent frontal remodeling for metopic synostosis. Compared with baseline, GFAP level showed a maximal significant increase at day 1 after frontal remodeling for metopic synostosis and pi-plasty (P = 0.0004 and P = 0.003, respectively). By contrast, craniotomy combined with springs for sagittal synostosis showed no increase in GFAP. For neurofilament light, we found a maximal significant increase at day 3 after surgery for all procedures, with significantly higher levels observed after frontal remodeling and pi-plasty compared with craniotomy combined with springs (P < 0.001). Conclusions: These represent the first results showing significantly increased plasma levels of brain-injury biomarkers after surgery for craniosynostosis. Furthermore, we found that more extensive cranial vault procedures resulted in higher levels of these biomarkers relative to less extensive procedures

Achieving energy balance with a high‐fat meal does not enhance skeletal muscle adaptation and impairs glycemic response in a sleep‐low training model

Training with low carbohydrate availability (LCHO) has shown to acutely enhance endurance training skeletal muscle response, but concomitant energy deficit (ED) in LCHO interventions has represented a confounding factor in past research. This study aimed at determining if achieving energy balance with high‐fat (EB‐HF) acutely enhances the adaptive response in LCHO compared to ED low‐fat (ED‐LF). In a crossover design, nine well‐trained males completed a ‘sleep‐low’ protocol: on day 1 they cycled to deplete muscle glycogen while reaching a set energy expenditure (30 kcal/kg of fat free mass (FFM)). Post‐exercise, low carbohydrate, protein‐matched meals completely (EB‐HF, 30 kcal/kg FFM) or partially (ED‐LF, 9 kcal/kg FFM) replaced the energy expended, with the majority of energy derived from fat in EB‐HF. In the morning of day 2, participants exercised fasted and skeletal muscle and blood samples were collected and a carbohydrate‐protein drink was ingested at 0.5h recovery. Muscle glycogen showed no treatment effect (P < 0.001) and decreased from 350 ±98 and 192 ±94 mmol/kg dry‐mass between rest and 0.5 h recovery. Phosphorylation status mTOR and AMPK pathway proteins showed only time effects. mRNA expression of p53 increased after exercise (P = 0.005) and was higher in ED‐LF at 3.5h compared to EB‐HF (P = 0.027). Plasma glucose and insulin AUC (P < 0.04) and peak values (P≤0.05) were higher in EB‐HF after the recovery drink. Achieving energy balance with a high‐fat meal in a ‘train‐low’ (‘sleep‐low’) model did not enhance markers of skeletal muscle adaptation and impaired glycemia in response to a recovery drink following training in the morning

Treatment of mastitis during lactation

Treatment of mastitis should be based on bacteriological diagnosis and take national and international guidelines on prudent use of antimicrobials into account. In acute mastitis, where bacteriological diagnosis is not available, treatment should be initiated based on herd data and personal experience. Rapid bacteriological diagnosis would facilitate the proper selection of the antimicrobial. Treating subclinical mastitis with antimicrobials during lactation is seldom economical, because of high treatment costs and generally poor efficacy. All mastitis treatment should be evidence-based, i.e., the efficacy of each product and treatment length should be demonstrated by scientific studies. Use of on-farm written protocols for mastitis treatment promotes a judicious use of antimicrobials and reduces the use of antimicrobials

Chuanxiongzine relaxes isolated corpus cavernosum strips and raises intracavernous pressure in rabbits

It has been shown that there are many Chinese traditional herbals that can enhance sexual activity. Chuanxiongzine is a vasoactive ingredient that has been isolated and purified from Ligusticum chuanxiong Hort. In previous studies, it has been found that chuanxiongzine was effective in relaxing rabbit corpus cavernosum smooth muscle. We determined the effects of chuanxiongzine on relaxation of isolated corpus cavernosum strips in vitro and on increase of intracavernous pressure (ICP) in vivo in rabbits. Chuanxiongzine caused a concentration-dependent relaxation of phenylephrine precontracted isolated corpus cavernosum strips (EC50 1.58 × 10−4 mol l−1), which were endothelium independent and NO independent. However, the guanylyl cyclase inhibitor 1-H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one significantly shifted the chuanxiongzine concentration–response relationship to the right. Although there was no significant difference in the level of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in isolated corpus cavernosum strips treated with chuanxiongzine or vehicle, chuanxiongzine caused a significant rise in the level of cGMP and cAMP in isolated corpus cavernosum strips pretreated with the activator of adenylyl cyclase forskolin and the source of NO sodium nitroprusside. In an in vivo study, chuanxiongzine dose-dependently raised ICP after the intracavernous injection of its cumulative doses (0.5, 1, 2 and 5 mg kg−1). The ICP increased from baseline to 19.1±3.7, 24.8±2.1, 30.2±4.8 and 39.7±6.1 mm Hg, respectively, and the duration of tumescence ranged from 8.5±2.8 to 22.9±7.3 min. Our results show that chuanxiongzine can relax isolated corpus cavernosum strips of rabbits in vitro and increase ICP of rabbits in vivo, which is neither endothelium dependent nor NO dependent, but may be partly mediated by the inhibition of cAMP phosphodiesterase or cGMP phosphodiesterase