Photofocusing: Light and flow of phototactic microswimmer suspension

We explore in this paper the phenomenon of photofocusing: a coupling between flow vorticity and biased swimming of microalgae toward a light source that produces a focusing of the microswimmer suspension. We combine experiments that investigate the stationary state of this phenomenon as well as the transition regime with analytical and numerical modeling. We show that the experimentally observed scalings on the width of the focalized region and the establishment length as a function of the flow velocity are well described by a simple theoretical model

Hole growth dynamics in a two dimensional Leidenfrost droplet

International audienceWe studied the behaviors of Leidenfrost droplets confined in a Hele-Shaw cell. These droplets are unstable above a critical size and a hole grows at their center. We experimentally investigate two different systems for which the hole growth dynamics exhibits peculiar features that are driven by capillarity and inertia. We report a first regime characterized by the liquid reorganization from a liquid sheet to a liquid torus with similarities to the burst of micron-thick soap films. In the second regime the liquid torus expands and thins before fragmentation. Finally we propose models to account for the experimental results

Nucleosynthetic osmium isotope anomalies in acid leachates of the Murchison meteorite

We present osmium isotopic results obtained by sequential leaching of the Murchison meteorite, which reveal the existence of very large internal anomalies of nucleosynthetic origin. The Os isotopic anomalies are correlated, and can be explained by the variable contributions of components derived from the s, r and p-processes of nucleosynthesis. Much of the s-process rich osmium is released by relatively mild leaching, suggesting the existence of an easily leachable s-process rich presolar phase, or alternatively, of a chemically resistant r-process rich phase. The s-process composition of Os released by mild leaching diverges slightly from that released by aggressive digestion techniques, perhaps suggesting that the presolar phases attacked by these differing procedures condensed in different stellar environments. The correlation between 190Os and 188Os can be used to constrain the s-process 190Os/188Os ratio to be 1.275 pm 0.043. Such a ratio can be reproduced in a nuclear reaction network for a MACS value for 190Os of ~200 pm 22 mbarn at 30 keV. We also present evidence for extensive internal variation of 184Os abundances in the Murchison meteorite. This suggests that p process rich presolar grains (e.g., supernova condensates) may be present in meteorites in sufficient quantities to influence the Os isotopic compositions of the leachates.Comment: 40 pages, 9 figures, 2 tables. Accepted for publication in Earth and Planetary Science Letter

Motor learning in golf—a systematic review

Golf is a sport that consists of complex movement skills that need to be executed with utmost precision. Consequently, motor skill learning plays a crucial role in golf, and large numbers of studies address various methods of motor learning. In the present review, we give a systematic overview of randomized controlled trials (RCTs) on motor learning of golf-specific motor skills. Three electronic databases were searched for RCTs looking at the effect of at least one learning method on performance in a golf-specific motor task. We grouped the studies depending on the learning strategies “cognitive training”, “practice scheduling”, “augmented feedback”, “implicit and explicit learning” and “focus of attention”. Fifty-two RCTs met the eligibility criteria and were included in the systematic review. Superior methods within their respective strategies were an external focus of attention and increasing contextual interference, as well as errorless learning. For “cognitive training” and “augmented feedback”, no single method can be considered the most favorable. The overall biggest limitations were the lack of statistical power for more than half of the RCTs, and the fact that most studies of the present review investigated simple putting tasks in novices only. Although we have shown superiority of specific learning methods, transferability of the recommendations that can be derived from simple golf tasks in novices to sport-specific tasks in advanced players still has to be demonstrated and require study designs with the intention to provide practical recommendations for coaches and athletes in the sport of golf

AI-BASED MARKERLESS SINGLE-CAMERA MOTION ANALYSIS FOR ESTIMATING KNEE AND HIP JOINT KINEMATICS DURING GAIT

This study aimed to pilot-test a markerless motion analysis approach (i.e., SMARTGAIT) for estimating knee and hip joint kinematics in the sagittal and frontal plane during overground walking. One person (age 24 years) walked four times over an 8-meter distance. Joint kinematics were measured using SMARTGAIT (single RGB smartphone camera) and Vicon (reference system). Angle trajectories of sixteen gait cycles were used for the analysis. Agreement between SMARTGAIT and Vicon angle trajectories was greater in the sagittal plane (hip: Pearson’s r=0.989; knee: r=0.990; root mean square error [RMSE] ≤2.6 deg) compared to the frontal plane (hip: r=0.789; knee: r=0.793; RMSE ≤3.9 deg). These initial results show the potential of SMARTGAIT for measuring lower extremity joint kinematics. The camera perspective may influence the accuracy of SMARTGAIT

Preliminary results of in vitro culture of pea and lupin embryos for the reduction of generation cycles in single seed descent technique

The aim of the studies was to establish in vitro conditions for the culture of pea and lupin embryos as the first step in the development of an in vitro assisted single seed descent technique for the attainment of homozygous populations. Materials for the study included of pea, and narrow-leafed and yellow lupin cultivars. Embryos dissected from mature but still-green seeds were cultured in vitro on two modified MS media and under three temperature regimes. Shoot and root lengths of regenerated plants were measured after 7, 14 and 21 days of culture. For pea plants full-strength MS medium with 4 g l−1 agar and temperature 22/ 20°C (day/night) appeared to be the most conducive to shoot and root development, whereas for lupin plants lower temperatures were more propitious: 12°C in the dark for narrow-leafed lupin and 16/ 12°C (day/night) for yellow lupin. Almost all the cultured embryos developed into plants, but not all the regenerated plants survived acclimation to ex vitro conditions

Effects of jump training on power, strength, balance and aerobic performance in non exercising young adults

Physical inactivity is a major risk factor for noncommunicable diseases and associated mortality worldwide. A specifically tailored jump training has proven to be an efficient exercise countermeasure that can maintain health resources despite two months of otherwise complete inactivity. In the present study, we tested the effects of such a training program under real-life conditions. Seventy-five young adults (38 female, age 23 ± 3 years) were randomly assigned to either a training or a control group. The training group underwent an 8 week jump training with 15 min of jump exercises, 3 days per week. Before and after the 8-week period as well as another 8 weeks later we tested jump performance in countermovement jumps (CMJ) and hops, balance performance during one leg stance, maximal isometric strength of leg extensor muscles, stair climb performance, gait analysis, and peak oxygen uptake in a cardiopulmonary exercise test. We observed training specific increases (8 ± 9 %) in CMJ height that were explained by an optimized movement technique during the jump. We did not observe any generic improvements of anaerobic or aerobic power, strength or balance performance after the training. Solely for peak oxygen uptake, participants exhibiting low baseline levels appeared to benefit from the jump training. As the effectiveness of such training on several physiological systems had been demonstrated previously during bed rest, it is reasonable to hypothesise that the training load employed in the present study was sub-threshold for more generic adaptations in non-exercised but otherwise active participants

The case of giant lipoma of the neck

Tłuszczak jest najczęstszym nowotworem łagodnym tkanki podskórnej, wywodzącym się z dojrzałej tkanki tłuszczowej. Jest to guz zazwyczaj pojedynczy, palpacyjnie miękki, dobrze odgraniczony torebką od otoczenia, pokryty niezmienioną skórą. Rośnie wolno i bezboleśnie, osiągając najczęściej rozmiary od kilku do kilkunastu centymetrów. Leczenie polega na radykalnym, chirurgicznym wycięciu zmiany. Opisano przypadek 60-letniej kobiety z olbrzymim guzem szyi przyjętej do Oddziału Laryngologii Wojewódzkiego Szpitala Specjalistycznego nr 4 w Bytomiu celem leczenia operacyjnego. Na szczególne podkreślenie zasługuje naszym zdaniem fakt, iż osoba mieszkająca w XXI wieku w ponad 100-tysięcznym mieście, z nieograniczonym dostępem do lekarza rodzinnego, pomimo znacznego defektu kosmetycznego i uciążliwości związanej z masą guza, obejmującego tak istotną i widoczną okolicę, przez wiele lat nie decydowała się na diagnostykę i leczenie. Najprawdopodobniej strach przed interwencją chirurgiczną był zasadniczą przyczyną odkładania leczenia, gdyż według obiegowych opinii docierających do chorej zabieg operacyjny mógł spowodować zezłośliwienie guza.Lipomas, the most common lipomatous tumors and the most common benign tumors are often located in the subcutaneous tissues of limbs, back and region of head and neck but can occur in any part of human body. Those tumors are characterized by slow, painless growth. Lipomas are soft at palpation and very well encapsulated. The diagnostic processis based on clinical course, radiological visualization and biopsy. The treatment is always surgical. New methods are recommended in order to improve cosmetic effect of surgical intervention such as liposuction in addition to surgical removal for huge lipomas especially in head and neck region. It involves very small incision, liposuction of lipoma and surgical removal of the lipoma’s capsule. Similar idea is conducted by injection of steroids that leads to atrophy of the lipomatous tissue. Other substance that can be injected into lipoma before surgery is phosphatidylocholine. Recurrence is very uncommon and caused by incompleted removal. The case of the 60 year old female patient with giant tumor of the neck was shown in this paper. She neglected earlier treatment despite of very unaesthetic aspect. She was admitted to the ENT Depar tment with 11 x 16 cm diameter of tumor inorder to surgical treatment. The computer tomography visualized huge tumor of the neck. The tumor of 500 g in weigh was completely removed and plastic surgery was performed. The diagnose of lipoma was confirmed by pathologist. The epidemiology, clinical course, diagnostic and therapy were described

Preliminary results of in vitro culture of pea and lupin embryos for the reduction of generation cycles in single seed descent technique

The aim of the studies was to establish in vitro conditions for the culture of pea and lupin embryos as the first step in the development of an in vitro assisted single seed descent technique for the attainment of homozygous populations. Materials for the study included of pea, and narrow-leafed and yellow lupin cultivars. Embryos dissected from mature but still-green seeds were cultured in vitro on two modified MS media and under three temperature regimes. Shoot and root lengths of regenerated plants were measured after 7, 14 and 21 days of culture. For pea plants full-strength MS medium with 4 g l−1 agar and temperature 22/ 20°C (day/night) appeared to be the most conducive to shoot and root development, whereas for lupin plants lower temperatures were more propitious: 12°C in the dark for narrow-leafed lupin and 16/ 12°C (day/night) for yellow lupin. Almost all the cultured embryos developed into plants, but not all the regenerated plants survived acclimation to ex vitro conditions