The success of filamentous fungi in colonizing most natural environments can be largely attributed to their ability to form an expanding interconnected network, the mycelium, or thallus, constituted by a collection of hyphal apexes in motion producing hyphae and subject to branching and fusion. In this work, we characterize the hyphal network expansion and the structure of the fungus Podospora anserina under controlled culture conditions. To this end, temporal series of pictures of the network dynamics are produced, starting from germinating ascospores and ending when the network reaches a few centimeters width, with a typical image resolution of several micrometers. The completely automated image reconstruction steps allow an easy post-processing and a quantitative analysis of the dynamics. The main features of the evolution of the hyphal network, such as the total length L of the mycelium, the number of "nodes" (or crossing points) N and the number of apexes A, can then be precisely quantified. Beyond these main features, the determination of the distribution of the intrathallus surfaces (S i ) and the statistical analysis of some local measures of N, A and L give new insights on the dynamics of expanding fungal networks. Based on these results, we now aim at developing robust and versatile discrete/continuous mathematical models to further understand the key mechanisms driving the development of the fungus thallus.Due to their paramount role in most ecosystems and in different sectors of human economy, filamentous fungi have attracted a lot of attention in the last decades. Indeed, these organisms are able to grow in complex environments, leading to their ubiquitous occurrence 1,2 . The success of filamentous fungi in colonizing most natural environments can be largely attributed to their ability to form hyphae, whose width typically ranges from 2 to 20 µm, and which are usually composed of multiple cells separated by septa 3 . At the edge of the fungal colony, apical cells explore new territories in search for food and are mainly involved in nutrient acquisition through the production of extracellular enzymes for the decomposition of organic matter, as well as through the sensing of their local environment 4 . Sub-apical cells generate new hyphae by lateral branching, thus increasing the density and surface area of the colony. In ascomycetes and basidiomycetes, the branches also mediate the hyphal fusion events, or anastomosis, that occur in the thallus and appear to be crucial for the exchange of nutrients and signals
The purpose of this investigation was to distinguish the abilities of the rectus abdominis (RA) muscle according to gender and sport training by means of neuromuscular parameters extracted from electromyography (EMG)-torque relationships. Thirty-eight healthy students, divided into 4 groups (i.e., 8 male runners, 10 female gymnasts, 12 male controls, and 8 female controls) were asked to perform 6 seconds of isometric trunk flexions at 20%, 25%, 75%, and 100% of their maximal voluntary contraction. Flexion torque and surface EMG of the RA muscle were recorded simultaneously to construct a EMG-torque relationship. Under maximal and submaximal conditions, an index of neuromuscular efficiency (NME) was determined to characterize the capacity of the RA muscle to develop a torque. At each level of contraction, the area of data scattering (ADS), reflecting torque and EMG fluctuations, was computed to express the capacity to maintain a constant target torque. Flexion torque, NME, and ADS values differed significantly between genders, but when data were related to anthropometric characteristics, no difference was observed. Although runners were not distinguished from male controls, gymnasts had higher flexion torque, higher NME, and lower ADS values than female controls had. These differences should reflect neural and muscular adaptations linked to the specificity of gymnastic training. These findings revealed different functional abilities of the RA muscle, according to gender and sport practices. The indices of neuromuscular capacities used in this study could constitute complementary tools to athletic trainers and professionals in sports medicine for evaluating and following, during sport-specific training programs, the abdominal muscle performance implied in force transfers with a lower cost and lower risks of back pain.
The formation of an ultra-thin aluminum oxide film at Fe0.85Al0.15(110) surface (A2 random alloy) has been studied by a variety of surface sensitive techniques (X-ray photoemission, low-energy electron diffraction, surface X-ray diffraction and scanning tunneling microscopy) supplemented by ab initio atomistic simulations. Since iron is not oxidized in the used conditions, the study focused on the coupling between aluminum oxidation and segregation processes. Compared to the bare surface, whose average composition (Fe0.6Al0.4) is closer to the B2-CsCl structure over a ∼ 3 nm depth, the oxidation hardly affects the subsurface segregation of aluminum. All the structural and chemical fingerprints point to an oxide film similar to that found on NiAl(110). It is a bilayer (∼ 7.5Å thick) with a composition close to Al10O13 and a large (18.8 × 10.7)Å 2 nearly rectangular unit cell; an almost perfect match between substrate periodicity and the (1 × 2) oxide supercell is found. Nevertheless, microscopy reveals the presence of anti-phase domain boundaries. Measured Al 2p and O 1s core level shifts match calculated ones; their origin and the relative contributions of initial/final state effects are discussed. The ubiquity of the present oxide on different supports asks for the origin of its stability.
Ankle sprains are among the most common sport-related injuries and can lead to chronic ankle instability. Impaired sensorimotor function of the ankle musculature is often suggested as a cause. The current study sought to assess and compare the isokinetic performance and electromyographic patterns of evertor and invertor muscles in patients with chronic ankle instability and in a control group. Twelve patients with chronic ankle instability and twelve healthy subjects were included. Isokinetic eccentric and concentric testing at various angular velocities was performed for eversion and inversion movements. The corresponding myoelectric activities of the fibularis longus and tibialis anterior muscles were quantified from surface electromyographic recordings by computing average root mean square values. Patients had lower myoelectric activity of the evertor and invertor muscles than controls did; this difference could account for the eccentric weakness associated with ankle instability. Functional strength ratios revealed a dynamic strength imbalance in unstable ankle patients and that may contribute to recurrent injury. Our findings suggest that rehabilitation programs for unstable ankle patients must be focused on the motor control of eccentric contractions of the ankle evertors and invertors, to boost these muscles’ contribution to ankle stabilization.
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