Algorithmic Thomas Decomposition of Algebraic and Differential Systems

In this paper, we consider systems of algebraic and non-linear partial differential equations and inequations. We decompose these systems into so-called simple subsystems and thereby partition the set of solutions. For algebraic systems, simplicity means triangularity, square-freeness and non-vanishing initials. Differential simplicity extends algebraic simplicity with involutivity. We build upon the constructive ideas of J. M. Thomas and develop them into a new algorithm for disjoint decomposition. The given paper is a revised version of a previous paper and includes the proofs of correctness and termination of our decomposition algorithm. In addition, we illustrate the algorithm with further instructive examples and describe its Maple implementation together with an experimental comparison to some other triangular decomposition algorithms.Comment: arXiv admin note: substantial text overlap with arXiv:1008.376

Neuroendocrine control of satiation

Eating is a simple behavior with complex functions. The unconscious neuroendocrine process that stops eating and brings a meal to its end is called satiation. Energy homeostasis is mediated accomplished through the control of meal size via satiation. It involves neural integrations of phasic negative-feedback signals related to ingested food and tonic signals, such as those related to adipose tissue mass. Energy homeostasis is accomplished through adjustments in meal size brought about by changes in these satiation signals. The best understood meal-derived satiation signals arise from gastrointestinal nutrient sensing. Gastrointestinal hormones secreted during the meal, including cholecystokinin, glucagon-like peptide 1, and PYY, mediate most of these. Other physiological signals arise from activation of metabolic-sensing neurons, mainly in the hypothalamus and caudal brainstem. We review both classes of satiation signal and their integration in the brain, including their processing by melanocortin, neuropeptide Y/agouti-related peptide, serotonin, noradrenaline, and oxytocin neurons. Our review is not comprehensive; rather, we discuss only what we consider the best-understood mechanisms of satiation, with a special focus on normally operating physiological mechanism

Combined whole-body vibration, resistance exercise, and sustained vascular occlusion increases PGC-1α and VEGF mRNA abundances

We previously reported that high load resistance exercise with superimposed whole-body vibration and sustained vascular occlusion (vibroX) markedly improves cycling endurance capacity, increases capillary-to-fibre ratio and skeletal muscle oxidative enzyme activity in untrained young women. These findings are intriguing, since increases in oxidative muscle phenotype and endurance capacity are typically induced by endurance but not heavy resistance exercise. Here, we tested the hypothesis that vibroX activates genes associated with mitochondrial biogenesis and angiogenesis. Eight healthy, recreationally resistance-trained young men performed either vibroX or resistance exercise (RES) in a randomised, cross-over design. Needle biopsies (M. vastus lateralis) were obtained at rest and 3h post-exercise. Changes in relative gene expression levels were assessed by real-time quantitative PCR. After vibroX, vascular endothelial growth factor and peroxisome proliferator-activated receptor-γ coactivator 1α mRNA abundances increased to 2- and 4.4-fold, respectively, but did not significantly change above resting values after RES. Other genes involved in mitochondrial biogenesis were not affected by either exercise modality. While vibroX increased the expression of hexokinase II, xanthine dehydrogenase, and manganese superoxide dismutase mRNA, there were no changes in these transcripts after RES. This study demonstrates that high load resistance exercise with superimposed whole-body vibration and sustained vascular occlusion activates metabolic and angiogenic gene programs, which are usually activated after endurance but not resistance exercise. Thus, targeted modification of high load resistance exercise by vibration and vascular occlusion might represent a novel strategy to induce endurance-type muscle adaptation

CD146 expression profile in human skin and pre-vascularized dermo-epidermal skin substitutes in vivo

Background CD146 is a cell adhesion molecule whose expression profile in human skin has not yet been elucidated. Here, we characterize CD146 expression pattern in human skin, in particular in blood endothelial cells (BECs) and lymphatic endothelial cells (LECs), which constitute human dermal microvascular endothelial cells (HDMECs), as well as in perivascular cells. Results We demonstrated that CD146 is a specific marker of BECs, but not of LECs. Moreover, we found CD146 expression also in human pericytes surrounding blood capillaries in human skin. In addition, we demonstrated that CD146 expression is up-regulated by the TNFα-IL-1β/NF-kB axis in both BECs and pericytes. Finally, we engineered 3D collagen hydrogels composed of HDMECs, CD146+ pericytes, and fibroblasts which developed, in vitro and in vivo, a complete microvasculature network composed of blood and lymphatic capillaries with pericytes investing blood capillaries. Conclusions Overall, our results proved that CD146 is a specific marker of BECs and pericytes, but not LECs in human skin. Further, the combination of CD146+ pericytes with HDMECs in skin substitutes allowed to bioengineer a comprehensive 3D in vitro and in vivo model of the human dermal microvasculature

On the General Analytical Solution of the Kinematic Cosserat Equations

Based on a Lie symmetry analysis, we construct a closed form solution to the kinematic part of the (partial differential) Cosserat equations describing the mechanical behavior of elastic rods. The solution depends on two arbitrary analytical vector functions and is analytical everywhere except a certain domain of the independent variables in which one of the arbitrary vector functions satisfies a simple explicitly given algebraic relation. As our main theoretical result, in addition to the construction of the solution, we proof its generality. Based on this observation, a hybrid semi-analytical solver for highly viscous two-way coupled fluid-rod problems is developed which allows for the interactive high-fidelity simulations of flagellated microswimmers as a result of a substantial reduction of the numerical stiffness.Comment: 14 pages, 3 figure

Combined whole-body vibration, resistance exercise, and sustained vascular occlusion increases PGC-1α and VEGF mRNA abundances

We previously reported that high load resistance exercise with superimposed whole-body vibration and sustained vascular occlusion (vibroX) markedly improves cycling endurance capacity, increases capillary-to-fibre ratio and skeletal muscle oxidative enzyme activity in untrained young women. These findings are intriguing, since increases in oxidative muscle phenotype and endurance capacity are typically induced by endurance but not heavy resistance exercise. Here, we tested the hypothesis that vibroX activates genes associated with mitochondrial biogenesis and angiogenesis. Eight healthy, recreationally resistance-trained young men performed either vibroX or resistance exercise (RES) in a randomised, cross-over design. Needle biopsies (M. vastus lateralis) were obtained at rest and 3 h post-exercise. Changes in relative gene expression levels were assessed by real-time quantitative PCR. After vibroX, vascular endothelial growth factor and peroxisome proliferator-activated receptor-γ coactivator 1α mRNA abundances increased to 2- and 4.4-fold, respectively, but did not significantly change above resting values after RES. Other genes involved in mitochondrial biogenesis were not affected by either exercise modality. While vibroX increased the expression of hexokinase II, xanthine dehydrogenase, and manganese superoxide dismutase mRNA, there were no changes in these transcripts after RES. This study demonstrates that high load resistance exercise with superimposed whole-body vibration and sustained vascular occlusion activates metabolic and angiogenic gene programs, which are usually activated after endurance but not resistance exercise. Thus, targeted modification of high load resistance exercise by vibration and vascular occlusion might represent a novel strategy to induce endurance-type muscle adaptations

Fuelling in front of the barrier—are there age based behavioral differences in Garden Warblers Sylvia borin?

Garden Warblers Sylvia borin were studied during autumn stopover in Crete before crossing the barrier of the Mediterranean Sea and the Sahara Desert. Birds followed with transmitters show extensive stopover periods, which were longer in first-year birds, 16 days, compared with adult birds, 14 days. The distribution of body masses from birds trapped in fig trees were used to estimate the departure body mass and the results found indicate that both age categories on average depart with a fuel load close to 100% of lean body mass. The movement of transmitter birds shows differences between first-year and adult birds. Adult birds move further away from the release site and many also left the study area. Several were found settled outside the study area, up to 17 km away, indicating that they regularly make longer stopover movements. It is suggested that this might be a result of that they return to a place where they stayed during an earlier migration. It was shown that stopover site fidelity exists and nine garden warblers were recaptured in the area during a following autumn. The results found highlights the importance of stopover areas close to the Sahara Desert