Recursive Calculation of Effective Potential and Variational Resummation

We set up a method for a recursive calculation of the effective potential which is applied to a cubic potential with imaginary coupling. The result is resummed using variational perturbation theory (VPT), yielding an exponentially fast convergence.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html Latest update of paper (including all PS fonts) at http://www.physik.fu-berlin.de/~kleinert/350

COMPUTER SIMULATIONS OF BACK SOMERSAULTS IN PLATFORM DIVING

The purpose of this study was to simulate the flight phase of a back 3½ somersault tuck (207 C) for a female elite diver. Starting with the analysis of a real performance initial conditions as angular momentum, takeoff velocity and trunk position were fixed. A multisegmental angle-driven 3D model was used to study different knee and hip angle patterns. Hip and knee angle modifications were moderate variations of the real performance. Coming quickly into a more compact position and keeping this tight position until come-out produced an advantage up to 130° total rotation and 50°/s mean angular velocity. This advantage obtained in the first flight phases could be used to improve the come-out or to reduce strength requirements at takeoff

THREE METHODS TO DETERMINE MASS CHARACTERISTICS OF HUMAN BODY SEGMENTS

Three approaches to estimate body segment parameters (BSP) are compared, a volumescanning photographic method, a force plate technique and a geometric method. First approach: a 3D body scanner was used to obtain a closed surface mesh of a subject. Closed loops were employed to divide the mesh into head, thorax, pelvis and limbs. Volume and center of mass (CM) of each segment were computed. Second approach: a triangular reaction board with two force sensors was used to measure the position of the CM. Third approach: The multi-body simulation software dynamicus/alaska models the segments by geometric shapes like elliptic solids, ellipsoids, and semi-ellipsoids. The results indicate that the body scanner method is highly accurate and an integration into dynamicus/alaska would increase simulation accuracy

A COMPARISON OF TWO BODY SEGMENT PARAMETER MODELS VIA ANGULAR MOMENTUM AT TAKEOFF IN DIVING

The angular momentum production during the takeoff phase in diving was computed in two ways: The first approach used the Hanavan model based on 15 landmarks. The second one was an image-based individual model. The remote angular momenta of the body segments were computed and compared. It turned out that both methods yield almost the same angular momenta of the total body. Depending on the body mass the arm segments amount to 52 ± 6 % to the total angular momentum for the individual model and 57 ± 9 % for the Hanavan model. The leg contribution was 33 ± 6 % and 33 ± 7 %, the head contribution was 19.1 ± 4 % and 14.2 ± 4 % for the individual model resp. for the Hanavan model

IAP antagonization promotes inflammatory destruction of vasculature endothelium and inhibits tumor growth

The inhibitor of apoptosis (IAP) protein family encodes a group of structurally related proteins that were initially identified based on their ability to inhibit cell death. Due to their cytoprotective properties and their elevated expression levels in many types of human cancer, small molecular pharmacological inhibitors of IAPs (SMAC mimetics, SM) were developed in the last years (Kashkar, 2010; Fulda & Vucic, 2012; Bai et al, 2014). Numerous studies have focused on the role of SM-induced cell death in cancer cells. Accordingly, many SM compounds are currently in clinical trials to evaluate their potential in cancer therapy and so far, SM-mediated cell death is believed to directly target malignant cells (Fulda & Vucic, 2012; Fulda, 2014; Bai et al, 2014). In order to study the underlying mechanisms in more detail in vivo, we used a B16 melanoma mouse model with immune competent mice. The obtained results demonstrated that IAP antagonization by a pan-IAP antagonist inhibits tumor growth in vivo not by inducing direct cytotoxicity towards tumor cells. In fact, our work showed that SM triggers a TNF-dependent disruption of the vasculature in the tumor microenvironment. Specifically, SM treatment facilitated the production of TNF by B16 melanoma tumor cells, which is consistent with previous observations concerning the cellular responses to SM exposure (Wu et al, 2007). Two key components of tumor stroma, infiltrating immune cells and endothelial vasculature, were scrutinized in our study. While no significant differences in the immune cell infiltration of B16 mouse tumors were observed, we found a striking reduction of the vascularization in B16 tumors treated with SM. The lack of vascularization in B16 melanoma tumors or implanted matrigel plugs in wild type but not in TNF-R1/2-/--mice and the potentiated susceptibility of two independent EC cultures towards TNF in the presence of SM, identified the endothelial cells of the tumor vasculature as the major target of SM-induced cell death within the tumor microenvironment. Taken together, our work identified a novel anti-angiogenic activity of a pan-IAP antagonist in the presence of elevated TNF levels under inflammatory conditions within the tumor microenvironment. This could constitute an additional and perhaps complementary potential of SM, which could improve current cancer therapies

Large-D Expansion from Variational Perturbation Theory

We derive recursively the perturbation series for the ground-state energy of the D-dimensional anharmonic oscillator and resum it using variational perturbation theory (VPT). From the exponentially fast converging approximants, we extract the coefficients of the large-D expansion to higher orders. The calculation effort is much smaller than in the standard field-theoretic approach based on the Hubbard-Stratonovich transformation.Comment: Author Information under http://hbar.wustl.edu/~sbrandt and http://www.theo-phys.uni-essen.de/tp/ags/pelster_di

RESULTS OF INVERSE DYNAMICS CALCULATIONS IN JAVELIN THROWING ARE STRONGLY INFLUENCED BY INDIVIDUAL BODY SEGMENT PROPERTIES

The calculation of inverse dynamics (ID) solutions is widely used to examine potential injury risks and sources for performance enhancement. The results of these calculations are influenced, among others, by the chosen set of body segment inertia parameters (BSIP). While throwing movements are frequently analyzed via ID and there exists a broad variety of BSIP models, the influence of the BSIP sets on the outcome is not well examined. Therefore, the aim of this study was to clarify the influence of different BSIP sets on the modelling results in javelin throwing. For this purpose the kinematics of ten male javelin throwers were recorded. Six available models were used to estimate the BSIP values of the upper limp for each thrower. The chosen BSIP model had large influence on the derived BSIP parameters which showed variations between 8% and 120%. Also, the maximum net joint moment varied between 6% and 21%. Hence, our study suggests that for modelling joint kinetics in throwing movements the model should be chosen carefully

Asp-193 and Glu-218 of subunit II are involved in the Mn2+-binding of Paracoccus denitrificans cytochrome c oxidase

AbstractCytochrome c oxidase contains a binding site for a non-redox-active metal at the interface of subunits I and II, usually a magnesium ion. In Paracoccus denitrificans oxidase, typically 20% may be replaced by manganese, using standard growth media. Site-directed mutants were constructed in subunit II (D193N and E218Q), and the isolated enzymes analyzed by total-reflection X-ray fluorescence spectrometry and EPR. Both mutants show a strong reduction of the manganese stoichiometry and a diminished electron transfer activity, demonstrating that D193 and E218 are involved in the binding of a manganese/magnesium ion in this site

Infection of cells with replication deficient adenovirus induces cell cycle alterations and leads to downregulation of E2F-1

AbstractGene products of recombinant replication-deficient adenovirus vectors of the first generation (Ad vector) can induce cell cycle dysregulation and apoptosis after infection in eukaryotic cells. The mechanisms underlying this complex process are largely unknown. Therefore, we investigated the regulation of the pRb/E2F-1 complex, which controls transition from G0/G1 to S phase of the cell cycle. As Ad vector infection results in a decrease in the number of cells in G0/G1 phase of the cell cycle, we observed a decline of the pRb protein level and, surprisingly, also a decrease of the E2F-1 protein and mRNA level in infected cell lines. Furthermore, in contrast to the reduction of cells in the G0/G1 phase we observed increased protein levels of p53 and p21 proteins. However, as experiments in p53 deficient cell lines indicated, the decrease of pRb and E2F-1 is independent of p53 and p21 expression. Moreover, results obtained with Rb deficient cell lines indicated that the reduced E2F-1 expression is independent of pRb. These results suggest that Ad vector-induced cell cycle dysregulation is associated with a specific downregulation of E2F-1 independent of Rb and p53 genomic status of cells

Plasticity-Related Gene 5 Is Expressed in a Late Phase of Neurodifferentiation After Neuronal Cell-Fate Determination

During adult neurogenesis, neuronal stem cells differentiate into mature neurons that are functionally integrated into the existing network. One hallmark during the late phase of this neurodifferentiation process is the formation of dendritic spines. These morphological specialized structures form the basis of most excitatory synapses in the brain, and are essential for neuronal communication. Additionally, dendritic spines are affected in neurological disorders, such as Alzheimer's disease or schizophrenia. However, the mechanisms underlying spinogenesis, as well as spine pathologies, are poorly understood. Plasticity-related Gene 5 (PRG5), a neuronal transmembrane protein, has previously been linked to spinogenesis in vitro. Here, we analyze endogenous expression of the PRG5 protein in different mouse brain areas, as well as on a subcellular level. We found that native PRG5 is expressed dendritically, and in high abundance in areas characterized by their regenerative capacity, such as the hippocampus and the olfactory bulb. During adult neurogenesis, PRG5 is specifically expressed in a late phase after neuronal cell-fate determination associated with dendritic spine formation. On a subcellular level, we found PRG5 not to be localized at the postsynaptic density, but at the base of the synapse. In addition, we showed that PRG5-induced formation of membrane protrusions is independent from neuronal activity, supporting a possible role in the morphology and stabilization of spines