The Affine Structure of Gravitational Theories: Symplectic Groups and Geometry

We give a geometrical description of gravitational theories from the viewpoint of symmetries and affine structure. We show how gravity, considered as a gauge theory, can be consistently achieved by the nonlinear realization of the conformal-affine group in an indirect manner: due the partial isomorphism between $CA\left( 3,1\right)$ and the centrally extended $Sp\left( 8\right)$, we perform a nonlinear realization of the centrally extended (CE)$Sp\left( 8\right)$ in its semi-simple version. In particular, starting from the bundle structure of gravity, we derive the conformal-affine Lie algebra and then, by the non-linear realization, we define the coset field transformations, the Cartan forms and the inverse Higgs constraints. Finally we discuss the geometrical Lagrangians where all the information on matter fields and their interactions can be contained.Comment: 21 pages. arXiv admin note: text overlap with arXiv:0910.2881, arXiv:0705.460

"Magic" numbers in Smale's 7th problem

Smale's 7-th problem concerns N-point configurations on the 2-dim sphere which minimize the logarithmic pair-energy V_0(r) = -ln r averaged over the pairs in a configuration; here, r is the chordal distance between the points forming a pair. More generally, V_0(r) may be replaced by the standardized Riesz pair-energy V_s(r)= (r^{-s} -1)/s, which becomes - ln r in the limit s to 0, and the sphere may be replaced by other compact manifolds. This paper inquires into the concavity of the map from the integers N>1 into the minimal average standardized Riesz pair-energies v_s(N) of the N-point configurations on the 2-sphere for various real s. It is known that v_s(N) is strictly increasing for each real s, and for s<2 also bounded above, hence "overall concave." It is (easily) proved that v_{-2}(N) is even locally strictly concave, and that so is v_s(2n) for s<-2. By analyzing computer-experimental data of putatively minimal average Riesz pair-energies v_s^x(N) for s in {-1,0,1,2,3} and N in {2,...,200}, it is found that {v}_{-1}^x(N) is locally strictly concave, while v_s^x(N) is not always locally strictly concave for s in {0,1,2,3}: concavity defects occur whenever N in C^{x}_+(s) (an s-specific empirical set of integers). It is found that the empirical map C^{x}_+(s), with s in {-2,-1,0,1,2,3}, is set-theoretically increasing; moreover, the percentage of odd numbers in C^{x}_+(s), s in {0,1,2,3}, is found to increase with s. The integers in C^{x}_+(0) are few and far between, forming a curious sequence of numbers, reminiscent of the "magic numbers" in nuclear physics. It is conjectured that the "magic numbers" in Smale's 7-th problem are associated with optimally symmetric optimal-energy configurations.Comment: 109 pages, of which 30 are numerical data tables. Thoroughly revised version, to appear in J. Stat. Phys. under the different title: `Optimal N point configurations on the sphere: "Magic" numbers and Smale's 7th problem

Temporal shifts of Bois Noir phytoplasma types infecting grapevine in South Tyrol (Northern Italy)

Research Not

Phospho.ELM:a database of experimentally verified phosphorylation sites in eukaryotic proteins

BACKGROUND: Post-translational phosphorylation is one of the most common protein modifications. Phosphoserine, threonine and tyrosine residues play critical roles in the regulation of many cellular processes. The fast growing number of research reports on protein phosphorylation points to a general need for an accurate database dedicated to phosphorylation to provide easily retrievable information on phosphoproteins.DESCRIPTION: Phospho.ELM http://phospho.elm.eu.org is a new resource containing experimentally verified phosphorylation sites manually curated from the literature and is developed as part of the ELM (Eukaryotic Linear Motif) resource. Phospho.ELM constitutes the largest searchable collection of phosphorylation sites available to the research community. The Phospho.ELM entries store information about substrate proteins with the exact positions of residues known to be phosphorylated by cellular kinases. Additional annotation includes literature references, subcellular compartment, tissue distribution, and information about the signaling pathways involved as well as links to the molecular interaction database MINT. Phospho.ELM version 2.0 contains 1703 phosphorylation site instances for 556 phosphorylated proteins.CONCLUSION: Phospho.ELM will be a valuable tool both for molecular biologists working on protein phosphorylation sites and for bioinformaticians developing computational predictions on the specificity of phosphorylation reactions.</p

Infection rates of natural psyllid populations with ‘Candidatus Phytoplasma mali’ in South Tyrol (Northern Italy)

Apple proliferation is a severe disease of apple trees spreading in many European apple growing areas. It is caused by ‘Candidatus Phytoplasma mali’ that was shown to be transmitted through infected grafting material, via natural root grafts and by sap-sucking insects. Two psyllid species, Cacopsylla picta and C. melanoneura, that are recognised as the vectors of the disease, occur in orchards of South Tyrol (Northern Italy). The aim of this study was to assess the infection rates of natural populations of these insect species with ‘Ca. P. mali’. Two additional psyllid species (C. mali and Trioza urticae), which are frequent in some apple orchards of South Tyrol, were also investigated. A total of 801 specimens from 18 orchards was analysed using a real-time PCR procedure. While no specimen of T. urticae was found to be infected with ‘Ca. P. mali’, the mean infection rate of C. melanoneura and C. mali was below 1 %. The highest infection rate was found for C. picta, with a mean value of 11 % and peaking at 33%. Based on these results, it can be concluded that C. picta plays the major role as the vector of apple proliferation in South Tyrol. Keywords: apple proliferation, Cacopsylla mali, Cacopsylla melanoneura, Cacopsylla picta, pathogen transmission, Trioza urtica

Test beam Characterizations of 3D Silicon Pixel detectors

3D silicon detectors are characterized by cylindrical electrodes perpendicular to the surface and penetrating into the bulk material in contrast to standard Si detectors with planar electrodes on its top and bottom. This geometry renders them particularly interesting to be used in environments where standard silicon detectors have limitations, such as for example the radiation environment expected in an LHC upgrade. For the first time, several 3D sensors were assembled as hybrid pixel detectors using the ATLAS-pixel front-end chip and readout electronics. Devices with different electrode configurations have been characterized in a 100 GeV pion beam at the CERN SPS. Here we report results on unirradiated devices with three 3D electrodes per 50 x 400 um2 pixel area. Full charge collection is obtained already with comparatively low bias voltages around 10 V. Spatial resolution with binary readout is obtained as expected from the cell dimensions. Efficiencies of 95.9% +- 0.1 % for tracks parallel to the electrodes and of 99.9% +- 0.1 % at 15 degrees are measured. The homogeneity of the efficiency over the pixel area and charge sharing are characterized.Comment: 5 pages, 7 figure

The Effects of a High Fat Meal on Blood Flow Regulation during Arm Exercise

A diet high in saturated fats results in endothelial dysfunction and can lead to atherosclerosis, a precursor to cardiovascular disease. Exercise training is a potent stimulus though to mitigate the negative effects of a high saturated fat diet; however, it is unclear how high-saturated fat meal (HSFM) consumption impacts blood flow regulation during a single exercise session. PURPOSE: This study sought to examine the impact of a single HSFM on peripheral vascular function during an acute upper limb exercise bout. METHODS: Ten young healthy individuals completed two sessions of progressive handgrip exercise. Subjects either consumed a HSFM (0.84 g of fat/kg of body weight) 4 hours prior or remained fasted before the exercise bout. Progressive rhythmic handgrip exercise (6kg, 12kg, 18kg) was performed for 3 minutes per stage at rate of 1 Hz. The brachial artery (BA) diameter and blood velocity was obtained using Doppler Ultrasound (GE Logiq e) and BA blood flow was calculated with these values. RESULTS: BA blood flow and flow mediated dilation (normalized for shear rate) during the handgrip exercise significant increased from baseline in all workloads, but no differences were revealed in response to the HSFM consumption. CONCLUSION: Progressive handgrip exercise augmented BA blood flow and flow mediated dilation in both testing days; however, there was no significant differences following the HSFM consumption. This suggests that upper limb blood flow regulation during exercise is unaltered by a high fat meal in young healthy individuals.https://scholarscompass.vcu.edu/gradposters/1060/thumbnail.jp

Occurrence of Stolbur phytoplasma in the vector Hyalesthes obsoletus, herbaceous host plants and grapevine in South Tyrol (Northern Italy)

Bois noir (BN) is a grapevine yellows disease caused by a phytoplasma of the Stolbur group (16SrXII-A). The planthopper Hyalesthes obsoletus is known to be the principal vector and can accidentally transmit the phytoplasma from its herbaceous host plants to grapevine (Vitis vinifera). Due to the increasing incidence of BN over the last decade, a monitoring study was conducted in South Tyrol (Northern Italy). Over a period of up to four years, 659 insect vector samples, 516 herbaceous plants of 41 potential host plant species as well as 56 grapevine samples from BN-affected vineyards were tested for the presence of the Stolbur phytoplasma using a nested PCR procedure. In addition, a recently developed TaqMan allelic discrimination assay was employed to determine different subtypes of BN in infected samples. The Stolbur phytoplasma could be detected in all three sample types analysed, and was shown to belong to two different subtypes, VK type I and VK type II. In most vineyards one subtype was found to be predominant. The average infection rate of H. obsoletus amounted to 24.1 %. Analysis of herbaceous plants revealed that 25.1 % of the Convolvulus arvensis samples tested positive for the BN phytoplasma, as well as 4.5 % of the Urtica dioica samples. Taken together, our results underline the role of these two species commonly found in the undergrowth vegetation of South Tyrolean vineyards as an important reservoir of the Stolbur phytoplasma.