Pollinator attraction of Vitis vinifera subsp. silvestris

The pollen from the morphologically hermaphrodite flowers of wild grape is sterile. Subsequently, Vitis vinifera L. subsp. silvestris (C. C. GMELIN) HEGI is functionally  dioecious. The sterile pollen of these wild-growing plants is the only food source for many insects. While the presence of visually conspicious anthers is necessary in order to attract Halictidae and Syrphidae, they do not appear to have a signal function for beetles. Beetles arrive at the flowers by scent orientation. There are structures in the flowers, called "nectaries", which do not produce nectar and are, in actual fact, odour glands. These structures may be derived from the true nectary.Die Anlockung blütenbesuchender Insekten durch Vitis vinifera subspec. silvestrisDer Pollen der morphologisch hermaphroditen Blüten der Wildrebe Vitis vinifera L. subspec. silvestris (C. C. GMELIN) HEGI ist steril; die Art muß daher als funktionell diözisch betrachtet werden. Der (sterile) Pollen ist für die Insekten die einzige „Belohnung". Die optisch auffälligen Antheren sind eine notwendige Voraussetzung für die Attraktion der Halictiden (Schmal- oder Furchenbienen) und Syrphiden (Schweb- oder Schwirrfliegen); für Käfer haben sie jedoch keine Signalfunktion. Käfer werden durch Duftorientierung zu den Blüten hingeführt. In den Blüten finden sich Strukturen, die "Nektarien" genannt werden, jedoch keinen Nektar produzieren. Es handelt sich dabei um Duftdrüsen. Es ist anzunehmen, daß die Duftdrüsen abgewandelte Nektarien sind, die eine neue Funktion angenommen haben

WNT signaling : activation, repression and fine-tuning of TCF transcription factors

In the absence of a Wnt signal ß-catenin is phosphorylated by GSK3-ß, in a complex also containing Axin and APC. Upon phosphorylation, ß-catenin is primed for ubiquitination and subsequent degradation by the proteasome. In the nucleus, Tcf proteins bind Groucho family members and repress target genes. When a Wnt protein reaches the cell, it associates with the transmembrane receptors Frizzled and LRP. The destruction complex of GSK3-?, APC and Axin is subsequently inactivated via Dishevelled, resulting in the accumulation of ß-catenin and its translocation to the nucleus. Here, ß-catenin associates with transcription factors of the TCF family to generate a functional transcription factor complex, resulting in transactivation of target genes. Deregulation of the WNT signaling pathway can have disastrous results. Mutations in this pathway are the cause of over 95% of primary colon carcinomas, mutations in APC, ß-catenin and Axin have been identified. Deregulation of ß-catenin activation is known to be implicated in a large number of other malignancies, such as melanoma, hepatocellular carcinoma, ovarian cancer, endometrial cancer and pilomatricoma. Tcf/Lef family transcription factors are the downstream effectors of the Wingless/Wnt signal transduction pathway. They activate the pathway by interaction with ß-cateninand can also repress the pathway by interaction with members of the Groucho (Grg/TLE) family of transcriptional co-repressors. We have now tested all known mammalian Groucho family members for their ability to interact specifically with individual Tcf/Lef family members. We found that redundancy in Tcf/Grg interactions appears to be the rule. Every Grg factor can interact with each TCF family member. We study the de-repressor role of Grg-5 in more detail and show that this protein in contrast to the long- repressor family members does not bind to histone deacetylase-1. In mouse there are five family members denoted Groucho-related genes: Grg-1, Grg-2, Grg-3, Grg-4 and Grg-5. Groucho repressors do not bind DNA directly, but affect transcription by binding transcription factors. A large variety of transcription factors including Hairy related genes, Runt domain proteins and TCF/LEF factors are known to use Groucho proteins to mediate repression. In an attempt to determine if there is any specificity in the interaction between Tcf and Grg proteins on the basis of their expression patterns in embryonic mouse tissues, we raised monoclonal antibodies specific to Grg-1, Grg-2, Grg-3, Grg-4 and Grg-5. Two novel components of the Wingless signaling cascade in drosophila were recently identified in Drosophila, Pygopus and Legless. Here we study the function of their mammalian homologs, hPYGOPUS-1, hPYGOPUS-2 and BCL9-1 and BCL-9.2. We show that PYGOPUS-2 and BCL-9.2 show a ubiquitous expression pattern in a panel of cell lines, whereas PYGOPUS-1 and BCL-9.1 expression is more restricted. PYGOPUS and BCL-9 together enhance WNT signaling in a TCF reporter assay, only when the cascade is activated by WNT-1, not by any of the other stimuli tested, including co-transfection of ß-catenin or dominant negative Axin. Cellular localization studies suggest a role of BCL-9 in nuclear transport of ß-catenin

An Experimentally Validated Model of the Propeller Force Accounting for Cross Influences on Multi-Rotor Aerial Systems

In this paper, we propose a model for the thrust coefficient of propellers that can take into account cross-influence between adjacent propellers. The aerodynamic interaction between propellers in multirotor aerial vehicles reduces the thrust they can produce. The influence between propellers depends on their relative positioning and orientation, which are taken into account by the proposed model. It is validated on measurements collected by a force sensor mounted on a propeller for different configurations of the adjacent propellers in a support structure. In this work, we focus on configurations with small relative orientations. Results show that the proposed model outperforms the traditional constant model in terms of thrust prediction on the data we collected, and it performs better than other models with fewer parameters, being the only one with less than 10% maximum percentage error

Modelling, Analysis, and Control of OmniMorph: an Omnidirectional Morphing Multi-rotor UAV

This paper introduces for the first time the design, modelling, and control of a novel morphing multi-rotor Unmanned Aerial Vehicle (UAV) that we call the OmniMorph. The morphing ability allows the selection of the configuration that optimizes energy consumption while ensuring the needed maneuverability for the required task. The most energy-efficient uni-directional thrust (UDT) configuration can be used, e.g., during standard point-to-point displacements. Fully-actuated (FA) and omnidirectional (OD) configurations can be instead used for full pose tracking, such as, e.g., constant attitude horizontal motions and full rotations on the spot, and for full wrench 6D interaction control and 6D disturbance rejection. Morphing is obtained using a single servomotor, allowing possible minimization of weight, costs, and maintenance complexity. The actuation properties are studied, and an optimal controller that compromises between performance and control effort is proposed and validated in realistic simulations. Preliminary tests on the prototype are presented to assess the propellers’ mutual aerodynamic interference.</p

The g-Factor of Hydrogen-Like Heavy Ions as a Test for QED

This thesis describes the design and construction of an experiment to test quantum electrodynamics (QED) in the presence of strong electromagnetic fields. The g-factor of a charged particle is a dimensionless constant. It relates the particle’s magnetic moment to its angular momentum and as such it determines the strength of the interaction between the particle and the magnetic field. In the case of an electron bound in the field of a heavy nucleus, the g-factor is predicted to great accuracy by bound-state quantum electrodynamics (BS-QED). Thus, the accurate determination of the g-factor of an ion inside a Penning trap serves as a stringent test of BS-QED. A bunch of heavy highly-charged ions are created and decelerated at the GSI-HITRAP facility. The bunch is finally captured and cooled to 4 Kelvin inside the Cooler trap. The cold ions are transported and injected into the g-factor Penning trap. Here the g-factor is determined using laser-microwave double-resonance spectroscopy. Presently, electron trapping is possible inside the Cooler trap and the trap is being prepared to trap ions

Search for electric dipole moments at storage rings

Permanent electric dipole moments (EDMs) violate parity and time reversal symmetry. Within the Standard Model (SM) they are many orders of magnitude below present experimental sensitivity. Many extensions of the SM predict much larger EDMs, which are therefore an excellent probe for the existence of "new physics". Until recently it was believed that only electrically neutral systems could be used for sensitive searches of EDMs. With the introduction of a novel experimental method, high precision for charged systems will be within reach as well. The features of this method and its possibilities are discussed.Comment: Proc. EXA2011, 6 pages; http://www.springerlink.com/content/45l35376832vhrg0

Matter-Antimatter Asymmetry - Aspects at Low Energy

The apparent dominance of matter over antimatter in our universe is an obvious and puzzling fact which cannot be adequately explained in present physical frameworks that assume matter-antimatter symmetry at the big bang. However, our present knowledge of starting conditions and of known sources of CP violation are both insufficient to explain the observed asymmetry. Therefore ongoing research on matter-antimatter differences is strongly motivated as well as attempts to identify viable new mechanisms that could create the present asymmetry. Here we concentrate on possible precision experiments at low energies towards a resolution of this puzzle.Comment: 6 pages, 1 figure; accepted for publication in Annalen der Physik (2015

Tissue-specific alternative splicing of TCF7L2

Common variants in the transcription factor 7-like 2 (TCF7L2) gene have been identified as the strongest genetic risk factors for type 2 diabetes (T2D). However, the mechanisms by which these non-coding variants increase risk for T2D are not well-established. We used 13 expression assays to survey mRNA expression of multiple TCF7L2 splicing forms in up to 380 samples from eight types of human tissue (pancreas, pancreatic islets, colon, liver, monocytes, skeletal muscle, subcutaneous adipose tissue and lymphoblastoid cell lines) and observed a tissue-specific pattern of alternative splicing. We tested whether the expression of TCF7L2 splicing forms was associated with single nucleotide polymorphisms (SNPs), rs7903146 and rs12255372, located within introns 3 and 4 of the gene and most strongly associated with T2D. Expression of two splicing forms was lower in pancreatic islets with increasing counts of T2D-associated alleles of the SNPs: a ubiquitous splicing form (P = 0.018 for rs7903146 and P = 0.020 for rs12255372) and a splicing form found in pancreatic islets, pancreas and colon but not in other tissues tested here (P = 0.009 for rs12255372 and P = 0.053 for rs7903146). Expression of this form in glucose-stimulated pancreatic islets correlated with expression of proinsulin (r2 = 0.84–0.90, P < 0.00063). In summary, we identified a tissue-specific pattern of alternative splicing of TCF7L2. After adjustment for multiple tests, no association between expression of TCF7L2 in eight types of human tissue samples and T2D-associated genetic variants remained significant. Alternative splicing of TCF7L2 in pancreatic islets warrants future studies. GenBank Accession Numbers: FJ010164–FJ010174