13,508 research outputs found
Cosmic Ray Muons Timing in the ATLAS Detector
In this talk I discuss the use of calorimeter timing both for detector
commissioning and in searches for new physics. In particular I present real and
simulated cosmic ray muons data results for the ATLAS Tile Calorimeter system.
The analysis shows that several detector errors such as imperfect calibrations
can be uncovered. I also demonstrate the use of ATLAS Tile Calorimeters
excellent timing resolution in suppressing cosmic ray fake missing transverse
energy in searches for supersymmetry.Comment: Proceedings of CIPANP 2009, peer-reviewed by the ATLAS Collaboratio
Intensifying the use of benefit sanctions: an effective tool to shorten welfare receipt and speed up transitions to employment?
Benefit sanctions imposed on non-compliant welfare recipients are a new element in the German welfare system. In practice, the sanction policy and the application of sanctions vary considerably across the 439 welfare agencies. Based on combined administrative and survey data, these differences are used as instrumental variables to estimate the effect of sanctions on the drop-out from welfare and the transition to employment. The estimated local average treatment effect (LATE) is an estimate of the effctiveness of an intensified use of sanctions. The results show that tightening sanction policy would be quite effective. --benefit sanctions,welfare recipients,IV,LATE
DETERMINANTS OF ARGENTINEAN WINE PRICES IN THE U.S. MARKET
A hedonic price function for Argentinean wines in the U.S market is estimated in order to evaluate the effect of the most important attributes of wine on price. Results show that labeling practices and the choice of the right wine quality attributes are far more influential on price than expert panel opinions or oenological wine improvements such as aging.wine prices, Argentinean wine, hedonic price model, Demand and Price Analysis,
Genetic and molecular analysis of aerial plant architecture in tomato
Aerial architecture of seed plants is determined by the development of repeating modules named phytomers. An important factor therein is the formation and fate of axillary meristems (AMs), influencing agronomically important traits, like inflorescence architecture and shoot branching. The present study in tomato represents a reverse genetics approach unveiling the function of genes homologous to the MYB and bHLH proteins, Blind and LAX, two key regulators of axillary meristem initiation.
Public databases and PCR technology enabled the identification of three closely related paralogs of Blind, Blind-like1 (Bli1), Bli2 and Bli3. TILLING of Bli2 led to the identification of the classical tomato mutant potato leaf (c), a mutant described already more than a hundred years ago. potato leaf mutants display leaves with reduced leaflet formation and lack leaf lobing and serration. Nine potato leaf alleles were identified, all carrying a mutation in the Bli2 gene. RNA in-situ hybridisation revealed a distinct expression pattern in leaf primordia prior to leaflet formation, at positions axillary of outgrowing leaflets and marking the sinuses of leaf lobes. Ectopic expression of Blind (Bl) partially complemented the defects of c, indicating a conserved function of the two proteins. Silencing of Bli3 revealed that this gene probably acts in the same process as C, because RNAi plants displayed reduced leaf complexity. The protein similarity of Bl and C, the partial complementation of c by Bl and the phenotype of Bli3 RNAi plants represent further elements in the rising evidence that leaf dissection and AM initiation employ homologous mechanisms.
Furthermore, silencing of Bli1 and Bli3 unveiled that these genes redundantly regulate AM initiation in vegetative and reproductive development. The defect in AM initiation along the shoot axis was complementary to the defect of blind mutants. RNA in-situ hybridisation showed major expression domains of Blind in the shoot apical meristem, at positions of presumptive leaf primordium formation and adaxially of leaf primordia. Additionally, Blind mRNA accumulated adaxially of new reproductive and vegetative meristems. Besides AM initiation, Bl, Bli1 and Bli3 act in the prevention of concaulescent fusions of vegetative and reproductive side-shoots. Moreover, a series of observations disclosed that Bl, Bli1 and Bli3 control the maintenance and reproductive identity of apical and axillary meristems.
In a second project, silencing of the bHLH transcription factor SlLax in tomato, led to the identification of the classical mutant, uniflora. SlLax/Uniflora encodes an ortholog of the AM initiation regulators, LAX (rice), ba1 (maize) and ROB (Arabidopsis). Uniflora (Uf) was known to control inflorescence architecture and flowering time in a condition dependent manner. Detailed analysis of organogenesis in different uniflora mutant lines, unveiled that Uf controls the initiation of reproductive axillary meristems and regulates reproductive meristem identity. RNA in-situ hybridisation indicated that Uf mRNA accumulates adaxially of newly initiated reproductive AMs, similar to the expression pattern of Blind in inflorescences. Heterodimers of bHLH and MYB proteins regulate several developmental processes. Previous studies showed that the Uf and Blind orthologous proteins ROB and RAX of Arabidopsis interact physically. The phenotypic similarities of Uf and Bl, Bli1 and Bli3 loss of function plants, and the overlapping expression patterns of Uf and Bl strongly suggest that also in tomato these MYB and bHLH proteins may act as heterodimers controlling AM initiation and meristem identity in reproductive development. Together, the observations in tomato, rice, maize and Arabidopsis propose that heterodimers of Blind and LAX orthologous MYB and bHLH proteins constitute a fundamental mechanism, controlling axillary meristem formation in flowering plants.
In summary, the present study unveiled the identity of two classical mutants and demonstrated that genes of the Blind family and Uniflora regulate four important features of aerial plant architecture in tomato: leaf compoundness, organ separation, axillary meristem initiation and the development of apical meristems
Design and Validation of a Variable Stiffness Three Degree of Freedom Planar Robot Arm
The need exists for robotic manipulators that can interact with an environment having uncertain kinematic constraints. A robot has been designed and built for proof of concept of a passive variable compliance control strategy that can vary joint stiffness to achieve higher performance dexterous manipulation. This novel planar robot incorporating variable stiffness actuators and common industrial controls allows the robot to comply with its environment when needed but also have high stiffness for precise motion control in free space. To perform both functions well, a high stiffness ratio (max/min stiffness) is required. A stiffness ratio up to 492 was achieved. The robot performance was evaluated with the task of turning a crank to lift a weight despite nominal positioning inaccuracy. The novel variable stiffness robot was able to complete the task faster and with lower constraint forces than a traditional force-controlled stiff robot. The time to complete the task using passive variable stiffness control was twenty-nine times faster with constraint forces less than one fifth those achieved using traditional active compliance control
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