Resonance Contributions to η\eta Photoproduction on Protons Found Using Dispersion Relations and an Isobar Model

The contributions of the resonances $D_{13}(1520)$, $S_{11}(1535)$, $S_{11}(1650)$, $D_{15}(1675)$, $F_{15}(1680)$, $D_{13}(1700)$, $P_{11}(1710)$, $P_{13}(1720)$ to $\gamma p\to \eta p$ are found from the data on cross sections, beam and target asymmetries using two approaches: fixed-t dispersion relations and an isobar model. Utilization of the two approaches and comparison of the results obtained with different parametrizations of the resonance contributions allowed us to make conclusions about the model-dependence of these contributions. We conclude that the results for the contributions of the resonances $D_{13}(1520)$, $S_{11}(1535)$, $F_{15}(1680)$ to corresponding multipole amplitudes are stable. With this the results for $D_{13}(1520)$ and $F_{15}(1680)$, combined with their PDG photoexcitation helicity amplitudes, allowed us to find the branching ratios $Br (D_{13}(1520)\to \eta N)=0.05\pm 0.02$, $Br (F_{15}(1680)\to \eta N)=0.16\pm0.04$ which have significantly better accuracy than the PDG data. The total Breit-Wigner width of the $S_{11}(1535)$ is model-dependent, we have obtained $\Gamma (S_{11}(1520))=142 MeV$ and $195 MeV$ using dispersion relations and the isobar model, respectively. The results for the $S_{11}(1650)$, $D_{15}(1675)$, $P_{11}(1710)$, $P_{13}(1720)$ are model dependent, only the signs and orders of magnitude of their contributions to multipole amplitudes are determined. The results for the $D_{13}(1700)$ are strongly model-dependent.Comment: 26 pages, 6 figure

Producing more rice with less water from irrigated systems

Irrigation management / Water use efficiency / Crop production / Water requirements / Water balance / Rice / Water distribution / Irrigated farming / Productivity / On-farm research / Irrigation scheduling / Groundwater / Conjunctive use / Rehabilitation / Modernization / Farmer participation / Farming systems / Irrigation systems / Crop-based irrigation / Asia / Philippines / Sri Lanka / Bangladesh / China / Malaysia / USA

Optimizations of sub-100 nm Si/SiGe MODFETs for high linearity RF applications

Based on careful calibration in respect of 70 nm n-type strained Si channel S/SiGe modulation doped FETs (MODFETs) fabricated by Daimler Chrysler, numerical simulations have been used to study the impact of the device geometry and various doping strategies on device performance and linearity. The device geometry is sensitive to both RF performance and device linearity. Doped channel devices are found to be promising for high linearity applications. Trade-off design strategies are required for reconciling the demands of high device performance and high linearity simultaneously. The simulations also suggest that gate length scaling helps to achieve higher RF performance, but decreases the linearity

Capturing Hiproofs in HOL Light

Hierarchical proof trees (hiproofs for short) add structure to ordinary proof trees, by allowing portions of trees to be hierarchically nested. The additional structure can be used to abstract away from details, or to label particular portions to explain their purpose. In this paper we present two complementary methods for capturing hiproofs in HOL Light, along with a tool to produce web-based visualisations. The first method uses tactic recording, by modifying tactics to record their arguments and construct a hierarchical tree; this allows a tactic proof script to be modified. The second method uses proof recording, which extends the HOL Light kernel to record hierachical proof trees alongside theorems. This method is less invasive, but requires care to manage the size of the recorded objects. We have implemented both methods, resulting in two systems: Tactician and HipCam

An approach to NLO QCD analysis of the semi-inclusive DIS data with modified Jacobi polynomial expansion method

It is proposed the modification of the Jacobi polynomial expansion method (MJEM) which is based on the application of the truncated moments instead of the full ones. This allows to reconstruct with a high precision the local quark helicity distributions even for the narrow accessible for measurement Bjorken $x$ region using as an input only four first moments extracted from the data in NLO QCD. It is also proposed the variational (extrapolation) procedure allowing to reconstruct the distributions outside the accessible Bjorken $x$ region using the distributions obtained with MJEM in the accessible region. The numerical calculations encourage one that the proposed variational (extrapolation) procedure could be applied to estimate the full first (especially important) quark moments

Robots, GPS/GIS, and Programming Technologies: The Power of Digital Manipulatives in Youth Extension Experiences

The study reported here examined the effectiveness of educational robotics combined with GPS/GIS technologies used as digital manipulatives in the teaching of concepts in science, engineering, and technology. Based on the success of previous summer camps, the study also examined a scaling-up of the intervention from 38 participants to 147. The 147 youth (ages 10-15) participated in one of six summer camps held in Nebraska during 2008. Results indicate that participants scored higher on the content posttest than the pretest. The study further examined the differential results. The article makes recommendations for further studies, while acknowledging the potential power of digital manipulatives

The Use of Robotics, GPS and GIS Technologies to Encourage STEM-Oriented Learning in Youth

In our technology rich world, the educational areas of science, technology, engineering, and mathematics (STEM) play an increasingly essential role in developing well-prepared specialists for the 21st century workplace. Unfortunately, interest in theses areas has been declining for a few decades. Various innovative educational initiatives in formal and informal learning environments have been undertaken nationally to attempt to encourage STEM-oriented learning. Funded by the National Science Foundation, the particular program described in this paper focuses on middle school youth in non-formal learning environments. The program integrates educational robotics, Global Positioning System (GPS) and geographic information system (GIS) technologies to provide educational experiences through summer camps, 4-H clubs and afterschool programs. The project’s impact was assessed in terms of: a) youth learning of computer programming, mathematics, geospatial concepts, and engineering/robotics concepts and b) youth attitudes and motivation towards STEM-related disciplines. An increase in robotics/GPS/GIS learning questionnaire scores and a stronger self-efficacy in relevant STEM areas have been found through a set of project-related assessment instruments

Impact of Robotics and Geospatial Technology Interventions on Youth STEM Learning and Attitudes

This study examined the impact of robotics and geospatial technologies interventions on middle school youth’s learning of and attitudes toward science, technology, engineering, and mathematics (STEM). Two interventions were tested. The first was a 40-hour intensive robotics/GPS/GIS summer camp; the second was a 3-hour event modeled on the camp experiences and intended to provide an introduction to these technologies. Results showed that the longer intervention led to significantly greater learning than a control group not receiving the instruction, whereas the short-term intervention primarily impacted youth attitude and motivation. Although the short-term intervention did not have the learning advantages of a more intensive robotics camp, it can serve a key role in getting youth excited about technology and encouraging them to seek out additional opportunities to explore topics in greater detail, which can result in improved learning