Investigating the Light Scalar Mesons

We first briefly review a treatment of the scalars in meson meson scattering based on a non-linear chiral Lagrangian, with unitarity implemented by a "local" modification of the scalar propagators. It is shown that the main results are confirmed by a treatment in the SU(3) linear sigma model in which unitarity is implemented "globally". Some remarks are made on the speculative subject of the scalars' quark structure.Comment: 9 pages,3 figures,talk at hadron2001, Protvin

Complementary Ansatz for the neutrino mass matrix

We propose a simple Ansatz for the three generation neutrino mass matrix $M_\nu$ which is motivated from an SO(10) grand unified theory. The Ansatz can be combined with information from neutrino oscillation experiments and bounds on neutrinoless double beta decay to determine the neutrino masses themselves and to reconstruct, with some assumptions, the matrix $M_\nu$ .Comment: 15 pages, RevteX, submitted to Phys. Rev.

Charmonium-Nucleon Dissociation Cross Sections in the Quark Model

Charmonium dissociation cross sections due to flavor-exchange charmonium-baryon scattering are computed in the constituent quark model. We present results for inelastic $J/\psi N$ and $\eta_c N$ scattering amplitudes and cross sections into 46 final channels, including final states composed of various combinations of $D$, $D^*$, $\Sigma_c$, and $\Lambda_c$. These results are relevant to experimental searches for the deconfined phase of quark matter, and may be useful in identifying the contribution of initial $c\bar c$ production to the open-charm final states observed at RHIC through the characteristic flavor ratios of certain channels. These results are also of interest to possible charmonium-nucleon bound states.Comment: 10 pages, 5 eps figures, revte

An analytical method to predict efficiency of aircraft gearboxes

A spur gear efficiency prediction method previously developed by the authors was extended to include power loss of planetary gearsets. A friction coefficient model was developed for MIL-L-7808 oil based on disc machine data. This combined with the recent capability of predicting losses in spur gears of nonstandard proportions allows the calculation of power loss for complete aircraft gearboxes that utilize spur gears. The method was applied to the T56/501 turboprop gearbox and compared with measured test data. Bearing losses were calculated with large scale computer programs. Breakdowns of the gearbox losses point out areas for possible improvement

Does Subsidizing Fertilizer Increase Yields? Evidence from Malawi

Despite their strain on government and donor budgets, fertilizer subsidies have once again become popular policy tools in several Sub-Saharan Africa countries as a potential way to increase yields in staple crops like maize. Policy makers often assume that farmers who receive the subsidy will achieve yield responses that are similar to those obtained by farmers who pay commercial prices for the input. This notion has not been verified empirically. Our study uses panel data from Malawi, a country that recently implemented a fertilizer subsidy program, to compare maize yield response to fertilizer from farmers who received subsidized fertilizer with yield responses from those who paid commercial prices for the input. Descriptive results indicate that maize plots using commercial fertilizer obtain higher yields per kilogram of fertilizer than maize plots that used subsidized fertilizer. Conversely, the results obtained using a fixed-effects estimator indicate that when other factors are controlled for, maize plots that use subsidized fertilizer obtain a higher yield response than other plots. The results seems to be influenced by a group of farmers who used no fertilizer before the subsidy program began, but used subsidized fertilizer after the program was implemented. This group of farmers obtained significantly higher yields in the year when they receive the subsidy than did the rest of the farmers in the sample during that year. These findings indicate that in order to be effective, government officials should specifically target fertilizer subsidies to farmers who lack access to commercial markets or would not otherwise find it profitable to purchase the input.Malawi, Fertilizer Subsidies, Production Function, Crop Production/Industries,

X-ray polarimetry with an active-matrix pixel proportional counter

We report the first results from an X-ray polarimeter with a micropattern gas proportional counter using an amorphous silicon active matrix readout. With 100% polarized X-rays at 4.5 keV, we obtain a modulation factor of 0.33 +/- 0.03, confirming previous reports of the high polarization sensitivity of a finely segmented pixel proportional counter. The detector described here has a geometry suitable for the focal plane of an astronomical X-ray telescope. Amorphous silicon readout technology will enable additional extensions and improvements.Comment: 4 pages, 4 figures, 1 tabl

Learning to Dress {3D} People in Generative Clothing

Three-dimensional human body models are widely used in the analysis of human pose and motion. Existing models, however, are learned from minimally-clothed 3D scans and thus do not generalize to the complexity of dressed people in common images and videos. Additionally, current models lack the expressive power needed to represent the complex non-linear geometry of pose-dependent clothing shapes. To address this, we learn a generative 3D mesh model of clothed people from 3D scans with varying pose and clothing. Specifically, we train a conditional Mesh-VAE-GAN to learn the clothing deformation from the SMPL body model, making clothing an additional term in SMPL. Our model is conditioned on both pose and clothing type, giving the ability to draw samples of clothing to dress different body shapes in a variety of styles and poses. To preserve wrinkle detail, our Mesh-VAE-GAN extends patchwise discriminators to 3D meshes. Our model, named CAPE, represents global shape and fine local structure, effectively extending the SMPL body model to clothing. To our knowledge, this is the first generative model that directly dresses 3D human body meshes and generalizes to different poses. The model, code and data are available for research purposes at https://cape.is.tue.mpg.de.Comment: CVPR-2020 camera ready. Code and data are available at https://cape.is.tue.mpg.d

Maize Yield Response to Fertilizer and Profitability of Fertilizer Use Among Small-Scale Maize Producers in Zambia

Multi-year nationwide survey data is used to estimate maize yield response functions and determine profitability of fertilizer use by small-scale farmers in Zambia. There has been a dearth of empirical studies on economics of fertilization in the context of Sub-Saharan Africa. In this paper we identify major methodological issues arising from using survey data and estimate maize yield response functions for small-scale rural households that have various management practices and soil conditions in two major agro-climatic zones. Profitability of fertilizer use is determined for each group of households. Our findings provide the following key messages. First, households that obtained fertilizer on time and used animal draught power or mechanical power for land preparation are more likely to find fertilizer use profitable than other households with similar agro-ecological and market access conditions. Second, farmers' proximity to the provincial centers has a significant impact on the profitability of fertilizer use. Greater distances and transport costs from provincial centers erode the profitability of fertilizer use. Third, high interest rates also reduce the profitability of fertilizer use. Small farmers may find fertilizer use unprofitable until efforts are made to reduce transportation costs and interest rates as well as to ensure more timely delivery of fertilizer.Maize, Yield, Fertilizer, Profitability, Survey data, Crop Production/Industries,

Molecular clouds in the centers of galaxies: Constraints from HCN and CO-13 line emission

We have searched for HCN J=1-0 line emission in the centers of 12 galaxies and have detected it in 10 of them. We have obtained complementary data on J=1-0 and 2-1 transitions of CO-12 and CO-13 in these systems. The ratio of integrated intensities, I(CO 1-0)/I(HCN 1-0) = 25 +/- 11 for this sample. We find that HCN emission of this strength can be produced under conditions of subthermal excitation. In combination with the line ratios in CO and CO-13, HCN puts constraints on the mean conditions of molecular clouds and on the mix of cloud types within the projected beam

PROFITABILITY OF FERTILIZER USE ON MAIZE BY SMALL-SCALE FARMING HOUSEHOLDS IN ZAMBIA

Multi-year nationwide survey data is used to estimate maize yield response functions and determine profitability of fertilizer use by small-scale farmers in Zambia. Most previous research on economics of fertilization used estimates of yield response to nutrients based on experimental or simulation data and seldom investigated region-specific and management-specific effects. In this paper we address the main issues arising from using large survey data and estimate maize yield response functions for different groups of households that have various management practices and soil conditions in two major agro-climatic zones. Profitability of fertilizer use is determined for each group in each zone and the results provide the following messages. First, households that obtained fertilizer on time and used animal draught power or mechanical power for land preparation are more likely to find fertilizer use profitable than other groups of households located in the same district. Second, farmers' proximity to the provincial centers has a significant impact on the profitability of fertilizer use. Greater distances and transport costs from provincial centers erode the profitability of fertilizer use. Third, high time preferences for money also reduce the profitability of fertilizer use. Thus, despite achieving relatively high physical crop response rates to fertilizer use in some areas, small farmers may find fertilizer use unprofitable until efforts are made to reduce transportation costs and implicit interest rates as well as to ensure more timely delivery of fertilizer.Farm Management,