2,849 research outputs found
On the local structure of Dirac manifolds
We give a local normal form for Dirac structures. As a consequence, we show
that the dimensions of the pre-symplectic leaves of a Dirac manifold have the
same parity. We also show that, given a point of a Dirac manifold ,
there is a well-defined transverse Poisson structure to the pre-symplectic leaf
through . Finally, we describe the neighborhood of a pre-symplectic leaf
in terms of geometric data. This description agrees with that given by Vorobjev
for the Poisson caseComment: minor correction
Stability of higher order singular points of Poisson manifolds and Lie algebroids
We study the stability of singular points for smooth Poisson structures as
well as general Lie algebroids. We give sufficient conditions for stability
lying on the first (not necessarily linear) approximation of the given Poisson
structure or Lie algebroid at a singular point. The main tools used here are
the classical Lichnerowicz-Poisson cohomology and the deformation cohomology
for Lie algebroids recently introduced by Crainic and Moerdijk. We also provide
several examples of stable singular points of order for Poisson
structures and Lie algebroids. Finally, we apply our results to pre-symplectic
leaves of Dirac manifolds.Comment: corrected typo
Debt Relief, Demand for Eduction, and Poverty
government expenditures, debt, poverty, schooling
The State of âDifferently Abledâ People in the Western Cape, South Africa
This project is a look into whether the current legislation and resources provided allow for the equality that is promised in the new constitution. I looked at legislation and community NGOs in order to establish what is being done in order to assure that people with disabilities have equal access to resources, including education, transportation, employment, healthcare, public awareness, and human resource development. In order to investigate these questions I worked with the Cape Mental Health Society and the Fountain House; I conducted interviews and observations looking at the community facilities of care. These community groups also provided insight into the translation of legislation to the people it is intended to serve. After I finished my research, I concluded that South Africa has progressive legislation when it comes to the actual laws being signed. However, these laws are ineffective and poorly implemented, thus creating a system of exclusion. As a result of poor implementation, resources are not being allocated to people with disabilities, thus people with disabilities are operating in a system that promotes exclusion. Additionally, the Healthcare 2010 policy is one that is supposed to increase the quality of care for people, based on community service, but people with disabilities are simply being removed from the hospitals and overloading into under funded community NGOs. Finally, I conclude that a complete shift, in terms of philosophy on disability, is needed in order to truly accomplish equality for people with disabilities
MARKET STRUCTURE AND SPATIAL PRICE DYNAMICS
A method was developed with time series models to test hypotheses about the relationship between market structure and spatial price dynamics. Long-run dynamic multipliers measuring the magnitude of lagged adjustments for spatial milled rice prices were calculated from the time series model and used as the dependent variable in a regression model that included a number of factors expected to influence price determination. Results show that price adjustments were slower as regional submarket concentration increased and were faster in the regions with a higher market share. Arkansas, the state with the largest market share, was consistently a price leaderDemand and Price Analysis, Industrial Organization,
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Modelling fixed plant and algal dynamics in rivers: an application to the River Frome
The development of eutrophication in river systems is poorly understood given the complex relationship between fixed plants, algae, hydrodynamics, water chemistry and solar radiation. However there is a pressing need to understand the relationship between the ecological status of
rivers and the controlling environmental factors to help the reasoned implementation of the Water Framework Directive and Catchment Sensitive Farming in the UK. This research aims to create a dynamic, process-based, mathematical in-stream model to simulate the growth and competition of different vegetation types (macrophytes, phytoplankton and benthic algae) in rivers. The model,
applied to the River Frome (Dorset, UK), captured well the seasonality of simulated vegetation types (suspended algae, macrophytes, epiphytes, sediment biofilm). Macrophyte results showed that local knowledge is important for explaining unusual changes in biomass. Fixed algae simulations indicated the need for the more detailed representation of various herbivorous grazer groups,
however this would increase the model complexity, the number of model parameters and the required observation data to better define the model. The model results also highlighted that simulating only phytoplankton is insufficient in river systems, because the majority of the suspended algae have benthic origin in short retention time rivers. Therefore, there is a need for modelling tools that link the benthic and free-floating habitats
Should Grain Elevator Managers Adopt Integrated Pest Management?
Insect infestation during storage and processing causes millions of dollars of wheat damage annually in the United States. Insect infestation reduces wheat storing processing profit as well as consumer confidence in wheat food products. Meanwhile, increased concerns about insecticide use have increase interest in Integrated Pest Management (IPM) strategies. This research compares the costs of IPM and chemical-based approaches to insect control to determine why most elevator managers have not adopted IPM practices.Agribusiness,
Wireless Acoustic Measurement System
A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in "Predicting Rocket or Jet Noise in Real Time" (SSC-00215-1), which appears elsewhere in this issue of NASA Tech Briefs. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro-ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that provides an intuitive graphical user interface through which an operator at the control server can control the operations of the field stations for calibration and for recording of measurement data. A test engineer positions and activates the WAMS. The WAMS automatically establishes the wireless network. Next, the engineer performs pretest calibrations. Then the engineer executes the test and measurement procedures. After the test, the raw measurement files are copied and transferred, through the wireless network, to a hard disk in the control server. Subsequently, the data are processed into 1/3-octave spectrograms
Versatile IEEE-488 data acquisition and control routines for a diode array spectrophotometer
The UV-visible diode array spectrophotometer is a work-horse
instrument for many laboratories. This article provides simple data acquisition and control routines in Microsoft QuickBasic for a HP-8452A diode array spectrophotometer interfaced to an IBM PC/XT/AT, or compatible, microcomputer. These allow capture of full spectra and measure absorbance at one or several wavelengths at preset time intervals. The variance in absorbance at each wavelength is available as an option
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