GPS is the positioning technology of choice for a wide range of land-based applications. Since the mid-1990s GPS products have been on offer for the 'agricultural market'. GPS on its own does not appear to contribute much to improving agricultural productivity. Hence 'precision agriculture' has generally referred to the intergation of GPS within a total system that, for example, uses spatial in...

the earth’s gravity field dedicated missions provide homogeneous and uniformly accurate information on the long wavelengths of the earth’s gravity field. many different global geopotential models have introduced by earth and space research centers during the last years. the geopotential models derived from the grace satellite measurements are compared with the other models at different frequenc...

OBJECTIVE The GRIF automated feedback system produces real-time comments on the appropriateness of diagnostic tests ordered by general practitioners (GPs) based on recommendations from accepted national and regional practice guidelines. We investigated the experiences of GPs with this system and, more specifically, with the recommendations produced by the system as well as their views on using ...

BACKGROUND Measuring the working hours of general practitioners (GPs) is an important but complex task due to the effects of bias related to self-reporting, recall, and stress. In this paper we describe the deployment, feasibility, and implementation of an innovative method for measuring, in real time, GPs' working time, plus the response to the study. METHODS A Short Message Service (SMS) ap...

Background: Based on the target income hypothesis, the economic behavior of physicians is mainly affected by their target income. This study aimed at designing an instrument to explain how general practitioners (GPs) set their desired income.    Methods: A self-administered questionnaire of affecting factors on GPs' target income was extracted from literature reviews and a small qual...

[1] Snow is an important component of the climate system and a critical storage component in the hydrologic cycle. However, in situ observations of snow distribution are sparse, and remotely sensed products are imprecise and only available at a coarse spatial scale. GPS geodesists have long recognized that snow can affect a GPS signal, but it has not been shown that a GPS receiver placed in a s...

Besides their intended use in radionavigation, global positioning system (GPS) satellite signals provide convenient radio beacons for ionospheric studies. Among other propagation phenomena, the ionosphere affects GPS signal propagation through amplitude scintillations that develop after radio waves propagate through ionospheric electron density irregularities. This paper outlines the design, te...

this paper presents a method for generating a digital management map to apply cyanazine pre-emergence herbicide. the main objective was to develop a precision method to generate management maps for the variable rate application of herbicide to reduce the amount of herbicide applied and its adverse impact on the environment. first, local and utm coordinates of a field were determined using total...

Recent technological developments have produced a range of sophisticated and readily available digital tracking technologies, of which the best known is the Global Positioning System [GPS]. Yet, despite this remarkable surge in technology, researchers in the field of tourist studies have failed to take full advantage of what these relatively new systems have to offer. Tracking technologies are ...

in conventional tillage systems, uniform depth tillage is applied over the entire field; however, the depth of hardpan layer varies greatly within the field. site-specific tillage, which modifies physical properties of soil only where the tillage is needed for crop growth, could achieve significant savings in fuel consumption and drawbar power requirements. site-specific tillage can be implemen...