11,359 research outputs found
Utilizing Community Resources to Reduce the Presence of Type 2 Diabetes in Rural Youth
The purpose of this study was to implement a program designed to promote diabetes prevention activities among preadolescents in a rural southern setting using a day camp intervention. Participants in the study were eleven youth from a rural Alabama county who participated in a week-long half-day camp administered by local and community volunteers. Change scores were used to compare pre- to post- to follow-up measures for camp participant responses. Program results consistently demonstrated that the day camp was theoretically sound and that program activities positively impacted behavioral antecedents. This study demonstrated the feasibility of conducting a diabetes prevention day camp in a rural environment. Insights from this intervention can assist planners in rural environments to tailor similar initiatives in rural settings. Given the complicated nature of behavior change, a day camp approach of this length does not modify the behaviors of participants. Behavior changes may take considerably longer to initiate
Locality and topology in the molecular Aharonov-Bohm effect
It is shown that the molecular Aharonov-Bohm effect is neither nonlocal nor
topological in the sense of the standard magnetic Aharonov-Bohm effect. It is
further argued that there is a close relationship between the molecular
Aharonov-Bohm effect and the Aharonov-Casher effect for an electrically neutral
spin particle encircling a line of charge.Comment: 3 pages, no figure
Push clocks: a new approach to charge-coupled devices clocking
A new approach to charge-coupled device clocking has been developed—dynamic push clocks. With dynamic push clocks, the charge is transferred by pushing it from one storage site to another. The push clock approach results in a larger signal dynamic range, larger signal-to-noise ratio, and better performance at both high and low frequencies
Advanced technology applications for second and third general coal gasification systems
The historical background of coal conversion is reviewed and the programmatic status (operational, construction, design, proposed) of coal gasification processes is tabulated for both commercial and demonstration projects as well as for large and small pilot plants. Both second and third generation processes typically operate at higher temperatures and pressures than first generation methods. Much of the equipment that has been tested has failed. The most difficult problems are in process control. The mechanics of three-phase flow are not fully understood. Companies participating in coal conversion projects are ordering duplicates of failure prone units. No real solutions to any of the significant problems in technology development have been developed in recent years
Schottky Barrier Gate Field Effect Transistor
An obvious addition to the ever-growing family of field-effect devices is a field-effect transistor with a Schottky barrier gate. It is the purpose of this correspondence 1) to demonstrate that indeed such a device does function as expected and 2) to point out several advantages of such a structure under certain circumstances. A schematic cross section of the device is shown in Fig. 1. The gate consists of a metal in intimate contact with the clean semiconductor surface. Clearly the ohmic contacts can be placed either on top of or under the semiconductor layer
Electronic Current Flow Through Ideal Dielectric Films
During the past few decades a large literature has accumulated on the subject of current flow through dielectric films. Much of this material contains detailed analyses of many physical effects and a
great deal of multiparameter curve fitting. Until recently all this activity had given the field a rather bad name, since it appeared that all effects were very complicated and nothing could be understood in a first-principles way. It is true, in fact, that in many thin-film
systems the current flow is dominated by impurities, trapping processes, and so on, so that no simple, clear picture emerges for the mechanism of current flow. However, in the past few years it has become clear that certain insulating materials behave in a nearly ideal
fashion and can be understood in a very simple and fundamental way.
In this chapter I shall not attempt to discuss the mass of literature dealing with data on dielectrics that were not well characterized and well understood. Instead, I shall concentrate on examples in which nearly ideal behavior was observed and in which the simple physics of the current-flow processes is clear. In retrospect it seems
obvious that much of the previous data is also understandable on rather simple grounds and that there were a number of conceptual errors that led to the belief that vastly complicated processes were involved. This is by no means true for all the data in the literature,
but certainly with good hindsight resulting from a clear understanding of ideal materials, a much better understanding of the nonideal cases
is also possible. Since the details of all the results I shall cite are available in the published literature, I shall discuss only the ideas and basic principles involved and give references where a more complete
discussion may be found
Physics of Interfaces
It has long been known that when a metal is placed in contact with a semiconductor a rectifying contact often results. This rectification is a result
of an energy barrier between the metal and the semiconductor. In order to form a nonrectifying or ohmic contact, two general approaches can be applied: either (1) the barrier energy can be reduced to a low
enough value that the thermally excited current over the barrier is large enough for the application involved or (2) the semiconductor can be doped to a high carrier density to allow quantum mechanical tunneling to take
place. The physical principles of these processes are discussed in this article
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