Some Aspects of an Early Expression of dominance in White Pine (Pinus strobus L.)

A series of temporary plots was made for the purpose of observing and noting (1) the factors affecting an expression of dominance of white pine (Pinus strobus Linnaeus) and (2) the relationship between dominance and the development of white pine stands. Twenty natural stands and thirteen plantation stands were studied

Direct numerical simulation of heat transport in dispersed gas-liquid two-phase flow using a front tracking approach

In this paper a simulation model is presented for the Direct Numerical Simulation (DNS) of heat transport in dispersed gas-liquid two-phase flow using the Front Tracking (FT) approach. Our model extends the FT model developed by van Sint Annaland et al. (2006) to non-isothermal conditions. In FT an unstructured dynamic mesh is used to represent and track the interface explicitly by a number of interconnected marker points. The Lagrangian representation of the interface avoids the necessity to reconstruct the interface from the local distribution of the fractions of the phases and, moreover, allows a direct and accurate calculation of the surface tension force circumventing the (problematic) computation of the interface curvature. The extended model is applied to predict the heat exchange rate between the liquid and a hot wall kept at a fixed temperature. It is found that the wall-to-liquid heat transfer coefficient exhibits a maximum in the vicinity of the bubble that can be attributed to the locally decreased thickness of the thermal boundary layer

Mechanism for Spontaneous Growth of Nanopillar Arrays in Ultrathin Films Subject to a Thermal Gradient

Several groups have reported spontaneous formation of periodic pillar-like arrays in molten polymer nanofilms confined within closely spaced substrates maintained at different temperatures. These formations have been attributed to a radiation pressure instability caused by acoustic phonons. In this work, we demonstrate how variations in the thermocapillary stress along the nanofilm interface can produce significant periodic protrusions in any viscous film no matter how small the initial transverse thermal gradient. The linear stability analysis of the interface evolution equation explores an extreme limit of B\'{e}nard-Marangoni flow peculiar to films of nanoscale dimensions in which hydrostatic forces are altogether absent and deformation amplitudes are small in comparison to the pillar spacing. Finite element simulations of the full nonlinear equation are also used to examine the array pitch and growth rates beyond the linear regime. Inspection of the Lyapunov free energy as a function of time confirms that in contrast to typical cellular instabilities in macroscopically thick films, pillar-like elongations are energetically preferred in nanofilms. Provided there occurs no dewetting during film deformation, it is shown that fluid elongations continue to grow until contact with the cooler substrate is achieved. Identification of the mechanism responsible for this phenomenon may facilitate fabrication of extended arrays for nanoscale optical, photonic and biological applications.Comment: 20 pages, 9 figure

4-H Youth Development Apprenticeship Program: A Pilot of a New Certification in Youth Development

The field of youth development is expanding, requiring 4-H Extension staff to gain expertise in the field without leaving their jobs to return to school. To address this need, the 4-H Youth Development Practitioner Apprenticeship (YDPA) program was developed under the guidance of the National Association of Extension 4-H Agents and the National 4-H Council through funding from the U. S. Department of Labor. An evaluation of the pilot of YDPA found that staff gained numerous skills needed to effectively serve youth. Suggestions for program continuation are discussed

A Framework for Introducing Program Evaluation to Extension Faculty and Staff

There is an increasing requirement for Cooperative Extension to demonstrate that programs are making an impact on the populations served, yet many staffs have little background in evaluation. This article presents a framework found to be useful in introducing the basics of evaluation to Extension staff. The authors draw upon Jacobs\u27 (1988) Five-Tiered approach to program evaluation and the Joint Committee on Standards for Educational Evaluation (1994) as a base. This foundation allows staff a better understanding of the processes involved in conducting evaluations

The Application of Nuclear Techniques to the Measurement of Moisture and Density of Highway Construction Materials

In recent years much attention has been directed toward the application of neutron and gamma ray techniques to soil moisture and density measurements. This application of radiological measurements of these characteristics of materials of highway construction, of course, is of great interest to the highway industry since the performance of the total pavement system is highly dependent upon the condition of the embankment, subgrade, and base components of this system. An important measure of the state of condition of unconsolidated earth materials is their unit weights and moisture contents. The highway engineer undoubtedly would welcome any method or technique which would provide more rapidly and easily this essential information that may be used in the control of the construction of the embankment, subgrade, and base. The application of the neutron and gamma ray techniques to this purpose appears to offer some promise for the engineer and thus is worthy of his consideration

Interim Report on Rural Secondary, Base Stabilization Projects

Early in 1962, the Division of Rural Highways selected several base stabilization projects for construction during the 1962 season. These projects were to involve the addition of 1-1/2 to 3 inches of compacted granular base to existing, rural secondary, traffic-bound macadam roads. Since these roads were not intended to be surfaced, calcium chloride and sodium chloride were to be added to the additional granular base material in an attempt to retain or hold the aggregate on the road. This treatment was in tended to improve the road and to build up the base over a period of a few years until the road could be surfaced. The Division of Research was requested to observe the construction and performance of these projects and to evaluate the effectiveness of calcium or sodium chloride in this type of stage construction. Accordingly, eight projects totaling 40.111 miles were selected for observation. These projects included three (12.434 miles) in which calcium chloride was used, three (11.200 miles) in which sodium chloride was used, and two (16.477 miles) in which no additive was used. Two additional projects involving similar types of construction are also reported. The Garrard County project was completed however, much of this base material is scattered or washed into the ditches or is pulverized and blown away. This results in an inadequate base when the wearing course is eventually constructed