USING USDA FRESH FRUIT AND VEGETABLE ARRIVALS TO DETERMINE THE DISTRIBUTION OF A STATE'S PRODUCTION

This paper examines the problem of transforming information on fresh fruit and vegetable Arrivals to U.S. Metropolitan Statistical Areas into a distribution of products to larger geographical regions. Three methods for the regional distribution of Florida-grown produce are compared. A new method, which takes into account regional population sizes in the allocation of an area's produce to the region, is shown to produce allocations similar to those obtained through trucker surveys. Finally, the new approach is applied to produce from other areas, and allocations to regions compared to that obtained using the Arrivals data only.Crop Production/Industries,

Sea turtle nesting in the Ten Thousand Islands of Florida

Loggerhead sea turtles (Caretta caretta) nest in numerous substrate and beach types within the Ten Thousand Islands (TTl) of southwest Florida. Nesting beach selection was analyzed on 12 islands within this archipelago. Numerous physical characteristics were recorded to identify the relatedness of these variables and determine their importance for nesting beach selection in C. caretta. These variables were chosen after evaluating the islands, conducting literature searches and soliciting personal communications. Along transects, data were collected, on the following: height of canopy, beach width, overall slope (beach slope and slope of offshore approach) and sand samples analyzed for pH, percentage of water, percentage of organic content, percentage of carbonate and particle size (8 size classes). Data on ordinal aspect of beaches and beach length were also recorded and included in the analysis. All of the variables were analyzed by tree regression, incorporating the nesting data into the analysis. In the TTl, loggerheads appear to prefer wider beaches (p< 0.001; R2 = 0.56) that inherently have less slope, and secondarily, wider beaches that have low amounts of carbonate (p< O.00 1). In addition, C. caretta favors nest sites within or in close proximity to the supra-littoral vegetation zone of beaches in the TTl (p< 0.001). (86 page document

Frequency shifts of photoassociative spectra of ultracold metastable Helium atoms : a new measurement of the s-wave scattering length

We observe light-induced frequency shifts in one-color photoassociative spectra of magnetically trapped $^4$He$^*$ atoms in the metastable $2^3S_1$ state. A pair of ultracold spin-polarized $2^3S_1$ helium atoms is excited into a molecular bound state in the purely long range $0_u^+$ potential connected to the $2^3S_1 - 2^3P_0$ asymptote. The shift arises from the optical coupling of the molecular excited bound state with the scattering states and the bound states of two colliding $2^3S_1$ atoms. We measure the frequency-shifts for several ro-vibrational levels in the $0^+_u$ potential and find a linear dependence on the photoassociation laser intensity. Comparison with a theoretical analysis provides a good indication for the s-wave scattering length $a$ of the quintet ($^5\Sigma_g^+$) potential, $a=7.2\pm 0.6$ nm, which is significantly lower than most previous results obtained by non-spectroscopic methods.Comment: 7 pages, 4 figure

Accurate determination of the scattering length of metastable Helium atoms using dark resonances between atoms and exotic molecules

We present a new measurement of the s-wave scattering length a of spin-polarized helium atoms in the 2^3S_1 metastable state. Using two-photon photoassociation spectroscopy and dark resonances we measure the energy E_{v=14}= -91.35 +/- 0.06 MHz of the least bound state v=14 in the interaction potential of the two atoms. We deduce a value of a = 7.512 +/- 0.005 nm, which is at least one hundred times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of 1 microsecond.Comment: 4 pages, 4 figure

USING TREE REGRESSION TO IDENTIFY NUTRITIONAL AND ENVIRONMENTAL FACTORS AFFECTING SUGARCANE PRODUCTION

A prediction function is developed for sugarcane yield using preplant soil nutrition levels, cultivar, and soil type. A tree regression approach is used because the resulting function encompasses the complexity of response between yield, multiple nutrients and other factors, while handling large amounts of data and providing information useful in the development of fertilizer and other production recommendations. Data collected from 148 control plots of experiments performed on commercial fields in the Everglades Agricultural Area of Florida are used to illustrate the method

Tuning decoherence with a voltage probe

We present an experiment where we tune the decoherence in a quantum interferometer using one of the simplest object available in the physic of quantum conductors : an ohmic contact. For that purpose, we designed an electronic Mach-Zehnder interferometer which has one of its two arms connected to an ohmic contact through a quantum point contact. At low temperature, we observe quantum interference patterns with a visibility up to 57%. Increasing the connection between one arm of the interferometer to the floating ohmic contact, the voltage probe, reduces quantum interferences as it probes the electron trajectory. This unique experimental realization of a voltage probe works as a trivial which-path detector whose efficiency can be simply tuned by a gate voltage

A NEW APPROACH TO TEACHING NATURAL RESOURCE SAMPLING

A basic undergraduate course in statistics is often not adequate for students in renewable natural resource programs such as wildlife, forestry, fisheries, and related subjects. A strong foundation in the basics of sampling in time and space of forest, vegetation, wildlife and fish populations is needed. A brief account of our experience in teaching such a course over the last three years along with progress on developing course-related material and activities is reported. This includes the development of: 1) computer-based simulations; 2) in-class participation simulations to illustrate the basic concepts of sampling in space and time; 3) exercises to introduce students to basic field sampling methods (quadrat, line and point sample units, mark/recapture, radio telemetry, etc.); and 4) an associated hypermedia text. From the beginning, emphasis is placed on cost-effectiveness and on the importance of sampling in the decision-making process. Students are required to develop their own sampling project, implement the project, present the results in an open forum, and prepare an associated report in the format of a scientific paper

Controlled Synthesis of β-SiC Nanopowders with Variable Stoichiometry Using Inductively Coupled Plasma

In the growing field of nanomaterials, SiC nanoparticles arouse interest for numerous applications. The inductively coupled plasma (ICP) technique allows obtaining large amount of SiC nanopowders from cheap coarse SiC powders. In this paper, the effects on the SiC structure of the process pressure, the plasma gas composition, and the precursor nature are addressed. The powders were characterized by X-ray diffraction (XRD), Raman and fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and high resolution electron microscopy (HREM), chemical analyses, BET and photon correlation spectroscopy (PCS) measurements. Whatever the precursor (α- or β-SiC), the nanoparticles were crystallised in the cubic β-SiC phase, with average sizes in the 20-40nm range. Few residual grains of precursor were observed, and the decarburization due to the reductive Ar-H2 plasma lead to the appearance of Si nanograins. The stoichiometry of the final product was found to be controllable by the process pressure and the addition of methan