Chemical Sprout Control of Alaska Potatoes.

POTATOES sprout in 11 to 15 weeks after harvest if placed in storage where 'temperatures average 40° F or above. Prior to this, growth regulating substances within the tubers prevent sprouting. If potatoes are stored at room temperature (70° F or higher) their dormant period will be shorter, although differences in varieties are observed. Varieties also differ in habit of sprout growth*. Some develop long sprouts that are relatively easy to remove. Even so, a new crop of sprouts will grow again from the same eyes if storage temperatures remain above 40oF for ten days or more. In addition to the expense of desprouting, potatoes lose weight and their market appeal. Potatoes can be and are stored at 30° to 36° for nearly a year with very little sprouting. Cold storage at this temperature range has some disadvantages. For example, starches are converted to sugar within the tubers. These sugars give cooked potatoes a sweet taste objectionable to some people. Potatoes with a high sugar content are not suitable for chipping and french frying. Sometimes they can be reconditioned by storing at 60° to 70° for a month or more but this warmer environment starts sprouting. Potatoes sprouting extensively in bins (as illustrated in Figure 1) cannot be ventilated properly because sprouts fill the air spaces between tubers. Lack of air movement through the bin causes a low oxygen supply and black heart or b1ack patches soon appear within tubers (Figure 2). Sprouting is costly to Alaskans in that it reduces the number of potatoes meeting U.S. No. 1 grade and therefore reduces farm income.Sprouting is costly to Alaskan's potato industry because it weakens Alaska's competitive position for summer markets. Summer im}:orts of dormant potatoes often capture a large segment of the Alaskan potato market. When these studies were begun, workers in other regions (2, 4, 5, 9) had demonstrated several methods of chemical sprout control. These methods included field spraying of tops, dusfng or dipping of tubers moving into storage, and gas treatment with volatile substances distributed within binned potatoes. Chemicals that had given the best control were methyl ester of naphthaleneacetic acid (MENA), indoleacetic acid (IA), maleic hydrazide (MH) and isopropyl N-(3 chlorophenyl) carbamate (CIPC). In other states MH has become so popular that it has been recently sprayed from an airplane ( 1) and CIPC has been released as an aerosol or vapor (6) within the storage. Some evidence has been presented (3) showing that healing of tender skins and healing of tuber bruises is delayed by sprout inhibitors. Unwashed potatoes frequently carry enough mud or wet soil into storage to inhibit good air movement through the bin. While washing prior to storage eliminates this particular problem, little is known about the storage characteristics of washed treated tubers (10). The objectives of these sh1dies were to learn (1) if sprout inhibitor chemicals used in other regions also inhibit Sf)routing of potatoes grown in Alaska's environment, (2) what effect snrout inhibitors have on yield and quality, (3) when and at what rate the chemical should be applied, (4) how sprout inhibitor treated potatoes store at different temperatures, (5) if washing fieldtreated potatoes prior to storage influences keeping ability or modifies sprout inhibitor action

The SL(2,C) Casson invariant for Dehn surgeries on two-bridge knots

We investigate the behavior of the SL(2,C) Casson invariant for 3-manifolds obtained by Dehn surgery along two-bridge knots. Using the results of Hatcher and Thurston, and also results of Ohtsuki, we outline how to compute the Culler--Shalen seminorms, and we illustrate this approach by providing explicit computations for double twist knots. We then apply the surgery formula of Curtis to deduce the SL(2,C) Casson invariant for the 3-manifolds obtained by p/q-Dehn surgery on such knots. These results are applied to prove nontriviality of the SL(2,C) Casson invariant for nearly all 3-manifolds obtained by nontrivial Dehn surgery on a hyperbolic two-bridge knot. We relate the formulas derived to degrees of A-polynomials and use this information to identify factors of higher multiplicity in the $\hat{A}$-polynomial, which is the A-polynomial with multiplicities as defined by Boyer-Zhang.Comment: 32 pages, 2 figures, to be published in Algebraic and Geometric Topolog

Determination of optimum sunlight concentration level in space for 3-5 cascade solar cells

The optimum range of concentration levels in space for III-V cascade cells was calculated using a realistic solar cell diode equation. Temperature was varied with concentration using several models and ranged from 55 C at 1 sun to between 80 and 200 C at 100 suns. A variety of series resistance and internal resistances were used. Coefficients of the diffusion and recombination terms are strongly temperature dependent. The study indicates that the maximum efficiency of 30 percent occurs in the 50 to 100 sun concentration range provided series resistance is below 0.015 ohm-sq cm and cell temperature is about 80 C at 100 suns

THE CHANGING DEMAND STRUCTURE FOR PORK AND BEEF IN THE 1970S: IMPLICATIONS FOR THE 1980S

Demand and Price Analysis,

Effect of atmospheric parameters on silicon cell performance

The effects of changing atmospheric parameters on the performance of a typical silicon solar cell were calculated. The precipitable water vapor content, airmass and turbidity were varied over wide ranges and the normal terrestrial distribution of spectral irradiance was studied. The cell short-circuit current was then computed for each spectral irradiance distribution using the cell spectral response. Data are presented in the form of calibration number (cell current/incident irradiance) vs. water vapor content or turbidity

Results of module electrical measurement of the DOE 46-kilowatt procurement

Current-voltage measurements have been made on terrestrial solar cell modules of the DOE/JPL Low Cost Silicon Solar Array procurement. Data on short circuit current, open circuit voltage, and maximum power for the four types of modules are presented in normalized form, showing distribution of the measured values. Standard deviations from the mean values are also given. Tests of the statistical significance of the data are discussed

DISCUSSION: AGRICULTURAL ECONOMISTS IN RURAL DEVELOPMENT: RESPONSIBILITIES, OPPORTUNITIES, RISKS, AND PAYOFFS

Community/Rural/Urban Development,

AN ANALYSIS OF FACTORS INFLUENCING REGIONAL LABOR FORCE MIGRATION, 1960-1970

Labor and Human Capital,

Operational performance of a low cost, air mass 2 solar simulator

Modifications and improvements on a low cost air mass 2 solar simulator are discussed. The performance characteristics of total irradiance, uniformity of irradiance, spectral distribution, and beam subtense angle are presented. The simulator consists of an array of tungsten halogen lamps hexagonally spaced in a plane. A corresponding array of plastic Fresnel lenses shapes the output beam such that the simulator irradiates a 1.2 m by 1.2 m area with uniform collimated irradiance. Details are given concerning individual lamp output measurements and placement of the lamps. Originally, only the direct component of solar irradiance was simulated. Since the diffuse component may affect the performance of some collectors, the capability to simulate it is being added. An approach to this diffuse addition is discussed

Overregulation of Health Care: Musings on Disruptive Innovation Theory

Disruptive innovation theory provides one lens through which to describe how regulations may stifle innovation and increase costs. Basing their discussion on this theory, Curtis and Schulman consider some of the effects that regulatory controls may have on innovation in the health sector