Earnings of Black and White Youth and Their Relation to Poverty

This paper examines the relation between youth employment and poverty for black and white families. An increase in the employment proportions of black men ages 16–19, which have lagged far behind their white counterparts, would reduce poverty among blacks to a moderate but meaningful degree. We provide evidence of a small positive feedback relation between black youth employment and family incomes that would magnify gains in both variables if either variable were increased. We also provide evidence that improvements in labor market conditions that affect youth employment, in the educational attainments of black youth, and in other policy-related variables would raise both youth employment and their family incomes.

A hierarchy of compatibility and comeasurability levels in quantum logics with unique conditional probabilities

In the quantum mechanical Hilbert space formalism, the probabilistic interpretation is a later ad-hoc add-on, more or less enforced by the experimental evidence, but not motivated by the mathematical model itself. A model involving a clear probabilistic interpretation from the very beginning is provided by the quantum logics with unique conditional probabilities. It includes the projection lattices in von Neumann algebras and here probability conditionalization becomes identical with the state transition of the Lueders - von Neumann measurement process. This motivates the definition of a hierarchy of five compatibility and comeasurability levels in the abstract setting of the quantum logics with unique conditional probabilities. Their meanings are: the absence of quantum interference or influence, the existence of a joint distribution, simultaneous measurability, and the independence of the final state after two successive measurements from the sequential order of these two measurements. A further level means that two elements of the quantum logic (events) belong to the same Boolean subalgebra. In the general case, the five compatibility and comeasurability levels appear to differ, but they all coincide in the common Hilbert space formalism of quantum mechanics, in von Neumann algebras, and in some other cases.Comment: 12 page

States of quantum systems and their liftings

Let H(1), H(2) be complex Hilbert spaces, H be their Hilbert tensor product and let tr2 be the operator of taking the partial trace of trace class operators in H with respect to the space H(2). The operation tr2 maps states in H (i.e. positive trace class operators in H with trace equal to one) into states in H(1). In this paper we give the full description of mappings that are linear right inverse to tr2. More precisely, we prove that any affine mapping F(W) of the convex set of states in H(1) into the states in H that is right inverse to tr2 is given by the tensor product of W with some state D in H(2). In addition we investigate a representation of the quantum mechanical state space by probability measures on the set of pure states and a representation -- used in the theory of stochastic Schroedinger equations -- by probability measures on the Hilbert space. We prove that there are no affine mappings from the state space of quantum mechanics into these spaces of probability measures.Comment: 14 page

Irrigation and disease management of vegetables

Wise use of irrigation may help farmers to reduce fungicide applications on vegetable crops. Such a reduction is potentially significant when one considers that irrigation, fertilizer, and pesticide use account for more than 50 percent of the energy expended in fresh vegetable production

Pesticide Sprays to Control Botrytis Rot, Anthracnose, and Tarnished Plant Bug In Day-Neutral Strawberries, 1992

The trial was held at the Iowa State University Horticulture Farm. Day-neutral strawberries planted into plastic mulch in May 1992 on sandy loam soil (fine, loamy, mixed mesic, Typic Hapludoll) were arranged in a randomized complete block design with five treatments and four replications. Each block consisted of five 20-ft-long double rows of plants with 12-in spacing between plants in the double rows, and each 20-ft segment was a treatment subplot. In three treatments ( post-infection ), timing of fungicide sprays was based on a leaf wetness-temperature model proposed by M. Ellis (pers. comm., Department of Plant Pathology, OARDC, Wooster, OH, and Bulger et al, Phytopathology 77:1225-1230) for control of Botrytis fruit rot. In the same treatments, timing of insecticide sprays for tarnished plant bug (IPB) were based on thresholds of TPB counts; a spray was applied when the mean number of TPB\u27s (sum of nymphs and adults) per fruit cluster equaled or exceeded the threshold number. TPB numbers were assessed 2x/week by beating 10 fruit clusters per plot (one cluster per sampled plant) twice over a white plastic dish and counting TPB nymphs and adults in the dish. A fourth treatment ( weekly ) was a weekly spray of fungicides and insecticides, and a fifth treatment ( unsprayed ) received no pesticide sprays. Pesticide spraying was started as berries began to ripen (14 Jul). Fungicides used (rates per 100 gal) were Ronilan FL (0.5 pt) plus Benlate 50 WP (4 oz). After 17 Aug, when anthracnose had become severe, Captan 50 WP (2 lb) was substituted for Benlate. The insecticide used was Sevin 50 WP (2 lb). Pesticides were applied to runoff using a Solo backpack sprayer (Model No. 425) with a flat-fan nozzle at approximately 30 psi. Leaf wetness and temperature were measured approximately 0.3 mi from the strawberry plot, using a CR- 10 micrologger and appropriate sensors (Campbell Scientific, Logan, Ul). Ripe fruit were picked by hand, counted, and weighed 1 to 3x/ wk. At each picking, damaged berries were classed by the probable source of damage, and these classes were counted and weighed

Adapting predictive models to reduce fungicide sprays on tomatoes in Iowa

Iowa tomato growers face critical challenges in pest control. The public is concerned about the health risks of pesticide residues on fruits and vegetables as well as environmental contamination; the result has been fewer, more restricted, more expensive pesticide products for minor crops such as tomatoes. At the same time, the market continues to demand high-quality, abundant, blemish-free produce