The feasibility of low-G grey solidification of nodular iron in the F-104 experimental furnace package

The rationale for low-g experiments with cast iron and the need for solidification in the grey form during these experiments are reviewed. The factors which determine whether an iron melt will solidify grey or white are discussed. Cooling rate versus microstructure was studied for a nodular iron candidate material for F-104 low-g solidification. The study determined that low-g grey solidification, using the present F-104 furnace system, of the nodular iron composition studied is not feasible. Specimen microstructure strongly suggested that the F-104 furnace's gas cooling system was causing excessive localized chill resulting in the nucleation of the unwanted iron carbide phase. A change is suggested, in the quench system design, that could possibly overcome this problem

Economies of Size of Cattle Ranches and Wheat Farms and a Comparison of Management Alternatives for Marginal Cropland in Utah

Five long-run average cost curves were derived from questionnaire and interview data by connecting points corresponding to the per unit production costs and levels of beef output for four cattle ranch sizes (50, 150, 300, and 500 head of breeding cows). Analysis of the long-run average cost curves in combination with the 1968 weighted Utah beef price revealed that all four ranch sizes studied are capable of meeting cash costs. If the goal of the ranch operator is to meet both cash costs and depreciation, a cattle ranch supporting 105 breeding cows is the minimum size necessary. If provision is made to cover cash costs and depreciation in addition to receiving a fair return for operator and family labor, the ranch must support at least 360 breeding cows. None of the four ranch sizes studied were capable of meeting all production costs including five per cent interest on investment. The minimum ranch size necessary to cover all production costs including 1 . 4 per cent interest on investment is 500 head of breeding cows. Farmer questionnaires and the machine capacity technique provided data from which five long-run average cost curves were derived by connecting points representing average production costs and levels of wheat output for four sizes of wheat farms (500, 1000, 2000, and 3000 acres). The long-run average cost curves were analyzed in combination with the 1968 Utah wheat price. All four wheat farm sizes studied are capable of meeting cash costs. In order to cover both cash costs and depreciation a wheat farm of at least 940 acres is required. The minimum wheat farm size necessary to meet cash costs and depreciation as well as provide a fair return to operator and family labor is 2430 acres. None of the four sizes of wheat farms studied was large enough to cover all costs including interest on investment at five per cent. In order to cover all production costs including 0,64 per cent interest on investment a wheat farm of at least 3000 acres is required, Costs and returns to five management alternatives for marginal Utah cropland ( (1) wheat production by owner-operator, (2) leasing crop.. land to tenants for dryland wheat production, (3) leasing forage on an AUM basis, (4) leasing of forage on a livestock gain basis, and (5) stocker cattle production by the land owner) were compared in the shortrun, in the long-run assuming that all inputs were variable, and in the long-run assuming that land and operator and family labor were fixed, For the marginal cropland owner who also owns wheat production factors, wheat production on an owner-operator basis is the most favorable short-run alternative. Wheat production on a tenant basis is the only short-run alternative open to cropland owners who own neither wheat production factors nor the improvements necessary for grazing enterprises. Leasing forage on a livestock gain basis is the most favorable short-run alternative for cropland owners whose holdings are equipped with grazing improvements. For the long-run situation in which all inputs were considered variable, all five management alternatives yielded negative returns. Under such conditions a rational land owner would refuse to choose from among the five alternatives studied and would instead liquidate his land holdings. When operator and family labor and land were considered fixed, leasing cropland to tenants for dryland wheat production proved to be the most favorable long-run management alternative. Showing the second highest internal rate of return was leasing forage on a livestock gain basis followed ~ stocker cattle production by the land owner. Wheat production ~ the land owner and leasing forage on an AUM basis proved to be the least favorable long-run management alternatives on marginal cropland

In vitro antitumour activity of the novel imidazoisoquinoline SDZ 62-434.

The novel imidazoisoquinoline SDZ 62-434, originally identified as a platelet-activating factor (PAF) antagonist, has antiproliferative activity in a range of cell lines from human solid and haematological malignancies. Using an MTT cytotoxicity assay, IC50 values of 5 microM - 111 microM were observed following a 24 h exposure. Similar results were obtained using a clonogenic assay. The HT29 colon adenocarcinoma was particularly sensitive while the MCF-7 breast carcinoma was the most resistant in our panel. Only a 2-3 fold cross-resistance was seen in the doxorubicin and cisplatin resistant variants of the A2780 ovarian carcinoma; the drug did not modulate sensitivity to doxorubicin in either parent or resistant lines. No cross-resistance to SDZ 62-434 was seen in a doxorubicin-resistant MCF-7 variant. Cytotoxicity was not due to non-specific membrane lysis. The potent PAF antagonist WEB 2086 did not modulate SDZ 62-434 cytotoxicity, indicating no role for PAF receptors. Precursor incorporation studies in A2780 cells showed that DNA synthesis was inhibited more effectively than protein synthesis while RNA synthesis was unaffected. SDZ 62-434 inhibited both bombesin and platelet-derived growth factor-induced DNA synthesis in quiescent Swiss 3T3 cells. This suggests a possible role for SDZ 62-434 as an inhibitor of signal transduction in cancer cells

Effect of urban vs. rural residence on the association between atopy and wheeze in Latin America: findings from a case-control analysis.

BACKGROUND: The association between atopy and asthma is attenuated in non-affluent populations, an effect that may be explained by childhood infections such as geohelminths. OBJECTIVE: To investigate the association between atopy and wheeze in schoolchildren living in urban and rural areas of Ecuador and examine the effects of geohelminths on this association. METHODS: We performed nested case-control studies among comparable populations of schoolchildren living in rural communities and urban neighbourhoods in the Province of Esmeraldas, Ecuador. We detected geohelminths in stool samples, measured recent wheeze and environmental exposures by parental questionnaire, and atopy by specific IgE (sIgE) and skin prick test (SPT) reactivity to aeroallergens. RESULTS: Atopy, particularly sIgE to house dust mite (HDM), was more strongly associated with recent wheeze in urban than rural schoolchildren: (urban, adj. OR 5.19, 95% CI 3.37-8.00, P < 0.0001; rural, adj. OR 1.81, 95%CI 1.09-2.99, P = 0.02; interaction, P < 0.001). The population fractions of wheeze attributable to atopy were approximately two-fold greater in urban schoolchildren: SPT to any allergen (urban 23.5% vs. rural 10.1%), SPT to HDM (urban 18.5% vs. rural 9.6%), and anti-HDM IgE (urban 26.5% vs. rural 10.5%), while anti-Ascaris IgE was related to wheeze in a high proportion of rural (49.7%) and urban (35.4%) children. The association between atopy and recent wheeze was attenuated by markers of geohelminth infections. CONCLUSIONS: Our data suggest that urban residence modifies the association between HDM atopy and recent wheeze, and this effect is explained partly by geohelminth infections

Should Marketing be Cross-Functional? : Conceptual Development and International Empirical Evidence

While it has frequently been stated that decisions on marketing activities should be made cross-functionally, there is no empirical evidence that shows benefits of performing marketing activities in this way. This paper examines the link between the cross-functional dispersion of influence on marketing activities and performance at the SBU level and considers dynamism of the market which may moderate the strength of this relationship. Using data from a cross-national study in three industry sectors, the authors find that cross-functional dispersion of influence on marketing activities increases the performance of the SBU. They also find that the relationship between the cross-functional dispersion of influence on marketing activities is negatively influenced by dynamism of the market. This research thus provides empirical evidence for the positive performance implications of cross-functional interaction in the context of marketing activities