Showing papers by "North Carolina State University published in 1975"

The Farm-Retail Price Spread in a Competitive Food Industry

Abstract: Consistency with market equilibrium places constraints on the pricing policies of food marketing firms in a competitive industry. This paper examines the implications of simultaneous equilibrium in three related markets: retail food, farm output, and marketing services. From equations representing the demand and supply sides of each market, elasticities are generated which show how the farm‐retail price spread changes when retail food demand, farm product supply, or the supply function of marketing services shifts. Implications for the viability of simple markup pricing rules and the determinants of the farmer's share of the food dollar are discussed.

Distribution and Persistence of Staphylococcus and Micrococcus Species and Other Aerobic Bacteria on Human Skin

Abstract: The distribution of Staphylococcus and Micrococcus species and associated coryneform bacteria, Acinetobacter, Klebsiella, Enterobacter, Bacillus, and Streptomyces on skin was determined during October 1971 from samples collected on persons living in North Carolina and New Jersey. Persistence of these organisms on skin was estimated in temporal studies conducted during the period from June 1971 to June 1972 on persons living in North Carolina. Staphylococci and coryneforms were the most predominant and persistent bacteria isolated from the nares and axillae. Staphylococci, coryneforms, micrococci, and Bacillus were the most predominant and persistent bacteria isolated from the head, legs, and arms. Acinetobacters were most frequently isolated during the warmer months of the years. Staphylococcus aureus and S. epidermidis were the most predominant and persistent staphylococci isolated from the nares, whereas S. epidermidis and S. hominis were the most predominant and persistent staphylococci isolated from the axillae, head, legs, and arms. S. capitis was often isolated from the head and arms and S. haemolyticus was often isolated from the head, legs, and arms. S. simulans, S. xylosus, S. cohnii, S. saprophyticus, S. warneri, and an unclassified coagulase-positive species were only occasionally isolated from skin. Micrococcus luteus was the most predominant and persistent Micrococcus isolated from skin and preferred regions of the head, legs, and arms. M. varians was the second most frequent Micrococcus isolated. M. lylae, M. sedentarius, M. roseus, M. kristinae, and M. nishinomiyaensis were only occasionally isolated from skin. M. lylae was most frequently isolated during the colder months of the years.

An algorithm for a selective nearest neighbor decision rule (Corresp.)

Abstract: A procedure is introduced to approximate nearest neighbor (INN) decision boundaries. The algorithm produces a selective subset of the original data so that 1) the subset is consistent, 2) the distance between any sample and its nearest selective neighbor is less than the distance from the sample to any sample of the other class, and 3) the subset is the smallest possible.

Intensity and reverberation as factors in the auditory perception of egocentric distance

Abstract: Both auditory intensity and reverberation have previously been shown to be sufficient to produce systematically varying judgments of perceived distance when several values of the variable are presented repeatedly to the same observer. Such studies do not, however, indicate clearly whether these cues are functioning in an absolute or in a relative manner. An absolute cue to auditory distance would require that two groups presented with different values of the variable in question should report different values of perceived distance. Two experiments are reported in which intensity variation and reverberation are examined. The results showed that auditory intensity differences over a range of 20 dB did not serve as an absolute cue to auditory distance, but could serve as a strong cue to changes in such distance. A comparison of data obtained in a normally reverberatory setting (Experiment 1) and an anechoic chamber (Experiment 2) indicated that the state of reverberation could serve as an absolute cue, with greater reverberation being associated with greater perceived distances. Some of the results were discussed in terms of the possibility that the specific distance tendency (a concept developed to handle some phenomena in visual space perception) might have applicability to the study of auditory perceived distance as well.

Microbial Inhibition by an Isolate of Pediococcus from Cucumber Brines

Abstract: We reported earlier that Pediococcus cerevisiae FBB-61 inhibited Lactobacillus plantarum FBB-67 in mixed species inoculation used for the fermentation of brined cucumbers. Herein, 16 isolates of the Pediococcus genus from various sources were tested for inhibitory activity against L. plantarum and other microorganisms by a seeded-agar screening technique. Only two of the 16 isolates gave consistent and distinctive zones of inhibition, and both were isolated from fermenting cucumber brines on separate occasions. These two isolates did not inhibit each other but did inhibit the other 14 Pediococcus isolates in addition to L. plantarum. They also inhibited several other gram-positive bacteria, but not four species each of gram-negative bacteria and yeasts tested. Inoculation of cucumber juice broth with P. cerevisiae FBB-61 and L. plantarum WSO resulted in a drastic reduction in the plate count of L. plantarum WSO during day 1, but counts increased rapidly thereafter. Consequently, acid production by L. plantarum WSO was delayed. Noninhibitory isolates of Pediococcus had no appreciable effect on growth and acid production by L. plantarum WSO.

Interaction of Methylenedioxyphenyl (1,3-Benzodioxole) Compounds with Enzymes and Their Effects on Mammals

Abstract: (1975). Interaction of Methylenedioxyphenyl (1,3-Benzodioxole) Compounds with Enzymes and Their Effects on Mammals. Drug Metabolism Reviews: Vol. 3, No. 1, pp. 231-301.

Repair and enumeration of injured coliforms by a plating procedure.

Abstract: Surface plating of coliforms on Trypticase soy agar, followed by 1 to 2 h of incubation at 25 C and subsequent overlay with violet red bile agar, was found to be a useful method for the repair and enumeration of coliforms injured by freezing.

Soils of the Tropics and the World Food Crisis

Abstract: The properties and potential of soils of the tropics are poorly understood The old idea that laterite is formed when tropical soils are cleared is true of only a small proportion of the area In most features, soils in the tropics are similar or equivalent to soils in the temperate regions Specifically, soil organic matter contents, commonly believed to be low in the tropics, are essentially similar to those of the temperate regions While the basic concepts about physical and chemical behavior developed in the nonglaciated temperate regions are directly applicable to the tropics, the development of soil management practices for sustained food production involves different strategies because of environmental and economic constraints A major distinction is made between the development of high base status and low base status soils With the former, soil management practices should be aimed at maximizing the potential of high-yielding varieties and improving intercropping systems with relatively intensive fertilizer inputs With the low base status soils of the vast savanna and jungle areas energyrelated inputs should be optimized by (i) selecting of crop varieties and species more tolerant to nutritional deficiencies or toxicities, (ii) applying fertilizers at lower rates than those recommended by classic marginal analysis, and (iii) increasing the efficiency of applied fertilizers in such soils

Nephrotoxicity of Dietary Ochratoxin A in Broiler Chikens

Abstract: Graded doses of pure ochratoxin A (0, 0.5, 1.0, 2.0, 4.0, and 8.0 μg of toxin per g of feed) were incorporated into a commercial diet which was fed to chicks from 1 day to 3 weeks of age, at which time the experiments were terminated. Growth was inhibited at 2.0, 4.0, and 8.0 μg/g, whereas the kidneys were enlarged at doses of 1.0 μg/g and above. Renal function as measured by clearance of phenol red was decreased 15 and 31% by doses of 4.0 and 8.0 μg/g, respectively. Uric acid was increased 38 and 48% over the control values by doses of 4.0 and 8.0 μg/g, respectively. The plasma electrolytes Na, Cl, Ca, and K were measured; however, only K was significantly (P < 0.05) altered, showing a decrease at doses of 4.0 and 8.0 μg/g. The percentage dry weight of the kidneys decreased significantly at dose levels of 4.0 and 8.0 μg/g, indicative of edema. Histological examination of kidney sections gave the impression of edema and some tubular necrosis. Pathological changes were observed at all dose levels. These data demonstrate that ochratoxin A is a severe nephrotoxin in young broiler chickens.

Detection of Lactobacillus acidophilus in Feces of Humans, Pigs, and Chickens

Abstract: Lactobacilli in fecal material from humans, pigs, and chickens were enumerated on lactobacillus selective agar (LBS). In all samples, higher numbers of lactobacilli were detected when plates were incubated in a system flushed with CO2 rather than in air. Much higher numbers of bacteria from human feces were detected when the LBS agar plates were incubated anaerobically in a hydrogen-carbon dioxide atmosphere (GasPak) than when incubated in CO2. The bacteria from human feces isolated on LBS agar incubated anaerobically were predominately bifidobacteria. Cultures from all three sources isolated on LBS agar incubated under CO2 were lactobacilli, including Lactobacillus acidophilus. Differences were observed in biochemical characteristics of some of the L. acidophilus isolated from all three sources. Guanine plus cytosine base ratios of deoxyribonucleic acid isolated from L. acidophilus cultures from humans were lower, in most cases, than those from pigs and chickens.

Population size and selection intensity effects on long-term selection response in mice.

Abstract: Long-term response to within full-sib family selection for increased postweaning gain was evaluated in lines having different effective population sizes ( Ne ) and selection intensities ( i ). Line designations were I4(4), I8(2), I16(2), M4(4), M8(2) and M16(2), where I and M indicate selection of the top 50% and 25%, respectively; 4, 8 and 16 represent the number of parental pairs per replicate and number of replicates is given in parentheses. Realized within full-sib family heritabilities ( hR2 ) in the first phase of selection (0-14 generations) were larger in 16-pair lines than in 4- and 8-pair lines. In the second phase of selection (>14 generations), hR2 declined significantly (P<.01) in all lines, and only the I16 and M16 lines had hR2 values significantly (P<.01) greater than zero. Realized genetic correlations involving number born, 12-day litter weight, weaning weight and six-week weight tended to decline in the second phase of selection. The I16, M16 and control (C16) replicates were crossed in all combinations at generation 14. Crosses were then selected within litters for high postweaning gain. The hR2 values in the crossbred lines were all larger than those in the second selection phase for M16-1, M16-2 and I16-1, but not for I16-2. Within each Ne level, total response was significantly (P<.01) less for I lines compared with M lines. Total response increased as Ne increased, within each level of i . Relatively small differences in realized i values among Ne lines could not account for this result. The difference in total response among the Ne lines at a given selection intensity may be due to inbreeding depression and a combination of interactions involving "drift" and selection. By crossing replicates of the M lines with the C16 control, the effects of inbreeding depression were removed. Inbreeding depression and genetic drift, as defined herein, were equally important in accounting for differences among Ne lines in total response.

Potential for Converting Wood into Plastics: Chemicals from wood may regain importance as the cost of petroleum continues to rise.

Abstract: The conversion of wood into chemicals for the production of most of our synthetic plastics, fibers, and rubbers is technically feasible. With refinements in technology a large integrated plant utilizing all components of the wood for production of ethanol (to be further processed to ethylene and butadiene), phenols and furfural would be approaching economic feasibility as well at current petrochemical prices. If crude oil prices continue to climb at a faster rate than wood costs, the economic feasibility of chemicals for polymers from wood would become certain. Although technical feasibility has not been established, synthetic oils from liquefaction of wood might serve as feedstocks for cracking to chemicals in the same way that crude oil is presently used. The fulfillment of all our polymer needs from wood as a raw material should not place an impossible burden on our wood supply, but might actually improve the availability of wood for lumber, plywood and pulp by providing a use for less valuable wood which would allow reforestation and improved forest management.

Genetic structure of races of Heterodera glycines and inheritance of ability to reproduce on resistant soybeans.

Abstract: Four field populations of Heterodera glycines tested for ability to reproduce on three host differentials were each classified into one of the recognized races. A fifth population represented a new race. Genetic analysis indicated that the designated races are actually field populations that differ from each other primarily in the frequencies of three groups of genes (genes for parasitism) that act quantitatively and control the ability of the nematode to reproduce on resistant P.I. 88788, Pickett, and P.I. 90763 soybeans. Populations of race-3 have none of these genes for parasitism, or they have some in low frequency that results in an index of parasitism of less than 10 on any one of the resistant soybeans. Race- 1 has a high frequency of one group of genes that enable it to reproduce on P.I. 88788. Race-2 has two groups of genes for parasitism in high frequency; one for P.I. 88788, and one for Pickett. Based on these findings, it was assumed that race-4 has three groups of genes for parasitism; one for P.I. 88788, one for Pickett, and one for P.I. 90763. Additional races may be recognized when new genes are identified, or when new gene combinations are discovered. The ability to reproduce on P. I. 88788 is inherited independently from the ability to reproduce on Pickett. Although the genetic structure of field populations does not provide a solid foundation for race designation, recognizing races under the present system may be useful when it clearly characterizes the behavior of field populations. Race designations, however, should be regarded as provisional since gene frequencies change with time in response to selection forces and, therefore, the race status of a population may change accordingly. Key words: index of parasitism, genes for parasitism, cyst nematodes.

Nitrate Uptake and Assimilation by Wheat Seedlings during Initial Exposure to Nitrate.

Abstract: Nitrate uptake, reduction, and translocation were examined in intact, 14-day-old, nitrogen-depleted wheat ( Triticum vulgare var. Knox) seedlings during a 9-hour exposure to 0.2 mm Ca (NO 3 ) 2 . The nitrate uptake rate was low during the initial 3-hour period, increased during the 3- to 6-hour period, and then declined. By the 3rd hour, 14% of the absorbed nitrate had been reduced, and this increased to 36% by the 9th hour. Shoots accumulated reduced 15 N more rapidly than roots and the ratio of reduced 15 N to 15 N-nitrate was higher in the shoots. A significant proportion of the total reduction occurred in the root system under these experimental conditions. Accumulation of 15 N in ethanol-insoluble forms was evident in both roots and shoots by the 3rd hour and, after 4.5 hours, increased more rapidly in shoots than in roots. An experiment in which a 3-hour exposure to 0.2 mm Ca ( 15 NO 3 ) 2 was followed by a 12-hour exposure to 0.2 mm Ca ( 14 NO 3 ) 2 revealed a half-time of depletion of root nitrate of about 2.5 hours. A large proportion of this depletion, however, was due to loss of 15 N-nitrate to the ambient 14 N-nitrate solution. The remaining pool of 15 N-nitrate was only slowly available for reduction. Total 15 N translocation to the shoot was relatively efficient during the first 3 hours after transfer to Ca ( 14 NO 3 ) 2 but it essentially ceased after that time in spite of significant pools of 15 N-nitrate and α-amino- 15 N remaining in the root tissue.

Equilibrium Quantity and Timing of Mexican Vegetable Exports

Abstract: Mexico has recently expanded its exports of tomatoes, peppers, and cucumbers to the United States. In order to evaluate possibilities for further expansion, a linear programming production model for specific regions in Mexico was constructed and tested. Various equilibrium situations were analyzed to appraise possible future trends. Special features of the model were the inclusion of risk, demand functions for all crops, and allowance for both competitive and monopolistic supply structures. It was concluded that rising wage rates and tighter supply controls would halt Mexico's expansion of export winter vegetables.