Lack Of Segregation Research Articles

A network approach to cell formation in cellular manufacturing

SUMMARY Formation of machine cells often results in some intercellular movements between the cells. These movements cause lack of segregation among the cells. This is in conflict with the main objective of group technology which aims at independently operating cells. This paper presents a non-heuristic network approach to form manufacturing cells with minimum intercellular interactions. The machine-part matrix containing machining times is represented as a network which is subsequently partitioned by using a modified Gomory-Hu algorithm to find a minimum intercellular interaction. The modified algorithm improves the computational efficiency.

Genetic Analyses of Soybean Genotypes Resistant to Soybean Cyst Nematode Race 5

All soybean [Glycine max (L.) Merr.] cultivars currently grown in the USA are susceptible to soybean cyst nematode (SCN), Heterodera glycines Ichinohe, Race 5. Soybean plant introductions (PIs) with resistance to SCN Race 5 have been identified, but there is very little information on their genetic analyses for resistance. Our objectives were to determine inheritance of resistance in three PIs for reaction to SCN Race 5, and to evaluate five resistant PIs for their genetic relationship to SCN resistance. The F2 plants and F3 families from nine different crosses among resistant (R) and susceptible (S) genotypes were evaluated in the greenhouse. Each seedling was inoculated with about 1000 eggs and juveniles of SCN Race 5. Plant roots were washed after 30 d and white females enumerated. Based on the index of parasitism (IP) F2 plants and F3 progenies were categorized as resistant, susceptible, or segregating. The chisquare test was applied to determine goodness of fit between observed and expected genetic ratios. The segregation data from crosses ‘Peking’ (R) ✕ PI 88788(S), PI 438489B(R) ✕ PI 88788(S), and PI 90763(R) ✕ ‘Forrest’(S) indicated that resistance in Peking and PI 90763 was conditioned by two recessive genes each, whereas PI 438489B had one recessive gene. Crosses between resistant parents, Peking with PI 90763, PI 404166, and PI 84751 have segregated for resistance indicating that genes in Peking compared to other parents are located at different loci. Lack of segregation in crosses of PI 90763(R) ✕ PI 404166(R), Peking(R) ✕ PI 438489B(R) and PI 90763(R) ✕ PI 438489B(R) indicated that the resistance in these parents was controlled by alleles at the same locus. These results showed that there was at least one gene for resistance different in Peking, PI 90763, and PI 404166. Intercrossing these sources of different genes for resistance to SCN Race 5 should result in germplasm with potentially higher levels of resistance. This information will assist breeders in selecting resistant sources to SCN Race 5 for cultivar development.

Radial particle size segregation in a fast fluidised bed

The possible existence of radial particle size segregation effects in a fast fluidised bed has been explored. Samples of solid material were captured from various points across the cross-section of the bed and analysed for small changes in average size, and the results suggest that coarse-particle enrichment in the wall region is evident under certain conditions. High velocities (6 – 9 m/s) appear to promote this effect, while at low velocity (2 m/s) no significant segregation was observed. This lack of segregation at lower velocity is consistent with the existence of clusters of the type proposed by Yerushalmi et al. in the lean core, and the data suggest that these clusters gradually give way to a population composed more of separate particles behaving as individuals as velocity is increased. An examination of possible segregation mechanisms suggests that a model describing solids exchange between the core and the wall region is capable of producing effects which are consistent with those observed here. A mechanism describing differential axial slip in the lean core is shown to be inappropriate on the basis of the directional effects predicted.

Sex and Year Comparisons of Lake Superior Pink Salmon ( Oncorhynchus Gorbuscha) Adipose Fins

The adipose fins of pink salmon ( Oncorhynchus gorbuscha Walbaum) from the Carp River, a southeastern Lake Superior tributary, are sexually dimorphic. The adipose fins of males are consistently longer than those of females for all sizes of fish measured, despite sex and year differences in fish size. Greater relative adipose fin size in males may help reduce caudal peduncle wear resulting from agonistic interactions among competing males on the spawning grounds. Differences in relative adipose fin size between years were not found, consistent with the lack of segregation between even- and odd-year stocks which characterizes Great Lakes populations. Adipose fin size increased in a positive allometric fashion with increasing fish length in both sexes. Compared to British Columbia pink salmon, adipose fin sizes are less distinct sexually but similarly variable. This finding holds promise for use as a technique for sexing older Great Lakes pinks externally, and hence may have management implications.

Effect of irradiation on phosphorus segregation

Phosphorus strongly segregated to the surface during irradiation of austenitic-type alloys in the temperature range 775–925 K. Much weaker but measurable radiation induced segregation of phosphorus occurred in a Ni + 0.03% P alloy. Irradiation under similar conditions produced no measurable phosphorus segregation in the ferritic HT-9 or Fe + 0.03% P alloy. The lack of segregation in the ferritic alloys was suggested to result from a weak point defect — impurity interaction in the bcc iron structure while a strong interaction was suggested for the fcc iron structure. The slow accumulation of radiation damage in bcc iron alloys is also consistent with a lack of observable segregation. The evidence strongly suggests a radiation induced mechanism but a radiation enhanced, thermally activated equilibrium segregation cannot be ruled out.

Allozymes and genetic variability in Medicago turbinata, M. truncatula, and their hybrids

The genetic variability in the diploid annual species (2n = 2x = 16) Medicago turbinata L. and M. truncatula Gaernt. was studied at three loci for the enzymes peroxidase, Prx1-1, and leucine-aminopeptidase, Lap1-1 and Lap1-2. Eight accessions of each species, including all the taxonomic forms were surveyed by starch gel electrophoresis. No variation was observed among plants within each accession. Among the M. turbinata forms, four alleles were observed at locus Lap1-2. No variation was detected for the other two loci studied. For the M. truncatula forms, four alleles were found for Prx1-1 and three alleles for Lap1-2. No variation was observed for locus Lap1-1. Form uncinata of M. truncatula, of uncertain taxonomic status, has at least one M. turbinata allele. Both species can be differentiated by their specific allozymes. In general, the alleles of the isozymic loci segregated in a Mendelian fashion in the expected ratios for monomeric enzymes. The presence of chlorophyll-deficient plants on some of the progenies involving different taxonomic forms of the species M. turbinata indicates the presence of isolation barriers between these forms. The lack of segregation at locus Lap1-1 in the tetraploidized interspecific hybrid proves its alloploid nature.

Sex and Politics—New Alignments, Old Issues

The relationship between sex and political behavior has been discussed only in passing in the political science literature, if it is discussed at all. There has been little evidence from the 1940s to the 1970s that gender plays a role in determining issue positions, candidate evaluations, or candidate preference, as a quick perusal of some well-read political science works would confirm.Berelson, Lazarsfeld and McPhee in Voting, the seminal work on opinion formation in a presidential campaign, discovered no relationship between vote preference and sex. The researchers did discover a difference in reported interest in the 1948 campaign between men and women early in the campaign, but even that difference faded as the election drew near.Campbell, Converse, Miller and Stokes in The American Voter make no mention of either the existence or non-existence of sex difference in policy or candidate preference. They focus instead on differences in turnout, involvement and efficacy. Although they suggest that at one time opinions about Prohibition may have separated men from women, the authors conclude, “In the current era, there is no reason to believe that women as women are differentially attracted to one of the political parties.”Pomper in Voters' Choice does find a relationship between sex and one issue dimension–the dimension of war and peace. But Pomper, Campbell and Berelson agree that any sex differences cannot, by definition, be long-lasting. Berelson cites the lack of differentiation in the way policies affect the sexes, the lack of differences in intergenerational transmission, and the lack of segregation between the sexes.

Sex and Politics—New Alignments, Old Issues

The relationship between sex and political behavior has been discussed only in passing in the political science literature, if it is discussed at all. There has been little evidence from the 1940s to the 1970s that gender plays a role in determining issue positions, candidate evaluations, or candidate preference, as a quick perusal of some well-read political science works would confirm.Berelson, Lazarsfeld and McPhee in Voting, the seminal work on opinion formation in a presidential campaign, discovered no relationship between vote preference and sex. The researchers did discover a difference in reported interest in the 1948 campaign between men and women early in the campaign, but even that difference faded as the election drew near.Campbell, Converse, Miller and Stokes in The American Voter make no mention of either the existence or non-existence of sex difference in policy or candidate preference. They focus instead on differences in turnout, involvement and efficacy. Although they suggest that at one time opinions about Prohibition may have separated men from women, the authors conclude, “In the current era, there is no reason to believe that women as women are differentially attracted to one of the political parties.”Pomper in Voters' Choice does find a relationship between sex and one issue dimension–the dimension of war and peace. But Pomper, Campbell and Berelson agree that any sex differences cannot, by definition, be long-lasting. Berelson cites the lack of differentiation in the way policies affect the sexes, the lack of differences in intergenerational transmission, and the lack of segregation between the sexes.

Sex and Politics—New Alignments, Old Issues

The relationship between sex and political behavior has been discussed only in passing in the political science literature, if it is discussed at all. There has been little evidence from the 1940s to the 1970s that gender plays a role in determining issue positions, candidate evaluations, or candidate preference, as a quick perusal of some well-read political science works would confirm.Berelson, Lazarsfeld and McPhee inVoting, the seminal work on opinion formation in a presidential campaign, discovered no relationship between vote preference and sex. The researchers did discover a difference in reported interest in the 1948 campaign between men and women early in the campaign, but even that difference faded as the election drew near.Campbell, Converse, Miller and Stokes inThe American Votermake no mention of either the existence or non-existence of sex difference in policy or candidate preference. They focus instead on differences in turnout, involvement and efficacy. Although they suggest that at one time opinions about Prohibition may have separated men from women, the authors conclude, “In the current era, there is no reason to believe that womenas womenare differentially attracted to one of the political parties.”Pomper inVoters' Choicedoes find a relationship between sex and one issue dimension–the dimension of war and peace. But Pomper, Campbell and Berelson agree that any sex differences cannot, by definition, be long-lasting. Berelson cites the lack of differentiation in the way policies affect the sexes, the lack of differences in intergenerational transmission, and the lack of segregation between the sexes.

Different cholinergic synapses converging onto neurons in Aplysia produce the same synaptic action

We have investigated neurons that receive inputs from more than one cholinergic interneuron, to see whether one cholinergic input can depolarize and the other hyperpolarize by virtue of activating different ACh receptors. We have examined synapses made in the abdominal ganglion of Aplysia californica by 3 cholinergic interneurons. Two of those interneurons have previously been shown to be cholinergic. Using both biochemical and pharmacological tests we have shown a third interneuron to be cholinergic. For 7 postsynaptic cells, we compared 6 new connections that we have identified from cholinergic interneurons, and 12 previously known connections. In each case we found that different cholinergic inputs onto any given cell produced the same synaptic action. This finding held even for L7, a cell known to have two types of ACh receptors. These data are consistent with the hypothesis that a postsynaptic cell does not segregate different types of ACh receptors. If generally true, this lack of segregation may help explain why a nervous system uses more than one neurotransmitter as well as why certain interneurons are needed in neural networks.

Genetic control of serine dehydratase and phosphoenolpyruvate carboxykinase in mice.

Inbred strains of mice were found to differ with regard to their endogenous activities of the liver enzyme serine dehydratase (SD) and phosphoenolpyruvate carboxykinase (PEPCK). The strain distribution patterns for the activity of each enzyme were identical. On feeding of high-protein diets or on fasting, the activities of both enzymes were induced in a concordant fashion which suggested the control of both enzymes by a single gene. Genetic analysis established that the induction of both enzymes on feeding of high-protein diets was controlled by a single gene (Sdr-1), whereas the induction of SD, but not of PEPCK, in fasting was controlled by different single gene (Sdr-2). The lack of segregation of the backcross generations with respect to PEPCK activities obtained on fasting precluded the establishment of any association of the response of PEPCK to fasting with either the Sdr-1 or Sdr-2 locus. The strain of mice (BALB/cJ) that had the ability to maximally induce both gluconeogenic enzymes under both dietary treatments failed to survive a fast as long as those strains with less ability to induce. This suggests that the ability to induce key enzymes in gluconeogenesis when food is unavailable is of little consequence with regard to their ability to produce essential nutrients necessary for survival.

THE CYTOGENETIC POSITION OFAVENA DAMASCENAAMONG THE DIPLOID OATS

The diploid oat Avena damascena was successfully crossed with the diploids A. prostrata and A. strigosa. Chromosome pairing in A. strigosa × A. damascena hybrid indicated that the two parental species differ by three translocations. This hybrid also was completely sterile. The greater affinity of A. damascena to A. prostrata than to A. strigosa could be concluded from the smaller number of multivalents and the partial fertility of the A. prostrata × A. damascena hybrid. Although the number of chromosome rearrangements between A. damascena and A. strigosa was compatible with those found between A. prostrata and these two species, a marked difference in the frequency of the various translocations was noted. Predominantly bivalent pairing characterized the A. prostrata × A. damascena amphidiploid. The lack of segregation of a marker gene in the F2indicated conspicuous preferential pairing in this amphidiploid. A comparison of the number of bivalents per cell in this and in other amphidiploids involving the strigosa-like species suggests that the A. damascena genome has a high potential for preferential pairing.

Cytoplasmic and nuclear mutations to chloramphenicol resistance in Aspergillus nidulans.

Two chloramphenicol resistance mutations out of 123 tested in Aspergillus nidulans are inherited extranuclearly as judged by transmissibility in heterokaryons, lack of segregation at meiosis, and independent segregation from all of the eight nuclear linkage groups. They do not recombine with each other. However, experiments in collaboration with G. Turner and R.T. Rowlands show that they do recombine with cytoplasmic mutations to oligomycin resistance (Rowlands and Turner, 1973) and cold-sensitivity (Waldron and Roberts, 1973). These cytoplasmic chloramphenicol resistance mutations are stable and do not affect growth or morphology on antibiotic-free media. Nuclear mutations to chloramphenicol resistance map at a minimum of three loci. At one of these loci, most, but not all, mutations lead pleiotropically to cycloheximide hypersensitivity, and most of these, but not all, also confer pleiotropic hypersensitivity to salicylhydroxamic acid.

Some aspects of mutation

The existence of an independent metabolism makes the response of freeliving organisms to mutagens more varied than the response of viruses. Materials which inactivate virus can be mutagenic for free-living organisms. Metabolic systems permit organisms to bypass the phenotypic effect of some mutations and may themselves create conditions favoring mutation. The evidence indicates that mutation can take place in the absence of DNA synthesis. A process of base exchange in DNA must account for this class of mutations. However, the lack of segregation following treatment with certain mutagens is not a sufficient argument for mutation in the absence of DNA synthesis and an attempt to develop alternate explanations for the lack of segregation is made. A hypothesis is developed to account for the importance of protein synthesis in the mutation process. The hypothesis assumes that conditions favoring protein synthesis cause the DNA to become “available” for replication and that this “available” stage is a necessary intermediate in DNA synthesis. The period leading to the production of this intermediate is critical for the mutation process as induced by ultraviolet light and by alkylating agents.