Showing papers by "York University published in 1973"

Effects of a realistic job preview on job acceptance, job attitudes, and job survival

Abstract: A field experiment was conducted in a telephone company to assess the effects of a realistic job preview vs an unrealistic (i.e., “traditional”) preview. Of 80 newly hired female telephone operators, those who saw a realistic job preview film subsequently had more realistic job expectations, fewer t

Finite and infinite cyclic extensions of free groups

Abstract: Using Stalling's characterization [11] of finitely generated (f. g.) groups with infinitely many ends, and subgroup theorems for generalized free products and HNN groups (see [9], [5], and [7]), we give (in Theorem 1) a n.a.s.c. for a f.g. group to be a finite extension of a free group. Specifically (using the terminology extension of and notation of [5]), a f.g. group G is a finite extension of a free group if and only if G is an HNN group where K is a tree product of a finite number of finite groups (the vertices of K), and each (associated) subgroup Li, Mi is a subgroup of a vertex of K.

Interactions among genes controlling sensitivity to radiation and alkylation in yeast.

Abstract: In the simple eucaryote Saccharomyces cerevisiae there are at least three phenotypically distinct classes of mutants sensitive to inactivation by radiations and alkylating agents: class I mutants are sensitive to ultraviolet light and nitrogen mustard (HN2); class II mutants are sensitive to X-rays and methylmethane sulphonate (MMS); and class III mutants are sensitive to all four of these agents. We have constructed doubly mutant strains of types (I, I), (I, II), (I, III), and (II, III) and have measured their sensitivity to UV, X-rays, HN2 and MMS in order to characterize the interactions of the various mutant gene pairs. Class (I, III) double mutants proved to be supersensitive to UV and HN2 and class (II, III) double mutants proved to be supersensitive to X-rays and MMS. All other double mutants showed little or no enhancement of sensitivity over their most sensitive single mutant parents. Mutants of class I are known to be defective in excision repair and our results are consistent with the idea that there exist at least two additional pathways for dark repair in yeast, one capable of repairing X-ray and MMS damage to DNA, and another, possibly analogous to post-replication repair in bacteria, that competes with the other two for damaged regions in DNA.

Dynamic Lot Size Models for Multi-Stage Assembly Systems

Abstract: A multi-stage assembly system is a special case of Veinott's general multi-facility system in that each facility may have any number of predecessors but at most a single successor. This paper presents two algorithms for computing optimal lot sizes in such systems with known time-varying demand. The first is a dynamic programming algorithm for which solution time increases exponentially with the number of time periods, but only linearly with the number of stages, irrespective of assembly structure. The second is a branch and bound algorithm intended for cases where the number of time periods is large but the structure is close to serial. Computational results are given and extensions considered.

The visible-airglow experiment on Atmosphere Explorer

Abstract: The visible-airglow experiment is an airglow photometer designed to measure various thermospheric emission features during the day and night both at low latitudes and in auroras. The photometer has two distinct optical channels, a high-sensitivity channel with a large field of view and a low-sensitivity channel with a narrow field of view to resolve small features. The system is protected by a combination attenuator and cathode back-biasing scheme which allows measurements of maximum sensitivity within a fraction of a second of viewing the sun. This experiment will be a part of the scientific payload on all three Atmosphere Explorer missions.

Polarization properties of lidar backscattering from clouds.

Abstract: The polarization properties of the backscattering of a lidar pulse from atmospheric clouds have been measured. A linearly polarized signal from a ruby laser at 694.3 nm is transmitted, and the scattering is simultaneously measured on a three-channel receiver that has polarizers oriented parallel, perpendicular, and at 45 degrees to the transmitted polarization. Substantial depolarizations (up to 0.5) are observed, and from the spatial variation of this depolarization the contribution of multiple scattering can be deduced.A wide variation in polarization properties is observed in different cloud types, and the results indicate that polarization signatures could be useful for cloud characterization and classification.

True and simulated superior oblique tendon sheath syndromes

Abstract: The following conclusions can be drawn from this discussion concerning the true and simulated superior oblique tendon sheath syndromes : 1. Apparently there is a higher incidence of the sheath syndrome in females than in males and a higher incidence of involvement of the right eye than in the left eye. 2. Approximately 10% of the 126 cases are bilateral. 3. The clinical features of the true sheath syndromes are simulated by anomalies other than a congenital short anterior sheath of the superior oblique tendon in at least 20% of the sheath syndrome cases. There is reason to believe that the incidence of the simulated sheath syndrome is higher than 20%. 4. The true sheath syndrome is due to a primary congenital structural anomaly involving the anterior sheath of the superior oblique tendon. 5. The simulated sheath syndrome is due to a congenital structural anomaly involving the posterior tendon or to an abnormal firm attachment of the sheath to the posterior tendon or both. Either a thick area in the posterior tendon or firm attachments of the sheath to the posterior tendon can offer some resistance to the forward movement of the tendon through the trochlea. The abnormal firm attachments of the sheath to the posterior tendon occurs probably more frequently than a thickened area in the posterior tendon. 6. A positive traction test in congenital cases, at the present time, can be considered pathognomonic for a true sheath syndrome. 7. Acquired and intermittent simulated sheath syndromes are of inflammatory origin. 8. An operation is not indicated in the absence of a disfiguring head tilt or a vertical tropia.

On the preferential abuse of heroin and amphetamine.

Abstract: Although most drug abusers have experienced a variety of psychotropic agents, many abusers experience a prolonged and distinct preference for a particular drug. To examine the relationship between drug preference and personality, preferential abusers of heroin and amphetamine were interviewed while

Will the real consumer-activist please stand up : an examination of consumers' opinions about marketing practices

Abstract: The topic of consumerism, while frequently discussed in the media, has only recently been addressed by formal market research [1, 4]. Are there groups of people with essentially similar attitudes toward business practices? How large are these groups, and do the relative strengths of their feelings about marketing practices vary from one group to the next? If a consumer activist group exists, what other feelings, predispositions, and behavior help differentiate that group from more passive, tolerant, or satisfied people? In November and December of 1970, a large consumer survey was completed at Purdue University by Pessemier, DeBruicker, and Hustad in which extensive activity and attitude measures were obtained for 912 husband and wife pairs. The sample was a representative demographic cross section of Lafayette, Indiana, an upscale midwestern industrial community. The analysis reported in this article is based upon the data provided by the 912 women in the survey. In addition to standard socioeconomic data, product usage rate data, and other traditional measures, the subjects provided detailed records of their attitudes and activities relating to six product categories, a wide range of media and communication elements, and an extensive set of topics which were less product-and-media specific. A detailed discussion of the design, the instruments employed, and the reliability of the data is provided in [5]. The data most central to the questions raised by this article were obtained via a series of 115 semantic differentially scaled variables spanning many dimensions of consumers' feelings toward business and marketing practices. Observations on literally hundreds of supplementary variables were obtained. Categories and listings of these supplementary data will be introduced as this analysis proceeds.

Body composition changes in children receiving human growth hormone.

Abstract: Skinfold thickness was found to decrease during the first 6–10 wk and then remain constant when human growth hormone therapy was begun in 34 growth hormone-deficient children. Linear growth increased at a constant rate during the first 6 mo. Two children, who routinely received their injection in the same arm at the same site, developed a localized area of markedly diminished subcutaneous fat at the injection site, Height, weight, total-body potassium, and triceps skinfold thickness were measured at 2-mo intervals in nine children receiving human growth hormone. Total-body potassium was measured with the 54-Nal detector whole-body counter of the Brookhaven National Laboratory. The study extended over a period of 20 consecutive mo. Triceps skinfold thickness rapidly decreased during the initiation of therapy with growth hormone, and returned to pretreatment values during a 5-mo control period when therapy was temporarily discontinued. Rate of weight gain was most rapid during this 5-mo control period and was reduced during two periods when growth hormone was being administered. Total body potassium and height increased very little during the control period when weight gain was greatest, and both increased rapidly during the two periods of growth hormone treatment. The data show clearly the initial changes in body fat and lean tissue that occur when human growth hormone is administered to children with growth deficiency.

Effects of personal background and training on work values of the hard-core unemployed.

Abstract: This study described how work values of 110 disadvantaged persons differ from those of 180 unskilled and semiskilled employees, identified biographical correlates of work values, and examined changes in work values following training. When compared with regular employees, hard-core trainees placed less emphasis on the tendency to keep active on the job, taking pride in their work, and subscribing to the traditional Protestant Ethic, but placed more emphasis on making money on the job. Significant relationships were found between background characteristics and work values of the hard core. Changes in work values of disadvantaged subjects after 8 weeks of training did not differ from those of 2 52 controlled subjects (insurance agents and college students). Persons classified as disadvantaged or hard core represent a subculture of our society with an indigenous life style and value system. One aspect of this value system that is of particular interest to social scientists is the concept of work values-—an individual's attitude toward work in general rather than his feelings about a specific job. Many authors have speculated about the development of attitudes of the hard core, but they have presented few data to support their conclusions. From a series of intensive interviews of 600 middle- and working-class families in Chicago, Davis (1946) identified three factors that may produce the behavior and set of values characteristic of the ghetto subculture. First, the necessity for survival forces the child of the lower-class family to seek immediate gratification of the most basic physical needs (food, clothing, and shelter), and it inhibits his striving for less urgent goals. Second, Davis argued that when a person becomes

“Lotka's law in the humanities?”

Abstract: It is stressed that Lotka's Law was originally only applicable in physical science, specifically chemistry and physics. The more recent general application of Lotka's Law in non-physical science, without appropriate new tests of validity, is bemoaned. A recent test in the humanities is discussed, showing that Lotka's Law does apply reasonably in that speciality. A plea is made for more “spot checks” of so called general “Laws,” which were determined using specific subject samples—not only for Lotka's Law, which is used here as an example, but in all such “laws” applied in information science, in general.

Odd Nitrogen in the Atmosphere

Abstract: Sources and sinks for atmospheric odd nitrogen are discussed and detailed calculations are presented for the altitude range 0–80 km. The mixing ratio of odd nitrogen is approximately 2×10−9 throughout the troposphere and increases in the stratosphere to a value of order 2×10−8 at 40 km. The dominant atmospheric forms of odd nitrogen are HNO3, NO2 and NO. Nitric acid is the major form below 25 km. Nitric oxide is the most abundant constituent during the day and at night is efficiently converted to NO2 below 65 km. Possible modification of stratospheric NOx by supersonic aircraft is discussed and it is concluded that the consequences may be detectable if the globally averaged source of NO from stratospheric aviation should exceed 4×107 molecules cm−2 sec−1.

A study of bicomponent coextrusion of molten polymers

Abstract: An experimental study has been carried out of coextruding polystyrene with lowdensity polyethylene and polystyrene with high-density polyethylene, using both slit and circular dies. Two melt streams were separately fed to the die entrance and forced to flow side by side through a die. When using the slit die, wall normal stresses were measured with three melt pressure transducers flush-mounted on each of the rectangle's long sides, directly opposite each other. When using the capillary die, three different capillary length-to-diameter (L/D) ratios were employed: 4, 11, and 18. Wall normal stresses were measured for dies having L/D ratioes of 11 and 18 only. The measurements of wall normal stresses permitted one to determine the pressure gradient, and hence the viscous property. For each set of extrusion conditions (L/D ratio, flow rate, and component ratio), extrudate samples were collected. These were later carefully cross sectioned and photographed in order to examine the shape of the interface between the two components. At the phase interface of the polystyrene/low-density polyethylene system, it has been observed that the polystyrene, which is more viscous and yet less elastic than the low-density polyethylene, has a convex surface. However, at the phase interface of the polystyrene/high-density polyethylene system, the high-density polyethylene, which is more viscous and also more elastic than polystyrene, is seen to be convex. This then appears to indicate that the viscosity ratio of two components is primarily responsible for the final shape of the interface.

Modeling Supermarket Product Selection

Abstract: Supermarket chains appraise more than 8,000 new product offerings per year. This article models the choice process to reduce management appraisal time and obtain a greater understanding of the vari...

The development, structure and function of modified synaptonemal complexes in mosquito oocytes.

Abstract: The nucleus of the maturing oocytes expands to a large thin body of 400×140×3 μm but the chromosomes remain together in a small sphere, 15 μm in diameter. In Aedes aegypti this sphere becomes surrounded by one to several layers of polycomplexes, annulated polycomplexes, and related annulated pseudomembranes. Just prior to egg laying the expanded nucleus disintegrates while the sphere of chromosomes is surrounded by several layers of membranes. In Culex pipiens the elements which normally connect the lateral elements of the synaptonemal complexes become extended so that all bivalents become interconnected by a framework of pseudomembranes. The continuity between the modified synaptonemal complexes and various membranes associated with the karyosphere suggest that a relationship exists, by origin or by specialization, between the synaptic structures and nuclear envelope.

Inhibition of enzymes which interact with citrate by (--)hydroxycitrate and 1,2,3,-tricarboxybenzene.

Abstract: The effects of two citrate analogues, (—)hydroxycitrate and 1,2,3-tricarboxybenzene, were studied using rat liver enzymes which interact with citrate. The most pronounced effect of 1,2,3-tricarboxybenzene was inhibition of acetyl-CoA carboxylase (Ki 20 μM). It also inhibited the mitochondrial citrate transporter (50% inhibition at 3 mM), but was not a substrate for this transporter. ATP-citrate lyase was markedly inhibited by both free (—)hydroxycitrate (Ki 8 μM) and (—)hydroxycitrate lactone (Ki 50 to 100 μM). Acetyl-CoA carboxylase was activated by both the forms of (—)hydroxycitrate (Ka 0.7 mM and 1.6 mM, respectively). (—)Hydroxycitrate is a substrate for the mitochondrial citrate transporter, but its rate of transport is less than 10% of that of citrate. Other citrate metabolizing enzymes also were inhibited by 1,2,3-tricarboxybenzene and (—)hydroxycitrate but much higher concentrations were required.

Studies of converging flows of viscoelastic polymeric melts. I. Stress‐birefringent measurements in the entrance region of a sharp‐edged slit die

Abstract: Measurements were taken of flow birefringence of viscoelastic polymeric melts in the upstream reservoir and in the entrance region. Materials investigated were polypropylene, high-density polyethylene, and polystyrene. Stress-birefringent patterns, both isochromatics and isoclinics, were formed when a beam of polarized light was sent through a transparent glass cell which consists of a large reservoir and slit die section. Pictures were taken of stress-birefringent patterns, which were later used to obtain quantitative information on the stress distributions of flowing polymeric melts, with the aid of stress optical laws. Also measured were wall normal stresses in the fully developed region, downstream in the thin slit section, which then permitted us to directly determine the stress optical coefficients of the materials tested.

Power, fresh water, and food from cold, deep sea water.

Abstract: Many times more solar heat energy accumulates in the vast volume of warm tropic seas than that produced by all of our power plants. The looming energy crisis causes a renewal of interest in utilizing this stored solar heat to give, in addition to electric power, vast quantities of fresh water. Warm surface water, when evaporated, generates steam, to power a turbine, then fresh water when the steam is condensed by the cold water. A great increase in revenues over that from power and fresh water is shown by a substantial mariculture pilot plant. Deep sea water contains large quantities of nutrients. These feed algae which feed shellfish, ultimately shrimps and lobsters, in shallow ponds. Wastes grow seaweed of value; and combined revenues from desalination, power generation, and mariculture will give substantial profit.

The Kambarin Beriberi: the formation of a specialized group of Hausa Kola traders in the nineteenth century

Abstract: The origins of the Kambarin Beriberi and their conscious development of a corporate identity provides a valuable insight into the emergence of a Muslim mercantile class in the northern savanna region of Africa. Theoretical studies by Abner Cohen and others have drawn attention to the maintenance of economic and social diasporas which have permitted the creation of commercial monopolies, but the explanation that these diasporas have been ‘ethnic’ organizations has obscured a fundamental feature of their historical development. Not all Hausa have participated in the kola trade, nor have the majority of professional merchants resided along the commercial avenues outside of the Hausa homeland. As the case of the Kambarin Beriberi well documents, the origins of many traders who became identified as Hausa were as immigrants from other parts of Africa, and any understanding of the formation of commercial diasporas must consider the possible distinction between the various components of a trading system. Only then can a fuller understanding of the interaction between the different commercial segments be reached. The diasporas which Cohen has documented for the Hausa, and which others have analysed for the several Mande networks, represent but one level of commercial cooperation in the continental trade patterns of Africa. The fusion of such disparate groups as the Kambarin Beriberi and other Hausa merchants into a confederation of traders with common interests remains an important aspect of commercial development which has not been fully explored.