Showing papers by "University of Massachusetts Amherst published in 1972"

Theory of Electron-Molecule Collisions by Frame Transformations

Abstract: Laboratory-frame and body-frame treatments are combined using the $l$-uncoupling transformation which had served to interpret the absorption spectrum of ${\mathrm{H}}_{2}$. Application of a phase-amplitude procedure converts the Schr\"odinger equation to a Volterra-type integral form, which reduces to a Born-like approximation when the long-range interactions are weak. Attention is directed to features of low-energy collisions that must be considered by a realistic theory. This paper develops a formalism that can take advantage of different simplifying factors in different ranges of the electron-molecule distance. Detailed developments and applications are deferred.

Repellent Odour in Aphids

Abstract: WE have found that Myzus persicae aphids are repelled by the odour of droplets released from the cornicles and squashed aphids of the same species.

A multivariate dental sexing technique

Abstract: This paper presents a method of sexing skeletal remains using dental measurements. A base sample from a population is sexed with reference to the postcranial skeleton and the dental measurements (buccal-lingual and mesial-distal diameters) are analyzed by the discriminant function technique. A linear function is derived, which will classify by sex the remaining portion of the population.

A cytological study of the ovary of Rhodnius prolixus. I. The ontogeny of the follicular epithelium.

Abstract: The relatively undifferentiated cells comprising the prefollicular epithelium of the fourth and fifth instar of the reduvid bug Rhodninus prolixus are flattened and contain the regularly occurring organelles, lipid droplets, and aggregates of glycogen-like particles These cells transform into the adult prefollicular tissue During vitellogenesis there is a gradual shortening of the cells of the follicular epithelium and an increase in the size of the intercellular space between them and between follicle cells and oocyte The follicle cells are binucleate, contain numerous microtubules, rough endoplasmic reticulum, many free and aggregate ribosomes, and Golgi complexes They are associated with each other by gap junctions Only the follicle cells on the lateral aspects of the oocyte exhibit the development of large extracellular spaces while those at the apical end, that produces the cap, remain tall and closely apposed to each other during vitellogenesis The normal morphology of the follicle cells over various areas of the oocyte suggests that shape and/or volume changes of these cell may be important in regulating the access of yolk proteins to the colemma Subsequent to vitellogenesis the follicle cells become cuboidal and once again become closely apposed to each other They contain much rough endoplasmic reticulum and produce the secondary coat

2‐Alkylcyclobutanones from the radiolysis of triglycerides

Abstract: A cyclic compound was isolated from the radiolytic products of each of the simple triglycerides containing C6, C8, C10, C12, C14, C16 and C18 fatty acids. In each case the compound was identified as the 2-alkylcyclobutanone of the same carbon number as the precursor fatty acid. A mechanism is proposed for the production of these compounds which involves the formation of a six-membered ring intermediate, cyclization and cleavage at the acyl-oxy bond.

Multiple Forms of Pseudomonas multivorans Glucose-6-Phosphate and 6-Phosphogluconate Dehydrogenases: Differences in Size, Pyridine Nucleotide Specificity, and Susceptibility to Inhibition by Adenosine 5′-Triphosphate

Abstract: Two major species of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) differing in size, pyridine nucleotide specificity, and susceptibility to inhibition by adenosine 5′-triphosphate (ATP) were detected in extracts of Pseudomonas multivorans (which has recently been shown to be synonymous with the species Pseudomonas cepacia) ATCC 17616. The large species (molecular weight ca. 230,000) was active with nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP) and was markedly inhibited by ATP, which decreased its affinity for glucose-6-phosphate and for pyridine nucleotides. This form of the enzyme exhibited homotropic effects for glucose-6-phosphate. The small species (molecular weight ca. 96,000) was active with NADP but not with NAD, was not inhibited by ATP, and exhibited no homotropic effects for glucose-6-phosphate. Under certain conditions multiplicity of 6-phosphogluconate dehydrogenase (EC 1.1.1.43) activities was also noted. One form of the enzyme (80,000 molecular weight) was active with either NAD or NADP and was inhibited by ATP, which decreased its affinity for 6-phosphogluconate. The other form (120,000 molecular weight) was highly specific for NADP and was not susceptible to inhibition by ATP. Neither form of the enzyme exhibited homotropic effects for 6-phosphogluconate. The possible relationships between the different species of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase are discussed.

Percolation of Code to Enhance Parallel Dispatching and Execution

Abstract: This note investigates the increase in parallel execution rate as a function of the size of an instruction dispatch stack with lookahead hardware. Under the constraint that instructions are not dispatched until all preceding conditional branches are resolved, stack sizes as small as 2 or 4 achieve most of the parallelism that a hypothetically infinite stack would.

Avian scale development. I. Histogenesis and morphogenesis of the epidermis and dermis during formation of the scale ridge

Abstract: Scale development in the chick embryo can be considered as consisting of two major phases. First, a definitive scale ridge is formed from a simple two-layered epidermis. This phase consists of five stages: preplacode, placode, asymmetrical placode, hump stage, and definitive scale ridge. The second phase involves the elongation of the definitive scale ridge to give rise to the overlapping scales of the adult bird. During elongation a new (inner) epidermal surface is formed, which is histologically less differentiated than the outer epidermal surface. A timed-sequence study has shown that the placode gives rise mainly to the outer epidermal surface of the definitive scale ridge, while the inter-placode region becomes the thinner epidermis at the scale apex.

Non-Hermitian Hamiltonians, Decaying States, and Perturbation Theory

Abstract: The conventional time-independent perturbation theory and projection-operator techniques are generalized to systems propagating under the influence of an effective non-Hermitian Hamiltonian, e.g., an optical-model potential. The mathematical complications which can arise due to lack of orthogonality and completeness for the eigenstates of such a Hamiltonian are discussed on an elementary level. Examples of the various techniques involved are taken from considerations of models for exotic atoms and cascade processes.

Instigation to Goodness: The Role of Social Norms and Interpersonal Influence

Abstract: Norms are only one of a variety of determinants of prosocial behavior. The distinction between knowing and personally accepting a norm is stressed. Two specific norms of prosocial behavior are discussed: the norm of reciprocity, and the norm of social responsibility. Reciprocity seems to guide both return of benefits and retaliation of harm. However, the intent attributed to another, the degree of his self sacrifice, and other conditions affect the degree of reciprocity. The evidence that a norm of responsibility guides helping behavior is less convincing. In emergencies (and probably other situations), not only normative (generalized) expectations, but also (specific) expectations communicated by other people who are present and rules applicable to the specific situation seem to greatly affect behavior. This may be due both to people's concern about others' reactions to them and to a social definition of reality.

Spectroscopy and structure of pentacoordinated molecules

Abstract: Many proposed reaction mechanisms involve a transitory pentacoordinate intermediate. For example, the change in optical activity accompanying bimolecular displacement at tetrahedral carbon has reasonably been explained as resulting from the formation of a trigonal-bipyramidal transient with the entering and leaving groups occupying apical positions.1 Also reasonable are mechanisms advanced to account for relative rates and products formed in the hydrolysis of phosphate esters' or displacements in phosphonium' systems. Certain hypotheses4 governing the stability of the transitory trigonal-bipyramidal species are applied, and a specific intramolecular exchange process is stipulated to occur in order to account for some of the experimental information.' Mechanisms proposed to proceed via pentacoordinate species involving transition metal compounds5,6 are more speculative, whether they be dissociative (involving octahedral structures) or bimolecular (involving four-coordinate geometries).

The effects of fixed ratio sample requirements on matching to sample in the pigeon

Abstract: Eight Carneaux pigeons were trained on a zero-delay matching-to-sample task in which 1, 10, 20, or 40 responses were required to the sample before presentation of the comparison stimuli. The results indicated increased speed of acquisition as a direct function of the FR sample requirement. In addition, increasing the number of required sample responses facilitated performance in both delayed matching and in a transfer task in which novel stimuli were introduced. These results are discussed in terms of the strengthening of mediating events associated with each sample.

A cytological study of the ovary of Rhodnius prolixus. III. Cytoarchitecture and development of the trophic chamber

Abstract: The tropharium of the telotrophic ovarioles of Rhodnius is syncytial with the nurse cell nuclei located in tortuous finger-like projections arborizing from a common cytoplasmic area, the trophic core. The nurse cell nuclei exhibit prominent nucleoli. Located adjacent to the nuclear envelope are masses of granular material both within the nucleus and adjoining cytoplasm. The cytoplasm consists primarily of ribosomes and mitochondria. The trophic core and the trophic cords that connect the core to individual oocytes characteristically possess parallel arrays of microtubules with ribosomes and mitochondria interspersed between. Surrounding the nurse tissue (germarium) is a thin layer of squamous cells comprising the inner sheath. The inner sheath is encompassed by the non-cellular tunica propria superficial to which are two external cellular sheaths. The syncytial nature of the tropharium appears to arise as a result of the fusion of many entangled nurse cell-oocyte complexes during the late fifth instar. The structural similarities, and possible homologies with the polytrophic type of ovariole is discussed.

Genetic evidence for fewer progeny and a higher percent males when Nasonia vitripennis oviposits in previously parasitized hosts

Abstract: Genetically markedNasonia vitripennis females that oviposited second or third on aSarcophaga bullata pupa produced fewer progeny than those that were the first to oviposit on the host. The proportion of males in these progeny was also significantly increased (p.<0.001). Implications of these results on the evolution of hymenopterous parasites are discussed.

A cytological study of the ovary of Rhodnius prolixus. II. Oocyte differentiation.

Abstract: This investigation presents the ultrastructural changes that occur during previtellogenic and vitellogenic growth of the oocyte of a telotrophic ovary. The ovarioles of a newly emerged adult Rhodnius have their full complement of oocytes located at the base of the tropharium. These oocytes are in cytoplasmic continuity with the syncytial tropharium via trophic cords. The nuclei of these oocytes are in prophase of meiosis I with condensed chromosoes; synaptonemal complexes are visible in many. During oocyte growth the nucleus or germinal vesicle enlarges from a 3–4 μ diameter to a 45–50 μ diameter and the chromosomes become diffuse and arrested in late prophase I. Small previtellogenic oocytes are limited by a morphologically unspecialized oolemma and contain a pair of centrioles, rough endoplasmic reticulum, a few small Golgi complexes and clusters of mitochondria. By the end of previtellogenesis there has been an increase in the volume of the oocyte due to the transport of ribosomes and mitochondria into the oocyte from the tropharium. During vitellogenesis the oolemma develops a microvillous border and yolk precursors are internalized by pinocytosis. Small stacks of annulate lamellae, numerous ribosomes and the other organelles are restricted to the thin layer of cortical ooplasm; the lipid protein-carbohydrate yolk spheres and glycogen are located centrally. In oocytes not stimulated, autolysis occurs as dense local areas within the ooplasm.

Evidence against genetic self-incompatibility in the homosporous fern pteridium aquilinum.

Abstract: Pteridium aquilinum is the only pteridophyte which supposedly possesses a genetic self-incompatibility system (Wilkie, 1956). Wilkie studied spore collections originating from three different sporophytes growing in Scotland. Populations of isolated hermaphroditic gametophytes established from these spore collections failed to form sporophytes when only selfing was possible. When populations of pairs of sister gametophytes (having a common parental sporophyte) were grown and allowed to cross fertilize, 50% of such pairs failed to form sporophytes. These observations indicated the presence of a single locus, multiple allelic, self-incompatibility system in this fern. This paper presents genetic data for five varieties of Pteridium aquilinum which suggest that self-incompatibility is not true of the entire species.

Natural and artificial rephasing of a tidal rhythm

Abstract: 1. Populations of the sand-beach isopod,Excirolana chiltoni, show rhythmic swimming activity, under non-tidal conditions in the laboratory. The underlying period of this rhythm approximates the double-tidal interval of 24.8 hours rather than the tidal interval of 12.4 hours. 2. Three patterns in swimming activity were observed: 1) diurnal activity, in which one peak of activity was observed each day; 2) semidiurnal equal activity, in which two peaks of equally intense activity were observed, and; 3) semidiurnal unequal activity in which a high level activity peak alternating with a low level activity peak was observed. The ability to perform each of these patterns resides in single individuals. 3. The pattern of activity which was observed in any particular experiment reflected the wave form of the tide on the day preceding confinement of the population in the laboratory (Figs. 1 and 2). 4. The application of turbulence cycles, in the laboratory, which simulate wave action on the beach can phase shift the ongoing rhythm of a population and can initiate rhythmic activity in previously arhythmic populations. One stimulus application per day initiates diurnal activity while two stimuli evoke semidiurnal activity. The effect of turbulent stimuli persists for several days after cessation of treatment indicating a long lasting conditioning effect of these stimuli on the pattern of endogenous activity (Figs. 6–10).

In situ shear wave velocity by cross-hole method.

Abstract: The cross-hole seismic survey technique is presented as a means of determining in situ shear wave velocity. By this method the travel time for body waves to travel between two points in a soil mass is measured. Body waves may be either compression or shear waves. Emphasis is placed on identification of the shear wave because it is directly used to calculate the dynamic shear modulus of the soil and can be measured above or below the water table. A general procedure followed in performing the test is described. Typical travel time records of arriving energy are shown and identification of the compression and shear wave arrivals made. Preliminary tests demonstrating the validity and use of the method are presented. Three case studies using the method under various field conditions are also presented.

The Widowed Who Live Alone: An Examination of Social and Demographic Factors

Abstract: In the last decade considerable research has been done on various aspects of the contracting American family. The trend from the larger kin group to the nuclear family has been widely discussed. A logical development in the examination of this trend is the exploration of the last stage of the family cycle: widowhood. Since residence and composition of households are two of the keys to an examination of the social structure of the family, this study is based on data from the one-in-a-thousand sample of the 1960 United States Census (Bureau of the Census, 1964). This sample yielded data on 9,875 widowed persons with a variety of living arrangements during their widowhood. Variables examined were age, race, sex, educational achievement, income, labor force status, ethnicity, place of residence, fertility and marriage, all of which have a bearing on the living arrangements of the widowed. It has been claimed that basic changes in tradi

Goodness of Fit Tests for the Gamma and Exponential Distributions

Abstract: Goodness of fit tests based on generalized minimum x 2 techniques are developed for the gamma and exponential distributions. The power of these tests has been found for several alternative families of distributions by utilizing the asymptotic non-null distribution of the test statistic. The tests behave very well for the types of alternatives considered here. Applications to some failure data of Proschan (1963) are included for illustrative purposes.

What Are the Benefits of Unit Pricing

Abstract: Does unit-price information alter purchase decisions of consumers in supermarkets? Will the change to a unit-pricing system create burdensome costs for retailers? The authors report the results of ...

The effects of sexually arousing and violent films on aggressive behavior

Abstract: Arnong the various concerns regarding the effects of mass media is the almost perennial worry about the effects of the media's depictions of sex and violence on audience behavior. The most visible evidence of this concern presented itself in the emergence of two Presidential Commissions which stlldied (aluong other things) the behavioral effects of sexually arousing material and mass tnedia violence. Both the Commission on Obscenity and Pornography (1970) and the National Commission on the Causes and Prevention of Rliolence (1969) examined the present states of research findings and initiated further studies in both areas and advanced conclusions and recornn-lendations based on their reviews of the available evidence. Despite the independence of both inquiries, one interesting area to emerge from the Obscenity and Pornography Commission's investigation was the study of the relationship between the behavioral effects of sexually arousing media content and violent media content. While sexual behavior and aggressive behavior may appear at first glance to be distinctly different types of behavior, comparisons of physiological characteristics of the organism in both states of arousal show a great deal of similarity. Kinsey (1953) made note of this occurrence when he observed that of the fourteen basic physiological changes taking place during sexual and aggressive arousal, only four differ between the two states. Storr (1970) has further noted that it "is not uncommon for one response to suddenly change into the other" (p. 18). Several studies done at the request of the Obscenity and Pornography Commission attempted to identify the relationship between aggressive and sexual arousal states. The theoretical basis for these studies hypothesizes that emotional arousal is a general state within