Showing papers by "University of Massachusetts Boston published in 1975"

Brood or broadcast? The adaptive significance of different reproductive strategies in the two intertidal sea stars Leptasterias hexactis and Pisaster ochraceus

Abstract: This paper considers the adaptive significance of two different reproductive methods in two co-occurring, competing sea stars. The smaller (3 to 8 g mean wet weight) Leptasterias hexactis broods relatively few, large young in the winter, while the large (300 to 650 g mean wet weight) Pisaster ochraceus broadcasts relatively many, small eggs each spring. L. hexactis matures at a small size (2 g wet weight) in about 2 years, and P. ochraceus matures at a larger size (70 to 90 g wet weight) in about 5 years (Menge, 1974). As in many broadcasting asteroids, gonad and storage organ indices of P. ochraceus are inversely related over time, and maximum storage-organ index correlates with the summer feeding maximum (Mauzey, 1966). In contrast, both organ indices of L. hexactis and feeding increase and are positively correlated until early autumn, when feeding activity begins to decline. At this time the male gonad index continues to rise, and the storage-organ index drops. In contrast, both organ indices of females rise. Spawning occurs from November to January. Thereafter storage-organ indices decline in females, presumably because females draw upon energy reserves while brooding; storage-organ indices rise in males, presumably because males do not brood and can feed if food is available. The primary cause for the differences between annual reproductive cycles of P. ochraceus and L. hexactis is suggested to be patterns of food availability for the released young (planktonic food for the broadcasted young of P. ochraceus and benthic prey for the brooded young of L. hexactis. Estimates of pre-maturity survival and post-maturity longevity indicate that the probability of survival per individual of young P. ochraceus is vastly lower than that of L. hexactis. However, once mature, P. ochraceus has a much longer expected lifespan. Brooding is suggested to be a coadaptive consequence of competition-induced small size. Assuming planktonic mortality rates in this environment are roughly constant across broadcasting species, I suggest that a small broadcasting species could not produce enough offspring in its expected lifespan to replace itself. This hypothesis is partly supported by some simple simulations. Broadcasting is suggested to permit rapid location and utilization of spatially and temporally unpredictable, but highly desirable, resources by allowing rapid and widespread dispersal. Brooders presumably cannot disperse rapidly and must rely on more reliable, but perhaps less desirable, resources. Factors affecting reproductive patterns in marine invertebrates include (1) food availability for both adults and offspring, (2) planktonic mortality rates, (3) interactions between species and latitudinal changes in these factors, and (4) various physical factors. This paper suggests that competition and predation can have an important effect on the evolution of reproductive methods, a possibility heretofore largely ignored. Although several similar examples of co-occurring species' pairs which differ in reproductive method and size are available, the role of adult interactions is unknown in these examples.

Fusion of hen erythrocytes with yeast protoplasts induced by polyethylene glycol.

Abstract: POLYETHYLENE glycol (PEG) has been used to induce the fusion of protoplasts of higher plants1,2. Ahkong et al.3 have also observed that PEG will cause hen erythrocytes to fuse to form binucleate and multinucleate cells. The availability of a common chemical agent that can be used effectively for the fusion of both animal cells and plant protoplasts has prompted us to investigate the possibility that PEG may likewise induce interspecific fusion between hen erythrocytes and yeast protoplasts.

Liquid crystal phase diagrams: A study of seven thermotropic materials

Abstract: We report and discuss the pressure–temperature phase diagrams for seven materials having liquid crystal phases: N‐ (p‐methoxybenzylidene) ‐p‐butylaniline (MBBA), N‐ (p‐ethoxybenzylidene) ‐p‐butylaniline (EBBA), N‐ (p‐methylbenzylidene) ‐p‐butylaniline (MBA), cholesteryl oleyl carbonate (COC), 4,4′‐bis (heptyloxy) ‐azoxybenzene (HAB), cholesteryl nonanoate (CN), and N‐ (p‐cyanobenzylidene) ‐p‐octyloxyaniline (CBOOA).

Age, smoking inhalation, and pulmonary function.

Abstract: • This study examined the relative effects of age and smoking on pulmonary function. Smoking was measured by six smoking variables, taken singly and as a composite. Subjects were 1,510 male participants in the Normative Aging Study. A stepwise multiple regression with vital capacity (VC) and forced expiratory volume at one second (FEV1.0) as the criteria accounted for 24.4% and 28.3% of the variance, respectively. Two-way analyses of variance showed that the age decline in pulmonary function was substantially greater for high inhalers than it was for low inhalers or nonsmokers. Age and the inhalation index were also noticeably and independently related to a decline in pulmonary function.

The bohras of east africa

Abstract: lords, craftsmen, artisans and professionals. They belong to the Musta'lian Isma~ili sect of Islam and were converted from several Hindu castes, some eight hundred years ago. The name Bohra (also Bohora) denotes a "trader, merchant" (from the Gujarati vohorvu, "to trade") and records the occupation of the first converts to Islam 1). Ancestors of the present Bohras came to East Africa in the nineteenth century from Gujarat particularly from the district of Cutch and Kathiawar, though some Yemeni Bohras from Southern Arabia have also settled here. Out of an estimated half a million Bohras scattered all over the world, the majority being in India, East Africa has about 15,0002). Although a small minority, the Bohras have succeeded in preserving their identity, and religious and cultural traditions. Like other minorities in East Africa they are organized into an exclusive endogamous group, locally known as a 'community'. So far very little has been written about this interesting entrepreneurial and religious group. The present study is a survey of the origins and migration of the Bohras to East Africa and their religious beliefs and organization. It is based on the author's lengthly experience of living with the Bohras

The Dilogarithm function of a real argument [S22]

Abstract: The dilogarithm function [1-3], defined by Li2(x) = - ∫x0 (1/z) ln (1 - z) dz, (1) occurs in several different applications in physics and engineering, ranging from quantum electrodynamics, to network analysis, to the thermodynamics of ideal ferromagnets, to the structure of polymers. A new function subroutine is developed which computes the dilogarithm function of a real argument to an accuracy of a few parts in 1015. This program was designed to be included in the usual package of library subprograms relied upon by most users. It employs an alternative computational approach to a previously published algorithm [4].

The Economic Role and Value of Volunteer Work in the United States: an Exploratory Study:

Abstract: Each year millions of American men, women and children---like their counter-parts in Europe and Asia (cf. Smith 1974)---serve as unpaid volunteers and contribute a significant volume of uncounted production to the national welfare. This uncounted output spans a considerable portion of the wide range of services (some of which are themselves imputed) included in the Personal Consumption Expenditure component of the United States Income and Product Accounts (U.S. Income and Output 1958). On the income side of the accounts, the imputed value of volunteer activities may be viewed as an addition to labor compensation. In terms of income and product originating by industry, the bulk of volunteer activity represents an addition

Is Death is Life Crisis? On the Confrontation with Death in Theory and Practice

Abstract: ABSTARCT Life and death are not strangers to each other. However, life-span developmental theory as such has taken little notice of death and dying. This exploration of possible relationships between the two realms offers a discussion of death as variable, event, state, analogy, and mystery. Detailed consideration is given to a well-known stage theory of dying, and selected problems in theory and practice are then identified. Caution is advised against the premature enshrinement of death as one more “normative life crisis.”

Workers, Trade Unions, and the Mau Mau Rebellion

Abstract: RESUMELes masses urbaines ont joue un role etonnamment important lors de la revolte mau-mau au Kenya, et le mouvement ouvrier a ete aussi profondement implique Cependant, a la fois dans la classe ouvriere et dans le mouvement ouvrier, il y eut des differences de perception politique Les vues du role politique des travailleurs en Afrique, comme celles de Hodgkin, Woddis ou Fanon, ne cernent pas toute la complexite de la situation au KenyaAlors que le mouvement nationaliste etait scinde entre une aile moderee et l'aile militante mau-mau, les travailleurs Kikuyu de Nairobi appuyaient pleinement la rebellion Les travailleurs Kikuyu non specialises formaient un contingent important ou se recrutaient les combattants mau-mau alors que les travailleurs specialises appuyaient passivement la revolte Ceux qui ne l'appuyaient pas avaient tendance a etre des collets blancs Ces divergences dans le statut economique des travailleurs se revelaient politiquement significatives Dans les unions ouvrieres, qui represe

Liking and self-disclosure in opposite sex dyads.

Abstract: A review of studies of self-disclosure indicated that own self-disclosure was more often related to liking for partner than was other's self-disclosure and that relationship held for females rather than males. Similarity of content and similarity of amount of self-disclosure between partners have been proposed as conditions which could account for the failure of other's self-disclosure to be related to liking for partner. In a study of self-disclosure by 59 dyads of both sexes during an initial laboratory meeting, only the relationship between own self-disclosure and liking for partner was significant and then only for females. Reassessment of theory and methods for studying the relationships are needed.

Effects of Desegregation on Achievement-Relevant Motivation

Abstract: In spite of public acceptance of the democratic ideals of school desegregation, many citizens have expressed serious reservations about bussing. The one advantage that could possibly outweigh the costs, in the eyes of some critics, would be a significant improvement in the academic performance of the desegregated minority children. As indicated in Chapter 1 underlying the expectation of such an improvement has been the belief that through interracial contact minority children will develop the motivations and values that are presumed to be the necessary mediators of academic achievement. Included in the battery of instruments administered to our sample children were several measures designed to assess achievement motivation. These measures were included in order to provide data for detecting if, in fact, a change in values occurred and further to examine the relationships between change in values and change in achievement. In the initial sections of this chapter we will review the framework of reasoning and research that bears on our notions about motivation and school achievement and that underlies the expectation that desegregation can have a beneficial impact on minority children. The latter sections will discuss the measures in some detail and present a summary of our findings.

Black Faculty Members At Multiracial Campuses: Some Problems of Modeling Roles

Abstract: On a few occasions recently the author found the topic of the presence of Black faculty on predominantly White college campuses the center of rather intense concern among Black students at those campuses. In one situation, a party given by some undergraduates, a need was expressed for guidance from Black faculty members in study skills and for examinations scheduled early in the term so that sfudents could pace themselves. While the students disapproved of "easy grades" and were contemptuous of courses where there was no challenge, they also tended to feel more at ease with younger Black faculty members. However, where a younger Black teacher was "too hard" on Black students she was resented. She had announced to some Black students, "I've got mine, now you've got to get yours." At a reception for a faculty member at Harvard University, a Black dental student commented, "There are times when you want to ask a professor about something, but they make

Biochemical characterization of esterase isozymes of the marine snail, littorina littorea

Abstract: . Littorina littorea is a hardy intertidal snail which can withstand a broad range of environmental conditions, including pollution of various kinds. Its enzymes are being studied as part of an exploration of this adaptability. The esterases of L.littorea have been characterized according to substrate and inhibitor specificities and are evaluated as potential markers for population studies involving this organism. Eight regions of esterase activity are described, five of which are biochemically unique and at least seven of which are polymorphic. The phenotypes of these regions are presented and possible interpretations discussed.