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Showing papers by "University of Massachusetts Amherst published in 1970"


Journal ArticleDOI
TL;DR: In this paper, it is shown that the initial conditions of galaxy formation are metric fluctuations at the threshold epoch of classical cosmology, and that the spin fluctuation gives an eventual angular momentum of the order of 4 3 √ n in reasonable agrement with that of the Galaxy.
Abstract: The "threshold epoch" of classical cosmology is first discussed from a classical point of view. It is shown that if the density fluctuations at this epoch are proportional to ${N}^{\ensuremath{-}n}$ (where $N$ is the number of particles in a disturbance), then $n$ must exactly, or very closely, equal the value $\frac{2}{3}$ in order that such fluctuations develop into protogalaxies. This result is independent of the value of the threshold epoch, and of the equation of state for the very early universe. Arguments of a speculative nature are then presented which indicate that the threshold epoch occurs at the Planck density. It is also proposed that the initial conditions of galaxy formation are metric fluctuations at the threshold epoch of classical cosmology. The evidence in favor of this theory is (i) the density fluctuation obeys the $n=\frac{2}{3}$ rule, and (ii) the spin fluctuation gives an eventual angular momentum of the order ${N}^{\frac{4}{3}}\ensuremath{\hbar}$, in reasonable agrement with that of the Galaxy.

429 citations


Journal ArticleDOI
TL;DR: In this article, a mixture of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and atactic polystyrene (PS) has been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments.
Abstract: Blends of poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and atactic polystyrene (PS) have been prepared by mechanically mixing powders of the two polymers and subjecting the mixtures to three different thermal treatments. Three different compositions were studied by the dynamic mechanical and DSC techniques. The weight fractions of PPO in the mixtures were 0.25, 0.50 and 0.75. The dynamic mechanical measurements indicate that partial mixing took place but that two distinct phases, one rich in PS and the other in PPO, exist in all the mixtures studied. Each phase exhibits a characteristic relaxation peak associated with the glass transition of that phase. DSC measurements, on the other hand, reveal only a single glass transition apparently characteristic of the PS rich phase in each case. The results indicate that a given type of experiment will indicate compatibility or incompatibility depending upon the size of the molecular process it represents.

152 citations


Journal ArticleDOI
01 Mar 1970-Ecology
TL;DR: The contribution to forest regeneration of seeds stored by these small forest mammals is probably of minor significance except when bumper seed crops are produced and large numbers of caches are created.
Abstract: Typical seed caches made in the fall of the year by white—footed mice (Peromyscus leucopus) and red—backed voles (Clethrionomys gapperi) contained 20—30 pine seeds, buried beneath the litter of pine needles and in contact with mineral soil. Many caches were revisited by the mice and their contents destroyed before winter. Most caches not decimated in the fall were invaded the following spring. However, some of them escaped complete destruction and their unconsumed seeds germinated and produced seedlings. Although mice make their caches in micro—environments highly favorable to germination, their subsequent feedings on the stored seeds, both before snowfall and before and during the spring germination period, greatly deplete the number of potential germinants. Therefore, the contribution to forest regeneration of seeds stored by these small forest mammals is probably of minor significance except when bumper seed crops are produced and large numbers of caches are created. Under these circumstances, stored seeds may be of sufficient quantity to exceed food requirements of the mice. If pirating by other animals is low, then a surplus of seeds is left to help regenerate the forest.

142 citations


Journal ArticleDOI
TL;DR: In this article, high-density commercial polyethylenes have been crystallized under the combined orientation and pressure effects available in the Instron capillary rheometer, and the samples so formed were found to have a high degree of crystal perfection and crystal orientation in combination with the unusual property of transmitting visible light.
Abstract: High-density commercial polyethylenes have been crystallized under the combined orientation and pressure effects available in the Instron capillary rheometer. The samples so formed were found to have a high degree of crystal perfection and crystal orientation in combination with the unusual property of transmitting visible light. The procedure for forming the crystal structure is elucidated. X-Ray and differential scanning calorimetry techniques were utilized to initiate a study of the structure. Evidence is presented that is consistent with the presence of an extended chain component in the crystal structure.

135 citations


Journal ArticleDOI
TL;DR: In this paper, the fatigue of soda-lime, E, borosilicate, and fused quartz glass was studied using both static and dynamic tests, and the theoretical implications of these results are discussed.
Abstract: Fatigue of silicate glasses was studied using both static and dynamic tests. Static fatigue data for acid-etched soda-lime silicate glass determined at 74°F in 50 and 100% rh can be represented by a single universal fatigue curve (UFC). The UFC for acid-etched glass does not lie on the UFC of Mould and Southwick, which was determined for abraded soda-lime silicate glass; the acid-etched glass was less susceptible to static fatigue. The susceptibility of acid-etched soda-lime silicate glass to static fatigue differed little from that of pristine E-glass and fused SiO2 fibers. Dynamic fatigue data for soda-lime, E, borosilicate, and fused quartz glasses agreed well qualitatively and quantitatively with fundamental crack velocity data for these glasses; the dynamic fatigue theory of Charles was used in the comparison. The theoretical implications of these results are discussed.

135 citations


Journal ArticleDOI
TL;DR: Together, adaptation and loss of genetic capacity are the major contributors to overall reproductive fitness and accidental selection is genetically associated with adaptation, but is not goal‐directed.
Abstract: Summary 1. Adaptation and loss of genetic capacity differ chiefly in that adaptation is goal- directed whereas loss of genetic capacity is not. Given sufficient information about an individual organism and its environment, adaptations are recognizable without reference to historical events extending beyond a single generation. This is not true of loss of genetic capacity, which requires a preliminary judgement that genetic information now absent was present in ancestral organisms. Together, adaptation and loss of genetic capacity are the major contributors to overall reproductive fitness. Accidental selection is genetically associated with adaptation, but is not goal-directed. 2. Adaptations arevariant or invariant; invariant adaptations comprising biochemical unity, and variant adaptations contributing to biochemical diversity. Variant adaptations may be either exploitive or epigenetic. Exploitive adaptations are a measure of thegenetic capacity for phenotypic response to an altered environment, which the individual may not in fact encounter. Epigenetic adaptations are more rigidly programmed and are responsive to altered environments only insofar as these are a constant feature of the life cycle. 3. Selected observations in the biochemistry of helminth parasites are examined with respect to their interpretation in terms of adaptation, loss of genetic capacity and accidental selection. Secure judgements concerning adaptation are often possible at the most general level, i.e. when the physicochemical properties of the environment, such as temperature or oxygen supply, are clearly defined. I t is more difficult to make judgements concerning the specific mechanisms used in achieving these goals. Conclusions concerning loss of genetic capacity require knowledge of the specific function through-out the life cycle. In many cases loss of genetic capacity is only apparent, as the function appears in another part of the life cycle. Such apparent losses are in reality epigenetic adaptations. These concepts are helpful in interpreting past work and in devising new experiments. 4. Development in helminth parasites includes a pronounced capacity for the orderly release of information to be used in the next stage. As each stage may require a radically different environment, programming for it may lead to phenomena which are superficially puzzling, such as the existence of aerobic electron transport systems in a stage whose energy metabolism is fermentative. The concept of epigenetic adaptation is especially useful for interpreting such observations. 5. Although possible adaptations are most readily apparent in biochemically complex mechanisms, these mechanisms are an expression of the orderly effects of many different primary gene products which have not been much studied. There are indications that organisms possessing relatively complex life cycles may provide opportunities for relating primary gene products, such as isozymes, to their physiological functions.

114 citations



Journal ArticleDOI
TL;DR: The reaction of styrene and triamminetricarbonylchromium in refluxing dioxane gives styrenetric bonyl chromium in 50-65% yield as discussed by the authors.

112 citations


Journal ArticleDOI
TL;DR: In this article, the de Haas-van Alphen amplitude of the oscillations of the magnetization as a function of temperature in mercury was calculated for a system of electrons interacting with phonons in the presence of a magnetic field.
Abstract: The thermodynamic potential and magnetization are calculated for a system of electrons interacting with phonons in the presence of a magnetic field. The results are used for a numerical evaluation of the de Haas-van Alphen amplitude of the oscillations of the magnetization as a function of temperature in mercury. The calculated results show that although we are dealing with a strong-coupling system, the experimental observations of the de Haas-van Alphen effect should be very similar to that expected for free particles. We also apply the techniques used in the derivation to the case of nearly ferromagnetic electron systems and calculate the enhancement of the argument of the spin-splitting factor. The analysis for nearly ferromagnetic systems leads to the prediction that the cyclotron frequency which enters the amplitude of the oscillations is reduced by the same mass-enhancement factor as that which enters the specific heat.

111 citations


Journal ArticleDOI
TL;DR: Rats with lateral hypothalamic electrodes self-stimulated at higher rates at threshold current intensities while under chlordiazepoxide (CDP) than under no-drug conditions, and it is suggested that CDP modulates the activity of a negative rather than a positive neural system.

103 citations


Journal ArticleDOI
TL;DR: The glyoxylate cycle and the conversion of 4-carbon dicarboxylic acids to trehalose and glycogen account for the unique synthesis of carbohydrate from higher fatty acids.

Journal ArticleDOI
TL;DR: Experimental verification of the application of the integrating sphere or cavity to the measurement of the absorption coefficient (cm(-1)) of a material introduced into the cavity is described showing agreement with direct transmittance measurements to within +/-10%.
Abstract: This paper describes the application of the integrating sphere or cavity to the measurement of the absorption coefficient (cm−1) of a material introduced into the cavity. The absorption coefficient is determined by measuring the decrease in the radiation density within the integrating cavity caused by insertion of the sample. This method has the virtue of being independent of the scattering within the material sample, the reflectivity of the material surface, and the geometry of the sample. The method is particularly attractive for materials with small absorption coefficients. Experimental verification of the method is described showing agreement with direct transmittance measurements to within ±10%.

Journal ArticleDOI
TL;DR: The complex interactions of quality of sources with hue, value, and chroma of object and background colors on aesthetic responses to colors help to account for the conflicting statements often found in the literature regarding color harmony.
Abstract: Effects of spectral energy distributions of sources and colors of backgrounds on the pleasantness of object colors were determined by having 5 men and 5 women rate 125 object colors on 25 colored backgrounds in 5 sources of illumination. In addition, foods and complexions were rated in the same sources. All main effects were found to be highly significant statistically. While lightness and chromatic contrasts of object and background were more important than quality of illuminants, the latter were very important in the case of some object and background color combinations. Differences between the sexes were highly significant in that men tended to prefer cool source, object, and background colors, women the warm colors. The best colors for backgrounds had either low chroma and high reflectance (the pastel colors), or low chroma and low reflectance. The most important single factor determining the pleasantness of color combinations was lightness contrast. Hue and chroma contrasts, while of some importance, were not as decisive as lightness contrast. Some closely related color families may be substituted for each other, e.g., 5 and 10R or 5 and 10G, while others may not be, e.g, 5 and 10GY. The complex interactions of quality of sources with hue, value, and chroma of object and background colors on aesthetic responses to colors help to account for the conflicting statements often found in the literature regarding color harmony. In spite of the complexities of the problem, some generalizations regarding color harmony were found valid and others were shown to be in need of further investigation. This study was based on 156,250 individual ratings of object colors.

Journal ArticleDOI
TL;DR: The shell glands of the brine shrimp Artemia are composed of clusters of shell gland units, each unit usually consists of two rather oblong cells separated by a lumen, which communicates with the uterus by a duct.


Journal ArticleDOI
TL;DR: Breakdown of the germinal vesicle in inseminated eggs of the surf clam, Spisula solidissima, consists of a vesiculation of its nuclear envelope and the condensation of its chromatin.

Journal ArticleDOI
TL;DR: It is proposed that the marine isolate be considered a new species and that it be named Spirochaeta litoralis.
Abstract: A strictly anaerobic spirochete was isolated from a sample of marine mud. The organism possessed two axial fibrils entwined with the regularly coiled protoplasmic cylinder. An outer envelope or sheath enclosed both protoplasmic cylinder and axial fibrils. The spirochete grew in chemically defined media containing glucose, amino acids or NH4Cl, sulfide, NaCl, vitamins, coenzyme A, and in-organic salts. A reducing agent, such as sodium sulfide or l-cysteine, as well as exogenous supplements of biotin, niacin and coenzyme A were required for growth. Pantothenate replaced coenzyme A as an exogenous growth factor, but the resulting cell yields were low. The spirochete grew in media prepared with sea water, but not in fresh water media containing less than 0.05 M NaCl (optimum concentration 0.35 M). Both Na+ and Cl- were required. Carbohydrates served as fermentable substrates. Amino acids, sugar alcohols, tricarboxylic acid cycle intermediates, and other organic acids and alcohols were not fermented. Glucose was fermented to ethyl alcohol, acetate, CO2, H2, and small amounts of lactate, formate and pyruvate. The guanine + cytosine content of the DNA of the spirochete was 50.5 moles-% (buoyant density). It is proposed that the marine isolate be considered a new species and that it be named Spirochaeta litoralis.

Journal ArticleDOI
TL;DR: Development and investigation of experimental and commercial strains of animals selected in divergent directions for growth has begun at a number of stations, finding two strains of White Plymouth Rock chickens having vastly different rates of growth.

Journal ArticleDOI
TL;DR: In this article, high-density commercial polyethylenes have been crystallized under the combined orientation and pressure effects available in the Instron capillary rheometer, and the samples so formed were found to ha...
Abstract: High-density commercial polyethylenes have been crystallized under the combined orientation and pressure effects available in the Instron capillary rheometer. The samples so formed were found to ha...

Journal ArticleDOI
TL;DR: In this article, the authors considered the reflection and transmission of plane harmonic waves in a flowing medium, by an infinite set of flat plates of arbitrary spacing and stagger, and the problem of solving this equation subject to the pertinent boundary conditions is converted into two consecutive Wiener-Hopf problems.

Journal ArticleDOI
TL;DR: Eggs of the sea urchin, Arbacia punctulata, treated with 3% urethane for 30 sec followed by 0.3% Urethane and inseminated are polyspermic and fail to undergo a typical cortical reaction.
Abstract: Eggs of the sea urchin, Arbacia punctulata, treated with 3% urethane for 30 sec followed by 0.3% urethane and inseminated are polyspermic and fail to undergo a typical cortical reaction. Upon insemination the vitelline layer of urethane-treated eggs either does not separate or is raised only a short distance from the oolemma. 1–6 min after insemination, almost all of the cortical granules remain intact and are dislodged from the plasmalemma. Later (6 min to the two-cell stage) some cortical granules are released randomly along the surface of the zygote. Not all zygotes show the same degree of cortical granule dehiscence; most of them experience little if any granule release whereas others demonstrate considerably more. The thickness of the hyaline layer appears to be directly related to the number of cortical granules released. Subsequent to pronuclear migration, several male pronuclei become associated with the female pronucleus. Later the male and female pronuclear envelopes contact and the outer and the inner laminae fuse, thereby forming the zygote nucleus. The male pronuclei remaining in the cytoplasm increase in size and progressively migrate to, and fuse with, the zygote nucleus. By 60 min some zygotes appear to contain only one large zygote nucleus which subsequently enters mitosis. Other zygotes possess a number of male pronuclei which remain unfused, and later these pronuclei along with the zygote nucleus undergo mitosis. There does not appear to be a direct relation between the number of cortical granules a zygote possesses and the above mentioned dichotomy.


Journal ArticleDOI
TL;DR: The number of sperm incorporated into eggs made polyspermic with varying concentrations of nicotine (0.025–0.25%, v/v) appears to be directly related to the concentrations employed, and the cortical response is morphologically equivalent to that observed in control preparations.
Abstract: The number of sperm incorporated into eggs made polyspermic with varying concentrations of nicotine (0.025–0.25%, v/v) appears to be directly related to the concentrations employed. The cortical response is morphologically equivalent to that observed in control preparations. Shortly after their incorporation all of the spermatozoa undergo structural events normally associated with the development of the male pronucleus in monospermic eggs. During the reorganization of the spermatozoa, sperm asters are formed. The number of male pronuclei that initially migrate to and encounter the female pronucleus is usually one to three. When pronuclei come into proximity to one another the surface of the female pronucleus proximal to the advancing male pronuclei flattens and becomes highly convoluted. Subsequently, the pronuclei contact each other and the outer and inner membranes of the pronuclear envelopes fuse, thereby producing the zygote nucleus. The male pronuclei remaining in the zygote after this initial series of pronuclear fusions continue to differentiate, i.e. they enlarge, form nucleolus-like bodies, and undergo further chromatin dispersion. In approximately 90% of the zygotes, all of the remaining male pronuclei progressively migrate to the zygote nucleus and fuse to form one large nucleus by 80 min postinsemination. Mitosis and cleavage of the polyspermic zygote occurs later than in monospermic eggs.

Journal ArticleDOI
TL;DR: In this paper, the effect of changing temperature on the physical environment of the fish is discussed in relation to these observed responses, and the relationship between cardiac and ventilatory cycles was not studied in great detail, but there were certainly indications of changes in coupling.
Abstract: 1. Trout subjected to changes in water temperature (1°/3 min.) between 15° and 30° C. showed a number of responses in their ventilation and cardiac mechanisms. 2. Ventilation rate increased slowly over the range 15°-21° C., but increased more rapidly at higher temperatures (21°-26°, Q 10=2.34; 26°-28°, Q 10=4.02). Cardiac frequency fell markedly about 26° C., and this bradycardia suggests that above this temperature the ventilation mechanism is inadequate to maintain a sufficient level of blood P o . Possibly this insufficiency results from a failure of the pumping mechanism to increase or even maintain a large minute volume at high frequencies. 3. Pressure recordings indicate those parts of the ventilatory mechanism which are mainly involved in these responses. Increases in the buccal, opercular, and mean differential pressures indicated that the volume of water pumped across the gills increased during the initial stages of warming and only at higher temperatures did frequency become involved. Variability in the balance between the buccal and opercular pumps among individual trout becomes even more apparent under temperature stress, as in some cases the opercular pumps seem to be mainly involved in the increased ventilation but not always. 4. The action of the buccal and opercular pumps seems well co-ordinated, especially at intermediate temperatures, but serious uncouplings occur at higher temperatures as indicated by the shape of the pressure waveforms and especially the appearance of double reversals in the differential pressure curve. 5. The relationship between cardiac and ventilatory cycles was not studied in great detail, but there were certainly indications of changes in coupling. However, it was clear that the two rhythms do not always become phase-locked even at high temperatures. 6. The effect of changing temperature on the physical environment of the fish is discussed in relation to these observed responses.

Journal ArticleDOI
TL;DR: In this paper, the power spectrum of the radiation emitted by a driven collision-damped two-level system is evaluated and the limiting forms of the radiated field are discussed for the cases of low and high excitation of the atomic system.
Abstract: The power spectrum of the radiation emitted by a driven collision-damped two-level system is evaluated. The driving field, which is treated classically, is assumed to oscillate harmonically near the atomic resonance frequency, and its intensity is allowed to assume arbitrary values. The collisions are assumed to be strong, i.e., to instantaneously thermalize the state of the atom. The limiting forms of the power spectrum of the radiated field are discussed for the cases of low and high excitation of the atomic system.

Journal ArticleDOI
TL;DR: (1970).
Abstract: (1970). An Approach to Empirical Logic. The American Mathematical Monthly: Vol. 77, No. 4, pp. 363-374.


Journal ArticleDOI
TL;DR: The authors explored the cultural and situational bases of such a theory of communication failure as a means of explaining and coping with social problems, and evidence for its use in the Cambodian situation is examined; and its possible consequences are suggested.
Abstract: A series of Presidential actions and other events connected with the recent use of U.S. troops in Cambodia suggest a preoccupation with communication (its presence or absence, its process, and its style) that deflected and obscured the basic issue of the war by defining events in terms of a quasi-theory of communication failure. The cultural and situational bases of such a theory of communication failure as a means of explaining and coping with social problems are explored in this paper; evidence for its use in the Cambodian situation is examined; and its possible consequences are suggested. The role of symbolic reassurance in coping with public uneasiness about the war and the anti-war movement is also examined.

Journal ArticleDOI
TL;DR: The events of fertilization involving the incorporation of the spermatozoa, the development of the male pronucleus, and the association of the maternally and paternally derived pronuclei have been investigated in the egg of Spisula solidissima.

Journal ArticleDOI
TL;DR: The rate of disappearance of endogenous lipids, calculated from gravimetric data, closely resembled the rate of oxidation of absorbed palmitate-U-14C throughout development, and both the presence and the function of the enzymes of β-oxidation in developing eggs ofscaris lumbricoides was established.