Showing papers by "Texas A&M University published in 1975"
01 May 1975
TL;DR: The Stability of Globular Protein: A Critical Review in Biochemistry as discussed by the authors, Vol. 3, No. 1, pp. 1-43, was the first publication of this paper.
Abstract: (1975). The Stability of Globular Protein. CRC Critical Reviews in Biochemistry: Vol. 3, No. 1, pp. 1-43.
609 citations
TL;DR: In this paper, a theory is developed for predicting the time-dependent size and shape of cracks in linearly viscoelastic, isotropic media, and a local energy criterion of failure at the tip is introduced, which is applicable to both constant and transient tip velocities.
Abstract: A theory is developed for predicting the time-dependent size and shape of cracks in linearly viscoelastic, isotropic media First, the effect of a narrow zone of disintegrating material at the crack tip on opening displacement and on a finite stress distribution ahead of the tip is examined for elastic materials Extension to viscoelastic media is then made Although the undamaged portion of the continuum is assumed linear, no significant restrictions are placed on the nature of the zone of failing material at the crack tip and, therefore, this material may be highly nonlinear, rate-dependent, and even discontinuous Finally, formulation of the problem is completed by introducing a local energy criterion of failure at the tip which is applicable to both constant and transient tip velocities Parts II–IV, to appear in succeeding issues, will cover approximate methods of analysis and several applications of the theory
566 citations
Book•
01 Jan 1975
TL;DR: The scope of insect ecology is examined, including Behavior, mating systems, and sexual selection, as well as population ecology, population dynamics, and population growth and life tables.
Abstract: Combining breadth of coverage with detail, this logical and cohesive introduction to insect ecology couples concepts with a broad range of examples and practical applications. It explores cutting-edge topics in the field, drawing on and highlighting the links between theory and the latest empirical studies. The sections are structured around a series of key topics, including behavioral ecology; species interactions; population ecology; food webs, communities and ecosystems; and broad patterns in nature. Chapters progress logically from the small scale to the large; from individual species through to species interactions, populations and communities. Application sections at the end of each chapter outline the practicality of ecological concepts and show how ecological information and concepts can be useful in agriculture, horticulture and forestry. Each chapter ends with a summary, providing a brief recap, followed by a set of questions and discussion topics designed to encourage independent and creative thinking.
259 citations
TL;DR: In this paper, simple approximate relations are derived for predicting the time of fracture initiation and crack tip tip velocity in linearly viscoelastic media, assuming that the second derivative of the logarithm of creep compliance is small.
Abstract: Starting with equations developed in Part I for the opening mode of displacement, simple, approximate relations are derived for predicting the time of fracture initiation and crack tip velocity in linearly viscoelastic media. First we use the assumption that the second derivative of the logarithm of creep compliance with respect to logarithm of time is small (which is normally valid for viscoelastic materials); we next derive a relation between instantaneous values of tip velocity and stress intensity factor. This result is then used to examine some characteristics of crack growth behavior. Finally, some results are obtained for the separate problem of predicting the time at which propagation initiates.
252 citations
TL;DR: Marked aggression of the tumors was found, leading to the possibility that hyperbaric hydrogen therapy might also prove to be of significance in the treatment of other types of cancer.
Abstract: Hairless albino mice with squamous cell carcinoma were exposed to a mixture of 2.5 percent oxygen and 97.5 percent hydrogen at a total pressure of 8 atmospheres for periods up to 2 weeks in order to see if a free radical decay catalyzer, such as hydrogen, would cause a regression of the skin tumors. Marked aggression of the tumors was found, leading to the possibility that hyperbaric hydrogen therapy might also prove to be of significance in the treatment of other types of cancer.
235 citations
01 Jan 1975
TL;DR: It is probably advantageous for the parasite to evolve towards a condition where the parasite has a minimal affect on the host species, which would insure the continued existence of a viable host population.
Abstract: The coevolution of a predator and its prey suggests that the prey is selected for predator avoidance and escape while the predator is selected for more efficient prey-finding and capture. The predator attacks and consumes its host and, thus being successful, would be expected to propagate. The parasite-host relationship is a similar reciprocating evolutionary relationship with one important difference—the host should not be killed. The parasite must not only locate the host but must constantly adapt to a developing and changing host, a situation resulting in a closely interwoven relationship. The continued development of a host in accord with the evolutionary development of the host species is of benefit to the parasite. It is probably advantageous for the parasite to evolve towards a condition where the parasite has a minimal affect on the host species. This would insure the continued existence of a viable host population.
197 citations
TL;DR: In this article, an experimental investigation of high-temperature seawater/basalt interactions has been conducted in order to better evaluate the geochemical and economic implications of hydrothermal circulation of seawater in the oceanic crust along active mid-ocean ridges.
Abstract: An experimental investigation of high-temperature seawater/basalt interactions has been conducted in order to better evaluate the geochemical and economic implications of hydrothermal circulation of seawater in the oceanic crust along active mid-ocean ridges. The results indicate that, as seawater reacts with basalt between 200 ° C and 500 ° C at 500–800 bars, the fluid tends to change from an oxygenated, slightly alkaline, Na+, Mg++, SO4
=, Cl− solution to a reducing, acidic, Na+, Ca++, Cl−, solution with Fe, Mn and Cu concentrations up to 1500, 190 and 0.3 ppm respectively. Silica concentrations in the fluid reach concentrations of 200–600 ppm; however, Al abundances remain very low (∼0.5 ppm). Gray and green smectites, anhydrite, albite, tremolite-actinolite, chalcopyrite, pyrrhotite and hematite were the dominant alteration products formed. These data imply that large-scale circulation of seawater in the oceanic crust could account for the Al-deficient metalliferous sediments associated with mid-ocean ridges and could be important in the genesis of certain Fe-Cu sulfide ore deposists. The process could also affect the geochemical budgets of certain elements and exert substantial control of the steady-state composition of seawater by removing excess Na and Mg and adding Ca, Si, and H to the oceans.
173 citations
TL;DR: In this article, a simple procedure was developed to fit the first three moments of an actual phase function with a three parameter analytic phase function, which is suitable for multiple scattering calculations.
Abstract: A simple procedure was developed to fit the first three moments of an actual phase function with a three parameter analytic phase function. The exact Legendre Polynomial decomposition of this function is, suitable for multiple scattering calculations. The use of this function is expected to yield excellent flux values at all depths within a medium. Since it is capable of reproducing the glory, it can be used in synthetic spectra computations from planetary atmospheres. Accurate asymptotic radiance values can also be achieved as long as the single scattering albedo omega sub 0 is greater than or equal to 0.9.
161 citations
151 citations
TL;DR: The use of the sampling technique to diagnose metabolic diseases and for application in the study of industrial exposure is reported on.
Abstract: A multistage cryogenic trapping system was used to sample and concentrate trace organic constituents in human respiratory gas. Chemical analysis was conducted by gas chromatography and mass spectrometry. Respiratory compound identification and production rate data are given for eight human test subjects. This study reports on the use of the sampling technique to diagnose metabolic diseases and for application in the study of industrial exposure.
141 citations
TL;DR: This article found that female subjects rated the essay as written by a female as better than the same essay as writing by a male (p <.01) when the author's purported sex was the independent variable.
Abstract: Summary An article by Philip Goldberg in 1968 indicated that college women evaluated articles allegedly written by men more positively than the identical articles attributed to women. Two independent studies were carried out to replicate and extend his study in order (a) to assess the degree to which males reflect a prejudice similar to that of the females and (b) to see if the female of today would be as antifemale as her counterpart in the 1960's. Results from Study I (N = 134), using male and female subjects, indicated that no significant differences were observed when author's purported sex was the independent variable. In Study II, when 145 male and female students were asked to judge a student essay, replies revealed that female subjects rated the essay as written by a female as better than the same essay as written by a male (p < .01).
TL;DR: In this article, a large number of natural marine sediment samples from the Gulf of Mexico were determined through the use of laboratory consolidation tests and a statistical analysis of the natural log of permeability versus porosity was used to develop the permeability prediction equation for each of the groups listed.
Abstract: Permeability of a large number of natural marine sediment samples from the Gulf of Mexico was determined through the use of laboratory consolidation tests. The samples were divided into the following groups: Group 1, sediment consisting of more than 80% clay (material 2 μm or less in size); Group 2, sediment containing from 60 to 80% clay‐size material; Group 3, silty clays with less than 60% clay; and Group 4, silts and clays that have a significant sand‐size fraction present (more than 5% sand). The permeabilities of the groups ranged from 10−5 to 10−10 cm/s with 35% normal seawater being used as the saturating fluid.
A statistical analysis of the natural log of permeability versus porosity was used to develop the permeability prediction equation for each of the groups listed. The equation for Group 1 is k =en(15.05)‐27.37. for Group 2, k=en(14. 18)‐26.50. for Group 3, k= en(15.59)‐26.65. for Group 4 k=en(17.51)‐26.93.and for all data, k = en(14.30)‐26.30; wherc n is the porosity (in decimals) and k is the coefficient of permeability. These equations are useful for predicting changes in permeability with depth in fine‐grained sediments of the Gulf of Mexico. The ability to predict permeability in a continuous sequence, where the deposition history is known, may explain the large variations that we see in the physical properties in sediments similar in grain size and mineralogy.
TL;DR: In this article, a series of experimental studies of consumer demand behavior were conducted using laboratory animals as subjects, showing that laboratory animals will change consumption patterns in response to changes in the budget set, consuming more of the lower priced commodities and less of the higher priced commodities.
Abstract: Using laboratory animals as subjects, two series of experimental studies of consumer demand behavior are reported. The experiments show that laboratory animals will change consumption patterns in response to changes in the budget set, consuming more of the lower priced commodities and less of the higher priced commodities. Large rotations in the budget line for essential commodities resulted in severe disruption of consumer behavior. The experiments demonstrate the feasibility of using non-human subjects in laboratory studies of economic behavior.
TL;DR: In this article, three types of triaxial compression experiments were used to characterize the frictional processes during sliding on quartz gouge and the results indicated that at effective confining pressures of less than 2.0 kb, if a fault zone contains quartz gouges, laboratory-type stick-slip can be an earthquake-source mechanism only if a planar sliding-surface develops, and then only when the effective pressure is less than 0.7 kb.
Abstract: Three types of triaxial compression experiments are used to characterize the frictional processes during sliding on quartz gouge. They are: 1) pre-cut Tennessee Sandstone sliding on an artificial layer of quartz gouge; 2) fractured Coconino Sandstone sliding along experimentally produced shear fractures; and 3) a fine-grained quartz aggregate deformed in compression. The specimens were deformed to 2.0 kb confining pressure at room temperature and displacement rates from 10−2 to 10−5 cm/sec dry and with water. There is a transition in sliding mode from stick-slip at confining pressures 0.7 kb. This transition is accompanied by a change from sliding at the sandstone-gouge contact (stick-slip) to riding on a layer of cataclastically flowing gouge (stable sliding). Quartz gouge between the pre-cut surfaces of Tennessee Sandstone lowers both the kinetic coefficient of friction and the magnitude of the stick-slip stress drops compared to those for a pre-cut surface alone. Stick-slip stress drops are preceded by stable sliding at displacements of 10−5 cm/sec. For a decrease in displacement rate between 10−3 and 10−5 cm/sec, stress-drops magnitudes increase from 25 to 50 bars. Tests on saturated quartz gouge show sufficient permeability to permit fluidpressure equilibrium within compacted gouge in 10 to 30 seconds; thus the principle of effective stress should hold for the fault zone with quartz gouge. Our results suggest that at effective confining pressures of less than 2.0 kb, if a fault zone contains quartz gouge, laboratory-type stick-slip can be an earthquake-source mechanism only if a planar sliding-surface develops, and then only when the effective confining pressure is less than 0.7 kb.
TL;DR: Evidence suggests that poly(ADP-ribose) polymerase may have a functional role in the process of DNA repair.
TL;DR: The data indicate that no single value of leaf water potential will adequately represent a threshold for stomatal closure in cotton, and that each leaf is uniquely related to its own water potential as modified by age and radiation regime during development.
Abstract: The stomatal resistance of individual leaves of young cotton plants (Gossypium hirsutum L. var. Stoneville 213) was measured during a period of soil moisture stress under conditions of constant evaporative demand. When plants were subjected to increasing soil water stress, increases in stomatal resistance occurred first on the lower leaves and the stomata on the upper surfaces were the most sensitive to decreasing leaf-water potential. Stomatal closure proceeded from the oldest leaves to the youngest as the stress became more severe. This apparent effect of leaf age was not due to radiation differences during the stress period. Radiation adjustments on individual leaves during their development altered the stomatal closure potential for all leaves, but did not change the within-plant pattern. Our data indicate that no single value of leaf water potential will adequately represent a threshold for stomatal closure in cotton. Rather, the stomatal resistance of each leaf is uniquely related to its own water potential as modified by age and radiation regime during development. The effect of age on stress-induced stomatal closure was not associated with a loss of potassium from older leaves. Increases in both the free and bound forms of abscisic acid were observed in water-stressed plants, but the largest accumulations occurred in the youngest leaves. Thus, the pattern of abscisic acid accumulation in response to water stress did not parallel the pattern of stomatal closure induced by water stress.
TL;DR: In this paper, two independent analyses of the relative motions of a drifter cluster, two time series of horizontal divergence, vorticity, shear deformation rate, and normal deformation rates are developed.
Abstract: Observations of the motions of drifter clusters were made in the western Caribbean Sea during the summer of 1971. By two independent analyses of the relative motions of a cluster, two time series of horizontal divergence, vorticity, shear deformation rate, and normal deformation rate are developed. The results of the two approaches are very similar. The time series for these differential kinematic properties are fairly smooth when the drifters were moving in the Yucatan Current. Otherwise, the time series are ragged with frequent changes in sign. It is speculated that the raggedness is due to small values of the shear rates relative to random observational errors or small-scale turbulent processes. The records of the differential kinematic properties are used to evaluate the stretching and material derivative terms of the vorticity equation. Calculations indicate that potential vorticity is conserved along trajectories in the Yucatan Current.
TL;DR: In Euphausia superba complex lipids were the major lipid class followed by triglycerides, but the second major constituent was waxes in E. crystallorophias, while the lipids of two Antarctic euphausesiids consisted mostly of phosphatidylcholine with smaller amounts ofosphatidylethanolamine and lysophosphatids.
Abstract: 1. 1. The lipids of two Antarctic euphausiids were characterized. 2. 2. In Euphausia superba complex lipids were the major lipid class followed by triglycerides. 3. 3. In E. crystallorophias the complex lipids were also the major lipid class, but the second major constituent was waxes. 4. 4. The complex lipids of both euphausiids consisted mostly of phosphatidylcholine with smaller amounts of phosphatidylethanolamine and lysophosphatidylcholine. The phospholipids of E. crystallorophias were less unsaturated than those of E. superba. 5. 5. The waxes of E. crystallorophias were mostly esters of oleic (84%) and palmitoleic (10%) acids with n- tetradecanol (69%) and n- hexadecanol (28%).
TL;DR: The radiance in the earth's atmosphere and ocean is calculated for a realistic model including an ocean surface with waves and it is shown that the downward flux just below the surface increases with wind speed at all solar angles.
Abstract: The radiance in the earth's atmosphere and ocean is calculated for a realistic model including an ocean surface with waves. Individual photons are followed in a Monte Carlo calculation. In the atmosphere, both Rayleigh scattering by the molecules and Mie scattering by the aerosols as well as molecular and aerosol absorption are taken into account. Similarly, in the ocean, both Rayleigh scattering by the water molecules and Mie scattering by the hydrosols as well as absorption by the water molecules and hydrosols are considered. Separate single-scattering functions are used which are calculated separately for the aerosols and the hydrosols from the Mie theory with appropriate and different size distributions in each case. The scattering angles are determined from the appropriate scattering function including the strong forwardscattering peak when there is aerosol or hydrosol scattering. Both the reflected and refracted rays, as well as the rays that undergo total internal reflection, are followed at the oceanc surface. The wave slope is chosen from the Cox-Munk distribution. Graphs show the influence of the waves on the upward radiance at the top of the atmosphere and just above the ocean surface and on the downward radiance just below the ocean surface as well as deeper within the ocean. The radiance changes are sufficient at the top of the atmosphere to determine the sea state from satellite measurements. Within the ocean the waves smooth out the abrupt transition that occurs at the edge of the allowed cone for radiation entering a calm ocean. The influence of the waves on the contrast between the sky and sea at the horizon is discussed. It is shown that the downward flux just below the surface increases with wind speed at all solar angles.
TL;DR: The paper describes a direct UV spectrophotometric method for the semiquantitative determination of naphthalene, methylnaphthalenes and dimethylnaphthaenes in sea water and the tissues of marine animals.
Abstract: The paper describes a direct UV spectrophotometric method for the semiquantitative determination of naphthalene, methylnaphthalenes and dimethylnaphthalenes in sea water and the tissues of marine animals.
TL;DR: Antennal olfactory responses to the compounds did not correlate to published data on behavioral responses by the beetles to the compound in both field and laboratory studies, suggesting that the terpene hydrocarbons share some, but not all, of the same receptors.
Abstract: Electroantennograms from males and females ofDendroctonus frontalis andD. brevicomis in response to serial dilutions of the pheromonesexo brevicomin and frontalin and the host terpene hydrocarbons 3-carene and α-pinene show no significant differences in the threshold concentration for response to the compounds for either sex or species. The intensity of response was greater to higher concentrations of the pheromones (10 to >104 μg) than the terpene hydrocarbons, suggesting the presence of more receptors on the antennae for pheromones than terpene hydrocarbons. Antennal olfactory responses to the compounds did not correlate to published data on behavioral responses by the beetles to the compounds in both field and laboratory studies. Adaptation experiments indicated that forD. frontalis, both frontalin andexo brevicomin share the same receptors on the antennae. The results indicated that the terpene hydrocarbons share some, but not all, of the same receptors.
TL;DR: In this article, the deformation of a thin thread of viscous liquid (viscida) as its ends are slowly moved together is considered and a numerical description of the motion of the thread is derived.
Abstract: We consider the deformation of a thin thread of viscous liquid (viscida) as its ends are slowly moved together. Equations are deduced which are capable of describing the motion of the thread when the displacement of the axis from a straight line is either on the scale of the thread thickness (problem 1) or on the much larger scale of the thread length (problem 2). In the former case it is shown analytically that an arbitrary initial displacement evolves in such a way that, as the appropriately scaled time τ becomes large, the first mode of the disturbance emerges in a dominant role with an amplitude that is proportional to τ½ and independent of the initial amplitude. This provides the initial condition for problem 2, for which a numerical description is obtained.In addition, we analyse the situation when the ends of the viscida are slowly pulled apart. In this case the high frequency end of the spectrum dominates as an arbitrary disturbance decays.
01 Jan 1975
TL;DR: This paper examined public offenders' generalized expectancies of control as they relate to length of time in prison and behavior within the institution, in order to demonstrate the usefulness of a multidimensional modification of Rotter's locus of control scale with a prison sample.
Abstract: This study examined public offenders' generalized expectancies of control as they relate to length of time in prison and behavior within the institution, in order to demonstrate the usefulness of a multidimensional modification of Rotter's locus of control scale with a prison sample. Inmates (N= 145) serving sentences in a large, state prison responded to three locus of control scales designed to measure separately expectancies of internality, of control by powerful others, and of control by chance forces. It was reasoned that if the separation of control into these three orientations is meaningful, then changes in perceptions of control by powerful others should be particularly relevant to the prison experience. As predicted, scores on the Powerful Others scale were significantly related to length of time in prison and number of times punished by solitary confinement.
TL;DR: Data from a series of concentrations of ethylene on elongation, diameter, and geotropism of the stems and roots of etiolated seedlings are indicative of more than one primary mechanism for ethylene action in plants.
Abstract: The effects of a series of concentrations of ethylene (10, 20, 40, to 10,240 nl/l) on elongation, diameter, and geotropism of the stems and roots of etiolated seedlings of Pisum sativum L., Arachis hypogea L., Phaseolus vulgaris L., and Gossypium hirsutum L. were measured or observed. Of the 24 possible responses, 4 were unaffected at the concentrations used, 5 were affected slightly, and the remaining responses exhibited a 14-fold range of apparent half-maximum concentration dependencies (i.e. 95 nl/l for the effect on pea epicotyl geotropism to 1350 nl/l for the promotion of cotton hypocotyl diameter). Six or possibly eight of these responses appear to have the same concentration dependencies while the others fell in pairs or as individual responses. The data, if interpreted in a manner analogous to enzyme kinetics, are indicative of more than one primary mechanism for ethylene action in plants.
TL;DR: Sunflowers (Helianthus annus L.) is one of the world's leading oilseed crops as mentioned in this paper and is used as a cooking oil or in salad oils and margarine.
Abstract: Sunflowers (Helianthus annus L.) is one of the world's leading oilseed crops. Sunflower oil ranks second only to soybean oil in world vegetable oil production. Its high ratio of polyunsaturated fatty acids and its good stability characteristics make sunflower oil highly attractive for use as a cooking oil or in salad oils and margarine. Whole sunflower kernels and high protein sunflower meal can be incorporated into human food formulations. Topics of interest in the review will be the development of the sunflower crop in the United States, seed structure and composition, processing of the seed into oil and meal products, and marketing potential. Also, a review will be made of research on confectionery sunflowers and on the use of sunflower oil and meal in food products.
TL;DR: Fatty acid composition of seed oil was investigated in groundnut cultivars grown at 7 sites in Texas, Florida, Georgia, Oklahoma and Virginia, USA and suggested that cv.
Abstract: Fatty acid composition of seed oil was investigated in 10 groundnut cultivars grown at 7 sites in Texas, Florida, Georgia, Oklahoma and Virginia, USA. The data suggested that cv. F 439-16-6, Wilco I, Florunner, Va 72R and Florigiant were more sensitive to environmental temperatures than Spanish-type cultivars. Large-seeded Virginia-type cultivars were highly sensitive to environment.
TL;DR: Efforts to minimize the severity of these problems have resulted in methodological inquiries covering a wide range of variables, but less attention has centered on whether two or more simultaneously applied variables significantly interact in their effects on any of the above problems.
Abstract: Efforts to minimize the severity of these problems have resulted in methodological inquiries covering a wide range of variables. Most studies have tested the effectiveness of certain variables in minimizing the nonresponse problem [1, 5, 6, 7, 8]. A fewer number have extended the analysis to test the effectiveness of similar variables in minimizing item omission and response slowness [2, 4]. Even less attention has centered on whether two or more simultaneously applied variables significantly interact in their effects on any of the above problems.