Abstract: Frugivory by extinct horses, gomphotheres, ground sloths, and other Pleistocene megafauna offers a key to understanding certain plant reproductive traits in Central American lowland forests. When over 15 genera of Central American large herbivores became extinct roughly 10,000 years ago, seed dispersal and subsequent distributions of many plant species were altered. Introduction of horses and cattle may have in part restored the local ranges of such trees as jicaro ( Crescentia alata ) and guanacaste ( Enterolobium cyclocarpum ) that had large mammals as dispersal agents. Plant distributions in neotropical forest and grassland mixes that are moderately and patchily browsed by free-ranging livestock may be more like those before megafaunal extinction than were those present at the time of Spanish conquest.

Abstract: The shuttle imaging radar (SIR-A) carried on the space shuttle Columbia in November 1981 penetrated the extremely dry Selima Sand Sheet, dunes, and drift sand of the eastern Sahara, revealing previously unknown buried valleys, geologic structures, and possible Stone Age occupation sites. Radar responses from bedrock and gravel surfaces beneath windblown sand several centimeters to possibly meters thick delineate sand- and alluvium-filled valleys, some nearly as wide as the Nile Valley and perhaps as old as middle Tertiary. The now-vanished major river systems that carved these large valleys probably accomplished most of the erosional stripping of this extraordinarily flat, hyperarid region. Underfit and incised dry wadis, many superimposed on the large valleys, represent erosion by intermittent running water, probably during Quaternary pluvials. Stone Age artifacts associated with soils in the alluvium suggest that areas near the wadis may have been sites of early human occupation. The presence of old drainage networks beneath the sand sheet provides a geologic explanation for the locations of many playas and present-day oases which have been centers of episodic human habitation. Radar penetration of dry sand and soils varies with the wavelength of the incident signals (24 centimeters for the SIR-A system), incidence angle, and the electrical properties of the materials, which are largely determined by moisture content. The calculated depth of radar penetration of dry sand and granules, based on laboratory measurements of the electrical properties of samples from the Selima Sand Sheet, is at least 5 meters. Recent (September 1982) field studies in Egypt verified SIR-A signal penetration depths of at least 1 meter in the Selima Sand Sheet and in drift sand and 2 or more meters in sand dunes.

Abstract: Functional and electrophoretic properties of the seed flour and a protein concentrate prepared by alkaline extraction from lupin seeds (Lupinus mutabilis, cultivar H-6) were investigated. SDS-PAGE indicated presence of 13 and 12 subunits in the seed flour proteins and the protein concentrate, respectively. Lupin protein concentrate had good water and oil absorption and gelation properties. Solubility of lupin proteins was minimum at a pH of 4.0 but increased rapidly beyond pH 5.0. Foaming capacity of the protein concentrate could be improved by increasing concentration as well as by adding NaCl and was influenced by pH and incorporation of certain carbohydrates. Emulsion properties of lupin proteins were concentration and pH dependent. Moist heat improved the in vitro digestibility of the seed proteins. The seed flour as well as the protein concentrate did not have detectable trypsin, chymotrypsin, and α-amylase inhibitory activities.

Abstract: The distribution of compositional types among the asteroids is found to vary systematically with heliocentric distance. Seven distinct peaks in the relative proportion of the compositional types E, R, S, M, F, C, P, and D are found from 1.8 to 5.2 astronomical units. The inferred composition of the asteroids in each semimajor axis region is consistent with the theory that the asteroids accreted from the solar nebula at or near their present locations.

Abstract: Expressions in the Icon programming language may be conditional, possibly producing no result, or they may be generators, possibly producing a sequence of results. Generators, coupled with a goaldirected evaluation mechanism, provide a concise method for expressing many complex computations. This paper describes the evaluation of expressions in Icon and presents an Icon program that explicates the semantics of expression evaluation. This program also provides an executable \"formalism\" that can be used as a tool to design and test changes and additions to the language.

Abstract: The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

Abstract: A protein concentrate (71.45% protein on a dry weight basis) was prepared from winged bean [Psophocarpus tetragonolobus (L.) DC] seeds. Solubility of the protein concentrate was minimal at a pH of 4.0. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the bean flour proteins and protein concentrate indicated 9 subunits each, with apparent molecular weight ranges of 27,000–380,000 and 14,200–143,000 daltons, respectively. Least gelation concentrations and water and oil absorption capacities of the seed flour and the protein concentrate were determined. Emulsion and foaming properties of the protein concentrate were investigated. Effect of moist heat on seed protein digestibility was assessed in vitro. Protein concentrate had lower tannins and trypsin, chymotrypsin, and α-amylase inhibitory activities compared to bean flour.

Abstract: We consider two interpretations for what it means for test data to demonstrate correctness. For each interpretation, we examine under what conditions data sufficient to demonstrate correctness exists, and whether it can be automatically detected and/or generated. We establish the relation between these questions and the problem of deciding equivalence of two programs.

Abstract: A clear correlation between the presence of stomata on both surfaces and factors such as habitat, growth form, and physiology has yet to emerge in the literature. However, certain loose trends with these factors are evident, and these are reviewed along with evidence for hypostomaty as the primitive form. It is proposed that the effect of developing stomata on the upper surface as well as the lower is to increase maximum leaf conductance to CO2. Plants with a high photosynthetic capacity, living in full-sun environments, and experiencing rapidly fluctuating or continuously available soil water (as opposed to seasonal or long-term soil water depletion), are identified as deriving an adaptive advantage from a high maximum leaf conductance. The correlation between groups of plants fitting the above conditions and those noted to be amphistomatic is remarkable. Plants not fitting the conditions are found to be largely hypostomatic.

Abstract: This study was designed to assess the accuracy and problems of noninvasively measuring right and left cardiac output by range-gated pulsed Doppler echocardiography. Sixteen children with cardiac disease, aged 3 months to 17 years, served as the subjects; 2-dimensional range-gated pulsed Doppler echocardiographic data were unobtainable in 2 children, leaving 14 for study. Diagnoses included shunt lesions, valvular abnormalities, coarctation, repaired defects, and Kawasaki's disease. The equipment for this study included a 2-dimensional echocardiographic Doppler sample volume locator. The Doppler frequency shift was analyzed by fast Fourier transform. Twenty 2-dimensional range-gated pulsed Doppler echocardiographic measurements (10 pulmonary and 10 aortic) were made simultaneously with indicator dilution outputs or angiographic outputs. In 4 subjects, 2-dimensional range-gated pulsed Doppler echocardiographic aortic outputs were not possible. For this study, vessel diameter was determined by both echocardiography and angiography, Doppler intercept angle by 2-dimensional echocardiography, and velocity by 2-dimensional range-gated pulsed Doppler echocardiography. Comparison of cardiac output measurements obtained by invasive methods and by 2-dimensional range-gated pulsed Doppler echocardiography (angiographic vessel measurement) showed a correlation of +0.94 (standard error of the estimate [SEE] = 0.53) with a slope of y = 0.83 × + 0.61, indicating that the slope and line of identity were almost equal and the offset from 0 was small. For 2-dimensional range-gated pulsed Doppler echocardiography (echocardiographic vessel measurement), the correlation was +0.94 for aortic flow but only +0.72 for pulmonary flow. Problems encountered in some patients included turbulence, which made velocity measurements unreliable, difficulty in obtaining aortic flow by Doppler echocardiography due to transducer configuration, and measurement of pulmonary diameter by echocardiography. The results indicate that 2-dimensional range-gated pulsed Doppler echocardiographic outputs are accurate under conditions of nonturbulent or minimally turbulent flow and adequate imaging, but only when vessel diameter can be accurately measured.

Abstract: INTRODUCTION Economics has tended to be long on theories (Hypotheses) and the use of “logical completeness” as a criterion for judging the value of a theory, but short on technologies for discriminating among theories on the basis of rigorous standards of empirical evidence. Consequently, the body of theory in economics tends to grow from a steady stream of additions, with replacements occurring only occasionally. It is sometimes claimed that our methodology is limited by the fact that economics is complicated and we cannot do experiments, with the result that logical completeness becomes a crucially important test criteria. Caricaturized, it is as if economics had tried to do the work of classical physics by a shortcut that bypassed Galileo and Kepler and started “at the top” with the intellectually more interesting methods of Isaac Newton. The consequences of this confusion of form with substance would be of less import were it not for the fact that as “experts” we have made, or fellow-traveled with, policy prescriptions requiring us to know more than indeed we can demonstrate that we know. This professional process seems to have led us to believe that our Keynesian prescriptions could fine-tune the economy, that regulation would solve the alleged monopoly problem, and that coercive action was implied ipso facto by the untested theorem that market institutions will “fail” in the presence of externality and public goods.

Abstract: Suicide occurs in a cultural context, but that context, especially in terms of community attitudes, has not been explored fully. This study presents a 100-item questionnaire (the Suicide Opinion Questionnaire; SOQ) and a factor analysis of 285 respondents. The results, 15 factors that accounted for 76.6% of the total variance, underscore the complexities of such attitudes.

Abstract: Combined analysis of helium (584 A) airglow and the atmospheric occultations of the star delta Scorpii imply a vertical mixing parameter in Saturn's upper atmosphere of K (eddy diffusion coefficient) of approximately 8 x 10 to the 7th sq cm per second, an order of magnitude more vigorous than mixing in Jupiter's upper atmosphere. Atmospheric H2 band absorption of starlight yields a preliminary temperature of 400 K in the exosphere and a temperature near the homopause of 200 K. Certain auroral emissions can be fully explained in terms of electron impact on H2, and auroral morphology suggests a link between the aurora and the Saturn kilometric radiation. Absolute optical depths have been determined for the entire C ring and parts of the A and B rings. A new eccentric ringlet has been detected in the C ring. The extreme ultraviolet reflectance of the rings is fairly uniform at 3.5 to 5 percent. Collisions may control the distribution of H in Titan's H torus, which has a total vertical extent of about 14 Saturn radii normal to the orbit plane.

Abstract: Recombinant plasmids containing cDNA inserts from human leukocyte interferon (IFN-α), fibroblast interferon (IFN-β), or immune interferon (INF-γ) genes were radiolabeled and hybridized in situ to human metaphase chromosome preparations. The results localized the human IFN-α and IFN-β genes to the short arm of chromosome 9(p21→pter) and localized the IFN-γ gene to the long arm of chromosome 12(q24.1).

Abstract: Recent excavations at the deeply stratified Late Pleistocene cave site of Tabun on Mount Carmel have, yielded a long sequence of Middle and Lower Paleolithic industries and associated geological and environmental evidence that has important implications for the understanding of man's cultural and biological development in that period. An analysis of these materials strongly supports a continuity in cultural development at this site from about 130,000 to 50,000 years ago and suggests that a continuous biological evolution from Neandeithal to anatomically modem Homo sapiens took place in the southern Levant.

Abstract: We examined the role of dietary electrolytes and humoral factors in causing seasonal changes in blood pressure. Normal subjects had no seasonal difference in blood pressure, although urinary sodium and norepinephrine were significantly higher in winter than in summer. In patients with essential hypertension blood pressure, urinary sodium and norepinephrine excretion and plasma norepinephrine concentration were significantly higher in winter. Plasma renin activity, plasma and urinary aldosterone and urinary kallikrein excretion were not significantly different between the two seasons in both normal subjects and hypertensive patients. In conclusions, the blood pressure of patients with essential hypertension has a seasonal variation with higher pressures in the winter than in the summer. Increased sympathetic nervous activity and an increased load of sodium presented to the kidney for excretion may be contributing factors in the rise in blood pressure in winter in patients with essential hypertension.

Abstract: alpha-Melanocyte-stimulating hormone (alpha-melanotropin; alpha-MSH) is a linear tridecapeptide (Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2) that reversibly darkens amphibian skins by stimulating melanomsome (pigment granule) dispersion within melanophores. By using a number of in vitro melanocyte assays, we have examined the conformational requirements for alpha-MSH activity. Synthesis of [half-Cys4,half-Cys10]-alpha-MSH, a cyclic, conformationally restricted, "isosteric" analogue of alpha-MSH, provided a melanotropin with a potency greater than 10,000 times that of the native hormone in stimulating frog (Rana pipiens) skin darkening. The cyclic analogue also showed substantially prolonged activity relative to the native hormone. [half-Cys4,half-Cys10]-alpha-MSH was approximately 30 times more potent than alpha-MSH in stimulating lizard (Anolis carolinensis) skin melanophores in vitro. By using a cell-free Cloudman S-91 mouse melanoma plasma membrane preparation, we found the cyclic analogue to be approximately 3 times as potent as the native hormone in stimulating adenylate cyclase activity. These results provide insight into the conformational requirements for biological activity of alpha-MSH, and the comparative conformational requirements of alpha-MSH at a number of pigment cell receptors.

Abstract: An isotopic fractionation step between carbon fixed in the leaves and that assimilated into wood cellulose has not previously been included in atmosphere–plant fractionation models. Data presented here, however, show that the magnitude of such a fractionation step may be significant. In an experiment which involved 10 juniper trees from around Arizona, cellulose of leaves was found to be isotopically lighter than that of the corresponding tree rings in all trees by an average of 2‰. In a second experiment, the δ13C of leaf material from a juniper tree sampled at monthly intervals was compared with the δ13C of the corresponding ring. For cellulose, δ13C of the wood varied with changes in δ13C of the leaves and was persistently isotopically heavier by 3–4‰. Furthermore, the observed change in δ13C through the growing season suggests a temperature coefficient of about −0.27‰ °C−1. The direction of this leaf–wood fractionation precludes diffusion processes as the primary cause.