Showing papers by "Louisiana State University published in 1969"
TL;DR: The Ganges and Brahmaputra rivers combined have formed one of the largest deltas in the world, comprising some 23,000 sq. miles as discussed by the authors, and the large discharge and heavy sediment load cause the rivers to be extremely unstable, and the channels are constantly migrating laterally.
1,030 citations
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01 Jan 1969644 citations
TL;DR: Even though control programs which attempt to reduce coronary heart disease by preventing atherosclerosis may meet some success when applied to middle-aged persons, these programs should be directed toward individuals in the twenties and thirties for maximum benefits.
236 citations
TL;DR: Subterranean foraging galleries of a colony of C. formosanus Shiraki were excavated in a filled, swampy area about 2 miles west of Lake Charles and it was apparent that this gallery system was less than 10 years old.
Abstract: Subterranean foraging galleries of a colony of C. formosanus Shiraki (Isoptera: Rhinotermitidae) were excavated in a filled, swampy area about 2 miles west of Lake Charles. Branches from 3 main galleries radiating from a dead baldcypress tree ramified over about 1.4 acres. These galleries were connected with food sources more than 200 feet from the original starting point. Species of trees attacked included dead baldcypress, dead pine, live wax myrtle, and live Chinese tallow. Live pine was not attacked by this termite. Most of the galleries were lined with carton material that varied in thickness and the galleries ranged from 2 to 46 inches deep. Vertical galleries branched from horizontal galleries and extended to the water table. A subterranean carton nest that contained 6 supplementary queens was found 19 inches below the soil surface and 25 feet from the nearest food source. Based on the date the swampy area was filled, it was apparent that this gallery system was less than 10 years old.
123 citations
TL;DR: In this paper, the population statistics for Cl, Br, I, HCO 3, SO 4, Na, Ca, Mg, K, Rb, Li, Sr, Mn, Zn, Fe, Ni, Co, Cr and Cu are presented, together with weighted, mean composition.
103 citations
TL;DR: The structural data of several nickel-rich rare earth-nickel phases are reported in this article, where three modifications are encountered for Nd2Ni7 and three modifications were encountered for the high-temperature forms.
Abstract: The structural data of several nickel-rich rare earth-nickel phases are reported. Excepting CeNi3, the other LnNi3-phases crystallize with the PuNi3-type structure. Both the Ce2Ni7- and Gd2Co7-type structures occur in several Ln2Ni7-phases. Ce2Ni7 possesses only the Ce2Ni7-type structure. Three modifications are encountered for Nd2Ni7. The low-temperature form is of the Ce2Ni7-type. The high-temperature forms are found to possess large periodicities along the c0-direction. Nd2Ni17 has the Th2Ni17-type structure at high temperatures.
100 citations
TL;DR: An electron microscope study of developing mouse oocytes has revealed a close morphological relationship between mitochondria and endoplasmic reticulum, and the functional significance of these observations are discussed in relation to biochemical studies which demonstrate a transfer of protein from endoplASM to mitochondria.
Abstract: An electron microscope study of developing mouse oocytes has revealed a close morphological relationship between mitochondria and endoplasmic reticulum. In many instances, it was noted that the outer mitochondrial membrane was continuous with the reticular membranes. These cytoplasmic membranes are smooth or studded with ribosomes. These continuities establish an open channel between the endoplasmic reticulum and mitochondria. Similar connections are also found in isolated preparations of mitochondria from the adult guinea pig ovary. The functional significance of these observations are discussed in relation to biochemical studies which demonstrate a transfer of protein from endoplasmic reticulum to mitochondria.
95 citations
TL;DR: A cellobiose-utilizing bacterium isolated from sugar cane bagasse and identified as a strain of Alcaligenes faecalis produced an inducible β-glucoside-splitting enzyme, which had a wide pH range and had its specificity on β- glucosidic linkage and the rate of hydrolisis of glucosides depended upon the nature of the aglycon moiety.
Abstract: A cellobiose-utilizing bacterium isolated from sugar cane bagasse and identified as a strain of Alcaligenes faecalis (ATCC 21400) produced an inducible β-glucoside-splitting enzyme. The enzyme was purified by a series of streptomycin and ammonium sulfate fractionations and by Sephadex and diethylaminoethyl column chromatography. The final preparation was purified 130-fold, with a recovery of about 10% of the initial enzyme activity. The enzyme had a wide pH range, with optimal activity at pH 6.0 to 7.0. The enzyme was stable in solution at pH 6.5 to 7.8 when kept at 30 C for 2 hr, but it was destroyed by temperatures above 55 C. At 58 and 60 C, the time required to inactivate 90% of the initial activity was 16 and 6.5 min, respectively. An activation energy of 9,500 cal/mole and a Km of 1.25 × 10−4m were obtained by using p-nitrophenyl β-glucoside as a substrate. The Ki value and hydrolysis of cellobiose by the enzyme indicated a high affinity of the enzyme for the cellobiose. The enzyme had its specificity on β-glucosidic linkage and the rate of hydrolisis of glucosides depended upon the nature of the aglycon moiety. The inactivation studies showed the presence of sulfhydryl groups in the enzyme. The activity of the enzyme was easily destroyed by the Cu++ and Hg++ ions. The Michaelis-Menton relationship and the rate of heat inactivation indicated the presence of one type of noninteracting active site in the bacterial β-glucosidase. Molecular weight of the enzyme was estimated by gel filtration (Sephadex G-200) and sucrose density gradient, and a value of 120,000 to 160,000 was obtained.
88 citations
TL;DR: The diurnal variation in responses to prolactin is shown to vary diurnally to offer an explanation for the conflicting and diverse reports regarding the function of prolactIn and emphasize the importance of time in understanding the physiology of Prolactin.
84 citations
TL;DR: It may be, therefore, that intercellular bridges are important for the nourishment and maturation of certain selected oocytes as well as for the synchronization of meiotic events.
Abstract: A fine structural analysis of fetal mouse ovaries reveals the presence of intercellular bridges between developing oocytes. These bridges, which connect two or more oocytes, are most frequently seen prior to the dictyate stage of meiotic prophase. The intercellular connections are limited by a tri-laminar membrane which is continuous with the oocyte plasmalemma. A characteristic feature of all bridges is the presence of an electron-dense material on the cytoplasmic side of the limiting membrane. Since this dense material is a constant and conspicuous component of the entire bridge, identification of these connections is possible in all planes of section. In cross section, the bridges are usually cylindrical, while in longitudinal section, a variety of configurations are observed. Oocytes connected by intercellular bridges exhibit a highly developed Golgi complex which is frequently localized in the region of the cytoplasmic continuities. Vesicular elements, apparently derived from the Golgi, are routinely observed within the boundaries of the bridges. Other cytoplasmic organelles, including rough and smooth endoplasmic reticulum, free ribosomes and mitochondria, are also seen in these bridges. The presence of these vesicles and organelles within intercellular bridges suggests that these connections may provide a means for transfer of organelles and other substances from one oocyte to another. It may be, therefore, that intercellular bridges are important for the nourishment and maturation of certain selected oocytes as well as for the synchronization of meiotic events.
80 citations
TL;DR: The elementary cellulose fibril is a universal structural unit of natural cellulose, similar to that found in cotton, ramie, and jute, studied before.
TL;DR: In this article, the authors present a set of conditions générales d'utilisation of commercial or impression systématique, i.e., the copie ou impression de ce fichier doit contenir la présente mention de copyright.
Abstract: © Publications mathématiques de l’I.H.É.S., 1969, tous droits réservés. L’accès aux archives de la revue « Publications mathématiques de l’I.H.É.S. » (http:// www.ihes.fr/IHES/Publications/Publications.html) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/legal.php). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.
TL;DR: In this paper, the authors found that the time of the diurnal release of pituitary prolactin is an important regulator of seasonal physiological and behavioral conditions in the White-throated Sparrow.
TL;DR: Biochemical evidence supports the hypothesis that the two species diverged during a Pleistocene disjunction of proto-Acris populations in Florida and Mexican refuges and that A crepitans presumably moved from its Mexican refuge northward and northeastward, to become adapted both to grassland and deciduous forest biomes and to attain contact and overlap with A. gryllus in southeastern United States.
Abstract: Population and species structure of the cricket frogs, Acris crepitans and A. gryllus, were examined in terms of protein variation throughout their geographic ranges. Eight hundred and fifty animals, collected from 32 populations in 20 states, were processed to obtain electrophoretic evidence on 20 blood and liver proteins. Molecular data confirm the reproductive isolation of the two species. They had different albumins, transferrins, and hemoglobins; frogs with hybrid protein patterns were not found in regions where the two species are sympatric. Within A. crepitans eight proteins were invariant across the species range; twelve exhibited one or more variant phenotypes. The genetic integrity of the species was illustrated by the uniformity of the albumin, plasma esterases, liver LDH, GOT, GDH, MDH-NADP, NADP-reductase, and hemoglobin polypeptide 4. Its polytypic nature, with geographic divergence into Plains, Delta, and Appalachian groups, was suggested by the presence of specific hemoglobin, transferrin, and liver esterase variants in animals of certain regions. Within-population polymorphism was exhibited by the transferrins, MDH-NAD, and three complexes of liver esterases; heterozygosity was greater in central than in peripheral populations. Biochemical evidence supports the hypothesis that the two species diverged during a Pleistocene disjunction of proto-Acris populations in Florida and Mexican refuges. With the recession of the glaciers, A crepitans presumably moved from its Mexican refuge northward and northeastward, to become adapted both to grassland and deciduous forest biomes and to attain contact and overlap with A. gryllus in southeastern United States.
TL;DR: By placing a thin film of cellophane around the enzyme gel layer to prevent leaching of urease into the surrounding solution, an electrode could be used continuously for over 21 days at 25[ddot]C with no loss of activity.
Abstract: The enzyme urease was immobilized in a layer of acrylamide polymer on the surface of a Beckman cationic electrode sensitive to ammonium ion. The substrate urea diffuses to the enzyme electrode and reacts with the immobilized enzyme to produce ammonium ion at the surface of the glass electrode. By placing a thin film of cellophane around the enzyme gel layer to prevent leaching of urease into the surrounding solution, an electrode could be used continuously for over 21 days at 25[ddot]C with no loss of activity.
TL;DR: The n.m. spectra of sucrose octaacetate, 1-kestose hendecaacetane (2), and nystose tetradecaacetate (3) were measured in benzene-d6, chloroform-d, and acetone-d 6, at 100 and 220 MHz as mentioned in this paper.
TL;DR: In this article, the decay rate of a polarized neutron source in a constant, uniform magnetic field of arbitrary strength was calculated and it was shown that the magnetic field is of order 10 − 13 G or larger.
Abstract: The $\ensuremath{\beta}$-decay rate of a polarized neutron source in a constant, uniform magnetic field of arbitrary strength is calculated. We show that the decay rate is substantially changed if the magnetic field is of order ${10}^{13}$ G or larger. Fields of such strength have been speculated to exist in the early universe or in neutron stars.
TL;DR: In this article, five types of carbonate breccia are recognized in the Chiantla quadrangle of northwestern Guatemala and they are distinguished by similarity in lithology between clasts and matrix, highly irregular clast shapes, and a complete graduation in grain size from micrite in the clasts to sparry calcite in the matrix.
Abstract: Five types of carbonate breccia are recognized in the Chiantla quadrangle of northwestern Guatemala. Depositional breccias and conglomerates (lithoclastic limestones) are widespread in the Cretaceous Ixcoy limestone and attain thicknesses up to 500 m. The lithoclasts were eroded from adjacent emergent areas, which probably resulted from faulting. Depositional breccias are recognized by the presence of primary sedimentary structures, original lime-mud matrix, and polymictic clasts. A thick sequence (250 m) of evaporite-solution-collapse breccias is present in the lower part of the Ixcoy. These breccias are characterized by dolomite clasts in a matrix of sparry calcite and granulated dolomite. This breccia type is recognized primarily by its close relationship to thick evaporites in the subsurface and neighboring surface exposures. Secondary criteria for their recognition include dedolomite and dedolomitization textures and clasts composed of lithologies compatible with evaporite deposits. Tectonic breccias are formed by extensive fracturing of carbonates during periods of deformation. This breccia type is identified by its proximity to faults; its matrix of either coarse-crystalline, sparry calcite or granulated carbonate material; and oligomictic clasts with matching edges. Caliche breccias have formed by caliche cementation of carbonate rubble at the base of slopes, and by the development of caliche veins transecting dolomitic rocks. Pseudobreccias, which form by selective grain growth, occur locally in limestones of the Ixcoy. They are distinguished by similarity in lithology between “clasts” and “matrix,” highly irregular “clast”-shapes, and by a complete graduation in grain size from micrite in the “clasts” to sparry calcite in the “matrix.” These breccias, though similar in the field, may be distinguished by a combination of stratigraphic and petrographic criteria.
TL;DR: Spiders were found to be more closely associated with percent egg predation than ants, and numbers of predators and percentages of hatchability had a more significant effect on percentages of larval recovery than numbers of sugarcane plants per stool.
Abstract: Field experiments were conducted during 1966 and 1967 in the Bayou Sec area of Assumption Parish near Napoleonville, La., to (1) evaluate, quantitatively, the relative importance of arthropod predators of Diatraea saccharalis (F.) by correlation between numbers of these predators and the degree of egg and larval mortality of the borers; (2) obtain qualitative evidence of predation through frequent and widespread field observations; and (3) study the feeding behavior and habits of the predators concerned. Average percent egg predation was higher during August and September than during June and July. Percent eggs destroyed by sucking predators was significantly higher than those destroyed by chewing predators. More predation was recorded during the night than during the day. Positive correlation coefficients were found between total numbers of predators (ant and spider populations) and percent egg predation. Spiders were found to be more closely associated with percent egg predation than ants. Percent recovery of sugarcane borer larvae was significantly higher in July than in June. Numbers of predators and percentages of hatchability had a more significant effect on percentages of larval recovery than numbers of sugarcane plants per stool. Predators that were observed feeding on the different stages of the sugarcane borer belong to the following taxa: Formicidae, Carabidae, Forficulidae, Elateridae, Chrysopidae, and Araneida.
TL;DR: The dietary and cleansing procedures per se were without effect on quantitative bacterial flora of individuals undergoing mechanical cleansing such as a patient might pursue at home prior to elective colonic surgery, which suggests that changes in flora per gram of feces occurring during intestinal antisepsis are due solely to the antibiotic employed.
TL;DR: The defects of cupferron and versatility of N-benzoyl-N-phenylhydroxylamine in reaction with various metal ions is discussed and suggestions for further use of this compound and other hydroxylamines are given.
TL;DR: The presence of five different β-glucanases has been investigated in coleoptiles of Avena with the use of specific substrates and it is suggested that the enzymes are present in particulate form.
TL;DR: In this article, the 1C (d)-Ribopyranose tetraacetate was shown to exist, in acetone-d 6 at room temperature, as a 9:11 mixture of 1C(d) and C1(d ) conformers in rapid equilibrium.
TL;DR: In this article, the chemical characteristics of Holocene sedimentary accumulations and some of the diagenetic products formed after deposition were studied, providing clues to the history of shale beds and contributes to the understanding of the effects of overburden on compaction, dewatering, and increase in compressive strength with depth of burial.
Abstract: Studying the chemical characteristics of Holocene sedimentary accumulations and some of the diagenetic products formed after deposition provides some clues to the history of shale beds and contributes to the understanding of the effects of overburden on compaction, dewatering, and increase in compressive strength with depth of burial. X-ray radiography was utilized extensively in examining core slabs from a fresh-water clay sequence in the Atchafalaya River Basin. From the radiographs, detailed diagenetic features such as cementation by secondary precipitated minerals, pyrite and carbonate replacement of organic fragments, and progressive formation of nodules were revealed. Selected samples were analyzed for various chemical and mineralogical constituents by means of differential thermal analysis, X-ray diffraction, X-ray fluorescence, atomic absorption spectrophotometry, Kjeldahl method for total nitrogen and wet combustion for organic carbon. The results indicated the presence of various cementing agents. The diagenetic mineral accumulations consisted of CaCO 3 , Fe 2 O 3 , FeCO 3 , and Mg and Mn compounds of unknown nature and have contributed significantly to the observed strength increase with depth. The dewatering process, commonly attributed solely to compaction resulting from overburden, may also be brought about by a gradual replacement of the pore-water space by secondary mineral accumulation. Numerous processes are responsible for the initial mineral accumulations and chemical reactions, especially of soluble organic compounds.
TL;DR: Acherman et al. as discussed by the authors found no beneficial effects from increasing the choline level of the diets used in their experiments, and Nesheim et.al. found no benefit from adding choline to the diet of laying hens.
TL;DR: It may be hypothesized that endogenous prolactin exerts an antigonadal effect in the migratory white-throated sparrow that delays reproductive maturation until the birds reach their breeding grounds.
TL;DR: Low level mercaptoethanol (ME) — sensitive (IgM) anti-KLH hemagglutinating antibody coincided with appearance of delayed skin reactions early in the course of the study and was followed sequentially by wheal and flare skin reactivity and IgG hemag GLUTinating antibody.
TL;DR: In this article, a method was described for the determination of trace amounts of phosphorus, arsenic or silicon by atomic absorption spectrometry, and the heteropoly-molybdo acids were formed and selectively separated by means of solvent extraction.