Este trabajo analiza el marco teórico de diferentes modelos de organización del riego y los aplica al caso de la Corporación de Fomento del Río Colorado (CORFO) en la provincia de Buenos Aires, Argentina. Al ser el riego en el Valle del Rio Colorado, un recurso estratégico, se presentan enfoques aplicables desde el punto de vista teórico y se busca la modalidad más adecuada de llevarlos a su aplicación en un contexto real o bien, que nos orienten a comprender el funcionamiento de mecanismos que se presentan en esta zona de riego. Se incorpora el concepto de cuenca en el análisis, para poder dimensionar que la zona de riego comprende, no solo a las personas e instituciones involucradas con los regadíos, sino a todos los demás agentes sociales que indirectamente reciben los costos y beneficios de este recurso, así como las poblaciones que están localizadas dentro de la misma. Esta idea de análisis, lleva a entender la forma de pensar y comportarse de la gente que vive en dicha cuenca y además se presenta un fenómeno migratorio dado por la modalidad de contratación y laboreo característico de los cultivos hortícolas. Se presentan distintas formas de organización, en la gestión de regadíos, lo cual depende si al agua se la considera un bien público o un bien que puede ser un objeto de mercado. Ambas posturas buscan hacer más eficiente su asignación como recurso escaso. Para elegir una figura en la cual centrar el análisis, identificamos a la Corporación de Fomento del Río Colorado (CORFO), además de ser la autoridad del agua, es la receptora del agua para riego, proveniente del Rio Colorado y de allí se encarga de distribuirla en los tres canales primarios, los cuales van a los canales secundarios para terminar en cada uno de los regantes. La motivación que llevó a abordar esta temática, está dada por un lado por mi formación y experiencia profesional como administrador y por el otro que conozco como regante de una explotación de mi propiedad, en esta zona bajo riego. Esta confluencia permite abordar la problemática desde una visión pragmática, sin descuidar la posibilidad de encuadrarnos en la teoría de la administración. Y esto último fue el desafío: tamizar el conocimiento científico y poderlo verificar en la experiencia en los regadíos.

Gold, silver and base metal-rich minerals of the North Amethyst vein occupy fractures in 26 Ma volcanic rocks near the southern margin of the San Luis caldera, at the northern edge of the Creede district, San Juan Mountains, Colorado. The veins contain two associations of mineral assemblages that are separated locally by breccias and sediments. The earlier, fine-grained association consists of quartz, rhodonite, Mn-carbonates, hematite, magnetite, electrum, Au-Ag-sulfides, Ag-sulfosalts, and base metal sulfides. The second association consists of coarser-grained quartz, calcite, sericite, chlorite, hematite, adularia, fluorite, base metal sulfides, and Ag-tetrahedrite. The first association (fluid boiling at >350°C to 270°C, <2 wt% HaCl equiv.) has a calculated depth of >1000m; the second association (nonboiling, basemetal assemblages: 280°C to 220°C, 5-11 wt%; boiling, quartz + fluorite + calcite: 270-220°C, 0-4.5 wt%) may have formed at -500 meters. Deeper estimates from geologic reconstruction (-1500m) support minera1ogial evidence that CO₂ played a role in mineral deposition. The second association also may have formed much later in time than the Au-rich stages, perhaps after extensive erosion. Adularia of the second association has an age of 25.13 Ma (M. Lanphere, pers. commun., 1987). Paragenetically early Au-rich North Amethyst galenas have lead isotopic compositions that are less radiogenic than galenas that formed later, as part of the second association. Galenas from central and southern Creede veins overlap compositions of galenas from the later North Amethyst association. Alpha-Corsair vein galenas are isotopically similar to North Amethyst Au-stage galenas. All galenas are isotopically more radiogenic than host volcanics and probably derived their lead compositions from both Precambrian basement and Tertiary volcanics or their equivalents. The first association (Mn-Au) is absent in the southern and central Creede district, whereas, the second association correlates with assemblages of the southern and central district. The local and early occurrence of the Mn-Au assemblages may indicate that they formed in a localized hydrothermal system that predated the extensive hydrothermal system from which ores of the central and southern Creede district are proposed to have been deposited. Least radiogenic and paragenetically early mineral assemblages bold the most promise for gold exploration in the central San Juan area. / Ph. D.

The purpose of this study was to determine whether local and tourist boaters in the Arkansas River Headwaters Recreation Area differed in their activities, perceptions of environmental problems and user conflicts, and preferences for management. Locals were defined as living 100 miles or less from the river, and tourists were those living more than 100 miles away. Data were collected by on-site interviews with boaters as they completed their trip, and through a 12-page mailback questionnaire. Approximately 1168 questionnaires were returned, for an overall response rate of 58%. Few differences were found between locals and tourists. The largest differences between the two groups were in their trip expenditures and in their recreational activities in the river valley. Expenditures by tourists were significantly greater, and tourists also showed a greater tendency to both participate in and express interest in a greater variety of activities than did locals. The locals tended to be slightly more experienced and involved than were tourists, and they were also more predisposed toward membership in river running clubs. On reasons for selecting the Arkansas River, locals were more inclined to feel that a convenient location and being with friends were more important, while tourists felt that being in a new area with a variety of recreational opportunities was more important. In addition, locals exhibited a slightly greater sensitivity toward both environmental and people problems along the river. However, neither group supported more controls to reduce environmental damage or user conflicts. With respect to services and facilities, differences between the two groups were tenuous. Tourists were slightly more supportive of both manipulating the river's water level to benefit boating and constructing more shower facilities along the river. Locals were more in favor of scheduling 'no boat' times on the river to benefit fishing. Finally, in response to willingness to pay for services, tourists were more inclined to pay a greater amount for a given service than were locals in four out of five responses. Results of this study indicate that managers need to be aware of and monitor the perceptions, opinions, and preferences of both local and tourist users. Additionally, user groups other than boaters (such as landowners, river fishermen, or wildlife observers) must be studied in order that a more complete and thorough understanding of the different resource users and their relationships with the resource can be attained. / Master of Science

The anther culture response of diploid Solanum chacoense (chc) - S. phureja (phu) hybrids and the regeneration potential of anther-derived monoploids was evaluated. In vivo evaluation of interspecific hybrids was also performed. Three hybrids were anther cultured to observe the effects of reduced nitrogen source on androgenesis. Anthers were distributed to five reduced nitrogen sources. The N concentration was 30 mM. No tested reduced nitrogen source proved superior to the control. Genotype significantly affected embryo production. Eleven monoploid genotypes were included in a leaf disc regeneration procedure utilizing three separate transfers to fresh medium differing by growth regulator composition; six genotypes responded. Silver thiosulfate (STS) at either of two steps in the process proved detrimental to diploid recovery. Hybrids between phu and chc involving six phu clones and eight chc clones or accessions, all resistant to Colorado potato beetle (CPB), were used. No inter-family differences for germination, fruit/pollination, or seed/fruit were observed. Substantial mortality, ascribed to the phenomenon of “hybrid breakdown”, occurred in three families by month four of the study. Field plantings revealed adequate CPB resistance, while Ambush (147 g/ha) application increased total tuber weight per plant and average tuber weight. Hybrids produced less total tuber weight than S. tuberosum (tbr), while chc genotypes produced the smallest average tuber size. Interspecific hybrids produced tuber sizes intermediate between chc and phu. Tbr tubers were the largest. Chc families, regardless of selection for leptine glycolakaloids, suffered the least CPB damage and phu parental clones and hybrid families suffered the most. / Master of Science

The gem pegmatites of Mt. Antero, Colorado occur in an Oligocene granitic stock containing aquamarine, smoky, clear and milky quartz, phenakite, muscovite, fluorite, garnet, pyrite, topaz and calcite. Aquamarine and smoky quartz contain abundant primary fluid inclusions outlining growth zones, as well as numerous trails of pseudosecondary and secondary inclusions. Salinities and homogenization temperatures (Th) of these inclusions define five distinct groups. The earliest primary fluid inclusions occur in outer growth zones of gem aquamarines. These inclusions have salinities of 2.6 - 3.9 wt.% and homogenize at 350°- 360°C. The earliest primary inclusions in smoky quartz have salinities of 5.0 - 5.6 wt. % and homogenize at the same temperature as the primaries in aquamarines. Paragenetically later primary and secondary C02-bearing inclusions in aquamarine, and secondary C02- bearing inclusions in smoky quartz homogenize at 350°-360°C. Later secondary inclusions in smoky quartz define two distinct groups based on salinity and Th (Group 1: Th = 285°-355°C, salinity = 6.1 - 7.9 wt.%; Group 2: Th = 215°-245°C, salinity = 3.0- 4.3 wt.%). Salinities and Th's of very latest primary inclusions in aquamarine overlap with those of group 1 in smoky quartz. Homogenization temperature of latest primary inclusions in smoky quartz is 194°-213°C and salinities range from 0.5 - 2.0 wt.%. Secondary inclusions in phenakite and fluorite crystals homogenize at about 270°C and 215°C, and have salinities of 1.3 and 0.5 wt. %, respectively. The fluid inclusion data, combined with constraints from mineral equilibria, suggest that gem aquamarines formed at approximately 500° to 600°C and - 1 kbar from low to moderate salinity aqueous fluids (2.6 - 6.2 wt. %). The salinity increased during the final stages of aquamarine growth and initial stages of smoky quartz formation, reaching a maximum of about 8 wt. %. During later stages of smoky quartz formation and subsequent fluorite and phenakite growth the salinity continuously decreased. Calcite and the latest quartz crystallized from -0.5 wt. % solutions. The beryl crystals from Mt. Antero vary in color from dark to pale blue aquamarines to the essentially colorless goshenite variety with some individual crystals showing color zoning. Quantitative electron microprobe analyses showed that iron, which imparts the blue color to the aquamarines, is enriched in the dark blue parts of a gem crystal and comparatively depleted in the paler blue terminated parts of the crystals. Most of the aquamarine crystals showed evidence of growth zoning. Quantitative analyses and X-ray maps generated with electron microprobe show that iron and cesium are depleted in the cores of the beryls and enriched in the rims of the crystals. An exact opposite trend is observed for sodium and magnesium, which are depleted in the rims but enriched in the cores of the beryls. / Master of Science

Within-field variation in mortality of Colorado potato beetle, Leptinotarsa decemlineata (Say), in a filter-paper insecticide bioassay was determined in three Virginia potato fields in 1989 and five fields in 1990. Bioassays were performed for each of three different insecticides on Colorado potato beetle larvae collected from 12-16 different locations (equal sized blocks) per field. Comparisons of 95% mortality confidence intervals between all block combinations per field indicated that field size had no influence on variation in Colorado potato beetle mortality in the bioassay. No apparent relationship existed between the level of Colorado potato beetle insecticide susceptibility (LC₉₀ value) and percentage of mortality confidence interval overlap among field blocks. Bioassay data from the sample fields indicated that a single bioassay (of potato beetles from one location per field) will yield at least a 0.50 probability (> 0.90 in six of the eight fields) of estimating the mean mortality response (± 5%) of Colorado potato beetle in the entire field. The probability of sampling potato beetles from one location which differed in mean mortality (P ≤ 0.05) from individuals collected in another location within the same field decreased as the number of locations sampled increased (i.e., the probability is 0.12 if three locations are sampled). Filter paper insecticide bioassays were performed on Colorado potato beetles collected from three commercial potato fields to determine the most cost-effective number of bioassay sample units (filter paper disks, 10 larvae per disk). Relative net precision values from three different insecticide bioassays were used as an indication of sample size efficiency, and were based on variation in larval mortality and sample cost. Greatest sample size efficiency in all insecticide bioassays was achieved from a sample of two to five filter paper disk sample units (20-50 total larvae). Additional insecticide bioassays were performed on Colorado potato beetle larvae collected at different times during the potato growing season (from a commercial potato field and from experiment station plots) to determine whether the larval generation sampled or previous insecticide application affected results of the bioassay. Although trends in mortality were not always consistent among first generation larvae sampled on different dates (from insecticide-treated and untreated plots), first generation larvae exhibited significantly (P ≤0.05) greater mortality in the bioassay compared with second generation larvae. Based on these results, we recommend that bioassays to estimate the effectiveness of a particular insecticide against Colorado potato beetle be performed on the target generation immediately before the planned insecticide treatment. PIES (potato insect expert system) is a knowledge-based system for Colorado potato beetle insecticide management in commercial potato fields on the Eastern Shore of Virginia. PIES was written using VP-Expert, a rule-based expert system shell, and uses Colorado potato beetle lifestage, potato growth stage, percent defoliation, and other factors to decide if an insecticide application is necessary to prevent tuber yield loss due to Colorado potato beetle pressure. Field tests at the Eastern Shore Agricultural Experiment Station compared PIES with conventional spray thresholds based on the number of Colorado potato beetles per stem. Tuber yields were not significantly different (P ≤ 0.05) between the two methods, while PIES recommended, on average, 3.7 insecticide applications and conventional thresholds required six insecticide applications. An additional benefit of PIES is that scouting requirements are simpler and quicker than the conventional stem counts. Supercooling points determined for Colorado potato beetle populations from Maine, Washington, and Prince Edward Island, Canada, suggest these populations are freeze-tolerant, that is, they can sustain ice formation within their body fluids. Colorado potato beetles collected from Virginia supercooled at a significantly (P ≤ 0.05) lower temperature than the other Colorado potato beetle populations. The temperature at which Virginia Colorado potato beetle supercooled is indicative of freeze-sensitive species and may indicate divergence in the mechanisms Colorado potato beetle are using for cold tolerance. Two polyhydric alcohols (polyols) were isolated in the hemolymph of Colorado potato beetle using high performance thin layer chromatography. The polyols were tentatively identified as inositol and xylitol. / Ph. D.

Proterozoic rocks in the Needle Mountains include ca. 1750 Ma amphibolite-grade, metavolcanic and metaplutonic gneisses and ca. 1690 Ma granitoids that comprise the basement to the siliciclastic Uncompahgre Group. The mafic and felsic gneisses underwent synkinematic metamorphism and two phases of isoclinal folding and foliation development during D_B, prior to emplacement of the ca. 1690 Ma plutons. D_BC deformation caused folding of D_B fabrics in the gneisses, development of a subvertical, east-striking foliation in the granitoids, and generation of a macroscopic sigmoidal foliation pattern throughout the area prior to 1430 Ma. D_BC structures in the basement are correlated with macroscopic structures in the Uncompahgre Group, which was deformed into an east-trending cuspate synclinorium during this event. Gently plunging mineral lineations and asymmetric kinematic indicators in the basement record a component of dextral strike-slip shearing in domains of east-striking foliation and sinistral shearing in areas of northeast-striking foliation. A model for D_BC involving the development of conjugate strike-slip shear zones in response to north-northwest shortening is most consistent with the kinematic and fabric orientation data. A zone of phyllite, derived largely from basement, occurs everywhere along the basement-cover contact. Kinematic indicators along and near the contact record upward movement of the cover relative to the basement on each side of the synclinorium and imply that the cover rocks are parautochthonous. Stratigraphic facing of the cover rocks away from the basement supports the interpretation of this contact as an unconformity at the base of the Uncompahgre Group. Alteration of the basement rocks along this contact involved hydration and the loss of CaO, MgO, SiO₂, and Na₂O. The phyllite zone is interpreted as a metamorphosed and deformed regolith that localized out-of-synform movement while the basement and its parautochthonous cover were folded together during D_BC. Rocks in the Needle Mountains comprise part of the Colorado Province, one of several terranes that were possibly accreted to the Archean Wyoming Craton during the Proterozoic. Age constraints on the timing of deformation indicate that D_B and D_BC are representative of two regionally extensive deformational episodes. Pre-1700 Ma deformation is attributed to the assembly of volcanogenic terranes and their accretion to the Wyoming Craton along the Cheyenne Belt. Post-1700 Ma deformation resulted from regional north-northwest crustal shortening induced by tectonic interactions along the southern margin of the Colorado Province. These results support the hypothesis that terrane accretion was important in the Proterozoic crustal evolution of southwestern North America. / Ph. D.

No description available.

Project report (D.Min.)--Golden Gate Baptist Theological Seminary, 2008. / Typescript. Description based on Print version record. Includes bibliographical references (leaves 101-103).

No description available.