Epithermal vein and carbonate replacement mineralization related to caldera development, Cunningham Gulch, Silverton, Colorado

textEpithermal vein and carbonate replacement deposits in Cunningham Gulch are located within the western San Juan Tertiary volcanic field in southwestern Colorado. The Pride of the West epithermal vein system is hosted within the intracaldera facies of the Sapinero Mesa Tuff, a voluminous ash-flow tuff that erupted from and resulted in the formation of the San Juan Caldera at 28 mybp. The Pride of the West vein system is developed along a radial fracture formed during resurgence of the San Juan Caldera prior to eruption of the Crystal Lake Tuff (27.5 mybp). This eruption led to the concomitant collapse of the Silverton Caldera, nested within the larger San Juan Caldera. The Pride of the West, Osceola, and Little Fanny mines are positioned near the intersection of the Pride radial fracture system and the buried structural margin of the San Juan Caldera, suggesting that ore concentration was controlled by this structural setting. Large limestone blocks of the Mississippian Leadville Formation are incorporated into the intracaldera fill volcanics in the mine area. These blocks appear to have been engulfed within mudflow breccias of the Tertiary San Juan Formation (32.1 mybp). They were then emplaced in their present structural position within a caldera-collapse breccia which caved from the oversteepened margin of the San Juan Caldera. Regional propylitic alteration of the hosting volcanics to a chlorite-calcite-pyrite assemblage preceded vein-associated alteration and mineralization. The veins are enveloped by a narrow phyllic alteration assemblage of quartz, sericite, illite, kaolinite, and pyrite. The veins are comprised of sphalerite, galena, chalcopyrite, pyrite, hematite, magnetite, quartz, pyroxmangite, calcite, and minor barite. Substantial bodies of replacement ore are present where the vein structures intersect the limestone blocks; the mineral assemblages of the replacement deposits are identical to those of the feeding vein structures. Commonly, replacement textures are spectacular concentrations, especially the "zebra ore" which primarily consists of regularly spaced, alternating bands of sulfides and quartz. These "zebra" laminations are stratigraphically controlled and appear to represent replacement of a depositional or diagenetic fabric. Main ore-stage mineralization began with widespread deposition of quartz with or without pyrite, followed by sphalerite, chalcopyrite, and galena. Post ore-stage brecciation and silicification events are evident and were followed by deposition of calcite and minor barite during the waning stages of the hydrothermal system. The distributions of Fe, Mn, Pb, and Ca suggest a lateral component of fluid flow from northwest the southeast, away from the structural margin of the Silverton Caldera. Fluid inclusion data from both vein and replacement-type sphalerite and quartz indicate that mineral deposition occurred over a range of 200 to 312°C (mean 243°C) from solutions containing 1 to 5% total salts. The high base metal to precious metal content of the ore, the phyllic alteration assemblage, and the temperature and composition of the ore-forming fluid indicate that the mine workings are within the lower portion of a fossil geothermal system.Geological Science

Influence of urbanization on living away type of marriage: the case of Kampala City (Uganda)

Living away type of marriage was found to be on an upward trend and more common in urban (36.1%) than rural areas (19.2%). Logistic regression analysis showed that urban residents were 2 times more likely to be in living away type of marriage than their rural counterparts. Area of residence was the most significant factor in influencing living away type of marriage. The study revealed that living away type of marriage was due to some married men being migrant workers leaving their wives at home to maintain their family investments and the nature of jobs that make separation of spouses inevitable. The problem of accommodation in urban areas due to shortage of houses was evident from being responsible for 17% of urban residents in living away type of marriage. Living away type of marriage was implicated as being one of the causes of the spread of HIV/AIDs. Separation of couples predisposes these groups to have sexual contacts with multiple partners. Married spouses that stayed together were at lower risk of being HIV seropositive than those staying apart (UNFPA, 2006)

The Arecibo Observatory as an Instrument for Investigating Orbital Debris: Legacy and Next Generation Performance

In this paper, we investigate the ability of the Arecibo Observatory to characterize the orbital debris environment and compare it to the primary instrument used by NASA\u27s Orbital Debris Program Office, the Haystack Ultra-Wideband Satellite Imaging Radar (HUSIR). Arecibo\u27s location (183 N) increases the percentage of observable orbits (relative to HUSIR) by 27%, which gives Arecibo access to a much larger and previously unmeasured portion of the environment. Due to the recent collapse of the Arecibo dish, in addition to exploring historic capabilities of the Legacy Arecibo Telescope, estimates of the performance of the proposed Next Generation Arecibo Telescope (NGAT) are explored. We show that the current NGAT design could have a sensitivity comparable to the Goldstone Orbital Debris Radar, currently NASA\u27s most sensitive orbital debris radar. Additionally, design suggestions are presented that would significantly improve the capabilities of the NGAT for orbital debris investigations. We show that, with appropriate hardware upgrades, it would be possible to achieve a minimum-detectable debris size as small as 1 mm. These capabilities would allow data from Arecibo to significantly improve short-term debris environment models, which are used to inform spacecraft design and operations, particularly for orbital debris smaller than 3 mm, which pose the highest penetration risk to most spacecraft

A method for calculating lateral surface area of bistatic radar beam overlap

It has been shown that bistatic radars using radio telescopes as receivers can be used to increase the sensitivity of orbital debris measurements over traditional terrestrial monostatic radar. A method to calculate the lateral surface area of a bistatic radar is needed to evaluate the efficacy of a proposed bistatic radar configuration for orbital debris measurements. For over three decades, models of the orbital debris (OD) environment in low Earth orbit (LEO) have been developed to assess the risk posed by OD to spacecraft. While terrestrial radar measures debris 3 mm and larger and in situ measurements provide data for debris smaller than 1 mm, no good data sources exist for debris between 1 mm and 3 mm in size. This results in large variations between competing OD models. It also happens to be the size regime which poses the highest mission-ending risk to spacecraft. It is, therefore, of interest to investigate potential new data sources for this under-sampled size regime. There are many radars and radio telescopes that could be combined to create sensitive bistatic radars that could potentially bridge the size gap. In addition to sensitivity, it is necessary to predict the expected count rate of a candidate sensor to evaluate its performance. NASA’s Orbital Debris Engineering Model (ORDEM) can be used to predict the flux of debris passing through the line of sight of a radar or telescope. This flux is related to a count rate through the calculation of the lateral surface area of the sensor. While this can be done easily for monostatic radars, a method for calculating the lateral surface area of a bistatic radar is needed. This new method of calculation has been developed and is described. The new method maps the radar beam overlap in 3D space, calculating the area of the complex surface formed by the gain product of the two antennas. Comparisons of the monostatic and new bistatic lateral surface area calculation methods for the monostatic case are presented. Results of a sample lateral surface area calculation for a bistatic radar observation configuration currently employed by NASA are shown. Finally, a guide for total error as a function of baseline and target altitude is established

Contribution of Microfinance Credit on Poverty Reduction among the Agricultural Rural Women in Keiyo North District, Elgeyo-Marakwet County, Kenya

Microfinance institutions provide small loans to rural women to improve their living standards. The main purpose of microfinance credit programme is to break the vicious cycle of poverty among the rural women by providing them with capital. Poverty is a global problem; more than 1.3 billion people worldwide live below the poverty line, 70% of them being women. In Keiyo North district, 48% of the population lives below the poverty line with women constituting 65% of those living below the poverty line. However, less rural women in Keiyo North district participate in the microfinance credit programme despite the fact that Kenya Women Finance Trust (KWFT) operates in all the 13 sub-locations in the district. This study sought to investigate the contribution of microfinance credit on poverty reduction among the rural women in Keiyo North district. The study used a descriptive survey design to collect data. The target population was 220 of the rural women participating in groups in microfinance credit programme from which a sample of 130 rural women was drawn. An open and close-ended questionnaire was used. A pilot study was conducted among the 30 KWFT rural women participants and a Cronbach’s Apha coefficient reliability of 0.71 was attained. The validity of the instrument was ascertained by experts from Agricultural Education and Extension in the Faculty of Education and Community studies and supervisors of Egerton University. Data was analyzed using chi-square α=0.05 significance level. Results indicated that microfinance credit programme has improved household level of income and acquisition of assets among the rural women in Keiyo North district. In addition, the rural women can also afford health care services for their families as a result of participating in microfinance credit programme. The study recommends that microfinance institutions (MFIs) should encourage more rural women to participate in microfinance credit programme to increase their levels of income and raise their household assets ownership. The county government should sensitize more rural women on the need to join the microfinance credit programme in order to boost their ability to afford health care services for their families. Keywords: Microfinance credit, poverty, Income, Asset acquisition, Health care, Agricultural rural women

An investigation of the volatile organic compounds produced during fermentation

Call number: LD2668 .T4 1958 L42Master of Scienc

Development of a temperature-pneumatic probe and application at the rotor exit in a transonic compressor

The development is reported of a new combination temperature-pneumatic probe specifically to determine the blade element performance of the rotor in a transonic compressor. The design incorporates a fine wire thermocouple sensor which provides a measure of temperature rise that is insensitive to Mach number. With simultaneous measurements from four pneumatic sensors, the velocity vector was determined locally is radial surveys downstream of the compressor rotor. The probe was calibrated in a free jet. The calibration measurements were reduced to a set of equations to allow off-line reduction of compressor measurements using a Hewlett-Packard Model 9830A calculator and peripherals. The design, development, calibration, and application of the probe are described and initial results of measurements in the compressor are given.http://archive.org/details/developmentoftem00dodgLieutenant, United States NavyApproved for public release; distribution is unlimited

Conceptual design of a manned orbital transfer vehicle

With the advent of the manned space station, man now requires a spacecraft based on the space station with the ability to deploy, recover, and repair satellites quickly and economically. Such a craft would prolong and enhance the life and performance of many satellites. A basic design was developed for an orbital tansfer vehicle (OTV). The basic design criteria are discussed. The design of the OTV and systems were researched in the following areas: avionics, crew systems, electrical power systems, environmental control/life support systems, navigation and orbital maneuvers, propulsion systems, reaction control systems (RCS), servicing systems, and structures. The basic concepts in each of the areas are summarized