Map showing reconnaissance geochemistry in the gold-pyrophyllite belt of northwestern Moore County, North Carolina

USGS Publications Warehouse

Lesure, Frank G.

1981-01-01

Traces of gold and molybdenum are widely disseminated in an area approximately 35 km long and 10 km wide in northwestern Moore County, N.C.  At least 2540 oz. of gold were recovered from 16 or more mines and prospects between 1880 and 1910.  One hundred and ninety rock samples out of 244 collected from old gold mines, pyrophyllite deposits and along roads contain gold quantities ranging from 0.02 to 2.4 parts per million.  In addition, 43 samples out of the 244 taken contain molybdenum in amounts ranging from 4 to 500 parts per million.

Stabilization of lead in an alkali-activated municipal solid waste incineration fly ash-Pyrophyllite-based system.

PubMed

Shiota, Kenji; Nakamura, Takafumi; Takaoka, Masaki; Aminuddin, Siti Fatimah; Oshita, Kazuyuki; Fujimori, Takashi

2017-10-01

This work focuses on the stabilization and speciation of lead (Pb) in a composite solid produced from an alkali-activated municipal solid waste incineration fly ash (MSWIFA)-pyophyllite-based system. The solid product was synthesized after mixtures of raw materials (dehydrated pyrophyllite, MSWIFA, 14 mol/L aqueous sodium hydroxide, and sodium silicate solution) were cured at 105 °C for 24 h. The product could reduce the leaching of Pb and the Pb concentration in the leachate was 7.0 × 10 -3 using the Japanese leaching test and 9.7 × 10 -4  mg/L using toxicity characteristics leaching procedure method, which satisfied the respective test criteria and successfully stabilized Pb in this system. The solid product had a compressive strength of 2 MPa and consisted mainly of crystalline phases. Scanning electron microscopy with X-ray analysis and X-ray absorption fine structure suggested that Pb was present along with Al, Si, and O, and that the atomic environment around the Pb was similar to that of PbSiO 3 . These results suggest that the alkali-activated MSWIFA-pyrophyllite-based system could be used to stabilize Pb in MSWIFA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical kinetics of Cs species in an alkali-activated municipal solid waste incineration fly ash and pyrophyllite-based system using Cs K-edge in situ X-ray absorption fine structure analysis

NASA Astrophysics Data System (ADS)

Shiota, Kenji; Nakamura, Takafumi; Takaoka, Masaki; Nitta, Kiyofumi; Oshita, Kazuyuki; Fujimori, Takashi; Ina, Toshiaki

2017-05-01

We conducted in situ X-ray absorption fine structure (in situ XAFS) analysis at the Cs K-edge to investigate the chemical kinetics of Cs species during reaction in an alkali-activated municipal solid waste incineration fly ash (MSWIFA) and pyrophyllite-based system. Understanding the kinetics of Cs is essential to the design of appropriate conditions for Cs stabilization. In situ XAFS analysis of four pastes, prepared from NaOHaq, sodium silicate solution, pyrophyllite, and MSWIFA with the addition of CsCl, was conducted in custom-built reaction cells at four curing temperatures (room temperature, 60 °C, 80 °C, 105 °C) for approximately 34 h. The results indicated that the change in Cs species during reaction at room temperature was small, while changes at higher temperatures were faster and more extreme, with the fastest conversion to pollucite occurring at 105 °C. Further analysis using a leaching test and a simple reaction model for Cs species during reaction showed that the pollucite formation rate was dependent on the curing temperature and had a significant negative correlation with Cs leaching. The activation energy of pollucite formation was estimated to be 31.5 kJ/mol. These results revealed that an important change in the chemical state of Cs occurs during reaction in the system.

Fe(II) sorption on pyrophyllite: Effect of structural Fe(III) (impurity) in pyrophyllite on nature of layered double hydroxide (LDH) secondary mineral formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starcher, Autumn N.; Li, Wei; Kukkadapu, Ravi K.

Fe(II)-Al(III)-LDH (layered double hydroxide) phases have been shown to form from reactions of aqueous Fe(II) with Fe-free Al-bearing minerals (phyllosilicate/clays and Al-oxides). To our knowledge, the effect of small amounts of structural Fe(III) impurities in “neutral” clays on such reactions, however, were not studied. In this study to understand the role of structural Fe(III) impurity in clays, laboratory batch studies with pyrophyllite (10 g/L), an Al-bearing phyllosilicate, containing small amounts of structural Fe(III) impurities and 0.8 mM and 3 mM Fe(II) (both natural and enriched in 57Fe) were carried out at pH 7.5 under anaerobic conditions (4% H2 – 96%more » N2 atmosphere). Samples were taken up to 4 weeks for analysis by Fe-X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy. In addition to the precipitation of Fe(II)-Al(III)-LDH phases as observed in earlier studies with pure minerals (no Fe(III) impurities in the minerals), the analyses indicated formation of small amounts of Fe(III) containing solid(s), most probably hybrid a Fe(II)-Al(III)/Fe(III)-LDH phase. The mechanism of Fe(II) oxidation was not apparent but most likely was due to interfacial electron transfer from the sorbed Fe(II) to the structural Fe(III) and/or surface-sorption-induced electron-transfer from the sorbed Fe(II) to the clay lattice. Increase in the Fe(II)/Al ratio of the LDH with reaction time further indicated the complex nature of the samples. This research provides evidence for the formation of both Fe(II)-Al(III)-LDH and Fe(II)-Fe(III)/Al(III)-LDH-like phases during reactions of Fe(II) in systems that mimic the natural environments. Better understanding Fe phase formation in complex laboratory studies will improve models of natural redox systems.« less

Comprehensive Study on Ceramic Membranes for Low‐Cost Microbial Fuel Cells

PubMed Central

Pasternak, Grzegorz; Greenman, John

2016-01-01

Abstract Microbial fuel cells (MFCs) made with different types of ceramic membranes were investigated to find a low‐cost alternative to commercially available proton exchange membranes. The MFCs operated with fresh human urine as the fuel. Pyrophyllite and earthenware produced the best performance to reach power densities of 6.93 and 6.85 W m−3, respectively, whereas mullite and alumina achieved power densities of 4.98 and 2.60 W m−3, respectively. The results indicate the dependence of bio‐film growth and activity on the type of ceramic membrane applied. The most favourable conditions were created in earthenware MFCs. The performance of the ceramic membranes was related to their physical and chemical properties determined by environmental scanning electron microscopy and energy dispersive X‐ray spectroscopy. The cost of mullite, earthenware, pyrophyllite and alumina was estimated to be 13.61, 4.14, 387.96 and 177.03 GBP m−2, respectively. The results indicate that earthenware and mullite are good substitutes for commercially available proton exchange membranes, which makes the MFC technology accessible in developing countries. PMID:26692569

Hydrogen and oxygen isotope exchange reactions between clay minerals and water

USGS Publications Warehouse

O'Neil, J.R.; Kharaka, Y.K.

1976-01-01

The extent of hydrogen and oxygen isotope exchange between clay minerals and water has been measured in the temperature range 100-350?? for bomb runs of up to almost 2 years. Hydrogen isotope exchange between water and the clays was demonstrable at 100??. Exchange rates were 3-5 times greater for montmorillonite than for kaolinite or illite and this is attributed to the presence of interlayer water in the montmorillonite structure. Negligible oxygen isotope exchange occurred at these low temperatures. The great disparity in D and O18 exchange rates observed in every experiment demonstrates that hydrogen isotope exchange occurred by a mechanism of proton exchange independent of the slower process of O18 exchange. At 350?? kaolinite reacted to form pyrophyllite and diaspore. This was accompanied by essentially complete D exchange but minor O18 exchange and implies that intact structural units in the pyrophyllite were inherited from the kaolinite precursor. ?? 1976.

Comprehensive Study on Ceramic Membranes for Low-Cost Microbial Fuel Cells.

PubMed

Pasternak, Grzegorz; Greenman, John; Ieropoulos, Ioannis

2016-01-08

Microbial fuel cells (MFCs) made with different types of ceramic membranes were investigated to find a low-cost alternative to commercially available proton exchange membranes. The MFCs operated with fresh human urine as the fuel. Pyrophyllite and earthenware produced the best performance to reach power densities of 6.93 and 6.85 W m(-3), respectively, whereas mullite and alumina achieved power densities of 4.98 and 2.60 W m(-3), respectively. The results indicate the dependence of bio-film growth and activity on the type of ceramic membrane applied. The most favourable conditions were created in earthenware MFCs. The performance of the ceramic membranes was related to their physical and chemical properties determined by environmental scanning electron microscopy and energy dispersive X-ray spectroscopy. The cost of mullite, earthenware, pyrophyllite and alumina was estimated to be 13.61, 4.14, 387.96 and 177.03 GBP m(-2), respectively. The results indicate that earthenware and mullite are good substitutes for commercially available proton exchange membranes, which makes the MFC technology accessible in developing countries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

NASA Astrophysics Data System (ADS)

Lackschewitz, K. S.; Devey, C. W.; Stoffers, P.; Botz, R.; Eisenhauer, A.; Kummetz, M.; Schmidt, M.; Singer, A.

2004-11-01

During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ˜250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ˜300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly present in the pyrophyllites. Illite shows a significant enrichment for Cs and Cu relative to the bulk altered samples. Considerations of mineral stability allow us to place some constraints on fluid chemistry. Hydrothermal fluid pH for the chloritization and illitization was neutral to slightly acidic and relatively acidic for the pyrophyllite alteration. In general the fluids, especially from Roman Ruins and at intermediate depths below Snowcap, show only a small proportion of seawater mixing (<10%). Fluids in shallow and deep parts of the Snowcap holes, in contrast, show stronger seawater influence.

Stabilization of cesium in alkali-activated municipal solid waste incineration fly ash and a pyrophyllite-based system.

PubMed

Shiota, Kenji; Nakamura, Takafumi; Takaoka, Masaki; Aminuddin, Siti Fatimah; Oshita, Kazuyuki; Fujimori, Takashi

2017-11-01

Environmentally sound treatments are required to dispose of municipal solid waste incineration fly ash (MSWIFA) contaminated with radioactive cesium (Cs) from the Fukushima Daiichi nuclear power plant accident in Japan. This study focuses on the stabilization of Cs using an alkali-activated MSWIFA and pyophyllite-based system. Three composite solid products were synthesized after mixtures of raw materials (dehydrated pyrophyllite, MSWIFA, 14 mol/L aqueous sodium hydroxide, and sodium silicate solution) were cured at 105 °C for 24 h. Three types of MSWIFAs were prepared as raw fly ash, raw fly ash with 0.1% CsCl, and raw fly ash with 40% CsCl to understand the stabilization mechanism of Cs. Cs stabilization in two solid products was successful, with less than 6.9% leaching observed from two types tests, and was partly successful for the solid product with the highest concentration of Cs. X-ray diffraction showed that all of the solid products produced several crystalline phases, and that pollucite was formed in the highest Cs concentration product. The X-ray absorption fine structure and scanning electron microscopy with X-ray analysis suggested that most Cs species formed pollucite in the two solid products from MSWIFA with added CsCl. This system provides a technique for the direct stabilization of Cs in MSWIFA. Copyright © 2017 Elsevier Ltd. All rights reserved.

New Measurements of Activation Volume in Olvine Under Anhydrous Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durham, W.; Mei, S; Kohlstedt, D

2009-01-01

A new cell assembly for the deformation-DIA (D-DIA) shows promise for limiting the water content of samples and providing a more mechanically stable environment for deformation. The 6-mm cubic cell consists of a 6-mm diameter mullite sphere cradled in a web of unfired pyrophyllite. The pyrophyllite flows during initial compression of the D-DIA to form gaskets between the six anvils while the mullite flows to become a nearly cubic-shaped pressure medium. Measurements on olivine indicate more than one order of magnitude drop in water content to <40 ppm H/Si compared with the boron-epoxy medium. Improved mechanical stability is achieved bymore » elimination of the thermocouple from the assembly and determination of temperature from calibration curves of furnace power vs. temperature. Three samples of polycrystalline orthopyroxene-buffer San Carlos olivine have been deformed in high-temperature creep in the new cell, at pressures of 2.7-4.9 GPa and temperatures near 1473 K. Strength is consistent with that measured in the gas-apparatus at lower pressures. Over the pressure range investigated we resolve an activation volume for creep of dry olivine of V* = 9.5 {+-} 7 x 10-6 m3/mol.« less

Mineralogy of a perudic Andosol in central Java, Indonesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Ranst, Eric; Utami, S. R.; Verdoodt, A.

2008-02-15

We studied the mineralogy of a perudic Andosol developed on the Dieng Tephra Sequence in central Java, Indonesia. The objective was to confirm the presence and determine the origin and stability of 2:1 and interlayered 2:1 phyllosilicates in well-drained Andosols. This was and still is a debated topic in the literature. Total elemental and selective dissolution, as well as microscopic and X-ray diffraction analyses, were performed on the soil samples collected from this site. These analyses confirmed that andic properties were present in the soil samples. The allophane content determined by selective dissolution was 3-4% in the A horizons, andmore » increased to 12-18% in the deeper subsoil horizons. In addition, the clay fraction contained dioctahedral smectite, hydroxy-Al-interlayered 2:1 minerals (HIS), Al-chlorite, kaolinite, pyrophyllite, mica, cristobalite and some gibbsite. The silt and sand fractions were rich in plagioclase and pyroxene. The 2:1 minerals (smectite and pyrophyllite), as well as chlorite and kaolinite were of hydrothermal origin and were incorporated in the tephra during volcanic eruption. Besides desilication during dissolution of unstable minerals, Al interlayering of 2:1 layer silicates was most likely the most prominent pedogenic process. Although hydroxy-Al polymeric interlayers would normally stabilize the 2:1 clay phases, the strong weakening, and even disappearance of the characteristic XRD peaks, indicated instability of these minerals in the upper A horizons due to the perudic and intensive leaching conditions.« less

Fundamental investigation of the tribological and mechanical responses of materials and nanostructures

NASA Astrophysics Data System (ADS)

Bucholz, Eric W.

In the field of tribology, the ability to predict, and ultimately control, frictional performance is of critical importance for the optimization of tribological systems. As such, understanding the specific mechanisms involved in the lubrication processes for different materials is a fundamental step in tribological system design. In this work, a combination of computational and experimental methods that include classical molecular dynamics (MD) simulations, atomic force microscopy (AFM) experiments, and multivariate statistical analyses provides fundamental insight into the tribological and mechanical properties of carbon-based and inorganic nanostructures, lamellar materials, and inorganic ceramic compounds. One class of materials of modern interest for tribological applications is nanoparticles, which can be employed either as solid lubricating films or as lubricant additives. In experimental systems, however, it is often challenging to attain the in situ observation of tribological interfaces necessary to identify the atomic-level mechanisms involved during lubrication and response to mechanical deformation. Here, classical MD simulations establish the mechanisms occurring during the friction and compression of several types of nanoparticles including carbon nano-onions, amorphous carbon nanoparticles, and inorganic fullerene-like MoS2 nanoparticles. Specifically, the effect of a nanoparticle's structural properties on the lubrication mechanisms of rolling, sliding, and lamellar exfoliation is indicated; the findings quantify the relative impact of each mechanism on the tribological and mechanical properties of these nanoparticles. Beyond identifying the lubrication mechanisms of known lubricating materials, the continual advancement of modern technology necessitates the identification of new candidate materials for use in tribological applications. To this effect, atomic-scale AFM friction experiments on the aluminosilicate mineral pyrophyllite demonstrate that pyrophyllite provides a low friction coefficient and low shear stresses as well as a high threshold to interfacial wear; this suggests the potential for use of pyrophyllite as a lubricious material under specific conditions. Also, a robust and accurate model for estimating the friction coefficients of inorganic ceramic materials that is based on the fundamental relationships between material properties is presented, which was developed using multivariate data mining algorithms. These findings provide the tribological community with a new means of quickly identifying candidate materials that may provide specific frictional properties for desired applications.

Formation of organoclays by a one step synthesis

NASA Astrophysics Data System (ADS)

Jaber, Maguy; Miéhé-Brendlé, Jocelyne; Delmotte, Luc; Le Dred, Ronan

2005-05-01

Different lamellar hybrid inorganic-organic materials having as inorganic parent 2:1 (T.O.T.) phyllosilicates such as talc, saponite, pyrophyllite, beidellite and montmorillonite were prepared by a one step synthesis. The solids were characterized by X-ray diffraction, solid state 29Si, 27Al, and 19F nuclear magnetic resonance and transmission electron microscopy. XRD patterns show that solids with inorganic parents having octahedral sheet based on aluminium exhibit a lamellar structure similar to MCM-50, whereas those with magnesium have an organophyllosilicate structure. In the first case, the absence of hexacoordinated aluminium was confirmed by 27Al NMR and an ordered stacking of the layers is observed on TEM micrographs. In opposite, a disorder is observed on the TEM images of organophyllosilicates. The formation of the 2:1 structure was found to be controlled mainly by the insertion of silicic species in the interlamellar space of brucite like layers.

Geology and Mineral Deposits of the Snow Camp-Saxapahaw Area, Central North Carolina

USGS Publications Warehouse

Schmidt, Robert G.; Gumiel, Pablo; Payas, Alba

2006-01-01

The Snow Camp-Saxapahaw study area, in the Carolina slate belt in the Southeastern United States, is notable for large zones of high-sulfidation alteration in arc-related metavolcanic rocks. The area has potential for additional significant pyrophyllite and related aluminosilicate refractory mineral deposits and may have potential for small- to medium-size gold deposits also associated with the high-sulfidation hydrothermal systems. The Carolina slate belt is an elongate zone of mostly low-grade metamorphic rocks of Neoproterozoic to early Paleozoic age that extends from northeastern Georgia to southern Virginia. It is dominated by volcanic rocks but locally consists of fine-grained epiclastic sedimentary rocks. Plutons and subvolcanic bodies have intruded the rocks of the Carolina slate belt in many places and have been important in controlling the metamorphism and in localizing hydrothermal alteration. The Snow Camp-Saxapahaw area is mostly underlain by volcanic and volcaniclastic rocks and lesser amounts of intrusive shallow plutons. The volcanic rocks range in composition from basalt to rhyolite; however andesites, dacites, and rhyodacites are the most abundant. The intrusive bodies are largely granite and quartz monzonite; gabbroic bodies also are common. It was possible to establish the relative ages of only part of these rocks. Two northeast-trending fault zones and fractures divide the map area into three structural blocks; the central block was tilted down to the southwest to form a grabenlike structure. Most of the hydrothermally altered rocks and all of the intensely altered zones are confined to the downdropped block, which we think may have been calderalike in origin. A major volcanic unit, the Reedy Branch Tuff, is limited to the southwestern part of the graben and may be the youngest volcanic rock in the area. Layered rocks record one or more strong folding events, but the diversity of rock types, lack of recognizable stratigraphic markers, and uneven distribution of outcrops prevented comprehensive structural studies. Except for a few late plutons and dikes, all of the rocks of the area have been metamorphosed in middle to upper greenschist facies, and contact aureoles were recognized around some of the plutons. Several relatively small bodies of granitic rock contain plagioclase grains in which primary oscillatory zoning was unaffected by metamorphism. These were interpreted to be post-metamorphic. We think that there were three separate stages of hydrothermal alteration in the complex volcanic terrane in the area. The oldest, an area of at least 8.5 square miles (22 square kilometers), was subjected to an intense hydrothermal alteration, ranging from peripheral zones of quartz-sericite-paragonite through a patchy marginal zone of pyrophyllite, andalusite, and other high-alumina minerals, to almost totally silicified core zones. The second event resulted in large areas of weak to moderate sericitic and propylitic alteration recognizable only in the Reedy Branch Tuff. The last event was related to post-metamorphic plutons. All of the pyrophyllite-andalusite deposits and perhaps most of the gold and silver mineralization can be related to the first period of hydrothermal alteration. The subsequent metamorphism did not produce significant changes in mineral species in the zones of most intense hydrothermal alteration. Gold- and silver-bearing sulfide minerals in fracture zones along the southeastern margin of the graben may also have been deposited during this earliest alteration stage. No metallic mineralization appears to have occurred during the second event. A group of molybdenum-bearing greisenlike bodies formed during the emplacement of the youngest plutons during the post-metamorphic event. One gold-bearing sulfide zone occurs in the exocontact of one such porphyritic stock. Significant amounts of pyrophyllite-andalusite-bearing rock have been extracted from the Snow Camp Mine and from

Investigation of Cyclodextrin-Enhanced Electrokinetic Soil Remediation. Fate and Transport of Nitroaromatic Contaminants and Cyclodextrin Amendments in Expansive Clays

DTIC Science & Technology

2004-09-01

report increasing adsorption capacity depending on the specific clay type, in the order kaolinite < illite < montmorillonite (11). This finding suggests... kaolinite , illite, and montmorillonite . Finally, there is a wide varia- tion in adsorption constants among the different nitroaromatic compounds...common to micas, chlorites, pyrophyllite, talc, kaolinite , and gibbsite . As is now known, clays typically consist of layered crystalline structures

Inorganic Water Repellent Coatings for Thermal Protection Insulation on an Aerospace Vehicle

NASA Technical Reports Server (NTRS)

Fuerstenau, D. W.; Huang, P.; Ravikumar, R.

1997-01-01

The objective of this research was two-fold: first, to identify and test inorganic water-repellent materials that would be hydrophobic even after thermal cycling to temperatures above 600 C and, second, to develop a model that would link hydrophobicity of a material to the chemical properties of its constituent atoms. Four different materials were selected for detailed experimental study, namely, boron nitride, talc, molybdenite, and pyrophyllite, all of which have a layered structure made up of ionic/covalent bonds within the layers but with van der Waals bonds between the layers. The materials tested could be considered hydrophobic for a nonporous surface but none of the observed contact angles exceeded the necessary 90 degrees required for water repellency of porous materials. Boron nitride and talc were observed to retain their water-repellency when heated in air to temperatures that did not exceed 800 C, and molybdenite was found to be retain its hydrophobicity when heated to temperatures up to 600 C. For these three materials, oxidation and decomposition were identified to be the main cause for the breakdown of water repellency after repeated thermal cycling. Pyrophyllite shows the maximum promise as a potential water-repellent inorganic material, which, when treated initially at 900 C, retained its shape and remained hydrophobic for two thermal cycles where the maximum retreatment temperature is 900 C. A model was developed for predicting materials that might exhibit hydrophobicity by linking two chemical properties, namely, that the constituent ions of the compound belong to the soft acid-base category and that the fractional ionic character of the bonds be less than about 20 percent.

Velocity distribution of fragments of catastrophic impacts

NASA Technical Reports Server (NTRS)

Takagi, Yasuhiko; Kato, Manabu; Mizutani, Hitoshi

1992-01-01

Three dimensional velocities of fragments produced by laboratory impact experiments were measured for basalts and pyrophyllites. The velocity distribution of fragments obtained shows that the velocity range of the major fragments is rather narrow, at most within a factor of 3 and that no clear dependence of velocity on the fragment mass is observed. The NonDimensional Impact Stress (NDIS) defined by Mizutani et al. (1990) is found to be an appropriate scaling parameter to describe the overall fragment velocity as well as the antipodal velocity.

Impacts of Pantoea agglomerans strain and cation-modified clay minerals on the adsorption and biodegradation of phenanthrene.

PubMed

Tao, Kelin; Zhao, Song; Gao, Pin; Wang, Lijin; Jia, Hanzhong

2018-06-06

Interactions between microorganisms and minerals have the potential contribution to remove polycyclic aromatic hydrocarbons (PAHs) in model systems. In this study, phenanthrene (PHE) was used as a probe molecule to explore the potential adsorption and biotransformation processes in the presence of microorganisms and various reference clays, such as montmorillonite (M), kaolinite (K), and pyrophyllite (P). Equilibrium adsorption experiments and scanning electron microscopy (SEM) technique were used to investigate the sorption of Pantoea agglomerans strains on clay minerals saturated with cations (Na + and Fe 3+ ). The adsorption isotherms of PHE and Pantoea agglomerans strains on cation-modified clay minerals fitted to Langmuir equation, and their adsorbed amounts both followed the sequence: montmorillonite > kaolinite > pyrophyllite. For six types of cation-modified minerals, the behavior of PHE adsorbed and Pantoea agglomerans adhered onto mentioned minerals was in the order of Na(I)-M > Fe(Ⅲ)-M, Na(I)-K > Fe(Ⅲ)-K and Fe(Ⅲ)-P > Na(I)-P, respectively. The biodegradation results showed that cation-modified clay minerals could enhance the biodegradation of PHE, ascribing to their large specific surface area, and cation exchange capability, as well as the difference in zeta potential between minerals and Pantoea agglomerans strains. Comparison of biodegradation rates displayed that PHE was degraded the highest in the presence of Na-M (93.285%). In addition, the obtained results suggested that the adhesion of bacteria onto cation-exchanged clay minerals was beneficial to the biodegradation of PHE. Anthracen-9-ylmethanol and 3,4-dimethyl-2-(3-methylbutanoyl)benzoic acid were detected as the main intermediate compounds, which can be further biodegraded into small molecules. The overall results obtained in this study are of valuable significance for the understanding of the behavior of PHE in soil and associated environment. Copyright © 2018 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starcher, Autumn N.; Elzinga, Evert J.; Sparks, Donald L.

Previous research demonstrated the formation of single divalent metal (Co, Ni, and ZnAl) and mixed divalent metal (NiZnAl) layered double hydroxide (LDH) phases from reactions of the divalent metal with Al-bearing substrates and soils in both laboratory experiments and in the natural environment. Recently Fe(II)-Al-LDH phases have been found in laboratory batch reaction studies, and although they have yet to be found in the natural environment. Potential locations of Fe(II)-Al-LDH phases in nature include areas with suboxic and anoxic conditions. Because these areas can be environments of significant contaminant accumulation, it is important to understand the possible interactions and impactsmore » of contaminant elements on LDH phase formation. One such contaminant, Zn, can also form as an LDH and has been found to form as a mixed divalent layered hydroxide phase. To understand how Zn impacts the formation of Fe(II)-Al-LDH phase formation and kinetics, 3 mM or 0.8 mM Fe(II) and 0.8 mM Zn were batch reacted with either 10 g/L pyrophyllite or 7.5 g/L γ-Al2O3 for up to three months under anoxic conditions. Aqueous samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) and solid samples were analyzed with X-ray absorption spectroscopy (XAS). Shell-by-shell fits of Fe(II) and co-sorption samples with pyrophyllite show the formation of a mixed divalent metal (Fe(II)-Zn-Al) layered hydroxide phase, while Fe(II) and Zn co-sorption samples with γ-Al2O3 produce Fe(II)-Al-LDH phases and Zn in inner-sphere complexation with the γ-Al2O3. This study demonstrates the formation of a mixed divalent metal layered hydroxide and further iterates the importance of sorbent reactivity on LDH phase formation.« less

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Svoboda, Martin; Lísal, Martin

2018-06-01

To address a high salinity of flow-back water during hydraulic fracturing, we use molecular dynamics (MD) simulations and study the thermodynamics, structure, and diffusion of concentrated aqueous salt solution in clay nanopores. The concentrated solution results from the dissolution of a cubic NaCl nanocrystal, immersed in an aqueous NaCl solution of varying salt concentration and confined in clay pores of a width comparable to the crystal size. The size of the nanocrystal equals to about 18 Å which is above a critical nucleus size. We consider a typical shale gas reservoir condition of 365 K and 275 bar, and we represent the clay pores as pyrophyllite and Na-montmorillonite (Na-MMT) slits. We employ the Extended Simple Point Charge (SPC/E) model for water, Joung-Cheatham model for ions, and CLAYFF for the slit walls. We impose the pressure in the normal direction and the resulting slit width varies from about 20 to 25 Å when the salt concentration in the surrounding solution increased from zero to an oversaturated value. By varying the salt concentration, we observe two scenarios. First, the crystal dissolves and its dissolution time increases with increasing salt concentration. We describe the dissolution process in terms of the number of ions in the crystal, and the crystal size and shape. Second, when the salt concentration reaches a system solubility limit, the crystal grows and attains a new equilibrium size; the crystal comes into equilibrium with the surrounding saturated solution. After crystal dissolution, we carry out canonical MD simulations for the concentrated solution. We evaluate the hydration energy, density profiles, orientation distributions, hydrogen-bond network, radial distribution functions, and in-plane diffusion of water and ions to provide insight into the microscopic behaviour of the concentrated aqueous sodium chloride solution in interlayer galleries of the slightly hydrophobic pyrophyllite and hydrophilic Na-MMT pores.

Concentrated aqueous sodium chloride solution in clays at thermodynamic conditions of hydraulic fracturing: Insight from molecular dynamics simulations.

PubMed

Svoboda, Martin; Lísal, Martin

2018-06-14

To address a high salinity of flow-back water during hydraulic fracturing, we use molecular dynamics (MD) simulations and study the thermodynamics, structure, and diffusion of concentrated aqueous salt solution in clay nanopores. The concentrated solution results from the dissolution of a cubic NaCl nanocrystal, immersed in an aqueous NaCl solution of varying salt concentration and confined in clay pores of a width comparable to the crystal size. The size of the nanocrystal equals to about 18 Å which is above a critical nucleus size. We consider a typical shale gas reservoir condition of 365 K and 275 bar, and we represent the clay pores as pyrophyllite and Na-montmorillonite (Na-MMT) slits. We employ the Extended Simple Point Charge (SPC/E) model for water, Joung-Cheatham model for ions, and CLAYFF for the slit walls. We impose the pressure in the normal direction and the resulting slit width varies from about 20 to 25 Å when the salt concentration in the surrounding solution increased from zero to an oversaturated value. By varying the salt concentration, we observe two scenarios. First, the crystal dissolves and its dissolution time increases with increasing salt concentration. We describe the dissolution process in terms of the number of ions in the crystal, and the crystal size and shape. Second, when the salt concentration reaches a system solubility limit, the crystal grows and attains a new equilibrium size; the crystal comes into equilibrium with the surrounding saturated solution. After crystal dissolution, we carry out canonical MD simulations for the concentrated solution. We evaluate the hydration energy, density profiles, orientation distributions, hydrogen-bond network, radial distribution functions, and in-plane diffusion of water and ions to provide insight into the microscopic behaviour of the concentrated aqueous sodium chloride solution in interlayer galleries of the slightly hydrophobic pyrophyllite and hydrophilic Na-MMT pores.

Spectroscopic mapping of the white horse alunite deposit, Marysvale volcanic field, Utah: Evidence of a magmatic component

USGS Publications Warehouse

Rockwell, B.W.; Cunningham, C.G.; Breit, G.N.; Rye, R.O.

2006-01-01

Previous studies have demonstrated that the replacement alunite deposits just north of the town of Marysvale, Utah, USA, were formed primarily by low-temperature (100??-170?? C), steam-heated processes near the early Miocene paleoground surface, immediately above convecting hydrothermal plumes. Pyrite-bearing propylitically altered rocks occur mainly beneath the steam-heated alunite and represent the sulfidized feeder zone of the H2S-dominated hydrothermal fluids, the oxidation of which at higher levels led to the formation of the alunite. Maps of surface mineralogy at the White Horse deposit generated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were used in conjunction with X-ray diffraction studies of field samples to test the accuracy and precision of AVIRIS-based mineral mapping of altered rocks and demonstrate the utility of spectroscopic mapping for ore deposit characterization. The mineral maps identified multiple core zones of alunite that grade laterally outward to kaolinite. Surrounding the core zones are dominantly propylitically altered rocks containing illite, montmorillonite, and chlorite, with minor pyrite, kaolinite, gypsum, and remnant potassium feldspar from the parent rhyodacitic ash-flow tuff. The AVIRIS mapping also identified fracture zones expressed by ridge-forming selvages of quartz + dickite + kaolinite that form a crude ring around the advanced argillic core zones. Laboratory analyses identified the aluminum phosphate-sulfate (APS) minerals woodhouseite and svanbergite in one sample from these dickite-bearing argillic selvages. Reflectance spectroscopy determined that the outer edges of the selvages contain more dickite than do the medial regions. The quartz + dickite ?? kaolinite ?? APS-mineral selvages demonstrate that fracture control of replacement processes is more prevalent away from the advanced argillic core zones. Although not exposed at the White Horse deposit, pyrophyllite ?? ordered illite was identified using AVIRIS in localized, superimposed conduits within propylitically altered rocks in nearby alteration systems of similar age and genesis that have been eroded to deeper levels. The fracture zones bearing pyrophyllite, illite, dickite, natroalunite, and/or APS minerals indicate a magmatic component in the dominantly steam-heated system. ?? 2006 Society of Economic Geologists, Inc.

Hydrothermal alteration maps of the central and southern Basin and Range province of the United States compiled from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data

USGS Publications Warehouse

Mars, John L.

2013-01-01

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and Interactive Data Language (IDL) logical operator algorithms were used to map hydrothermally altered rocks in the central and southern parts of the Basin and Range province of the United States. The hydrothermally altered rocks mapped in this study include (1) hydrothermal silica-rich rocks (hydrous quartz, chalcedony, opal, and amorphous silica), (2) propylitic rocks (calcite-dolomite and epidote-chlorite mapped as separate mineral groups), (3) argillic rocks (alunite-pyrophyllite-kaolinite), and (4) phyllic rocks (sericite-muscovite). A series of hydrothermal alteration maps, which identify the potential locations of hydrothermal silica-rich, propylitic, argillic, and phyllic rocks on Landsat Thematic Mapper (TM) band 7 orthorectified images, and geographic information systems shape files of hydrothermal alteration units are provided in this study.

A review of the surface features and properties, surfactant adsorption and floatability of four key minerals of diasporic bauxite resources.

PubMed

Zhang, Ningning; Nguyen, Anh V; Zhou, Changchun

2018-04-01

Diasporic bauxite represents one of the major aluminum resources. Its upgrading for further processing involves a separation of diaspore (the valuable mineral) from aluminosilicates (the gangue minerals) such as kaolinite, illite, and pyrophyllite. Flotation is one of the most effective ways to realize the upgrading. Since flotation is a physicochemical process based on the difference in the surface hydrophobicity of different components, determining the adsorption characteristics of various flotation surfactants on the mineral surfaces is critical. The surfactant adsorption properties of the minerals, in turn, are controlled by the surface chemistry of the minerals, while the latter is related to the mineral crystal structures. In this paper, we first discuss the crystal structures of the four key minerals of diaspore, kaolinite, illite, and pyrophyllite as well as the broken bonds on their exposed surfaces after grinding. Next, we summarize the surface chemistry properties such as surface wettability and surface electrical properties of the four minerals, and the differences in these properties are explained from the perspective of mineral crystal structures. Then we review the adsorption mechanism and adsorption characteristics of surfactants such as collectors (cationic, anionic, and mixed surfactants), depressants (inorganic and organic), dispersants, and flocculants on these mineral surfaces. The separation of diaspore and aluminosilicates by direct flotation and reverse flotation are reviewed, and the collecting properties of different types of collectors are compared. Furthermore, the abnormal behavior of the cationic flotation of kaolinite is also explained in this section. This review provides a strong theoretical support for the optimization of the upgrading of diaspore bauxite ore by flotation and the early industrialization of the reverse flotation process. Copyright © 2018 Elsevier B.V. All rights reserved.

Epithermal gold-siver deposits in the western United States: time-space products of evolving plutonic, volcanic and tectonic environments

USGS Publications Warehouse

Berger, Byron R.; Bonham, Harold F.

1990-01-01

The western United States has been the locus of considerable subaerial volcanic and plutonic igneous activity since the mid-Mesozoic. After the destruction of the Jurassic-Cretaceous magmatic arc-trench system, subduction was re-established in the Late Mesozoic with low-angle underthrusting of the oceanic plate beneath western North America. This resulted in crustal shortening during the Late Cretaceous to Early Tertiary and removal of the mantle lithosphere west of the Rocky Mountains. Commencing in the Eocene, flat subduction ceased, the volcanic arc began to re-establish itself along the continental margin, and the hingeline along the steepening subducting plate migrated from east to west. The crust east of the migrating hingeline was exposed to hot asthenosphere, and widespread tectonics and volcanic activity resulted. Hydrothermal activity accompanied the volcanism resulting in numerous epithermal gold-silver deposits. The temporal and spatial distributions of epithermal deposits in the region are therefore systematic and can be subdivided into discrete time intervals which are related to widespread changes in magmatic activity. Time intervals selected for discussion are Pre-Cenozoic, 66-55 Ma, 54-43 Ma, 42-34 Ma, 33-24 Ma, 23-17 Ma, and <17 Ma. Many of these intervals contain both sedimentary-rock and two varieties of volcanic-rock hosted deposits (adularia-sericite and alunite-kaolinite ± pyrophyllite). Continental rifting is important to the formation of deposits, and, within any given region, it is at the initiation of deep rifting that alunite-kaolinite ± pyrophyllite type epithermal deposits are formed. Adularia-sericite type deposits are most common, being related to all compositions and styles of volcanic activity. Therefore, the volcano-tectonic context of the western United States provides a unified framework in which to understand and explore for epithermal type deposits.

Geology and reconnaissance stable isotope study of the Oyu Tolgoi porphyry Cu-Au system, South Gobi, Mongolia

USGS Publications Warehouse

Khashgerel, B.-E.; Rye, R.O.; Hedenquist, J.W.; Kavalieris, I.

2006-01-01

The Oyu Tolgoi porphyry Cu-Au system in the South Gobi desert, Mongolia, comprises five deposits that extend over 6 km in a north-northeast-oriented zone. They occur in a middle to late Paleozoic are terrane and are related to Late Devonian quartz monzodiorite intrusions. The Hugo Dummett deposits are the northernmost and deepest, with up to 1,000 m of premineral sedimentary and volcanic cover rock remaining. They are the largest deposits discovered to date and characterized by high-grade copper (>2.5% Cu) and gold (0.5-2 g/t) mineralization associated with intense quartz veining and several phases of quartz monzodiorite intruded into basaltic volcanic host rocks. Sulfide minerals in these deposits are zoned outward from a bornite-dominated core to chalcopyrite, upward to pyrite ?? enargite and covellite at shallower depth. The latter high-sulfidation-state sulfides are hosted by advanced argillic alteration mineral associations. This alteration is restricted mainly to dacitic ash-flow tuff that overlies the basaltic volcanic rock and includes ubiquitous quartz and pyrophyllite, kaolinite, plus late dickite veins, as well as K alunite, Al phosphate-sulfate minerals, zunyite, diaspore, topaz, corundum, and andalusite. A reconnaissance oxygen-hydrogen and sulfur isotope study was undertaken to investigate the origin of several characteristic alteration minerals in the Oyu Tolgoi system, with particular emphasis on the Hugo Dummett deposits. Based on the isotopic composition of O, H, and S (??18O(SO4) = 8.8-20.1???, ??D = -73 to -43???, ??34S = 9.8-17.9???), the alunite formed from condensation of magmatic vapor that ascended to the upper parts of the porphyry hydrothermal system, without involvement of significant amounts of meteoric water. The isotopic data indicate that pyrophyllite (??18O = 6.5-10.9???, ??D = -90 to -106???) formed from a magmatic fluid with a component of meteoric water. Muscovite associated with quartz monzodiorite intrusions occurs in the core of the Hugo Dummett deposits, and isotopic data (??18O = 3.0-9.0???, ??D = -101 to -116%o) show it formed from a magmatic fluid with water similar in composition to that which formed the pyrophyllite. Mg chlorite (??18O = 5.5???, ??D = -126???) is a widespread mineral retrograde after hydrothermal biotite and may have formed from fluids similar to those related to the muscovite during cooling of the porphyry system. By contrast, paragenetically later and postmineralization alteration fluid, which produced dickite (??18O = -4.1 to +3.3???, ??D = -130 to -140???), shows clear evidence for mixing with substantial amounts of meteoric water. Relatively low ??D values (-140???) for this meteoric water component may indicate that its source was at high elevations. The geologic structure, nature of alteration, styles of mineralization, and stable isotope data indicate that the Oyu Tolgoi deposits constitute a typical porphyry system formed in an island-arc setting. The outward zonation of sulfide minerals for the Hugo Dummett deposits, from a bornite-dominated core to chalcopyrite and pyrite-enargite, can be interpreted to be related to a cooling magmatic hydrothermal system which transgressed outward over enclosing advanced argillic alteration. This resulted in some unusual alteration and sulfide parageneses, such as topaz, or pyrite, enargite, and tennantite, entrained by high-grade bornite. ?? 2006 by Economic Geology.

Molecular Simulation of Cesium Adsorption at the Basal Surface of Phyllosilicate Minerals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerisit, Sebastien N.; Okumura, Masahiko; Rosso, Kevin M.

2016-08-16

A better understanding of the thermodynamics of radioactive cesium uptake at the surfaces of phyllosilicate minerals is needed to understand mechanisms of its selective adsorption and help guide the development of practical and inexpensive decontamination techniques. In this work, molecular dynamics simulations were carried out to determine the thermodynamics of adsorption of Cs + at the basal surface of six 2:1 phyllosilicate minerals, namely pyrophyllite, illite, muscovite, phlogopite, celadonite, and margarite. These minerals were selected to isolate the effects of the magnitude of the permanent layer charge (≤ 2), its location (tetrahedral versus octahedral sheet), and the structure of themore » octahedral sheet (dioctahedral versus trioctahedral). Good agreement was obtained with experiment in terms of the hydration free energy of Cs + and the structure and thermodynamics of Cs + adsorption at the muscovite basal surface, for which published data were available for comparison. With the exception of pyrophyllite, which did not exhibit an inner-sphere free energy minimum, all phyllosilicate minerals showed similar behavior with respect to Cs + adsorption; notably, Cs + adsorption was predominantly inner-sphere whereas outer-sphere adsorption was very weak with the simulations predicting the formation of an extended outer-sphere complex. For a given location of the layer charge, the free energy of adsorption as an inner-sphere complex was found to vary linearly with the magnitude of the layer charge. For a given location and magnitude of the layer charge, adsorption at phlogopite (trioctahedral sheet structure) was much less favorable than at muscovite (dioctahedral sheet structure) due to the electrostatic repulsion between the adsorbed Cs + and the hydrogen atom of the hydroxyl group directly below the six-membered siloxane ring cavity. For a given magnitude of the layer charge and structure of the octahedral sheet, adsorption at celadonite (layer charge located in the octahedral sheet) was favored over muscovite (layer charge located in the tetrahedral sheet) due to the increased distance with surface potassium ions.« less

The regulation of crystalline silica: an industry perspective.

PubMed

Elzea, J M

1997-01-01

Silica is ubiquitous in the earth's crust. It occurs in trace to large quantities in rocks and soil. Because it is so common, the regulation of silica has affected a large number of industries, including the mining industry and any industry that uses quartz in the manufacture of a products. Mineral commodities that contain silica include diatomite, bentonite, kaolinite, talc, pyrophyllite, sand and gravel, perlite, pumice, dimension stone, and barite. Products that contain minerals, many of which are associated with silica, include paint, paper, rubber, plastic, pharmaceuticals, food, cement, plaster, cat litter, potting soil, plaster board, and miscellaneous construction materials. In collaboration with some agencies and academic centers, the silica industry is supporting research to lower health risks and to improve the methods of detecting this common material.

Retention of contaminants Cd and Hg adsorbed and intercalated in aluminosilicate clays: A first principles study

NASA Astrophysics Data System (ADS)

Crasto de Lima, F. D.; Miwa, R. H.; Miranda, Caetano R.

2017-11-01

Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ˜20 and ˜130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays.

Occurrences of alunite, prophyllite, and clays in the Cerro La Tiza area, Puerto Rico

USGS Publications Warehouse

Hildebrand, Fred Adelbert; Smith, Raymond J.

1959-01-01

A deposit of hydrothermally altered rocks in the Cerro La Tiza area located between the towns of Comerio and Aguas Buenas, approximately 25 kilometers southwest of San Juan, Puerto Rico, was mapped and studied to determine the principal minerals, their extent distribution and origin, and the possibility of their economic utilization, especially in Puerto Rico. The Cerro la Tiza area is about 7? kilometers long, has an average width of about 1? kilometers and embraces a total area of approximately 15 square kilometers. The principal mineralized zone, a dike-like mass of light-colored rocks surrounded by dark-colored volcanic country rocks, occupies the crest and upper slopes of east-trending Cerro La Tiza ridge and is believed to be of Late Cretaceous or Eocene age. This zone is approximately 5,300 meters long, 430 meters wide and has an area of approximately 225 hectares (556 acres). The rocks of the mineralized zone are of mixed character and consist mainly of massive quartzose rocks and banded quartz-alunite rocks closely associated with foliated pyrophyllitic, sericitic and clayey rocks. The principal minerals in probably order of abundance are quartz, alunite, pyrophyllite, kaolin group clays (kaolinite and halloysite) and sericite. Minerals of minor abundance are native sulfure, diaspore, svanbergite (?), sunyite (?), hematite, goethite, pyrite, rutile (?) and very small quantities of unidentified minerals. The mineralized zone has broken down to deposits of earth-rock debris of Quaternary age that cover much of the slopes and flanks of Cerro La Tiza. This debris consists generally of fragments and boulders with a very large size range embedded in a clayey matrix. The distribution of the earth-rock debris with respect to the present topography and drainage suggests that it may have undergone at least two cycles of erosion. Underlying the earth-rock debris and completely enclosing the mineralized zone are country rocks of probably Late Cretaceous age. These consist principally of low flows and volcanic and flow breccias but contain thin interbedded siltstones and sandstones. The lavas are generally predominant at the western end of the area and the breccias at the eastern end. The mineralized zone and the country rocks are sheared along two predominant directions that are approximately N 70 degrees E and N 70 degrees W. The ridge of Cerro La Tiza appears to be a broad shear zone through which hydrothermal emanations gained access to the country rocks. The emanations are believed to have originated from intrusive rocks that probably underlie the area. The surrounding area contains both large and small exposed intrusive bodies. The largest one is the San Lorenzo batholith of Late Cretaceous or Eocene age whose exposed northwest edge is approximately 19 kilometers southeast of the eastern end of the Cerro La Tiza area. Other zones of hydrothermally altered rocks were discovered along a mineralized belt extending eastward from Cerro La Tiza through the Rio Gurabo Valley nearly to the Vieques Passage bordering the east coast of Puerto Rico. Other zones were discovered north and south of this belt and still others were found circumventing the San Lorenzo batholith. The most abundant minerals of the mineralized zone can be exploited for economic utilization in Puerto Rico. Alunite can be utilized in the manufacture of aluminum sulfate for water purification. It can also be used in the manufacture of alumina refractory materials. Pyrophyllite can be used as a carrier for insecticides and fungicides. It can also be utilized for the manufacture of ceramic products, as a filler in the soap industry and as a carrier for paint pigments. Kaolinite can be used in the ceramic industry and in the manufacture of glass as a substitute for feldspar. Halloysite might be utilized as a catalyst support in the cracking of petroleum. Tonnages of reserve ore on Cerro La Tiza are calculated to be 1,590,000 inferred short tons (1,4

Driving forces for metamorphic vein filling during bauxite dehydration: insights from Li and Al transfer illustrated by LIBS compositional profiles (Western Alps)

NASA Astrophysics Data System (ADS)

Verlaguet, Anne; Brunet, Fabrice; Goffé, Bruno; Menut, Denis; Findling, Nathaniel; Poinssot, Christophe

2015-04-01

In subduction zones, the significant amounts of aqueous fluid released in the course of the successive dehydration reactions occurring during prograde metamorphism are expected to strongly influence the rock rheology, as well as kinetics of metamorphic reactions and mass transfer efficiency. Mineralized veins, ubiquitous in metamorphic rocks, can be seen as preserved witnesses of fluid and mass redistribution that partly accommodate the rock deformation (lateral segregation). However, the driving forces and mechanisms of mass transfer towards fluid-filled open spaces remain somewhat unclear. The aim of this study is to investigate the vein-forming processes and the modalities of mass transfer during local fluid-rock interactions, and their links with fluid production and rock deformation, with new insights from Laser Induced Breakdown Spectroscopy (LIBS) profiles. This study focuses on karstic pockets (metre scale) of Triassic metabauxites embedded in thick carbonate units, that have been isolated from large-scale fluid flow during HP-LT Alpine metamorphism (W. Vanoise, French Alps). These rocks display several generations of metamorphic veins containing various Al-bearing minerals, which give particular insights into mass transfer processes. It is proposed that the internally-derived fluid (~13 vol% produced by successive dehydration reactions) has promoted the opening of fluid-filled open spaces (euhedral habits of vein minerals) and served as medium for diffusive mass transfer from rock to vein. Based on mineralogical and textural features, two vein types can be distinguished: (1) some veins are filled with newly formed products of either prograde (chloritoid) or retrograde (chlorite) metamorphic reactions; in this case, fluid-filled open spaces seem to offer energetically favourable nucleation/growth sites; (2) the second vein type is filled with cookeite (Li-Al-rich chlorite) or pyrophyllite, which were present in the host-rock prior to the vein formation. In this closed chemical system, mass transfer from rock to vein was achieved through the fluid, in a dissolution-transport-precipitation process. To investigate the modalities of mass transfer towards this second vein type, LIBS profiles were performed in the host-rock, taking Li concentration as a proxy for cookeite distribution. Cookeite is highly concentrated (45-65 vol%) in regularly spaced veins, and the LIBS profiles show that cookeite is evenly distributed in the host-rock comprised between two veins. The absence of diffusion profiles suggests that the characteristic diffusion distance for Li, Al and Si is greater than or equal to the distance separating two cookeite veins (2-4 cm). This is in agreement with characteristic diffusion lengths calculated from both grain boundary and pore fluid diffusion coefficients, for the estimated duration of the peak of metamorphism. Which driving forces are responsible for cookeite selective transfer towards veins? Chemical potential gradients between host-rock pores and veins may have developed in response to either (1) a stress difference: thermochemical calculations show that pressure-solution processes may affect preferentially cookeite and pyrophyllite; (2) a difference in interfacial energy, phyllosilicates showing very different morphologies in host-rocks (fibers) compared to veins (euhedral crystals); fluid-mineral interfacial energy may be maximal in the small host-rock pores, which can maintain higher cookeite solubility than large fluid-filled open spaces (i.e., veins).

Electrospinning β-SiC fibers from SiC nanoparticles dispersed in various polymer solutions as the electrospinning agents

NASA Astrophysics Data System (ADS)

Fuad, A.; Fatriani, N.; Yogihati, C. I.; Taufiq, A.; Latifah, E.

2018-04-01

Silicon carbide (SiC) fibers were synthesized by electrospinning method from SiC nanoparticles dispersed in polymer solutions, i.e., polyethylene glycol (PEG) and polyvinyl alcohol (PVA). The SiC nanoparticle used in this research was synthesized from sucrose and natural silica via a sonochemical method. The natural silica was extracted from local pyrophyllite by a sol-gel method. The characterization was performed via x-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM). The XRD characterization results showed that the sample possessed a β-SiC phase and formed a cubic-structured crystal with a lattice parameter of a = b = c = 4.3448 Å. The use of PEG and PVA in the electrospinning process resulted in fractal and fiber structured SiC, respectively.

Short-wave infrared reflectance investigation of sites of paleobiological interest: applications for Mars exploration.

PubMed

Brown, Adrian; Walter, Malcolm; Cudahy, Thomas

2004-01-01

Rover missions to the rocky bodies of the Solar System and especially to Mars require lightweight, portable instruments that use minimal power, require no sample preparation, and provide suitably diagnostic mineralogical information to an Earth-based exploration team. Short-wave infrared (SWIR) spectroscopic instruments such as the Portable Infrared Mineral Analyser (PIMA, Integrated Spectronics Pty Ltd., Baulkham Hills, NSW, Australia) fulfill all these requirements. We describe an investigation of a possible Mars analogue site using a PIMA instrument. A survey was carried out on the Strelley Pool Chert, an outcrop of stromatolitic, silicified Archean carbonate and clastic succession in the Pilbara Craton, interpreted as being modified by hydrothermal processes. The results of this study demonstrate the capability of SWIR techniques to add significantly to the geological interpretation of such hydrothermally altered outcrops. Minerals identified include dolomite, white micas such as illite-muscovite, and chlorite. In addition, the detection of pyrophyllite in a bleached and altered unit directly beneath the succession suggests acidic, sulfur-rich hydrothermal activity may have interacted with the silicified sediments of the Strelley Pool Chert.

Altered rock spectra in the visible and near infrared. [western Nevada

NASA Technical Reports Server (NTRS)

Hunt, G. R.; Ashley, R. P. (Principal Investigator)

1979-01-01

The author has identified the following significant results. Visible and near-infrared (0.35 to 2.5 micron m) bidirectional reflection spectra recorded for a suite of well-characterized hydrothermally altered rock samples typically display well defined bands caused by both electronic and vibrational processes in the individual mineral constituents. Electronic transitions in the iron-bearing constituent minerals produce diagnostic minima near 0.43, 0.65, 0.85, and 0.93 micron m. Vibrational transitions in clay and water-bearing mineral constituents produce characteristic single or multiple features over limited spectral ranges near 1.4, 1.75, 1.9, 2.2, and 2.35 micron m. The most abundant feature-producing minerals present in these rocks are hematite, goethite, and alunite. Others frequently present are jarosite, kaolinite, potassium micas, pyrophyllite, montmorillonite, diaspore, and gypsum. The spectral region near 2.2 micron m is particularly important for detecting altered rocks by remote sensing.

Measuring the isoelectric point of the edges of clay mineral particles: the case of montmorillonite.

PubMed

Pecini, Eliana M; Avena, Marcelo J

2013-12-03

The isoelectric point (IEP) of the edge surface of a montmorillonite sample was determined by using electrophoretic mobility measurements. This parameter, which is fundamental for the understanding of the charging behavior of clay mineral surfaces, was never measured so far because of the presence of permanent negative charges within the montmorillonite structure, charges that mask the electrokinetic behavior of the edges. The strategy was to block or neutralize the structural charges with two different cations, methylene blue (MB(+)) and tetraethylenepentaminecopper(II) ([Cu(tetren)](2+)), so that the charging behavior of the particles becomes that of the edge surfaces. Adsorption isotherms of MB(+) and [Cu(tetren)](2+) at different ionic strengths (NaCl) were performed to establish the uptakes that neutralize the cation exchange capacity (CEC, 0.96 meq g(-1)) of the sample. At high adsorptive concentrations, there was a superequivalent adsorption of MB(+) (adsorption exceeding the CEC) and an equivalent adsorption of [Cu(tetren)](2+) (adsorption reaching the CEC). In both cases, structural charges were neutralized at uptakes very close to the CEC. Zeta potential (ζ) vs pH data at different ionic strengths of montmorillonite with adsorbed MB(+) allowed to estimate an upper limit of the edge's IEP, 5.3 ± 0.2. The same kind of data obtained with adsorbed [Cu(tetren)](2+) provided a lower limit of the IEP, 4.0 ± 0.2. These values are in agreement with previously informed IEP and point of zero charge of pyrophyllite, which is structurally analogous to montmorillonite but carries no permanent charges. The importance of knowing the IEP of the edge surface of clay minerals is discussed. This value characterizes the intrinsic reactivity of edges, that is, the protonating capacity of edge groups in absence of any electric field generated by structural charges. It also allows us to correct relative edge charge vs pH curves obtained by potentiometric titrations and to obtain the true edge charge vs pH curves at different electrolyte concentrations.

Molecular dynamics simulation of thermomechanical properties of montmorillonite crystal. 1. Isolated clay nanoplate.

PubMed

Mazo, Mikhail A; Manevitch, Leonid I; Gusarova, Elena B; Shamaev, Mikhail Yu; Berlin, Alexander A; Balabaev, Nikolay K; Rutledge, Gregory C

2008-03-13

The structure and mechanical properties of clay nanoparticles is a subject of growing interest because of their numerous applications in engineering. We present the results of molecular dynamics simulation for a single nanoplate of pyrophyllite - a 2:1 clay mineral consisting of two tetrahedral sheets of SiO4 and an intervening octahedral AlO6 sheet. Simulations were performed in the temperature interval from 5 to 750 K using the ionic-type potentials of Cygan et al. On this basis the temperature dependences of structural parameters, characterizing both tetrahedral and octahedral sheets as well as single lamella, have been studied. Two slightly different structures were observed in this wide temperature interval. The mechanical properties of the nanoplate were calculated from stress-strain diagrams, which have been obtained at relatively slow rates of deformation (for molecular simulations). Using different types of loading, we calculated the full elasticity tensor and estimated the influence of temperature on its components. We estimated also the bending and torsion stiffnesses of the nanoplate as specific characteristics of this type of particle. Because the nanoplate is atomically thin, a reasonable determination of the thickness is a nontrivial problem, both in the modeling of mechanical properties and in physical interpretation of the obtained data. We propose a procedure for its calculation.

Palaeozoic gas charging in the Ahnet-Timimoun basin, Algeria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cawley, S.J.; Wilson, N.P.; Primmer, T.

1995-08-01

The Ahnet-Timimoun Basin, Southern Algeria, contains significant gas reserves expelled from originally oil prone Silurian and Frasnian shales. The gas is reservoired in Devonian and Carboniferous clastics in inversion anticlines formed, primarily, during the Hercynian orogeny. Integration of organic and inorganic geochemical techniques, such as AFTA, ZFTA, fluid inclusion analysis, vitrinite and chitinizoan reflectance, is entirely consistent with gas generation 300 +/- 30MY, immediately prior to or synchronous with the Hercynian orogeny. Data from gas fields has shown the remobilisation of gas during post Hercynian tectonics. A {open_quotes}two-event{close_quotes} heating/cooling history is proposed: (1) Maximum burial and palaeotemperature at ca. 300more » +/- 30MY prior to or synchronous with Hercynian uplift and cooling. (2) Cooling from a secondary peak (lower than maximum) palaeotemperature at ca. 30-60My following Creataceous burial. Calibrated thermal modelling indicates that Palaeozoic source rocks were heated above 200{degrees}C in the Late Carboniferous. Such high temperatures are consistent with the widespread occurrence of pyrophyllite in Silurian shales. Two end-member thermal models can account for the observed maturities. The first is a constant high Pre-Hercynian heat flow which rapidly decreases during Hercynian uplift to remain at Present day values of 50-75mW/m{sup 2}. Gas expulsion in this case commences much earlier than trap formation. The second is {open_quotes}normal{close_quotes} heat flow of ca. 50mW/m{sup 2} until ca. 310My with a rapid increase at ca. 290My followed by an equally rapid drop to constant present day values - in this model, petroleum generation and expulsion is late in relation to structuring.« less

Exploration for gold mineralization in the Arabo Nubian Shield: Using remote sensing Approach

NASA Astrophysics Data System (ADS)

Ramadan, Talaat

2013-04-01

In the southern part of the Eastern Desert of Egypt, Landsat Thematic Mapper (ETM+) data and fieldwork was combined with mineralogical and geochemical investigations in order to detect and characterize alteration zones within Pan-African rocks. The processing of Landsat ETM+ data using ratioing (bands 5/7,5/1,4/3 in Red, Green, Blue) showed two different types of alteration zones (type l and 2). Type 1 is close to the ophiolitic ultramafic rocks and type 2 is located within island-arc related metavolcanic rocks at the study areas. Both of these alteration zones are concordant with the main NW-SE structural trend. Mineralogical studies indicate that the alteration zones of type 1 consist mainly of calcite, ankerite, magnesite, dolomite and quartz. Chromian spinel, pyrite, and Ni-bearing sulphides (gersdorffite, pentlandite and polydymite) are the main ore minerals within this zone. Alteration zones of type 2 are strongly potassium-enriched and pyrophyllite, kaolinite, illite, gypsum and quartz occur. The brecciated quartz-veins associated with theses alteration zones consist of quartz, Fe-hydroxides, hematite and native gold. The gold content reaches up to 5 g/t in the alteration zone, while it extends up to 50 g/t in the quartz veins. This study presents a mineralogical characterization of such zones and demonstrates the utility of orbital remote sensing for finding unknown alteration zones in the Eastern Desert and other arid areas with similar host rock lithologies.

Anisometric Particle Systems—from Shape Characterization to Suspension Rheology

NASA Astrophysics Data System (ADS)

Gregorová, Eva; Pabst, Willi; Vaněrková, Lucie

2009-06-01

Methods for the characterization of anisometric particle systems are discussed. For prolate particles, the aspect ratio determination via microscopic image analysis is recalled, and aspect ratio distributions as well as shape-size dependences are commented upon. For oblate particles a simple relation is recalled with can be used to determine an average aspect ratio when size distributions are available from two methods, typically from sedimentation analysis and laser diffraction. The connection between particle shape (aspect ratio) and suspension rheology is outlined and it is shown how a generic procedure, based on Brenner's theory, can be applied to predict the intrinsic viscosity when the aspect ratio is known. On the other hand it is shown, how information on the intrinsic viscosity and the critical solids volume fraction can be extracted from experiments, when the measured concentration dependence of the effective suspension viscosity is adequately interpreted (using the Krieger relation for fitting). The examples mentioned in this paper include systems with oblate or prolate ceramic particles (kaolins, pyrophyllite, wollastonite, silicon carbide) as well as (prolate) pharmaceuticals (mesalamine, ibuprofen, nifuroxazide, paracetamol).

Experimental measurements of shock properties of stishovite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furnish, M.D.; Ito, E.

1995-10-01

We have synthesized, characterized and performed Hugoniot measurements on monolithic samples of stishovite, a high pressure polymorph of silica. Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed by NMR analysis. They had no significant impurities except less than 1% carbon. Samples {approximately} 1 mm thick and 3 mm diameter were tested in reverse- and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec.more » Hugoniot stresses for the four successful tests ranged from 65 to 225GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanariy issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used.« less

Experimental measurements of shock properties of stishovite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furnish, M.D.; Ito, E.

1996-05-01

We have synthesized, characterized and performed Hugoniot measurements on monolithic samples of stishovite. Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07Mg/m{sup 3}, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed by NMR analysis. They had no significant impurities except less than 1{percent} carbon. Samples {approximately}1 mm thick and 3 mm diameter were tested in reverse- and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec. Hugoniot stresses for the four successfulmore » tests ranged from 65 to 225GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanarity issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used. {copyright} {ital 1996 American Institute of Physics.}« less

Laboratory Far-infrared Spectroscopy Of Terrestrial Phyllosilicates To Support Analysis Of Cosmic Dust Spectra.

NASA Astrophysics Data System (ADS)

Yesiltas, Mehmet; Brusentsova, T.; Peale, R.; Maukonen, D.; Figueiredo, P.; Harlow, G. H.; Ebel, D. S.; Nissinboim, A.; Sherman, K.; Lisse, C. M.

2012-01-01

Poster Abstract: 219th AAS Meeting M. Yesiltas1, T. Brusentsova1, R. E. Peale1, D. Maukonen1, P. Figueiredo1, G. E. Harlow2, D. S. Ebel2, A. Nissinboim2, K. Sherman2, and C. M. Lisse3 Remote spectral detection of hydrated minerals is of general interest in the solar system and dusty circumstellar disks. This paper presents spectroscopy of terrestrial phyllosilicate minerals in the wavelength range 15 - 250 µm to support interpretation of returned data from far-IR space-missions such as the Herschel Space Observatory. The far-IR spectral region beyond 15 micron wavelength is especially diagnostic of mineral composition and crystal structure. Relatively little far-IR spectral data exists in the literature on suitably-characterized naturally-occurring phyllosilicate minerals in the wavelength range 60-210 microns corresponding to the PACS instrument of Herschel Space Observatory. Extending the database of laboratory far-IR spectra of terrestrial mineral analogs is therefore desirable and timely. Seventeen phyllosilicate minerals expected in various astronomical environments were sampled from the American Museum of Natural History for diversity and astrophysical relevancy, based on their identification in Stardust, in stratospheric IDP samples, or in meteorites. These include serpentines (Antigorite and Chrysotile), smectites (Talc, Pyrophyllite, Vermiculite, Montmorillonite, Beidellite, Saponite, Nontronite and Hectorite), chlorites (Clinochlore), micas (Muscovite, Paragonite, Margarite, Clintonite, Biotite and Illite), and kaolinites (Dickite, Nacrite, Kaolinite, Halloysite, Attapulgite and Sepiolite). Spectra of micron-sized powder suspensions in polyethelyne pellets reveal prominent and characteristic far-IR features, which differ significantly in some cases from already published spectra, where available. Acknowledgements : This research was supported by NASA-JPL Contract # 1327221. 1Department of Physics, University of Central Florida, Orlando FL 32816 USA2American Museum of Natural History, New York NY 10024 USA3Johns Hopkins University Applied Physics Laboratory, Laurel MD 20723 USA

Comparison between the fluid characteristics of the Rodalquilar and two neighbouring epithermal gold deposits in Spain

NASA Astrophysics Data System (ADS)

Sänger-von Oepen, P.; Friedrich, G.; Kisters, A.

1990-12-01

The operating Rodalquilar gold deposit and the abandoned Triunfo and Maria Josefa gold mines are located within the Sierra del Cabo de Gata volcanic field some 40 km east of Almeria in SE Spain. While the gold mineralization at Rodalquilar is mainly controlled by caldera-tectonics, vein structures at Triunfo and Maria Josefa are not. Wall-rock alteration at Triunfo and Maria Josefa is characterized by argillic alteration (illite/sericite, kaolinite). The alteration zonation around the gold-mineralized vein structures at Rodalquilar ranges from advanced argillic alteration (porous quartz, alunite, pyrophyllite, dickite) over argillic alteration into a regionally developed propylitization. Fluid inclusion studies from all three mines indicate that gold was deposited from low-salinity fluids (2 5 wt.% NaCl equivalent) between 170° and 250 °C. However, the hydrothermal system at Rodalquilar was fed by a second fluid source. High-salinity, halite and/or sylvite-bearing, liquid-rich, and vapour-dominated, CO2-bearing fluid inclusions are assumed to be of magmatic origin. High sulfidation ore mineral assemblages at depth (covellite, enargite, tennantite) and part of the advanced argillic alteration can be related to these fluids. Thus, part of those features which attribute the Rodalquilar gold deposit to the acid-sulfate or high sulfidation type of epithermal gold deposits, stem from magmatically derived fluids which are typical for a porphyry environment, whereas gold mineralization at all three localities is associated with low-salinity fluids, probably of marine origin.

Development of Kawai-type multianvil technology using nano-polycrystalline diamond anvils

NASA Astrophysics Data System (ADS)

Irifune, T.; Kunimoto, T.

2016-12-01

Nano-polycrystalline diamond (NPD) developed at GRC, Ehime Univ., is known to be much harder than conventional sintered polycrystalline diamond (SD), and is potentially important as material for anvils for Kawai-type (6-8 type) multianvil apparatus (KMA), as well as for diamond anvil cell. We synthesized NPD rods with about 8 mm in both diameter and length using a 6000-ton press KMA (BOTCHAN-6000), which are cut by pulsed-laser to form cubes with 6 mm edge length and tested them as anvils for KMA. In situ X-ray observations were made to evaluate the produced pressures and sample images using the "6-6-8 assembly". A combination of semi-fired pyrophyllite gaskets and alumina ceramics pressure medium optimized for the NPD anvils with a truncation (TEL) of 1.0 mm yielded pressures up to 88 GPa at a press load of only 3.4 MN, which is nearly 60% higher than the pressure (56 GPa) reached using SD anvils with the identical cell assembly at the same press load. Moreover, the high X-ray transparency of NPD has enabled us to clearly see the sample image via the anvils, allowing diffraction measurements and observations of the sample shape even if the anvil gap becomes very small under such very high pressures. The use of NPD anvils should lead to new technology for mineral physics studies under the conditions of the Earth's lowermost mantle and possibly those of the core without scarifying the advantages of KMA over DAC.

Acid-base properties of 2:1 clays. I. Modeling the role of electrostatics.

PubMed

Delhorme, Maxime; Labbez, Christophe; Caillet, Céline; Thomas, Fabien

2010-06-15

We present a theoretical investigation of the titratable charge of clays with various structural charge (sigma(b)): pyrophyllite (sigma(b) = 0 e x nm(-2)), montmorillonite (sigma(b) = -0.7 e x nm(-2)) and illite (sigma(b) = -1.2 e x nm(-2)). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a perfect hexagonal platelet, with an "ideal" crystal structure. The only fitting parameters used are the intrinsic equilibrium constants (pK(0)) for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces of the clay particles, silanol, =SiO(-) + H(+) --> =SiOH, and aluminol, =AlO(-1/2) + H(+) --> =AlOH(+1/2). Simulations are found to give a satisfactory description of the acid-base titration of montmorillonite without any additional fitting parameter. In particular, combining the electrostatics from the crystal substitutions with ionization constants, the simulations satisfactorily catch the shift in the titration curve of montmorillonite according to the ionic strength. Change in the ionic strength modulates the screening of the electrostatic interactions which results in this shift. Accordingly, the PZNPC is found to shift toward alkaline pH upon increasing the permanent basal charge. Unlike previous mean field model results, a significant decrease in PZNPC values is predicted in response to stack formation. Finally, the mean field approach is shown to be inappropriate to study the acid-base properties of clays.

High pressure generation using scaled-up Kawai-cell

NASA Astrophysics Data System (ADS)

Shatskiy, A.; Katsura, T.; Litasov, K. D.; Shcherbakova, A. V.; Borzdov, Y. M.; Yamazaki, D.; Yoneda, A.; Ohtani, E.; Ito, E.

2011-11-01

A scaled-up version of a 6-8 Kawai-type multianvil apparatus equipped with 47-mm WC anvils has been developed at the Institute for the Study of the Earth's Interior for operation over pressure ranging up to 19 and 24 GPa using the conventional system with larger compressional volumes between 1.2 and 0.4 cm 3, respectively. This system is used under uniaxial compression along cube diagonal of the Kawai-cell up to the press load of 19 MN. Experiments are performed using octahedral pressure media (PM) made of MgO- and ZrO 2-based semi-sintered ceramics and unfired pyrophyllite gaskets. In this study we used "Toshiba-F" grade WC anvils allowing pressure generation up to 24 GPa. We perform pressure calibrations at room and high temperatures, with octahedron/anvil truncation edge-length ratios ( a0/ b, mm) of 12.2/6, 14/6, 14/7, 16/7, 18/7, 18/9, and 18/10. Different configurations show that an increase in edge-length ratio of a0/b permits the achievement of higher pressure, which agrees with the results of Frost at al. (Frost, D.J., Poe, B.T., Tronnes, R.G., Liebske, C., Duba, A., Rubie, D.C., 2004. A new large-volume multianvil system. Phys. Earth Planet. Inter. 143, 507). However, it also shifts the pressure maximum to higher press loads, in some cases exceeding the capacity of a press. Our and Frost et al. (2004) data reveal that the 14/6, 18/8, and 18/10 assemblies are the most suitable in generating pressures of up to 19-24 GPa at 19 MN press load limits. The assemblies with a low a0/ b ratio have a lower upper pressure limit; however, they exhibit a systematically higher efficiency in pressure generation at low press loads. Consequently, assemblages with high and low a0/ b ratios should be used in high and low pressure experiments, respectively. For example, the 18/12 assembly is suitable for 5-11 GPa pressure range (Stoyanov, E., Haussermann, U., Leinenweber, K., 2010. Large-volume multianvil cells designed for chemical synthesis at high pressures. High Pressure Res., 30, 175), whereas the 14/6, 18/8 ( Frost et al., 2004), and 18/10 assemblies are suitable for 22-24, 19-23, and 11-19 GPa pressure ranges, respectively. The maximum pressure generation achieved in the present study is 24 GPa, using the 14/6 assembly. This appears to be the maximum pressure level attainable by using WC anvils.

Radioactivity in books printed in Japan: its source and relation to the year of issue.

PubMed

Kobashi, A

1996-06-01

The radioactivities of the naturally occurring radionuclides (226Ra, 228Ra, 228Th and 40K) and a fallout nuclide (137Cs) in books produced in Japan in the 20th century were measured by gamma-ray spectrometry to obtain information on radiation emitted from books. The respective concentration ranges of 226Ra, 228Ra, 228Th, 40K, and 137Cs were 0.2-6.4, 0.4-11.2, 0.3-11.3, 1-112, and 0-3 Bq kg-1. X-ray diffraction spectra of the papers used in book printing showed that pyrophyllite, talc, kaolinite, and calcium carbonate were contained as fillers. A comparison of the radioactivity contents of the pulp and filler indicated that most of 226Ra, 228Ra, and 228Th in the books was present in the filler whereas 137Cs was in the pulp. The pattern of the concentration of each nuclide vs. the year of issue of the book was investigated. Patterns for the naturally occurring radionuclides were similar and were explained by the kinds of filler used. The pattern for 137Cs differed from the patterns of the naturally occurring radionuclides, having a marked peak in the mid-1960s.

Production of Ultrafine, High-purity Ceramic Powders Using the US Bureau of Mines Developed Turbomill

NASA Technical Reports Server (NTRS)

Hoyer, Jesse L.

1993-01-01

Turbomilling, an innovative grinding technology developed by the U.S. Bureau of Mines in the early 1960's for delaminating filler-grade kaolinitic clays, has been expanded into the areas of particle size reduction, material mixing, and process reaction kinetics. The turbomill, originally called an attrition grinder, has been used for particle size reduction of many minerals, including natural and synthetic mica, pyrophyllite, talc, and marble. In recent years, an all-polymer version of the turbomill has been used to produce ultrafine, high-purity, advanced ceramic powders such as SiC, Si3N4, TiB2, and ZrO2. In addition to particle size reduction, the turbomill has been used to produce intimate mixtures of high surface area powders and whiskers. Raw materials, TiN, AlN, and Al2O3, used to produce a titanium nitride/aluminum oxynitride (TiN/AlON) composite, were mixed in the turbomill, resulting in strength increases over samples prepared by dry ball milling. Using the turbomill as a leach vessel, it was found that 90.4 pct of the copper was extracted from the chalcopyrite during a 4-hour leach test in ferric sulfate versus conventional processing which involves either roasting of the ore for Cu recovery or leaching of the ore for several days.

Extraction of hydrothermal alterations from ASTER SWIR data from east Zanjan, northern Iran

NASA Astrophysics Data System (ADS)

Azizi, H.; Tarverdi, M. A.; Akbarpour, A.

2010-07-01

The use of satellite images for mineral exploration has been very successful in pointing out the presence of minerals such as smectite and kaolinite which are important in the identification of hydrothermal alterations. Shortwave infrared (SWIR) bands from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with the wavelength of ASTER SWIR bands between 1.65 and 2.43 μm has a good potential for mapping a hydrothermal alteration minerals such as alunite, pyrophyllite, kaolinite, illite-muscovite-sericite, and carbonate. In this range, hydroxide minerals which have been produced by hydrothermal alteration exhibit good absorption compared to shorter or longer wavelengths. In this research which aims to remove atmospheric and topographic effects from ASTER SWIR data, the authors used the log-residual method (LRM) with the minimum noise fraction (MNF) transformation to create a pixel purity index (PPI) which was used to extract the most spectrally pure pixels from multispectral images. Spectral analyses of the clay mineralogy of the study area (east Zanjan, in northern Iran) were obtained by matching the unknown spectra of the purest pixels to the U.S. Geological Survey (USGS) mineral library. Three methods, spectral feature fitting (SFF), spectral angle mapping (SAM), and binary encoding (BE) were used to generate a score between 0 and 1, where a value of 1 indicates a perfect match showing the exact mineral type. In this way, it was possible to identify certain mineral classes, including chlorite, carbonate, calcite-dolomite-magnesite, kaolinite-smectite, alunite, and illite. In this research, two main propylitic and phyllic-argillic zones could be separated using their compositions of these minerals. These two alteration zones are important for porphyry copper deposits and gold mineralization in this part of Iran.

Mapping Weathering and Alteration Minerals in the Comstock and Geiger Grade Areas using Visible to Thermal Infrared Airborne Remote Sensing Data

NASA Technical Reports Server (NTRS)

Vaughan, Greg R.; Calvin, Wendy M.

2005-01-01

To support research into both precious metal exploration and environmental site characterization a combination of high spatial/spectral resolution airborne visible, near infrared, short wave infrared (VNIR/SWIR) and thermal infrared (TIR) image data were acquired to remotely map hydrothermal alteration minerals around the Geiger Grade and Comstock alteration regions, and map the mineral by-products of weathered mine dumps in Virginia City. Remote sensing data from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), SpecTIR Corporation's airborne hyperspectral imager (HyperSpecTIR), the MODIS-ASTER airborne simulator (MASTER), and the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) were acquired and processed into mineral maps based on the unique spectral signatures of image pixels. VNIR/SWIR and TIR field spectrometer data were collected for both calibration and validation of the remote data sets, and field sampling, laboratory spectral analyses and XRD analyses were made to corroborate the surface mineralogy identified by spectroscopy. The resulting mineral maps show the spatial distribution of several important alteration minerals around each study area including alunite, quartz, pyrophyllite, kaolinite, montmorillonite/muscovite, and chlorite. In the Comstock region the mineral maps show acid-sulfate alteration, widespread propylitic alteration and extensive faulting that offsets the acid-sulfate areas, in contrast to the larger, dominantly acid-sulfate alteration exposed along Geiger Grade. Also, different mineral zones within the intense acid-sulfate areas were mapped. In the Virginia City historic mining district the important weathering minerals mapped include hematite, goethite, jarosite and hydrous sulfate minerals (hexahydrite, alunogen and gypsum) located on mine dumps. Sulfate minerals indicate acidic water forming in the mine dump environment. While there is not an immediate threat to the community, there are clearly sources of acidic drainage that were identified remotely.

Field Integration of Worldview-3 as new Frontier of Mineral Exploration for Tropical Zone

NASA Astrophysics Data System (ADS)

Mahanta, P.; Maiti, S.

2017-12-01

Worldview-3 (WV-3) is a newly launched satellite program (2014) with total of 8 VNIR bands and 8 SWIR bands covering all possible absorption features of alteration minerals. Therefore integration of WV-3 dataset with conventional geological studies can be new frontier for mineral exploration. In the present study, we successfully accomplished that by identifying alteration mineral assemblage, field investigation, XRD, XRF and microscopic study etc. The chosen study area SPSZ, 120km long and 4-5km width corridor of highly sheared and deformed rock masses is unexplored in comparison to adjacent Singhbhum Shear Zone (SSZ). It demarcates the boundary between Proterozoic Chottanagpur Granite Gneissic Complex (CGGC) in north and Paleo proterozoic North Singhbhum Mobile belt (NSMB) in south. Discrete local studies indicated the presence of U, REE, Clay, Fe & Mn along with some Au and other polymetallic deposits of low concentration. Earlier attempts of remote sensing studies were hindered due to coarse spatial resolution, similarity between spectra of vegetation and alteration group of minerals like clay and mica, and lack of ground truthing with field spectra and laboratory analysis. Here involving WV-3, we identified and mapped alteration minerals kaolinite, montmorillonite, pyrophyllite, white mica, sericite, goethite, lemonite, hematite and quartz with better resolution and accuracy (78%). Further, field spectra and XRD analyses supports these results and confirm the presence of alterations. XRF analysis identified the presence of Cu (0.06±0.03), Ti (1.7±1), and V (0.03±0.02) anomaly pointing towards possible mineralization. Occurrences of alteration as vertically dipping and alternating with iron (red and black) and mica rich (white and gray) zones in hills as well as microscopic evidences of chloritization and sericitization of feldspars were collectively pointing towards their hydrothermal origin. Finally, we conclude that WV-3 will add a new direction to mineral exploration, as it have the potential to map complex alteration pattern with small spatial occurrence and frequent variation of individual more precisely even for vegetated and unexplored vicinity.

Aluminium X-ray absorption Near Edge Structure in model compounds and Earth's surface minerals

NASA Astrophysics Data System (ADS)

Ildefonse, P.; Cabaret, D.; Sainctavit, P.; Calas, G.; Flank, A.-M.; Lagarde, P.

Aluminium K-edge X-ray absorption near edge spectra (XANES) of a suite of silicate and oxides minerals consist of electronic excitations occurring in the edge region, and multiple scattering resonances at higher energies. The main XANES feature for four-fold Al is at around 2 eV lower energy than the main XANES feature for six-fold Al. This provides a useful probe for coordination numbers in clay minerals, gels, glasses or material with unknown Al-coordination number. Six-fold aluminium yields a large variety of XANES features which can be correlated with octahedral point symmetry, number of aluminium sites and distribution of Al-O distances. These three parameters may act together, and the quantitative interpretation of XANES spectra is difficult. For a low point symmetry (1), variations are mainly related to the number of Al sites and distribution of Al-O distances: pyrophyllite, one Al site, is clearly distinguished from kaolinite and gibbsite presenting two Al sites. For a given number of Al-site (1), variations are controlled by changes in point symmetry, the number of XANES features being increased as point symmetry decreases. For a given point symmetry (1) and a given number of Al site (1), variations are related to second nearest neighbours (gibbsite versus kaolinite). The amplitude of the XANES feature at about 1566 eV is a useful probe for the assessment of AlIV/Altotal ratios in 2/1 phyllosilicates. Al-K XANES has been performed on synthetic Al-bearing goethites which cannot be studied by 27Al NMR. At low Al content, Al-K XANES is very different from that of α-AlOOH but at the highest level, XANES spectrum tends to that of diaspore. Al-K XAS is thus a promising tool for the structural study of poorly ordered materials such as clay minerals and natural alumino-silicate gels together with Al-subsituted Fe-oxyhydroxides.

Origin, distribution, and rapid removal of hydrothermally formed clay at Mount Baker, Washington

USGS Publications Warehouse

Frank, David

1983-01-01

Clay minerals are locally abundant in two hydrothermal areas at Mount Baker-Sherman Crater and the Dorr Fumarole Field. The silt- and clay-size fractions of volcanic debris that is undergoing alteration at and near the ground surface around areas of current fumarolic activity in Sherman Crater are largely dominated by alunite and a silica phase, either opal or cristobalite, but contain some kaolinite and smectite. Correspondingly, the chemistry of solutions at the surface of the crater, as represented by the crater lake, favors the formation of alunite over kaolinite. In contrast, vent-filling debris that was ejected to the surface from fumaroles in 1975 contains more than 20 percent clay-size material in which kaolinite and smectite are dominant. The youngest eruptive deposit (probably 19th century) on the crater rim was also altered prior to ejection and contains as much as 27 percent clay-size material in which kaolinite, smectite, pyrophyllite, and mixed-layer illitesmectite are abundant. The hydrothermal products, kaolinite and alunite, are present in significant amounts in five large Holocene mudflows that originated at the upper cone of Mount Baker. The distribution of kaolinite in crater and valley deposits indicates that, with the passage of time, increasingly greater amounts of this clay mineral have been incorporated into large mass movements from the upper cone. Either erosion has cut into more kaolinitic parts of the core of Sherman Crater, or the amount of kaolinite has increased through time in Sherman Crater.

Experimental measurements of the Hugoniot of stishovite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furnish, M.D.; Ito, Eichi

1995-10-01

The crust and mantle of the Earth are primarily composed of silicates. The properties of these materials under compression are of interest for deducing deep-earth composition. As well, the properties of these materials under shock compression are of interest for calculating groundshock propagation. The authors have synthesized, characterized, and performed Hugoniot measurements on monolithic polycrystalline SiO{sub 2} samples which were predominantly stishovite (a high-pressure polymorph). Synthesis was accomplished in a multianvil press with pyrophyllite gaskets and carbon heaters. The samples had densities ranging from 3.80 to 4.07, corresponding to stishovite volume fractions of 0.7 to 0.87, a range confirmed bymore » NMR analysis. Electron microprobe and X-ray fluorescence characterizations showed minor carbon contamination (< 1%), with no other significant impurities. Samples {approximately} 1 mm thick and 3 mm diameter were tested in reverse and forward-ballistics modes on a two-stage light gas gun, using velocity interferometry diagnostics. Impact velocities ranged from 4.0 to 6.5 km/sec. Hugoniot stresses for four tests ranged from 65 to 225 GPa. At higher stresses significant uncertainties arise due to impact tilt/nonplanarity issues. Results are consistent with earlier predictions of the stishovite Hugoniot based on quartz-centered Hugoniot data, static-compression (diamond-anvil cell) data and hydrostatic multianvil cell data. Release behavior appears to be frozen. These results are remarkable in view of the small size of the samples used. Results are compared with current EOS models.« less

Dehydration reactions, mass transfer and rock deformation relationships during subduction of Alpine metabauxites: insights from LIBS compositional profiles between metamorphic veins

NASA Astrophysics Data System (ADS)

Verlaguet, A.; Brunet, F.; Goffe, B.; Menut, D.; Findling, N.; Poinssot, C.

2011-12-01

In subduction zones, the significant amounts of aqueous fluid released in the course of the successive dehydration reactions occurring during prograde metamorphism are expected to strongly influence the rock rheology, as well as kinetics of metamorphic reactions and mass transfer efficiency. Mineralized veins, ubiquitous in metamorphic rocks, can be seen as preserved witnesses of fluid and mass redistribution that partly accommodate the rock deformation (lateral segregation). However, the driving forces and mechanisms of mass transfer towards fluid-filled open spaces remain somewhat unclear. The aim of this study is to investigate the modalities of mass transfer during local fluid-rock interactions, and their links with fluid production and rock deformation. This study focuses on karstic pockets (metre scale) of Triassic metabauxites embedded in thick carbonate units, that have been isolated from large-scale fluid flow during HP-LT Alpine metamorphism (W. Vanoise, French Alps). These rocks display several generations of metamorphic veins containing various Al-bearing minerals, which give particular insights into mass transfer processes. It is proposed that the internally-derived fluid (~13 vol% produced by successive dehydration reactions) has promoted the opening of fluid-filled open spaces (euhedral habits of vein minerals) and served as medium for diffusive mass transfer from rock to vein. Based on mineralogical and textural features, two vein types can be distinguished: (1) some veins are filled with newly formed products of either prograde (chloritoid) or retrograde (chlorite) metamorphic reactions; in this case, fluid-filled open spaces seem to offer energetically favourable nucleation/growth sites; (2) the second vein type is filled with cookeite (Li-Al-rich chlorite) or pyrophyllite, that were present in the host rock prior to the vein formation. In this closed chemical system, mass transfer from rock to vein was achieved through the fluid, in a dissolution-transport-precipitation process, possibly stress-assisted. Cookeite is highly concentrated (40-70 vol%) in regularly spaced veins. Laser Induced Breakdown Spectroscopy profiles show that cookeite is evenly distributed in the rock matrix comprised between two veins. The absence of diffusion profiles suggests that the characteristic diffusion length for Li, Al and Si is greater than or equal to the distance separating two cookeite veins (3-6 cm). This is in agreement with characteristic diffusion lengths calculated from both grain boundary and pore fluid diffusion coefficients, for the estimated duration of the peak of metamorphism. Phyllosilicates have very different morphologies in the rock matrix (fibers) compared to veins (euhedral crystals): fluid-mineral interfacial energy may be maximal in the small matrix pores, which can maintain higher cookeite solubility than in fluid-filled open spaces. Therefore, as soon as veins open, chemical potential gradients may develop and drive cookeite transfer from rock matrix to veins.

Genesis of the Permian karstic Pingguo bauxite deposit, western Guangxi, China

NASA Astrophysics Data System (ADS)

Liu, Xuefei; Wang, Qingfei; Zhang, Qizuan; Yang, Shujuan; Liang, Yayun; Zhang, Ying; Li, Yan; Guan, Tao

2017-10-01

More than 0.5 billion tons of late Permian bauxite overlies the karstic topography of the Maokou Formation of western Guangxi in China. Here, we provide new mineralogical, geochemical, Sr-Nd-Pb isotopic, and pyrite S isotope and trace element compositional data for the Pingguo bauxite deposit, aiming to further our understanding of the genesis of Permian bauxite. The Pingguo bauxite contains three distinct layers: a lower layer dominated by ferric clay or weathered iron ore, a middle layer of cryptocrystalline and oolitic bauxite ore, and an upper layer dominated by argillaceous bauxite. The bauxite ore is mainly diaspore, pyrite, chamosite, and anatase, whereas the argillaceous bauxite contains diaspore, kaolinite, pyrophyllite, pyrite, and anatase. Two types of pyrite have been identified within the bauxite: fine-grained and framboidal pyrite (Py1) occurring in aggregates and coarse-grained and euhedral pyrite (Py2). Py1 is enriched in trace elements and is thought to have a diagenetic origin, whereas Py2 is deficient in trace elements and is considered to have formed by later recrystallization. The S isotopic composition of pyrite (-34.11 to -18.91‰) and visible ovoid microorganisms within the bauxite provide evidences of microbial activity during bauxite formation. The Sr-Nd-Pb isotopic composition of the bauxite indicates that these ores were generated by the weathering of basalts belonging to the Emeishan Large Igneous Province (LIP) and limestones of the Maokou Formation. Microorganisms were likely to have enhanced the dissolution and weathering of the parent rock and facilitated the precipitation of diaspore under near-surface conditions.

The Effect of Fracture Filler Composition on the Parameters of Shear Deformation Regime

NASA Astrophysics Data System (ADS)

Pavlov, D.; Ostapchuk, A.; Batuhtin, I.

2015-12-01

Geomechanical models of different slip mode nucleation and transformation can be developed basing on laboratory experiments, in which regularities of shear deformation of gouge-filled faults are studied. It's known that the spectrum of possible slip modes is defined by both macroscopic deformation characteristics of the fault and mesoscale structure of fault filler. Small variations of structural parameters of the filler may lead to a radical change of slip mode [1, 2]. This study presents results of laboratory experiments investigating regularities of shear deformation of discontinuities filled with multicomponent granular material. Qualitative correspondence between experimental results and natural phenomena is detected. The experiments were carried out in the classical "slider model" statement. A granite block slides under shear load on a granite substrate. The contact gap between rough surfaces was filled with a discrete material, which simulated the principal slip zone of a fault. The filler components were quartz sand, salt, glass beads, granite crumb, corundum, clay and pyrophyllite. An entire spectrum of possible slip modes was obtained - from stable slip to slow-slip events and to regular stick-slip with various coseismic displacements realized per one act of instability. Mixing several components in different proportions, it became possible to trace the gradual transition from stable slip to regular stick-slip, from slow-slip events to fast-slip events. Depending on specific filler component content, increasing the portion of one of the components may lead to both a linear and a non-linear change of slip event moment (a laboratory equivalent of the seismic moment). For different filler compositions durations of equal-moment events may differ by more than two orders of magnitude. The findings can be very useful for developing geomechnical models of nucleation and transformation of different slip modes observed at natural faults. The work was supported by RFBR (grant no. 13-05-00780). 1. Mair, K., K. M. Frye, and C. Marone (2002), J.Geophys.Res., 107(B10), 2219. 2. G.G. Kocharyan, V.K. Markov, A.A. Ostapchuk, and D.V. Pavlov (2014), Phys.Mes, 17(2), 123-133.

In Situ Optical Observation of High-Temperature Geological Processes With the Moissanite Cell

NASA Astrophysics Data System (ADS)

Walte, N.; Keppler, H.

2005-12-01

A major drawback of existing techniques in experimental earth and material sciences is the inability to observe ongoing high-temperature processes in situ during an experiment. Examples for important time-dependent processes include the textural development of rocks and oxide systems during melting and crystallization, solid-state and melt-present recrystallization and Ostwald ripening, and bubble nucleation and growth during degassing of glasses and melts. The investigation of these processes by post-mortem analysis of a quenched microstructure is time consuming and often unsatisfactory. Here, we introduce the moissanite cell that allows optical in situ observation of long-term experiments at high temperatures. Moissanite is a transparent gem-quality type of SiC that is characterized by its hardness and superior chemical and thermal resistance. Two moissanite windows with a thickness and diameter of several millimeters are placed into sockets of fired pyrophyllite and fixed onto two opposite metal plates. The sockets are wrapped with heating wire and each window is connected to a thermocouple for temperature control. The sample is placed directly between the moissanite windows and the cell is assembled similarly to a large diamond anvil cell. In situ observation of the sample is done with a microscope through observation windows and movies are recorded with an attached digital camera. Our experiments with the new cell show that temperatures above 1200°C can be maintained and observed in a sample for several days without damaging the cell nor the windows. Time-lapse movies of melting and crystallizing natural and synthetic rocks and of degassing glasses and melts will be presented to show the potential of the new technique for experimental earth and material science.

Lake Erie walleyes--again on the upswing?

USGS Publications Warehouse

Seldon, Charles P.; Van Meter, Harry D.

1960-01-01

SUMMARY The effect of DDT dust on wildlife was studied at Camp Bullis, Bexar County, Texas, in the summer of 1947. Studies were made on a 206.6 acre plot that was treated with DDT for experimental control of the Lone Star tick (Amblyomrna americanum). A dust consisting of one part of DDT to nine parts of pyrophyllite was applied at an average rate of 4.4 pounds of DDT per acre. The limits of DDT concentration that affected wildlife cannot be stated exactly because of a heavy rain that fell near the end of the dusting, and because of irregularity in DDT deposition. Since absolute uniformity of dusting could not be expected in any large scale DDT application, the effects observed in these trials were probably fairly representative. However, continued dry weather would have permitted longer exposure to DDT, possibly with more severe effects than those found in this study. The vegetation of the experimental area was roughly 70 percent ungrazed tall-grass prairie and 30 percent trees and shrubs. Ground and bush feeding birds were severely affected. Cardinals, lark sparrows, field sparrows, Bewick's wrens, Carolina wrens, Kentucky warblers, yellow-breasted chats, blue grosbeaks, and painted buntings were nearly or entirely eliminated from the treated area. Birds affected, but less drastically reduced in numbers, were yellow-billed cuckoo, black and white warbler, yellow-throated vireo, and white-eyed vireo. Birds found dead in the DDT area were 9 cardinals, 2 painted buntings, 2 lark sparrows, 1 yellow-breasted chat, and 1 white-eyed vireo. Bird mortality had begun by the day after dusting and was largely over by the end of the fifth day. Census of deer in DDT and check areas before and after treatment showed no reduction in deer numbers and no diminution in use of the DDT area. No deer or fawns were found dead or affected. Box-trapping of raccoons in DDT and check areas before and after treatment showed no effects that could be attributed to DDT. Limited observations on armadillos, striped skunks, and rabbits gave no indication of pronounced damage to these forms. No mammals of any kind were found dead or affected in or near the DDT area. Four rough green snakes and one Texan spiny lizard were found dead in the DDT area. Mortality was probably high among insectivorous reptiles.

Wildlife effects of DDT dust used for tick control on a Texas prairie

USGS Publications Warehouse

George, J.L.; Stickel, W.H.

1949-01-01

SUMMARY The effect of DDT dust on wildlife was studied at Camp Bullis, Bexar County, Texas, in the summer of 1947. Studies were made on a 206.6 acre plot that was treated with DDT for experimental control of the Lone Star tick (Amblyomrna americanum). A dust consisting of one part of DDT to nine parts of pyrophyllite was applied at an average rate of 4.4 pounds of DDT per acre. The limits of DDT concentration that affected wildlife cannot be stated exactly because of a heavy rain that fell near the end of the dusting, and because of irregularity in DDT deposition. Since absolute uniformity of dusting could not be expected in any large scale DDT application, the effects observed in these trials were probably fairly representative. However, continued dry weather would have permitted longer exposure to DDT, possibly with more severe effects than those found in this study. The vegetation of the experimental area was roughly 70 percent ungrazed tall-grass prairie and 30 percent trees and shrubs. Ground and bush feeding birds were severely affected. Cardinals, lark sparrows, field sparrows, Bewick's wrens, Carolina wrens, Kentucky warblers, yellow-breasted chats, blue grosbeaks, and painted buntings were nearly or entirely eliminated from the treated area. Birds affected, but less drastically reduced in numbers, were yellow-billed cuckoo, black and white warbler, yellow-throated vireo, and white-eyed vireo. Birds found dead in the DDT area were 9 cardinals, 2 painted buntings, 2 lark sparrows, 1 yellow-breasted chat, and 1 white-eyed vireo. Bird mortality had begun by the day after dusting and was largely over by the end of the fifth day. Census of deer in DDT and check areas before and after treatment showed no reduction in deer numbers and no diminution in use of the DDT area. No deer or fawns were found dead or affected. Box-trapping of raccoons in DDT and check areas before and after treatment showed no effects that could be attributed to DDT. Limited observations on armadillos, striped skunks, and rabbits gave no indication of pronounced damage to these forms. No mammals of any kind were found dead or affected in or near the DDT area. Four rough green snakes and one Texan spiny lizard were found dead in the DDT area. Mortality was probably high among insectivorous reptiles.

Adsorption of nucleotides onto ferromagnesian phyllosilicates: Significance for the origin of life

NASA Astrophysics Data System (ADS)

Pedreira-Segade, Ulysse; Feuillie, Cécile; Pelletier, Manuel; Michot, Laurent J.; Daniel, Isabelle

2016-03-01

The concentration of prebiotic organic building blocks may have promoted the formation of biopolymers in the environment of the early Earth. We therefore studied the adsorption of RNA monomers AMP, GMP, CMP, and UMP, and DNA monomers dGMP, dCMP, and TMP, on minerals that were abundant in the early Earth environment as the result of aqueous or hydrothermal alteration of the primitive oceanic crust. We focused our study on swelling clays, i.e. nontronite and montmorillonite, and non-swelling phyllosilicates, i.e. pyrophyllite, chlorite, lizardite and chrysotile suspended in an aqueous saline solution analog to seawater. In this reference study, adsorption experiments were carried out under standard conditions of pressure and temperature and controlled pH. Under such conditions, this work is also relevant to the preservation of nucleic acids in Fe-Mg-rich terrestrial and Martian soils. We compared the adsorption of the different monomers on individual minerals, as well as the adsorption of single monomers on the whole suite of minerals. We found that DNA monomers adsorb much more strongly than RNA monomers, and that any monomer containing the G nucleobase adsorbed more strongly than one containing the C nucleobase. At high surface loadings (greater than about 1 mM monomer in aqueous solution) we also found a dramatic increase in the slope of adsorption isotherm on the swelling clays, leading to large increases in the amounts adsorbed. Data were processed in order to understand the adsorption mechanism of nucleotides onto mineral surfaces. We infer that all nucleotides behave as homologous molecules in regard to their adsorption onto the studied mineral surfaces. At low to moderate surface loadings, their adsorption is best explained by a single mechanism common to the suite of minerals of the present study. At pH 7, adsorption certainly proceeds by ligand exchange between the phosphate group and the hydroxyls of the broken edges of phyllosilicates leading to the saturation of lateral surfaces. Below pH 4, swelling clays also adsorb nucleotides through cation exchange on basal surfaces, whereas non-swelling phyllosilicates do not. However, at high surface loadings an additional mechanism stabilizing adsorption occurs. Given the proposed adsorption mechanisms, the possibility of a favorable polymerization at the mineral-water interface is discussed. We propose that Fe-Mg rich phyllosilicates tightly bind nucleotides, under ambient conditions, and concentrate them up to 1000 times the solution concentration upon saturation. Nontronites have the most diverse and favorable adsorption behaviors and could have helped to the concentration and polymerization of nucleotides under primitive Earth-like conditions.

Dehydration reactions, mass transfer and rock deformation relationships during subduction of Alpine metabauxites: insights from LIBS compositional profiles between metamorphic veins

NASA Astrophysics Data System (ADS)

Verlaguet, Anne; Brunet, Fabrice; Goffé, Bruno; Menut, Denis; Findling, Nathaniel; Poinssot, Christophe

2013-04-01

In subduction zones, the significant amounts of aqueous fluid released in the course of the successive dehydration reactions occurring during prograde metamorphism are expected to strongly influence the rock rheology, as well as kinetics of metamorphic reactions and mass transfer efficiency. Mineralized veins, ubiquitous in metamorphic rocks, can be seen as preserved witnesses of fluid and mass redistribution that partly accommodate the rock deformation (lateral segregation). However, the driving forces and mechanisms of mass transfer towards fluid-filled open spaces remain somewhat unclear. The aim of this study is to investigate the vein-forming processes and the modalities of mass transfer during local fluid-rock interactions, and their links with fluid production and rock deformation, with new insights from Laser Induced Breakdown Spectroscopy (LIBS) profiles. This study focuses on karstic pockets (metre scale) of Triassic metabauxites embedded in thick carbonate units, that have been isolated from large-scale fluid flow during HP-LT Alpine metamorphism (W. Vanoise, French Alps). These rocks display several generations of metamorphic veins containing various Al-bearing minerals, which give particular insights into mass transfer processes. It is proposed that the internally-derived fluid (~13 vol% produced by successive dehydration reactions) has promoted the opening of fluid-filled open spaces (euhedral habits of vein minerals) and served as medium for diffusive mass transfer from rock to vein. Based on mineralogical and textural features, two vein types can be distinguished: (1) some veins are filled with newly formed products of either prograde (chloritoid) or retrograde (chlorite) metamorphic reactions; in this case, fluid-filled open spaces seem to offer energetically favourable nucleation/growth sites; (2) the second vein type is filled with cookeite (Li-Al-rich chlorite) or pyrophyllite, that were present in the host rock prior to the vein formation. In this closed chemical system, mass transfer from rock to vein was achieved through the fluid, in a dissolution-transport-precipitation process, possibly stress-assisted. To investigate the modalities of mass transfer towards this second vein type, LIBS profiles were performed in the rock matrix, taking Li concentration as a proxy for cookeite distribution. Cookeite is highly concentrated (40-70 vol%) in regularly spaced veins, and the LIBS profiles show that cookeite is evenly distributed in the rock matrix comprised between two veins. The absence of diffusion profiles suggests that the characteristic diffusion length for Li, Al and Si is greater than or equal to the distance separating two cookeite veins (3-6 cm). This is in agreement with characteristic diffusion lengths calculated from both grain boundary and pore fluid diffusion coefficients, for the estimated duration of the peak of metamorphism. Concerning mass transfer driving forces, phyllosilicates have very different morphologies in the rock matrix (fibers) compared to veins (euhedral crystals): fluid-mineral interfacial energy may be maximal in the small matrix pores, which can maintain higher cookeite solubility than in fluid-filled open spaces. Therefore, as soon as veins open, chemical potential gradients may develop and drive cookeite transfer from rock matrix to veins.

The Totumo mud volcano and its near-shore marine sedimentological setting (North Colombia) - From sedimentary volcanism to epithermal mineralization

NASA Astrophysics Data System (ADS)

Dill, H. G.; Kaufhold, S.

2018-04-01

The Holocene mud volcano exposed at Totumo (younger than 4150 ± 50 yr BP) lines up together with some other landforms of its kind along the Caribbean Coast in northern Colombia. It currently vents a mud of the silicate-phosphate-bearing sulfur-sodium chloride type. The mud volcanoes evolved in an active continental margin setting of the South American Cordillera with high seismicity and affected by pervasive neotectonic structural disturbances. During the Neogene and Quaternary linear terrigenous shoreline sediments alternating with delta deposits evolved on this mobile crustal segment between the Andes and ancient Precambrian cratons. Meso- to microtidal sedimentary settings during transgression and progradation created meta- to instable sedimentary and petrophysical conditions (e.g. overpressure and gas-bearing bubble sands), favorable for the formation of mud volcanoes, whose lithofacies is subdivided into (1) footwall facies (detritus from metabasic, -pelitic source rocks), (2) mud volcano plus lateral facies (material from deep-seated hydrothermal sources, hydrocarbon plays, and brine reflux from the sea), (3) hanging wall facies, sand characterized by a strong longshore drift. The sedimentary volcanism in the area is characterized by different temperatures of formation: (1) pre-stage (<100 °C) and (2) recent stage (≈25 °C). Heavy (pyroxene, amphibole, epidote-clinozoisite, Fe-Ti silicates and oxides, garnet, alumosilicates, tourmaline, zircon, barite, Fe sulfides and -sulfates), light (Ca sulfates, calcite, quartz, feldspar) and clay minerals (kaolinite, mica, pyrophyllite, chlorite, vermiculite) are efficient tools to determine the source of mud, to subdivide the mud volcano system as to its facies and describe its physical-chemical regime as to the temperature of formation, pH and Eh values. The mud volcano system of Totumo bridges the gap between sedimentary "volcanism" and epithermal hot spring deposits of intermediate to high sulfidation and forms a useful "guide" to hydrocarbon accumulation.

Process for converting sodium nitrate-containing, caustic liquid radioactive wastes to solid insoluble products

DOEpatents

Barney, Gary S.; Brownell, Lloyd E.

1977-01-01

A method for converting sodium nitrate-containing, caustic, radioactive wastes to a solid, relatively insoluble, thermally stable form is provided and comprises the steps of reacting powdered aluminum silicate clay, e.g., kaolin, bentonite, dickite, halloysite, pyrophyllite, etc., with the sodium nitrate-containing radioactive wastes which have a caustic concentration of about 3 to 7 M at a temperature of 30.degree. C to 100.degree. C to thereby entrap the dissolved radioactive salts in the aluminosilicate matrix. In one embodiment the sodium nitrate-containing, caustic, radioactive liquid waste, such as neutralized Purex-type waste, or salts or oxide produced by evaporation or calcination of these liquid wastes (e.g., anhydrous salt cake) is converted at a temperature within the range of 30.degree. C to 100.degree. C to the solid mineral form-cancrinite having an approximate chemical formula 2(NaAlSiO.sub.4) .sup.. xSalt.sup.. y H.sub.2 O with x = 0.52 and y = 0.68 when the entrapped salt is NaNO.sub.3. In another embodiment the sodium nitrate-containing, caustic, radioactive liquid is reacted with the powdered aluminum silicate clay at a temperature within the range of 30.degree. C to 100.degree. C, the resulting reaction product is air dried eitheras loose powder or molded shapes (e.g., bricks) and then fired at a temperature of at least 600.degree. C to form the solid mineral form-nepheline which has the approximate chemical formula of NaAlSiO.sub.4. The leach rate of the entrapped radioactive salts with distilled water is reduced essentially to that of the aluminosilicate lattice which is very low, e.g., in the range of 10.sup.-.sup.2 to 10.sup.-.sup.4 g/cm.sup.2 -- day for cancrinite and 10.sup.-.sup.3 to 10.sup.-.sup.5 g/cm.sup.2 -- day for nepheline.

Helium isotope data from the Goldfield epithermal system, Nevada: Evidence for volatile input from a primitive mantle source during ore formation

NASA Astrophysics Data System (ADS)

Hofstra, A. H.; Manning, A. H.

2013-12-01

Goldfield is the largest high sulfidation epithermal gold mining district in the United States with over 130 t of gold production and 23 sq. km. of argillic alteration (with alunite, pyrophyllite, or kaolinite). It formed at 20.0×0.5 Ma in an andesite to rhyolite volcanic field in the ancestral Cascades continental magmatic arc. Previous stable isotope studies of quartz, alunite, and sulfide minerals suggest that the gold ores formed in a magmatic vapor plume derived from a subjacent porphyry intrusion, which displaced and mixed with meteoric groundwater at shallow levels. The isotopic compositions of He, Ne, and Ar trapped in fluid inclusions in hydrothermal minerals (Cu-sulfides and sulfosalts, pyrite, quartz) were measured to further constrain volatile source and migration processes. Gases were released by thermal decrepitation at 300°C and analyzed using a high resolution static sector mass spectrometer. The isotopic compositions of Ne and Ar are typical of air-saturated water (ASW), indicating that the samples contain little nucleogenic Ne or radiogenic Ar derived from underlying old crustal sources. In contrast, He/Ne and He/Ar ratios are much greater than ASW, indicating that a component of He was produced in the subsurface. The wide range of He R/Ra values, 0.4 to 20, suggests that He was derived from both crustal and mantle sources. 4He/40Ar* and 4He/21Ne* systematics are characteristic of magma degassing. The highest R/Ra values (15-20) are well above those previously reported for modern volcanic rocks and geothermal fluids in subduction-related arcs. Such R/Ra values indicate a primitive mantle source, perhaps below the subducting slab. We hypothesize that the discharge of metal-laden fluids from the subjacent porphyry intrusion was influenced by the input of hot volatiles from mafic mantle-derived magmas. This scenario implies a magma column that remained open to the flux of volatiles over a considerable depth range, from the mantle to the shallow crust. This exceptional volatile plumbing system may be an important ingredient in the formation of large, high sulfidation gold deposits. The ascent of mantle-sourced volatiles may be related to the coeval transition from transpression to transtension within the western North American plate caused by microplate capture along the San Andreas transform.

Geoinformatics and Data Fusion in the Southwestern Utah Mineral Belt

NASA Astrophysics Data System (ADS)

Kiesel, T.; Enright, R.

2012-12-01

Data Fusion is a technique in remote sensing that combines separate geophysical data sets from different platforms to yield the maximum information of each set. Data fusion was employed on multiple sources of data for the purposes of investigating an area of the Utah Mineral Belt known as the San Francisco Mining District. In the past many mineral deposits were expressed in or on the immediate surface and therefore relatively easy to locate. More modern methods of investigation look for evidence beyond the visible spectrum to find patterns that predict the presence of deeply buried mineral deposits. The methods used in this study employed measurements of reflectivity or emissivity features in the infrared portion of the electromagnetic spectrum for different materials, elevation data collected from the Shuttle Radar Topography Mission and indirect measurement of the magnetic or mass properties of deposits. The measurements were collected by various spaceborne remote sensing instruments like Landsat TM, ASTER and Hyperion and ground-based statewide geophysical surveys. ASTER's shortwave infrared bands, that have been calibrated to surface reflectance using the atmospheric correction tool FLAASH, can be used to identify products of hydrothermal alteration like kaolinite, alunite, limonite and pyrophyllite using image spectroscopy. The thermal infrared bands once calibrated to emissivity can be used to differentiate between felsic, mafic and carbonate rock units for the purposes of lithologic mapping. To validate results from the extracted spectral profiles existing geological reports were used for ground truth data. Measurements of electromagnetic spectra can only reveal the composition of surface features. Gravimetric and magnetic information were utilized to reveal subsurface features. Using Bouguer anomaly data provided by the USGS an interpreted geological cross section can be created that indicates the shape of local igneous intrusions and the depth of sedimentary basins. By comparing the digital elevation model with a satellite photo of the area a major high angle fault system was identified that had not been clearly evaluated in previous geologic mapping. For the investigation of the Frisco Mining District, gravity and magnetic data was fused to help differentiate igneous and sedimentary rocks that might have the same density. Data fusion allows for a more thorough analysis rather than viewing each data set separately with the accompanying improvement in ability to understand the complex geology of an area and can be applied to any remote sensing data set regardless of the type of instrument used.

Restoration of Late Neoarchean-Early Cambrian tectonics in the Rengali orogen and its environs (eastern India): The Antarctic connection

NASA Astrophysics Data System (ADS)

Bhattacharya, A.; Das, H. H.; Bell, Elizabeth; Bhattacharya, Atreyee; Chatterjee, N.; Saha, L.; Dutt, A.

2016-10-01

Geological mapping and P-T path reconstructions are combined with monazite chemical age and Secondary Ion Mass Spectrometric (SIMS) U-Pb zircon age determinations to identify crustal domains with distinctive evolutionary histories in the Rengali orogen sandwiched between two Grenvillian-age metamorphic belts, i.e. the Eastern Ghats Granulite Belt (EGGB) in the south, and the amphibolite facies Gangpur Schist Belt (GSB) in the north, which in turn forms a collar along the NW/W margins of the Paleo/Mesoarchean Singhbhum Craton (SC) north of the Rengali orogen. Anatectic gneisses in the orogen core exhibit multi-phase Neoarchean/Paleoproterozoic deformation, metamorphic P-T histories and juvenile magma emplacement events. The high-grade belt is inferred to be a septum of the Bastar Craton (BC). The flanking supracrustal belt in the orogen - dominated by quartz-muscovite schists (± staurolite, kyanite, garnet pyrophyllite), inter-bedded with poorly-sorted and polymict meta-conglomerate, and meta-ultramafic/amphibolite bands - evolved along P-T paths characterized by sub-greenschist to amphibolite facies peak P-T conditions in closely-spaced samples. The supracrustal rocks and the anatectic gneisses of contrasting metamorphic P-T histories experienced D1, D2 and D3 fabric-forming events, but the high-angle obliquity between the steeply-plunging D3 folds in the anatectic gneisses and the gently-plunging D3 folds in the supracrustal unit suggests the two lithodemic units were tectonically accreted post-S2. The supracrustal belt is inferred to be a tectonic mélange formed in an accretionary wedge at the tri-junction of the Bastar Craton, the Eastern Ghats Granulite Belt and the Singhbhum Craton; the basin closure synchronous with the assembly of EGGB and the Singhbhum Craton-Gangpur Schist belt composite occurred between 510 and 610 Ma. Based on the available evidence across the facing coastlines of the Greater India landmass and the Australo-Antarctic blocks at 500 Ma, it is suggested that the EGGB welded with the Greater India landmass during the Pan African along an accretion zone, of which the Rengali orogen is a part, synchronous with the final assembly of the Gondwanaland.

Alteration and mineralization of an oceanic forearc and the ophiolite-ocean crust analogy

USGS Publications Warehouse

Alt, J.C.; Teagle, D.A.H.; Brewer, T.; Shanks, Wayne C.; Halliday, A.

1998-01-01

Mineralogical, chemical, and isotopic (O, C, S, and Sr) analyses were performed on minerals and bulk rocks from a forearc basement section to understand alteration processes and compare with mid-ocean ridges (MOR) and ophiolites. Ocean Drilling Program Hole 786B in the Izu-Bonin forearc penetrates 103 m of sediment and 725 m into volcanic flows, breccias, and basal dikes. The rocks comprise boninites and andesites to rhyolites. Most of the section was affected by low-temperature (<100??C) seawater alteration, with temperatures increasing downward. The rocks are partly (5-25%) altered to smectite, Fe-oxyhydroxide, calcite, and phillipsite, and exhibit gains of K, Rb, and P, loss of Ca, variable changes in Si, Na, Mg, Fe, Sr, and Y, and elevated ??18O and 87Sr/86Sr. Higher temperatures (???150??C) in the basal dikes below 750 m led to more intense alteration and formation of chlorite-smectite, corrensite, albite, K-feldspar, and quartz (??chlorite). A 5 m thick hydrothermally altered and pyritized zone at 815 m in the basal dikes reacted with mixtures of seawater and hydrothermal fluids to Mg-chlorite, albite, and pyrite, and gained Mg and S and lost Si and Ca. Focused flow of hydrothermal fluids produced sericitization halos (Na-K sericite, quartz, pyrophyllite, K-feldspar, and pyrite) along quartz veins at temperatures of 200??-250??C. High 87Sr/86Sr ratios of chloritized (???0.7055) and sericitized (???0.7065) rocks indicate involvement of seawater via mixing with hydrothermal fluids. Low ??34S of sulfide (???2 to -5.5???) and sulfate (12.5???) are consistent with input of magmatic SO2 into hydrothermal fluids and disproportionation to sulfide and sulfate. Alteration processes were generally similar to those at MORs, but the arc section is more intensively altered, in part because of the presence of abundant glassy rocks and mafic phases. The increase in alteration grade below 750 m and the mineralization in the basal dikes are analogous to changes that occur near the base of the volcanic section in MOR and the Troodos ophiolite.

The Cretaceous glauconitic sandstones of Abu Tartur, Egypt

NASA Astrophysics Data System (ADS)

Pestitschek, Brigitte; Gier, Susanne; Essa, Mahmoud; Kurzweil, Johannes

2010-05-01

The Abu Tartur mine is located in the Western Desert of Egypt, 50 km west of El Kharga City. Geologically, the Abu Tartur plateau is built by a sequence of Upper Cretaceous (Campanian - Maastrichtian) phosphorites, black shales and glauconitic sandstones. The phosphate deposits are of great economic importance and have been mined since their discovery in 1967. Outcrop sections were measured, sampled, sedimentologically characterized and described. One specific glaucony layer was investigated mineralogically and chemically in detail and compared to a subsurface sample from the mine. Two depositional regimes can be interpreted based on sedimentary architecture and structures: 1) a deeper-water hemipelagic environment, where phosphorites and organic carbon-rich shales were deposited and 2) a shallower, prograding higher energy shelf environment with glauconies. From a sequence stratigraphic perspective 1) was deposited during the transgressive systems tract and the early highstand while 2) was deposited during the remaining highstand and a lowstand prograding wedge (Glenn & Arthur, 1990). Petrographic and SEM investigations show that the glaucony grains are of authochtonous origin. XRF, EMPA and thin-section analyses show that the glaucony grains from the outcrop differ significantly in their chemical composition, morphology and color from the grains of the mine sample. The fresh glauconies are enriched in Fe2O3 and K2O compared to the surface samples. XRD analyses of the clay fraction of the six outcrop samples and the mine sample show that the grains consist of illite(glauconite)/smectite mixed-layers, with more illite layers (80 %) in the mine sample. The charge distribution diagram muscovite-pyrophyllite-celadonite shows a clear trend from smectitic glaucony to illitic glaucony, the mine sample plots exactly in the field for glauconites. All these features indicate that the surface samples are strongly altered by weathering and that glauconite progressively transforms into iron-rich illte/smectite mixed layers and then into smectites. For any chemical and mineralogical characterization of glauconites at surface, these weathering effects have to be taken into consideration. GLENN, C. R. & ARTHUR, M. A. (1990): Anatomy and origin of a Cretaceous phosphorites-greensand giant, Egypt. Sedimentology, 37, 123-154.

Volatile Evolution and Anhydrite-Bearing Dacite, Yanacocha Gold Deposit, Cajamarca, Peru: Relevance for the Sulfur Budget

NASA Astrophysics Data System (ADS)

Chambefort, I. S.; Dilles, J. H.

2006-12-01

Magmatic water, sulfur and chlorine evolved during volcanic eruptions have important climactic effects, but during passive degassing these volatiles may transport metals and produce hydrothermal ore deposits. At the Yanacocha Mine, we are examining the volatile evolution of the Miocene andesitic to dacitic volcanic rocks (ca 20 to 8 Ma). High sulfidation epithermal deposits contain >50 Moz of gold in oxides with additional deeper sulfide resources containing >5 Mt of copper. Large volumes (>10 km3) of rock are hydrothermally altered by sulfate-rich and low pH fluid to quartz, quartz-alunite, quartz-pyrophyllite, illite. Pyrite (1-5 vol.%), native sulfur, covellite, enargite and chalcopyrite constitute reduced S-species. In total, at least 500 M tonnes of sulfur were added during alteration. The San Jose ignimbrite (SJI) erupted 30 km3 magma in two cooling units at 11.50 and 11.28 Ma, and immediately predates the bulk of gold mineralization at about 10.80 Ma (Longo, 2005). This hornblende- plagioclase dacitic magma is highly oxidized with fO2 ≍ 2 NNO. Low-Al2O3 (~7 wt.%), and high- Al2O3 (~12 wt.%) amphiboles coexist in most of the samples. Plag-hbl thermobarometry on low-Al content amphibole yields ca. 1.5-2 kb and 800°C. High-Al pargasitic hornblende forms sparse crystals up to 1 cm long that often show resorption or oxide rims associated with oxyhornblende breakdown. Apatite is an inclusion but generally not plagioclase or oxide. These petrographic relations suggest that the high-Al hornblende is the liquidus phase (at 950 to 1000°C, PH2O > 3 kb) in an andesitic or basaltic magma. The high-Al amphibole in two samples contains anhydrite inclusions, one with >5 vol.% anhydrite associated with apatite having up to 1.2 wt.% SO3. Comparison of these data with experimental sulfate solubilities at NNO+2 suggests the andesitic or basaltic melt dissolved at least 1000 ppm S. One low-Al amphibole contains anhydrite, demonstrating that the cooler dacite magma was also sulfate saturated (~400 ppm S). The water content and D/H isotopic composition of amphiboles have been analyzed by TC-EA-CF mass spectrometry and by SIMS. High-Al amphiboles from three SJI samples yield δ D values of -25, -100, and -130 ‰, respectively. Partial analyses suggest that low-Al amphiboles have δ D < -100 ‰. The SJI dacitic magma chamber resided at about 4 to 8 km depth and 800C, and assimilated its hydrothermally altered roof rocks to acquire a "meteoric" δ D of -120 ‰. The dacite magma was periodically underplated or fed by hydrous (δ D = -25 ‰) sulfate-rich andesitic magma. Injection of such mafic magmas caused eruption of the two SJI sheets, but the high-Al amphiboles from the mafic magmas had a sufficiently long residence time in the dacitic magma to exchange D/H in most cases. Degassing at 10.8 Ma of about 40 km3 of dacitic magma (vapor), containing > 2000 ppm sulfate sulfur, would be needed to produce the observed hydrothermal sulfur anomaly.

Reconstruction of Ancestral Hydrothermal Systems on Mount Rainier Using Hydrothermally Altered Rocks in Holocene Debris Flows and Tephras

NASA Astrophysics Data System (ADS)

John, D. A.; Breit, G. N.; Sisson, T. W.; Vallance, J. W.; Rye, R. O.

2005-12-01

Mount Rainier is the result of episodic stages of edifice growth during periods of high eruptive activity and edifice destruction during periods of relative magmatic quiescence over the past 500 kyr. Edifice destruction occurred both by slow erosion and by catastrophic collapses, some of which were strongly influenced by hydrothermal alteration. Several large-volume Holocene debris-flow deposits contain abundant clasts of hydrothermally altered rocks, most notably the 4-km3 clay-rich Osceola Mudflow which formed by collapse of the northeast side and upper 1000+ m of the edifice about 5600 ya and flowed >120 km downstream into Puget Sound. Mineral assemblages and stable isotope data of hydrothermal alteration products in Holocene debris-flow deposits indicate formation in distinct hydrothermal environments, including magmatic-hydrothermal, steam-heated (including a large fumarolic component), magmatic steam (including a possible fumarolic component), and supergene. The Osceola Mudflow and phreatic components of coeval tephras contain the highest-temperature and inferred most deeply formed alteration minerals; assemblages include magmatic-hydrothermal quartz-alunite, quartz-topaz, quartz-pyrophyllite and quartz-illite (all +pyrite), in addition to steam-heated opal-alunite-kaolinite and abundant smectite-pyrite. In contrast, the Paradise lahar, which formed by a collapse of the surficial upper south side of the edifice, contains only steam-heated assemblages including those formed largely above the water table from condensation of fumarolic vapor (opal-alunite-jarosite). Younger debris-flow deposits on the west side of the volcano (Round Pass lahar and Electron Mudflow) contain only smectite-pyrite alteration, whereas an early 20th century rock avalanche on Tahoma Glacier also contains magmatic-hydrothermal alteration that is exposed in the avalanche headwall of Sunset Amphitheater. Mineralogy and isotopic composition of the alteration phases, geologic and geophysical data, as well as analog fossil hydrothermal systems in volcanoes elsewhere, constrain hydrothermal alteration geometry on the pre-Osceola-collapse edifice of Mount Rainier. Relatively narrow zones of acid magmatic-hydrothermal alteration in the central core of the volcano grade to more widely distributed smectite-pyrite alteration farther out on the upper flanks, capped by steam-heated alteration with a large component of alteration resulting from condensation of fumarolic vapor above the water table. Alteration was polygenetic in zones formed episodically, and was strongly controlled by fluxes of heat and magmatic fluid and by local permeability.

Novel Techniques for High Pressure Falling Sphere Viscosimetry under Simulated Earth's Mantle Conditions

NASA Astrophysics Data System (ADS)

Mueller, H. J.; Beckmann, F.; Dobson, D. P.; Hunt, S. A.; Secco, R.; Lauterjung, J.; Lathe, C.

2014-12-01

Viscosity data of melts measured under in situ high pressure conditions are crucial for the understanding of Earth's lower mantle and the interior of terrestrial and extrasolar Super-Earth planets. We report recent technical advances and techniques enabling falling sphere viscosity measurements in single- and double-stage DIA-type multi-anvil apparatus. For the experiments we used presses with a maximum load of 250 tons and 1750 tons. We anticipate that our system will enable viscosity measurements up to the maximum pressure for non-diamond anvils, i.e. pressures up to some 30 GPa. For the development of the new set ups the deformation of the cell assemblies were analyzed by X-ray absorption tomography at beamline W II at DESY/HASYLAB after the high pressure runs. These analysis gave considerable insights into strategies for improving the cell assembly with the result that the optimized assemblies could be used at much higher pressures without blow-outs. We think this approach is much faster and more beneficial than the classical way of trial and error. Additionally to prevent high pressure blow outs the task was to make the whole melting chamber accessible for the high pressure X-radiography system up to the maximum pressures. This way the accuracy and reliability of the measurements can be improved. For this goal we used X-ray transparent cBN-anvils at the single-stage DIA large volume press. Because this material is recently not available for the cube size of 32 mm this aproach did not work for the double-stage DIA. As a very useful and economical alternative we used slotted carbide anvils filled with fired pyrophyllite bars. To improve the frame quality of the platinum spheres taken by the CCD-camera the energy of the monochromatic X-rays had to be increased to 100 keV. The resulting ascent of scattered radiation required a new design of the X-radiography unit. Our results are demonstrated with viscosity measurements following Stokes law by evaluation of X-radiography sequences taken by a CCD-camera at pressures of 5 GPa as well as 10 GPa and temperatures of 1890 K. As the first result we could increase the maximum pressure range of published viscosity measurements with dacite melts by almost factor 1.5 (see Tinker et al., 2004).

Alunite in the Pascua-Lama high-sulfidation deposit: Constraints on alteration and ore deposition using stable isotope geochemistry

USGS Publications Warehouse

Deyell, C.L.; Leonardson, R.; Rye, R.O.; Thompson, J.F.H.; Bissig, T.; Cooke, D.R.

2005-01-01

The Pascua-Lama high-sulfidation system, located in the El Indio-Pascua belt of Chile and Argentina, contains over 16 million ounces (Moz) Au and 585 Moz Ag. The deposit is hosted primarily in granite rocks of Triassic age with mineralization occurring in several discrete Miocene-age phreatomagmatic breccias and related fracture networks. The largest of these areas is Brecha Central, which is dominated by a mineralizing assemblage of alunite-pyrite-enargite and precious metals. Several stages of hydrothermal alteration related to mineralization are recognized, including all types of alunite-bearing advanced argillic assemblages (magmatic-hydrothermal, steam-heated, magmatic steam, and supergene). The occurrence of alunite throughout the paragenesis of this epithermal system is unusual and detailed radiometric, mineralogical, and stable isotope studies provide constraints on the timing and nature of alteration and mineralization of the alunite-pyiite-enargite assemblage in the deposit. Early (preore) alteration occurred prior to ca. 9 Ma and consists of intense silicic and advanced argillic assemblages with peripheral argillic and widespread propylitic zones. Alunite of this stage occurs as fine intergrowths of alunite-quartz ?? kaolinite, dickite, and pyrophyllite that selectively replaced feldspars in the host rock. Stable isotope systematics suggest a magmatic-hydrothermal origin with a dominantly magmatic fluid source. Alunite is coeval with the main stage of Au-Ag-Cu mineralization (alunite-pyrite-enargite assemblage ore), which has been dated at approximately 8.8 Ma. Ore-stage alunite has an isotopic signature similar to preore alunite, and ?? 34Salun-py data indicate depositional temperatures of 245?? to 305??C. The ??D and ?? 18O data exclude significant involvement of meteoric water during mineralization and indicate that the assemblage formed from H2S-dominated magmatic fluids. Thick steam-heated alteration zones are preserved at the highest elevations in the deposit and probably formed from oxidation of H2S during boiling of the magmatic ore fluids. Coarsely crystalline magmatic steam alunite (8.4 Ma) is restricted to the near-surface portion of Brecha Central. Postmineral alunite ?? jarosite were previosly interpreted to be supergene crosscutting veins and overgrowths, although stable isotope data suggest a mixed magmatic-meteoric origin for this late-stage alteration. Only late jarosite veinlets (8.0 Ma) associated with fine-grained pseudocubic alunite have a supergene isotopic signature. The predominanca of magmatic fluids recorded throughout the paragenesis of the Pascua system is atypical for high-sulfidation deposits, which typically envolve significant meteoric water in near-surface and peripheral alteration and, in some systems, even ore deposition. A Pascua, the strong magmatic signature of both alteration and main-stage (alunite-pyrite-enargite assemblage) ore is attributed to limited availability of meteoric fluids. This is in agreement with published data for the El Indio-Pascua belt, indicating an event of uplift and subsequent pediment incision, as well as a transition from semiarid to arid climatic conditions, during the formation of the deposit in the mid to late Miocene. ?? 2005 Society of Economic Geologists, Inc.

Chemical Mobility, Variability, and Components of the Yaxcopoil Impact Melt Breccia Matrix as a Function of Depth

NASA Astrophysics Data System (ADS)

Nelson, M. J.; Newsom, H.

2005-05-01

The matrix in the Yaxcopoil 1 drill core produced by the Chicxulub event is semi-amorphous, containing clays and evidence for elemental mobility. We analyzed matrix in impact melt and suevitic breccia samples from the drill hole to detect mineralogical and chemical variability with depth in upper and lower core samples. SEM, microprobe, Cameca 4f ion probe, and XRD were used to determine chemical mobility and variation, and clay structure in several YAX samples, covering the top five units, at a depth range of about 61m. We investigated the possibility of glass, clay, and metastable eutectic dehydroxylates as components in the matrix. Matrix in upper suevite is not optically distinct, but a type of groundmass, with an admixture of calcite, crystallites, and several melt phases with melt texture indicative of simultaneous formation. With an increase in depth, flow tex-ture in the melt matrix is obvious around clasts on all scales, indicating a different temporal relationship than in the upper suevite. Chemically, the matrix is Si and Mg rich in most samples. With an increase in depth, the bulk matrix contains a strong linear increase of Mg, and a decrease of Al. With depth, the increasingly Mg-rich matrix exhibits a stronger flow texture. Aluminum also appears mobile, with enrichments mostly around clasts and veins. In addition, Li and B are strongly correlated, and decrease linearly with depth. The matrix contains materials that appear to be chemically and structurally consistent with smectites at all depths. The compositions range from that of an average montmorillonite in the uppermost units to that of a magnesium rich saponite in the lower units. Aside from the exis-tence of clays, we are considering the possibility that the matrix could contain metastable condensates from the im-pact dust cloud. As an introductory step to test this, matrix compositions were plotted among metastable eutectic dehydroxylate (MED) end members. This produced a remarkably co-linear trend with the join between MED pyro-phyllite and MED serpentine. High resolution equipment will be used to follow up on this idea. The matrix in lower samples had more element mobility, and likely more chemical reactions occurring among phases. An increase in mobility and transport of Mg could help explain this bulk enrichment in lower samples. In addition, variations in the original target material would logically contribute to chemical variations in the matrix. Dolomite and mafic minerals present at greater depth could react with matrix in the melt breccia, while dust and clay may exist in variable amounts within the drill core samples. The linear trend toward metastable dehydroxylate eutec-tic compositions is an encouraging first step to further investigate the possible existence of condensates from the impact cloud within the matrix.

Glaucophane chloritoid-bearing assemblages from NE Oman: petrologic significance and a petrogenetic grid for high P metapelites

NASA Astrophysics Data System (ADS)

El-Shazly, A. K.; Liou, J. G.

1991-04-01

Pelitic layers and lenses interbedded with blueschists and eclogites in Saih Hatat, NE Oman contain chloritoid- and sodic amphibole-bearing mineral assemblages that are useful for reconstructing the P-T history of the area. Textural and mineral chemical relations suggest that coexisting glaucophane (Gln) and chloritoid (Ctd) formed at the expense of chlorite (Chl)+paragonite (Pg) and later broke down to garnet (Gt)+Pg during prograde metamorphism according to the reaction: Gln+Ctd+Qz=Gt+Pg+H2O. During retrogression, Gln and Chl first formed at the expense of Gt and Pg, followed by the breakdown of Ctd and Gt to Chl. The final stages of retrogression are marked by the breakdown of Gln to an aggregate of Chl+albite (Ab). A projection from quartz (Qz), H2O and phengite (Ph) on the (Al2O3+Fe2O3)-(FeO+MgO)-Na2O plane in the system NFMASH is best suited for the representation of the phase relations in high P metapelites. Petrogenetic grids for the model systems NMASH and NFASH were calculated using program GEO-CALC (Berman et al. 1987) and its database (Berman 1988) after the retrieval of S{i/o}and ΔH{f/o}for Gln and Ctd by mathematical programming and calculating all possible reactions among Gln, Ctd, Chl, jadeite (Jd), Ab, Gt, Pg, talc (Tc), pyrophyllite (Prl) and kyanite (Ky). The calculated petrogenetic grid for the system NFASH shows that Fe-Ctd and ferroglaucophane coexist at P>6.5 kbar and T<525°C, whereas the assemblage: Ct-Gln-Pg is stable between 435 and 630°C and P>6 kbar. This grid is consistent with the P-T estimates for high P metapelites from Oman, New Caledonia, Seward Peninsula, Ile de Groix, Sifnos and Peloponnese, where Gln+Ctd bearing units are interbedded with cofacial mafic blueschists and eclogites. The grid also explains the observed textural relations in the metapelites of Oman, and is consistent with the “clockwise” P-T path proposed for this area, but differs from the grids of Guiraud et al. (1990) in showing a larger stability field for Gln+Ctd that overlaps with the stability fields of Jd+Qz as well as Ab. The petrogenetic grid calculated for the system NMASH shows that Mg-Ctd+Gln-bearing assemblages require unusually low geothermal gradients to form in metapelites. It also shows that Mg-rich Ctd+Tc coexist at high pressures over a wider P-T range than predicted by Guiraud et al. (1990). This grid can therefore be applied to high P metamorphic assemblages from the eastern and western Alps.

Methodology or method? A critical review of qualitative case study reports.

PubMed

Hyett, Nerida; Kenny, Amanda; Dickson-Swift, Virginia

2014-01-01

Despite on-going debate about credibility, and reported limitations in comparison to other approaches, case study is an increasingly popular approach among qualitative researchers. We critically analysed the methodological descriptions of published case studies. Three high-impact qualitative methods journals were searched to locate case studies published in the past 5 years; 34 were selected for analysis. Articles were categorized as health and health services (n=12), social sciences and anthropology (n=7), or methods (n=15) case studies. The articles were reviewed using an adapted version of established criteria to determine whether adequate methodological justification was present, and if study aims, methods, and reported findings were consistent with a qualitative case study approach. Findings were grouped into five themes outlining key methodological issues: case study methodology or method, case of something particular and case selection, contextually bound case study, researcher and case interactions and triangulation, and study design inconsistent with methodology reported. Improved reporting of case studies by qualitative researchers will advance the methodology for the benefit of researchers and practitioners.

Integrating Human Factors into Crew Exploration Vehicle (CEV) Design

NASA Technical Reports Server (NTRS)

Whitmore, Mihriban; Holden, Kritina; Baggerman, Susan; Campbell, Paul

2007-01-01

The purpose of this design process is to apply Human Engineering (HE) requirements and guidelines to hardware/software and to provide HE design, analysis and evaluation of crew interfaces. The topics include: 1) Background/Purpose; 2) HE Activities; 3) CASE STUDY: Net Habitable Volume (NHV) Study; 4) CASE STUDY: Human Modeling Approach; 5) CASE STUDY: Human Modeling Results; 6) CASE STUDY: Human Modeling Conclusions; 7) CASE STUDY: Human-in-the-Loop Evaluation Approach; 8) CASE STUDY: Unsuited Evaluation Results; 9) CASE STUDY: Suited Evaluation Results; 10) CASE STUDY: Human-in-the-Loop Evaluation Conclusions; 11) Near-Term Plan; and 12) In Conclusion

Enhancing the quality of case studies in health services research.

PubMed Central

Yin, R K

1999-01-01

OBJECTIVE: To provide guidance on improving the quality of case studies in health services research. DATA SOURCES: Secondary data, drawing from previous case study research. RESEARCH DESIGN: Guidance is provided to two audiences: potential case study investigators (eight items) and reviewers of case study proposals (four additional items). PRINCIPAL FINDINGS: The guidance demonstrates that many operational steps can be undertaken to improve the quality of case studies. These steps have been a hallmark of high-quality case studies in related fields but have not necessarily been practiced in health services research. CONCLUSIONS: Given higher-quality case studies, the case study method can become a valuable tool for health services research. Images Figure 3 PMID:10591280

Developing the DESCARTE Model: The Design of Case Study Research in Health Care.

PubMed

Carolan, Clare M; Forbat, Liz; Smith, Annetta

2016-04-01

Case study is a long-established research tradition which predates the recent surge in mixed-methods research. Although a myriad of nuanced definitions of case study exist, seminal case study authors agree that the use of multiple data sources typify this research approach. The expansive case study literature demonstrates a lack of clarity and guidance in designing and reporting this approach to research. Informed by two reviews of the current health care literature, we posit that methodological description in case studies principally focuses on description of case study typology, which impedes the construction of methodologically clear and rigorous case studies. We draw from the case study and mixed-methods literature to develop the DESCARTE model as an innovative approach to the design, conduct, and reporting of case studies in health care. We examine how case study fits within the overall enterprise of qualitatively driven mixed-methods research, and the potential strengths of the model are considered. © The Author(s) 2015.

Case Study: Testing with Case Studies

ERIC Educational Resources Information Center

Herreid, Clyde Freeman

2015-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue discusses using case studies to test for knowledge or lessons learned.

Methodology or method? A critical review of qualitative case study reports

PubMed Central

Hyett, Nerida; Kenny, Amanda; Dickson-Swift, Virginia

2014-01-01

Despite on-going debate about credibility, and reported limitations in comparison to other approaches, case study is an increasingly popular approach among qualitative researchers. We critically analysed the methodological descriptions of published case studies. Three high-impact qualitative methods journals were searched to locate case studies published in the past 5 years; 34 were selected for analysis. Articles were categorized as health and health services (n=12), social sciences and anthropology (n=7), or methods (n=15) case studies. The articles were reviewed using an adapted version of established criteria to determine whether adequate methodological justification was present, and if study aims, methods, and reported findings were consistent with a qualitative case study approach. Findings were grouped into five themes outlining key methodological issues: case study methodology or method, case of something particular and case selection, contextually bound case study, researcher and case interactions and triangulation, and study design inconsistent with methodology reported. Improved reporting of case studies by qualitative researchers will advance the methodology for the benefit of researchers and practitioners. PMID:24809980

Case Study: Writing a Journal Case Study

ERIC Educational Resources Information Center

Prud'homme-Genereux, Annie

2016-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue describes incorporating a journal article into the classroom by first converting it into a case study.

Fostering Entrepreneurship through Business Incubation: The Role and Prospects of Postsecondary Vocational-Technical Education. Report 2: Case Studies.

ERIC Educational Resources Information Center

Hernandez-Gantes, Victor M.; And Others

This report presents nine case studies featuring efforts to foster community development through business incubation and entrepreneurial programs at two-year colleges. A background section discusses case description, and organization and format of case studies. The second section describes the case study design. Each case study is introduced with…

The Misconception of Case-Control Studies in the Plastic Surgery Literature: A Literature Audit.

PubMed

Hatchell, Alexandra C; Farrokhyar, Forough; Choi, Matthew

2017-06-01

Case-control study designs are commonly used. However, many published case-control studies are not true case-controls and are in fact mislabeled. The purpose of this study was to identify all case-control studies published in the top three plastic surgery journals over the past 10 years, assess which were truly case-control studies, clarify the actual design of the articles, and address common misconceptions. MEDLINE, Embase, and Web of Science databases were searched for case-control studies in the three highest-impact factor plastic surgery journals (2005 to 2015). Two independent reviewers screened the resulting titles, abstracts, and methods, if applicable, to identify articles labeled as case-control studies. These articles were appraised and classified as true case-control studies or non-case-control studies. The authors found 28 articles labeled as case-control studies. However, only six of these articles (21 percent) were truly case-control designs. Of the 22 incorrectly labeled studies, one (5 percent) was a randomized controlled trial, three (14 percent) were nonrandomized trials, two (9 percent) were prospective comparative cohort designs, 14 (64 percent) were retrospective comparative cohort designs, and two (9 percent) were cross-sectional designs. The mislabeling was worse in recent years, despite increases in evidence-based medicine awareness. The majority of published case-control studies are not in fact case-control studies. This misunderstanding is worsening with time. Most of these studies are actually comparative cohort designs. However, some studies are truly clinical trials and thus a higher level of evidence than originally proposed.

Case Study: Puttin' on the Ritz: How to Put Science into Cases

ERIC Educational Resources Information Center

Herreid, Clyde Freeman

2017-01-01

There are multiple ways to put science into a case. This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue discusses different ways of presenting science in case studies.

Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry

NASA Astrophysics Data System (ADS)

Chukanov, Nikita V.; Jonsson, Erik; Aksenov, Sergey M.; Britvin, Sergey N.; Rastsvetaeva, Ramiza K.; Belakovskiy, Dmitriy I.; Van, Konstantin V.

2017-11-01

The new mineral roymillerite Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, related to britvinite and molybdophyllite, was discovered in a Pb-rich assemblage from the Kombat Mine, Grootfontein district, Otjozondjupa region, Namibia, which includes also jacobsite, cerussite, hausmannite, sahlinite, rhodochrosite, barite, grootfonteinite, Mn-Fe oxides, and melanotekite. Roymillerite forms platy single-crystal grains up to 1.5 mm across and up to 0.3 mm thick. The new mineral is transparent, colorless to light pink, with a strong vitreous lustre. Cleavage is perfect on (001). Density calculated using the empirical formula is equal to 5.973 g/cm3. Roymillerite is optically biaxial, negative, α = 1.86(1), β ≈ γ = 1.94(1), 2 V (meas.) = 5(5)°. The IR spectrum shows the presence of britvinite-type tetrahedral sheets, {CO}3^{2 - }, {BO}3^{3 - }, and OH- groups. The chemical composition is (wt%; electron microprobe, H2O and CO2 determined by gas chromatography, the content of B2O3 derived from structural data): MgO 4.93, MnO 1.24, FeO 0.95, PbO 75.38, B2O3 0.50, Al2O3 0.74, CO2 5.83, SiO2 7.90, H2O 1.8, total 99.27. The empirical formula based on 83 O atoms pfu (i.e. Z = 1) is Pb24.12Mg8.74Mn1.25Fe0.94B1.03Al1.04C9.46Si9.39H14.27O83. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is triclinic, space group P \\bar{1}, with a = 9.315(1), b = 9.316(1), c = 26.463(4) Å, α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°, V = 1971.2(6) Å3. The crystal structure of roymillerite is based built by alternating pyrophyllite-type TOT-modules Mg9(OH)8[(Si,Al)10O28] and I-blocks Pb24(OH)6O4(CO3)10(BO3,SiO4). The strongest lines of the powder X-ray diffraction pattern [ d, Å (I, %) ( hkl)] are: 25.9 (100) (001), 13.1 (11) (002), 3.480 (12) (017, 107, -115, 1-15), 3.378 (14) (126, 216), 3.282 (16) (-2-15, -1-25), 3.185 (12) (-116, 1-16), 2.684 (16) (031, 301, 030, 300, 332, -109, 0-19, 1-18), 2.382 (11) (0.0.-11). Roymillerite is named to honor Dr. Roy McG. Miller for his important contributions to the knowledge of the geology of Namibia.

Internally consistent thermodynamic data for high-pressure and ultrahigh-pressure phases in the system CaO-MgO-Al2O3-SiO2-H2O

NASA Astrophysics Data System (ADS)

Grevel, K. D.

2008-12-01

In order to enable reliable calculations of phase relations among high-pressure phases the Berman [1] data set was augmented by data for the high-pressure phases stishovite (stv), topaz-OH (toz-OH), phase pi (pi), Mg-staurolite (Mg-st), Mg-sursassite (Mg-sur), and Mg-chloritoid (Mg-cld) using a similar optimization technique as described by Berman et al. [2]. The data of several other phases of the system CaO-MgO- Al2O3-SiO2-H2O obtained in the Berman data base were slightly refined to keep the consistency to the reversal brackets and the originally measured data: andalusite (and), clinochlore (chl), coesite (cs), diaspore (dsp), kaolinite (kln), kyanite (ky), lawsonite (lws), pyrophyllite (prl), sillimanite (sil), zoisite (zo). CP-data were kept constant [1] or estimated [3]. phase; ΔfH0298 (kJ mol-1); S0298 (J K-1 mol-1); V0298 (J K-1 mol-1); v1×105 (bar-1); v2×1012 (bar-2); v3×105 (K-1); v4×108 (K-2) and; -2589.857; 91.47; 5.146; -0.0653; 0.000; 2.291; 0.170 chl; -8903.532; 437.92; 21.000; -0.1328; 3.837; 2.142; 0.962 Mg-cld; -3551.657; 142.20; 6.874; -0.0692; 0.000; 2.544; 0.000 cs; -907.510; 39.63; 2.064; -0.0998; 1.823; 0.620; 0.960 dsp; -999.115; 35.22; 1.776; -0.0719; 0.629; 3.245; 0.684 kln; -4119.400; 204.18; 9.952; -0.1200; 0.000; 3.200; 0.000 ky; -2593.767; 82.71; 4.408; -0.0593; 1.021; 1.730; 0.787 lws; -4866.665; 228.04; 10.155; -0.0825; 0.000; 3.339; 0.000 Mg-sur; -13907.329; 608.39; 26.888; -0.0826; 0.923; 3.187; 0.087 pi; -9586.742; 403.23; 18.559; -0.0678; 0.000; 2.254; 0.000 prl; -5640.501; 239.43; 12.782; -0.1800; 0.000; 2.621; 0.000 sil; -2586.169; 95.40; 4.984; -0.0601; 1.341; 1.138; 0.605 Mg-st; -24998.289; 944.53; 44.260; -0.0579; 0.000; 2.017; 0.000 stv; -870.861; 25.59; 1.401; -0.0318; 0.000; 1.849; 0.000 toz-OH; -2885.939; 117.40; 5.352; -0.0630; 0.000; 1.938; 0.000 zo; -6889.494; 297.20; 13.565; -0.0695; 0.000; 2.752; 0.000 References [1] R.G. Berman, J. Petrol., 1988, 29, 445 [2] R.G. Berman et al., J. Petrol., 1986, 27, 1331 [3] R.G. Berman, T.H. Brown, Con. Min. Pet., 1985, 89, 168

Experimental Constraints on Hot Spring Fluid Chemistry in Back Arc Basins

NASA Astrophysics Data System (ADS)

Schaen, A. T.; Saccocia, P. J.; Seewald, J.

2010-12-01

Many axial hot springs from back-arc basins are characterized by low pH and high metal concentrations compared to fluids from the mid-ocean ridge. Such differences are likely related to the presence of felsic crust and the involvement of acidic magmatic fluids in back-arc hydrothermal systems. Previous experiments that reacted fresh andesite with seawater at elevated T and P yielded pH values significantly higher than those observed in back-arc basin hot springs. Moreover, ocean drilling beneath back-arc basin hot springs revealed acid-sulfate alteration assemblages, suggesting at least transient involvement of magmatic fluids. Here we report the results of two laboratory experiments designed to assess fluid chemistry in equilibrium with acid-sulfate alteration assemblages at sub-seafloor conditions typically associated with back-arc hot springs. Both experiments reacted a K-Ca-Na-Cl fluid with a pyrophyllite-pyrite-anhydrite-quartz assemblage (PPAQ). In addition, alunite was added to the assemblage in one experiment (PPAQA). Both experiments were conducted in a flexible-cell hydrothermal apparatus utilizing an inert Au-Ti reaction cell. Fluid samples were withdrawn from the reaction cell as a function of time and temperature and analyzed for major anions, cations, pH (25C), H2, and H2S to monitor reaction progress. In the PPAQ experiment, pH varied from 3.1 to 3.4 from 350 to 365C at 0.25 Kb. At 385C, 0.26 Kb, pH dropped to 2.74, close to the value observed in many BAB hot springs. H2S varied from 2 mmol/kg at 350C, 0.25 Kb to 11 mmol/kg at 385C, 0.26 Kb. In general, K decreased and Ca increased with increasing T and decreasing P while SO4 remained low (<1 mmol/kg). In the PPAQA experiment, fluid pH was much lower, varying from 2.2 to 1.5 from 250 to 350C, 0.25 Kb. H2S was low (<1 mmol/kg) at these same conditions. Similarly, H2 was <0.003 mmol/kg, consistent with relatively oxidizing conditions. K concentration remained nearly constant while Ca increased with decreasing T. SO4 varied inversely with Ca, varying from 35 to 4 mmol/kg from 350 to 250C, respectively. Thus, the presence of alunite in the alteration assemblage yields an extremely acid fluid, depleted in H2S and enriched in SO4 compared to fluids from the PPAQ experiment. These results suggest that the composition of hot spring fluids from back-arc environments is consistent with fluid-mineral equilibria involving acid-sulfate mineral assemblages. Such assemblages may be produced by previous episodes of magmatic degassing. Accordingly, the presence of highly acidic vent fluids may reflect an important role for magmatic fluids during crustal alteration processes, but does not require the presence of an actively degassing magma chamber.

The Third Dimension of an Active Back-arc Hydrothermal System: ODP Leg 193 at PACMANUS

NASA Astrophysics Data System (ADS)

Binns, R.; Barriga, F.; Miller, D.

2001-12-01

This first sub-seafloor examination of an active hydrothermal system hosted by felsic volcanics, at a convergent margin, obtained drill core from a high-T "smoker" site (penetrated to sim200 mbsf) and a low-T site of diffuse venting (~400mbsf). We aimed to delineate the lateral and vertical variability in mineralisation and alteration patterns, so as to understand links between volcanological, structural and hydrothermal phenomena and the sources of fluids, and to establish the nature and extent of microbial activity within the system. Technological breakthroughs included deployment of a new hard-rock re-entry system, and direct comparison in a hardrock environment of structural images obtained by wireline methods and logging-while-drilling. The PACMANUS hydrothermal site, at the 1700m-deep crest of a 500m-high layered sequence of dacitic lavas, is notable for baritic massive sulfide chimneys rich in Cu, Zn, Au and Ag. Below an extensive cap 5-40m thick of fresh dacite-rhyodacite, we found unexpectedly pervasive hydrothermal alteration of vesicular and flow-banded precursors, accompanied by variably intense fracturing and anhydrite-pyrite veining. Within what appears one major hydrothermal event affecting the entire drilled sequence, there is much overprinting and repetition of distinctly allochemical argillaceous (illite-chlorite), acid-sulfate (pyrophyllite-anhydrite) and siliceous assemblages. The alteration profiles include a transition from metastable cristobalite to quartz at depth, and are similar under low-T and high-T vent sites but are vertically condensed in a manner suggesting higher thermal gradients beneath the latter. The altered rocks are surprisingly porous (average 25%). Retention of intergranular pore spaces and open vesicles at depth implies elevated hydrothermal pressures, whereas evidence from fluid inclusions and hydrothermal brecciation denotes local or sporadic phase separation. A maximum measured temperature of 313 degC measured 8 days after drilling (360 mbsf at the diffuse venting site), if indicative of thermal gradient, suggests the presence of a very shallow ( ~1.5 km below seafloor) magmatic heat source. While isotopic characteristics of anhydrite suggest an irregularly varying component of magmatic fluid, the abundance of this mineral implies a substantial role for circulating seawater within the subsurface hydrothermal system. Other than the near-ubiquitous, fine grained disseminated pyrite in altered rocks, we found little sulfide mineralisation. Pyritic vein networks and breccias are extensive in the rapidly penetrated, but poorly recovered, interval down to 120 mbsf within our "high-T end-member" hole spudded on a mound surmounted by active (280 degC) chimneys. Anhydrite and open cavities possibly dominate this interval, from which a possible example of subhalative semi-massive sulfide containing chalcopyrite and some sphalerite was recovered near 30 mbsf. At the low-T and high-T vent sites respectively, anaerobic microbes were recorded by direct counting at depths down to 99 and 78 mbsf, and in 90 degC cultivation experiments at 69-107 and 99-129 mbsf. >http://www-odp.tamu.edu/publications/prelim/193

Coffee, decaffeinated coffee, tea and cancer of the colon and rectum: a review of epidemiological studies, 1990-2003.

PubMed

Tavani, Alessandra; La Vecchia, Carlo

2004-10-01

The literature from 1990 to 2003 on the relation between coffee, decaffeinated coffee, tea and colorectal cancer risk has been reviewed. For the relation with coffee, three cohort (517 total cases) and nine case-control studies (7555 cases) analysed colon cancer; three cohort (307 cases) and four case-control studies (2704 cases) rectal cancer; six case-control studies (854 cases) colorectal cancer. For colon cancer most case-control studies found risk estimates below unity; the results are less clear for cohort studies. No relation emerged for rectal cancer. A meta-analysis, including five cohort and twelve case-control studies, reported a pooled relative risk of 0.76 (significant). Any methodological artefact is unlikely to account for the consistent inverse association in different countries and settings. Plausible biological explanations include coffee-related reductions of cholesterol, bile acids and neutral sterol secretion in the colon; antimutagenic properties of selected coffee components; increased colonic motility. Decaffeinated coffee was not related to either colon or rectal cancer in three case-control studies. No overall association between tea and either colon or rectal cancer risk emerged in seven cohort (1756 total cases of colon, 759 of rectal and 60 of colorectal cancer) and 12 case-control studies (8058 cases of colon, 4865 of rectal, 604 of colorectal cancer).

Al-Qaeda in Iraq (AQI): An Al-Qaeda Affiliate Case Study

DTIC Science & Technology

2017-10-01

a comparative methodology that included eight case studies on groups affiliated or associated with Al-Qaeda. These case studies were then used as a... methodology that included eight case studies on groups affiliated or associated with Al-Qaeda. These case studies were then used as a dataset for cross...Case Study Zack Gold With contributions from Pamela G. Faber October 2017 This work was performed under Federal Government

Discovering the Future of the Case Study Method in Evaluation Research.

ERIC Educational Resources Information Center

Yin, Robert K.

1994-01-01

It is assumed that evaluators of the future will still be interested in case study methodology. Scenarios that ignore a case study method, that look back to a distinctive case study method, and that see the case study method as an integrating force in the qualitative-quantitative debate are explored. (SLD)

Qualitative Case Study Research as Empirical Inquiry

ERIC Educational Resources Information Center

Ellinger, Andrea D.; McWhorter, Rochell

2016-01-01

This article introduces the concept of qualitative case study research as empirical inquiry. It defines and distinguishes what a case study is, the purposes, intentions, and types of case studies. It then describes how to determine if a qualitative case study is the preferred approach for conducting research. It overviews the essential steps in…

Assembling a Case Study Tool Kit: 10 Tools for Teaching with Cases

ERIC Educational Resources Information Center

Prud'homme-Généreux, Annie

2017-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. The author shares the strategies and tools that teachers can use to manage a case study classroom effectively.

The case-control design in veterinary sciences: A survey.

PubMed

Cullen, Jonah N; Sargeant, Jan M; Makielski, Kelly M; O'Connor, Annette M

2016-11-01

The case-control study design is deceptively simple. However, many design considerations influence the estimated effect measure. An investigation of case-control studies in the human health literature suggested that some of these considerations are not described in reports of case-control studies. Our hypothesis was that the majority of veterinary studies labeled as case-controls would be incident density designs, and many would not interpret the effect measure obtained from those studies as the rate ratio rather than the odds ratio. Reference databases were searched for author-designated case-control studies. A survey of 100 randomly selected studies was conducted to examine the different design options described and estimated effect measures. Of the 100 author-identified case-control studies, 83 assessed an exposure-outcome association and, of those, only 54 (65.1%) sampled the study population based on an outcome and would thus be considered case-control designs. Twelve studies were incidence density designs but none used this terminology. Of the studies that reported an odds ratio as the effect measure, none reported on additional considerations that would have enabled a more interpretable result. This survey indicated many case-control-labeled studies were not case-control designs and among case-control studies, key design aspects were not often described. The absence of information about study design elements and underlying assumptions in case-control studies limits the ability to establish the effect measured by the study and the evidentiary value of the study might be underestimated. Copyright © 2016 Elsevier B.V. All rights reserved.

Beyond Clinical Case Studies in Psychoanalysis: A Review of Psychoanalytic Empirical Single Case Studies Published in ISI-Ranked Journals.

PubMed

Meganck, Reitske; Inslegers, Ruth; Krivzov, Juri; Notaerts, Liza

2017-01-01

Single case studies are at the origin of both theory development and research in the field of psychoanalysis and psychotherapy. While clinical case studies are the hallmark of psychoanalytic theory and practice, their scientific value has been strongly criticized. To address problems with the subjective bias of retrospective therapist reports and uncontrollability of clinical case studies, systematic approaches to investigate psychotherapy process and outcome at the level of the single case have been developed. Such empirical case studies are also able to bridge the famous gap between academic research and clinical practice as they provide clinically relevant insights into how psychotherapy works. This study presents a review of psychoanalytic empirical case studies published in ISI-ranked journals and maps the characteristics of the study, therapist, patient en therapies that are investigated. Empirical case studies increased in quantity and quality (amount of information and systematization) over time. While future studies could pay more attention to providing contextual information on therapist characteristics and informed consent considerations, the available literature provides a basis to conduct meta-studies of single cases and as such contribute to knowledge aggregation.

Beyond Clinical Case Studies in Psychoanalysis: A Review of Psychoanalytic Empirical Single Case Studies Published in ISI-Ranked Journals

PubMed Central

Meganck, Reitske; Inslegers, Ruth; Krivzov, Juri; Notaerts, Liza

2017-01-01

Single case studies are at the origin of both theory development and research in the field of psychoanalysis and psychotherapy. While clinical case studies are the hallmark of psychoanalytic theory and practice, their scientific value has been strongly criticized. To address problems with the subjective bias of retrospective therapist reports and uncontrollability of clinical case studies, systematic approaches to investigate psychotherapy process and outcome at the level of the single case have been developed. Such empirical case studies are also able to bridge the famous gap between academic research and clinical practice as they provide clinically relevant insights into how psychotherapy works. This study presents a review of psychoanalytic empirical case studies published in ISI-ranked journals and maps the characteristics of the study, therapist, patient en therapies that are investigated. Empirical case studies increased in quantity and quality (amount of information and systematization) over time. While future studies could pay more attention to providing contextual information on therapist characteristics and informed consent considerations, the available literature provides a basis to conduct meta-studies of single cases and as such contribute to knowledge aggregation. PMID:29046660

Does Case-Study Methodology Lack Rigour? The Need for Quality Criteria for Sound Case-Study Research, as Illustrated by a Recent Case in Secondary and Higher Education

ERIC Educational Resources Information Center

Kyburz-Graber, Regula

2004-01-01

There is a tendency to use case-study research methodology for research issues aiming at simply describing a complex situation, and to draw conclusions with insufficient rigour. Sound case-study research, however, follows discriminate rules which can be described in all the dimensions of a full case-study research process. This paper examines…

[Application of nested case-control study on safe evaluation of post-marketing traditional Chinese medicine injection].

PubMed

Xiao, Ying; Zhao, Yubin; Xie, Yanming

2011-10-01

The nested case-control study design (or the case-control in a cohort study) is described here as a new study design used in safe evaluation of post-marketing traditional Chinese medicine injection. In the nested case-control study, cases of a disease that occur in a defined cohort are identified and, for each, a specified number of matched controls is selected from among those in the cohort who have not developed the disease by the time of disease occurrence in the case. For many research questions, the nested case-control design potentially offers impressive reductions in costs and efforts of data collection and analysis compared with the full cohort approach, with relatively minor loss in statistical efficiency. The nested case-control design is particularly advantageous for studies in safe evaluation of post-marketing traditional Chinese medicine injection. Some examples of the application of nested case-control study were given.

Qualitative case study methodology in nursing research: an integrative review.

PubMed

Anthony, Susan; Jack, Susan

2009-06-01

This paper is a report of an integrative review conducted to critically analyse the contemporary use of qualitative case study methodology in nursing research. Increasing complexity in health care and increasing use of case study in nursing research support the need for current examination of this methodology. In 2007, a search for case study research (published 2005-2007) indexed in the CINAHL, MEDLINE, EMBASE, PsychINFO, Sociological Abstracts and SCOPUS databases was conducted. A sample of 42 case study research papers met the inclusion criteria. Whittemore and Knafl's integrative review method guided the analysis. Confusion exists about the name, nature and use of case study. This methodology, including terminology and concepts, is often invisible in qualitative study titles and abstracts. Case study is an exclusive methodology and an adjunct to exploring particular aspects of phenomena under investigation in larger or mixed-methods studies. A high quality of case study exists in nursing research. Judicious selection and diligent application of literature review methods promote the development of nursing science. Case study is becoming entrenched in the nursing research lexicon as a well-accepted methodology for studying phenomena in health and social care, and its growing use warrants continued appraisal to promote nursing knowledge development. Attention to all case study elements, process and publication is important in promoting authenticity, methodological quality and visibility.

Online Learning and Teaching with Technology: Case Studies, Experience and Practice. Case Studies of Teaching in Higher Education.

ERIC Educational Resources Information Center

Murphy, David, Ed.; Walker, Rob, Ed.; Webb, Graham, Ed.

This book contains case studies that look at using technology in a wide range of situations, from fully online courses to more traditional face-to-face settings. The case studies deal with issues related to student interaction, teaching and assessment, planning and development, and policy. The following case studies are included: (1) "Flame…

Case Study: Mini-Case Studies: Small Infusions of Active Learning for Large-Lecture Courses

ERIC Educational Resources Information Center

Carloye, Lisa

2017-01-01

In this article, the author introduces the usage of case studies to be an excellent method for engaging students through stories. The author notes she developed a series of mini-case studies that can be implemented, with a little advance preparation, within a 10- to 15-minute window during lecture. What makes them "mini" case studies?…

Lively Discussions vs. Discussions of Substance: Making the Case for Guided Case Study.

ERIC Educational Resources Information Center

Woloshin/Lerman, Phyllis

1996-01-01

Discusses the history and purpose of the case study method used to stimulate in-class discussion. Advocates the use of the guided case study method to ensure that substantive discussions take place and provides nine steps for using the method. Includes a sample case study worksheet. (11 citations) (BCY)

Case Study: Guidelines for Producing Videos to Accompany Flipped Cases

ERIC Educational Resources Information Center

Prud'homme-Généreux, Annie; Schiller, Nancy A.; Wild, John H.; Herreid, Clyde Freeman

2017-01-01

Three years ago, the "National Center for Case Study Teaching in Science" (NCCSTS) was inspired to merge the case study and flipped classroom approaches. The resulting project aimed to create the materials required to teach a flipped course in introductory biology by assigning videos as homework and case studies in the classroom. Three…

Implementation of case studies in undergraduate didactic nursing courses: a qualitative study.

PubMed

Dutra, Danette K

2013-07-04

The implementation of unfolding scenario-based case studies in the didactic classroom is associated with learner-centered education. The utilization of learner-centered pedagogies, such as case studies, removes the focus from the instructor and instead places it on the student. Learner-centered pedagogies are believed to improve students' levels of cognition. The purpose of this study was to examine how nurse educators are implementing the pedagogies of case studies in their undergraduate didactic courses. The goal was to examine, document, report, and, ultimately, implement the strategies. Purposeful sampling was utilized in this qualitative, multisite-designed study. For each of the four participants, three separate site visits were completed. Observations and post-observational interviews took place at each site visit. Transcribed data from interviews, observations, and course documents were imported into the computer program Nvivo8. Repetitive comparative analysis was utilized to complete the data coding process. The guiding research question of this study sought to investigate the implementation strategies of case studies in didactic nursing courses. The implementation of case studies by the participants reflected two primary patterns: Formal Implementation (FI) and Informal Implementation (II) of case studies. The FI of case studies was further divided into two subcategories: Formal Implementation of case studies used Inside the Classroom setting (FIIC) and Formal Implementation of cases studies used Outside of the Classroom (FIOC). Results of this investigation have led to an increased understanding of implementation strategies of unfolding scenario-based case studies in undergraduate nursing didactic courses. Data collected were rich in the description of specific methodologies for utilization of case studies and may serve as a resource for faculty in development of creative strategies to enhance the didactic classroom experience.

Implementation of case studies in undergraduate didactic nursing courses: a qualitative study

PubMed Central

2013-01-01

Background The implementation of unfolding scenario-based case studies in the didactic classroom is associated with learner-centered education. The utilization of learner-centered pedagogies, such as case studies, removes the focus from the instructor and instead places it on the student. Learner-centered pedagogies are believed to improve students’ levels of cognition. The purpose of this study was to examine how nurse educators are implementing the pedagogies of case studies in their undergraduate didactic courses. The goal was to examine, document, report, and, ultimately, implement the strategies. Methods Purposeful sampling was utilized in this qualitative, multisite-designed study. For each of the four participants, three separate site visits were completed. Observations and post-observational interviews took place at each site visit. Transcribed data from interviews, observations, and course documents were imported into the computer program Nvivo8. Repetitive comparative analysis was utilized to complete the data coding process. Results The guiding research question of this study sought to investigate the implementation strategies of case studies in didactic nursing courses. The implementation of case studies by the participants reflected two primary patterns: Formal Implementation (FI) and Informal Implementation (II) of case studies. The FI of case studies was further divided into two subcategories: Formal Implementation of case studies used Inside the Classroom setting (FIIC) and Formal Implementation of cases studies used Outside of the Classroom (FIOC). Conclusion Results of this investigation have led to an increased understanding of implementation strategies of unfolding scenario-based case studies in undergraduate nursing didactic courses. Data collected were rich in the description of specific methodologies for utilization of case studies and may serve as a resource for faculty in development of creative strategies to enhance the didactic classroom experience. PMID:23826925

The Use of Case Studies in Teaching Undergraduate Neuroscience

PubMed Central

Meil, William M.

2007-01-01

Case studies have been the cornerstone of many discoveries in neurology and continue to be an indispensable source of knowledge. Attaching a name, face, and story to the study of neurological disorders makes them more “real” and memorable. This article describes the value of the case study methodology and its advantages as a pedagogical approach. It also illustrates how the seminal case of H.M. can be used to highlight the advantages and disadvantages of the case study methodology. Three exercises are described for incorporating case studies into neuroscience courses. The first exercise requires students to conduct a literature review regarding their assigned case and then design an experiment to address a lingering question regarding that neurological disorder. Survey results of 90 students provide quantitative and qualitative support for this approach. The vast majority of students indicated this exercise was a valuable learning experience; sparked interest in the topic and in biopsychology; increased their knowledge and stimulated critical thinking. The second exercise discusses how students might conduct their own case studies. The third exercise emphasizes the use of case studies as a platform to examine competing hypotheses regarding neurological conditions and their treatment. A table listing case studies appropriate for undergraduate neuroscience courses is included. Cases are categorized by the type of neurological disorder and notes regarding the nature of and content of each case are provided. PMID:23493154

Abu Sayyaf Group (ASG): An Al-Qaeda Associate Case Study

DTIC Science & Technology

2017-10-01

completed in August 2017. In order to conduct this assessment, CNA used a comparative methodology that included eight case studies on groups affiliated...assessment, CNA used a comparative methodology that included eight case studies on groups affiliated or associated with Al-Qaeda. These case studies ...Case Study P. Kathleen Hammerberg and Pamela G. Faber With contributions from Alexander Powell October 2017 This work was performed

OD in Schools: The State of the Art. Vol. IV: Case Studies. Final Report.

ERIC Educational Resources Information Center

Fullan, Michael; And Others

This volume, the fourth of a five-volume series, contains three onsite case studies of organization development (OD) selected from a sample of 76 school districts. The purpose of the case studies was to analyze in detail different types of OD programs and their use. Each case study represents a different OD focus: case study A involves a survey…

World Perspective Case Descriptions on Educational Programs for Adults: Cameroon.

ERIC Educational Resources Information Center

Nyemba, J. A.

This document contains two case studies of adult education programs in Cameroon. Both case studies begin with a "face sheet" on which is recorded basic information about the program and the case study itself. One case study is intended to evaluate the impact of the agricultural university center in the Dschang area from 1977-1987 and to…

Turning to Case Studies as a Mechanism for Learning in Action Learning

ERIC Educational Resources Information Center

O'Leary, Denise; Coughlan, Paul; Rigg, Clare; Coghlan, David

2017-01-01

Case studies are a useful means of capturing and sharing experiential knowledge by allowing researchers to explore the social, organisational and political contexts of a specific case. Although accounts of action learning are often reported using a case study approach, it is not common to see individual case studies being used as a learning…

Making a Case for a Blended Approach: The Need for The Design-Based Case Study

ERIC Educational Resources Information Center

Deaton, Cynthia C. M.; Malloy, Jacquelynn A.

2017-01-01

Design-based case studies address research questions that involve instructional innovations within a bounded system. This blend of case study and design-based research provides a systematic approach to examining instructional innovations that are bounded by perspective, context, and time. Design-based case studies provide a framework for engaging…

The Effect of Using Case Studies in Business Statistics

ERIC Educational Resources Information Center

Pariseau, Susan E.; Kezim, Boualem

2007-01-01

The authors evaluated the effect on learning of using case studies in business statistics courses. The authors divided students into 3 groups: a control group, a group that completed 1 case study, and a group that completed 3 case studies. Results evidenced that, on average, students whom the authors required to complete a case analysis received…

CASE STUDY CRITIQUE; UPPER CLINCH CASE STUDY

EPA Science Inventory

Case study critique: Upper Clinch case study (from Research on Methods for Integrating Ecological Economics and Ecological Risk Assessment: A Trade-off Weighted Index Approach to Integrating Economics and Ecological Risk Assessment). This critique answers the questions: 1) does ...

Pathology informatics fellowship retreats: The use of interactive scenarios and case studies as pathology informatics teaching tools.

PubMed

Lee, Roy E; McClintock, David S; Balis, Ulysses J; Baron, Jason M; Becich, Michael J; Beckwith, Bruce A; Brodsky, Victor B; Carter, Alexis B; Dighe, Anand S; Haghighi, Mehrvash; Hipp, Jason D; Henricks, Walter H; Kim, Jiyeon Y; Klepseis, Veronica E; Kuo, Frank C; Lane, William J; Levy, Bruce P; Onozato, Maristela L; Park, Seung L; Sinard, John H; Tuthill, Mark J; Gilbertson, John R

2012-01-01

Last year, our pathology informatics fellowship added informatics-based interactive case studies to its existing educational platform of operational and research rotations, clinical conferences, a common core curriculum with an accompanying didactic course, and national meetings. The structure of the informatics case studies was based on the traditional business school case study format. Three different formats were used, varying in length from short, 15-minute scenarios to more formal multiple hour-long case studies. Case studies were presented over the course of three retreats (Fall 2011, Winter 2012, and Spring 2012) and involved both local and visiting faculty and fellows. Both faculty and fellows found the case studies and the retreats educational, valuable, and enjoyable. From this positive feedback, we plan to incorporate the retreats in future academic years as an educational component of our fellowship program. Interactive case studies appear to be valuable in teaching several aspects of pathology informatics that are difficult to teach in more traditional venues (rotations and didactic class sessions). Case studies have become an important component of our fellowship's educational platform.

[Case-non case studies: Principles, methods, bias and interpretation].

PubMed

Faillie, Jean-Luc

2017-10-31

Case-non case studies belongs to the methods assessing drug safety by analyzing the disproportionality of notifications of adverse drug reactions in pharmacovigilance databases. Used for the first time in the 1980s, the last few decades have seen a significant increase in the use of this design. The principle of the case-non case study is to compare drug exposure in cases of a studied adverse reaction with that of cases of other reported adverse reactions and called "non cases". Results are presented in the form of a reporting odds ratio (ROR), the interpretation of which makes it possible to identify drug safety signals. This article describes the principle of the case-non case study, the method of calculating the ROR and its confidence interval, the different modalities of analysis and how to interpret its results with regard to the advantages and limitations of this design. Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

Environmental Technology Verification (ETV) Program Case Studies: Demonstrating Program Outcomes, Volume III

EPA Science Inventory

This booklet, ETV Program Case Studies: Demonstrating Program Outcomes, Volume III contains two case studies, addressing verified environmental technologies for decentalized wastewater treatment and converting animal waste to energy. Each case study contains a brief description ...

Joint Forces Command - Operation United Assistance Case Study: Lessons and Best Practices

DTIC Science & Technology

2016-07-01

additional and prioritized computers and access in the operations center for these mission requirements are essential. 127 JFC-OUA CASE STUDY Issue...this publication is welcomed and highly encouraged. Joint Forces Command – Operation United Assistance Case Study JFC-OUA CASE STUDY iii Foreword...Based on information drawn from various sources including after action reports, lessons learned, case studies , umbrella-week visits, and key-leader

Case Study Teaching

ERIC Educational Resources Information Center

Herreid, Clyde Freeman

2011-01-01

This chapter describes the history of case study teaching, types of cases, and experimental data supporting their effectiveness. It also describes a model for comparing the efficacy of the various case study methods. (Contains 1 figure.)

Characteristics, extent and origin of hydrothermal alteration at Mount Rainier Volcano, Cascades Arc, USA: Implications for debris-flow hazards and mineral deposits

USGS Publications Warehouse

John, D.A.; Sisson, T.W.; Breit, G.N.; Rye, R.O.; Vallance, J.W.

2008-01-01

Hydrothermal alteration at Mount Rainier waxed and waned over the 500,000-year episodic growth of the edifice. Hydrothermal minerals and their stable-isotope compositions in samples collected from outcrop and as clasts from Holocene debris-flow deposits identify three distinct hypogene argillic/advanced argillic hydrothermal environments: magmatic-hydrothermal, steam-heated, and magmatic steam (fumarolic), with minor superimposed supergene alteration. The 3.8??km3 Osceola Mudflow (5600??y BP) and coeval phreatomagmatic F tephra contain the highest temperature and most deeply formed hydrothermal minerals. Relatively deeply formed magmatic-hydrothermal alteration minerals and associations in clasts include quartz (residual silica), quartz-alunite, quartz-topaz, quartz-pyrophyllite, quartz-dickite/kaolinite, and quartz-illite (all with pyrite). Clasts of smectite-pyrite and steam-heated opal-alunite-kaolinite are also common in the Osceola Mudflow. In contrast, the Paradise lahar, formed by collapse of the summit or near-summit of the edifice at about the same time, contains only smectite-pyrite and near-surface steam-heated and fumarolic alteration minerals. Younger debris-flow deposits on the west side of the volcano (Round Pass and distal Electron Mudflows) contain only low-temperature smectite-pyrite assemblages, whereas the proximal Electron Mudflow and a < 100??y BP rock avalanche on Tahoma Glacier also contain magmatic-hydrothermal alteration minerals that are exposed in the avalanche headwall of Sunset Amphitheater, reflecting progressive incision into deeper near-conduit alteration products that formed at higher temperatures. The pre-Osceola Mudflow alteration geometry is inferred to have consisted of a narrow feeder zone of intense magmatic-hydrothermal alteration limited to near the conduit of the volcano, which graded outward to more widely distributed, but weak, smectite-pyrite alteration within 1??km of the edifice axis, developed chiefly in porous breccias. The edifice was capped by a steam-heated alteration zone, most of which resulted from condensation of fumarolic vapor and oxidation of H2S in the unsaturated zone above the water table. Weakly developed smectite-pyrite alteration extended into the west and east flanks of the edifice, spatially associated with dikes that are localized in those sectors; other edifice flanks lack dikes and associated alteration. The Osceola collapse removed most of the altered core and upper east flank of the volcano, but intensely altered rocks remain on the uppermost west flank. Major conclusions of this study are that: (1) Hydrothermal-mineral assemblages and distributions at Mount Rainier can be understood in the framework of hydrothermal processes and environments developed from studies of ore deposits formed in analogous settings. (2) Frequent eruptions supplied sufficient hot magmatic fluid to alter the upper interior of the volcano hydrothermally, despite the consistently deep (??? 8??km) magma reservoir which may have precluded formation of economic mineral deposits within or at shallow depths beneath Mount Rainier. The absence of indicator equilibrium alteration-mineral assemblages in the debris flows that effectively expose the volcano to a depth of 1-1.5??km also suggests a low potential for significant high-sulfidation epithermal or porphyry-type mineral deposits at depth. (3) Despite the long and complex history of the volcano, intensely altered collapse-prone rocks were spatially restricted to near the volcano's conduit system and summit, and short distances onto the upper east and west flanks, due to the necessary supply of reactive components carried by ascending magmatic fluids. (4) Intensely altered rocks were removed from the summit, east flank, and edifice interior by the Osceola collapse, but remain on the upper west flank in the Sunset Amphitheater area and present a continuing collapse hazard. (5) Visually conspicuous rocks on the lower east and mid-to-lower

Case Studies for School Administrators: Managing Change in Education.

ERIC Educational Resources Information Center

Benham, Maenette K. P. Ah Nee

This book examines case-based learning in educational leadership courses, discusses case-based learning as an educational tool, exemplifies methods of writing a case study, and contains 14 case-studies by teachers and administrators. "Stakeholders in a House of Cards," by Audrey Burgher, discusses integrating technology with innovation.…

How To Set Up Your Own Small Business. Service Company Case Study. Manufacturing Firm Case Study. Retail Store Case Study.

ERIC Educational Resources Information Center

Fallek, Max

This collection of case studies is intended for use in a course in setting up a small business. The first, a case study of the process of setting up a service company, covers analyzing the pros and cons of starting one's own business, assessing the competition and local market, and selecting a site for and financing the business. The principal…

[The case-case-time-control study design].

PubMed

Wang, Jing; Zhuo, Lin; Zhan, Siyan

2014-12-01

Although the 'self-matched case-only studies' (such as the case-cross-over or self-controlled case-series method) can control the time-invariant confounders (measured or unmeasured) through design of the study, however, they can not control those confounders that vary with time. A bidirectional case-crossover design can be used to adjust the exposure-time trends. In the areas of pharmaco-epidemiology, illness often influence the future use of medications, making a bidirectional study design problematic. Suissa's case-time-control design combines the case-crossover and the case-control design which could adjust for exposure-trend bias, but the control group may reintroduce selection bias, if the matching does not go well. We propose a "case-case-time-control" design which is an extension of the case-time-control design. However, rather than using a sample of external controls, we choose those future cases as controls for current cases to counter the bias that arising from temporal trends caused by exposure to the target of interest. In the end of this article we will discuss the strength and limitations of this design based on an applied example.

Real-Life Case Studies for Teachers.

ERIC Educational Resources Information Center

Hayes, William

Case studies described in this book reflect conditions present in today's public schools. Situations described in these case studies are intended to introduce education students to the variety of problems existing in today's schools. The 38 case studies highlight: student cheating; teacher's observation by administrator; inclusion; contract…

The Case Study as Research Heuristic: Lessons from the R&D Value Mapping Project.

ERIC Educational Resources Information Center

Bozeman, Barry; Klein, Hans K.

1999-01-01

Examines the role of prototype case studies as the foundation for later evaluation through two studies from the "R&D Value Mapping Project," a study that will involve more than 30 cases. Explores the usefulness of case studies in defining and assessing subsequent research efforts. (SLD)

A Careful Look at Modern Case Selection Methods

ERIC Educational Resources Information Center

Herron, Michael C.; Quinn, Kevin M.

2016-01-01

Case studies appear prominently in political science, sociology, and other social science fields. A scholar employing a case study research design in an effort to estimate causal effects must confront the question, how should cases be selected for analysis? This question is important because the results derived from a case study research program…

Case-control studies in neurosurgery.

PubMed

Nesvick, Cody L; Thompson, Clinton J; Boop, Frederick A; Klimo, Paul

2014-08-01

Observational studies, such as cohort and case-control studies, are valuable instruments in evidence-based medicine. Case-control studies, in particular, are becoming increasingly popular in the neurosurgical literature due to their low cost and relative ease of execution; however, no one has yet systematically assessed these types of studies for quality in methodology and reporting. The authors performed a literature search using PubMed/MEDLINE to identify all studies that explicitly identified themselves as "case-control" and were published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Each paper was evaluated for 22 descriptive variables and then categorized as having either met or missed the basic definition of a case-control study. All studies that evaluated risk factors for a well-defined outcome were considered true case-control studies. The authors sought to identify key features or phrases that were or were not predictive of a true case-control study. Those papers that satisfied the definition were further evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. The search detected 67 papers that met the inclusion criteria, of which 32 (48%) represented true case-control studies. The frequency of true case-control studies has not changed with time. Use of odds ratios (ORs) and logistic regression (LR) analysis were strong positive predictors of true case-control studies (for odds ratios, OR 15.33 and 95% CI 4.52-51.97; for logistic regression analysis, OR 8.77 and 95% CI 2.69-28.56). Conversely, negative predictors included focus on a procedure/intervention (OR 0.35, 95% CI 0.13-0.998) and use of the word "outcome" in the Results section (OR 0.23, 95% CI 0.082-0.65). After exclusion of nested case-control studies, the negative correlation between focus on a procedure/intervention and true case-control studies was strengthened (OR 0.053, 95% CI 0.0064-0.44). There was a trend toward a negative association between the use of survival analysis or Kaplan-Meier curves and true case-control studies (OR 0.13, 95% CI 0.015-1.12). True case-control studies were no more likely than their counterparts to use a potential study design "expert" (OR 1.50, 95% CI 0.57-3.95). The overall average STROBE score was 72% (range 50-86%). Examples of reporting deficiencies were reporting of bias (28%), missing data (55%), and funding (44%). The results of this analysis show that the majority of studies in the neurosurgical literature that identify themselves as "case-control" studies are, in fact, labeled incorrectly. Positive and negative predictors were identified. The authors provide several recommendations that may reverse the incorrect and inappropriate use of the term "case-control" and improve the quality of design and reporting of true case-control studies in neurosurgery.

Methodology Series Module 2: Case-control Studies.

PubMed

Setia, Maninder Singh

2016-01-01

Case-Control study design is a type of observational study. In this design, participants are selected for the study based on their outcome status. Thus, some participants have the outcome of interest (referred to as cases), whereas others do not have the outcome of interest (referred to as controls). The investigator then assesses the exposure in both these groups. The investigator should define the cases as specifically as possible. Sometimes, definition of a disease may be based on multiple criteria; thus, all these points should be explicitly stated in case definition. An important aspect of selecting a control is that they should be from the same 'study base' as that of the cases. We can select controls from a variety of groups. Some of them are: General population; relatives or friends; and hospital patients. Matching is often used in case-control control studies to ensure that the cases and controls are similar in certain characteristics, and it is a useful technique to increase the efficiency of the study. Case-Control studies can usually be conducted relatively faster and are inexpensive - particularly when compared with cohort studies (prospective). It is useful to study rare outcomes and outcomes with long latent periods. This design is not very useful to study rare exposures. Furthermore, they may also be prone to certain biases - selection bias and recall bias.

Arsenic Removal - Adsorptive Media and Coagulation/Filtration Case Studies - Slides

EPA Science Inventory

This presentation provides information on the results of three case studies from USEPA arsenic demonstration program. The first case study presented is on the Rimrock, AZ project that used an adsorptive media technology (E33 media) to remove arsenic. The second case study is o...

Arsenic Removal: Adsorptive Media and Coagulation/Filtration Case Studies

EPA Science Inventory

This presentation provides information on the results of three case studies from USEPA arsenic demonstration program. The first case study presented is on the Rimrock, AZ project that used an adsorptive media technology (E33 media) to remove arsenic. The second case study is on...

Putting Words in Their Mouth: Writing Dialogue for Case Studies

ERIC Educational Resources Information Center

Herreid, Clyde Freeman

2018-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This issue discusses dialogue writing guidelines most relevant to case writing.

Comparison of Estimates between Cohort and Case-Control Studies in Meta-Analyses of Therapeutic Interventions: A Meta-Epidemiological Study.

PubMed

Lanza, Amy; Ravaud, Philippe; Riveros, Carolina; Dechartres, Agnes

2016-01-01

Observational studies are increasingly being used for assessing therapeutic interventions. Case-control studies are generally considered to have greater risk of bias than cohort studies, but we lack evidence of differences in effect estimates between the 2 study types. We aimed to compare estimates between cohort and case-control studies in meta-analyses of observational studies of therapeutic interventions by using a meta-epidemiological study. We used a random sample of meta-analyses of therapeutic interventions published in 2013 that included both cohort and case-control studies assessing a binary outcome. For each meta-analysis, the ratio of estimates (RE) was calculated by comparing the estimate in case-control studies to that in cohort studies. Then, we used random-effects meta-analysis to estimate a combined RE across meta-analyses. An RE < 1 indicated that case-control studies yielded larger estimates than cohort studies. The final analysis included 23 meta-analyses: 138 cohort and 133 case-control studies. Treatment effect estimates did not significantly differ between case-control and cohort studies (combined RE 0.97 [95% CI 0.86-1.09]). Heterogeneity was low, with between-meta-analysis variance τ2 = 0.0049. Estimates did not differ between case-control and prospective or retrospective cohort studies (RE = 1.05 [95% CI 0.96-1.15] and RE = 0.99 [95% CI, 0.83-1.19], respectively). Sensitivity analysis of studies reporting adjusted estimates also revealed no significant difference (RE = 1.03 [95% CI 0.91-1.16]). Heterogeneity was also low for these analyses. We found no significant difference in treatment effect estimates between case-control and cohort studies assessing therapeutic interventions.

Global dengue death before and after the new World Health Organization 2009 case classification: A systematic review and meta-regression analysis.

PubMed

Low, Gary Kim-Kuan; Ogston, Simon A; Yong, Mun-Hin; Gan, Seng-Chiew; Chee, Hui-Yee

2018-06-01

Since the introduction of 2009 WHO dengue case classification, no literature was found regarding its effect on dengue death. This study was to evaluate the effect of 2009 WHO dengue case classification towards dengue case fatality rate. Various databases were used to search relevant articles since 1995. Studies included were cohort and cross-sectional studies, all patients with dengue infection and must report the number of death or case fatality rate. The Joanna Briggs Institute appraisal checklist was used to evaluate the risk of bias of the full-texts. The studies were grouped according to the classification adopted: WHO 1997 and WHO 2009. Meta-regression was employed using a logistic transformation (log-odds) of the case fatality rate. The result of the meta-regression was the adjusted case fatality rate and odds ratio on the explanatory variables. A total of 77 studies were included in the meta-regression analysis. The case fatality rate for all studies combined was 1.14% with 95% confidence interval (CI) of 0.82-1.58%. The combined (unadjusted) case fatality rate for 69 studies which adopted WHO 1997 dengue case classification was 1.09% with 95% CI of 0.77-1.55%; and for eight studies with WHO 2009 was 1.62% with 95% CI of 0.64-4.02%. The unadjusted and adjusted odds ratio of case fatality using WHO 2009 dengue case classification was 1.49 (95% CI: 0.52, 4.24) and 0.83 (95% CI: 0.26, 2.63) respectively, compared to WHO 1997 dengue case classification. There was an apparent increase in trend of case fatality rate from the year 1992-2016. Neither was statistically significant. The WHO 2009 dengue case classification might have no effect towards the case fatality rate although the adjusted results indicated a lower case fatality rate. Future studies are required for an update in the meta-regression analysis to confirm the findings. Copyright © 2018 Elsevier B.V. All rights reserved.

Business and Consumer Education Case Studies.

ERIC Educational Resources Information Center

Delta Pi Epsilon, Minneapolis, Minn. Phi Chapter.

This publication contains 58 case studies for classroom use in teaching various business and consumer education subjects at the high school level. A supplement to a previous Phi Chapter publication, "Office Education Case Studies" (1973), the case studies are intended to create class discussions and help students acquire the ability to analyze…

75 FR 11183 - Proposed Data Collections Submitted for Public Comment and Recommendations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-10

... technology. Written comments should be received within 60 days of this notice. Proposed Project Case Studies... case studies of six CPPW-funded states and 15 CPPW-funded communities. The case study sites will be... region, and targeted population. Case study information will be collected by conducting personal...

75 FR 51806 - Climate Change Vulnerability Assessment: Four Case Studies of Water Utility Practices

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-23

... case studies describing the approaches currently being taken by four water utilities to assess their... series of case studies describing the approaches currently being taken by four water utilities in the... Vulnerability Assessment: Four Case Studies of Water Utility Practices AGENCY: Environmental Protection Agency...

Natural Learning Case Study Archives

ERIC Educational Resources Information Center

Lawler, Robert W.

2015-01-01

Natural Learning Case Study Archives (NLCSA) is a research facility for those interested in using case study analysis to deepen their understanding of common sense knowledge and natural learning (how the mind interacts with everyday experiences to develop common sense knowledge). The database comprises three case study corpora based on experiences…

Paradise nearly Gained. Volume 2: Case Studies of Impact and Diversity for Frontline Management Initiative Practice.

ERIC Educational Resources Information Center

Barratt-Pugh, Llandis; Soutar, Geoffrey N.

This document presents the case studies from a multi-phase study of the impact of Australia's Frontline Management Initiative (FMI), which provides a framework for competency-based development of frontline managers in Australian enterprises. Nineteen organizational case studies and one individual case study of the FMI's impacts are included. The…

Developing and pretesting case studies in dental and dental hygiene education: using the diffusion of innovations model.

PubMed

Cragun, Deborah L; DeBate, Rita DiGioacchino; Severson, Herbert H; Shaw, Tracy; Christiansen, Steve; Koerber, Anne; Tomar, Scott L; Brown, Kelli McCormack; Tedesco, Lisa A; Hendricson, William D

2012-05-01

Case-based learning offers exposure to clinical situations that health professions students may not encounter in their training. The purposes of this study were to apply the Diffusion of Innovations conceptual framework to 1) identify characteristics of case studies that would increase their adoption among dental and dental hygiene faculty members and 2) develop and pretest interactive web-based case studies on sensitive oral-systemic health issues. The formative study spanned two phases using mixed methods (Phase 1: eight focus groups and four interviews; Phase 2: ten interviews and satisfaction surveys). Triangulation of quantitative and qualitative data revealed the following positive attributes of the developed case studies: relative advantage of active learning and modeling; compatibility with a variety of courses; observability of case-related knowledge and skills; independent learning; and modifiability for use with other oral-systemic health issues. These positive attributes are expected to increase the likelihood that dental and dental hygiene faculty members will adopt the developed case study once it is available for use. The themes identified in this study could be applied to the development of future case studies and may provide broader insight that might prove useful for exploring differences in case study use across dental and dental hygiene curricula.

Case Study: What Makes a Good Case, Revisited: The Survey Monkey Tells All

ERIC Educational Resources Information Center

Herried, Clyde Freeman; Prud'homme-Genereux, Annie; Schiller, Nancy A.; Herreid, Ky F.; Wright, Carolyn

2016-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. In this month's issue the authors provide a more definitive answer to the "What Makes a Good Case?" question based on a just-completed Survey Monkey survey given to NCCSTS teachers.

Theoretical pluralism in psychoanalytic case studies.

PubMed

Willemsen, Jochem; Cornelis, Shana; Geerardyn, Filip M; Desmet, Mattias; Meganck, Reitske; Inslegers, Ruth; Cauwe, Joachim M B D

2015-01-01

The aim of this study is to provide an overview of the scientific activity of different psychoanalytic schools of thought in terms of the content and production of case studies published on ISI Web of Knowledge. Between March 2013 and November 2013, we contacted all case study authors included in the online archive of psychoanalytic and psychodynamic case studies (www.singlecasearchive.com) to inquire about their psychoanalytic orientation during their work with the patient. The response rate for this study was 45%. It appears that the two oldest psychoanalytic schools, Object-relations psychoanalysis and Ego psychology or "Classical psychoanalysis" dominate the literature of published case studies. However, most authors stated that they feel attached to two or more psychoanalytic schools of thought. This confirms that the theoretical pluralism in psychoanalysis stretches to the field of single case studies. The single case studies of each psychoanalytic school are described separately in terms of methodology, patient, therapist, or treatment features. We conclude that published case studies features are fairly similar across different psychoanalytic schools. The results of this study are not representative of all psychoanalytic schools, as some do not publish their work in ISI ranked journals.

Theoretical pluralism in psychoanalytic case studies

PubMed Central

Willemsen, Jochem; Cornelis, Shana; Geerardyn, Filip M.; Desmet, Mattias; Meganck, Reitske; Inslegers, Ruth; Cauwe, Joachim M. B. D.

2015-01-01

The aim of this study is to provide an overview of the scientific activity of different psychoanalytic schools of thought in terms of the content and production of case studies published on ISI Web of Knowledge. Between March 2013 and November 2013, we contacted all case study authors included in the online archive of psychoanalytic and psychodynamic case studies (www.singlecasearchive.com) to inquire about their psychoanalytic orientation during their work with the patient. The response rate for this study was 45%. It appears that the two oldest psychoanalytic schools, Object-relations psychoanalysis and Ego psychology or “Classical psychoanalysis” dominate the literature of published case studies. However, most authors stated that they feel attached to two or more psychoanalytic schools of thought. This confirms that the theoretical pluralism in psychoanalysis stretches to the field of single case studies. The single case studies of each psychoanalytic school are described separately in terms of methodology, patient, therapist, or treatment features. We conclude that published case studies features are fairly similar across different psychoanalytic schools. The results of this study are not representative of all psychoanalytic schools, as some do not publish their work in ISI ranked journals. PMID:26483725

[A clinical study of PC-904 in pediatrics (author's transl)].

PubMed

Hori, M; Kono, S; Hashimoto, F

1978-07-01

A clinical study of PC-904 was performed in children. The results were as follows; 1) Serum levels of PC-904 after single administration of 20 mg/kg were studied in patients by one-shot intravenous injection or drip infusion for 1 hour or 2 hours. The results obtained in this fundamental study led to the suggestion that the proper dosage in bacterial infections would be 50 approximately 100 mg/kg intravenously in 3 approximately 4 divided doses daily. 2) A clinical study of PC-904 was performed in 16 patients including acute pharyngitis and bronchitis (3 cases), acute bronchopneumonia (3 cases), pertussis pneumonia (1 case), lymphadenitis purulenta (2 cases), acute bronchopneumonia (3 cases), pertussis pneumonia (1 case), lymphadenitis purulenta (2 cases), abscess with chronic granuloma (2 cases) and urinary tract infection (5 cases). About 50 approximately 100 mg/kg of PC-904 were administered in 3 approximately 4 divided doses daily by one-shot intravenous injection. The clinical effects of 2 cases out of 16 were impossible to be evaluated, and thses cases were excluded from the clinical evaluation. Ten cases out of 14 showed excellent or good responses (efficacy rate: 71.4%). 3) The bacteriological examinations were performed and the causative or isolated organisms were determined in 11 cases. The responses were "disappeared" in 6 cases, "decreased" in 2 cases and "not disappeared" in 3 cases. 4) No side effects were observed. Abnormalities of laboratory findings were not also noticed.

Pathology analysis for mesothelioma study in the United Kingdom: Current practice and historical development.

PubMed

Case, B W

2016-01-01

Following up on the largest case-control study of malignant mesothelioma yet performed, investigators at the London School of Hygiene and Tropical Medicine assessed 1732 male and 670 female cases as of May 2013. Epidemiological findings of a subset of these were published previously, excluding patients who died or who refused to be interviewed. Pathology reports were collected for subjects, including those both eligible and ineligible for epidemiology study based on vital status. The current investigation examined 860 cases having pathology reports available. Sixty-one cases were diagnosed using cytology only, often with equivocal diagnoses, while 799 reported at least a biopsy of the tumor. Of these, 748 had pathology sufficiently detailed for evaluation. These reports were examined for basis of diagnosis, differences between study cases and ineligible cases, pathology characteristics, and immunohistochemical and other tests used. The most prominent subtype was epithelioid (64% of study cases but only 49% of ineligible cases). Biphasic subtype was present in 10% of study cases and 16% of those ineligible. Sarcomatoid subtype was present in 7% of study cases and 19% of ineligible cases, most of whom died. Twelve percent of study cases displayed no specified subtype, versus 7% of ineligible cases. Of recorded immunohistochemical stains specific for mesothelial cell origin, calretinin (95%) and CK 5/6 or CK5 alone (84%) were by far the most common. Calretinin and CK 5/6 or CK 5 alone were also most sensitive and positive in 92% of cases presenting with surgical pathology report. Ninety percent of cases had at least one immunohistochemical marker for possible lung carcinoma applied, with BER-Ep4 and TTF-1 the most frequent at 68% and CEA at 58%. TTF-1 and CEA were positive in 1% or less of cases. Patterns of use and positive and negative results for each of these as well as other immunohistochemical stains are presented and discussed, along with a brief historical description of their development and use. Possible effects of the pathologic analysis on the results of previously published and future epidemiological studies are discussed.

CRIS Case Study Materials in Ethical Decision Making.

ERIC Educational Resources Information Center

Blanning, James R.

Designed for secondary-level classroom discussion, these materials contain nine, short case studies of ethical dilemmas. The cast studies focus mainly on incidents and issues relevant to high school students. Discussion questions for each case study require students to examine the case, discuss the issue, and make an ethical decision about how…

Case Study: The Chemistry of Cocaine

ERIC Educational Resources Information Center

Dewprashad, Brahmadeo

2011-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's case study focuses on the chemistry of cocaine to teach a number of core concepts in organic chemistry. It also requires that students read and analyze an original research paper on…

Interpretive Research Aiming at Theory Building: Adopting and Adapting the Case Study Design

ERIC Educational Resources Information Center

Diaz Andrade, Antonio

2009-01-01

Although the advantages of case study design are widely recognised, its original positivist underlying assumptions may mislead interpretive researchers aiming at theory building. The paper discusses the limitations of the case study design for theory building and explains how grounded theory systemic process adds to the case study design. The…

Using Case Studies in the Introductory Public Relations Course.

ERIC Educational Resources Information Center

Adams, William C.

The case study method has received increased attention at both the graduate and undergraduate levels in a number of public relations programs. Unlike the Harvard managerial-oriented case studies, the approach useful in large, introductory public relations courses stems from a simplified team approach to classroom projects, case studies in the…

Peace Corps Water/Sanitation Case Studies and Analyses. Appropriate Technologies for Development. Case Study CS-4.

ERIC Educational Resources Information Center

Talbert, Diana E., Comp.

This document provides an overview of Peace Corps water and sanitation activities, five case studies (Thailand, Yemen, Paraguay, Sierra Leone, and Togo), programming guidelines, and training information. Each case study includes: (1) background information on the country's geography, population, and economics; (2) information on the country's…

Role of matching in case-control studies of antimicrobial resistance.

PubMed

Cerceo, Elizabeth; Lautenbach, Ebbing; Linkin, Darren R; Bilker, Warren B; Lee, Ingi

2009-05-01

Of 57 case-control studies of antimicrobial resistance, matching was used in 23 (40%). Matched variables differed substantially across studies. Of these 23 matched case-control studies, 12 (52%) justified the use of matching, and 9 (39%) noted the strengths or limitations of this approach. Analysis that accounted for matching was performed in only 52% of the case-control studies.

Evaluating Creative Thinking of Rn-Bsn Students in the Course of Clinical Case Study and Practicum

ERIC Educational Resources Information Center

Ku, Ya-Lie

2015-01-01

This case study evaluated creative thinking of RN-BSN students in the course of clinical case study and practicum. Study design used quantitative and qualitative evaluations of creative thinking of RN-BSN students by triangulation method in the course of clinical case study and practicum. Sixty RN-BSN students self-perceived the changing levels of…

Schematic representation of case study research designs.

PubMed

Rosenberg, John P; Yates, Patsy M

2007-11-01

The paper is a report of a study to demonstrate how the use of schematics can provide procedural clarity and promote rigour in the conduct of case study research. Case study research is a methodologically flexible approach to research design that focuses on a particular case - whether an individual, a collective or a phenomenon of interest. It is known as the 'study of the particular' for its thorough investigation of particular, real-life situations and is gaining increased attention in nursing and social research. However, the methodological flexibility it offers can leave the novice researcher uncertain of suitable procedural steps required to ensure methodological rigour. This article provides a real example of a case study research design that utilizes schematic representation drawn from a doctoral study of the integration of health promotion principles and practices into a palliative care organization. The issues discussed are: (1) the definition and application of case study research design; (2) the application of schematics in research; (3) the procedural steps and their contribution to the maintenance of rigour; and (4) the benefits and risks of schematics in case study research. The inclusion of visual representations of design with accompanying explanatory text is recommended in reporting case study research methods.

Case Reports, Case Series - From Clinical Practice to Evidence-Based Medicine in Graduate Medical Education.

PubMed

Sayre, Jerry W; Toklu, Hale Z; Ye, Fan; Mazza, Joseph; Yale, Steven

2017-08-07

Case reports and case series or case study research are descriptive studies that are prepared for illustrating novel, unusual, or atypical features identified in patients in medical practice, and they potentially generate new research questions. They are empirical inquiries or investigations of a patient or a group of patients in a natural, real-world clinical setting. Case study research is a method that focuses on the contextual analysis of a number of events or conditions and their relationships. There is disagreement among physicians on the value of case studies in the medical literature, particularly for educators focused on teaching evidence-based medicine (EBM) for student learners in graduate medical education. Despite their limitations, case study research is a beneficial tool and learning experience in graduate medical education and among novice researchers. The preparation and presentation of case studies can help students and graduate medical education programs evaluate and apply the six American College of Graduate Medical Education (ACGME) competencies in the areas of medical knowledge, patient care, practice-based learning, professionalism, systems-based practice, and communication. A goal in graduate medical education should be to assist residents to expand their critical thinking, problem-solving, and decision-making skills. These attributes are required in the teaching and practice of EBM. In this aspect, case studies provide a platform for developing clinical skills and problem-based learning methods. Hence, graduate medical education programs should encourage, assist, and support residents in the publication of clinical case studies; and clinical teachers should encourage graduate students to publish case reports during their graduate medical education.

Methodology Series Module 2: Case-control Studies

PubMed Central

Setia, Maninder Singh

2016-01-01

Case-Control study design is a type of observational study. In this design, participants are selected for the study based on their outcome status. Thus, some participants have the outcome of interest (referred to as cases), whereas others do not have the outcome of interest (referred to as controls). The investigator then assesses the exposure in both these groups. The investigator should define the cases as specifically as possible. Sometimes, definition of a disease may be based on multiple criteria; thus, all these points should be explicitly stated in case definition. An important aspect of selecting a control is that they should be from the same ‘study base’ as that of the cases. We can select controls from a variety of groups. Some of them are: General population; relatives or friends; and hospital patients. Matching is often used in case-control control studies to ensure that the cases and controls are similar in certain characteristics, and it is a useful technique to increase the efficiency of the study. Case-Control studies can usually be conducted relatively faster and are inexpensive – particularly when compared with cohort studies (prospective). It is useful to study rare outcomes and outcomes with long latent periods. This design is not very useful to study rare exposures. Furthermore, they may also be prone to certain biases – selection bias and recall bias. PMID:27057012

Case-Control Studies of Sporadic Enteric Infections: A Review and Discussion of Studies Conducted Internationally from 1990 to 2009

PubMed Central

Fullerton, Kathleen E.; Scallan, Elaine; Kirk, Martyn D.; Mahon, Barbara E.; Angulo, Frederick J.; de Valk, Henriette; van Pelt, Wilfrid; Gauci, Charmaine; Hauri, Anja M.; Majowicz, Shannon; O’Brien, Sarah J.

2015-01-01

Epidemiologists have used case-control studies to investigate enteric disease outbreaks for many decades. Increasingly, case-control studies are also used to investigate risk factors for sporadic (not outbreak-associated) disease. While the same basic approach is used, there are important differences between outbreak and sporadic disease settings that need to be considered in the design and implementation of the case-control study for sporadic disease. Through the International Collaboration on Enteric Disease “Burden of Illness” Studies (the International Collaboration), we reviewed 79 case-control studies of sporadic enteric infections caused by nine pathogens that were conducted in 22 countries and published from 1990 through to 2009. We highlight important methodological and study design issues (including case definition, control selection, and exposure assessment) and discuss how approaches to the study of sporadic enteric disease have changed over the last 20 years (e.g., making use of more sensitive case definitions, databases of controls, and computer-assisted interviewing). As our understanding of sporadic enteric infections grows, methods and topics for case-control studies are expected to continue to evolve; for example, advances in understanding of the role of immunity can be used to improve control selection, the apparent protective effects of certain foods can be further explored, and case-control studies can be used to provide population-based measures of the burden of disease. PMID:22443481

Case studies in pathophysiology: The development and evaluation of an interactive online learning environment to develop higher order thinking and argumentation

NASA Astrophysics Data System (ADS)

Titterington, Lynda C.

2007-12-01

This study presents a framework for examining the effects of higher order thinking on the achievement of allied health students enrolled in a pathophysiology course. A series of clinical case studies was developed and published in an enriched online environment that guided students through the process of developing a solution and supporting it through data analysis and interpretation. The series of case study modules scaffolded argumentation through question prompts. The modules began with a simple, direct problem and they became progressively more complex throughout the quarter. A control group was assigned a pencil-and-paper case study based upon recall. The case studies were scored for content accuracy and evidence of higher order thinking skills. Higher order thinking was measured using a rubric based upon the Toulmin argumentation pattern. The results indicated implementing a case study of either online or traditional format was associated with significant gains in achievement. The Web-enhanced case studies were associated with modest gains in knowledge acquisition. The argumentation scores across the series followed two trends: directed case studies were associated with higher levels of argumentation than ill-structured case studies, and there appeared to be an inverse relationship between the students' argumentation and content scores. The protocols developed for this study can serve as a template for a larger, extended investigation into student learning in the online environment.

[Clinical decision making: Fostering critical thinking in the nursing diagnostic process through case studies].

PubMed

Müller-Staub, Maria; Stuker-Studer, Ursula

2006-10-01

Case studies, based on actual patients' situations, provide a method of clinical decision making to foster critical thinking in nurses. This paper describes the method and process of group case studies applied in continuous education settings. This method bases on Balints' case supervision and was further developed and combined with the nursing diagnostic process. A case study contains different phases: Pre-phase, selection phase, case delineation and case work. The case provider narratively tells the situation of a patient. This allows the group to analyze and cluster signs and symptoms, to state nursing diagnoses and to derive nursing interventions. Results of the case study are validated by applying the theoretical background and critical appraisal of the case provider. Learning effects of the case studies were evaluated by means of qualitative questionnaires and analyzed according to Mayring. Findings revealed the following categories: a) Patients' problems are perceived in a patient centred way, accurate nursing diagnoses are stated and effective nursing interventions implemented. b) Professional nursing tasks are more purposefully perceived and named more precise. c) Professional nursing relationship, communication and respectful behaviour with patients were perceived in differentiated ways. The theoretical framework is described in the paper "Clinical decision making and critical thinking in the nursing diagnostic process". (Müller-Staub, 2006).

A Review of Case-Based Learning Practices in an Online MBA Program: A Program-Level Case Study

ERIC Educational Resources Information Center

Lee, Seung-hee; Lee, Jieun; Liu, Xiaojing; Bonk, Curt J.; Magjuka, Richard J.

2009-01-01

This study examines how a case-based learning approach was used and facilitated in online business education. Perceptions of students and instructors regarding the practices of case-based learning in online environments are explored in terms of instructional design, facilitation, and technology support. This study finds case-based learning to be a…

In Case You Are Interested: Results of a Survey of Case Study Teachers

ERIC Educational Resources Information Center

Herreid, Clyde Freeman; Schiller, Nancy A.; Herreid, Ky F.; Wright, Carolyn

2011-01-01

Case study teaching had a long tradition in law and business before it made the jump to medical school education in the form of Problem-Based Learning (PBL) in the 1970s. Today, both the University of Delaware's Clearinghouse and the University of Buffalo's National Center for Case Study Teaching in Science (NCCSTS) have hundreds of cases and…

Teaching Business French through Case Studies: Presentation of a Marketing Case.

ERIC Educational Resources Information Center

Federico, Salvatore; Moore, Catherine

The use of case studies as a means for teaching business French is discussed. The approach is advocated because of the realism of case studies, which are based on actual occurrences. Characteristics of a good case are noted: it tells a story, focuses on interest-arousing issues, is set in the past 10 years, permits empathy with the main…

Cases for the Net Generation: An Empirical Examination of Students' Attitude toward Multimedia Case Studies

ERIC Educational Resources Information Center

Sheppard, Michael; Vibert, Conor

2016-01-01

Case studies have been an important tool in business, legal, and medical education for generations of students. Traditional text-based cases tend to be self-contained and structured in such a way as to teach a particular concept. The multimedia cases introduced in this study feature unscripted web-hosted video interviews with business owners and…

Swiss Armed Forces Organizational Level Leader Development: A Qualitative Case Study

DTIC Science & Technology

2017-06-09

chapter, divided in five distinct parts, describes the chosen research methodology , explain why the qualitative case study is appropriate to conduct...research study uses a qualitative methodology by performing a qualitative case study on the organizational level leader’s development process within...develop an in-depth understsanding of the phenomen.”82 Summary This research study uses a qualitative methodology by performing a case study on the

Exchangeability in the case-crossover design

PubMed Central

Mittleman, Murray A; Mostofsky, Elizabeth

2014-01-01

In cohort and case-control studies, confounding that arises as a result of differences in the distribution of determinants of the outcome between exposure groups leading to non-exchangeability are addressed by restriction, matching or with statistical models. In case-only studies, this issue is addressed by comparing each individual with his/herself. Although case-only designs use self-matching and only include individuals who develop the outcome of interest, issues of non-exchangeability are identical to those that arise in traditional case-control and cohort studies. In this review, we describe one type of case-only design, the case-crossover design, and discuss how the concept of exchangeability can be used to understand issues of confounding, carryover effects, period effects and selection bias in case-crossover studies. PMID:24756878

Transportation planning effectiveness: twenty case studies

DOT National Transportation Integrated Search

1977-12-31

This document consists of 20 site-specific case studies of urban area experience with the Technical Study Grant Program of the Urban Mass Transportation Administration (UMTA). The objective of the case studies is to determine how the Technical Study ...

An alternative approach for socio-hydrology: case study research

NASA Astrophysics Data System (ADS)

Mostert, Erik

2018-01-01

Currently the most popular approach in socio hydrology is to develop coupled human-water models. This article proposes an alternative approach, qualitative case study research, involving a systematic review of (1) the human activities affecting the hydrology in the case, (2) the main human actors, and (3) the main factors influencing the actors and their activities. Moreover, this article presents a case study of the Dommel Basin in Belgium and the Netherlands, and compares this with a coupled model of the Kissimmee Basin in Florida. In both basins a pendulum swing from water resources development and control to protection and restoration can be observed. The Dommel case study moreover points to the importance of institutional and financial arrangements, community values, and broader social, economic, and technical developments. These factors are missing from the Kissimmee model. Generally, case studies can result in a more complete understanding of individual cases than coupled models, and if the cases are selected carefully and compared with previous studies, it is possible to generalize on the basis of them. Case studies also offer more levers for management and facilitate interdisciplinary cooperation. Coupled models, on the other hand, can be used to generate possible explanations of past developments and quantitative scenarios for future developments. The article concludes that, given the limited attention they currently get and their potential benefits, case studies deserve more attention in socio-hydrology.

Human exploration mission studies

NASA Technical Reports Server (NTRS)

Cataldo, Robert L.

1989-01-01

The Office of Exploration has established a process whereby all NASA field centers and other NASA Headquarters offices participate in the formulation and analysis of a wide range of mission strategies. These strategies were manifested into specific scenarios or candidate case studies. The case studies provided a systematic approach into analyzing each mission element. First, each case study must address several major themes and rationale including: national pride and international prestige, advancement of scientific knowledge, a catalyst for technology, economic benefits, space enterprise, international cooperation, and education and excellence. Second, the set of candidate case studies are formulated to encompass the technology requirement limits in the life sciences, launch capabilities, space transfer, automation, and robotics in space operations, power, and propulsion. The first set of reference case studies identify three major strategies: human expeditions, science outposts, and evolutionary expansion. During the past year, four case studies were examined to explore these strategies. The expeditionary missions include the Human Expedition to Phobos and Human Expedition to Mars case studies. The Lunar Observatory and Lunar Outpost to Early Mars Evolution case studies examined the later two strategies. This set of case studies established the framework to perform detailed mission analysis and system engineering to define a host of concepts and requirements for various space systems and advanced technologies. The details of each mission are described and, specifically, the results affecting the advanced technologies required to accomplish each mission scenario are presented.

How informative are case studies of spider bites in the medical literature?

PubMed

Stuber, Marielle; Nentwig, Wolfgang

2016-05-01

We analyzed the reliability and information content of 134 medical case studies on spider bites, published in 91 journal articles. Overall, we found that only 22% of these studies fulfilled the criteria for a verified spider bite. This means that the majority of such case studies cannot be attributed to a given spider species and usually not even to a spider. Their scientific value is negligible, moreover, such publications are even dangerous because they suggest incorrect conclusions. Secondly, we found that such case studies usually do not follow an obvious structure and many details on the development of symptoms, therapy and healing process are widely lacking. So even for verified spider bites, the comparability of case studies is limited. We discuss the obvious failure of a reviewing process for case studies and give recommendations how to increase the currently low information content of medical case studies on spider bites. Copyright © 2016 Elsevier Ltd. All rights reserved.

Case Study Observational Research: A Framework for Conducting Case Study Research Where Observation Data Are the Focus.

PubMed

Morgan, Sonya J; Pullon, Susan R H; Macdonald, Lindsay M; McKinlay, Eileen M; Gray, Ben V

2017-06-01

Case study research is a comprehensive method that incorporates multiple sources of data to provide detailed accounts of complex research phenomena in real-life contexts. However, current models of case study research do not particularly distinguish the unique contribution observation data can make. Observation methods have the potential to reach beyond other methods that rely largely or solely on self-report. This article describes the distinctive characteristics of case study observational research, a modified form of Yin's 2014 model of case study research the authors used in a study exploring interprofessional collaboration in primary care. In this approach, observation data are positioned as the central component of the research design. Case study observational research offers a promising approach for researchers in a wide range of health care settings seeking more complete understandings of complex topics, where contextual influences are of primary concern. Future research is needed to refine and evaluate the approach.

Statin-Associated Polymyalgia Rheumatica. An Analysis Using WHO Global Individual Case Safety Database: A Case/Non-Case Approach

PubMed Central

de Jong, Hilda J. I.; Saldi, Siti R. F.; Klungel, Olaf H.; Vandebriel, Rob J.; Souverein, Patrick C.; Meyboom, Ronald H. B.; Passier, J. L. M. (Anneke); van Loveren, Henk; Tervaert, Jan Willem Cohen

2012-01-01

Objective To assess whether there is an association between statin use and the occurrence of polymyalgia rheumatic (PMR) in the spontaneous reporting database of the World Health Organisation (WHO). Methods We conducted a case/non-case study based on individual case safety reports (ICSR) in the WHO global ICSR database (VigiBase). Case reports containing the adverse event term polymyalgia rheumatica (WHOART or MedDRA Preferred Term) were defined as cases. Non-cases were all case reports containing other adverse event terms. Each case was matched to five non-cases by age, gender, and time of reporting. Case reports regarding a statin as suspected or concomitant drug were identified using the Anatomical Therapeutic Chemical (ATC) classification. Multivariate logistic regression was used to calculate reporting odds ratios (RORs) with 95% confidence intervals (CI). Results We identified 327 reports of PMR as cases and 1635 reports of other ADRs as non-cases. Among cases, statins were more frequently reported as suspected agent (29.4%) compared to non-cases (2.9%). After adjustment for several covariates, statins were significantly associated with reports of PMR (ROR 14.21; 95% CI 9.89–20.85). Conclusion The results of this study lends support to previous anecdotal case reports in the literature suggesting that the use of a statin may be associated with the occurrence of PMR. Further studies are needed to study the strength of the association in more detail and to elucidate the underlying mechanism. PMID:22844450

An Arizona Border Wall Case Study

DTIC Science & Technology

2017-12-01

WALL CASE STUDY by Justin Alexander Bristow December 2017 Thesis Advisor: Erik Dahl Second Reader: Jorge Gonzalez THIS PAGE...4. TITLE AND SUBTITLE AN ARIZONA BORDER WALL CASE STUDY 5. FUNDING NUMBERS 6. AUTHOR(S) Justin Alexander Bristow 7. PERFORMING ORGANIZATION...PAGE INTENTIONALLY LEFT BLANK iii Approved for public release. Distribution is unlimited. AN ARIZONA BORDER WALL CASE STUDY Justin Alexander

22 CFR 96.47 - Preparation of home studies in incoming cases.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Preparation of home studies in incoming cases... Cases) § 96.47 Preparation of home studies in incoming cases. (a) The agency or person ensures that a home study on the prospective adoptive parent(s) (which for purposes of this section includes the...

22 CFR 96.47 - Preparation of home studies in incoming cases.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Preparation of home studies in incoming cases... Cases) § 96.47 Preparation of home studies in incoming cases. (a) The agency or person ensures that a home study on the prospective adoptive parent(s) (which for purposes of this section includes the...

22 CFR 96.47 - Preparation of home studies in incoming cases.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Preparation of home studies in incoming cases... Cases) § 96.47 Preparation of home studies in incoming cases. (a) The agency or person ensures that a home study on the prospective adoptive parent(s) (which for purposes of this section includes the...

22 CFR 96.47 - Preparation of home studies in incoming cases.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Preparation of home studies in incoming cases... Cases) § 96.47 Preparation of home studies in incoming cases. (a) The agency or person ensures that a home study on the prospective adoptive parent(s) (which for purposes of this section includes the...

22 CFR 96.47 - Preparation of home studies in incoming cases.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Preparation of home studies in incoming cases... Cases) § 96.47 Preparation of home studies in incoming cases. (a) The agency or person ensures that a home study on the prospective adoptive parent(s) (which for purposes of this section includes the...

Security Quality Requirements Engineering (SQUARE): Case Study Phase III

DTIC Science & Technology

2006-05-01

Security Quality Requirements Engineering (SQUARE): Case Study Phase III Lydia Chung Frank Hung Eric Hough Don Ojoko-Adams Advisor...Engineering (SQUARE): Case Study Phase III CMU/SEI-2006-SR-003 Lydia Chung Frank Hung Eric Hough Don Ojoko-Adams Advisor Nancy R. Mead...1 1.1 The SQUARE Process ............................................................................... 1 1.2 Case Study Clients

Executive Headteachers: What's in a Name? Case Study Compendium

ERIC Educational Resources Information Center

Wespieser, Karen, Ed.

2016-01-01

This Case Study Compendium provides an overview of the 12 cases that were investigated as part of the study "Executive Headteachers: What's in a Name?'" (Lord et al., 2016). The case study overviews are based on in-depth analysis and research as described in the full report (ibid) and the Technical Appendix (Harland and Bernardinelli,…

Guidelines for Using Case Studies in the Teaching-Learning Process

ERIC Educational Resources Information Center

McFarlane, Donovan A.

2015-01-01

In this paper, the author expresses concerns regarding the extensive use of case studies in the college classroom and advises college and university faculties to be more careful in their selection and use of case studies as an effective­-based method of teaching. The author communicates the important role that case studies play in teaching and…

Bewitching Ideas Influence Learning: An Evaluation of an Interdisciplinary Teaching Experience

ERIC Educational Resources Information Center

Nava-Whitehead, Susan M.; Augusto, Kerri W.; Gow, Joan-Beth

2011-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. In this month's issue the authors describe an interdisciplinary approach to case study teaching that addresses the demand to balance the goals of process and content. The case study, Salem's Secrets…

78 FR 39769 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-02

... Chautauqua Blvd., Los Angeles, 13000513 Community Clubhouse, 1200 N. Vista St., West Hollywood, 13000510... Study House No. 23A, (Case Study House Program MPS) 2342 Rue de Anne, La Jolla, 13000520 Case Study House No. 23C, (Case Study House Program MPS) 2339 Rue de Anne, La Jolla, 13000521 Ventura County Case...

Integrated Approaches to Testing and Assessment Under ...

EPA Pesticide Factsheets

Presentation on IATA case study for phenols which is joint project with Health Canada and NCCT, presented at the OECD IATA Case Study Meeting No. 2 in Paris, France. Presentation on IATA case study for phenols which is joint project with Health Canada and NCCT, presented at the OECD IATA Case Study Meeting No. 2 in Paris, France.

Effectiveness of Three Case Studies and Associated Teamwork in Stimulating Freshman Interest in an Introduction to Engineering Course

ERIC Educational Resources Information Center

McIntyre, Joseph S.

2011-01-01

The effectiveness of three case studies and associated teamwork to stimulate interest of college freshman in engineering was investigated by observing students. Case studies were assigned as laboratory team exercises in an introduction to engineering course at Auburn University. Student interest in the case studies was evaluated qualitatively…

A Case Study of Project ATHENA: Tactical Level Technological Innovation Aboard the USS Benfold

DTIC Science & Technology

2014-12-01

case studies , grounded theory research , phenomenological research and narrative research . 13 3. Qualitative Methods : Selection The researcher’s...12 B. THE CASE STUDY METHOD 1. Introduction The case study is a type of qualitative research that enables the researcher to chronicle and...objectives and the research environment ultimately determine the

76 FR 71341 - BASINS and WEPP Climate Assessment Tools: Case Study Guide to Potential Applications

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-17

... report presents a series of short case studies designed to illustrate the capabilities of these tools for... change impacts on water. This report presents a series of short case studies using the BASINS and WEPP climate assessment tools. The case studies are designed to illustrate the capabilities of these tools for...

Al-Qaeda-Syria (AQS): An Al-Qaeda Affiliate Case Study

DTIC Science & Technology

2017-10-01

comparative methodology that included eight case studies on groups affiliated or associated with Al-Qaeda. These case studies were then used as a...Case Study Zack Gold With contributions from Pamela G. Faber October 2017 This work was performed under Federal Government...for Stability and Development Center for Strategic Studies REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden

Silicosis in Sandblasters: A Case Study Adapted for Use in U.S. High Schools. NIOSH Case Study in Occupational Epidemiology.

ERIC Educational Resources Information Center

Malit, Bonita D.

This document presents a case study of silicosis in sandblasters that has been adapted for instructional use in U.S. high schools. The primary objective of the case study is to teach students about epidemiology by studying an occupational hazard, disease associated with the hazard, and methods for preventing the disease. The introduction offers…

Risk Management and Performance in the Balkans Support Contract

DTIC Science & Technology

2005-01-01

Defense contracts-United States-Case studies . 2. United States. Army- Procurement-Case studies . 3. Bosnia and Hercegovina-History, Military-20ts...24 3.1. Assessment of GAO Cost Study .................................. 72 3.2. Comparison of Potential Sources of Nonperformance...accepting inappropriate risks, what can it do about it? Case studies of CSS contracts can provide some answers. In this report, we present a case study of

Putting the Learning in Case Learning? The Effects of Case-Based Approaches on Student Knowledge, Attitudes, and Engagement

ERIC Educational Resources Information Center

Krain, Matthew

2016-01-01

This study revisits case learning's effects on student engagement and assesses student learning as a result of the use of case studies and problem-based learning. The author replicates a previous study that used indirect assessment techniques to get at case learning's impact, and then extends the analysis using a pre- and post-test experimental…

Case Study: A Picture Worth a Thousand Words? Making a Case for Video Case Studies

ERIC Educational Resources Information Center

Pai, Aditi

2014-01-01

A picture, they say, is worth a thousand words. If a mere picture is worth a thousand words, how much more are "moving pictures" or videos worth? The author poses this not merely as a rhetorical question, but because she wishes to make a case for using videos in the traditional case study method. She recommends four main approaches of…

Participative Case Studies: Integrating Case Writing and a Traditional Case Study Approach in a Marketing Context

ERIC Educational Resources Information Center

Forman, Howard

2006-01-01

Case-based pedagogy is a valuable tool for applying business concepts and theories to organizational contexts. Traditional case-based pedagogy offers such learning opportunities. What this pedagogy lacks, however, is an element of real-time experiential learning opportunities. This research focuses on the advantages of incorporating a case-writing…

In Case You Teach English: Case Studies in the English Classroom.

ERIC Educational Resources Information Center

Johannessen, Larry R.

Case studies can be a powerful strategy to use for helping students learn critical thinking processes that are key to interpreting and responding to literature and writing. Some of the major benefits of applying case methods are: cases provide an environment for active learning; they encourage the creation of a community of learners; cases help…

Using Case Studies to Enrich Field Experience.

ERIC Educational Resources Information Center

Florio-Ruane, Susan; Clark, Christopher M.

1990-01-01

This paper discusses the use of field experience in teacher education and how it can be augmented by phenomenological case studies. It summarizes a particular case study involving three teacher education classes, noting that reflective analysis of cases can prepare students to observe in the field. (SM)

Pathological characteristics and clinical specifications in gastroenteropancreatic neuroendocrine tumors: a study of 68 cases.

PubMed

Stoica-Mustafa, Elena; Pechianu, C; Iorgescu, Andreea; Hortopan, Monica; Dima, Simona Olimpia; Tomulescu, V; Dumitraşcu, T; Ungureanu, C; Andronesi, D; Popescu, I; Herlea, V

2012-01-01

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) represent a group of tumors, having their origin in cells of diffuse endocrine system, with particular clinical course, diagnosis and treatment. In our study, were included 68 patients with neuroendocrine digestive tumors admitted, diagnosed and treated in Fundeni Clinical Institute, Bucharest, in the last ten years--2000-2010 (retrospective study). Thirty-three (49%) patients were males, 35 (51%) females, and the main age was 58.9 years. In 62 (90.3%) cases was possible to find the primary tumor. The examined tumors had different localizations: pancreas--32 (47.04%) cases (head--17 (24.99%) cases, and body and tail--15 (22.05%) cases), stomach--7 (10.29%) cases, small intestine--7 (10.29%) cases, 6 (8.82%) cases--unknown primary site (diagnosis was established on metastases), right colon--6 (8.82%) cases, liver--6 (8.82%) cases, rectum--2 (2.94%) cases, and retroperitoneum--2 (2.94%) cases. Microscopic examination revealed 59 (86.8%) malignant tumors and 9 (13.2%) benign tumors. Using WHO 2000 Classification, 28 cases of malignant tumors were well-differentiated neuroendocrine carcinomas, and 31 cases were poor differentiated neuroendocrine carcinomas. From malignant cases, 25 (42.3%) have distant metastases and 15 (25.9%) lymph node metastases. Cases of gastroenteropancreatic neuroendocrine tumors included in our study had clinical and histopathological features in correspondence with data from literature--slight predominance in women, predominance in 5th and 6th decades of life, the most frequent localizations were at pancreatic level--both head and body and tail, but the rarest were in colon and retroperitoneum. Most of the cases studied, were malignant tumors, from these more than a half were poor differentiated, and a quarter of them having lymph node or distant metastases.

What Case Managers Should Know About Their Roles and Functions: A National Study From the Commission for Case Manager Certification: Part 1.

PubMed

Tahan, Hussein M; Watson, Annette C; Sminkey, Patrice V

2015-01-01

The purpose of this national role and function study was to identify the essential activities and necessary knowledge areas for effective case manager practice from the perspective of those currently functioning in various care settings and across diverse professional disciplines. The national study covered all case management practices and/or work settings across the full continuum of health care. This cross-sectional descriptive study used the practice analysis method and online survey research design. It employed a purposive sample of case managers, in which 52,370 individuals received an invitation to participate. Data collection completed over a 4-week period, resulting in 7,668 useable survey responses (nearly a 15% response rate). The study identified the common activities and knowledge areas necessary for competent and effective performance of case managers, as is highlighted in this article, which is the first of a 2-part series on the role and function study. The results informed the needed update of the test specifications for the Certified Case Manager (CCM) certification examination, as will be delineated in Part 2 of the article series, to ensure that it continues to be substantiated in current practice. Of special note are the emergence of specific activity and knowledge domains in the area of case management ethical, legal, and practice standards, and an increase in the number of employers requiring certified case managers to fill vacant positions and compensating them financially for such qualifications. This study helps keep the CCM credentialing examination evidence-based and maintain its validity for evaluating competency of case managers. Specifically, the study identified essential activities and knowledge domains that define competent case management practice. Findings can be used for developing programs and curricula for the training and development of case managers. The study instrument also can be used for further research of case management practice.

The South Carolina National Guard Secure Area Duty Officer Program: A Reserve Component Active Shooter Contingency Case Study

DTIC Science & Technology

2017-12-01

SADOP) was authorized as SCNG policy on October 3, 2015. This research constitutes a case study of the SCNG SADOP and catalogs the program from...concealed firearms carry law. C. METHODOLOGY This thesis is a single case study of SADOP, which is an exceptional case and the only one of its kind...CAROLINA NATIONAL GUARD SECURE AREA DUTY OFFICER PROGRAM: A RESERVE COMPONENT ACTIVE SHOOTER CONTINGENCY CASE STUDY by Barry N. Ramey December

Reliability of medical records in diagnosing inflammatory breast cancer in Egypt.

PubMed

Le, Lynne; Schairer, Catherine; Hablas, Ahmed; Meza, Jane; Watanabe-Galloway, Shinobu; Ramadan, Mohamed; Merajver, Sofia D; Seifeldin, Ibrahim A; Soliman, Amr S

2017-03-16

Inflammatory breast cancer (IBC) is a rare, aggressive breast cancer diagnosed clinically by the presence of diffuse erythema, peau d'orange, and edema that arise quickly in the affected breast. This study evaluated the validity of medical records in Gharbiah, Egypt in identifying clinical signs/symptoms of IBC. For 34 IBC cases enrolled in a case-control study at the Gharbiah Cancer Society and Tanta Cancer Center, Egypt (2009-2010), we compared signs/symptoms of IBC noted in medical records to those recorded on a standardized form at the time of IBC diagnosis by clinicians participating in the case-control study. We calculated the sensitivity and specificity of medical records as compared to the case-control study for recording these signs/symptoms. We also performed McNemar's tests. In the case-control study, 32 (94.1%) IBC cases presented with peau d'orange, 30 (88.2%) with erythema, and 31 (91.2%) with edema. The sensitivities of the medical records as compared to the case-control study were 0.8, 0.5, and 0.2 for peau d'orange, erythema, and edema, respectively. Corresponding specificities were 1.0, 0.5, and 1.0. p values for McNemar's test were <0.05 for all signs. Medical records had data on the extent and duration of signs for at most 27% of cases for which this information was recorded in the case-control study. Twenty-three of the 34 cases (67.6%) had confirmed diagnosis of IBC in their medical records. Medical records lacked information on signs/symptoms of IBC, especially erythema and edema, when compared to the case-control study. Deficient medical records could have implications for diagnosis and treatment of IBC and proper documentation of cases in cancer registries.

Psychological Intervention: Case Studies in School Psychological Services, Volume 3, 1979.

ERIC Educational Resources Information Center

Iowa State Dept. of Public Instruction, Des Moines. Div. of Pupil Personnel Services.

The book presents 27 case studies illustrating psychological interventions with behavior problem school children. Studies ususally introduce the target population, describe the method of psychological evaluation, report the results of treatment, and discuss the case's implications. Among cases reported are investigations of stimulant medication on…

Problems of Practice: Canadian Cases in Leadership and Policy

ERIC Educational Resources Information Center

Pollock, Katina; Ryan, James

2013-01-01

One way to support aspiring and current administrators is through the use of case study teaching (Barnes, Christensen, & Hansen, 1994). Using case studies as a teaching and learning tool helps bring real-life situations into principal preparation and support programs. Case study approaches provide students with time to interrogate contemporary…

Report on Federal Productivity. Volume 2, Productivity Case Studies.

ERIC Educational Resources Information Center

Joint Financial Management Improvement Program, Washington, DC.

Volume 2 contains 15 productivity case studies which illustrate and expand on the causal factors mentioned in volume 1. The cases illustrate many different approaches to productivity measurement improvement. The case studies are: Development of an Output-Productivity Measure for the Air Force Medical Service; Measuring Effectiveness and Efficiency…

Using full-cohort data in nested case-control and case-cohort studies by multiple imputation.

PubMed

Keogh, Ruth H; White, Ian R

2013-10-15

In many large prospective cohorts, expensive exposure measurements cannot be obtained for all individuals. Exposure-disease association studies are therefore often based on nested case-control or case-cohort studies in which complete information is obtained only for sampled individuals. However, in the full cohort, there may be a large amount of information on cheaply available covariates and possibly a surrogate of the main exposure(s), which typically goes unused. We view the nested case-control or case-cohort study plus the remainder of the cohort as a full-cohort study with missing data. Hence, we propose using multiple imputation (MI) to utilise information in the full cohort when data from the sub-studies are analysed. We use the fully observed data to fit the imputation models. We consider using approximate imputation models and also using rejection sampling to draw imputed values from the true distribution of the missing values given the observed data. Simulation studies show that using MI to utilise full-cohort information in the analysis of nested case-control and case-cohort studies can result in important gains in efficiency, particularly when a surrogate of the main exposure is available in the full cohort. In simulations, this method outperforms counter-matching in nested case-control studies and a weighted analysis for case-cohort studies, both of which use some full-cohort information. Approximate imputation models perform well except when there are interactions or non-linear terms in the outcome model, where imputation using rejection sampling works well. Copyright © 2013 John Wiley & Sons, Ltd.

Is routine postoperative gastrografin study needed after laparoscopic sleeve gastrectomy? Experience of 712 cases.

PubMed

Wahby, M; Salama, A F; Elezaby, A F; Belgrami, F; Abd Ellatif, M E; El-Kaffas, H F; Al-Katary, M

2013-11-01

The current standard of care is to perform a postoperative gastrografin study following laparoscopic sleeve gastrectomy (LSG) to detect leakage or obstruction. This study evaluated the usefulness of this routine procedure. A retrospective chart review was performed in December 2012. All patients had routine intraoperative methylene blue testing to check for possible leakage from the staple line, and any leaking points were oversewn. We also performed postoperative contrast study (gastrografin) routinely in the first 24-48 h for all patients. From June 2007 to December 2012, 712 cases underwent LSG during the study period. Patients included in this study were 556 women (78.1%) and 156 men (21.9%). The mean age was 35 years. The mean BMI was 48 kg/m2. The operative time was 107 ± 29 min, and there were no conversions to open surgery. Intraoperative methylene blue test detected leakage in 28 cases (3.93%). Postoperative contrast study (gastrografin) was negative for leakage in all cases. Computed tomography (CT) scan with oral contrast study detected leakage in 1.4% (ten cases); none of these cases were detected by regular contrast study. Our study showed that intraoperative methylene blue test for leakage is a very sensitive and effective method for detecting leakage during sleeve gastrectomy and should be done routinely in all cases. Routine postoperative contrast study is not needed to detect leakage unless clinically indicated in selected cases, and in such cases contrast-enhanced CT scans are the modality of choice.

Impact of an Engineering Case Study in a High School Pre-Engineering Course

ERIC Educational Resources Information Center

Rutz, Eugene; Shafer, Michelle

2011-01-01

Students at an all-girls high school who were enrolled in an introduction to engineering course were presented an engineering case study to determine if the case study affected their attitudes toward engineering and their abilities to solve engineering problems. A case study on power plants was implemented during a unit on electrical engineering.…

The Effectiveness of a Case Study-Based First-Year Biology Class at a Black Women's College

ERIC Educational Resources Information Center

Pai, Aditi; Benning, Tracy; Woods, Natasha; McGinnis, Gene; Chu, Joanne; Netherton, Josh; Bauerle, Cynthia

2010-01-01

The authors used a case study-based approach in the introductory biology course at Spelman College. The course taught to entering freshmen was divided into three modules--ecology, evolution, and biodiversity, each designed around a case study. They noted that (1) case study teaching was dramatically more effective than the traditional lecture…

Flawed Execution: A Case Study on Operational Contract Support

DTIC Science & Technology

2016-06-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA JOINT APPLIED PROJECT FLAWED EXECUTION: A CASE STUDY ON OPERATIONAL CONTRACT SUPPORT June 2016...applied project 4. TITLE AND SUBTITLE FLAWED EXECUTION: A CASE STUDY ON OPERATIONAL CONTRACT SUPPORT 5. FUNDING NUMBERS 6. AUTHOR(S) Scott F...unlimited FLAWED EXECUTION: A CASE STUDY ON OPERATIONAL CONTRACT SUPPORT Scott F. Taggart, Captain, United States Marine Corps Jacob Ledford

Finding The Limit: The Strategic Potential Of The Network Based Actor

DTIC Science & Technology

2016-12-01

6  E.  CASE STUDY SELECTION AND PROCESS .......................................6  1.  Selection of Baseline Case Studies: Pierre-Charles...Pathé and the Trust ..................................................................................7  2.  Selection of Test Case Studies...academic debate, which argues that non-state, network-based actors can have a strategic planning capacity. E. CASE STUDY SELECTION AND PROCESS This

Hindsight Is 20/20: A Case Study of Vision and Reading Issues Sheds Light for Teacher Education Programs

ERIC Educational Resources Information Center

Chandler, Kristie B.; Box, Jean A.

2012-01-01

This paper presents a case study designed to educate students in pre-service teacher education programs about the importance of a comprehensive eye exam. The case study chronicles a family's multi-year search for solutions to their child's reading difficulties. The research supporting the case study explores the connection between vision…

Case Studies in the Organizational Communication Course: Applying Textbook Concepts to Real Life Organizations.

ERIC Educational Resources Information Center

Byers, Peggy Yuhas

This paper urges the use of case study discussions in the organizational communication class as an effective instructional technique. The paper presents a variety of formats for bringing case studies to life for students in the organizational communication course. It first discusses sources for case studies such as the World Wide Web, local and…

WeSaySo Case Study: Designing and Implementing a Case Study for Use in an Instructional Design Class.

ERIC Educational Resources Information Center

Graves, Rick; Barnett, Mardee; Gamble, Yolanda; Kolak, Mike

A case study was used in an instructional design class to facilitate the transfer of conceptual knowledge to concrete concerns and to aid instructional technology graduate students' understanding of the steps involved in designing, analyzing, and implementing an effective needs analysis. The case study involved real events at fictitious company…

The Fish Kill Mystery: Using Case Studies in the Middle School Classroom

ERIC Educational Resources Information Center

Heid, Christy; Biglan, Barbara; Ritson, Margaret

2008-01-01

Case studies are an excellent method for engaging middle school students in the current work of scientists. Students learn to think like scientists as they decide how to investigate the dilemma presented in the case study. This article describes one such case study, the Fish Kill Mystery, which takes place at a popular vacation spot--the beaches…

Benefits from Funding the MSD Engineering List: A Fiscal Year 1999 Case Study

DTIC Science & Technology

2004-03-01

BENEFITS FROM FUNDING THE MSD ENGINEERING LIST: A FISCAL YEAR 1999 CASE STUDY THESIS...States Government. AFIT/GLM/ENS/04-03 BENEFITS FROM FUNDING THE MSD ENGINEERING LIST: A FISCAL YEAR 1999 CASE STUDY...ENS/04-03 BENEFITS FROM FUNDING THE MSD ENGINEERING LIST: A FISCAL YEAR 1999 CASE STUDY David L. Gehrich, BS Captain, USAF

Relationship between geomorphology and lithotypes of lahar deposit from Chokai volcano, Japan

NASA Astrophysics Data System (ADS)

Minami, Y.; Ohba, T.; Hayashi, S.; Kataoka, K.

2013-12-01

Chokai volcano, located in the northern Honshu arc in Japan, is an andesitic stratovolcano that collapsed partly at ca. 2500 years ago. A post collapse lahar deposit (Shirayukigawa lahar deposit) is distributed in the northern foot of the volcanic edifice. The deposit consists of 16 units of debris flow, hyperconcentrated flow and streamflow deposits. The Shirayukigawa lahar deposit has a total thickness of 30 m and overlies the 2.5-ka Kisakata debris avalanche deposit. Shirayukigawa lahar deposit forms volcanic fan and volcanic apron. The volcanic fan is subdivided into four areas on the basis of slope angles and of geomorphological features: 1) steeply sloped area, 2) moderately sloped area, 3) gently sloped area and 4) horizontal area. From sedimentary facies and structures, each unit of the Shirayukigawa lahar deposit is classified into one of four lithotypes: clast-supported debris flow deposit (Cc), matrix-supported debris flow deposit (Cm1), hyperconcentrated flow deposit (Cm2) and streamflow deposit (Sl). Each type has the following lithological characteristics. The lithotypes are well correlated with the geomorphology of the volcanic fan. The steeply-sloped and the moderately-sloped areas are dominated by Cc, Cm1, and Cm2, and The horizontal area are dominated by Sl. Debris flow deposit (Cc) is massive, very poorly sorted, partly graded, and clast-supported with polymictic clasts dominated by subrounded to rounded volcanic clasts. Matrix is sandy to muddy. Preferred clast orientation are present. Debris flow deposit (Cm1) is massive, very poorly sorted, and matrix-supported with polymictic clasts dominated by subrounded to rounded volcanic clasts. Matrix is sandy to muddy. Some layers exhibit coarse-tail normal/inverse grading. Most clasts are oriented. Hyperconcentrated flow deposit (Cm2) is massive to diffusely laminated, very poorly sorted and matrix-supported with polymictic clasts dominated by subrounded to rounded volcanic rocks. Matrix is sandy. The clasts are randomly distributed in the sandy matrix except for some clast-concentrated lenticular layers. Clasts smaller than 1cm account for about 10 percent of the deposits. Maximum clast size is about 30 cm. Streamflow deposit (Sl) is weakly parallel/cross-laminated, sorted and partly graded. The deposit contains volcanic clasts smaller than 20cm, which clasts are preferentially oriented and account for about 5% of the deposit. Clasts of the deposits consist of altered andesite, fresh andesite, mudstone and sandstone. The sedimentary clasts were derived from the substrate. The proportion of altered andesite clasts decreases upwards through the units. Matrix components in the lower eight units (C-LHR) are different from those of the upper eight units (S-LHR). In C-LHR units, grayish blue clay is dominant in matrix, whereas in S-LHR units, brownish yellow volcanic sand is dominant in matrix. Hydrothermal clay minerals such as smectite, chlorite, pyrophyllite and kaoline group minerals are rich in C-LHR units, whereas they are poor in S-LHR units. The stratigraphic variation in matrix component reflects temporal variation in supplied materials from source region.

Mapping argillic and advanced argillic alteration in volcanic rocks, quartzites, and quartz arenites in the western Richfield 1° x 2 ° quadrangle, southwestern Utah, using ASTER satellite data

USGS Publications Warehouse

Rockwell, Barnaby W.; Hofstra, Albert H.

2012-01-01

The Richfield quadrangle in southwestern Utah is known to contain a variety of porphyry Mo, skarn, polymetallic replacement and vein, alunite, and kaolin resources associated with 27-32 Ma calc-alkaline or 12-23 Ma bimodal volcano-plutonic centers in Neoproterozoic to Mesozoic carbonate and siliciclastic rocks. Four scenes of visible to shortwave-infrared image data acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor were analyzed to generate maps of exposed clay, sulfate, mica, and carbonate minerals, and ASTER thermal infrared data were analyzed to identify quartz and carbonate minerals. Argillic and advanced argillic alteration minerals including alunite, pyrophyllite, dickite, and kaolinite were identified in both undocumented (U) and known (K) areas, including in the southern Paradise Mtns. (U); in calc-alkaline volcanic rocks in the Wah Wah Mtns. between Broken Ridge and the NG area (U/K); at Wah Wah Summit in a small zone adjacent to 33.1 Ma diorite and marble (U); in fractures cutting quartzites surrounding the 20-22 Ma Pine Grove Mo deposit (U); in volcanic rocks in the Shauntie Hills (U/K); in quartzites in the west-central San Francisco Mtns. (U); in volcanic rocks in the Black Mtns. (K); and in mainly 12-13 Ma rhyolitic rocks along a 20 km E-W belt that includes the Bible Spring fault zone west of Broken Ridge, with several small centers in the Escalante Desert to the south (U/K). Argillized Navajo Sandstone with kaolinite and (or) dickite ± alunite was mapped adjacent to calc-alkaline intrusions in the Star Range (U). Intense quartz-sericite alteration (K) with local kaolinite was identified in andesite adjacent to calc-alkaline intrusions in the Beaver Lake Mountains. Mo-bearing phyllic alteration was identified in 22.2 Ma rhyolite plugs at the center of the NG alunite area. Limestones, dolomites, and marbles were differentiated, and quartz and sericite were identified in most unaltered quartzites. Halos of argillically-altered rock ≈12 km in diameter surround the Pine Grove deposit, the central rhyolites at NG, and the North Peaks just south of the Bible Spring fault zone. A southward shift from 22-23 Ma alunite at NG in the northeast to the 12-13 Ma alunite near Broken Ridge in the southwest mirrors a shift in the locus of bimodal magmatism and is similar to the southward shift of activity from the Antelope Range to Alunite Ridge (porphyry Mo potential) in the Marysvale volcanic field farther east. The poster provided in this report compares mineral maps generated from analysis of combined visible-near infrared (VNIR) and shortwave-infrared (SWIR) data and thermal infrared (TIR) ASTER data to a previously published regional geologic map. Such comparisons are used to identify and differentiate rock-forming and hydrothermal alteration-related minerals, which aids in lithologic mapping and alteration characterization over an 11,245 square kilometer area.

Paleoproterozoic high-sulfidation mineralization in the Tapajós gold province, Amazonian Craton, Brazil: geology, mineralogy, alunite argon age, and stable-isotope constraints

USGS Publications Warehouse

Juliani, Caetano; Rye, Robert O.; Nunes, Carmen M.D.; Snee, Lawrence W.; Correa, Rafael H.; Monteiro, Lena V.S.; Bettencourt, Jorge S.; Neumann, Rainer; Neto, Arnaldo A.

2005-01-01

The Brazilian Tapajós gold province contains the first evidence of high-sulfidation gold mineralization in the Amazonian Craton. The mineralization appears to be in large nested calderas. The Tapajós–Parima (or Ventuari–Tapajós) geological province consists of a metamorphic, igneous, and sedimentary sequence formed during a 2.10 to 1.87 Ga ocean−continent orogeny. The high-sulfidation mineralization with magmatic-hydrothermal alunite is related to hydrothermal breccias hosted in a rhyolitic volcanic ring complex that contains granitic stocks ranging in age from 1.89 to 1.87 Ga. Cone-shaped hydrothermal breccias, which flare upward, contain vuggy silica and have an overlying brecciated cap of massive silica; the deposits are located in the uppermost part of a ring-structure volcanic cone. Drill cores of one of the hydrothermal breccias contain alunite, natroalunite, pyrophyllite, andalusite, quartz, rutile, diaspore, woodhouseite–svanbergite, kaolinite, and pyrite along with inclusions of enargite–luzonite, chalcopyrite, bornite, and covellite. The siliceous core of this alteration center is surrounded by advanced argillic and argillic alteration zones that grade outward into large areas of propylitically altered rocks with sericitic alteration assemblages at depth. Several occurrences and generations of alunite are observed. Alunite is disseminated in the advanced argillic haloes that envelop massive and vuggy silica or that underlie the brecciated silica cap. Coarse-grained alunite also occurs in branching veins and locally is partly replaced by a later generation of fine-grained alunite. Silicified hydrothermal breccias associated with the alunite contain an estimated reserve of 30 tonnes of gold in rock that grades up to 4.5 g t−1 Au. Seven alunite samples gave 40Ar/39Ar ages of 1.869 to 1.846 Ga, with various degrees of apparent minor Ar loss. Stable isotopic data require a magmatic-hydrothermal origin for the alunite, typical for high-sulfidation mineralization. The δ34S values of most samples of alunite range from 14.0‰ to 36.9‰. Sulfur isotopic alunite–pyrite and oxygen isotopic alunite SO4−OH temperatures range from 130 to 420 °C. The δDH2O and δ18OH2O values for alunite-forming hydrothermal fluids suggest a predominance of magmatic water, with a small meteoric contribution. A rare sample of supergene alunite has a δ34S value of 4.1‰ and an 40Ar/39Ar age of 51.3±0.1 Ma. Other than local foliation in the volcanic rocks and recrystallization of alunite near faults, the mineralization and associated alteration appears to have been remarkably undisturbed by later metamorphism and by supergene alteration. The Au mineralization was preserved because of burial by sediments and tuffs in taphrogenic basins that probably developed shortly after mineralization and were probably first exhumed at about 60 Ma. Because high-sulfidation mineralization forms at relatively shallow crustal levels, the discoveries in Tapajós province provide new perspectives for mineral exploration for the Amazonian and perhaps for other Precambrian cratons.

Recall bias in melanoma risk factors and measurement error effects: a nested case-control study within the Norwegian Women and Cancer Study.

PubMed

Parr, Christine L; Hjartåker, Anette; Laake, Petter; Lund, Eiliv; Veierød, Marit B

2009-02-01

Case-control studies of melanoma have the potential for recall bias after much public information about the relation with ultraviolet radiation. Recall bias has been investigated in few studies and only for some risk factors. A nested case-control study of recall bias was conducted in 2004 within the Norwegian Women and Cancer Study: 208 melanoma cases and 2,080 matched controls were invited. Data were analyzed for 162 cases (response, 78%) and 1,242 controls (response, 77%). Questionnaire responses to several host factors and ultraviolet exposures collected at enrollment in 1991-1997 and in 2004 were compared stratified on case-control status. Shifts in responses were observed among both cases and controls, but a shift in cases was observed only for skin color after chronic sun exposure, and a larger shift in cases was observed for nevi. Weighted kappa was lower for cases than for controls for most age intervals of sunburn, sunbathing vacations, and solarium use. Differences in odds ratio estimates of melanoma based on prospective and retrospective measurements indicate measurement error that is difficult to characterize. The authors conclude that indications of recall bias were found in this sample of Norwegian women, but that the results were inconsistent for the different exposures.

Rethinking Case Study Methodology in Poststructural Research.

PubMed

Mohammed, Shan; Peter, Elizabeth; Gastaldo, Denise; Howell, Doris

2015-03-01

Little consideration has been given to how case study might be used in poststructural research to explore power relations that constitute a phenomenon. Many case study scholars, most notably Robert Yin, adopt a postpositivist perspective that assumes the "truth" can be accessed through applying prescriptive and rigid research techniques. Using a discussion of Michel Foucault's key theoretical ideas and the insights gained through a Foucauldian case study of people with advanced cancer who continue to receive curative treatment, the authors argue for the expansion of case study in poststructural inquiry. They propose that the use of poststructuralist case study is valuable because of the flexibility and comprehensiveness of the methodology, which allows for the exploration of a deeper understanding of the broader discourses that shape a phenomenon, as well as how power/knowledge relations shape the behaviours and perceptions of people. They also introduce the reflexive implications of poststructural case study research. Copyright© by Ingram School of Nursing, McGill University.

Case Studies in Wilderness Medicine.

ERIC Educational Resources Information Center

Gray, Melissa; Tarter, Shana Lee

Five case studies explore issues in wilderness medicine, with emphasis on evacuation decision making. The cases describe medical problems encountered during wilderness trips involving college or high school students. In each case, the situation and facts of the case are outlined, including the patient's medical history and vital signs, and at…

A Study on the Failure of Conventional Deterrence: The Case Study of the Bombardment of Yeonpyeong in 2010

DTIC Science & Technology

2016-12-01

December 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE A STUDY ON THE FAILURE OF CONVENTIONAL DETERRENCE: THE CASE ...Approved for public release. Distribution is unlimited A STUDY ON THE FAILURE OF CONVENTIONAL DETERRENCE: THE CASE STUDY OF THE BOMBARDMENT OF...necessary to analyze these diverse elements comprehensively. E. RESEARCH DESIGN This thesis focuses on a single case study about the bombardment of

Issues of Noncompliance. NCABR 2017 | Science Inventory ...

EPA Pesticide Factsheets

This presentation is a case study to be presented at an animal welfare conference. The purpose of the case study is to allow other animal welfare professionals a chance to work through and discuss an potential noncompliance situation. It is for practice, and to encourage people to learn from each other. Members of oversight organizations will be present to offer their perspectives on the case study as well. The purpose of this case study is to help educate other members of the animal welfare profession. This presentation is a case study to be presented at an animal welfare conference. The purpose of the case study is to allow other animal welfare professionals a chance to work through and discuss an potential noncompliance situation. It is for practice, and to encourage people to learn from each other.

Study designs may influence results: the problems with questionnaire-based case-control studies on the epidemiology of glioma.

PubMed

Johansen, Christoffer; Schüz, Joachim; Andreasen, Anne-Marie Serena; Dalton, Susanne Oksbjerg

2017-03-28

Glioma is a rare brain tumour with a very poor prognosis and the search for modifiable factors is intense. We reviewed the literature concerning risk factors for glioma obtained in case-control designed epidemiological studies in order to discuss the influence of this methodology on the observed results. When reviewing the association between three exposures, medical radiation, exogenous hormone use and allergy, we critically appraised the evidence from both case-control and cohort studies. For medical radiation and hormone replacement therapy (HRT), questionnaire-based case-control studies appeared to show an inverse association, whereas nested case-control and cohort studies showed no association. For allergies, the inverse association was observed irrespective of study design. We recommend that the questionnaire-based case-control design be placed lower in the hierarchy of studies for establishing cause-and-effect for diseases such as glioma. We suggest that a state-of-the-art case-control study should, as a minimum, be accompanied by extensive validation of the exposure assessment methods and the representativeness of the study sample with regard to the exposures of interest. Otherwise, such studies cannot be regarded as 'hypothesis testing' but only 'hypothesis generating'. We consider that this holds true for all questionnaire-based case-control studies on cancer and other chronic diseases, although perhaps not to the same extent for each exposure-outcome combination.

Comparing Management Approaches for Automatic Test Systems: A Strategic Missile Case Study

DTIC Science & Technology

2005-03-01

ground up, and is commonly conducted following five methods : ethnography , grounded theory , case study , phenomenological study , and biography...traditions frequently used (Creswell, 1998:5). The five traditions are biography, phenomenological study , grounded theory study , ethnography , and... Ethnography Biography Case Study Grounded Theory

Conceptualizing juvenile prostitution as child maltreatment: findings from the National Juvenile Prostitution Study.

PubMed

Mitchell, Kimberly J; Finkelhor, David; Wolak, Janis

2010-02-01

Two studies were conducted to identify the incidence (Study 1) and characteristics (Study 2) of juvenile prostitution cases known to law enforcement agencies in the United States. Study 1 revealed a national estimate of 1,450 arrests or detentions (95% confidence interval [CI]: 1,287-1,614) in cases involving juvenile prostitution during a 1-year period. In Study 2, exploratory data were collected from a subsample of 138 cases from police records in 2005. The cases are broadly categorized into three main types: (a) third-party exploiters, (b) solo prostitution, and (c) conventional child sexual abuse (CSA) with payment. Cases were classified into three initial categories based on police orientation toward the juvenile: (a) juveniles as victims (53%), (b) juveniles as delinquents (31%), and (c) juvenile as both victims and delinquents (16%). When examining the status of the juveniles by case type, the authors found that all the juveniles in CSA with payment cases were treated as victims, 66% in third-party exploiters cases, and 11% in solo cases. Findings indicate law enforcement responses to juvenile prostitution are influential in determining whether such youth are viewed as victims of commercial sexual exploitation or as delinquents.

Vitamin C Intake and Pancreatic Cancer Risk: A Meta-Analysis of Published Case-Control and Cohort Studies.

PubMed

Hua, Yong-Fei; Wang, Gao-Qing; Jiang, Wei; Huang, Jing; Chen, Guo-Chong; Lu, Cai-De

2016-01-01

Observational studies inconsistently reported the relationship between vitamin C intake and risk of pancreatic cancer. We conducted a meta-analysis of published case-control and cohort studies to quantify the association. Potentially eligible studies were found on PubMed and EMBASE databases through May 31, 2015. A random-effects model was assigned to compute summary point estimates with corresponding 95% confidence intervals (CIs). Subgroup and meta-regression analyses were also performed to explore sources of heterogeneity. Our final analyses included 20 observational studies comprising nearly 5 thousand cases of pancreatic cancer. When comparing the highest with the lowest categories of vitamin C intake, the summary odds ratio/relative risk for case-control studies (14 studies), cohort studies (6 studies) and all studies combined was 0.58 (95% CI: 0.52-0.66), 0.93 (95% CI: 0.78-1.11) and 0.66 (95% CI: 0.58-0.75), respectively. The difference in the findings between case-control and cohort studies was statistically significant (P < .001). Possible publication bias was shown in the meta-analysis of case-control studies. There is insufficient evidence to conclude any relationship between vitamin C intake and risk of pancreatic cancer. The strong inverse association observed in case-control studies may be affected by biases (eg, recall and selection biases) that particularly affect case-control studies and/or potential publication bias. Future prospective studies of vitamin C intake and pancreatic cancer are needed.

Using Case Studies in Calculus-based Physics

NASA Astrophysics Data System (ADS)

Katz, Debora M.

2006-12-01

Do your students believe that the physics only works in your classroom or laboratory? Or do they see that physics underlies their everyday experience? Case studies in physics help students connect physics principles to their everyday experience. For decades, case studies have been used to teach law, medicine and biology, but they are rarely used in physics. I am working on a calculus-based physics textbook for scientists and engineers. Case studies are woven into each chapter. Stop by and get a case study to test out in your classroom. I would love to get your feedback.

The lack of selection bias in a snowball sampled case-control study on drug abuse.

PubMed

Lopes, C S; Rodrigues, L C; Sichieri, R

1996-12-01

Friend controls in matched case-control studies can be a potential source of bias based on the assumption that friends are more likely to share exposure factors. This study evaluates the role of selection bias in a case-control study that used the snowball sampling method based on friendship for the selection of cases and controls. The cases selected fro the study were drug abusers located in the community. Exposure was defined by the presence of at least one psychiatric diagnosis. Psychiatric and drug abuse/dependence diagnoses were made according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Cases and controls were matched on sex, age and friendship. The measurement of selection bias was made through the comparison of the proportion of exposed controls selected by exposed cases (p1) with the proportion of exposed controls selected by unexposed cases (p2). If p1 = p2 then, selection bias should not occur. The observed distribution of the 185 matched pairs having at least one psychiatric disorder showed a p1 value of 0.52 and a p2 value of 0.51, indicating no selection bias in this study. Our findings support the idea that the use of friend controls can produce a valid basis for a case-control study.

Optimal design of studies of influenza transmission in households. II: comparison between cohort and case-ascertained studies.

PubMed

Klick, B; Nishiura, H; Leung, G M; Cowling, B J

2014-04-01

Both case-ascertained household studies, in which households are recruited after an 'index case' is identified, and household cohort studies, where a household is enrolled before the start of the epidemic, may be used to test and estimate the protective effect of interventions used to prevent influenza transmission. A simulation approach parameterized with empirical data from household studies was used to evaluate and compare the statistical power of four study designs: a cohort study with routine virological testing of household contacts of infected index case, a cohort study where only household contacts with acute respiratory illness (ARI) are sampled for virological testing, a case-ascertained study with routine virological testing of household contacts, and a case-ascertained study where only household contacts with ARI are sampled for virological testing. We found that a case-ascertained study with ARI-triggered testing would be the most powerful design while a cohort design only testing household contacts with ARI was the least powerful. Sensitivity analysis demonstrated that these conclusions varied by model parameters including the serial interval and the risk of influenza virus infection from outside the household.

Evaluating psychiatric case-control studies using the STROBE (STrengthening the Reporting of OBservational Studies in Epidemiology) statement.

PubMed

Goi, Pedro Domingues; Goi, Julia Domingues; Cordini, Kariny Larissa; Ceresér, Keila Mendes; Rocha, Neusa Sica da

2014-01-01

Case-control studies are important in developing clinical and public health knowledge. The STROBE statement (STrengthening the Reporting of OBservational Studies in Epidemiology) was developed to establish a checklist of items that should be included in articles reporting observational studies. Our aim was to analyze whether the psychiatric case-control articles published in Brazilian journals with CAPES Qualis rating B1/B2 in 2009 conformed with the STROBE statement. Descriptive study on psychiatric papers published in Brazilian journals, within the Postgraduate Medical Program on Psychiatry, at Universidade Federal do Rio Grande do Sul. All psychiatric case-control studies from Brazilian Qualis B1/B2 journals of psychiatry, neurology and public health in 2009 were analyzed. The four most specific items of the STROBE statement were used to evaluate whether these studies fitted within the case-control parameters: 1) selection of cases and controls; 2) controlling for bias; 3) statistical analysis; and 4) presentation of results. Sixteen case-control studies were identified, of which eleven (68.75%) were in psychiatry-focused journals. From analysis using the STROBE statement, all of the articles conformed with item 1; two (12.5%) completely conformed with item 2; none completely conformed with item 3; and only three (18.8%) conformed with item 4. The case-control studies analyzed here did not completely conform with the four STROBE statement items for case-control design. In view of the inadequate methodology of the published studies, these findings justify focusing on research and methodology and expanding the investigations on adherence of studies to their designs.

Case Studies for Effective Business Instruction.

ERIC Educational Resources Information Center

McAlister-Kizzier, Donna

This book is designed as a resource for educators who teach business content in a variety of instructional settings. It contains case studies representing all functional areas of business, including corporate training, for grades 7 through graduate education. Chapter 1 provides an overview of the case study method. The history of the case method,…

Using Case-Based Pedagogy in the Philippines: A Narrative Inquiry

NASA Astrophysics Data System (ADS)

Arellano, Elvira L.; Barcenal, Tessie L.; Bilbao, Purita P.; Castellano, Merilin A.; Nichols, Sharon E.; Tippins, Deborah J.

2001-04-01

This study features use of case-based pedagogy as a context for exploring science teacher education reform. A central premise of the study is that science teacher education reform is a complex process characterised by the individual and collective narrative histories of teachers. The study was conducted at West Visayas State University in the Philippines as a collaborative research endeavour involving two US and four Filipino science teacher educators. The centrepiece of this study was a case experience prompted by reflection on prospective and practicing elementary teachers' written cases. Results of the study are presented here as a layered narrative. An initial layer explores how a case, written by a prospective teacher, was interwoven with her past and future life history. A second layer looks at sociocultural and professional tensions that mediated the participants' case experience. A third layer represents how the case experience provided a community that supported critical reflection among the research team members. Implications from the study emphasise that case-based pedagogy can serve as a basis for critical reflection to inform community-based approaches to science teacher education pedagogical and research reform.

A Case Study of the Degree of Collaboration Between Various Levels in the Reparable Chain in the United States Air Force

DTIC Science & Technology

2005-03-01

qualitative research methods , a case study approach was selected to conduct this research . “A case study can be defined as an empirical study ... qualitative in nature, and also described the qualitative research method chosen as a case study . From 49 there, data collection was focused upon... qualitative nature of the research , a qualitative design was used to conduct the

Response rates in case-control studies of cancer by era of fieldwork and by characteristics of study design.

PubMed

Xu, Mengting; Richardson, Lesley; Campbell, Sally; Pintos, Javier; Siemiatycki, Jack

2018-04-09

The purpose of this study was to describe time trends in response rates in case-control studies of cancer and identify study design factors that influence response rate. We reviewed 370 case-control studies of cancer published in 12 journals during indicator years in each of the last four decades. We estimated time trends of response rates and reasons for nonresponse in each of the following types of study subjects: cases, medical source controls, and population controls. We also estimated response rates according to characteristics of study context. Median response rates among cases and population controls were between 75% and 80% in the 1970s. Between 1971 and 2010, study response rates declined by 0.31% per year for cases and 0.78% for population controls. Only a minority of studies reported reasons for nonparticipation; subject refusal was the most common reported reason. Studies conducted in North America had lower median response rates than studies conducted in Europe. In-person and telephone interviews elicited higher response rates than mail questionnaires. Response rates from case-control studies of cancer have declined, and this could threaten the validity of results derived from these studies. Copyright © 2018 Elsevier Inc. All rights reserved.

Case Studies in the Field of Marketing Education: Learner Impact, Case Performance, and Cost Efficiency

ERIC Educational Resources Information Center

Spais, George S.

2005-01-01

The major objective of this study is to identify a methodology that will help educators in marketing to efficiently manage the design, impact, and cost of case studies. It is my intention is to examine the impact of case study characteristics in relation to the degree of learner involvement in the learning process. The author proposes that…

Case Studies for Management Development in Bangladesh. Fourth Book. Parepared for the World Bank/Bangladesh Management Education and Training Project.

ERIC Educational Resources Information Center

McLean, Gary N.

This document contains five case studies of management and finance situations in Bangladesh, which are intended to foster classroom discussion and thereby advance management development in that country. One to four discussion questions follow each case study. The titles and authors of the case studies on management are: "Azir Ahmed & Co.,…

Case Studies for Management Development in Bangladesh. Third Book. Prepared for the World Bank/Bangladesh Management Education and Training Project.

ERIC Educational Resources Information Center

McLean, Gary N.

This document contains 10 case studies of management situations in Bangladesh, which are intended to foster classroom discussion and thereby advance management development in that country. Two to four discussion questions follow each case study. Three case studies on the subject of pay and compensation were prepared by Abu Hossain Siddique; the…

Colombia - A Case Study in Smart Power

DTIC Science & Technology

2014-05-22

COLOMBIA–A CASE STUDY IN SMART POWER A Monograph by John P. Brady Foreign Service Officer United States Agency for...Colombia–A Case Study in Smart Power 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) John P. Brady...of Candidate: John P. Brady Monograph Title: Colombia–A Case Study in Smart Power Approved by: , Monograph Director Robert W

Incorporating ITS into transportation improvement planning : the Seattle Case Study using PRUEVIIN

DOT National Transportation Integrated Search

1998-01-01

This project explored methods to analyze ITS strategies within Major Investment Study (MIS) studies and to apply them in a case study. The case study developed methods to define alternatives, and to estimate impacts and costs at the level required fo...

Building Language Educators: The Implications of Case-Based Pedagogy Using Practicum-Based Student-Teacher-Generated Cases for Pre-Service Language Teacher Education

ERIC Educational Resources Information Center

Cournoyer, Amy Beth

2014-01-01

This case study investigated case-based pedagogy using student-teacher-generated cases as an instructional tool in the preparation of 12 pre-service ESL, Bilingual, and Modern Foreign Language teachers enrolled in a Student Teaching Seminar at a post-secondary institution. In the fall methods course, each participant generated a case study based…

Biomass production in agroforestry and forestry systems on salt-affected soils in South Asia: exploration of the GHG balance and economic performance of three case studies.

PubMed

Wicke, Birka; Smeets, Edward M W; Akanda, Razzaque; Stille, Leon; Singh, Ranjay K; Awan, Abdul Rasul; Mahmood, Khalid; Faaij, Andre P C

2013-09-30

This study explores the greenhouse gas balance and the economic performance (i.e. net present value (NPV) and production costs) of agroforestry and forestry systems on salt-affected soils (biosaline (agro)forestry) based on three case studies in South Asia. The economic impact of trading carbon credits generated by biosaline (agro)forestry is also assessed as a potential additional source of income. The greenhouse gas balance shows carbon sequestration over the plantation lifetime of 24 Mg CO2-eq. ha(-1) in a rice-Eucalyptus camaldulensis agroforestry system on moderately saline soils in coastal Bangladesh (case study 1), 6 Mg CO2-eq. ha(-1) in the rice-wheat- Eucalyptus tereticornis agroforestry system on sodic/saline-sodic soils in Haryana state, India (case study 2), and 96 Mg CO2-eq. ha(-1) in the compact tree (Acacia nilotica) plantation on saline-sodic soils in Punjab province of Pakistan. The NPV at a discount rate of 10% is 1.1 k€ ha(-1) for case study 1, 4.8 k€ ha(-1) for case study 2, and 2.8 k€ ha(-1) for case study 3. Carbon sequestration translates into economic values that increase the NPV by 1-12% in case study 1, 0.1-1% in case study 2, and 2-24% in case study 3 depending on the carbon credit price (1-15 € Mg(-1) CO2-eq.). The analysis of the three cases indicates that the economic performance strongly depends on the type and severity of salt-affectedness (which affect the type and setup of the agroforestry system, the tree species and the biomass yield), markets for wood products, possibility of trading carbon credits, and discount rate. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Case and studies].

PubMed

Schubert, András

2015-11-15

Case studies and case reports form an important and ever growing part of scientific and scholarly literature. The paper deals with the share and citation rate of these publication types on different fields of research. In general, evidence seems to support the opinion that an excessive number of such publications may negatively influence the impact factor of the journal. In the literature of scientometrics, case studies (at least the presence of the term "case study" in the titles of the papers) have a moderate share, but their citation rate is practically equal to that of other publication types.

Combining epidemiology and biomechanics in sports injury prevention research: a new approach for selecting suitable controls.

PubMed

Finch, Caroline F; Ullah, Shahid; McIntosh, Andrew S

2011-01-01

Several important methodological issues need to be considered when designing sports injury case-control studies. Major design goals for case-control studies include the accounting for prior injury risk exposure, and optimal definitions of both cases and suitable controls are needed to ensure this. This article reviews methodological aspects of published sports injury case-control studies, particularly with regard to the selection of controls. It argues for a new approach towards selecting controls for case-control studies that draws on an interface between epidemiological and biomechanical concepts. A review was conducted to identify sport injury case-control studies published in the peer-review literature during 1985-2008. Overall, 32 articles were identified, of which the majority related to upper or lower extremity injuries. Matching considerations were used for control selection in 16 studies. Specific mention of application of biomechanical principles in the selection of appropriate controls was absent from all studies, including those purporting to evaluate the benefits of personal protective equipment to protect against impact injury. This is a problem because it could lead to biased conclusions, as cases and controls are not fully comparable in terms of similar biomechanical impact profiles relating to the injury incident, such as site of the impact on the body. The strength of the conclusions drawn from case-control studies, and the extent to which results can be generalized, is directly influenced by the definition and recruitment of cases and appropriate controls. Future studies should consider the interface between epidemiological and biomechanical concepts when choosing appropriate controls to ensure that proper adjustment of prior exposure to injury risk is made. To provide necessary guidance for the optimal selection of controls in case-control studies of interventions to prevent sports-related impact injury, this review outlines a new case-control selection strategy that reflects the importance of biomechanical considerations, which ensures that controls are selected based on the presence of the same global injury mechanism as the cases. To summarize, the general biomechanical principles that should apply to the selection of controls in future case-control studies are as follows: (i) each control must have been exposed to the same global injury mechanism as the case, (e.g. head impact, fall onto outstretched arm); and (ii) intrinsic (individual) factors (e.g. age, sex, skill level) that might modify the person's response to the relevant biomechanical loads are adjusted when either selecting the controls or are in the analysis phase. The same considerations for control selection apply to other study designs such as matched cohort studies or case-crossover studies.

Improving the Effectiveness of Professional Education: Learning Managerial Accounting via a Complex Case.

ERIC Educational Resources Information Center

Carter, Melissa; And Others

To give students more experience with real situations, many professional schools use case studies in their courses. Creating complex cases, case experiences that immerse students in complex problems, rather than mere case studies that require armchair analysis should help students gain better and more integrated knowledge. Designing, implementing,…

A systematic review of occupational safety and health business cases.

PubMed

Verbeek, Jos; Pulliainen, Marjo; Kankaanpää, Eila

2009-12-01

Business cases are commonly developed as means to rationalize investment. We systematically reviewed 26 reported cases on occupational safety and health (OSH) interventions to assess if health and productivity arguments make a good business case. To be included in the review, studies had to analyze the costs and benefits, including productivity, of an OSH intervention at the enterprise level. We searched Medline and Embase for studies and used Google search in addition. Two reviewers independently selected studies and extracted data. The intervention profitability was calculated in euros (euro in 2008) as the first year's benefits minus the total intervention costs per worker. The payback period was calculated as the intervention costs divided by the first year's benefits. We found three ex-ante and 23 ex-post cases. In 20 cases, the study design was a before-after comparison without a control group. Generally a 100% reduction of injuries or sickness absence was assumed. In two cases, productivity and quality increases were very large. The main benefit was avoided sick leave. Depreciation or discounting was applied only in a minority of cases. The intervention profitability was negative in seven studies, up to euro 500 per employee in 12 studies and more than euro 500 per employee in seven studies. The payback period was less than half a year for 19 studies. Only a few studies included sensitivity analyses. Few ex-ante business cases for management decisions on OSH are reported. Guidelines for reporting and evaluation are needed. Business cases need more sound assumptions on the effectiveness of interventions and should incorporate greater uncertainty into their design. Ex-post evaluation should be based preferably on study designs that control for trends at a time different from that of the intervention.

The Use of Interrupted Case Studies to Enhance Critical Thinking Skills in Biology

PubMed Central

White, Tracy K.; Whitaker, Paul; Gonya, Terri; Hein, Richard; Kroening, Dubear; Lee, Kevin; Lee, Laura; Lukowiak, Andrea; Hayes, Elizabeth

2009-01-01

There has been a dramatic increase in the availability of case studies for use in the biology classroom, and perceptions of the effectiveness of case-study-based learning are overwhelmingly positive. Here we report the results of a study in which we evaluated the ability of interrupted case studies to improve critical thinking in the context of experimental design and the conventions of data interpretation. Students were assessed using further case studies designed to evaluate their ability to recognize and articulate problematic approaches to these elements of experimentation. Our work reveals that case studies have broad utility in the classroom. In addition to demonstrating a small but statistically significant increase in the number of students capable of critically evaluating selected aspects of experimental design, we also observed increased student engagement and documented widespread misconceptions regarding the conventions of data acquisition and analysis. PMID:23653687

Better cancer biomarker discovery through better study design.

PubMed

Rundle, Andrew; Ahsan, Habibul; Vineis, Paolo

2012-12-01

High-throughput laboratory technologies coupled with sophisticated bioinformatics algorithms have tremendous potential for discovering novel biomarkers, or profiles of biomarkers, that could serve as predictors of disease risk, response to treatment or prognosis. We discuss methodological issues in wedding high-throughput approaches for biomarker discovery with the case-control study designs typically used in biomarker discovery studies, especially focusing on nested case-control designs. We review principles for nested case-control study design in relation to biomarker discovery studies and describe how the efficiency of biomarker discovery can be effected by study design choices. We develop a simulated prostate cancer cohort data set and a series of biomarker discovery case-control studies nested within the cohort to illustrate how study design choices can influence biomarker discovery process. Common elements of nested case-control design, incidence density sampling and matching of controls to cases are not typically factored correctly into biomarker discovery analyses, inducing bias in the discovery process. We illustrate how incidence density sampling and matching of controls to cases reduce the apparent specificity of truly valid biomarkers 'discovered' in a nested case-control study. We also propose and demonstrate a new case-control matching protocol, we call 'antimatching', that improves the efficiency of biomarker discovery studies. For a valid, but as yet undiscovered, biomarker(s) disjunctions between correctly designed epidemiologic studies and the practice of biomarker discovery reduce the likelihood that true biomarker(s) will be discovered and increases the false-positive discovery rate. © 2012 The Authors. European Journal of Clinical Investigation © 2012 Stichting European Society for Clinical Investigation Journal Foundation.

Case-control vaccine effectiveness studies: Preparation, design, and enrollment of cases and controls.

PubMed

Verani, Jennifer R; Baqui, Abdullah H; Broome, Claire V; Cherian, Thomas; Cohen, Cheryl; Farrar, Jennifer L; Feikin, Daniel R; Groome, Michelle J; Hajjeh, Rana A; Johnson, Hope L; Madhi, Shabir A; Mulholland, Kim; O'Brien, Katherine L; Parashar, Umesh D; Patel, Manish M; Rodrigues, Laura C; Santosham, Mathuram; Scott, J Anthony; Smith, Peter G; Sommerfelt, Halvor; Tate, Jacqueline E; Victor, J Chris; Whitney, Cynthia G; Zaidi, Anita K; Zell, Elizabeth R

2017-06-05

Case-control studies are commonly used to evaluate effectiveness of licensed vaccines after deployment in public health programs. Such studies can provide policy-relevant data on vaccine performance under 'real world' conditions, contributing to the evidence base to support and sustain introduction of new vaccines. However, case-control studies do not measure the impact of vaccine introduction on disease at a population level, and are subject to bias and confounding, which may lead to inaccurate results that can misinform policy decisions. In 2012, a group of experts met to review recent experience with case-control studies evaluating the effectiveness of several vaccines; here we summarize the recommendations of that group regarding best practices for planning, design and enrollment of cases and controls. Rigorous planning and preparation should focus on understanding the study context including healthcare-seeking and vaccination practices. Case-control vaccine effectiveness studies are best carried out soon after vaccine introduction because high coverage creates strong potential for confounding. Endpoints specific to the vaccine target are preferable to non-specific clinical syndromes since the proportion of non-specific outcomes preventable through vaccination may vary over time and place, leading to potentially confusing results. Controls should be representative of the source population from which cases arise, and are generally recruited from the community or health facilities where cases are enrolled. Matching of controls to cases for potential confounding factors is commonly used, although should be reserved for a limited number of key variables believed to be linked to both vaccination and disease. Case-control vaccine effectiveness studies can provide information useful to guide policy decisions and vaccine development, however rigorous preparation and design is essential. Published by Elsevier Ltd.

The Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) Study Protocol

PubMed Central

Woo, Daniel; Rosand, Jonathan; Kidwell, Chelsea; McCauley, Jacob L.; Osborne, Jennifer; Brown, Mark W.; West, Sandra E.; Rademacher, Eric W.; Waddy, Salina; Roberts, Jamie N.; Koch, Sebastian; Gonzales, Nicole R.; Sung, Gene; Kittner, Steven J.; Birnbaum, Lee; Frankel, Michael; Daniel Testai, Fernando; Hall, Christiana E.; Elkind, Mitchell S. V.; Flaherty, Matthew; Coull, Bruce; Chong, Ji Y.; Warwick, Tanya; Malkoff, Marc; James, Michael L.; Ali, Latisha K.; Worrall, Bradford B.; Jones, Floyd; Watson, Tiffany; Leonard, Anne; Martinez, Rebecca; Sacco, Ralph I; Langefeld, Carl D.

2013-01-01

Background and Purpose Epidemiologic studies of intracerebral hemorrhage (ICH) have consistently demonstrated variation in incidence, location, age at presentation, and outcomes among non-Hispanic white, black, and Hispanic populations. We report here the design and methods for this large, prospective, multi-center case-control study of ICH. Methods The ERICH study is a multi-center, prospective case-control study of ICH. Cases are identified by hot-pursuit and enrolled using standard phenotype and risk factor information and include neuroimaging and blood sample collection. Controls are centrally identified by random digit dialing to match cases by age (+/−5 years), race, ethnicity, gender and metropolitan region. Results As of March 22, 2013, 1,655 cases of ICH had been recruited into the study which is 101.5% of the target for that date and 851 controls had been recruited which is 67.2% of the target for that date (1,267 controls) for a total of 2,506 subjects which is 86.5% of the target for that date (2,897 subjects). Of the 1,655 cases enrolled, 1,640 cases had the case interview entered into the database of which 628 (38%) were non-Hispanic black, 458 (28%) were non-Hispanic white and 554 (34%) were Hispanic. Of the 1,197 cases with imaging submitted, 876 (73.2%) had a 24 hour follow-up CT available In addition to CT imaging, 607 cases have had MRI evaluation. Conclusion The ERICH study is a large, case-control study of ICH with particular emphasis on recruitment of minority populations for the identification of genetic and epidemiologic risk factors for ICH and outcomes after ICH. PMID:24021679

Research participation experiences of informants of suicide and control cases: taken from a case-control psychological autopsy study of people who died by suicide.

PubMed

Wong, Paul W C; Chan, Wincy S C; Beh, Philip S L; Yau, Fiona W S; Yip, Paul S F; Hawton, Keith

2010-01-01

Ethical issues have been raised about using the psychological autopsy approach in the study of suicide. The impact on informants of control cases who participated in case-control psychological autopsy studies has not been investigated. (1) To investigate whether informants of suicide cases recruited by two approaches (coroners' court and public mortuaries) respond differently to the initial contact by the research team. (2) To explore the reactions, reasons for participation, and comments of both the informants of suicide and control cases to psychological autopsy interviews. (3) To investigate the impact of the interviews on informants of suicide cases about a month after the interviews. A self-report questionnaire was used for the informants of both suicide and control cases. Telephone follow-up interviews were conducted with the informants of suicide cases. The majority of the informants of suicide cases, regardless of the initial route of contact, as well as the control cases were positive about being approached to take part in the study. A minority of informants of suicide and control cases found the experience of talking about their family member to be more upsetting than expected. The telephone follow-up interviews showed that none of the informants of suicide cases reported being distressed by the psychological autopsy interviews. The acceptance rate for our original psychological autopsy study was modest. The findings of this study are useful for future participants and researchers in measuring the potential benefits and risks of participating in similar sensitive research. Psychological autopsy interviews may be utilized as an active engagement approach to reach out to the people bereaved by suicide, especially in places where the postvention work is underdeveloped.

Acute respiratory infection case definitions for young children: a systematic review of community-based epidemiologic studies in South Asia.

PubMed

Roth, Daniel E; Gaffey, Michelle F; Smith-Romero, Evelyn; Fitzpatrick, Tiffany; Morris, Shaun K

2015-12-01

To explore the variability in childhood acute respiratory infection case definitions for research in low-income settings where there is limited access to laboratory or radiologic investigations. We conducted a systematic review of community-based, longitudinal studies in South Asia published from January 1990 to August 2013, in which childhood acute respiratory infection outcomes were reported. Case definitions were classified by their label (e.g. pneumonia, acute lower respiratory infection) and clinical content 'signatures' (array of clinical features that would be always present, conditionally present or always absent among cases). Case definition heterogeneity was primarily assessed by the number of unique case definitions overall and by label. We also compared case definition-specific acute respiratory infection incidence rates for studies reporting incidence rates for multiple case definitions. In 56 eligible studies, we found 124 acute respiratory infection case definitions. Of 90 case definitions for which clinical content was explicitly defined, 66 (73%) were unique. There was a high degree of content heterogeneity among case definitions with the same label, and some content signatures were assigned multiple labels. Within studies for which incidence rates were reported for multiple case definitions, variation in content was always associated with a change in incidence rate, even when the content differed by a single clinical feature. There has been a wide variability in case definition label and content combinations to define acute upper and lower respiratory infections in children in community-based studies in South Asia over the past two decades. These inconsistencies have important implications for the synthesis and translation of knowledge regarding the prevention and treatment of childhood acute respiratory infection. © 2015 John Wiley & Sons Ltd.

Study design options in evaluating gene-environment interactions: practical considerations for a planned case-control study of pediatric leukemia.

PubMed

Goodman, Michael; Dana Flanders, W

2007-04-01

We compare methodological approaches for evaluating gene-environment interaction using a planned study of pediatric leukemia as a practical example. We considered three design options: a full case-control study (Option I), a case-only study (Option II), and a partial case-control study (Option III), in which information on controls is limited to environmental exposure only. For each design option we determined its ability to measure the main effects of environmental factor E and genetic factor G, and the interaction between E and G. Using the leukemia study example, we calculated sample sizes required to detect and odds ratio (OR) of 2.0 for E alone, an OR of 10 for G alone and an interaction G x E of 3. Option I allows measuring both main effects and interaction, but requires a total sample size of 1,500 cases and 1,500 controls. Option II allows measuring only interaction, but requires just 121 cases. Option III allows calculating the main effect of E, and interaction, but not the main effect of G, and requires a total of 156 cases and 133 controls. In this case, the partial case-control study (Option III) appears to be more efficient with respect to its ability to answer the research questions for the amount of resources required. The design options considered in this example are not limited to observational epidemiology and may be applicable in studies of pharmacogenomics, survivorship, and other areas of pediatric ALL research.

A Homogenization Approach for Design and Simulation of Blast Resistant Composites

NASA Astrophysics Data System (ADS)

Sheyka, Michael

Structural composites have been used in aerospace and structural engineering due to their high strength to weight ratio. Composite laminates have been successfully and extensively used in blast mitigation. This dissertation examines the use of the homogenization approach to design and simulate blast resistant composites. Three case studies are performed to examine the usefulness of different methods that may be used in designing and optimizing composite plates for blast resistance. The first case study utilizes a single degree of freedom system to simulate the blast and a reliability based approach. The first case study examines homogeneous plates and the optimal stacking sequence and plate thicknesses are determined. The second and third case studies use the homogenization method to calculate the properties of composite unit cell made of two different materials. The methods are integrated with dynamic simulation environments and advanced optimization algorithms. The second case study is 2-D and uses an implicit blast simulation, while the third case study is 3-D and simulates blast using the explicit blast method. Both case studies 2 and 3 rely on multi-objective genetic algorithms for the optimization process. Pareto optimal solutions are determined in case studies 2 and 3. Case study 3 is an integrative method for determining optimal stacking sequence, microstructure and plate thicknesses. The validity of the different methods such as homogenization, reliability, explicit blast modeling and multi-objective genetic algorithms are discussed. Possible extension of the methods to include strain rate effects and parallel computation is also examined.

The evaluation of complex interventions in palliative care: an exploration of the potential of case study research strategies.

PubMed

Walshe, Catherine

2011-12-01

Complex, incrementally changing, context dependent and variable palliative care services are difficult to evaluate. Case study research strategies may have potential to contribute to evaluating such complex interventions, and to develop this field of evaluation research. This paper explores definitions of case study (as a unit of study, a process, and a product) and examines the features of case study research strategies which are thought to confer benefits for the evaluation of complex interventions in palliative care settings. Ten features of case study that are thought to be beneficial in evaluating complex interventions in palliative care are discussed, drawing from exemplars of research in this field. Important features are related to a longitudinal approach, triangulation, purposive instance selection, comprehensive approach, multiple data sources, flexibility, concurrent data collection and analysis, search for proving-disproving evidence, pattern matching techniques and an engaging narrative. The limitations of case study approaches are discussed including the potential for subjectivity and their complex, time consuming and potentially expensive nature. Case study research strategies have great potential in evaluating complex interventions in palliative care settings. Three key features need to be exploited to develop this field: case selection, longitudinal designs, and the use of rival hypotheses. In particular, case study should be used in situations where there is interplay and interdependency between the intervention and its context, such that it is difficult to define or find relevant comparisons.

The contribution of case study design to supporting research on Clubhouse psychosocial rehabilitation.

PubMed

Raeburn, Toby; Schmied, Virginia; Hungerford, Catherine; Cleary, Michelle

2015-10-01

Psychosocial Clubhouses provide recovery-focused psychosocial rehabilitation to people with serious mental illness at over 300 sites in more than 30 countries worldwide. To deliver the services involved, Clubhouses employ a complex mix of theory, programs and relationships, with this complexity presenting a number of challenges to those undertaking Clubhouse research. This paper provides an overview of the usefulness of case study designs for Clubhouse researchers; and suggests ways in which the evaluation of Clubhouse models can be facilitated. The paper begins by providing a brief explanation of the Clubhouse model of psychosocial rehabilitation, and the need for ongoing evaluation of the services delivered. This explanation is followed by an introduction to case study design, with consideration given to the way in which case studies have been used in past Clubhouse research. It is posited that case study design provides a methodological framework that supports the analysis of either quantitative, qualitative or a mixture of both types of data to investigate complex phenomena in their everyday contexts, and thereby support the development of theory. As such, case study approaches to research are well suited to the Clubhouse environment. The paper concludes with recommendations for future Clubhouse researchers who choose to employ a case study design. While the quality of case study research that explores Clubhouses has been variable in the past, if applied in a diligent manner, case study design has a valuable contribution to make in future Clubhouse research.

Teaching Business Demography Using Case Studies.

PubMed

Swanson, David A; Morrison, Peter A

2010-02-01

Many faculty members consider using case studies but not all end up using them. We provide a brief review of what cases are intended to do and identify three ways in which they can be used. We then use an example to illustrate how we have used the case study method in teaching business demography. Among other benefits, we note that the case studies method not only encourages the acquisition of skills by students, but can be used to promote "deep structure learning," an approach naturally accommodates other features associated with the case studies method-the development of critical thinking skills, the use of real world problems, the emphasis of concepts over mechanics, writing and presentation skills, active cooperative learning and the "worthwhileness" of a course. As noted by others, we understand the limitations of the case study method. However, given its strengths, we believe it has a place in the instructional toolbox for courses in business demography. The fact that courses we teach is a testament to our perceived efficacy of this tool.

Rare variant association analysis in case-parents studies by allowing for missing parental genotypes.

PubMed

Li, Yumei; Xiang, Yang; Xu, Chao; Shen, Hui; Deng, Hongwen

2018-01-15

The development of next-generation sequencing technologies has facilitated the identification of rare variants. Family-based design is commonly used to effectively control for population admixture and substructure, which is more prominent for rare variants. Case-parents studies, as typical strategies in family-based design, are widely used in rare variant-disease association analysis. Current methods in case-parents studies are based on complete case-parents data; however, parental genotypes may be missing in case-parents trios, and removing these data may lead to a loss in statistical power. The present study focuses on testing for rare variant-disease association in case-parents study by allowing for missing parental genotypes. In this report, we extended the collapsing method for rare variant association analysis in case-parents studies to allow for missing parental genotypes, and investigated the performance of two methods by using the difference of genotypes between affected offspring and their corresponding "complements" in case-parent trios and TDT framework. Using simulations, we showed that, compared with the methods just only using complete case-parents data, the proposed strategy allowing for missing parental genotypes, or even adding unrelated affected individuals, can greatly improve the statistical power and meanwhile is not affected by population stratification. We conclude that adding case-parents data with missing parental genotypes to complete case-parents data set can greatly improve the power of our strategy for rare variant-disease association.

The Crucial Role of the Operational Artist: A Case Study of Operation Barbarossa

DTIC Science & Technology

2017-05-25

historical case study helps to develop a better understanding of operational art today. Future studies might focus on the limitations and opportunities...The Crucial Role of the Operational Artist: A Case Study of Operation Barbarossa A Monograph by LTC (GS) Hagen H. Ruppelt German Army...a Case Study of Operation Barbarossa 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) LTC (GS) Hagen H

A Case Study of ESD Implementation: Signs of Sustainable Leadership

ERIC Educational Resources Information Center

Iliško, Dzintra; Badyanova, Yelena

2014-01-01

This article presents a case study of two schools that were identified as a result of UNESCO associated schools survey as cases of sustainable leadership and governance. The aim of the study is to present the two cases that were crystalized in the survey carried out at end of the United Nations' "Decade of Education for Sustainable…

Two Case Studies of Beginning Teachers in State-Mandated Induction Programs: The Influence of Institutional Factors.

ERIC Educational Resources Information Center

Paulissen, Margaret O.; And Others

The Teacher Induction Study investigated 2 state-mandated beginning teacher programs and examined the translation of state policy by 4 school districts, 13 individual schools, and 32 classrooms. From the case histories of 16 teams, 2 case histories were selected for further study. One case illustrated how institutional factors influenced team…

Online Case-Based Discussions: Examining Coverage of the Afforded Problem Space

ERIC Educational Resources Information Center

Ertmer, Peggy A.; Koehler, Adrie A.

2014-01-01

Case studies hold great potential for engaging students in disciplinary content. However, little is known about the extent to which students actually cover the problem space afforded by a particular case study. In this research, we compared the problem space afforded by an instructional design case study with the actual content covered by 16…

World Perspective Case Descriptions on Educational Programs for Adults: Chile.

ERIC Educational Resources Information Center

Donoso, Patricio; Gajardo, Marcela

This document contains two case studies of adult education programs in Chile. Both case studies begin with a "face sheet" on which is recorded basic information about the program and the description. The first case study, prepared by Patricio Donoso, reports on Centro El Canelo de Nos, an inservice center for educators who work with…

Case Study: Let's Get Personal--Putting Personality into Your Cases

ERIC Educational Resources Information Center

Herreid, Clyde Freeman

2017-01-01

In this case study, the subject for discussion is the need to use teaching notes in order to add personality to case studies. Personality, it is said, is more important than policy, than demographics, than finances, or amorous peccadillos. Personality is essential. It is the interaction of people that capture our interest, yet, the question is…

78 FR 12764 - Draft Office of Health Assessment and Translation Approach for Systematic Review and Evidence...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-25

... Approach--February 2013 might be needed, OHAT plans to apply it to two case-study evaluations. One case... Availability: Draft OHAT Approach--February 2013 will be available by February 26, 2013, and case-study... framework, describe the contents in the case-study protocols, and respond to questions from the public on...

Problematising Ethnography and Case Study: Reflections on Using Ethnographic Techniques and Researcher Positioning

ERIC Educational Resources Information Center

Parker-Jenkins, Marie

2018-01-01

This paper was prompted by the question, what do we mean by conducting "ethnography"? Is it in fact "case study" drawing on ethnographic techniques? My contention is that in many cases, researchers are not actually conducting ethnography as understood within a traditional sense but rather are engaging in case study, drawing on…

A Case-Based Approach Increases Student Learning Outcomes and Comprehension of Cellular Respiration Concepts

ERIC Educational Resources Information Center

Rybarczyk, Brian J.; Baines, Antonio T.; McVey, Mitch; Thompson, Joseph T.; Wilkins, Heather

2007-01-01

This study investigated student learning outcomes using a case-based approach focused on cellular respiration. Students who used the case study, relative to students who did not use the case study, exhibited a significantly greater learning gain, and demonstrated use of higher-order thinking skills. Preliminary data indicate that after engaging…

The Analysis of a Murder, a Case Study

ERIC Educational Resources Information Center

Dinan, Frank J.; Szczepankiewicz, Steven H.; Carnaham, Melinda; Colvin, Michael T.

2007-01-01

The analysis of a Murder case study can be used in general chemistry or nonscience major chemistry courses to teach data handling and analysis in a non-laboratory context. This case study will help students to respond more enthusiastically and with more interest to a set of material placed before them related to a real case rather than…

Pershing in Mexico: a case study in limited contingency operations

DTIC Science & Technology

2016-05-26

Pershing in Mexico: A Case Study in Limited Contingency Operations A Monograph by MAJ Timothy J. Lawrence United States Army School...DATE (00-MM-YYYY) REPORT TYPE 12. 31-03-2016 SAMS Monograph 4. TITLE AND SUBTITLE Pershing in Mexico: A Case Study in Limited Contingency Operations...Monograph Approval Page Name of Candidate: MAJ Timothy J. Lawrence Monograph Title: Pershing in Mexico: A Case Study in Limited Contingency Operations

Reexamining Ground SOF Command and Control: Does One Size Fit All

DTIC Science & Technology

2016-12-01

Case studies covering varying methods of employment of special operations forces in limited contingencies will be utilized. The case studies focus on ...operating environment, much like an open organization. This research examines three case studies including operation JUST CAUSE in Panama, RESTORE HOPE in... case studies , the HQ elements formed around existing homogenous commands and not a Theater Special Operations Command (TSOC) staff with limited

[Clinical studies on flomoxef in neonates].

PubMed

Tabuki, K; Nishimura, T

1993-07-01

Clinical studies on flomoxef (FMOX) were performed in neonates and the results obtained are summarized as follows. Treatment with FMOX was made in 4 cases of neonatal bacterial infections; 2 cases of sepsis (suspected) and 1 case each of infection of umbilicus and staphylococcal scalded skin syndrome. Results obtained were excellent in 1 case, good in 3 cases. No significant side effects due to the drug were observed in any cases.

Comparison of Success of Clomiphene citrate and Letrozole in Ovulation Induction.

PubMed

Saha, J; Akhter, S; Prasad, I; Siddiq, S

2016-01-01

The study was carried out to evaluate which drug is better in ovulation induction between clomiphene citrate and letrozole. The study was carried out in the infertility unit of Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka and Centre for Assisted Reproduction (CARE) at Bangladesh Institute of Research and Rehabilitation in Diabetes Endocrine and Metabolic Disorders (BIRDEM), Dhaka from January 2007 to December 2007. One hundred and sixty five cases were taken for the study. It was a prospective interventional comparative study of clomiphene citrate and letrozole in infertile cases. The patients were divided into three groups. Group I--newly detected cases of sub fertility studied with clomiphene citrate. Group II--clomiphene citrate resistant cases studied with letrozole, Group III--newly detected cases of sub fertility studied with letrozole. The cases were followed up for outcome; (ovulation). The TVS was done on 12th or 13th day of menstruation and level of serum progesterone on 21st day of menstrual cycle to see the evidence of ovulation. Endometrial thickness was also measured. The data was collected on a predesigned questionnaire. The variables that influenced the study were-age, occupation, socioeconomic status, menstrual cycle, marital age, parity, history of MR, history of abortion, past medical and surgical history. In the current study it was observed that the signs of ovulation were significantly (p<0.05) higher in Group I treated with clomiphene citrate in comparison to Group II clomiphene citrate resistant cases treated with letrozole. The rate of ovulation was higher in Group I than that of Group III treated with letrozole, but the difference was not statistically significant (p>0.05). The signs of ovulation were present in 45(81.8%) cases in Group I, 33(60.0%) cases in Group II and 37(67.3%) cases in Group III. This findings of the study suggested that clomiphene citrate is higher successful than letrozole though not statistically significant. Letrozole can be preferred in clomiphene citrate resistant cases before starting other expensive therapies.

Reverse case study: to think like a nurse.

PubMed

Beyer, Deborah A

2011-01-01

Reverse case study is a collaborative, innovative, active learning strategy that nurse educators can use in the classroom. Groups of students develop a case study and a care plan from a list of medications and a short two- to three-sentence scenario. The students apply the nursing process to thoroughly develop a complete case study written as a concept map. The strategy builds on previous learned information and applies the information to new content, thus promoting critical thinking and problem solving. Reverse case study has been used in both associate and baccalaureate nursing degree theory courses to generate discussion and assist students in thinking like a nurse. 2011, SLACK Incorporated.

IVHS institutional issues and case studies : ADVANCE case study

DOT National Transportation Integrated Search

1994-04-01

This operational test case study is one of six performed in response to a Volpe National Transportation Systems Center technical task directive (TTD) to Science Applications International Corporation (SAIC) entitled, IVHS Institutional Issues and ...

Alternative Fuels Data Center: E85 (Flex Fuel)

Science.gov Websites

. Alternative Fueling Stations by Fuel Type More Ethanol Data | All Maps & Data Case Studies Municipality More Ethanol Case Studies | All Case Studies Publications Ethanol Strong; 2018 Ethanol Industry Outlook

Social media campaigns that make a difference: what can public health learn from the corporate sector and other social change marketers?

PubMed

Freeman, Becky; Potente, Sofia; Rock, Vanessa; McIver, Jacqueline

2015-03-30

A great deal of enthusiasm and interest exists in using social media for public health communications, but few research studies have examined its success in promoting and adopting protective health behaviours. To begin to understand how best to develop effective online social marketing campaigns, this paper provides a summary of success factors and key lessons learnt from selected social media campaign case studies. Case study review Methods: A selection of case studies was reviewed for lessons in campaign development, delivery and evaluation from both the corporate and public health sectors. Information about the objective of the campaign, the tactics used and the lessons learnt was extracted from each case study. Lessons learnt from across the case studies were then sorted according to themes. Lessons from the nine case studies selected were categorised into eight themes: planning, use of social media tools, community, content, personal benefits, promotion, costs and challenges. Outcome evaluation data were lacking in the case studies. Overall, the nine case studies show that social media hold promise in changing user behaviours and that social media are highly effective in recruiting participants and motivating them to take small, concrete actions. The case studies also demonstrate that there is room in social media for targeted, inexpensive, small-scale projects, as well as large, well-funded, mass-reach marketing blitzes. Social media campaign process and impact evaluation measures are readily available. Outcome evaluation models and measures are needed to better assess the effectiveness of social media campaigns in changing health behaviours.

Find a Physician from the Society for Vascular Medicine

MedlinePlus

... by SVM_tweets About SVM Event Calendar Practice Tools Case Study Education Journal Scientific Sessions Website FAQ Copyright © ... Choosing Wisely DVT Toolkit A-Fib Decision Making Tool Job Bank Case Study Current Case Case Archive Submission Guidelines Education ...

Prevalence and spectrum of residual symptoms in Lyme neuroborreliosis after pharmacological treatment: a systematic review.

PubMed

Dersch, R; Sommer, H; Rauer, S; Meerpohl, J J

2016-01-01

Controversy exists about residual symptoms after pharmacological treatment of Lyme neuroborreliosis. Reports of disabling long-term sequels lead to concerns in patients and health care providers. We systematically reviewed the available evidence from studies reporting treatment of Lyme neuroborreliosis to assess the prevalence and spectrum of residual symptoms after treatment. A literature search was performed in three databases and three clinical trial registers to find eligible studies reporting on residual symptoms in patients after pharmacological treatment of LNB. Diagnosis must have been performed according to consensus-derived case definitions. No restrictions regarding study design or language were set. Symptom prevalence was pooled using a random-effects model. Forty-four eligible clinical trials and studies were found: 8 RCTs, 17 cohort studies, 2 case-control studies, and 17 case series. The follow-up period in the eligible studies ranged from 7 days to 20 years. The weighted mean proportion of residual symptoms was 28 % (95 % CI 23-34 %, n = 34 studies) for the latest reported time point. Prevalence of residual symptoms was statistically significantly higher in studies using the "possible" case definition (p = 0.0048). Cranial neuropathy, pain, paresis, cognitive disturbances, headache, and fatigue were statistically significantly lower in studies using the "probable/definite" case definition. LNB patients may experience residual symptoms after treatment with a prevalence of approximately 28 %. The prevalence and spectrum of residual symptoms differ according to the applied case definition. Symptoms like fatigue are not reported in studies using the "probable/definite" case definition. As the "possible" case definition is more unspecific, patients with other conditions may be included. Reports of debilitating fatigue and cognitive impairment after LNB, a "post-Lyme syndrome", could therefore be an artifact of unspecific case definitions in single studies.

25-hydroxyvitamin D and breast cancer, colorectal cancer, and colorectal adenomas: case-control versus nested case-control studies.

PubMed

Grant, William B

2015-02-01

Existing literature includes concerns regarding reliability of case-control studies of breast cancer incidence with respect to 25-hydroxyvitamin D (25(OH)D) concentrations. For breast cancer, only case-control studies consistently find inverse correlations between 25(OH)D and breast cancer. However, for colorectal cancer, nested case-control studies find significant inverse correlations with respect to 25(OH)D concentrations at baseline for mean follow-up times of 7 years. This is a review of results currently existing in literature. I provide evidence that 25(OH)D concentration values are only useful for short follow-up times for breast cancer since it develops rapidly. To support the robust nature of breast cancer case-control studies, I show that results from 11 studies from seven countries align in a robust power-law fit to the odds ratio versus mean 25(OH)D concentrations. Case-control studies of breast cancer incidence rates provide reliable results. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Use of existing systematic reviews for evidence assessments in infectious disease prevention: a comparative case study.

PubMed

Harder, Thomas; Remschmidt, Cornelius; Haller, Sebastian; Eckmanns, Tim; Wichmann, Ole

2016-10-11

Given limited resources and time constraints, the use of existing systematic reviews (SR) for the development of evidence-based public health recommendations has become increasingly important. Recently, a five-step approach for identifying, analyzing, appraising and using existing SRs based on recent guidance by the US Agency for Healthcare Research and Quality (AHRQ) was proposed within the Project on a Framework for Rating Evidence in Public Health (PRECEPT). However, case studies are needed to test whether this approach is useful, what challenges arise and how problems can be solved. In two case studies, the five-step approach was applied to integrate existing SRs in the development of evidence-based public health recommendations. Case study A focused on the role of neonatal sepsis as a risk factor for adverse neurodevelopmental outcome. Case study B examined the efficacy, effectiveness and safety of influenza vaccination during pregnancy. For each step, we report the approach of the review team, discuss challenges and describe solutions. For case study A, one existing SR was identified, while in case study B four SRs were eligible for analysis. We found that comparison of inclusion criteria alone was sufficient to judge on relevance of SRs in case study A, but not B. Although methodological quality of all identified SRs was acceptable, risk of bias assessments of individual studies included in the SRs had to be repeated in both case studies. Particular challenges appeared in case study B where multiple SRs addressed the same research question. With the help of spreadsheets comparing the characteristics of the existing SR we decided to use the most comprehensive one for our evidence synthesis and supplemented the results with those from the other SRs. In both case studies using the complete SR was not possible. The five-step approach provided useful and structured guidance and should be routinely applied when using existing SRs as a basis for evidence-based recommendations in public health. In situations where more than one SR has to be considered, the development of spreadsheets comparing characteristics, inclusion criteria, risk of bias, included studies and outcomes seems useful.

Synthesis of Single-Case Experimental Data: A Comparison of Alternative Multilevel Approaches

ERIC Educational Resources Information Center

Ferron, John; Van den Noortgate, Wim; Beretvas, Tasha; Moeyaert, Mariola; Ugille, Maaike; Petit-Bois, Merlande; Baek, Eun Kyeng

2013-01-01

Single-case or single-subject experimental designs (SSED) are used to evaluate the effect of one or more treatments on a single case. Although SSED studies are growing in popularity, the results are in theory case-specific. One systematic and statistical approach for combining single-case data within and across studies is multilevel modeling. The…

Case Studies Behavior Modification.

ERIC Educational Resources Information Center

Wark, David M.

The case histories of five students enrolled in a university course in how to study are reported. The students ranged in age from 18 to 35, included two males and three females, and varied in school experience from no college in one case and some college in two cases to college degrees in two cases. Students were initially taught to chart their…

Creative Interactive Teaching: Case Method & Other Techniques. Selected Papers of the International Conference on Case Methods Research & Application (16th, Caceres, Spain, 1999).

ERIC Educational Resources Information Center

Klein, Hans E., Ed.

This book presents a selection of papers from the international, interdisciplinary conference of the World Association for Case Method Research & Application. Papers are categorized into seven areas: (1) "International Case Studies" (e.g., event-based entrepreneurship, case studies on consumer complaints, and strategic quality…

Liver histopathology of fatal phosphine poisoning.

PubMed

Saleki, Sepideh; Ardalan, Farid Azmoudeh; Javidan-Nejad, Abdullah

2007-03-02

Two commonly used pesticides in agriculture are phosphides of aluminium and zinc. Both of these metal phosphides act through elaboration of toxic phosphine gas. The poisoning in Iran is mostly oral and suicidal. Phosphine is rapidly absorbed throughout the gastrointestinal tract after ingestion and it is partly carried to the liver by the portal vein. In this study the liver histopathology of fatal poisoning is scrutinized. A descriptive, retrospective study was performed on 38 fatal phosphine poisonings. The slides of liver specimens of the cases were retrieved and studied separately by two pathologists. The poisoning was suicidal in 33 (86.5%) of cases. Portal inflammation was negligible in 37 cases and only in one of the cases, a moderate degree of chronic inflammation accompanied by granuloma formation was observed. Major histopathologic findings were as follows: mild sinusoidal congestion; 12 cases (31.6%), severe sinusoidal congestion; 25 cases (45.8%), central vein congestion; 23 cases (60.5%), centrilobular necrosis; 3 cases (7.9%), hepatocytes nuclear fragmentation; 6 cases (15.8%), sinusoidal clusters of polymorphonuclear leukocytes; 12 cases (31.6%), and mild macrovesicular steatosis; 5 cases (13.2%). Fine isomorphic cytoplasmic vacuoles were observed in 36 cases (94.7%). These vacuoles were distributed uniformly in all hepatic zones in the majority (75%) of cases. This study reveals that the main histopathologic findings of fatal phosphine poisoning in the liver are fine cytoplasmic vacuolization of hepatocytes and sinusoidal congestion.

Role of survivor bias in pancreatic cancer case-control studies.

PubMed

Hu, Zhen-Huan; Connett, John E; Yuan, Jian-Min; Anderson, Kristin E

2016-01-01

The purpose of this study was to evaluate the impact of survivor bias on pancreatic cancer case-control studies. The authors constructed five case-loss scenarios based on the Iowa Women's Health Study cohort to reflect how case recruitment in population-based studies varies by case survival time. Risk factors for disease incidence included smoking, body mass index (BMI), waist circumference, diabetes, and alcohol consumption. Odds ratios (ORs) were estimated by conditional logistic regression and quantitatively compared by the interactions between risk factors and 3-month survival time. Additionally, Kaplan-Meier estimates for overall survival were compared within the subset cohort of pancreatic cancer cases. BMI and waist circumference showed a significant inverse relationship with survival time. Decreasing trends in ORs for BMI and waist circumference were observed with increasing case survival time. The interaction between BMI and survival time based on a cutpoint of 3 months was significant (P < .01) as was the interaction between waist circumference and survival time (P < .01). The findings suggested that case losses could result in survivor bias causing underestimated odds ratios for both BMI and waist circumference, whereas other risk factors were not significantly affected by case losses. Copyright © 2016 Elsevier Inc. All rights reserved.

Effectiveness of integrating case studies in online and face-to-face instruction of pathophysiology: a comparative study.

PubMed

Saleh, Suha M; Asi, Yara M; Hamed, Kastro M

2013-06-01

Due to growing demand from students and facilitated by innovations in educational technology, institutions of higher learning are increasingly offering online courses. Subjects in the hard sciences, such as pathophysiology, have traditionally been taught in the face-to-face format, but growing demand for preclinical science courses has compelled educators to incorporate online components into their classes to promote comprehension. Learning tools such as case studies are being integrated into such courses to aid in student interaction, engagement, and critical thinking skills. Careful assessment of pedagogical techniques is essential; hence, this study aimed to evaluate and compare student perceptions of the use of case studies in face-to-face and fully online pathophysiology classes. A series of case studies was incorporated into the curriculum of a pathophysiology class for both class modes (online and face to face). At the end of the semester, students filled out a survey assessing the effectiveness of the case studies. Both groups offered positive responses about the incorporation of case studies in the curriculum of the pathophysiology class. This study supports the argument that with proper use of innovative teaching tools, such as case studies, online pathophysiology classes can foster a sense of community and interaction that is typically only seen with face-to-face classes, based on student responses. Students also indicated that regardless of class teaching modality, use of case studies facilitates student learning and comprehension as well as prepares them for their future careers in health fields.

Is case-chaos methodology an appropriate alternative to conventional case-control studies for investigating outbreaks?

PubMed

Edelstein, Michael; Wallensten, Anders; Kühlmann-Berenzon, Sharon

2014-08-15

Case-chaos methodology is a proposed alternative to case-control studies that simulates controls by randomly reshuffling the exposures of cases. We evaluated the method using data on outbreaks in Sweden. We identified 5 case-control studies from foodborne illness outbreaks that occurred between 2005 and 2012. Using case-chaos methodology, we calculated odds ratios 1,000 times for each exposure. We used the median as the point estimate and the 2.5th and 97.5th percentiles as the confidence interval. We compared case-chaos matched odds ratios with their respective case-control odds ratios in terms of statistical significance. Using Spearman's correlation, we estimated the correlation between matched odds ratios and the proportion of cases exposed to each exposure and quantified the relationship between the 2 using a normal linear mixed model. Each case-control study identified an outbreak vehicle (odds ratios = 4.9-45). Case-chaos methodology identified the outbreak vehicle 3 out of 5 times. It identified significant associations in 22 of 113 exposures that were not associated with outcome and 5 of 18 exposures that were significantly associated with outcome. Log matched odds ratios correlated with their respective proportion of cases exposed (Spearman ρ = 0.91) and increased significantly with the proportion of cases exposed (b = 0.054). Case-chaos methodology missed the outbreak source 2 of 5 times and identified spurious associations between a number of exposures and outcome. Measures of association correlated with the proportion of cases exposed. We recommended against using case-chaos analysis during outbreak investigations. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Visualization case studies : a summary of three transportation applications of visualization

DOT National Transportation Integrated Search

2007-11-30

The three case studies presented in "Visualization Case Studies" are intended to be helpful to transportation agencies in identifying effective techniques for enhancing and streamlining the project development process, including public outreach activ...

Al Qaeda in the Indian Subcontinent (AQIS): An Al Qaeda Affiliate Case Study

DTIC Science & Technology

2017-10-01

conduct this assessment, CNA used a comparative methodology that included eight case studies on groups affiliated or associated with Al-Qaeda. These case...Case Study Pamela G. Faber and Alexander Powell October 2017 This work was performed under Federal Government Contract No. N00014-16-D-5003. Copyright...Director Center for Stability and Development Center for Strategic Studies REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 Public reporting burden

The Modular need for the Division Signal Battalion

DTIC Science & Technology

2017-06-09

findings and analyzes them to expand on them. It is with these findings and subsequent analysis that the case studies shape the answer to the three...These case studies focus on the signal leadership development and how it occurred in the pre-modular force structure, during modularity, and the...the comparative case study research. The case studies focus on signal leader development in a pre-modular signal force, a modular signal force, and

Civil Wars Hijacked: A Case Study of the Lebanese Civil War

DTIC Science & Technology

2016-06-01

will focus on in-depth case studies of external state actors and their sponsored NSAs and outcomes. The state strategies of... case study because they did not employ NSA relationships on the scale of the three other state actors, and U.S. policy often complimented rather than...HIJACKED: A CASE STUDY OF THE LEBANESE CIVIL WAR by Kyle L. Greenheck June 2016 Thesis Advisor: Sean Everton Co-Advisor: Doowan Lee THIS PAGE

Military Hydrology. Report 12. Case Study Evaluation of Alternative Dam-Breach Flood Wave Methods. Volume 1. Main Report.

DTIC Science & Technology

1986-11-01

Report Organization. .................... 7 *PART 11: CASE STUDIES .......................... 9 Teton Dam Failure Flood. ...................... 9...channel, (3) Laurel Run Dam , and (4) Stillhouse Hollow Dam . The Laurel Run and Teton case studies involved field data sets from actual dam failures. The...hypothetical prismatic channel case study used the Teton reservoir and dam data but replaced the complex Teton Valley geometry with a prismatic channel

Evaluation of the United States Drug War Policy Abroad: A Case Study in Colombia

DTIC Science & Technology

2010-12-01

Case Study in Colombia By: Kevin T. Wright and Joseph S. Hamilton December 2010 Advisors: David R. Henderson, John Enns...States Drug War Policy Abroad: A Case Study in Colombia 6. AUTHOR(S) Kevin T. Wright, Joseph S. Hamilton 5. FUNDING NUMBERS 7. PERFORMING...public release; distribution is unlimited EVALUATION OF THE UNITED STATES DRUG WAR POLICY ABROAD: A CASE STUDY IN COLOMBIA Kevin T. Wright

"To Give an Outsider an Idea of What It Could Be Like": A Case Study of the Creative Representation of Hearing Voices

ERIC Educational Resources Information Center

Flavin, Michael; James, Bethany

2018-01-01

This paper reports on a case study which aims to recreate the hearing voices symptom in schizophrenia. The case study was submitted for a co-curricular module at King's College London by a first-year undergraduate Music student, Bethany James, and was created using the web application, Mahara. The core of the case study consists of a soundscape of…

CASE STUDY RESEARCH: THE VIEW FROM COMPLEXITY SCIENCE

PubMed Central

Anderson, Ruth; Crabtree, Benjamin F.; Steele, David J.; McDaniel, Reuben R.

2005-01-01

Many wonder why there has been so little change in care quality, despite substantial quality improvement efforts. Questioning why current approaches are not making true changes draws attention to the organization as a source of answers. We bring together the case study method and complexity science to suggest new ways to study health care organizations. The case study provides a method for studying systems. Complexity theory suggests that keys to understanding the system are contained in patterns of relationships and interactions among the system’s agents. We propose some of the “objects” of study that are implicated by complexity theory and discuss how studying these using case methods may provide useful maps of the system. We offer complexity theory, partnered with case study method, as a place to begin the daunting task of studying a system as an integrated whole. PMID:15802542

Complex Demands on Teaching Require Innovation: Case Method & Other Techniques. Selected Papers of the International Conference on Case Method Research & Application (17th, Budapest, Hungary, July 2-5, 2000).

ERIC Educational Resources Information Center

Klein, Hans E., Ed.

This book presents a selection of papers from the annual, international, interdisciplinary conference of the World Association for Case Method Research & Application. Papers are categorized into six areas: (1) "Case Studies and Research" (e.g., subjectivity as a source of insight in case study research, evolution of a teaching case,…

First to the Finish Line: A Case Study of First Generation Baccalaureate Degree Completers in the University of Maryland Student Support Services Program

ERIC Educational Resources Information Center

Mahan, Christine Pour

2010-01-01

This study explores factors first generation college graduates identify as impacting their successful baccalaureate degree attainment. This research was conducted using qualitative case study method, and a cross case analysis of individual case summaries was completed. Through a review of degree attainment, persistence, and first generation…

University Teachers' Job Dissatisfaction: Application of Two-Factor Theory--A Case of Pakistani Education System

ERIC Educational Resources Information Center

Mir, Imran Anwar

2012-01-01

This qualitative case study presents the reasons of teachers' job dissatisfaction in the government educational institutes in Pakistan. This case study is based on the two factor theory of Herzberg. The results of this case study reveal four core factors that cause job dissatisfaction among teachers in the public sector universities in developing…

The "Reverse Case Study:" Enhancing Creativity in Case-Based Instruction in Leadership Studies

ERIC Educational Resources Information Center

Atkinson, Timothy N.

2014-01-01

In this application brief I share a case study assignment I used in my "Leadership in Complex Organizations" classes to promote creativity in problem solving. I sorted Ph.D. students into two teams and trained them to use creative writing techniques to "encode" theory into their own cases. A sense of competition emerged. Later,…

Case Study: Crazy about Cryptids--An Ecological Hunt for Nessie and Other Legendary Creatures

ERIC Educational Resources Information Center

Rowe, Matthew P.

2015-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This hybrid case has three overarching and interrelated goals. First, it can be used to familiarize students with a range of ecological concepts and terms. Second, it is intended to engage students in…

The Mystery of the Blue Death: A Case Study in Epidemiology and the History of Science

ERIC Educational Resources Information Center

Muench, Susan Bandoni

2009-01-01

This case study introduces students to John Snow, considered to be one of the founders of both epidemiology and anesthesiology, and a remarkable figure in the history of science. Although historical case studies are often less popular with students than contemporary issues (Herreid 1998), a number of aspects of this case make it attractive to…

Hungarys Alternative to Counter Hybrid Warfare - Small States Weaponized Citizenry

DTIC Science & Technology

2017-06-09

case , the thesis applies qualitative intrinsic case study methodology to answer the primary and secondary research questions. Documents in the...literature review provide two 237 Robert E. Stake, The Art of Case Study Research (Thousand Oaks, CA: SAGE...solution for Hungary. The following paragraphs present criteria for the analysis. Criteria The case study analysis concentrates on the first two

Role of intrapartum transcervical amnioinfusion in patients with meconium-stained amniotic fluid.

PubMed

Bhatia, Pushpa; Reena, Kumari; Nangia, Sangita

2013-03-01

The study was undertaken to evaluate maternal, perinatal outcomes following transcervical intrapartum amnioinfusion in women with meconium-stained amniotic fluid. A prospective comparative study was conducted on 100 women with meconium-stained amniotic fluid in labor. Group A: study group (50 cases) received amnioinfusion. Group B: control group (50 cases) did not receive amnioinfusion. FHR monitoring was done using cardiotocography. Significant relief from variable decelerations was seen in 68.18 % cases in the amnioinfusion group as compared to 7.1 % cases in the control group. 78 % cases who were given amnioinfusion had vaginal delivery as compared to 18 % cases in the control group. Fourteen percent cases in the study group had cesarean delivery as compared to 68 % cases in the control group. Meconium aspiration syndrome was seen in six percent neonates in the study group as compared to 20 % in the control group. Two neonates died in the control group due to meconium aspiration syndrome. There was no maternal mortality or major maternal complication. Intrapartum transcervical amnioinfusion is valuable in patients with meconium-stained amniotic fluid.

Barriers to Implementation of Case Management for Patients With Dementia: A Systematic Mixed Studies Review

PubMed Central

Khanassov, Vladimir; Vedel, Isabelle; Pluye, Pierre

2014-01-01

PURPOSE Results of case management designed for patients with dementia and their caregivers in community-based primary health care (CBPHC) were inconsistent. Our objective was to identify the relationships between key outcomes of case management and barriers to implementation. METHODS We conducted a systematic mixed studies review (including quantitative and qualitative studies). Literature search was performed in MEDLINE, PsycINFO, Embase, and Cochrane Library (1995 up to August 2012). Case management intervention studies were used to assess clinical outcomes for patients, service use, caregiver outcomes, satisfaction, and cost-effectiveness. Qualitative studies were used to examine barriers to case management implementation. Patterns in the relationships between barriers to implementation and outcomes were identified using the configurational comparative method. The quality of studies was assessed using the Mixed Methods Appraisal Tool. RESULTS Forty-three studies were selected (31 quantitative and 12 qualitative). Case management had a limited positive effect on behavioral symptoms of dementia and length of hospital stay for patients and on burden and depression for informal caregivers. Interventions that addressed a greater number of barriers to implementation resulted in increased number of positive outcomes. Results suggested that high-intensity case management was necessary and sufficient to produce positive clinical outcomes for patients and to optimize service use. Effective communication within the CBPHC team was necessary and sufficient for positive outcomes for caregivers. CONCLUSIONS Clinicians and managers who implement case management in CBPHC should take into account high-intensity case management (small caseload, regular proactive patient follow-up, regular contact between case managers and family physicians) and effective communication between case managers and other CBPHC professionals and services. PMID:25354410

Barriers to implementation of case management for patients with dementia: a systematic mixed studies review.

PubMed

Khanassov, Vladimir; Vedel, Isabelle; Pluye, Pierre

2014-01-01

Results of case management designed for patients with dementia and their caregivers in community-based primary health care (CBPHC) were inconsistent. Our objective was to identify the relationships between key outcomes of case management and barriers to implementation. We conducted a systematic mixed studies review (including quantitative and qualitative studies). Literature search was performed in MEDLINE, PsycINFO, Embase, and Cochrane Library (1995 up to August 2012). Case management intervention studies were used to assess clinical outcomes for patients, service use, caregiver outcomes, satisfaction, and cost-effectiveness. Qualitative studies were used to examine barriers to case management implementation. Patterns in the relationships between barriers to implementation and outcomes were identified using the configurational comparative method. The quality of studies was assessed using the Mixed Methods Appraisal Tool. Forty-three studies were selected (31 quantitative and 12 qualitative). Case management had a limited positive effect on behavioral symptoms of dementia and length of hospital stay for patients and on burden and depression for informal caregivers. Interventions that addressed a greater number of barriers to implementation resulted in increased number of positive outcomes. Results suggested that high-intensity case management was necessary and sufficient to produce positive clinical outcomes for patients and to optimize service use. Effective communication within the CBPHC team was necessary and sufficient for positive outcomes for caregivers. Clinicians and managers who implement case management in CBPHC should take into account high-intensity case management (small caseload, regular proactive patient follow-up, regular contact between case managers and family physicians) and effective communication between case managers and other CBPHC professionals and services. © 2014 Annals of Family Medicine, Inc.

A genetic study of autism in Costa Rica: multiple variables affecting IQ scores observed in a preliminary sample of autistic cases.

PubMed

McInnes, L Alison; González, Patricia Jiménez; Manghi, Elina R; Esquivel, Marcela; Monge, Silvia; Delgado, Marietha Fallas; Fournier, Eduardo; Bondy, Pamela; Castelle, Kathryn

2005-03-21

Autism is a heritable developmental disorder of communication and socialization that has not been well studied in Hispanic populations. Therefore, we are collecting and evaluating all possible cases of autism from a population isolate in the Central Valley of Costa Rica (CVCR) for a clinical and genetic study. We are assessing all subjects and parents, as appropriate, using the newly translated Spanish versions of the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) as well as tests of intelligence and adaptive behavior. Detailed obstetric and family medical/psychiatric histories are taken. All cases are tested for Fragile X and will be extensively evaluated for cytogenetic abnormalities. To date we have obtained clinical evaluations on over 76 cases of possible autism referred to our study and report data for the initial 35 complete cases. The mean age of the probands is 6.7 years, and 31 of the 35 cases are male. Twenty-one of the cases have IQs <50 and only 6 cases have IQs > or = 70. Over half of the mothers had complications during pregnancy and/or delivery. No cases have tested positively for Fragile X or PKU. Chromosomal G-banding is not yet complete for all cases. Diagnostic data gathered on cases of autism in the CVCR using Spanish versions of the ADI-R and ADOS look similar to that generated by studies of English-speaking cases. However, only 17% of our cases have IQs within the normal range, compared to the figure of 25% seen in most studies. This result reflects an ascertainment bias in that only severe cases of autism come to treatment in the CVCR because there are no government-sponsored support programs or early intervention programs providing an incentive to diagnose autism. The severity of mental retardation seen in most of our cases may also be exaggerated by the lack of early intervention programs and the use of IQ tests without Costa Rican norms. Still, we must formally train healthcare providers and teachers to recognize and refer autistic cases with normal or near normal IQs that are not seen in treatment.

Using Online Case Studies to Enhance Teacher Preparation

ERIC Educational Resources Information Center

Richman, Laila

2015-01-01

The purpose of this study was to assess the impact interactive, online case studies have on learning for preservice teachers. More specifically, it evaluated whether the use of online case studies in instruction could enhance the level of knowledge the preservice teacher gained from the content material. This study utilized a nonequivalent group,…

The Educational System in Japan: Case Study Findings.

ERIC Educational Resources Information Center

Stevenson, Harold; Lee, Shin-Ying; Nerison-Low, Roberta

This document summarizes the findings of a year-long study that used case studies of specific schools in Japan to collect qualitative data on the Japanese educational experience. From 1994-95 the Case Study Project (a component of the Third International Mathematics and Science Study) collected information from interviews with students, parents,…

Home Start Evaluation Study. Interim Case Studies IIa.

ERIC Educational Resources Information Center

Fein, Robert

This formative evaluation study of Home Start uses a case study approach. A brief case study focuses on the administrative structure and staff resources and responsibilities of National Home Start. Also included are reports on seven local programs developed after two field visits had been made to each program. In the first visit, objectives chosen…

Modalities of Generalization Through Single Case Studies.

PubMed

Zittoun, Tania

2017-06-01

The value of case studies for theory building is still doubted in psychology. The paper argues for the importance of case studies and the possibility of generalizing from these for a specific sociocultural understanding of human development. The paper first clarifies the notion of abduction within case studies, drawing on pragmatists James and Peirce and expanding it with the work of Lewin, and argues that it is the core mechanism that allows generalization from case studies. The second section presents the possibility of generalizing from individual single case studies, for which not only the subjective perspective, but also the dynamics by which the social and cultural environment guide and enable the person's development, have to be accounted for. The third section elaborates the question of institutional case studies, where the challenge is to account both for institutional dynamics, and for persons' trajectories within; this is exemplified with an ongoing study on the process of obtaining citizenship in Switzerland. The paper briefly concludes by highlighting two possible implications of the paper, one concerning the process of theoretical reasoning, the other, the fact that sociocultural psychology could itself be seen as an institution in-the-making.

Case-Cohort Studies: Design and Applicability to Hand Surgery.

PubMed

Vojvodic, Miliana; Shafarenko, Mark; McCabe, Steven J

2018-04-24

Observational studies are common research strategies in hand surgery. The case-cohort design offers an efficient and resource-friendly method for risk assessment and outcomes analysis. Case-cohorts remain underrepresented in upper extremity research despite several practical and economic advantages over case-control studies. This report outlines the purpose, utility, and structure of the case-cohort design and offers a sample research question to demonstrate its value to risk estimation for adverse surgical outcomes. The application of well-designed case-cohort studies is advocated in an effort to improve the quality and quantity of observational research evidence in hand and upper extremity surgery. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Understanding Graduate Women's Reentry Experiences: Case Studies of Four Psychology Doctoral Students in a Midwestern University.

ERIC Educational Resources Information Center

Padula, Marjorie A.; Miller, Dana L.

1999-01-01

Studied the experiences of reentry women in psychology doctoral programs at a research university and illustrates the usefulness of the qualitative case study in exploring women's experiences. Case study research can be a powerful tool for feminist researchers. (SLD)

Transformational change in healthcare: an examination of four case studies.

PubMed

Charlesworth, Kate; Jamieson, Maggie; Davey, Rachel; Butler, Colin D

2016-04-01

Objectives Healthcare leaders around the world are calling for radical, transformational change of our health and care systems. This will be a difficult and complex task. In this article, we examine case studies in which transformational change has been achieved, and seek to learn from these experiences. Methods We used the case study method to investigate examples of transformational change in healthcare. The case studies were identified from preliminary doctoral research into the transition towards future sustainable health and social care systems. Evidence was collected from multiple sources, key features of each case study were displayed in a matrix and thematic analysis was conducted. The results are presented in narrative form. Results Four case studies were selected: two from the US, one from Australia and one from the UK. The notable features are discussed for each case study. There were many common factors: a well communicated vision, innovative redesign, extensive consultation and engagement with staff and patients, performance management, automated information management and high-quality leadership. Conclusions Although there were some notable differences between the case studies, overall the characteristics of success were similar and collectively provide a blueprint for transformational change in healthcare. What is known about the topic? Healthcare leaders around the world are calling for radical redesign of our systems in order to meet the challenges of modern society. What does this paper add? There are some remarkable examples of transformational change in healthcare. The key factors in success are similar across the case studies. What are the implications for practitioners? Collectively, these key factors can guide future attempts at transformational change in healthcare.

Occupational factors and pancreatic cancer.

PubMed Central

Norell, S; Ahlbom, A; Olin, R; Erwald, R; Jacobson, G; Lindberg-Navier, I; Wiechel, K L

1986-01-01

The relation between occupational factors and pancreatic cancer has been studied by two different approaches: a population based case-control study with two series of controls and a retrospective cohort study based on register data. With both approaches, some support was found for an association with occupational exposure to petroleum products. Associations were also indicated with exposure to paint thinner (case-control study) and work in painting and in paint and varnish factories (cohort study), for exposure to detergents, floor cleaning agents, or polish (case-control study) and with floor polishing or window cleaning (cohort study), and for exposure to refuse (case-control study) and work in refuse disposal plants (cohort study). PMID:3790458

Treatment outcomes in 3 modes of orthodontic practice.

PubMed

Poulton, Donald R; Baumrind, Sheldon; Vlaskalic, Vicki

2002-02-01

This study examined differences in pretreatment severity and treatment outcome among orthodontic patients treated in 3 different practice-management modes. Samples of pretreatment (T1) and end of treatment (T2) study casts were selected from traditional private practices (TPP, 3 offices, 81 cases), a dental corporation (COMP, 2 offices, 53 cases), and a dental management service organization (DMSO, 1 office, 36 cases). Orthodontic specialists had treated all patients. Cases were initially selected on a consecutive start basis. From each practice, the first 30 cases satisfying the study criteria were included in the sample. The T1 and T2 study casts were evaluated with the PAR and HLD indexes. The PAR and HLD indexes showed a high level of agreement on T1 cast scores but not on the T2 casts. Mean T1 scores were highest in the COMP cases, followed by the DMSO and the TPP cases. T2 scores were lowest in the TPP cases, followed by the DMSO and the COMP cases. The percentage of PAR score reduction showed that, in all 3 modes, patients were treated to a high standard.

Another look at roles and functions: has hospital case management lost its way?

PubMed

Reynolds, John J

2013-01-01

The purpose of this study was to identify the roles, functions, and types of activities that hospital case managers engage in on a day-to-day basis and that leverage the most amounts of time. Previous studies superimpose a priori categories on research tools. Hospital case management. This study analyzes 4,064 spontaneous, unstructured list serve postings from the American Case Management Association Learning Link list serve from August 15, 2011, to August 18, 2012. The study group was a cross section of 415 case management professionals. The data suggest that hospital case managers' time is inordinately leveraged by issues related to observation status/leveling of patients and the Centers for Medicare and Medicaid Services compliance. The data also suggest that hospital case management has taken a conceptual trajectory that has deviated significantly from what was initially conceived (quality, advocacy, and care coordination) and what is publicly purported. Case management education and practical orientation will need to be commensurate with this emerging emphasis. Case management leadership will need to be adept at mitigating the stresses of role confusion, role conflict, and role ambiguity.

Born for a Noble Cause?--A Case Study on Fanconi Anemia

ERIC Educational Resources Information Center

Elwess, Nancy L.; Butterfield, Savanna R.; Charles, Amanda; DeVeaugh, Maxine C.; Lu, Gloria J.; Shafqat, Hira; Watts, Andrew

2005-01-01

The fictional case study presented here is not based on one case, but is actually based on several cases. College students enrolled in a bioethics course for non-majors wrote it. The case entails the thought processes and decision-making involved in order to save one child suffering from a genetic disorder by producing another child, a "designer…

Do Expert Clinical Teachers Have a Shared Understanding of What Constitutes a Competent Reasoning Performance in Case-Based Teaching?

ERIC Educational Resources Information Center

Gauthier, Geneviève; Lajoie, Susanne P.

2014-01-01

To explore the assessment challenge related to case based learning we study how experienced clinical teachers--i.e., those who regularly teach and assess case-based learning--conceptualize the notion of competent reasoning performance for specific teaching cases. Through an in-depth qualitative case study of five expert teachers, we investigate…

Challenging evidence-based decision-making: a hypothetical case study about return to work.

PubMed

Aas, Randi W; Alexanderson, Kristina

2012-03-01

A hypothetical case study about return to work was used to explore the process of translating research into practice. The method involved constructing a case study derived from the characteristics of a typical, sick-listed employee with non-specific low back pain in Norway. Next, the five-step evidence-based process, including the Patient, Intervention, Co-Interventions and Outcome framework (PICO), was applied to the case study. An inductive analysis produced 10 technical and more fundamental challenges to incorporate research into intervention decisions for an individual with comorbidity. A more dynamic, interactive approach to the evidence-based practice process is proposed. It is recommended that this plus the 10 challenges are validated with real life cases, as the hypothetical case study may not be replicable. Copyright © 2011 John Wiley & Sons, Ltd.

Arsenic Removal from Drinking Water

EPA Science Inventory

Web cast presentation covered six topics: 1), Arsenic Chemistry, 2), Technology Selection/Arsenic Demonstration Program, 3), Case Study 1, 4), Case Study 2,5), Case Study 3, and 6), Media Regeneration Project. The presentation consists of material presented at other training sess...

[Shigellosis outbreak with 146 cases related to a fair].

PubMed

Castell Monsalve, Juan; Gutiérrez Avila, Gonzalo; Rodolfo Saavedra, Remedios; Santos Azorín, Antonia

2008-01-01

On September 3, 2005, the Ciudad Real Public Health Service (Spain) received a report of 20 cases of gastroenteritis in the municipality of Daimiel. We conducted an investigation to determine the cause or causes of the outbreak and to implement control measures. Most of the cases involved young people who visited the municipality's fair. We carried out a descriptive study and an analytic case-control study. In the descriptive study, all variables of interest available in the medical records were included. In the case-control study, each case was matched with a control by age (plus or minus 5 years), gender, and attendance at the fair. Sixty-five cases and 65 controls were finally included in the study. Samples of foods and stools from food handlers were taken. We found 196 cases, 146 of which were confirmed. The epidemic curve suggested a common source of infection with a short period of activity. The case-control study showed an association between infection and eating potatoes with a sauce at any of the fair's five food stalls (OR = 20.56; 95%CI, 6.15-75.93; p < 0.0001). Logistic regression analysis showed an association with eating potatoes in food stall number 2 (OR = 6.38; 95%CI, 1.70-23.90; p < 0.0059). Neither samples of foods nor stools from food handlers yielded any positive results. However, Shigella sonnei was isolated from stool samples from 20 cases. The epidemiological study suggested that the most probable cause of the outbreak was a sauce, handmade with garlic, milk, and oil and served with the potatoes.

A retrospective study of gastric dilatation and gastric dilatation and volvulus in working farm dogs in New Zealand.

PubMed

Hendriks, M M; Hill, K E; Cogger, N; Jones, B R; Cave, N J

2012-05-01

To present findings from a case series of gastric dilatation (GD) or gastric dilatation and volvulus (GDV) in working farm dogs in New Zealand that were examined at veterinary clinics, and to identify possible risk factors for GD or GDV in working farm dogs in New Zealand using a case-control study. This retrospective study included a case-series and a case-control study. The case series analysed information from 62 case records of GD or GDV in working farm dogs seen between August 2004 and September 2009 at 13 veterinary clinics throughout New Zealand. Cases were classified as GD or GDV if the diagnosis was confirmed by radiography, surgery or post-mortem examination. Details of history and treatment, as well as outcomes, were obtained for each case. For the case-control study, records of 41 working farm dogs with GD or GDV (cases) seen between April 2008 and April 2009, and 82 working farm dogs examined because of trauma over the same period and in the same 13 clinics (controls), were used to model the risk factors for GD or GDV. From the case-series study, 40/62 (65%) cases of GD or GDV that were examined and treated at the veterinary clinics returned to work. Of the 41 dogs where the gastric contents were recorded, 25 (61%) had predominantly food or bones in the stomach, and 26/27 dogs had a history of having eaten meat, bones or scavenged a carcass. The case-control study showed that the significant risk factors for GD or GDV, compared with control dogs presenting with trauma, were breed, age and season. The odds that a case of GD or GDV was a Huntaway, after adjusting for age and season, was 19 times higher than the odds a control was a Huntaway. Gender and bodyweight were not identified as risk factors. A high proportion of farm working dogs with GD or GDV were successfully treated by veterinarians. The risk of a case of GD or GDV being a Huntaway was significantly higher than for a dog presenting as a trauma case. However the influences of the season of the year, climatic factors and nutritional factors on the pathogenesis need to be identified before adequate preventative measures can be recommended.

Scientists' attitudes on science and values: Case studies and survey methods in philosophy of science.

PubMed

Steel, Daniel; Gonnerman, Chad; O'Rourke, Michael

2017-06-01

This article examines the relevance of survey data of scientists' attitudes about science and values to case studies in philosophy of science. We describe two methodological challenges confronting such case studies: 1) small samples, and 2) potential for bias in selection, emphasis, and interpretation. Examples are given to illustrate that these challenges can arise for case studies in the science and values literature. We propose that these challenges can be mitigated through an approach in which case studies and survey methods are viewed as complementary, and use data from the Toolbox Dialogue Initiative to illustrate this claim. Copyright © 2017 Elsevier Ltd. All rights reserved.

Case reports and case series in prehospital emergency care research.

PubMed

Patterson, P Daniel; Weaver, Matthew; Clark, Sunday; Yealy, Donald M

2010-11-01

Research begins with a clearly stated question, problem or hypothesis. The selection of a study design appropriate to the task is the next key step. This paper provides guidance for the use of case report and case series designs by describing the 'what', 'when' and 'how' of both designs. Also described is the use of case reports and case series study designs in prehospital emergency research and the quality of published literature from 2000 to mid-2008.

The challenges to gender integration in the career fire services: a comparative case study of men in nursing

DTIC Science & Technology

2017-03-01

GENDER INTEGRATION IN THE CAREER FIRE SERVICES: A COMPARATIVE CASE STUDY OF MEN IN NURSING by Anna L. Schermerhorn-Collins March 2017...IN THE CAREER FIRE SERVICES: A COMPARATIVE CASE STUDY OF MEN IN NURSING 5. FUNDING NUMBERS 6. AUTHOR(S) Anna L. Schermerhorn-Collins 7... comparative case study of men in nursing. Research is based in academic and historical accounts, in addition to the use of participant-observation

A Case Study in Design Thinking Applied Through Aviation Mission Support Tactical Advancements for the Next Generation (TANG)

DTIC Science & Technology

2017-12-01

This is an examination of the research, execution, and follow- on developments supporting the Design Thinking event explored through Case Study ...research, execution, and follow- on developments supporting the Design Thinking event explored through case study methods. Additionally, the lenses of...total there have been two Naval Postgraduate School (NPS) case study theses on U.S. Navy innovation events as well as other works examining the

Integrating Army Aviation into the Combined Arms Team: Operational Art in Desert Shield and Desert Storm

DTIC Science & Technology

2017-05-25

new doctrine, the ideal organization, and what would eventually become a branch. The framework for the historical case study is the doctrinal...operational art were apparent in the case study , and were enabled, either directly or indirectly, by rotary-wing aviation. This case study illuminated the...would eventually become a branch. The framework for the historical case study is the doctrinal relationship between the elements of operational art

BestPractices Corporate Energy Management Case Study: Alcoa Teams with DOE to Reduce Energy Consumption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2004-05-01

This is the first in a series of DOE Industrial Technologies Program case studies on corporate energy management. The case study highlights Alcoa Aluminum's successful results and activities through its corporate energy management approach and collaboration with DOE. Case studies in this series will be used to encourage other energy-intensive industrial plants to adopt a corporate strategy, and to promote the concept of replicating results with a company or industry.

Tumor-based case-control studies of infection and cancer: muddling the when and where of molecular epidemiology.

PubMed

Engels, Eric A; Wacholder, Sholom; Katki, Hormuzd A; Chaturvedi, Anil K

2014-10-01

We describe the "tumor-based case-control" study as a type of epidemiologic study used to evaluate associations between infectious agents and cancer. These studies assess exposure using diseased tissues from affected individuals (i.e., evaluating tumor tissue for cancer cases), but they must utilize nondiseased tissues to assess control subjects, who do not have the disease of interest. This approach can lead to exposure misclassification in two ways. First, concerning the "when" of exposure assessment, retrospective assessment of tissues may not accurately measure exposure at the key earlier time point (i.e., during the etiologic window). Second, concerning the "where" of exposure assessment, use of different tissues in cases and controls can have different accuracy for detecting the exposure (i.e., differential exposure misclassification). We present an example concerning the association of human papillomavirus with various cancers, where tumor-based case-control studies likely overestimate risk associated with infection. In another example, we illustrate how tumor-based case-control studies of Helicobacter pylori and gastric cancer underestimate risk. Tumor-based case-control studies can demonstrate infection within tumor cells, providing qualitative information about disease etiology. However, measures of association calculated in tumor-based case-control studies are prone to over- or underestimating the relationship between infections and subsequent cancer risk. ©2014 American Association for Cancer Research.

Grandma's TUM-my Trouble: A Case Study in Renal Physiology and Acid-Base Balance

ERIC Educational Resources Information Center

Massey, Ann T.

2015-01-01

This case study involves the role of the kidneys in regulating blood pH and electrolytes. The case was used near the end of a two-semester Human Anatomy and Physiology course sequence, during the time when renal physiology was under study. Groups of two to three students were given the case and associated information (lab values, etc.). Students…

Variations on an Historical Case Study: The Extraordinary Accident of Isidro Mejia

ERIC Educational Resources Information Center

Field, Patrick

2006-01-01

Activities using the same historical case study can be designed for courses of varying degrees of proficiency by altering the format to suit each academic level. The case of Isidro Mejia, a construction worker who had six nails accidentally shot into his head from a nail gun, is the basis for a series of case study exercises. (Contains 4 figures.)

Using Case Studies to Promote Student Engagement in Primary Literature Data Analysis and Evaluation

PubMed Central

Cook-Snyder, Denise R.

2017-01-01

Analyzing and evaluating primary literature data is a common learning objective in undergraduate neuroscience courses. However, students with more clinically focused career goals often dismiss the relevance of evaluating basic neuroscience literature. Here, we describe using case studies to promote student engagement in primary literature in a cellular and molecular neuroscience course. Two example literature-based case studies are provided: Untwisting Pretzel Syndrome, a neurodevelopment case exploring synapse formation in a pretzel syndrome patient, and The Trials of ALS, a neurodegeneration case exploring axon degeneration and repair in an amyotrophic lateral sclerosis patient. These cases were assigned after neurodevelopment and neurodegeneration lectures covering key concepts. Both cases begin by introducing the patient and hypothesizing symptoms and diagnoses, followed by scenes incorporating primary data to illustrate disease pathogenesis and treatments. Students complete questions embedded in these cases as homework, and class time is used to discuss their answers. Discussion emphasizes that there can be multiple “correct” answers, and the best answers are accurate and well-supported. Accordingly, students edit their answers in class, and these annotations are factored into a pass/fail grade on the case. Additional scenes and questions from the same case studies are used on the course’s take-home exams, thereby allowing students to practice primary data analysis and evaluation before a graded assignment. Student evaluations support literature-based case studies as an effective learning tool, with students identifying cases as the most valuable aspect of the course, and reporting increased confidence in understanding cellular and molecular neuroscience. PMID:29371850

Using Case Studies to Promote Student Engagement in Primary Literature Data Analysis and Evaluation.

PubMed

Cook-Snyder, Denise R

2017-01-01

Analyzing and evaluating primary literature data is a common learning objective in undergraduate neuroscience courses. However, students with more clinically focused career goals often dismiss the relevance of evaluating basic neuroscience literature. Here, we describe using case studies to promote student engagement in primary literature in a cellular and molecular neuroscience course. Two example literature-based case studies are provided: Untwisting Pretzel Syndrome, a neurodevelopment case exploring synapse formation in a pretzel syndrome patient, and The Trials of ALS, a neurodegeneration case exploring axon degeneration and repair in an amyotrophic lateral sclerosis patient. These cases were assigned after neurodevelopment and neurodegeneration lectures covering key concepts. Both cases begin by introducing the patient and hypothesizing symptoms and diagnoses, followed by scenes incorporating primary data to illustrate disease pathogenesis and treatments. Students complete questions embedded in these cases as homework, and class time is used to discuss their answers. Discussion emphasizes that there can be multiple "correct" answers, and the best answers are accurate and well-supported. Accordingly, students edit their answers in class, and these annotations are factored into a pass/fail grade on the case. Additional scenes and questions from the same case studies are used on the course's take-home exams, thereby allowing students to practice primary data analysis and evaluation before a graded assignment. Student evaluations support literature-based case studies as an effective learning tool, with students identifying cases as the most valuable aspect of the course, and reporting increased confidence in understanding cellular and molecular neuroscience.

Case definitions for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME): a systematic review

PubMed Central

Brurberg, Kjetil Gundro; Fønhus, Marita Sporstøl; Larun, Lillebeth; Flottorp, Signe; Malterud, Kirsti

2014-01-01

Objective To identify case definitions for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), and explore how the validity of case definitions can be evaluated in the absence of a reference standard. Design Systematic review. Setting International. Participants A literature search, updated as of November 2013, led to the identification of 20 case definitions and inclusion of 38 validation studies. Primary and secondary outcome measure Validation studies were assessed for risk of bias and categorised according to three validation models: (1) independent application of several case definitions on the same population, (2) sequential application of different case definitions on patients diagnosed with CFS/ME with one set of diagnostic criteria or (3) comparison of prevalence estimates from different case definitions applied on different populations. Results A total of 38 studies contributed data of sufficient quality and consistency for evaluation of validity, with CDC-1994/Fukuda as the most frequently applied case definition. No study rigorously assessed the reproducibility or feasibility of case definitions. Validation studies were small with methodological weaknesses and inconsistent results. No empirical data indicated that any case definition specifically identified patients with a neuroimmunological condition. Conclusions Classification of patients according to severity and symptom patterns, aiming to predict prognosis or effectiveness of therapy, seems useful. Development of further case definitions of CFS/ME should be given a low priority. Consistency in research can be achieved by applying diagnostic criteria that have been subjected to systematic evaluation. PMID:24508851

Factors associated with unreported tuberculosis cases in Spanish hospitals.

PubMed

Morales-García, Concepción; Rodrigo, Teresa; García-Clemente, Marta M; Muñoz, Ana; Bermúdez, Pilar; Casas, Francisco; Somoza, María; Milá, Celia; Penas, Antón; Hidalgo, Carmen; Casals, Martí; Caylá, Joan A

2015-07-29

Under-reporting of tuberculosis (TB) cases complicates disease control, hinders contact tracing and alters the accuracy of epidemiological data, including disease burden. The objective of the present study is to evaluate the proportion of unreported TB cases in Spanish healthcare facilities and to identify the associated factors. A multi-center retrospective study design was employed. The study included TB cases diagnosed in 16 facilities during 2011-2012. These cases were compared to those reported to the corresponding public health departments. Demographic, microbiological and clinical data were analyzed to determine the factors associated with unreported cases. Associated factors were analyzed on a bivariate level using the x(2) test and on a multivariate level using a logistic regression. Odds ratios (OR) and 95 % confidence intervals (CI) were calculated. Of the 592 TB cases included in the study, 85 (14.4 %) were not reported. The percentage of unreported cases per healthcare center ranged from 0-45.2 %. The following variables were associated to under-reporting at a multivariate level: smear-negative TB (OR = 1.87; CI:1.07-3.28), extrapulmonary disease (OR = 2.07; CI:1.05-4.09) and retired patients (OR = 3.04; CI:1.29-7.18). A nurse case manager was present in all of the centers with 100 % reporting. The percentage of reported cases among the smear-positive cases was 9.4 % and 19.4 % (p = 0.001) among the rest of the study population. Smear-positive TB was no associated to under-reporting. It is important that TB Control Programs encourage thorough case reporting to improve disease control, contact tracing and accuracy of epidemiological data. The help from a TB nurse case manager could improve the rate of under-reporting.

Molasses supplementation of grazing dairy cows: summary of case study, continuous culture fermenter trials, and controlled research farm study

USDA-ARS?s Scientific Manuscript database

This fact sheet summarizes the results of a three-tiered research approach (case study, two continuous culture fermenter studies, and a controlled research farm study) to evaluate molasses as an alternative supplement source for grazing dairy cows. A two-year case study of a New York organic dairy f...

Teaching Agricultural Policy with the Case Method.

ERIC Educational Resources Information Center

Stuhler, E. A.

1994-01-01

Two groups of agriculture students were taught with case studies and one group without (about 30 students in each group). Case-method groups had greater gains in cognitive performance and changed motivation and attitudes. Case studies had a positive effect on the development of problem-solving skills. (SK)

Selecting Cases for Intensive Analysis: A Diversity of Goals and Methods

ERIC Educational Resources Information Center

Gerring, John; Cojocaru, Lee

2016-01-01

This study revisits the task of case selection in case study research, proposing a new typology of strategies that is explicit, disaggregated, and relatively comprehensive. A secondary goal is to explore the prospects for case selection by "algorithm," aka "ex ante," "automatic," "quantitative,"…

Case Study: A Peek behind the Curtain of Tenure and Promotion

ERIC Educational Resources Information Center

Herreid, Clyde Freeman; Prud'homme-Genereux, Annie; Schiller, Nancy A.; Herreid, Ky F.; Wright, Carolyn

2015-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue describes a survey that looks at the system for tenure and promotion.

DIAGNOSTIC TOOL DEVELOPMENT AND APPLICATION THROUGH REGIONAL CASE STUDIES

EPA Science Inventory

Case studies are a useful vehicle for developing and testing conceptual models, classification systems, diagnostic tools and models, and stressor-response relationships. Furthermore, case studies focused on specific places or issues of interest to the Agency provide an excellent ...

Using Case Studies to Teach About Global Issues, Bali: A Case Study

ERIC Educational Resources Information Center

Oswald, James M.

1974-01-01

The South Pacific island of Bali is used as a case study of overpopulation and food shortage. A brief description of the resources, the typical lifestyle of the Balinese farmer, and possible teaching techniques are given. (DE)

A sham case-control study of effectiveness of DTP-Hib-hepatitis B vaccine against rotavirus acute gastroenteritis in Kenya

PubMed Central

2014-01-01

Background In many GAVI-eligible countries, effectiveness of new vaccines will be evaluated by case-control methodology. To inform the design and assess selection bias of a future case-control study of rotavirus vaccine effectiveness (VE) in western Kenya, we performed a sham case-control study evaluating VE of pentavalent vaccine (DTP-Hib-HepB) against rotavirus acute gastroenteritis (AGE). Methods From ongoing rotavirus surveillance, we defined cases as children 12 weeks to 23 months old with EIA-confirmed rotavirus AGE. We enrolled one community-based and two hospital-based control groups. We collected vaccination status from cards at enrollment, or later in homes, and evaluated VE by logistic regression. Results We enrolled 91 cases (64 inpatient, 27 outpatient), 252 non-rotavirus AGE facility-based controls (unmatched), 203 non-AGE facility-based controls (age-matched) and 271 community controls (age-matched). Documented receipt of 3 pentavalent doses was 77% among cases and ranged from 81-86% among controls. One percent of cases and 0-2% of controls had no pentavalent doses. The adjusted odds ratio of three versus zero doses for being a case was 3.27 (95% CI 0.01-1010) for community controls and 0.69 (95% CI 0.06-7.75) for non-rotavirus hospital-based AGE controls, translating to VE of -227% and 31%, respectively, with wide confidence intervals. (No facility-based non-AGE controls were unvaccinated.) Similar results were found for ≥2 pentavalent doses and for severe rotavirus AGE. Conclusions The study showed that it is feasible to carry out a real case control in the study area, but this needs to be done as soon as the vaccine is introduced to capture the real impact. Sham case-control or pilot studies before vaccine introduction can be useful in designing case-control VE studies. PMID:24517198

A sham case-control study of effectiveness of DTP-Hib-hepatitis B vaccine against rotavirus acute gastroenteritis in Kenya.

PubMed

Khagayi, Sammy; Tate, Jacqueline E; Onkoba, Reuben; Parashar, Umesh; Odhiambo, Frank; Burton, Deron; Laserson, Kayla; Feikin, Daniel R

2014-02-11

In many GAVI-eligible countries, effectiveness of new vaccines will be evaluated by case-control methodology. To inform the design and assess selection bias of a future case-control study of rotavirus vaccine effectiveness (VE) in western Kenya, we performed a sham case-control study evaluating VE of pentavalent vaccine (DTP-Hib-HepB) against rotavirus acute gastroenteritis (AGE). From ongoing rotavirus surveillance, we defined cases as children 12 weeks to 23 months old with EIA-confirmed rotavirus AGE. We enrolled one community-based and two hospital-based control groups. We collected vaccination status from cards at enrollment, or later in homes, and evaluated VE by logistic regression. We enrolled 91 cases (64 inpatient, 27 outpatient), 252 non-rotavirus AGE facility-based controls (unmatched), 203 non-AGE facility-based controls (age-matched) and 271 community controls (age-matched). Documented receipt of 3 pentavalent doses was 77% among cases and ranged from 81-86% among controls. One percent of cases and 0-2% of controls had no pentavalent doses. The adjusted odds ratio of three versus zero doses for being a case was 3.27 (95% CI 0.01-1010) for community controls and 0.69 (95% CI 0.06-7.75) for non-rotavirus hospital-based AGE controls, translating to VE of -227% and 31%, respectively, with wide confidence intervals. (No facility-based non-AGE controls were unvaccinated.) Similar results were found for ≥2 pentavalent doses and for severe rotavirus AGE. The study showed that it is feasible to carry out a real case control in the study area, but this needs to be done as soon as the vaccine is introduced to capture the real impact. Sham case-control or pilot studies before vaccine introduction can be useful in designing case-control VE studies.

Birth outcomes of male and female patients with infantile hypertrophic pyloric stenosis--a population-based case-control study.

PubMed

Vermes, Gabor; Mátrai, Ákos; Czeizel, Andrew E; Ács, Nándor

2016-01-01

Most of the patients are affected by isolated infantile hypertrophic pyloric stenosis (IHPS) beyond the polygenic predisposition, the other factors in the multifactorial etiology are largely unknown. The main characteristic of IHPS is the robust male predominance, thus the aim of this study was to analyze birth outcomes in males and females whether they are different or not. The study samples included 241 cases with IHPS, 357 matched, and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. The findings of this case-control study confirmed the well-known strong male excess (85.5%). The mean gestational age was somewhat longer and it is associated with a lower rate of preterm births. Mean birth weight did not show significant differences among the study groups, but the rate of low birthweight was higher in cases with IHPS. However, these differences were found only in males. Thus, intrauterine fetal growth restriction is characteristic only for male cases with IHPS. Our study confirmed the well-known obvious male excess of cases with IHPS, but our findings suggest some differences in birth outcomes of male and female cases. Male cases with IHPS had intrauterine fetal growth restriction while females did not. These data may indicate some differences in the pathogenesis of IHPS in males and females.

Case-control studies in diabetes. Do they really use a case-control design?

PubMed

Ramos, Analía; Mendoza, Lilian Cristina; Rabasa, Fernanda; Bolíbar, Ignasi; Puig, Teresa; Corcoy, Rosa

2017-07-01

Studies defined as case-control do not always use this design. We aimed to estimate the frequency of mislabelled case-control studies in published articles in the area of diabetes and to identify the predictors of incorrect labelling. We searched Medline and Web of Science for articles with "diabetes" and "case control" in title and filtered for language (English/Romance) and period (January 2010-December 2014). Inclusion criteria were: (1) statement to use a case-control design in title, (2) to be a final full-length publication and (3) to have original data in the area of diabetes. Three independent reviewers went through titles, looked for full texts and reviewed them. Discrepancies were settled with a fourth reviewer. Expert epidemiologist advice was requested in case of doubt. case-control mislabelling; addressed predictors: publication year, journal impact factor and journal subject. proportion of mislabelled CC articles and assessment of predictors by multivariate logistic regression analysis. We retrieved 362 articles, 251 of them fulfilling inclusion criteria. The proportion of mislabelled CC studies was 43.8% (confidence interval 95% 37.7-50.0%). Most mislabelled studies had a cross-sectional design (82.7%). Predictors of mislabelling were publication year, journal impact factor and journal area. A relevant subset of studies defined as case-control in the area of diabetes correspond to mislabelled cross-sectional studies. Incorrect labelling misleads readers regarding the interpretation of results and the cause-effect hypothesis. Researchers, reviewers and editors should be aware of and commit to settle this issue.

Rural Self Development in India: Two Case Studies. A Curriculum Supplement.

ERIC Educational Resources Information Center

Grant, Thomas N.

Case studies of two, successful, rural, self-development programs in India are presented in this document, which is designed to supplement the study of India in the social studies curriculum. After a brief introduction to India's village system, the two projects are discussed. The first case study presents a water collection system in Bagrunda…

The Use of Case Studies To Teach Educational Psychology: A Comparison with Traditional Instruction. Draft.

ERIC Educational Resources Information Center

Allen, James D.

The use of case studies to teach educational psychology was studied, focusing on their effectiveness in helping students become more reflective in their thinking about the roles of teachers. The effects on content learned, affect and motivation, and performance were studied for students taught through case studies and through traditional…

The Improving Way of Logistics Management in Korean Army

DTIC Science & Technology

2011-03-01

case study , ethnography , phenomenological study , ground theory study and content 18 analysis. The case study deals with a...there are five kinds of qualitative research approaches. To decide which method to be chosen, one should consider the purpose, focus, method of data... qualitative research , case study is good to find the answer when the researcher has no

Case Study: A Step-by-Step Guide to Students Writing Case Studies (and Tools for Novice Case Authors)

ERIC Educational Resources Information Center

Prud'homme-Genereux, Annie

2015-01-01

In experimenting with ways of structuring the assignment and providing guidance to students, the author developed a series of tools that may be of interest to instructors wishing to implement a case-writing assignment in their course. This assignment is more suited for instructors experienced in case writing, as their knowledge of how to design a…

Histological features associated with diagnostic agreement in atypical ductal hyperplasia of the breast: illustrative cases from the B-Path study.

PubMed

Allison, Kimberly H; Rendi, Mara H; Peacock, Sue; Morgan, Tom; Elmore, Joann G; Weaver, Donald L

2016-12-01

This study examined the case-specific characteristics associated with interobserver diagnostic agreement in atypical ductal hyperplasia (ADH) of the breast. Seventy-two test set cases with a consensus diagnosis of ADH from the B-Path study were evaluated. Cases were scored for 17 histological features, which were then correlated with the participant agreement with the consensus ADH diagnosis. Participating pathologists' perceptions of case difficulty, borderline features or whether they would obtain a second opinion were also examined for associations with agreement. Of the 2070 participant interpretations of the 72 consensus ADH cases, 48% were scored by participants as difficult and 45% as borderline between two diagnoses; the presence of both of these features was significantly associated with increased agreement (P < 0.001). A second opinion would have been obtained in 80% of interpretations, and this was associated with increased agreement (P < 0.001). Diagnostic agreement ranged from 10% to 89% on a case-by-case basis. Cases with papillary lesions, cribriform architecture and obvious cytological monotony were associated with higher agreement. Lower agreement rates were associated with solid or micropapillary architecture, borderline cytological monotony, or cases without a diagnostic area that was obvious on low power. The results of this study suggest that pathologists frequently recognize the challenge of ADH cases, with some cases being more prone to diagnostic variability. In addition, there are specific histological features associated with diagnostic agreement on ADH cases. Multiple example images from cases in this test set are provided to serve as educational illustrations of these challenges. © 2016 John Wiley & Sons Ltd.

Performable Case Studies in Ethics Education.

PubMed

Robeson, Richard; King, Nancy M P

2017-09-12

Bioethics education often includes the study of short stories, novels, plays, and films, because such materials present case examples that can highlight relevant issues and questions especially vividly for a wide range of students. In addition, creative writing is widely used in the education of health professional students and in continuing education settings for health professionals. There are very few academic or professional disciplines that do not use case studies, but the case study in dialogic form has not been standard practice for thousands of years. Dramatic arts casuistry-the creation and performance of short case studies designed specifically to raise bioethics issues for discussion-represents an application of literature and the medical humanities that is both unique and uniquely valuable. This essay describes the development and history of a course that has been successfully taught to medical students and graduate bioethics students, in which the class researches, writes, and performs a case study designed to elicit reflection and discussion about a topic and set of bioethics issues of current interest to both academic and general audiences. The model is also suited to the presentation and discussion of existing case studies, both live and via on-demand audio.

Performable Case Studies in Ethics Education

PubMed Central

Robeson, Richard; King, Nancy M. P.

2017-01-01

Bioethics education often includes the study of short stories, novels, plays, and films, because such materials present case examples that can highlight relevant issues and questions especially vividly for a wide range of students. In addition, creative writing is widely used in the education of health professional students and in continuing education settings for health professionals. There are very few academic or professional disciplines that do not use case studies, but the case study in dialogic form has not been standard practice for thousands of years. Dramatic arts casuistry—the creation and performance of short case studies designed specifically to raise bioethics issues for discussion—represents an application of literature and the medical humanities that is both unique and uniquely valuable. This essay describes the development and history of a course that has been successfully taught to medical students and graduate bioethics students, in which the class researches, writes, and performs a case study designed to elicit reflection and discussion about a topic and set of bioethics issues of current interest to both academic and general audiences. The model is also suited to the presentation and discussion of existing case studies, both live and via on-demand audio. PMID:28895903

Analysis of Clinical Cohort Data Using Nested Case-control and Case-cohort Sampling Designs. A Powerful and Economical Tool.

PubMed

Ohneberg, K; Wolkewitz, M; Beyersmann, J; Palomar-Martinez, M; Olaechea-Astigarraga, P; Alvarez-Lerma, F; Schumacher, M

2015-01-01

Sampling from a large cohort in order to derive a subsample that would be sufficient for statistical analysis is a frequently used method for handling large data sets in epidemiological studies with limited resources for exposure measurement. For clinical studies however, when interest is in the influence of a potential risk factor, cohort studies are often the first choice with all individuals entering the analysis. Our aim is to close the gap between epidemiological and clinical studies with respect to design and power considerations. Schoenfeld's formula for the number of events required for a Cox' proportional hazards model is fundamental. Our objective is to compare the power of analyzing the full cohort and the power of a nested case-control and a case-cohort design. We compare formulas for power for sampling designs and cohort studies. In our data example we simultaneously apply a nested case-control design with a varying number of controls matched to each case, a case cohort design with varying subcohort size, a random subsample and a full cohort analysis. For each design we calculate the standard error for estimated regression coefficients and the mean number of distinct persons, for whom covariate information is required. The formula for the power of a nested case-control design and the power of a case-cohort design is directly connected to the power of a cohort study using the well known Schoenfeld formula. The loss in precision of parameter estimates is relatively small compared to the saving in resources. Nested case-control and case-cohort studies, but not random subsamples yield an attractive alternative for analyzing clinical studies in the situation of a low event rate. Power calculations can be conducted straightforwardly to quantify the loss of power compared to the savings in the num-ber of patients using a sampling design instead of analyzing the full cohort.

A methodological review of qualitative case study methodology in midwifery research.

PubMed

Atchan, Marjorie; Davis, Deborah; Foureur, Maralyn

2016-10-01

To explore the use and application of case study research in midwifery. Case study research provides rich data for the analysis of complex issues and interventions in the healthcare disciplines; however, a gap in the midwifery research literature was identified. A methodological review of midwifery case study research using recognized templates, frameworks and reporting guidelines facilitated comprehensive analysis. An electronic database search using the date range January 2005-December 2014: Maternal and Infant Care, CINAHL Plus, Academic Search Complete, Web of Knowledge, SCOPUS, Medline, Health Collection (Informit), Cochrane Library Health Source: Nursing/Academic Edition, Wiley online and ProQuest Central. Narrative evaluation was undertaken. Clearly worded questions reflected the problem and purpose. The application, strengths and limitations of case study methods were identified through a quality appraisal process. The review identified both case study research's applicability to midwifery and its low uptake, especially in clinical studies. Many papers included the necessary criteria to achieve rigour. The included measures of authenticity and methodology were varied. A high standard of authenticity was observed, suggesting authors considered these elements to be routine inclusions. Technical aspects were lacking in many papers, namely a lack of reflexivity and incomplete transparency of processes. This review raises the profile of case study research in midwifery. Midwives will be encouraged to explore if case study research is suitable for their investigation. The raised profile will demonstrate further applicability; encourage support and wider adoption in the midwifery setting. © 2016 John Wiley & Sons Ltd.

First do no harm: is it any longer safe to write case reports?

PubMed

Brown, Laura S

2014-12-01

This article explores the risks to authors and their clients of creating psychological literature based on case studies. The author considers how the events that occurred in Nicole Taus's case might have affected those clients with whom she wrote case studies. Finally, the author analyzes the potential losses to the field should other participants in case studies be at risk of the kind of intrusive invasion of privacy experienced by Taus and calls for the development of ethical principles for psychological science. © The Author(s) 2014.

Television Medical Dramas as Case Studies in Biochemistry

ERIC Educational Resources Information Center

Millard, Julie T.

2009-01-01

Several case studies from popular television medical dramas are described for use in an undergraduate biochemistry course. These cases, which illustrate fundamental principles of biochemistry, are used as the basis for problems that can be discussed further in small groups. Medical cases provide an interesting context for biochemistry with video…

Responsibility and Responsiveness. Case Studies in Further Education.

ERIC Educational Resources Information Center

Kedney, Bob, Ed.; Parkes, David, Ed.

These eight case studies illustrate the capacity of United Kingdom Colleges of Further Education to respond effectively to training needs of local industry and commerce. Case 1 demonstrates shifts across a range of local authority colleges towards provision in the new information technologies and the service industries. Case 2 illustrates a…

Emotion, Engagement, and Case Studies

ERIC Educational Resources Information Center

Herreid, Clyde Freeman; Terry, David R.; Lemons, Paula; Armstrong, Norris; Brickman, Peggy; Ribbens, Eric

2014-01-01

Three college faculty taught large general biology classes using case studies and personal response systems (clickers). Each instructor taught the same eight cases in two different sections, except the questions within the cases differed. In one section the questions were lower order (LO) factual inquiries, and in the other they were largely…

Study on Case Teaching of Financial Management

ERIC Educational Resources Information Center

Che, Zhenghong; Che, Zhengmei

2011-01-01

Case teaching is an efficient teaching method of management. It plays an important role to enhance the students' ability to practice the theory. However, case teaching of financial management has not achieved the expected results. The paper aims to study the importance, characteristics and corresponding methods of case teaching method of financial…

Instructional Design: Case Studies in Communities of Practice

ERIC Educational Resources Information Center

Keppell, Michael, Ed.

2007-01-01

"Instructional Design: Case Studies in Communities of Practice" documents real-world experiences of instructional designers and staff developers who work in communities of practice. "Instructional Design: Case Studies in Communities of Practice" explains the strategies and heuristics used by instructional designers when working…

Case Studies: Improving Environmental Performance and Economic Prosperity at Ports and in Near-Port Communities

EPA Pesticide Factsheets

Case Study links for improving environmental performance and economic prosperity at ports and in near-port communities. Case studies on equipment upgrades, jobs and benefits, land use and transportation, port-community engagement, and citizen science.

Patriot War and the Fenian Raids: Case Studies in Border Security on the U.S. Canada Border in the Nineteenth Century

DTIC Science & Technology

2017-06-09

THE PATRIOT WAR AND THE FENIAN RAIDS: CASE STUDIES IN BORDER SECURITY ON THE U.S.-CANADA BORDER IN THE NINETEENTH CENTURY...3. DATES COVERED (From - To) AUG 2016 – JUN 2017 4. TITLE AND SUBTITLE The Patriot War and the Fenian Raids: Case Studies in Border Security on ...nineteenth century. The Patriot War and Fenian Raids are examined as case studies on the same border occurring roughly thirty years apart. The

Best practices in intercultural health: five case studies in Latin America.

PubMed

Mignone, Javier; Bartlett, Judith; O'Neil, John; Orchard, Treena

2007-09-05

The practice of integrating western and traditional indigenous medicine is fast becoming an accepted and more widely used approach in health care systems throughout the world. However, debates about intercultural health approaches have raised significant concerns. This paper reports findings of five case studies on intercultural health in Chile, Colombia, Ecuador, Guatemala, and Suriname. It presents summary information on each case study, comparatively analyzes the initiatives following four main analytical themes, and examines the case studies against a series of the best practice criteria.

Cost Management in a Tactical Environment: A Case Study of the 316th Expeditionary Support Command (ESC) in Iraq, 2007-2008

DTIC Science & Technology

2010-06-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA MBA PROFESSIONAL REPORT Cost Management in a Tactical Environment: A Case Study of...SUBTITLE Cost Management in a Tactical Environment: A Case Study of the 316th Expeditionary Support Command (ESC) in Iraq, 2007–2008 6. AUTHOR(S...This project provides a case study of the 316th ESC, which may begin to fill that void. The 316th ESC’s staff forecasted future consumption

Variables affecting the financial viability of your practice: a case study.

PubMed

Binderman, J

2001-01-01

Utilizing the discussion of variables affecting practice financial viability, a case study is considered. The case study reveals the relative impact multiple variables have upon the bottom line, including: practice capacity, percentage of capitation, and fee-for-service in the practice, as well as patient visit rates and patient churning. This article presents basic financial information through a case study model, utilizing a series of worksheets that can be adapted to any practice situation to encourage improved financial viability.

A review of published research on adult dissociative identity disorder: 2000-2010.

PubMed

Boysen, Guy A; VanBergen, Alexandra

2013-01-01

The purpose of this study was to assess the scientific and etiological status of dissociative identity disorder (DID) by examining cases published from 2000 to 2010. In terms of scientific status, DID is a small but ongoing field of study. The review yielded 21 case studies and 80 empirical studies, presenting data on 1171 new cases of DID. A mean of 9 articles, each containing a mean of 17 new cases of DID, emerged each year. In terms of etiological status, many of the central criticisms of the disorder's validity remain unaddressed. Most cases of DID emerged from a small number of countries and clinicians. In addition, documented cases occurring outside treatment were almost nonexistent. Finally, people simulating DID in the laboratory were mostly indistinguishable from individuals with DID. Overall, DID is still a topic of study, but the research lacks the productivity and focus needed to resolve ongoing controversies surrounding the disorder.

Clinical Case Studies in Psychoanalytic and Psychodynamic Treatment

PubMed Central

Willemsen, Jochem; Della Rosa, Elena; Kegerreis, Sue

2017-01-01

This manuscript provides a review of the clinical case study within the field of psychoanalytic and psychodynamic treatment. The method has been contested for methodological reasons and because it would contribute to theoretical pluralism in the field. We summarize how the case study method is being applied in different schools of psychoanalysis, and we clarify the unique strengths of this method and areas for improvement. Finally, based on the literature and on our own experience with case study research, we come to formulate nine guidelines for future case study authors: (1) basic information to include, (2) clarification of the motivation to select a particular patient, (3) information about informed consent and disguise, (4) patient background and context of referral or self-referral, (5) patient's narrative, therapist's observations and interpretations, (6) interpretative heuristics, (7) reflexivity and counter-transference, (8) leaving room for interpretation, and (9) answering the research question, and comparison with other cases. PMID:28210235

Combining matched and unmatched control groups in case-control studies.

PubMed

le Cessie, Saskia; Nagelkerke, Nico; Rosendaal, Frits R; van Stralen, Karlijn J; Pomp, Elisabeth R; van Houwelingen, Hans C

2008-11-15

Multiple control groups in case-control studies are used to control for different sources of confounding. For example, cases can be contrasted with matched controls to adjust for multiple genetic or unknown lifestyle factors and simultaneously contrasted with an unmatched population-based control group. Inclusion of different control groups for a single exposure analysis yields several estimates of the odds ratio, all using only part of the data. Here the authors introduce an easy way to combine odds ratios from several case-control analyses with the same cases. The approach is based upon methods used for meta-analysis but takes into account the fact that the same cases are used and that the estimated odds ratios are therefore correlated. Two ways of estimating this correlation are discussed: sandwich methodology and the bootstrap. Confidence intervals for the pooled estimates and a test for checking whether the odds ratios in the separate case-control studies differ significantly are derived. The performance of the method is studied by simulation and by applying the methods to a large study on risk factors for thrombosis, the MEGA Study (1999-2004), wherein cases with first venous thrombosis were included with a matched control group of partners and an unmatched population-based control group.

The Effectiveness of Lecture-Integrated, Web-Supported Case Studies in Large Group Teaching

ERIC Educational Resources Information Center

Azzawi, May; Dawson, Maureen M.

2007-01-01

The effectiveness of lecture-integrated and web-supported case studies in supporting a large and academically diverse group of undergraduate students was evaluated in the present study. Case studies and resource (web)-based learning were incorporated as two complementary interactive learning strategies into the traditional curriculum. A truncated…

Designing a Gamified Online Course: A Preliminary Case Study

ERIC Educational Resources Information Center

Grabowski, Jeremiah Stanley

2017-01-01

This exploratory case study delves into the instructional design of a gamified online course. The study focuses on how the professor incorporated game elements into a graduate-level online course. Participants in the gamified course were pre- and in-service mathematics teachers. The qualitative case study used two sources of data, an interview…

Engaging Engineering Students in Geoscience through Case Studies and Active Learning

ERIC Educational Resources Information Center

Holley, Elizabeth A.

2017-01-01

This study reports on a case study-based curricular intervention designed to help undergraduate engineering students make connections between geoscience and its applications. Teaching through case studies resulted in a measurable and significant improvement in the confidence that students had in their ability to apply geoscience concepts in an…

Using MultiMedia Content to Present Business Ethics: An Empirical Study

ERIC Educational Resources Information Center

Stanwick, Peter A.

2010-01-01

The purpose of this study is to empirically examine whether presenting a multimedia case study enhances the learning experience of students in an undergraduate management class. A questionnaire was administered before and after the presentation of the case study and the results showed that the multimedia case did indeed enhance the learning…

Case study #3 -- severe scaling of an interstate bridge deck, and Potentially reactive carbonate aggregates, progress report #6 (partial): an example of bridge deterioration promoted by alkali-carbonate reaction.

DOT National Transportation Integrated Search

1971-01-01

The project designated "Concrete Durability Studies" comprises case studies of unusual durability, either in kind or extent. These case studies are directed toward situations in which appearances suggest materials or construction rather than structur...

World Perspective Case Descriptions on Educational Programs for Adults: Czechoslovakia.

ERIC Educational Resources Information Center

Skoda, Kamil; Hartl, Pavel

This document contains two case studies of Czechoslovakian adult education: (1) Czechoslovakian Adult Education (Skoda) and (2) the House of Culture and Its Function in Adult Education (Hartl). Each study begins with a "face sheet" on which is recorded basic information about the entity studied and the case study itself. About half of…

Analysis of Alternatives (AoA) Process Improvement Study

DTIC Science & Technology

2016-12-01

stakeholders, and mapped the process activities and durations. We tasked the SAG members with providing the information required on case studies and...are the expected time saves/cost/risk of any changes? (3) Utilization of case studies for both “good” and “challenged” AoAs to identify lessons...16 4 CASE STUDIES

A Framework for Analysis of Case Studies of Reading Lessons

ERIC Educational Resources Information Center

Carlisle, Joanne F.; Kelcey, Ben; Rosaen, Cheryl; Phelps, Geoffrey; Vereb, Anita

2013-01-01

This paper focuses on the development and study of a framework to provide direction and guidance for practicing teachers in using a web-based case studies program for professional development in early reading; the program is called Case Studies Reading Lessons (CSRL). The framework directs and guides teachers' analysis of reading instruction by…

Development and Formative Evaluation of Multimedia Case Studies for Instructional Design and Technology Students

ERIC Educational Resources Information Center

Sugar, William

2014-01-01

This study describes the development of three case studies that included a combination of multimedia production and instructional design skills within a particular setting. These case studies incorporated real-life incidents from 47 professional instructional designers. These instructional designers described a total of 146 activities involving…

The Budget Process in Parks and Recreation. A Case Study Manual.

ERIC Educational Resources Information Center

Kelsey, Craig; Gray, Howard

This case study manual, designed for undergraduate or graduate students studying the area of parks and recreation fiscal management, considers the practical, critical skills of budgeting techniques. The manual deals with the most common budgeting styles in a step-by-step approach with case study exercises. Each chapter includes an introduction to…

Online Case Studies as a Professional Development Opportunity for Teachers of Elementary Reading

ERIC Educational Resources Information Center

Vereb, Anita; Carlisle, Joanne F.; Mihocko-Bowling, Emily

2015-01-01

This study explores teachers' response to a professional development program called Case Studies of Reading Lessons (CSRL) that uses case studies of reading instruction to provide opportunities for elementary teachers to learn to analyze features that affect the quality of reading lessons. One important question is whether analyzing others'…

A Mixed Methods Sampling Methodology for a Multisite Case Study

ERIC Educational Resources Information Center

Sharp, Julia L.; Mobley, Catherine; Hammond, Cathy; Withington, Cairen; Drew, Sam; Stringfield, Sam; Stipanovic, Natalie

2012-01-01

The flexibility of mixed methods research strategies makes such approaches especially suitable for multisite case studies. Yet the utilization of mixed methods to select sites for these studies is rarely reported. The authors describe their pragmatic mixed methods approach to select a sample for their multisite mixed methods case study of a…

Use of Case Studies for Stimulating Thinking and Learning.

ERIC Educational Resources Information Center

Zeakes, Samuel J.

Noting that a case-study approach can stimulate student thinking and learning, this paper describes how students in a writing-intensive course on parasitology wrote brief medical case studies of parasites already studied for other students to read, evaluate, and identify the parasite. The paper presents a brief description of the course, an…

The effectiveness of collaborative care for people with memory problems in primary care: results of the CAREDEM case management modelling and feasibility study.

PubMed

Iliffe, Steve; Waugh, Amy; Poole, Marie; Bamford, Claire; Brittain, Katie; Chew-Graham, Carolyn; Fox, Chris; Katona, Cornelius; Livingston, Gill; Manthorpe, Jill; Steen, Nick; Stephens, Barbara; Hogan, Vanessa; Robinson, Louise

2014-08-01

People with dementia and their families need support in different forms, but currently services are often fragmented with variable quality of care. Case management offers a way of co-ordinating services along the care pathway and therefore could provide individualised support; however, evidence of the effectiveness of case management for dementia is inconclusive. To adapt the intervention used in a promising case management project in the USA and test its feasibility and acceptability in English general practice. In work package 1, a design group of varied professionals, with a carer and staff from the voluntary sector, met six times over a year to identify the skills and personal characteristics required for case management; protocols from the US study were adapted for use in the UK. The feasibility of recruiting general practices and patient-carer dyads and of delivering case management were tested in a pilot study (work package 2). An embedded qualitative study explored stakeholder views on study procedures and case management. Four general practices, two in the north-east of England (Newcastle) one in London and one in Norfolk, took part in a feasibility pilot study of case management. Community-dwelling people with dementia and their carers who were not already being case managed by other services. A social worker shared by the two practices in the north-east and practice nurses in the other two practices were trained to deliver case management. We aimed to recruit 11 people with dementia from each practice who were not already being case managed. Numbers of people with dementia and their carers recruited, numbers and content of contacts, needs identified and perceptions of case management among stakeholders. Recruitment of practices and patients was slow and none of the practices achieved its recruitment target. It took more than 6 months to recruit a total of 28 people with dementia. Practice Quality and Outcome Framework registers for dementia contained only 60% of the expected number of people, most living in care homes. All stakeholders were positive about the potential of case management; however, only one of the four practices achieved a level of case management activity that might have influenced patient and carer outcomes. Case managers' activity levels were not related solely to time available for case management. Delivery of case management was hindered by limited clarity about the role, poor integration with existing services and a lack of embeddedness within primary care. There were discrepancies between case manager and researcher judgements about need, and evidence of a high threshold for acting on unmet need. The practice nurses experienced difficulties in ring-fencing case management time. The model of case management developed and evaluated in this feasibility study is unlikely to be sustainable in general practice under current conditions and in our view it would not be appropriate to attempt a definitive trial of this model. This study could inform the development of a case management role with a greater likelihood of impact. Different approaches to recruiting and training case managers, and identifying people with dementia who might benefit from case management, are needed, as is exploration of the scale of need for this type of working. Current Controlled Trials ISRCTN74015152. This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 52. See the NIHR Journals Library website for further project information.

Case studies approach for an undergraduate astrobiology course

NASA Astrophysics Data System (ADS)

Burko, Lior M.; Enger, Sandra

2013-04-01

Case studies is a well known and widely used method in law schools, medical schools, and business schools, but relatively little used in physics or astronomy courses. We developed an astrobiology course based strongly on the case studies approach, and after teaching it first at the University of Alabama in Huntsville, we have adapted it and are now teaching it at Alabama A&M University, a HBCU. The case studies approach uses several well tested and successful teaching methods - including group work, peer instruction, current interest topics, just-in-time teaching, &c. We have found that certain styles of cases are more popular among students than other styles, and will revise our cases to reflect such student preferences. We chose astrobiology -- an inherently multidisciplinary field -- because of the popularity of the subject matter, its frequent appearance in the popular media (news stories about searches for life in the universe, the discovery of Earth-like exoplanets, etc, in addition to SciFi movies and novels), and the rapid current progress in the field. In this talk we review briefly the case studies method, the styles of cases used in our astrobiology course, and student response to the course as found in our assessment analysis.

Facilitating Case Studies in Massage Therapy Clinical Education

PubMed Central

Baskwill, Amanda

2013-01-01

The integration of evidence into reflective health care practice has been on the rise in recent years and is a phenomenon that has affected all health care professions, including massage therapy. Clinical case studies are a research design that follows one patient or subject, making the studies ideal for use in clinical practice. They are valuable for communicating information from clinical practice to the broader community. Case studies have face validity that may be more valuable to individual practitioners than homogeneous randomized controlled trials, as the practitioner may recognize a complex patient in the case report. At Humber College, Student Massage Therapists (SMTs) create, conduct, and communicate results of a clinical case study prior to graduation. This article describes the process and experience. PMID:23730397

Teaching astronomy with case studies

NASA Astrophysics Data System (ADS)

Slater, Timothy F.

2015-11-01

Breaking the students into small, collaborative learning groups to solve a meaningful task together is one of the most successful and fully evaluated teaching techniques implemented over the last century. Although there are many ways to accomplish small group learning, a long-standing and consistently successful collaborative class activity is to use the case study teaching strategy. The use of case studies is common in medical schools and law schools, but not so common in the teaching of astronomy. Case studies create meaningful conversations among students and with the professor by focusing on life-like dilemmas to be solved. Case study tasks ask audience members to synthesize several ideas or evaluate scenarios that have not been explicitly presented to them in the lecture or in available readings.

An Approach to Using Toxicogenomic Data in US EPA Human ...

EPA Pesticide Factsheets

This draft report is a description of an approach to evaluate genomic data for use in risk assessment and a case study to illustrate the approach. The dibutyl phthalate (DBP) case study example focuses on male reproductive developmental effects and the qualitative application of the available genomic data. The case study presented in this draft document is a separate activity from any of the ongoing IRIS human health assessments for the phthalates. This draft report is a description of an approach to evaluate genomic data for use in risk assessment and a case study to illustrate the approach. The dibutyl phthalate (DBP) case study example focuses on male reproductive developmental effects and the qualitative application of the available genomic data.

Addressing trend-related changes within cumulative effects studies in water resources planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canter, L.W., E-mail: envimptr@aol.com; Chawla, M.K.; Swor, C.T.

2014-01-15

Summarized herein are 28 case studies wherein trend-related causative physical, social, or institutional changes were connected to consequential changes in runoff, water quality, and riparian and aquatic ecological features. The reviewed cases were systematically evaluated relative to their identified environmental effects; usage of analytical frameworks, and appropriate models, methods, and technologies; and the attention given to mitigation and/or management of the resultant causative and consequential changes. These changes also represent important considerations in project design and operation, and in cumulative effects studies associated therewith. The cases were grouped into five categories: institutional changes associated with legislation and policies (seven cases);more » physical changes from land use changes in urbanizing watersheds (eight cases); physical changes from land use changes and development projects in watersheds (four cases); physical, institutional, and social changes from land use and related policy changes in river basins (three cases); and multiple changes within a comprehensive study of land use and policy changes in the Willamette River Basin in Oregon (six cases). A tabulation of 110 models, methods and technologies used in the studies is also presented. General observations from this review were that the features were unique for each case; the consequential changes were logically based on the causative changes; the analytical frameworks provided relevant structures for the studies, and the identified methods and technologies were pertinent for addressing both the causative and consequential changes. One key lesson was that the cases provide useful, “real-world” illustrations of the importance of addressing trend-related changes in cumulative effects studies within water resources planning. Accordingly, they could be used as an “initial tool kit” for addressing trend-related changes.« less

Short-term effects of floods on Japanese encephalitis in Nanchong, China, 2007-2012: A time-stratified case-crossover study.

PubMed

Zhang, Feifei; Liu, Zhidong; Zhang, Caixia; Jiang, Baofa

2016-09-01

This time-stratified case-crossover study aimed to quantify the impact of floods on daily Japanese encephalitis (JE) cases from 2007 to 2012 in Nanchong city of Sichuan Province, China. Using conditional logistic regression analysis, we calculated the odds ratios (ORs) and 95% confidence intervals (CIs) at different lagged days, adjusting for daily average temperature (AT) and daily average relative humidity (ARH). A total of 370 JE cases were notified during the study period, with the median patient age being 4.2years. The seasonal pattern of JE cases clustered in July and August during the study period. Floods were significantly associated with an increased number of JE cases from lag 23 to lag 24, with the strongest lag effect at lag 23 (OR=2.00, 95% CI: 1.14-3.52). Similarly, AT and ARH were positively associated with daily JE cases from lag 0 to lag 8 and from lag 0 to lag 9, respectively. Floods, with AT and ARH, can be used to forecast JE outbreaks in the study area. Based on the results of this study, recommendations include undertaking control measures before the number of cases increases, especially for regions with similar geographic, climatic, and socio-economic conditions as those in the study area. Copyright © 2016 Elsevier B.V. All rights reserved.

[Clinical evaluation of propess for induction of term pregnancy].

PubMed

Gai, Ming-ying; Zhang, Jian-ping; Li, Yang; Han, Hong-jing; Yang, Jian-qiu; Wang, Shan-mi; Su, Qi-feng; Wu, Lian-fang

2003-04-01

To explore the efficacy and safety of continuously released prostaglandin E(2) (PGE(2)) suppository-propess used for induction of term pregnancy. A multicenter, prospective, case control clinical study was carried out, propess was used in 100 cases as study group, the suppository without PGE(2) was used in 49 cases as control group. The cervical maturity (by Bishop scoring), the time to labor starting, membrane rupture and delivery, the application of oxytocin, ceserean section rate, fetal and neonatal condition were compared between 2 groups after inserting of the suppository. At the same time, side effects caused by propess were investigated. Bishop score was increased >or= 2 points in 93% cases, >or= 3 points in 87% cases in study group, whereas only 4% cases whose Bishop score increased >or= 2 points in control group. The time to labor starting, membrane rupture, and delivery was shortened obviously in study group than that in control group after inserting suppository. The application of oxytocin was much less in study group, cesarean section rate was reduced in study group (32% vs 61%). There was no significant difference between 2 groups in fetal and neonatal conditions. The overstimulation of uterine contraction and mild gastrointestinal tract reaction occurred in 3 cases and 2 cases respectively in study groups. Propess can be used for induction of term pregnancy effectively and safely.

Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray (External Review Draft)

EPA Science Inventory

This draft document presents a case study of engineered nanoscale silver (nano-Ag), focusing on the specific example of nano-Ag as possibly used in disinfectant sprays. This case study is organized around a comprehensive environmental assessment (CEA) framework, which combines a ...

Fuzzy-Set Case Studies

ERIC Educational Resources Information Center

Mikkelsen, Kim Sass

2017-01-01

Contemporary case studies rely on verbal arguments and set theory to build or evaluate theoretical claims. While existing procedures excel in the use of qualitative information (information about kind), they ignore quantitative information (information about degree) at central points of the analysis. Effectively, contemporary case studies rely on…

Case Study: Student-Produced Videos for the Flipped Classroom

ERIC Educational Resources Information Center

Prud'homme-Genereux, Annie

2016-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. This month's issue describes a way of building a library of student-produced videos to use in the flipped classroom.

WWW Case Study Program To Enhance Thinking, Critically and Globally: The Impact of NAFTA on the Apparel Industry.

ERIC Educational Resources Information Center

Frey, Diane K.; Eckman, Molly

1999-01-01

An interactive Web program was developed to present a case study on textile/apparel products for a family and consumer sciences course. Students found the case studies relevant and stimulating for complex thinking. (SK)

Bad Blood.

ERIC Educational Resources Information Center

Fourtner, Ann W.; And Others

1994-01-01

Describes a case study of the Tuskegee Syphilis project to help demonstrate the use of the case study method in instruction. This is one of a series of articles written to stimulate interest in and discussion about the use of the case study method in teaching undergraduate-level science. (ZWH)

A Neuroanatomy Teaching Activity Using Case Studies and Collaboration.

ERIC Educational Resources Information Center

Sheldon, Jane P.

2000-01-01

Describes an activity for use in an introductory psychology course in which students collaborate and apply their neuroanatomy knowledge to three case studies. Provides a table with descriptions of and possible answers for the three case studies and discusses the students' responses. (CMK)

Collaboration in Distance Education. International Case Studies.

ERIC Educational Resources Information Center

Moran, Louise, Ed.; Mugridge, Ian, Ed.

This book contains nine case studies of collaboration in distance education. The case studies focus on such aspects of collaboration in distance education as the following: roles of individual institutional partners; importance of personal relationships; benefits of collaboration to individual partners; conflicts between collaboration and…

SETDA Case Studies 2012

ERIC Educational Resources Information Center

State Educational Technology Directors Association, 2012

2012-01-01

The State Educational Technology Directors Association (SETDA) published a series of case studies from 28 states to showcase examples of how ARRA EETT ("American Recovery and Reinvestment Act of 2009 Enhancing Education Through Technology") grant funds have impacted teaching and learning. SETDA collected data for the case studies through…

The HABP2 G534E Variant Is an Unlikely Cause of Familial Nonmedullary Thyroid Cancer

PubMed Central

Sahasrabudhe, Ruta; Stultz, Jacob; Williamson, John; Lott, Paul; Estrada, Ana; Bohorquez, Mabel; Palles, Claire; Polanco-Echeverry, Guadalupe; Jaeger, Emma; Martin, Lynn; Echeverry, Maria Magdalena; Tomlinson, Ian

2016-01-01

Context: A recent study reported the nonsynonymous G534E (rs7080536, allele A) variant in the HABP2 gene as causal in familial nonmedullary thyroid cancer (NMTC). Objective: The objective of this study was to evaluate the causality of HABP2 G534E in the TCUKIN study, a multicenter population-based study of NMTC cases from the British Isles. Design and Setting: A case-control analysis of rs7080536 genotypes was performed using 2105 TCUKIN cases and 5172 UK controls. Participants: Cases comprised 2105 NMTC cases. Patient subgroups with papillary (n = 1056), follicular (n = 691), and Hürthle cell (n = 86) thyroid cancer cases were studied separately. Controls comprised 5172 individuals from the 1958 Birth Cohort and the National Blood Donor Service study. The controls had previously been genotyped using genome-wide single nucleotide polymorphism arrays by the Wellcome Trust Case Control Consortium study. Outcome Measures: Association between HABP2 G534E (rs7080536A) and NMTC risk was evaluated using logistic regression. Results: The frequency of the HABP2 G534E was 4.2% in cases and 4.6% in controls. We did not detect an association between this variant and NMTC risk (odds ratio [OR] = 0.896; 95% confidence interval, 0.746–1.071; P = .233). We also failed to detect an association between the HABP2 G534E and cases with papillary (1056 cases; G534E frequency = 3.5%; OR = 0.74; P = .017), follicular (691 cases; G534E frequency = 4.7%; OR = 1.00; P = 1.000), or Hürthle cell (86 cases; G534E frequency = 6.3%; OR = 1.40; P = .279) histology. Conclusions: We found that HABP2 G534E is a low-to-moderate frequency variant in the British Isles and failed to detect an association with NMTC risk, independent of histological type. Hence, our study does not implicate HABP2 G534E or a correlated polymorphism in familial NMTC, and additional data are required before using this variant in NMTC risk assessment. PMID:26691890

The HABP2 G534E variant is an unlikely cause of familial non-medullary thyroid cancer.

PubMed

Sahasrabudhe, Ruta; Stultz, Jacob; Williamson, John; Lott, Paul; Estrada, Ana; Bohorquez, Mabel; Palles, Claire; Polanco-Echeverry, Guadalupe; Jaeger, Emma; Martin, Lynn; Magdalena Echeverry, Maria; Tomlinson, Ian; Carvajal-Carmona, Luis G

2016-03-01

A recent study reported the non-synonymous G534E (rs7080536, allele A) variant in the HABP2 gene as causal in familial non-medullary thyroid cancer (NMTC). The objective of this study was to evaluate the causality of HABP2 G534E in the TCUKIN study, a multi-center population based study of NMTC cases from the British Isles. A case-control analysis of rs7080536 genotypes was performed using 2,105 TCUKIN cases and 5,172 UK controls. Cases comprised 2,105 NMTC cases. Patients sub-groups with papillary (N=1,056), follicular (N=691) and Hurthle cell (N=86) TC cases were studied separately. Controls comprised 5,172 individuals from the 1958 Birth Cohort (58C) and the National Blood Donor Service (NBS) study. The controls had previously been genotyped using genome-wide SNP arrays by the Wellcome Trust Case Control Consortium study. Measures: Association between HABP2 G534E (rs7080536A) and NMTC risk was evaluated using logistic regression. The frequency of HABP2 G534E was 4.2% in cases and 4.6% in controls. We did not detect an association between this variant and NMTC risk (OR=0.896, 95% CI: 0.746-1.071, P=0.233). We also failed to detect an association between HABP2 G534E and cases with papillary (1056 cases, G534E frequency= 3.5%, OR=0.74, P=0.017), follicular (691 cases, G534E frequency= 4.7%, OR=1.00, P=1.000) or Hurthle cell (86 cases, G534E frequency= 6.3%, OR=1.40, P=0.279) histology. We found that HABP2 G534E is a low-to-moderate frequency variant in the British Isles and failed to detect an association with NMTC risk, independent of histological type. Hence, our study does not implicate HABP2 G534E or a correlated polymorphism in familial NMTC and additional data are required before using this variant in NMTC risk assessment.

Effect of Case Studies on Primary School Teaching Students' Attitudes toward Chemistry Lesson

ERIC Educational Resources Information Center

Ayyildiz, Yildizay; Tarhan, Leman

2012-01-01

The purpose of this study was to investigate the effect of case studies on Primary School Teaching students' attitudes toward chemistry lesson. The study was conducted on 63 freshmen from Department of Primary School Teaching at a university in Turkey. The students were taught using case studies about the subjects of Properties and States of…

Promoting Physical Activity in Girls: A Case Study of One School's Success.

ERIC Educational Resources Information Center

Felton, Gwen; Saunders, Ruth P.; Ward, Dianne S.; Dishman, Rod K.; Dowda, Marsha; Pate, Russell R.

2005-01-01

This case study profiles one of 24 high schools that participated in a school-based, NIH-funded study to increase physical activity among high school girls. The case study school was one of 12 randomly assigned to the intervention group. The study intervention was based on the premise that a successful intervention is developed and tailored by…

Finding a Balance: Fifteen Institutional Case Studies on the Relationship between Part-Time Work and Advanced Level Study. Report.

ERIC Educational Resources Information Center

Hodgson, Ann, Ed.; Spours, Ken, Ed.

This document presents and discusses case studies that examined the relationship between part-time employment and advanced level study at 15 schools in Essex, England. "Foreword" (David Jones) provides a brief overview of the project. "Finding a Balance--Fifteen Institutional Case Studies on the Relationship between Part-time Work…

Investigation of Geobase Implementation Issues: Case Study of Information Resource Management

DTIC Science & Technology

2004-03-01

case study , ethnography , phenomenological study , and grounded theory . “Of...all the research designs [described] … a grounded theory study is the one that is least likely to begin from a 40 Use this approach if...the treatments explained, the case study method best matches the objectives of this research (Leedy & Ormrod, 2001). Yin’s criteria for

Primary School Teachers' Perception on Parental Involvement: A Quliatative Case Study

ERIC Educational Resources Information Center

Aslan, Dolgun

2016-01-01

The purpose of this study is to highlight the opinions of teachers with regard to the approaches of parental involvement in school. A case study design was used in this study conducted that is employed in studies of a qualitative nature. In the "case" under research, there was an attempt to determine the opinions of teachers regarding…

Zika virus disease, microcephaly and Guillain-Barré syndrome in Colombia: epidemiological situation during 21 months of the Zika virus outbreak, 2015-2017.

PubMed

Méndez, Nelson; Oviedo-Pastrana, Misael; Mattar, Salim; Caicedo-Castro, Isaac; Arrieta, German

2017-01-01

The Zika virus disease (ZVD) has had a huge impact on public health in Colombia for the numbers of people affected and the presentation of Guillain-Barre syndrome (GBS) and microcephaly cases associated to ZVD. A retrospective descriptive study was carried out, we analyze the epidemiological situation of ZVD and its association with microcephaly and GBS during a 21-month period, from October 2015 to June 2017. The variables studied were: (i) ZVD cases, (ii) ZVD cases in pregnant women, (iii) laboratory-confirmed ZVD in pregnant women, (iv) ZVD cases associated with microcephaly, (v) laboratory-confirmed ZVD associated with microcephaly, and (vi) ZVD associated to GBS cases. Average number of cases, attack rates (AR) and proportions were also calculated. The studied variables were plotted by epidemiological weeks and months. The distribution of ZVD cases in Colombia was mapped across the time using Kernel density estimator and QGIS software; we adopted Kernel Ridge Regression (KRR) and the Gaussian Kernel to estimate the number of Guillain Barre cases given the number of ZVD cases. One hundred eight thousand eighty-seven ZVD cases had been reported in Colombia, including 19,963 (18.5%) in pregnant women, 710 (0.66%) associated with microcephaly (AR, 4.87 cases per 10,000 live births) and 453 (0.42%) ZVD associated to GBS cases (AR, 41.9 GBS cases per 10,000 ZVD cases). It appears the cases of GBS increased in parallel with the cases of ZVD, cases of microcephaly appeared 5 months after recognition of the outbreak. The kernel density map shows that throughout the study period, the states most affected by the Zika outbreak in Colombia were mainly San Andrés and Providencia islands, Casanare, Norte de Santander, Arauca and Huila. The KRR shows that there is no proportional relationship between the number of GBS and ZVD cases. During the cross validation, the RMSE achieved for the second order polynomial kernel, the linear kernel, the sigmoid kernel, and the Gaussian kernel are 9.15, 9.2, 10.7, and 7.2 respectively. This study updates the epidemiological analysis of the ZVD situation in Colombia describes the geographical distribution of ZVD and shows the functional relationship between ZVD cases and GBS.

Promoting Creativity in International Business Education: A Protocol for Student-Constructed Cases

ERIC Educational Resources Information Center

Riordan, Diane A.; Sullivan, M. Cathy; Fink, Danny

2003-01-01

Case studies, including "archival cases," "documentary cases," "living cases," and "learner-generated cases," are popular teaching methods in the international business curriculum. In this paper we present a protocol for student-constructed cases, an extension of the learner-generated case, and provide an example using foreign currency exchange…

Morphological changes in carotid arteries in stroke cases.

PubMed

Thapa, Guna Bahadur; Sundas, Alin; Rauniyar, Raj Kumar

2013-01-01

Majority of stroke is due to ischemic infarction and occurs in carotid artery territory. The extra cranial parts of carotid arteries are the common sites for the atherosclerotic plaque formation. Ultrasonography is the first line of investigation for screening of the carotid artery diseases to localize and characterize the plaques. Objective was to study the morphological changes in extra cranial part of carotid arteries in cases of ischemic infarction using Ultrasonography. It was an institution based prospective study and convenience sampling method was used. Computed Tomography proven ischemic infarct, lacunar infarction and transient ischemic infarction cases were included in the study. Fifty four cases were included in the study. Mean of Intimo-medial Complex Thickness was 0.89 mm and 0.88 mm in right and left side respectively. Sixty five percent cases had plaque in extra cranial part of carotid artery. Ninety three percent of plaque was found in and adjacent to the carotid bulb region. Ipsilateral plaque was found in 76% and 65% cases on right and left side respectively. Fifty three percent of cases had soft plaque. Majority of cases had less than 50% narrowing of the lumen diameter in term of cross-sectional area due to plaque. Thirteen (24%) cases had plaque in internal carotid artery. Carotid ultrasound can be used for screening of the asymptomatic but high-risk cases and following up of the symptomatic cases to plan for necessary management as required.

Analysis of risk factors for schizophrenia with two different case definitions: a nationwide register-based external validation study.

PubMed

Sørensen, Holger J; Larsen, Janne T; Mors, Ole; Nordentoft, Merete; Mortensen, Preben B; Petersen, Liselotte

2015-03-01

Different case definitions of schizophrenia have been used in register based research. However, no previous study has externally validated two different case definitions of schizophrenia against a wide range of risk factors for schizophrenia. We investigated hazard ratios (HRs) for a wide range of risk factors for ICD-10 DCR schizophrenia using a nationwide Danish sample of 2,772,144 residents born in 1955-1997. We compared one contact only (OCO) (the case definition of schizophrenia used in Danish register based studies) with two or more contacts (TMC) (a case definition of at least 2 inpatient contacts with schizophrenia). During the follow-up, the OCO definition included 15,074 and the TMC 7562 cases; i.e. half as many. The TMC case definition appeared to select for a worse illness course. A wide range of risk factors were uniformly associated with both case definitions and only slightly higher risk estimates were found for the TMC definition. Choosing at least 2 inpatient contacts with schizophrenia (TMC) instead of the currently used case definition would result in almost similar risk estimates for many well-established risk factors. However, this would also introduce selection and include considerably fewer cases and reduce power of e.g. genetic studies based on register-diagnosed cases only. Copyright © 2015 Elsevier B.V. All rights reserved.

Case-control vaccine effectiveness studies: Data collection, analysis and reporting results.

PubMed

Verani, Jennifer R; Baqui, Abdullah H; Broome, Claire V; Cherian, Thomas; Cohen, Cheryl; Farrar, Jennifer L; Feikin, Daniel R; Groome, Michelle J; Hajjeh, Rana A; Johnson, Hope L; Madhi, Shabir A; Mulholland, Kim; O'Brien, Katherine L; Parashar, Umesh D; Patel, Manish M; Rodrigues, Laura C; Santosham, Mathuram; Scott, J Anthony; Smith, Peter G; Sommerfelt, Halvor; Tate, Jacqueline E; Victor, J Chris; Whitney, Cynthia G; Zaidi, Anita K; Zell, Elizabeth R

2017-06-05

The case-control methodology is frequently used to evaluate vaccine effectiveness post-licensure. The results of such studies provide important insight into the level of protection afforded by vaccines in a 'real world' context, and are commonly used to guide vaccine policy decisions. However, the potential for bias and confounding are important limitations to this method, and the results of a poorly conducted or incorrectly interpreted case-control study can mislead policies. In 2012, a group of experts met to review recent experience with case-control studies evaluating vaccine effectiveness; we summarize the recommendations of that group regarding best practices for data collection, analysis, and presentation of the results of case-control vaccine effectiveness studies. Vaccination status is the primary exposure of interest, but can be challenging to assess accurately and with minimal bias. Investigators should understand factors associated with vaccination as well as the availability of documented vaccination status in the study context; case-control studies may not be a valid method for evaluating vaccine effectiveness in settings where many children lack a documented immunization history. To avoid bias, it is essential to use the same methods and effort gathering vaccination data from cases and controls. Variables that may confound the association between illness and vaccination are also important to capture as completely as possible, and where relevant, adjust for in the analysis according to the analytic plan. In presenting results from case-control vaccine effectiveness studies, investigators should describe enrollment among eligible cases and controls as well as the proportion with no documented vaccine history. Emphasis should be placed on confidence intervals, rather than point estimates, of vaccine effectiveness. Case-control studies are a useful approach for evaluating vaccine effectiveness; however careful attention must be paid to the collection, analysis and presentation of the data in order to best inform evidence-based vaccine policies. Published by Elsevier Ltd.

[Characteristics of cases hospitalized for severe pandemic (H1N1) 2009 in Catalonia].

PubMed

Godoy, Pere; Rodés, Anna; Alvarez, Josep; Camps, Neus; Barrabeig, Irene; Sala, María Rosa; Minguell, Sofía; Lafuente, Sarah; Pumarola, Tomás; Domínguez, Angela; Plasència, Antoni

2011-01-01

Influenza pandemics may cause more severe cases. The objective was to determine the characteristics of hospitalized severe cases of pandemic influenza in Catalonia and to study risk factors for admission to intensive care unit (ICU). A prospective epidemiologic study of new cases of pandemic influenza hospitalized by their severity between June 2009 and May 2010. Hospitals were asked to declare laboratory confirmed pandemic influenza cases that met the case specific case definition for severe case. A standardized epidemiological survey was conducted to collect information on demographics, clinical characteristics, risk factors, treatment and outcome. Differences between the cases in ICU compared to other severe cases were studied with the odds ratio (OR), which were adjusted using a logistic regression model. We detected total of 773 pandemic influenza (H1N1) 2009 severe cases; 465 (60.2%) of them had at least one risk factor and the most prevalent were: pregnancy 19 (13%), asthma 87 (12%), chronic obstructive pulmonary disease 87 (11.4%) and heart disease 80 (10.5%). Required admission to ICU 293 patients (37.9%). Factors associated with ICU admission were obesity BMI>40 (adjusted OR = 2.5, 95% CI 1.4-4.5) and chronic liver disease (adjusted OR = 2.3, 95% CI 1.1-4.8). This study confirms the high prevalence of pregnancy, chronic respiratory diseases, diabetes and obesity among pandemic influenza severe cases. Obesity acts as a risk factor for ICU admission and should therefore be considered as an indicator for influenza vaccination.

[Correlation between typing of peripheral neuroblastic tumors and prognosis: a clinicopathologic study of 135 cases].

PubMed

YIN, Min-zhi; ZHANG, Zhong-de; MA, Jing; SHEN, Ping; CHEN, Jie-feng; ZHANG, Hui-zhen

2011-03-01

To study the clinicopathologic characteristics of peripheral neuroblastic tumors and to investigate the prognostic significance of International Neuroblastoma Pathology Classification (INPC). One hundred and thirty-five cases of peripheral neuroblastic tumors encountered in Shanghai Children's Medical Center were enrolled into the study. All the cases were classified according to INPC and International Neuroblastoma Staging System (INSS). The follow-up data were analyzed. The consensus diagnoses of the 135 cases were as follows: 80 cases (59.2%) of neuroblastoma, 24 cases (17.8%) of ganglioneuroblastoma, intermixed, 17 cases (12.6%) of ganglioneuroma and 14 cases (10.4%) of ganglioneuroblastoma, nodular. The cases were subdivided into 2 subgroups: favorable histology (number = 90, 66.7%) and unfavorable histology (number = 45, 33.3%). According to INSS, the number of cases in stages I, II, III and IV was 22 (16.3%), 24 (17.8%), 34 (25.2%) and 55 (40.7%), respectively. The survival of peripheral neuroblastic tumors correlated with histologic diagnosis, INPC and INSS (P < 0.05). Diagnostic categorization of peripheral neuroblastic tumors according to INPC is of prognostic value.

Does case misclassification threaten the validity of studies investigating the relationship between neck manipulation and vertebral artery dissection stroke? No.

PubMed

Murphy, Donald R; Schneider, Michael J; Perle, Stephen M; Bise, Christopher G; Timko, Michael; Haas, Mitchell

2016-01-01

The purported relationship between cervical manipulative therapy (CMT) and stroke related to vertebral artery dissection (VAD) has been debated for several decades. A large number of publications, from case reports to case-control studies, have investigated this relationship. A recent article suggested that case misclassification in the case-control studies on this topic resulted in biased odds ratios in those studies. Given its rarity, the best epidemiologic research design for investigating the relationship between CMT and VAD is the case-control study. The addition of a case-crossover aspect further strengthens the scientific rigor of such studies by reducing bias. The most recent studies investigating the relationship between CMT and VAD indicate that the relationship is not causal. In fact, a comparable relationship between vertebral artery-related stroke and visits to a primary care physician has been observed. The statistical association between visits to chiropractors and VAD can best be explained as resulting from a patient with early manifestation of VAD (neck pain with or without headache) seeking the services of a chiropractor for relief of this pain. Sometime after the visit the patient experiences VAD-related stroke that would have occurred regardless of the care received. This explanation has been challenged by a recent article putting forth the argument that case misclassification is likely to have biased the odds ratios of the case-control studies that have investigated the association between CMT and vertebral artery related stroke. The challenge particularly focused on one of the case-control studies, which had concluded that the association between CMT and vertebral artery related stroke was not causal. It was suggested by the authors of the recent article that misclassification led to an underestimation of risk. We argue that the information presented in that article does not support the authors' claim for a variety of reasons, including the fact that the assumptions upon which their analysis is based lack substantiation and the fact that any possible misclassification would not have changed the conclusion of the study in question. Current evidence does not support the notion that misclassification threatens the validity of recent case-control studies investigating the relationship between CMT and VAD. Hence, the recent re-analysis cannot refute the conclusion from previous studies that CMT is not a cause of VAD.

Evaluation and perceived results of moral case deliberation: A mixed methods study.

PubMed

Janssens, Rien M J P A; van Zadelhoff, Ezra; van Loo, Ger; Widdershoven, Guy A M; Molewijk, Bert A C

2015-12-01

Moral case deliberation is increasingly becoming part of various Dutch healthcare organizations. Although some evaluation studies of moral case deliberation have been carried out, research into the results of moral case deliberation within aged care is scarce. How did participants evaluate moral case deliberation? What has moral case deliberation brought to them? What has moral case deliberation contributed to care practice? Should moral case deliberation be further implemented and, if so, how? Quantitative analysis of a questionnaire study among participants of moral case deliberation, both caregivers and team leaders. Qualitative analysis of written answers to open questions, interview study and focus group meetings among caregivers and team leaders. Caregivers and team leaders in a large organization for aged care in the Netherlands. A total of 61 moral case deliberation sessions, carried out on 16 care locations belonging to the organization, were evaluated and perceived results were assessed. Participants gave informed consent and anonymity was guaranteed. In the Netherlands, the law does not prescribe independent ethical review by an Institutional Review Board for this kind of research among healthcare professionals. Moral case deliberation was evaluated positively by the participants. Content and atmosphere of moral case deliberation received high scores, while organizational issues regarding the moral case deliberation sessions scored lower and merit further attention. Respondents indicated that moral case deliberation has the potential to contribute to care practice as relationships among team members improve, more openness is experienced and more understanding for different perspectives is fostered. If moral case deliberation is to be successfully implemented, top-down approaches should go hand in hand with bottom-up approaches. The relevance of moral case deliberation for care practice received wide acknowledgement from the respondents. It can contribute to the team's cohesion as mutual understanding for one another's views is fostered. If implemented well, moral case deliberation has the potential to improve care, according to the respondents. © The Author(s) 2014.

A Study of Pre-Service Information and Communication Teachers' Efficacy Levels for Analyzing and Responding to Cyberbullying Cases

ERIC Educational Resources Information Center

Kavuk, Melike; Bulu, Sanser; Keser, Hafize

2016-01-01

This case study was conducted to investigate efficacy levels of preservice Information and Communication Teachers' to identify, prevent and intervene to cyberbullying cases. Fifty participants were interviewed and 56 cyberbullying cases, which the participants experienced or witnessed, were collected to evaluate their cyberbullying readiness.…

The Woodworker's Website: A Project Management Case Study

ERIC Educational Resources Information Center

Jance, Marsha

2014-01-01

A case study that focuses on building a website for a woodworking business is discussed. Project management and linear programming techniques can be used to determine the time required to complete the website project discussed in the case. This case can be assigned to students in an undergraduate or graduate decision modeling or management science…

Exploring Small Group Analysis of Instructional Design Cases in Online Learning Environments

ERIC Educational Resources Information Center

Trespalacios, Jesus

2017-01-01

The case-based approach is a constructivist instructional strategy that helps students apply their emerging knowledge by studying design problems in authentic real-world situations. One important instructional strategy in case-based instruction is to analyze cases in small groups before discussing them with the whole class. This study investigates…

Fluent Aphasia in Telugu: A Case Comparison Study of Semantic Dementia and Stroke Aphasia

ERIC Educational Resources Information Center

Alladi, Suvarna; Mridula, Rukmini; Mekala, Shailaja; Rupela, Vani; Kaul, Subhash

2010-01-01

This study presents two cases with fluent aphasia in Telugu with semantic dementia and post-stroke fluent aphasia. Comparable scores were obtained on the conventional neuropsychological and language tests that were administered on the two cases. Both cases demonstrated fluent, grammatical and well-articulated speech with little content, impaired…

Case Studies for Management Development in Bangladesh.

ERIC Educational Resources Information Center

McLean, Gary N.

Eight case studies appropriate for use in a course in management development were prepared and are provided in this document. The typical case describes a real business situation in which a real manager had to reach a decision. The case gives quantitative and qualitative information that is, or may be, relevant to that decision. Questions for…

Making Mathematics Placement Decisions for High School Students with High Incidence Disabilities: A Collective Case Study

ERIC Educational Resources Information Center

Murzyn, Amy; Hughes, Trudie

2015-01-01

This multiple case study described the experiences of case managers making mathematics placement decisions for high school students with high incidence disabilities. Participants included three parents, three students, three case managers, three mathematics teachers, and three administrators from different high schools across rural, suburban and…

Case conceptualization research in cognitive behavior therapy: A state of the science review.

PubMed

Easden, Michael H; Kazantzis, Nikolaos

2018-03-01

Prominent models of cognitive behavior therapy (CBT) assert that case conceptualization is crucial for tailoring interventions to adequately address the needs of the individual client. We aimed to review the research on case conceptualization in CBT. We conducted a systematic search of PsychINFO, MEDLINE, Psychology and Behavioral Science Collection, and CINAHL databases to February 2016. A total of 24 studies that met inclusion criteria were identified. It was notable that studies (a) focused on the assessment function of case conceptualization, (b) employed diverse methodologies, and, overall, (c) there remains a paucity of studies examining the in-session process of using case conceptualization or examining relations with outcome. Results from the existing studies suggest that experienced therapists can reliably construct some elements of case conceptualizations, but importance for the efficacy of case conceptualization in CBT has yet to be demonstrated. Research that involves direct observation of therapist competence in case conceptualization as a predictor of CBT outcomes is recommended as a focus for future hypothesis testing. © 2017 Wiley Periodicals, Inc.

Nanomaterial Case Studies: Nanoscale Titanium Dioxide (External Review Draft)

EPA Science Inventory

This draft document presents two case studies of nanoscale titanium dioxide (nano-TiO₂) used (1) to remove arsenic from drinking water and (2) as an active ingredient in topical sunscreen. The draft case studies are organized around a comprehensive environmental asses...

Integration of Technology into the Classroom: Case Studies.

ERIC Educational Resources Information Center

Johnson, D. LaMont, Ed.; Maddux, Cleborne D., Ed.; Liu, Leping, Ed.

This book contains the following case studies on the integration of technology in education: (1) "First Steps toward a Statistically Generated Information Technology Integration Model" (D. LaMont Johnson and Leping Liu); (2) "Case Studies: Are We Rejecting Rigor or Rediscovering Richness?" (Cleborne D. Maddux); (3)…

Using Case Studies: An International Approach

ERIC Educational Resources Information Center

McClam, Tricia; Woodside, Marianne

2005-01-01

Case studies as an instructional strategy have been used in many disciplines, including law, teacher education, science, medicine, and business. Among the benefits of this method of instruction are involving students in learning, developing their critical thinking skills, promoting communication, and engaging in critical analysis. Case studies are…

Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray (Final Report)

EPA Science Inventory

EPA announced the release of the final report, Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray. This report represents a case study of engineered nanoscale silver (nano-Ag), focusing on the specific example of nano-Ag as possibly used in disinfectant spr...

Alternative Fuels Data Center: Biodiesel Fueling Stations

Science.gov Websites

Case Studies California Ramps Up Biofuels Infrastructure Green Fueling Station Powers Fleets in Upstate New York New Hampshire Railway Makes Tracks With Biodiesel More Biodiesel Case Studies | All Case Studies Publications 2016 Vehicle Technologies Market Report Biodiesel Handling and Use Guide (Fifth

Undergraduate Psychology Students' Experiences with Creative Drama: A Multi-Case Study

ERIC Educational Resources Information Center

Wilcox, Ruth A.

2015-01-01

This qualitative multi-case study explored undergraduate psychology students' experiences participating in creative drama activities the instructor/researcher developed to teach psychological concepts. The study was conducted in three introductory and developmental courses in a mid-western community college setting. Participants (cases) included…

Evaluation of the Effectiveness of the Integration of a LITEE Case Study for a Freshman Level Mechanical Engineering Course at The University of Toledo

ERIC Educational Resources Information Center

Franchetti, Matthew

2011-01-01

The purpose of this paper is to report the findings of the integration of a manufacturing case study to a freshman level mechanical engineering course at The University of Toledo. The approach to integrate this case study into the class was completed via weekly assignments analyzing the case, small group discussion, and weekly group discussion.…

The Human Drones of Isis: How 21st Century Terrorism Uses Remote Warfare

DTIC Science & Technology

2017-06-01

aftermath of 9/11 is Lorenzo Vidino’s Al Qaeda in Europe. Focusing on Al Qaeda (AQ) attacks in Europe, Vidino uses case studies of the major...the main focuses of our theory-building case study . 62 “The European Union’s Policies on Counter...it will consider case studies , and conduct cross- case comparisons in order to identify gaps in existing remote warfare theory. It will further

Cognitive neuropsychology and its vicissitudes: The fate of Caramazza's axioms.

PubMed

Shallice, Tim

2015-01-01

Cognitive neuropsychology is characterized as the discipline in which one draws conclusions about the organization of the normal cognitive systems from the behaviour of brain-damaged individuals. In a series of papers, Caramazza, later in collaboration with McCloskey, put forward four assumptions as the bridge principles for making such inferences. Four potential pitfalls, one for each axiom, are discussed with respect to the use of single-case methods. Two of the pitfalls also apply to case series and group study procedures, and the other two are held to be indirectly testable or avoidable. Moreover, four other pitfalls are held to apply to case series or group study methods. It is held that inferences from single-case procedures may profitably be supported or rejected using case series/group study methods, but also that analogous support needs to be given in the other direction for functionally based case series or group studies. It is argued that at least six types of neuropsychological method are valuable for extrapolation to theories of the normal cognitive system but that the single- or multiple-case study remains a critical part of cognitive neuropsychology's methods.

Study of placenta of children born with congenital malformations.

PubMed

Stoll, Claude; Alembik, Yves; Dott, Béatrice; Roth, Marie-Paule

2003-01-01

The malformations in this study were observed in a series of 279,642 consecutive births of known outcome registered in our Registry of congenital anomalies. For each case, more than 50 factors included in the registration forms were studied. One of the factors studied was the placenta. For each malformed child, a control was chosen. Cases with maternal known factors impairing placenta function, i.e. vasculopathy and diabetes, were excluded. In each category of malformations studied, the malformed children were divided into isolated and non-isolated (multiple malformed) cases. The weight of placenta of isolated cases was not lower than the weight of placenta of the controls. In contrast, the weight of placenta of the cases with non-isolated malformations was lower than the weight of placenta of the controls and of the isolated cases, for all categories of malformations but gastroschisis and omphalocele. The mean weights at birth of the cases with multiple malformations were also lower than those of the controls. The human placenta discounts a principal functional part, the maternal blood in the intervillous space. Congenital malformations may interact with this function.

[Relations between extraction of wisdom teeth and temporomandibular disorders: a case/control study].

PubMed

Duval, Florian; Leroux, Agathe; Bertaud, Valérie; Meary, Fleur; Le Padellec, Clément; Refuveille, Laura; Lemaire, Arnaud; Sorel, Olivier; Chauvel-Lebret, Dominique

2015-09-01

The aim of this study was to assess the impact of extraction of third molars on the occurrence of temporo-mandibular disorders (TMD). A review of the literature and a case-control study have been conducted. The case-control study compares the frequency of extraction of third molars between the sample with TMD (case) and the sample without TMD (control). The proportion of patients who had undergone extractions of wisdom teeth was higher in the case group than in the control group. The difference was statistically significant when patients had undergone extraction of all four wisdom teeth or when the extraction of four wisdom teeth underwent in one sitting or under general anesthesia. The study of patients in case sample shows that all signs of TMD were more common in patients who had undergone extractions in several sessions and under local anesthesia. The temporomandibular joint sounds are significantly more frequent with local anesthesia. In the case group, 85 to 92% of patients have parafunctions and 5 to 11% have malocclusion. This demonstrates the multifactorial etiology of temporomandibular disorders. © EDP Sciences, SFODF, 2015.

The role of professional knowledge in case-based reasoning in practical ethics.

PubMed

Pinkus, Rosa Lynn; Gloeckner, Claire; Fortunato, Angela

2015-06-01

The use of case-based reasoning in teaching professional ethics has come of age. The fields of medicine, engineering, and business all have incorporated ethics case studies into leading textbooks and journal articles, as well as undergraduate and graduate professional ethics courses. The most recent guidelines from the National Institutes of Health recognize case studies and face-to-face discussion as best practices to be included in training programs for the Responsible Conduct of Research. While there is a general consensus that case studies play a central role in the teaching of professional ethics, there is still much to be learned regarding how professionals learn ethics using case-based reasoning. Cases take many forms, and there are a variety of ways to write them and use them in teaching. This paper reports the results of a study designed to investigate one of the issues in teaching case-based ethics: the role of one's professional knowledge in learning methods of moral reasoning. Using a novel assessment instrument, we compared case studies written and analyzed by three groups of students whom we classified as: (1) Experts in a research domain in bioengineering. (2) Novices in a research domain in bioengineering. (3) The non-research group--students using an engineering domain in which they were interested but had no in-depth knowledge. This study demonstrates that a student's level of understanding of a professional knowledge domain plays a significant role in learning moral reasoning skills.

What's in a Name? The Incorrect Use of Case Series as a Study Design Label in Studies Involving Dogs and Cats.

PubMed

Sargeant, J M; O'Connor, A M; Cullen, J N; Makielski, K M; Jones-Bitton, A

2017-07-01

Study design labels are used to identify relevant literature to address specific clinical and research questions and to aid in evaluating the evidentiary value of research. Evidence from the human healthcare literature indicates that the label "case series" may be used inconsistently and inappropriately. Our primary objective was to determine the proportion of studies in the canine and feline veterinary literature labeled as case series that actually corresponded to descriptive cohort studies, population-based cohort studies, or other study designs. Our secondary objective was to identify the proportion of case series in which potentially inappropriate inferential statements were made. Descriptive evaluation of published literature. One-hundred published studies (from 19 journals) labeled as case series. Studies were identified by a structured literature search, with random selection of 100 studies from the relevant citations. Two reviewers independently characterized each study, with disagreements resolved by consensus. Of the 100 studies, 16 were case series. The remaining studies were descriptive cohort studies (35), population-based cohort studies (36), or other observational or experimental study designs (13). Almost half (48.8%) of the case series or descriptive cohort studies, with no control group and no formal statistical analysis, included inferential statements about the efficacy of treatment or statistical significance of potential risk factors. Authors, peer-reviewers, and editors should carefully consider the design elements of a study to accurately identify and label the study design. Doing so will facilitate an understanding of the evidentiary value of the results. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

The effect of compliance on contact lens case contamination.

PubMed

Tilia, Daniel; Lazon de la Jara, Percy; Zhu, Hua; Naduvilath, Thomas J; Holden, Brien A

2014-03-01

To determine the efficacy of written instructions on contact lens case hygiene and to quantify the effect of noncompliance on contact lens case contamination. Data were retrospectively analyzed from 16 prospective, 3-month daily-wear studies during which six commercially available silicone hydrogel contact lenses and seven lens care solutions (LCS) were tested following a similar protocol. Verbal instructions regarding case hygiene (rinse case with LCS, not tap water) were given in nine studies, while the same instructions were given verbally and in written format in seven studies. A survey on contact lens, LCS, and lens case hygiene was completed at 1- and 3-month visits and compliance with case hygiene instructions was determined. Regular contact lens cases were used for 1 month and collected for microbial analysis at the 1- and 3-month visits. The rate of case contamination and the types of microbes contaminating cases were evaluated. Participants given verbal and written instructions were more likely to be compliant with case hygiene instructions than those just given verbal instructions (odds ratio [OR]: 2.19, p < 0.001, 95% confidence interval [CI]: 1.40-3.44). The overall case contamination rate was 79%. Use of tap water to rinse contact lens cases was associated with significantly more cases contaminated with Gram-negative bacteria (GNB) (30% vs. 10%, p < 0.001), a greater risk of GNB case contamination (OR: 2.91, p < 0.001. 95% CI: 1.72-4.92), and a higher quantity of GNB in cases (mean colony-forming unit/case ± SD: 28,286 ± 131,935 vs. 6477 ± 60,447, p < 0.001). Lens case hygiene can be improved by effective communication of instructions. Contact lens wearers should be actively discouraged from rinsing contact lens cases with tap water because of the increased risk of GNB contamination.

Roles and Educational Effects of Clinical Case Studies in Home Medical Care.

PubMed

Ohsawa, Tomoji; Shimazoe, Takao

2017-01-01

Due to the progression of aging in Japan, pharmacists need to participate in home medical care. To enable pharmacists with no previous experience to participate in home medical care of patients with various diseases in the home environment, it is necessary to adopt an approach of training them in advance. It is thought useful for such clinical training to include patient case studies, which may facilitate the training of pharmacists for home medical care through simulated experience. "The working group to create home clinical cases for education" was launched by a group of university faculty, who have educational knowledge, and trained pharmacists who work with the patients at home. The home care cases were compiled by the university faculty members and the home care practice pharmacists. Working pharmacists and students at pharmaceutical college studied the same case studies of home medical care, and their self-evaluations were compared. They showed that the students rated themselves higher than the pharmacists. One of the reasons was the systematic education of the case studies. The clinical case studies are a good educational tool to promote home care medicine in pharmacies and university pharmaceutical colleges.

The risk of acute liver injury among users of antibiotic medications: a comparison of case-only studies.

PubMed

Brauer, Ruth; Ruigómez, Ana; Klungel, Olaf; Reynolds, Robert; Feudjo Tepie, Maurille; Smeeth, Liam; Douglas, Ian

2016-03-01

The aims of this study were two-fold: (i) to investigate the effect of exposure to antibiotic agents on the risk of acute liver injury using a self-controlled case series and case-crossover study and (ii) to compare the results between the case-only studies. For the self-controlled case series study relative incidence ratios (IRR) were calculated by dividing the rate of acute liver injury experienced during patients' periods of exposure to antibiotics to patients' rate of events during non-exposed time using conditional Poisson regression. For the case-crossover analysis we calculated Odds Ratios (OR) using conditional logistic regression by comparing exposure during 14- and 30-day risk windows with exposure during control moments. Using the self-controlled case series approach, the IRR was highest during the first 7 days after receipt of a prescription (10.01, 95% CI 6.59-15.18). Omitting post-exposure washout periods lowered the IRR to 7.2. The highest estimate in the case-crossover analysis was found when two 30-day control periods 1 year prior to the 30-day ALI risk period were retained in the analysis: OR = 6.5 (95% CI, 3.95-10.71). The lowest estimate was found when exposure in the 14-day risk period was compared to exposure in four consecutive 14-day control periods immediately prior to the risk period (OR = 3.05, 95% CI, 2.06-4.53). An increased relative risk of acute liver injury was consistently observed using both self-controlled case series and case-crossover designs. Case-only designs can be used as a viable alternative study design to study the risk of acute liver injury, albeit with some limitations. © 2015 The Authors Pharmacoepidemiology and Drug Safety Published by John Wiley & Sons Ltd.

Pre-Service Teachers' Defensive Pessimism in Situ: Two Case Studies within a Mathematics Classroom

ERIC Educational Resources Information Center

Merz, Alice H.; Swim, Terri Jo

2008-01-01

In this study, defensive pessimism is reviewed in relation to anxiety, self-esteem, expectations, self-regulation, and self-handicapping. Then, two case studies of American pre-service teachers in a mathematics classroom are provided that move the research beyond survey and correlational studies. In the case analyses, defensive pessimists'…

Using Case Studies in Business Education to Promote Networked Thinking: Findings of an Intervention Study

ERIC Educational Resources Information Center

Pilz, Matthias; Zenner, Lea

2018-01-01

Case studies are central to the way management is currently taught at universities. Among other benefits attributed to the case study method is that it promotes networked thinking by learners. Networked thinking takes account of interactions and repercussions, making it crucial to decision-making within the complex system of rules that shapes…

22 CFR 96.53 - Background studies on the child and consents in outgoing cases.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Background studies on the child and consents in... United States (outgoing Cases) § 96.53 Background studies on the child and consents in outgoing cases. (a) The agency or person takes all appropriate measures to ensure that a child background study is...

22 CFR 96.53 - Background studies on the child and consents in outgoing cases.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Background studies on the child and consents in... United States (outgoing Cases) § 96.53 Background studies on the child and consents in outgoing cases. (a) The agency or person takes all appropriate measures to ensure that a child background study is...

22 CFR 96.53 - Background studies on the child and consents in outgoing cases.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Background studies on the child and consents in... United States (outgoing Cases) § 96.53 Background studies on the child and consents in outgoing cases. (a) The agency or person takes all appropriate measures to ensure that a child background study is...

22 CFR 96.53 - Background studies on the child and consents in outgoing cases.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Background studies on the child and consents in... United States (outgoing Cases) § 96.53 Background studies on the child and consents in outgoing cases. (a) The agency or person takes all appropriate measures to ensure that a child background study is...

22 CFR 96.53 - Background studies on the child and consents in outgoing cases.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Background studies on the child and consents in... United States (outgoing Cases) § 96.53 Background studies on the child and consents in outgoing cases. (a) The agency or person takes all appropriate measures to ensure that a child background study is...

Overview of EPA's Approach to Developing Prospective Case Studies Technical Workshop: Case Studies to Assess Potential Impacts of Hydraulic Fracturing on Drinking Water Resources

EPA Science Inventory

One component of the United States Environmental Protection Agency's (EPA) study of the potential impacts of hydraulic fracturing on drinking water resources is prospective case studies, which are being conducted to more fully understand and assess if and how site specific hydrau...

Hot under the Collar: Weighing the Dangers of a Weight-Loss Drug

ERIC Educational Resources Information Center

DeSimone, Susan M.; Genereux, Annie Prud'homme

2011-01-01

This column provides original articles on innovations in case study teaching, assessment of the method, as well as case studies with teaching notes. In this month's issue the goal of the case study is for students to expand their understanding of membrane permeability and the proton motive force in mitochondria through the study of…

Alternative Fuels Data Center: E15

Science.gov Websites

Data | All Maps & Data Case Studies Idaho County Employs FFVs and Idle Reduction More Ethanol Case Studies | All Case Studies Publications Handbook for Handling, Storing, and Dispensing E85 and Other Ethanol-Gasoline Blends E15 and Infrastructure Review and Evaluation of Studies on the Use of E15 in Light

Methodological Considerations for an Evolving Model of Institutional Research.

ERIC Educational Resources Information Center

Jones, Timothy B.; Essien-Barrett, Barbara; Gill, Peggy B.

A multi-case study was used in the self-study of three programs within an academic department of a mid-sized Southern university. Multi-case methodology as a form of self-study encourages a process of self-renewal and programmatic change as it defines an active stakeholder role. The participants in the three case studies were university faculty…

Case Studies of Multilingual/Multicultural Asian Deaf Adults: Strategies for Success

ERIC Educational Resources Information Center

Wang, Qiuying; Andrews, Jean; Liu, Hsiu Tan; Liu, Chun Jung

2016-01-01

Case studies of adult d/Deaf or Hard of Hearing Multilingual Learners (DMLs) are few, especially studies of DMLs who learn more than one sign language and read logographic and alphabetic scripts. To reduce this paucity, two descriptive case studies are presented. Written questionnaires, face-to-face interviews, and self-appraisals of language-use…

Case Study: The Hunger Pains--Ghrelin, Weight Loss, and Maintenance

ERIC Educational Resources Information Center

Diener, Lynn M.

2013-01-01

This article presents a case study regarding healthy weight loss and the role of the hormone ghrelin in maintaining a lower body weight. This study was designed specifically for use in an introductory college-level physiology course. It addresses the use of the case study in teaching digestion and metabolism, exploring the role of hormones in…

Moving beyond Mentoring: A Collective Case Study Examining the Perceived Characteristics of Positive Transformational Figures

ERIC Educational Resources Information Center

Bean, Brent W.; Kroth, Michael

2013-01-01

The purpose of this collective-case study was to explore the characteristics of transformational figures. This study revealed that interpersonal encounters were seen as a catalyst that assisted study participants through the process of transformation. Ten themes emerged from the cross-case analysis: Imposed and Intentional Influence; Metaphors of…

Improving Assistive Technology Service by Using 3D Printing: Three Case Studies.

PubMed

Watanabe, Takashi; Hatakeyama, Takuro; Tomiita, Mitsuru

2015-01-01

Assistive technology services are essential for adapting assistive devices to the individual needs of users with disabilities. In this study, we attempted to apply three-dimensional (3D) printing technology to three actual cases, and to study its use, effectiveness, and future applications. We assessed the usefulness of 3D printing technology by categorizing its utilization after reviewing the outcomes of these case studies. In future work, we aim to gather additional case studies and derive information on using 3D printing technology that will enable its effective application in the process of assistive technology services.

Reflection of a therapeutic touch experience: case study 2.

PubMed

Green, C A

1998-02-01

The purpose of this case study was to explore the experience of both giving and receiving Therapeutic Touch. A subjective account of the Therapeutic Touch experience is given in an attempt to throw light on its unique creative and therapeutic qualities. In most instances it was shown that the experience of both giving and receiving Therapeutic Touch was a parallel experience. This case study explores the effects of Therapeutic Touch on a client experiencing pain and associated anxiety. Whilst a response to treatment was observed, the need for further case studies and research studies in this area was identified.

A Systematic Review Comparing the Acceptability, Validity and Concordance of Discrete Choice Experiments and Best-Worst Scaling for Eliciting Preferences in Healthcare.

PubMed

Whitty, Jennifer A; Oliveira Gonçalves, Ana Sofia

2018-06-01

The aim of this study was to compare the acceptability, validity and concordance of discrete choice experiment (DCE) and best-worst scaling (BWS) stated preference approaches in health. A systematic search of EMBASE, Medline, AMED, PubMed, CINAHL, Cochrane Library and EconLit databases was undertaken in October to December 2016 without date restriction. Studies were included if they were published in English, presented empirical data related to the administration or findings of traditional format DCE and object-, profile- or multiprofile-case BWS, and were related to health. Study quality was assessed using the PREFS checklist. Fourteen articles describing 12 studies were included, comparing DCE with profile-case BWS (9 studies), DCE and multiprofile-case BWS (1 study), and profile- and multiprofile-case BWS (2 studies). Although limited and inconsistent, the balance of evidence suggests that preferences derived from DCE and profile-case BWS may not be concordant, regardless of the decision context. Preferences estimated from DCE and multiprofile-case BWS may be concordant (single study). Profile- and multiprofile-case BWS appear more statistically efficient than DCE, but no evidence is available to suggest they have a greater response efficiency. Little evidence suggests superior validity for one format over another. Participant acceptability may favour DCE, which had a lower self-reported task difficulty and was preferred over profile-case BWS in a priority setting but not necessarily in other decision contexts. DCE and profile-case BWS may be of equal validity but give different preference estimates regardless of the health context; thus, they may be measuring different constructs. Therefore, choice between methods is likely to be based on normative considerations related to coherence with theoretical frameworks and on pragmatic considerations related to ease of data collection.

Physiologic study of the terminal digestive tract in chronic painful constipation.

PubMed Central

Meunier, P

1986-01-01

A manometric study of the sigmoid colon and of the anorectum was undertaken in 65 chronically constipated patients complaining of abdominal pain, and in a control group of 23 healthy volunteers. Rectal compliance was tested in both groups. The sigmoid motility study allowed for the segregation of the constipated patients into three groups: hypokinesia (12 cases), normokinesia (34 cases), hyperkinesia (19 cases). Rectal manometry showed anal hypertony in 24 patients, impaired rectal conscious sensitivity in 12 subjects, and normal functions in the remaining cases. The rectal compliance study disclosed a decreased compliance in 15 cases and increased compliance in 13 other patients. In 12 cases disordered sigmoid motility was the only abnormality; in 10 cases only a rectoanal abnormality was found. Most of the patients (52%) exhibited miscellaneous disorders. In contrast, all parameters were normal in nine subjects. No consistent pattern of motility disorders was thus demonstrated in this clinically homogeneous group of patients with chronic, painful, constipation. PMID:3758814

Visual memory effects on intraoperator study design: determining a minimum time gap between case reviews to reduce recall bias.

PubMed

Campbell, W Scott; Talmon, Geoffrey A; Foster, Kirk W; Baker, John J; Smith, Lynette M; Hinrichs, Steven H

2015-03-01

The objective of this research was to determine test intervals between intraoperator case reviews to minimize the impact of recall. Three pathologists were presented with a group of 120 slides and subsequently challenged with a study set of 120 slides after 2-week and 4-week intervals. The challenge set consisted of 60 slides seen during the initial review and 60 slides previously unseen within the study. Pathologists rendered a diagnosis for each slide and indicated whether they recalled seeing the slide previously (yes/no). Two weeks after having been shown 60 cases from a challenge set of 120 cases, the pathologists correctly remembered 26, 22, and 24 cases or 40% overall. After 4 weeks, the pathologists correctly recalled 31% of cases previously seen. Pathologists were capable of recalling from memory cases seen previously at 2 and 4 weeks. Recall rates may be sufficiently high to affect intraobserver study design. Copyright© by the American Society for Clinical Pathology.

[Mucus secreting tumors of the appendix. Report of 22 cases].

PubMed

Beyrouti, Mohamed Issam; Gharbi, Ahmed; Abid, Mohamed; Beyrouti, Ramez; Kharrat, Madiha; Gargouri, Faouzi; Gharbi, Walid; Tafech, Issam; Affes, Najmeddine; Khebir, Abdelmajid; Sellami, Abdelhafidh

2004-12-01

The retrospective study presented in this article was realized on a series of 22 cases of mucus secreting tumor of the appendix compiled among 8373 appendicectomies. The clinical picture was dominated by an appendiceal syndrome (73%). The diagnosis was made pre or peroperatively in 10 cases and it was only with to the systematic anatomopathologic exam that 12 other cases were discovered. The histological study of the appendectomy piece showed a retention mucocele (12 cases), a mucosal hyperplasia (8 cases) and a cystadenoma (2 cases). For 5 patients, the diagnosis of peritoneal pseudomyxoma (4 cases) or extraperitoneal (1 case) was retained. All the patients underwent an appendicectomy, associated to an evacuation of the peritoneal gelatinous ascites for 5 patients among whom two underwent in more an omentectomie. Two cases of recurrence were recorded 5 months later.

The West. Grade Five (Unit V). Resource Unit. Project Social Studies.

ERIC Educational Resources Information Center

Minnesota Univ., Minneapolis. Project Social Studies Curriculum Center.

This resource unit for 5th graders includes three case studies and a sub-unit on the West as a region. Three sequent occupance case studies which are suggestive, rather than prescriptive, comprise the first part of the unit. Teachers may decide to select only one for an in-depth study or may decide to design a case study modeled after this…

[Cutaneous tuberculosis in Bamako, Mali].

PubMed

Dicko, Adama; Faye, Ousmane; Fofana, Youssouf; Soumoutera, Moussa; Berthé, Siritio; Touré, Saidou; Traoré, Bekaye; Guindo, Binta; Tall, Koureissi; Keita, Alimata; Kéita, Lassine; Coulibaly, Karim; Keita, Somita

2017-01-01

Tuberculosis is the most common mycobacteriosis in sub-Saharan Africa. Cutaneous tuberculosis is rare and underdiagnosed due to its clinical polymorphism and to the smallness of technical equipment. This study aims to describe the epidemiological, clinical, histopathological aspects of cutaneous tuberculosis in Bamako (Mali). We conducted a cross-sectional descriptive study from January 1991 to December 2008. The study was performed in the Department of Dermatology at the National Center for Disease Control and in the Department of Pneumophtisiology at the Hospital of Point G. The patients with tuberculosis confirmed by histological and/or biological examination were included in the study. Out of 4269 patients? medical records, 61 cases of cutaneous tuberculosis were identified (1.43%). Men accounted for 59% of the cases (36 patients) and women 41% (25 cases); sex-ratio was 1.44. The age of the patients ranged from 3 months to 61 years, with an average age of 27.56 ± 36 years. The average length of follow-up was 10.9 ± 10 months. The identified clinical forms were scrofuloderma (41 cases), ulcerative form (13 cases), verrucous form (4 cases), and tuberculous Lupus (3 cases). Tuberculosis was associated with HIV in 7 cases, with leprosy in 3 cases. Cutaneous tuberculosis is underdiagnosed in Mali. Efforts are needed to improve the accessibility and the technical equipment available in the Departments, in order to conduct an extensive interdisciplinary study on this pathology.

Effectiveness of reactive oral cholera vaccination in rural Haiti: a case-control study and bias-indicator analysis.

PubMed

Ivers, Louise C; Hilaire, Isabelle J; Teng, Jessica E; Almazor, Charles P; Jerome, J Gregory; Ternier, Ralph; Boncy, Jacques; Buteau, Josiane; Murray, Megan B; Harris, Jason B; Franke, Molly F

2015-03-01

Between April and June, 2012, a reactive cholera vaccination campaign was done in Haiti with an oral inactivated bivalent whole-cell vaccine. We aimed to assess the effectiveness of the vaccine in a case-control study and to assess the likelihood of bias in that study in a bias-indicator study. Residents of Bocozel or Grand Saline who were eligible for the vaccination campaign (ie, age ≥12 months, not pregnant, and living in the region at the time of the vaccine campaign) were included. In the primary case-control study, cases had acute watery diarrhoea, sought treatment at one of three participating cholera treatment units, and had a stool sample positive for cholera by culture. For each case, four control individuals who did not seek treatment for acute watery diarrhoea were matched by location of residence, enrolment time (within 2 weeks of the case), and age (1-4 years, 5-15 years, and >15 years). Cases in the bias-indicator study were individuals with acute watery diarrhoea with a negative stool sample for cholera. Controls were selected in the same manner as in the primary case-control study. Trained staff used standard laboratory procedures to do rapid tests and stool cultures from study cases. Participants were interviewed to collect data on sociodemographic characteristics, risk factors for cholera, and self-reported vaccination. Data were analysed by conditional logistic regression, adjusting for matching factors. From Oct 24, 2012, to March 9, 2014, 114 eligible individuals presented with acute watery diarrhoea and were enrolled, 25 of whom were subsequently excluded. 47 participants were analysed as cases in the vaccine effectiveness case-control study and 42 as cases in the bias-indicator study. 33 (70%) of 47 cholera cases self-reported vaccination versus 167 (89%) of 188 controls (vaccine effectiveness 63%, 95% CI 8-85). 27 (57%) of 47 cases had certified vaccination versus 147 (78%) of 188 controls (vaccine effectiveness 58%, 13-80). Neither self-reported nor verified vaccination was significantly associated with non-cholera diarrhoea (vaccine effectiveness 18%, 95% CI -208 to 78 by self-report and -21%, -238 to 57 by verified vaccination). Bivalent whole-cell oral cholera vaccine effectively protected against cholera in Haiti from 4 months to 24 months after vaccination. Vaccination is an important component of efforts to control cholera epidemics. National Institutes of Health, Delivering Oral Vaccines Effectively project, and Department of Global Health and Social Medicine at Harvard Medical School. Copyright © 2015 Ivers et al. Open Access article distributed under the terms of CC BY-NC-ND. Published by .. All rights reserved.

An Approach for Integrating Toxicogenomic Data in Risk Assessment: The Dibutyl Phthalate Case Study

EPA Science Inventory

An approach for evaluating and integrating genomic data in chemical risk assessment was developed based on the lessons learned from performing a case study for the chemical dibutyl phthalate. A case study prototype approach was first developed in accordance with EPA guidance and ...

Library-ABE Projects. Case Studies.

ERIC Educational Resources Information Center

MacVicar, Phyllis

This document contains 41 case studies submitted to the Appalachian Adult Education Center by the staffs of four projects demonstrating library services to disadvantaged adults, in cooperation with adult basic education programs. Included in each case study is the coping skill area in which an individual need was recognized and met through the…

Case Study: Formulating Questions That Address Student Misconceptions in a Case Study

ERIC Educational Resources Information Center

Prud'homme-Généreux, Annie

2017-01-01

Misconceptions are sometimes called "alternative conceptions" in acknowledgement of the fact that although these concepts are inaccurate, they are congruent with prior experiences. The idea that misconceptions must be addressed to improve learning is helpful to remember when developing a case study. Students will bring their existing…

LESSONS FROM THE FRONT: A CASE STUDY OF RUSSIAN CYBER WARFARE

DTIC Science & Technology

2015-12-01

Lessons From The Front: A Case Study Of Russian Cyber Warfare looks to capitalize on the lessons learned from the alleged Russian cyber-offensive on...through the careful analysis and comparison of two disparate conflicts related by their collision with Russian cyber - warfare . Following case study

An Exploration of Mathematics Graduate Teaching Assistants' Teaching Philosophies: A Case Study

ERIC Educational Resources Information Center

Nepal, Kedar Mani

2014-01-01

This multi-case study is an exploration of mathematics graduate teaching assistants' teaching philosophies. It focused on the cases of four purposefully selected beginning mathematics graduate teaching assistants (MGTAs) including two domestic and two international MGTAs. Using qualitative research methods, this dissertation study focused on the…

Corporate Energy Conservation Program for Alcoa North American Extrusions: Office of Industrial Technologies (OIT) Aluminum BestPractices Management Case Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

U.S. Department of Energy

2001-08-06

This case study is the latest in a series on industrial firms who are implementing energy efficient technologies and system improvements into their manufacturing processes. The case studies document the activities, savings, and lessons learned on these projects.

Work Sharing Case Studies.

ERIC Educational Resources Information Center

McCarthy, Maureen E.; And Others

Designed to provide private sector employers with the practical information necessary to select and then to design and implement work sharing arrangements, this book presents case studies of some 36 work sharing programs. Topics covered in the case studies include the circumstances leading to adoption of the program, details of compensation and…

A case study : Georgia's intelligent transportation system : NAVIGATOR systems integrator contract -- use of a systems integrator to manage ITS implementation

DOT National Transportation Integrated Search

2000-03-01

This case study is one of a series of case studies that examine procurement approaches used to deliver Intelligent Transportation System (ITS) projects. ITS projects are often complex and leverage the latest technology in telecommunications, computer...

Using Clinical Gait Case Studies to Enhance Learning in Biomechanics

ERIC Educational Resources Information Center

Chester, Victoria

2011-01-01

Clinical case studies facilitate the development of clinical reasoning strategies through knowledge and integration of the basic sciences. Case studies have been shown to be more effective in developing problem-solving abilities than the traditional lecture format. To enhance the learning experiences of students in biomechanics, clinical case…

Chemical Case Studies: Science-Society "Bonding."

ERIC Educational Resources Information Center

Hofstein, Avi; Nae, Nehemia

1981-01-01

Describes a unit designed to illustrate the "science-society-technology connection," in which three case studies of the chemical industry in Israel are presented to high school chemistry students. Chosen for the unit are case studies on copper production in Timna, on plastics, and on life from the Dead Sea. (CS)

Brand Caliphate And Recruitment Between The Genders

DTIC Science & Technology

2016-09-01

females. However, six case studies of radicalized females suggests the recruitment of these women does not appear to be directly attributable to the...propaganda, it appears IS tried to deliver messaging targeted toward females. However, six case studies of radicalized females suggests the...23 B. TEXTUAL ANALYSIS ...........................................................................23 C. CASE STUDIES

Case-Based Independent Study for Medical Students in Emergency Psychiatry

ERIC Educational Resources Information Center

Hirshbein, Laura D.; Gay, Tamara

2005-01-01

OBJECTIVE: Brief cases designed for independent study were developed to allow third-year medical students some exposure to important concepts in emergency psychiatry during their required psychiatry clerkship. METHODS: Five independent study cases were given to University of Michigan third-year medical students during their psychiatry clerkship,…

Case Studies for Educational Leadership: Solving Administrative Dilemmas

ERIC Educational Resources Information Center

Midlock, Stephen F.

2010-01-01

"Case Studies for Educational Leadership" gives educational leadership students an opportunity to project themselves into real-life administrative situations and prepare for their future positions in the field. Each case study contained in this practical first edition book asks students to analyze complex problems, consider the moral ramifications…

75 FR 65355 - Agency Forms Undergoing Paperwork Reduction Act Review

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-22

... Project Case Studies of Communities and States Funded under Community Activities under the Communities..., system, and environmental changes. Intensive case studies will be conducted with 24 sites: Six ARRA... Act. The case study sites will be selected to include a mix of State or community characteristics...

Bridging the Performance Gap with Ergonomics: A Case Study

ERIC Educational Resources Information Center

Rethaber, James D.

2011-01-01

Faced with increased incidences of work-related strain and sprain injuries and OSHA-recordable injuries, the organization in this case study details how it resolved these performance-related issues. This case study also demonstrates the effectiveness of Thomas Gilbert's (1978) Behavior Engineering Model as a tool for analyzing, defining, and…

Alternative Fuels Data Center: Propane Fueling Stations

Science.gov Websites

Fueling Station Locations by State More Propane Data | All Maps & Data Case Studies Michigan School Prisons Adopt Propane, Establish Fuel Savings for Years to Come More Propane Case Studies | All Case Studies Publications The Growing Presence of Propane in Pupil Transportation Costs Associated With Propane

Alternative Fuels Data Center: Biodiesel Fueling Infrastructure Development

Science.gov Websites

Biodiesel Fueling Station Locations by State More Biodiesel Data | All Maps & Data Case Studies Recycled Fuels Help Ensure America's National Parks Stay Green for Another Century More Biodiesel Case Studies | All Case Studies Publications 2016 Vehicle Technologies Market Report Biodiesel Handling and Use Guide

A Case Study of "Empathetic Teaching Artistry"

ERIC Educational Resources Information Center

Risner, Doug

2014-01-01

This case study is one of twenty cases derived from Anderson and Risner's international study of teaching artists in dance, and theatre, which investigated participants' (n=172) artistic and academic preparation in dance, and theatre, initial entry into the teaching artist field, rewards, challenges, and obstacles in participants' work, artists'…

A Constructive Controversy Approach to "Case Studies"

ERIC Educational Resources Information Center

Bird, Sharon R.; Erickson, Karla A.

2010-01-01

On the basis of analysis of student responses to a case study titled "Drinks and Dinner," the authors evaluate the pedagogical potential of using constructive controversy case studies to teach about inequality. "Drinks and Dinner" is designed to capture the complexity of social interactions that defy simple solutions to engage students in…

The Campaign: A Case Study in Identity Construction through Performance

ERIC Educational Resources Information Center

Riddle, Matthew D.

2009-01-01

This article undertakes a detailed case study of "The Campaign", a teaching and learning innovation in media and communications that uses an online educational role-play. The case study draws on the qualitative analysis of classroom observations, online communications and semi-structured interviews, employing an interpretive approach…

Center for the Built Environment: Research on Controls and Information

Science.gov Websites

Foundation Complex Case Study Publications Research Area : Sustainability, Whole Building Energy, and Other commercial building energy use. Krege Foundation Complex Case Study Analyzing performance of LEED platinum criteria for high performance buildings. Building test equipment The first in-depth case study was

Best practices in intercultural health: five case studies in Latin America

PubMed Central

Mignone, Javier; Bartlett, Judith; O'Neil, John; Orchard, Treena

2007-01-01

The practice of integrating western and traditional indigenous medicine is fast becoming an accepted and more widely used approach in health care systems throughout the world. However, debates about intercultural health approaches have raised significant concerns. This paper reports findings of five case studies on intercultural health in Chile, Colombia, Ecuador, Guatemala, and Suriname. It presents summary information on each case study, comparatively analyzes the initiatives following four main analytical themes, and examines the case studies against a series of the best practice criteria. PMID:17803820

A Case Study of Land Treatment in a Cold Climate-West Dover, Vermont,

DTIC Science & Technology

1982-12-01

Research & ADA124~i8Engineering Laboratory A case study of land treatment in a cold climate- West Dover, Vermont IT C;0 ~󈨜 03 09 052 CRREL Report 82...44 December 1982 A case study of land treatment in a cold climate- West Dover, Vermont J.R. Bouzoun, D.W. Meals and E.A. Cassell Prepared for OFFICE OF...4. TITLE (end SL : 5. TYPE OF REPORT & PERIOD COVERED A CASE STUDY OF LAND TREATMENT IN A COLD CLIMATE-WEST DOVER, VERMONT 6. PERFORMING ORG. REPORT

Resilience in Utility Technologies

NASA Astrophysics Data System (ADS)

Seaton, Roger

The following sections are included: * Scope of paper * Preamble * Background to the case-study projects * Source projects * Resilience * Case study 1: Electricity generation * Context * Model * Case study 2: Water recycling * Context * Model * Case study 3: Ecotechnology and water treatment * Context * The problem of classification: Finding a classificatory solution * Application of the new taxonomy to water treatment * Concluding comments and questions * Conclusions * Questions and issues * Purposive or Purposeful? * Resilience: Flexibility and adaptivity? * Resilience: With respect of what? * Risk, uncertainty, surprise, emergence - What sort of shock, and who says so? * Co-evolutionary friction * References

Teachers' and Researchers' Beliefs of Learning and the use of Learning Progressions

NASA Astrophysics Data System (ADS)

Clapp, Francis Neely

In the last decade, science education reform in the United States has emphasized the exploration of cognitive learning pathways, which are theories on how a person learns a particular science subject matter. These theories are based, in part, by Piagetian developmental theory. One such model, called Learning Progressions (LP), has become prominent within science education reform. Science education researchers design LPs which in turn are used by science educators to sequence their curricula. The new national science standards released in April 2013 (Next Generation Science Standards) are, in part, grounded in the LP model. Understanding how teachers apply and use LPs, therefore, is valuable because professional development programs are likely to use this model, given the federal attention LP have received in science education reform. I sought to identify the beliefs and discourse that both LP developers and intended LP implementers have around student learning, teaching, and learning progressions. However, studies measuring beliefs or perspectives of LP-focused projects are absent in published works. A qualitative research is therefore warranted to explore this rather uncharted research area. Research questions were examined through the use of an instrumental case study. A case study approach was selected over other methodologies, as the research problem is, in part, bound within a clearly identifiable case (a professional development experience centering on a single LP model). One of the broadest definitions of a case study is noted by Becker (1968), who stated that goals of case studies are "to arrive at a comprehensive understanding of the groups under study" and to develop "general theoretical statements about regularities in social structure and process." (p.233). Based on Merriam (1985) the general consensus in the case study literature is that the assumptions underlying this method are common to naturalistic inquiry with research conducted primarily in the field with little control of variables. Beyond this similarity, different researchers have varying definitions to case studies. Merriam's (1985) provided a summary of the delineations and varying types of case studies. Merriam divided the various case study methods by their functions, with a marked divide between theory building and non-theory building methods. Non-theory building case studies are generally descriptive, and interpretive methods that apply theory to a case or context allow researchers to better understand the phenomena observed (Lijphart, 1971; Merriam, 1985). Conversely, theory building case studies focus on hypothesis generation, theory confirming, theory informing, or theory refuting (Lijphart, 1971; Merriam, 1985). Though there are many definitions and methods labeled as 'case studies,' for the purpose of this study, Yin's (1981) definition of a case study will be used. Yin (1981) defined a case study as a method to examine "(a) a contemporary phenomenon in its real-life context, especially when (b) the boundaries between phenomenon and context are not clearly evident" (p. 59). My study seeks to apply theory and study phenomena in their context, as I will examine teachers' practice in context of their respective classrooms. This study focuses on the lived experiences of both teacher and research stakeholders within the study. Specifically, I interviewed teachers who participated in a year-long teacher-in-residence (TiR) program. In addition, researchers/content experts who conceptualized the LP were also interviewed. Because the TiR experience was a form of professional development, I propose to study the impact that it had on participants' perceptions of the LP and any teacher-reported changes in their respective classrooms. However, because beliefs influence the language that we use to describe phenomena (such as learning and teaching), it is informative to also describe patterns in how LP developers explain learning and teaching. Subsequently, the results of this study will inform literature on both science teacher professional development and LPs theory to practice.

Spatiotemporal analysis of indigenous and imported dengue fever cases in Guangdong province, China.

PubMed

Li, Zhongjie; Yin, Wenwu; Clements, Archie; Williams, Gail; Lai, Shengjie; Zhou, Hang; Zhao, Dan; Guo, Yansha; Zhang, Yonghui; Wang, Jinfeng; Hu, Wenbiao; Yang, Weizhong

2012-06-12

Dengue fever has been a major public health concern in China since it re-emerged in Guangdong province in 1978. This study aimed to explore spatiotemporal characteristics of dengue fever cases for both indigenous and imported cases during recent years in Guangdong province, so as to identify high-risk areas of the province and thereby help plan resource allocation for dengue interventions. Notifiable cases of dengue fever were collected from all 123 counties of Guangdong province from 2005 to 2010. Descriptive temporal and spatial analysis were conducted, including plotting of seasonal distribution of cases, and creating choropleth maps of cumulative incidence by county. The space-time scan statistic was used to determine space-time clusters of dengue fever cases at the county level, and a geographical information system was used to visualize the location of the clusters. Analysis were stratified by imported and indigenous origin. 1658 dengue fever cases were recorded in Guangdong province during the study period, including 94 imported cases and 1564 indigenous cases. Both imported and indigenous cases occurred more frequently in autumn. The areas affected by the indigenous and imported cases presented a geographically expanding trend over the study period. The results showed that the most likely cluster of imported cases (relative risk = 7.52, p < 0.001) and indigenous cases (relative risk = 153.56, p < 0.001) occurred in the Pearl River Delta Area; while a secondary cluster of indigenous cases occurred in one district of the Chao Shan Area (relative risk = 471.25, p < 0.001). This study demonstrated that the geographic range of imported and indigenous dengue fever cases has expanded over recent years, and cases were significantly clustered in two heavily urbanised areas of Guangdong province. This provides the foundation for further investigation of risk factors and interventions in these high-risk areas.