bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterizing Jointed Systems by Azimuthal Resistivity Surveys
Authors: Taylor Robert W. , Fleming Anthony H. 
Published: March 2006

ABSTRACTAnisotropy, directional connectivity, and porosity of fracture systems can be estimated from surface azimuthal electrical resistivity surveys. Azimuthal resistivity surveys utilize conventional resistivity equipment and are performed by rotating a Wenner array about a fixed center point and measuring apparent resistivity as a function of azimuth. The depth of investigation is determined by the electrode spacing which is generally limited by practical considerations to approximately 70 m. The azimuthal survey generates an apparent resistivity ellipse from which the properties of a subsurface joint system can be determined. Theoretically the major axis of the resistivity ellipse will coincide with strike of the primary joint set. The ratio of major axis to minor axis of the ellipse defines the coefficient of anisotropy associated with the joints, and from this coefficient, secondary porosity can be calculated.Application of azimuthal surveys at 60 sites in bedrock and clayey till throughout Wisconsin generally yielded joint strikes within a few degrees of direct observations. Porosities calculated for jointed bedrock are within a few percent of values determined by other methods. The absolute values of porosities calculated for the tills appear unreliable due to conduction effects along the surface of clay minerals.Although the theoretical foundation for this technique is based on idealized jointing, the field results indicate that the method is effective in media with multiple joint sets. When mean joint length exceeds the electrode spacing, azimuthal resistivity peaks closely coincide with the mean strikes of observed joint sets. When joint lengths are less than the electrode spacing, the major ellipse axis indicates the most conductive path through the joint system. In both cases, ellipse shape indicates the direction (s) having the greatest joint connectivity, which are also the directions of greatest aquifer permeability.
Dichlorobenzene in Ground Water: Evidence for Long‐Term Persistence
Authors: Barber Larry B. 
Published: March 2006

ABSTRACTHydrologic and geochemical evidence were used to establish the long‐term persistence of dichlorobenzene in ground water that has been contaminated from 50 years of rapid‐infiltration sewage disposal. An extensive plume of dichlorobenzene extends more than 3,500 meters down‐gradient from the disposal beds, with concentrations of the combined isomers ranging from less than 0.01 to over 1.0 μglL Based on estimates of maximum ground‐water flow velocities, a minimum age of 20 years was established for the farthest downgradient zone of dichlorobenzene contamination. Branched‐chained, alkylbenzenesulfonic acid surfactants, that were introduced into the ground water prior to 1966, occur along with dichlorobenzene in the downgradient part of the plume, further establishing residence of the compounds in the aquifer for at least 20 years. Although dichlorobenzene can be biologically degraded under aerobic conditions, its persistence at this field site is attributed to the dynamics of the ground‐water system. Denitrifying conditions, resulting from the degradation of organic compounds in the aquifer near the disposal beds, appear to have enhanced the persistence of dichlorobenzene, which is not degraded by anaerobic bacteria. Biological degradation of dichlorobenzene in the aerobic part of the plume downgradient from the source is probably limited by the paucity of a suitable organic‐carbon substrate and the low concentrations of dissolved oxygen in the contaminated ground water.
Conductivity Variations of Formation Waters in Coastal Alluvium, Andhra Pradesh, India
Authors: Subbaraoa C. , Satyanarayanab C. 
Published: March 2006

ABSTRACTGround‐water samples'collected from wells in the coastal alluvial sediments of Andhra Pradesh near the Bay of Bengal have a large variation in conductivity values which can be related to chloride concentration and soil influence. In addition to spatial variation, there appears to be a relationship between the depth to ground‐water level and the conductivity of formation water. Wells with water levels above 3 m have a greater range of conductivity than those with water levels below 3 m.
Modifying the USGS Solute Transport Computer Model to Predict High‐Density Hydrocarbon Migration
Authors: Hossain M. Akhter , Corapcioglu M. Yavuz 
Published: March 2006

ABSTRACTChlorinated hydrocarbons, such as trichloroethylene (TCE), trichloroethane (TCA), tetrachloroethylene (PCE), chloroform, and carbon tetrachloride enter soils and ground water from chemical waste disposal sites and from accidents. The migration of such high‐density hydrocarbons in a natural gradient unconfined gravel aquifer is studied. The Buckley‐Leverett approach is extended to a two‐dimensional case to simulate a high‐density immiscible hydrocarbon displacing ground water in a gravity‐driven system. Governing equations that were developed earlier by Corapcioglu and Hossain (1988) are solved by modifying the U.S.G.S. solute transport model (Konikow and Bredehoeft, 1978). The modification incorporates the fractional flow curves of water and their saturation derivatives in vertical and horizontal directions as functions of degree of water saturation. The details of the modification techniques are given, and the numerical results are presented for a hydrocarbon spill. Numerical results show that high‐density, low‐viscosity immiscible chlorinated hydrocarbons can travel deeper and further in contrast to lower‐density, higher‐viscosity compounds, and that the migration is dominated by gravity largely uncoupled from the horizontal component until the plume reaches the lower boundary.
Time Domain Electromagnetic Soundings for Mapping Sea‐Water Intrusion in Monterey County, California
Authors: Mills Theodore , Hoekstra Pieter , Blohm Mark , Evans Lauren 
Published: March 2006

ABSTRACTIn November 1986, a surface geophysical survey was performed in Monterey County, California using Time Domain Electromagnetic (TDEM) soundings. Prior to this time, the Monterey County Flood Control and Water Conservation District had relied largely on water quality samples from monitoring wells to determine the extent of sea‐water intrusion in the Salinas Valley. This monitoring program had found that of the three aquifers in the study area, two aquifers, the “180‐ft” and the “400‐ft,” had been intruded. The third aquifer, the “900‐ft” aquifer, had not shown signs of sea‐water intrusion. The District decided to use surface geophysics to obtain information about water quality between monitoring wells and to contour the position of the 500‐ppm isochlor in both of the upper aquifers.Because the conductivity of water increases with chloride concentration, electrical methods are well‐suited for mapping chloride concentration in ground water. The TDEM sounding method was selected as the surface electrical measurement technique. It had proven successful for mapping interfaces between fresh water and salt water on surveys in Cape Cod, Massachusetts, in several areas in Florida, and in southern California. A total of 100 soundings were measured in the project area, requiring three weeks of field work. The soundings were located by using the information available from monitoring wells. Lines of soundings were run approximately perpendicular to the anticipated position of the 500‐ppm isochlor to better define the location of the isochlor.Several soundings were measured adjacent to wells to aid in correlating the geophysical interpretations to known water quality data. By correlating the surface geophysics to water quality data from monitoring wells, the position of the 500‐ppm isochlor could be mapped in both the “180‐ft” and “400‐ft” aquifer.The positions of the contours of the 500‐ppm isochlor derived from monitoring wells and from 100 TDEM soundings show excellent agreement. There is more local detail in the isochlor contours derived from geophysical interpretations than in the contours derived from monitoring wells, mainly because of the higher TDEM stations density.
Radon Distribution in Domestic Water of Texas
Authors: Cech Irina , Kreitler Charles , Prichard Howard , Holguin Alfonso , Lemma Mengistu 
Published: March 2006

ABSTRACTConcern is mounting over possible adverse health effects associated with exposure to elevated domestic alpha radiation levels (Bean et al, 1982); Petersen et al., 1966; Lyman et al, 1985; Cothern, 1987). Radon released during domestic use of ground water is one of the potential routes of such exposure. However, relatively little is known worldwide about the distribution of alpha‐emitting radioisotopes in ground‐water supplies. In Texas, deposits of uranium occur, rich enough to be mined commercially, and the possibility existed that significant concentrations of uranium disintegration products may have been present in ground‐water supplies. Cech et al. (1987a) identified two regions with anomalously high concentrations of radium‐226: in the Gulf Coast, downdip from uranium deposits, and in west‐central Texas, on the periphery of an igneous uplift. Radium‐226 is a parent of radon‐222 which is a focus of the present paper. Concentrations of radon up to 3300 pCi/1 were observed in several domestic‐water supplies. This study suggests that it may be external sources (interaction of Tertiary aquifers with salt domes, leaky faults, and uranium‐bearing volcanic ashes) and not the bulk mineralogy of the aquifers, which cause anomalous concentrations of alpha‐emitting radioisotopes in well water. The distinction is important, as it offers the possibility of avoiding high risk areas when selecting well drilling locations.
The Recharge‐Discharge Function of Wetlands Near Juneau, Alaska: Part II. Geochemical Investigations
Authors: Siegel D. I. 
Published: March 2006

ABSTRACTThe recharge‐discharge function of bogs, fens, and forested wetlands near Juneau, Alaska, was investigated by comparing concentrations of solutes and measurements of specific conductance in wetland ground water and surface water. Average concentrations of major metals define major wetland types. Bogs and fens are in recharge areas and have the most dilute ground water. Forested wetlands are in discharge areas and have ground‐water chemistry similar to that found in domestic wells completed in mineral soils.Concentration profiles of total dissolved metals in blanket bogs were compared to theoretical concentration profiles based on the diffusion of solutes from mineral soil into the overlying peat. All observed concentration profiles are less than predicted by diffusion, and show that the blanket bogs are long‐term recharge zones.
Interpretation of Well and Field Data in a Heterogeneous Layered Aquifer Setting, Appalachian Plateau
Authors: Booth Colin J. 
Published: March 2006

ABSTRACTGround‐water flow systems in the Appalachian Plateau coalfield balance the conflicting controls of topographic relief and hydrostratigraphic layering. Appropriate use of field observations (springs, streams) and abundant domestic well information (water levels, pumping test results, records of yield, and water‐producing zones) helped resolve ambiguities about a typical system in Cambria County, Pennsylvania. The effective scale for hydrostratigraphic division is by sandstone‐dominated members as aquifers and intervening shale‐clay members as aquitards. The flow system is stratified in the intervalley ridges; heads, controlled primarily by the dissected aquifer outcrop, drop discretely to lower aquifers. Discrete ground‐water discharge and lateral head changes indicate local heterogeneity, enhanced by mine‐subsidence effects. The principal valleys carry a topographically controlled system, for which they serve as recharge feeders.
Numerical Modeling of Salt‐Water Intrusion at Hallandale, Florida
Authors: Andersen Peter F. , Mercer James W. , White Harold O. 
Published: March 2006

ABSTRACTThe City of Hallandale, located on the east coast of Florida, has documented over the past decade an increase in chloride in the monitoring well network surrounding its wellfield. Data indicate that the salt‐water front is currently located within 1,200 ft of the wellfield and is still moving inland. Suspected causes of the intrusion are: (1) increased pumpage by Hallandale, (2) increased pumpage from neighboring wellfields, (3) cumulative deficiency in rainfall over the past decade, and (4) reduction of canal stages that control water‐table elevations. The inability of standard methods to characterize the salt‐water intrusion led to the use of numerical modeling to aid in understanding the processes occurring at Hallandale. A series of three models were used in the study. A cross‐sectional model was used to conceptualize the flow system, and a regional model synthesized input for the third model, the wellfield model. The wellfield model was eventually used to assess the relative merits of proposed water management alternatives. Although the modeling did not isolate a specific cause of the intrusion, it did show the extreme sensitivity of the hydrologic system. Long‐term water‐level declines of only a few tenths of a foot were shown to result in a significant movement of the salt‐water front. There is a distinct time lag, however, between lowering of the hydraulic heads and movement of the salt‐water front, which has many implications for water management decisions and in the construction and calibration of a numerical model. These observations, as well as others made in the course of this study, can be applied generally to coastal water management programs.
Infection withPlasmodium bergheiBoosts Antibody Responses Primed by a DNA Vaccine Encoding Gametocyte Antigen Pbs48/45
Authors: Haddad Diana , Maciel Jorge , Kumar Nirbhay 
Published: March 2006

ABSTRACTAn important consideration in the development of a malaria vaccine for individuals living in areas of endemicity is whether vaccine-elicited immune responses can be boosted by natural infection. To investigate this question, we usedPlasmodium bergheiANKA blood-stage parasites for the infection of mice that were previously immunized with a DNA vaccine encoding theP. bergheisexual-stage antigen Pbs48/45. Intramuscular immunization in mice with one or two doses of DNA-Pbs48/45 or of empty DNA vaccine as control did not elicit detectable anti-Pbs48/45 antibodies as determined by enzyme-linked immunosorbent assay. An infection withP. bergheiANKA 6 weeks after DNA vaccination elicited comparable anti-Pbs48/45 antibody levels in mice which had been primed with DNA-Pbs48/45 or with empty DNA vaccine. However, a repeat infection withP. bergheiANKA resulted in significantly higher anti-Pbs48/45 antibody levels in mice which had been primed with the DNA-Pbs48/45 vaccine than the levels in the mock DNA-vaccinated mice. In parallel and as an additional control to distinguish the boosting of Pbs48/45 antibodies exclusively by gametocytes during infection, a separate group of mice primed with DNA-Pbs48/45 received an infection withP. bergheiANKA clone 2.33, which was previously described as a “nongametocyte producer.” To our surprise, this parasite clone too elicited antibody levels comparable to those induced by theP. bergheigametocyte producer clone. We further demonstrate that the nongametocyte producerP. bergheiclone is in fact a defective gametocyte producer that expresses Pbs48/45, much like the gametocyte producer clone, and is therefore capable of boosting antibody levels to Pbs48/45. Taken together, these results indicate that vaccine-primed antibodies can be boosted during repeat infections and warrant further investigation with additional malaria antigens.
Contribution of Hemagglutinin/Protease and Motility to the Pathogenesis of El Tor Biotype Cholera
Authors: Silva Anisia J. , Leitch Gordon J. , Camilli Andrew , Benitez Jorge A. 
Published: March 2006

ABSTRACT

Vibrio cholerae
is a highly motile organism that secretes a Zn-dependent metalloprotease, hemagglutinin/protease (HapA). HapA has been shown to have mucinase activity and contribute to the reactogenicity of live vaccine candidates, but its role in cholera pathogenesis is not yet clear. The contribution of motility to pathogenesis is not fully understood, since conflicting results have been obtained with different strains, mutants, and animal models. The objective of this work was to determine the contribution of HapA and motility to the pathogenesis of El Tor biotype cholera. To this end we constructed isogenic motility (
motY
) and mucinase (
hapA
) single and double mutants of an El Tor biotype
V. cholerae
strain. Mutants were characterized for the expression of major virulence factors in vitro and in vivo. The motility mutant showed a remarkable increase in cholera toxin (CT), toxin coregulated pilus major subunit (TcpA), and HapA production in vitro. Increased TcpA and CT production could be explained by increased transcription of
tcpA
,
ctxA
, and
toxT
. No effect was detected on the transcription of
hapA
in the motility mutant. The sodium ionophore monensin diminished production of HapA in the parent but not in the motility mutant. Phenamil, a specific inhibitor of the flagellar motor, diminished CT production in the wild-type and
motY
strains. The
hapA
mutant showed increased binding to mucin. In contrast, the
motY
mutation diminished adherence to biotic and abiotic surfaces including mucin. Lack of HapA did not affect colonization in the suckling mouse model. The motility and mucinase defects did not prevent induction of
ctxA
and
tcpA
in the mouse intestine as measured by recombinase-based in vivo expression technology. Analysis of mutants in the rabbit ileal loop model showed that both
V. cholerae
motility and HapA were necessary for full expression of enterotoxicity.
Genetic Resistance toBrucella abortusin the Water Buffalo (Bubalus bubalis)
Authors: Borriello Giorgia , Capparelli Rosanna , Bianco Michele , Fenizia Domenico , Alfano Flora , Capuano Federico , Ercolini Danilo , Parisi Antonio , Roperto Sante , Iannelli Domenico 
Published: March 2006

ABSTRACTBrucellosis is a costly disease of water buffaloes (Bubalus bubalis). Latent infections and prolonged incubation of the pathogen limit the efficacy of programs based on the eradication of infected animals. We exploited genetic selection for disease resistance as an approach to the control of water buffalo brucellosis. We tested 231 water buffalo cows for the presence of anti-Brucella abortusantibodies (by the agglutination and complement fixation tests) and theNramp1genotype (by PCR-denaturing gradient gel electrophoresis). When the 231 animals (58 cases and 173 controls) were divided into infected (seropositive) and noninfected (seronegative) groups and theNramp1genotypes were compared, the seropositive subjects were 52 out of 167 (31%) in theNramp1A+(Nramp1AAorNramp1AB) group and 6 out of 64 (9.4%) in theNramp1A−(Nramp1BB) group (odds ratio, 4.37; 95% confidence limits, 1.87 to 10.19; χ2, 11.65 for 1 degree of freedom). Monocytes fromNramp1BBsubjects displayed significantly (P< 0.01) higher levels ofNramp1mRNA thanNramp1AAsubjects and also a significantly (P< 0.01) higher ability in controlling the intracellular replication of severalBrucellaspecies in vitro. Thus, selection for theNramp1BBgenotype can become a valuable tool for the control of water buffalo brucellosis in the areas where the disease is endemic.
NF-κB-Inducing Kinase Regulates Selected Gene Expression in the Nod2 Signaling Pathway
Authors: Pan Qilin , Kravchenko Vladimir , Katz Alex , Huang Shuang , Ii Masayuki , Mathison John C. , Kobayashi Koichi , Flavell Richard A. , Schreiber Robert D. , Goeddel David , Ulevitch Richard J. 
Published: March 2006

ABSTRACT

The innate immune system surveys the extra- and intracellular environment for the presence of microbes. Among the intracellular sensors is a protein known as Nod2, a cytosolic protein containing a leucine-rich repeat domain. Nod2 is believed to play a role in determining host responses to invasive bacteria. A key element in upregulating host defense involves activation of the NF-κB pathway. It has been suggested through indirect studies that NF-κB-inducing kinase, or NIK, may be involved in Nod2 signaling. Here we have used macrophages derived from primary explants of bone marrow from wild-type mice and mice that either bear a mutation in NIK, rendering it inactive, or are derived from NIK
−/−
mice, in which the NIK gene has been deleted. We show that NIK binds to Nod2 and mediates induction of specific changes induced by the specific Nod2 activator, muramyl dipeptide, and that the role of NIK occurs in settings where both the Nod2 and TLR4 pathways are activated by their respective agonists. Specifically, we have linked NIK to the induction of the B-cell chemoattractant known as BLC and suggest that this chemokine may play a role in processes initiated by Nod2 activation that lead to improved host defense.
Reduced Protective Efficacy of a Blood-Stage Malaria Vaccine by Concurrent Nematode Infection
Authors: Su Zhong , Segura Mariela , Stevenson Mary M. 
Published: March 2006

ABSTRACT

Helminth infections, which are prevalent in areas where malaria is endemic, have been shown to modulate immune responses to unrelated pathogens and have been implicated in poor efficacy of malaria vaccines in humans. We established a murine coinfection model involving blood-stage
Plasmodium chabaudi
AS malaria and a gastrointestinal nematode,
Heligmosomoides polygyrus
, to investigate the impact of nematode infection on the protective efficacy of a malaria vaccine. C57BL/6 mice immunized with crude blood-stage
P. chabaudi
AS antigen in TiterMax adjuvant developed strong protection against malaria challenge. The same immunization protocol failed to induce strong protection in
H. polygyrus
-infected mice. Immunized nematode-infected mice produced significantly lower levels of malaria-specific antibody than nematode-free mice produced. In response to nematode and malarial antigens, spleen cells from immunized nematode-infected mice produced significantly lower levels of gamma interferon but more interleukin-4 (IL-4), IL-13, and IL-10 in vitro than spleen cells from immunized nematode-free mice produced. Furthermore,
H. polygyrus
infection also induced a strong transforming growth factor β1 response in vivo and in vitro. Deworming treatment of
H. polygyrus
-infected mice before antimalarial immunization, but not deworming treatment after antimalarial immunization, restored the protective immunity to malaria challenge. These results demonstrate that concurrent nematode infection strongly modulates immune responses induced by an experimental malaria vaccine and consequently suppresses the protective efficacy of the vaccine against malaria challenge.