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Shear (S) wave velocities derived from the MASW (multi-channel analysis of surface wave) technique and borehole measurements at seven well locations in unconsolidated sediments of the Fraser River Delta are compared. The overall difference between these two sets of S-wave velocities is about 15%. S-wave velocities from the MASW technique at an additional location are also obtained and await comparison with borehole measurements.

Ground roll is displayed, on an uncorrelated field record obtained using a monotonic sweep, in increasing or decreasing order of frequency with each frequency well separated from all others. Phase velocity and attenuation characteristics of each frequency contain the average elastic property of near-surface materials down to approximately half the wavelength. Uncorrelated field record, therefore, by itself can be associated with a two-dimensional display of the change in near-surface elastic property. Through the redundancy in data acquisition and a simple data processing step, the uncorrelated field records can be transformed into a stacked section that can be correlated directly to image of the change in elastic property of near-surface materials with respect to a certain reference location. This method can be effectively used to detect near-surface anomalies of various kinds.

The shallow shear-wave refraction method works successfully in an area with a series of horizontal layers. However, complex near-surface geology may not fit into the assumption of a series of horizontal layers. That a plane SH-wave undergoes wave-type conversion along an interface in an area of nonhorizontal layers is theoretically inevitable. One real example shows that the shallow shear-wave refraction method provides velocities of a converted wave rather than an SH-wave. Moreover, it is impossible to identify the converted wave by refraction data itself. As most geophysical engineering firms have limited resources, an additional P-wave refraction survey is necessary to verify if velocities calculated from a shear-wave refraction survey are velocities of converted waves. The alternative at this time may be the surface wave method, which can provide reliable S-wave velocities, even in an area of velocity inversion (a higher velocity layer underlain by a lower velocity layer).

Legionella pneumophila causes Legionnaires’ disease by replication in alveolar macrophages and monocytes. The bacteria are internalized most efficiently by opsonin-dependent, CR3-mediated phagocytosis. This investigation focused on determining the role of actin polymerization and phosphorylation signals in this uptake mechanism. Uptake inhibition assays and confocal microscopic analysis indicated that entry of L. pneumophila activated tyrosine kinase (TK) and protein kinase C (PKC) and induced actin polymerization at the site of bacterial entry. Upon L. pneumophila entry, six major cellular proteins (75, 71, 59, 56, 53, and 52 kDa) were TK phosphorylated in soluble fractions of monocytes, and three of these proteins (52, 53, and 56 kDa) were consistently found in insoluble (i.e., cytoskeletal) fractions of monocytes as well. Tyrosine phosphorylation was suppressed when cells were pretreated with the kinase inhibitor genistein, tyrphostin, or staurosporine. A similar tyrosine-phosphorylated protein pattern was observed with CR3-mediated entry of avirulent L. pneumophila , Escherichia coli , or zymosan into monocytes. This study has shown that PKC and TK signals which activate actin polymerization during the process of phagocytosis are induced upon L. pneumophila entry. In addition, CR3 receptor-mediated phagocytosis into monocytes may involve tyrosine phosphorylation of similar proteins, regardless of the particle being phagocytosed. Therefore, the tyrosine-induced phosphorylation observed during opsonized L. pneumophila entry is not a virulence-associated event.

Interferon-gamma (IFN-gamma) induces tryptophan catabolism in HEp-2 cells, possibly via stimulation of host cell indoleamine-2,3-dioxygenase activity, in a dose-dependent (12.5-1600 U/mL) fashion after 24 h, resulting in a 99% conversion to its metabolites at 1600 U/mL. Replication of Chlamydia pneumoniae isolates A-03 and BAL-16 was inhibited in HEp-2 cells following treatment with 50 and 100 U/mL IFN-gamma, respectively; however, addition of excess L-tryptophan (200 microg/mL) to monolayers infected with C. pneumoniae resulted in unrestricted growth of both isolates up to 1600 U/mL IFN-gamma. C. pneumoniae could be recovered from IFN-gamma-treated monolayers, indicating the potential for this bacterium to undergo an altered life cycle, in vitro, analogous to that described in detail for Chlamydia trachomatis. The ability of C. pneumoniae to persist in host tissue despite an immunologic response would be an important attribute in order to cause or exacerbate chronic infections.

Summary Shallow seismic reflection has seen widespread use in a variety of environmental, groundwater, and engineering applications over the last 15 years. Seismic reflection, like any other geophysical technique, has reasonably well defined limitations. Besides the well-published resolution limitation, the effectiveness of the technique is strongly dependent, and in many cases controlled, by near-surface conditions. Moisture content, sorting, grain size, organic matter, and consolidation are just a few of the key properties of the near-surface that can dramatically affect the quality of seismic reflection data. In some difficult data areas thoughtful parameter design, high-quality equipment (large dynamic range and small electronic noise), and careful processing can overcome adverse near-surface c onditions. Tendencies to suggest that data processing is the key to bringing out reflections on CMP stacks that are not identifiable on shot or CMP gathers leads to overselling the technique and inevitable skepticism by clients and potential clients as to the reliability of shallow seismic reflection. As difficult as it may be for shallow seismic reflection practitioners to admit, shallow seismic reflection simply will not work in some settings and for some targets.

Summary Real and synthetic data verifies the wavefield transformation method described here converts surface waves on a shot gather directly into images of multi-mode dispersion curves. Pre-existing multi-channel processing methods require preparation of a shot gather with exceptionally large number of traces that cover wide range of source-to-receiver offsets for a reliable separation of different modes. This method constructs high-resolution images of dispersion curves with relatively small number of traces. The method is best suited for near-surface engineering project where surface coverage of a shot gather is often limited to near-source locations and higher-mode surface waves can be often generated with significant amount of energy.

On an uncorrelated field record obtained using a monotonic sweep, ground roll is displayed in increasing or decreasing order of frequency with each frequency well separated from all others. Phase velocity and attenuation characteristics of each frequency contain the average elastic property of nearsurface materials down to approximately half the wavelength. An uncorrelated field record, therefore, by itself can be associated with a two-dimensional display of the change in near-surface elastic property. Through the redundancy in data acquisition and a simple data processing step, the uncorrelated field records can be transformed into a stacked section that can be correlated directly to the image of the change in elastic property of near-surface materials. This method can be effectively used to detect near-surface anomalies of various kinds.

Summary High frequency random noise can be attenuated in the F-k domain using Stolt F-k migration. F-k migration algo rithms routinely used to effectively migrate data can be used to attenuate high frequency random noise. The attenuation of high frequency random noise in the F-k domain is facilitated by defining the trace spacing interval signi ficantly larger or velocity significantly lower than actual. Evaluation of this noise attenuation technique on real data conclusively shows significant improvement in data co herency and a decrease in high frequency random noise with no noticeable migration effects or artifacts. The method seems especially useful in situations where migra tion produces artifacts, high frequency random noise is present or where techniques such as spectral balancing have left an elevated level of background noise.

Politicians and scientists continue debating the reality of global climate change. What had long been thought of as science fiction or only the ramblings of extremists has become the focus of multidisciplinary research endeavors involving a large segment of the world's scientific and engineering community. The technical challenges of intentionally altering the global climate have stirred the curiosity and imaginations of many researchers.

Seventeen different species of Legionella, 12 serogroups of Legionella pneumophila, and 2 Legionella-like amoebal pathogens (LLAP1 and Sarcobium lyticum) were examined by heteroduplex analysis of PCR products of the 5S rRNA gene. Eight different banding patterns were identified, indicating that heteroduplex analysis of this gene can be used to classify these bacteria according to base substitutions between species. This classification may have future applications in clinical and epidemiological studies.

In this study, five non-invasive swept sources, three non-invasive impulsive sources and one invasive impulsive source were compared. Previous shallow seismic source tests (Miller and others, 1986, 1992, 1994) have established that site characteristics should be considered in determining the optimal source. These studies evaluated a number of invasive sources along with a few non-invasive impulsive sources. Several sources (particularly the high frequency vibrators) that were included in the ORR test were not available or not practical during previous tests, cited above. This study differs from previous source comparisons in that it (1) includes many swept sources, (2) is designed for a greater target depth, (3) was conducted in a very different geologic environment, and (4) generated a larger and more diverse data set (including high fold CMP sections and walkaway vertical seismic profiles) for each source. The test site is centered around test injection well HF-2, between the southern end of Waste Area Grouping 5 (WAG 5) and the High Flux Isotope Reactor (HFIR).

The advantages of 3-D seismic imaging are well founded for petroleum applications. Significant potential exists for this technique in delineating targets critical to shallow site characterization. The high cost and high technology nature as well as many assumptions appropriate for deeper petroleum problems are not realistic or feasible for near surface applications. A low fold, minimal cost 3-D survey designed around common offset and shallow seismic reflection techniques at a salt dissolution sinkhole in central Kansas provided valuable insight into the effectiveness and potential of minimal deployment 3-D surveys to delineate major structural features. Volumetric display enhanced the interpretability of this low cost but effective 3-D survey.

Though carbonate rocks make up only 20% of the sedimentary rock record, carbonate reservoirs hold 60% of the world's petroleum reserves and presently account for 40% of the world's total hydrocarbon production. Because of this obvious mismatch between potential and current production, our industry has recognized the need to understand carbonate reservoirs better and be able to produce them more efficiently. The emphasis is likely to continue and grow in the future.

For nearly a decade now, SEG has actively and purposely scanned the horizon looking for opportunities to increase its offerings to and its support of the global applied geophysical community. Vision and flexibility have proven key to optimally positioning the Society for meeting member needs in a timely fashion. SEG's vision continues to be broadband with both near-term (on the order of years) and long-term (looking decades ahead of us) goals. It is imperative that we remain focused while cherry-picking our way through the range of opportunities routinely bombarding our Society. Staff and volunteers guided by a balanced and prioritized plan leads to proactive, rather than reactive, decisions.

Diagnosis of Mycoplasma pneumoniae and Chlamydia pneumoniae lower respiratory infections using DNA amplification by polymerase chain reaction (PCR) on throat swab specimens has been reported. In this study we determined the sensitivity of the detection of Legionella pneumophila in simulated throat swab specimens by PCR. Next, we compared the sensitivity and specificity of a single throat swab PCR with the current tests for diagnosis of Legionella spp., M. pneumoniae, and C. pneumoniae in patients with lower respiratory tract infections. Patients' work-up included: (a) throat swab specimen for Legionella spp., M. pneumoniae, and C. pneumoniae PCR; (b) throat swab specimen for C. pneumoniae culture; (c) sputum specimen for L. pneumophila direct fluorescent antibody and culture; (d) urine specimen for L. pneumophila serogroup 1 antigen detection; and (e) serum specimen for L. pneumophila, M. pneumoniae, and C. pneumoniae acute and convalescent antibody titers. A total of 155 patients with lower respiratory infection were enrolled in this prospective study. Throat swab PCR was positive for Legionella spp. in five of the six patients with legionellosis, indicating the presence of this organism in the oropharynx of patients with Legionnaires disease. Mycoplasma pneumoniae PCR was positive in eight of the nine patients with mycoplasma infection. Chlamydia pneumoniae PCR was positive in the two patients with C. pneumoniae infection. None of the other 138 patients with negative PCR had other positive confirmatory tests for respiratory infection by these three organisms (100% specificity). PCR was able to detect 15 of the 17 infected (88.2%). Results of this investigation indicate that PCR on a single throat swab specimen is a rapid, sensitive, and specific test that may greatly simplify the diagnosis of lower respiratory infection caused by Legionella spp., Mycoplasma pneumoniae, or C. pneumoniae.

The effectiveness of shallow high resolution ‘seismic reflection (i.e., resolution potential) to image geologic interfaces between about 70 and 750 ft at the Aberdeen Proving Grounds, Maryland (APG), appears to vary locally with the geometric complexity of the unconsolidated sediments that overlay crystalline bedrock. The bedrock surface (which represents the primary geologic target of this study) was imaged at each of three test areas on walkaway noise tests and CDP (common depth point) stacked data. Proven high resolution techniques were used to design and acquire data on this survey. Feasibility of the technique and minimum acquisition requirements were determined through evaluation and correlation of walkaway noise tests, CDP survey lines, and a downhole velocity check shot survey. Data processing and analysis revealed several critical attributes of shallow seismic data from APG that need careful consideration and compensation on reflection data sets. This survey determined: 1) the feasibility of the technique, 2) the resolution potential (both horizontal and vertical) of the technique, 3) the optimum source for this site, 4) the optimum acquisition geometries, 5) general processing flow, and 6) a basic idea of the acoustic variability across this site. Source testing involved an accelerated weight drop, land air gun, downhole black powder charge, sledge hammer/plate, and high frequency vibrator. Shallow seismic reflection profiles provided for a more detailed picture of the geometric complexity and variability of the distinct clay sequences (aquatards), previously inferred from drilling to be present, based on sparse drill holes and basewide conceptual models. The seismic data also reveal a clear explanation for the difficulties previously noted in correlating individual, borehole-identified sand or clay units over even short distances. Geologic cross-sections derived from CDP stacked data and borehole logs suggest locally complex geometries and horizontally variable geologic contacts.

Some of the most significant developments in the last 40 years in near-surface geophysics have come from a small core of geophysicists relentlessly working to adapt, engineer, and push existing theory and practice in a direction not previously considered or thought practical. This creativity and tenacity has generally focused on providing solutions to specific problems in a geologically difficult or challenging setting where the economic climate and target depths make a backhoe and auger drill competing technologies.

S U M M A R Y Edge effects are distortions at the edge of a domain which are artifacts of the implicit assumptions of a numerical algorithm or of the limited span of data used to solve the problem (Sheriff, 1991, p. 96). During wavenumber domain filtering of potential-field data, (e.g., reduction to the pole, pseudogravity, and directional derivative, etc.), edge effect distortions are usually parallel to the boundaries of the data set. Amplitudes of these artifacts could be several times the maximum amplitude of the real anomalies in the data. A conventional processing method results in distortion of up to twenty-five percent of the data points. We use an approach developed by Xia et al. (1993) for determining equivalent sources and then calculating specific anomalies based upon these equivalent sources. A synthetic example shows that edge effects are reduced to a negligible level when the reduced-tothe-pole operator is applied to magnetic anomalies. We also apply the reduced-to-the-pole operator to aeromagnetic data in Kansas, which gives a satisfactory result

Many commonly used shallow seismic sources are unacceptable for hazardous waste site investigations because they risk exhumation of contaminants in the soil, they add contaminants (e.g. lead) which are not allowed by regulations, or they add new migration paths for contaminants. Furthermore, recently developed high frequency vibrators for shallow investigations could be more effective at some sites than non-invasive impulsive sources because of their ability to tailor the source spectrum and reduce interference. The authors show preliminary results of a comparison test of eight non-invasive impulsive and swept sources in preparation for seismic reflection profiling on the Oak Ridge Reservation, Tennessee. Well log data are used to determine geologic contacts and to generate synthetic seismograms for the site. Common midpoint (CMP) seismic data for each source were collected at 95 geophone groups from 125 shot points along a 400m test line. Hydrophone data were obtained at 1.5m spacing between 61m and 133m depth in a hole near the center of the CMP line. As of March, 1994, brute stacks have been completed for three of the eight sources. Depth penetration is demonstrated in brute stacks and shot gathers, which show a 200ms reflector for all of the sources tested alongmore » portions of the line. Source effectiveness will also be evaluated by comparing images of several shallower reflectors (40--150ms) which are apparent in many of the records. Imaging of these reflectors appears to depend upon the ability of the source to generate sufficient high frequency energy (>100 Hz).« less

Shallow high resolution 2-D and 3-D seismic reflection techniques are assisting in the subsurface delineation of a surface collapse feature (sinkhole) at Weeks Island, Louisiana. Seismic reflection surveys were conducted in March 1994. Data from walkaway noise tests were used to assist selection of field recording parameters. The top of the salt dome is about 180 ft below ground surface at the sinkhole. The water table is an estimated 90 ft below the ground surface. A single coherent reflection was consistently recorded across the entire area of the survey, although stacking velocity and spectral content of the event varied. On the basis of observed travel times and stacking velocities, the coherent reflection event appears to originate above the top of the salt, possibly at or near the water table. Identification of this reflector will be made form borehole investigations currently planned for the sinkhole site. A depression or time sag in this reflection event is clearly evident in both the 2-D and 3-D seismic data in the immediate vicinity of the sinkhole. The time sag appears to be related to the subsurface structure of the reflector and not to near surface topography or velocity effects. Elsewhere in the survey area,more » observed changes in reflection travel times and wavelet character appear to be related to subsurface geologic structure. These seismic observations may assist in predicting where future sinkholes will develop after they have been tied to borehole data collected at the site.« less

Substantial progress has occurred during the past 15 years in development of shallow CDP seismic-reflection techniques, but there are occasional interpretation problems with the resulting data. We discuss examples of the pitfalls of the method, along with some procedures to help avoid them. Problems that often occur include spatial aliasing of ground roll, interpreting processed ground-coupled air waves as true seismic waves, misinterpreting refractions as reflections on stacked CDP sections, and not recognizing processing artifacts. Aliasing occurs when data are not sampled often enough in time and/or space. Decreasing the geophone interval by a substantial amount (such as a factor of two) will improve coherency of a true reflector, but will destroy coherency of spatially aliased ground roll. It is often difficult to separate shallow reflections from shallow refractions during processing. Reflected energy from shallow depths tends to have frequency content close to that of the direct wave and/or early refracted arrivals on field seismograms. Refractions on a stacked section tend to be a bit lower in frequency because the NM0 correction in a CDP stack assumes hyperbolic moveout, while refractions arrive as a linear time-distance function. Hence, they don’t stack as coherently as reflections, which decreases their frequency. Processing artifacts from inadequate velocity analysis and inaccurate static corrections are at least as troublesome on shallow reflection sections as they are on classical reflection surveys from petroleum exploration. It has been our experience that occasional field records will display unusually good reflections. These field seismograms can be used to correlate to the processed seismic sections. Unequivocally separating shallow reflections from shallow refractions is clearly one of the major limitations of the shallow-seismic reflection method at present.

Research has been undertaken at the Kansas Geological Survey (KGS), the University of Kansas, to develop a new type of coded impulsive seismic technique that could generate reflection data with a high resolution comparable (or superior) to that of the Mini-Sosie technique in a more efficient manner. A deterministic coding model has been developed for use with an impulsive seismic source. High-resolution reflection data are obtained after decoding and stacking to increase signal-to-noise (S/N) ratio. Although there are several other choices for the deterministic coding mode, the code used in this paper consists of a “linear” sequence of timebreaks (the impact times) in which the interval between two consecutive timebreaks decreases linearly with time. The auto-correlation function of the code sequence suggests that the form of the correlation noise (Barbier, 1982, p. 55) will be much less troublesome than that in the Mini-Sosie technique. In addition, the power spectrum of the code sequence suggests that the correlation noise itself can be used as a filter to suppress low-frequency large-amplitude noise events such as ground roll and first breaks, while boosting high-frequency components of the reflection events. Because it is a deterministic method, the expected results are obtainable with least ambiguity within a short time duration. Experiments using synthetic data sets show that the technique could lead to an efficient new high-resolution source.

The role of nitric oxide (NO) radicals in killing the intracellular bacterial pathogen Legionella pneumophila (Lp) was examined in infected macrophages. Murine (RAW 264.7) and human (HL-60) cell monolayers were treated with 100 U/mlγ-interferon (IFN) and cocultured with Lp in the presence and absence of NGMMA, a specific inhibitor of NO production. Viable Lp in IFN-treated RAW 264.7 cells decreased from 3.8 to 0.7 ± 0.12 log CFU/ml after 24 h incubation, whereas in IFN + NGMMA-treated RAW 264.7 cells, viable Lp persisted at 2.2 ± 0.2 log CFU/ml after 24 h. This increased survival corresponded with an inhibition of NO production (5.65 ± 2.99 μM with NGMMA vs. 58.6 ± 5.36 μM without NGMMA). Viable Lp were susceptible to killing, in a dose-dependent fashion, by 0, 2.5, and 5.0 mM sodium nitroprusside, a source of NO radicals. IFN-treated RAW 264.7 cells also had significantly decreased levels of intracellular iron (below assay limit) when compared to IFN + NGMMA-treated cells (72.0 ± 0.78 % of control). Normally permissive HL-60 cells treated with IFN were bacteriostatic rather than bactericidal, and NO production was not detected above background. Thus, NO radicals play a critical role in the bactericidal activity against Lp by IFN-treated RAW 264.7 cells, but the absence of NO production limits IFN-treated HL-60 cells to bac- teriostasis.

A method of preparing teeth to accommodate intracoronal attachments is presented. The resulting prosthesis incorporates a fixed partial denture with physiologically contoured crowns and a removable partial denture with a precisely determined path of insertion. These techniques stress the importance of surveyed diagnostic casts and coordinated tooth preparations for artificial crowns to facilitate treating complex cases.

To assess bacteriolysis in human neonates, Escherichia coli O7w:K1:NM were incubated with sera from eight healthy neonates, serum pooled from the eight neonates, and serum pooled from healthy adults. The adult serum killed E. coli. In contrast, the bacteria were not killed during incubation with sera from the eight neonates, the pooled neonatal serum, or with heat-inactivated adult serum. However, the combination of pooled neonatal serum and heat-inactivated adult serum killed the bacteria. Supplemental IgG-containing antibodies that bound to E. coli did not enhance the bactericidal activity of the neonatal serum. Ten of 12 blood isolates of E. coli from septic neonates but only 8 of 15 isolates from septic adults were serum-sensitive (killed during incubation with adult serum) (P less than .05). Therefore, neonatal serum killed E. coli inefficiently and was deficient in non-IgG heat-stabile component(s) required for bacterial killing. Compared with adults, neonates were more frequently septic with serum-sensitive strains of E. coli.

Shallow seismic reflection profiling was successful in delineating a shallow impermeable layer acting to perch fluids at depths ranging from 125 to 175 ft. The near-surface material was dry dune sands with varying grades of sands and gravels within the upper 20 ft. The seismic data possessed dominant frequencies in excess of 150 Hz resulting in bed resolution on the order of 3 ft at depths less than 150 ft. Several key hydrogeologic features were identified and their significance more completely ascertained using the reflection data.

Shallow high-resolution reflection surveys can be used to study hydrocarbon reservoir analogs on a scale of 1 m vertically and 5 m horizontally. This scale is two orders of magnitude up from laboratory specimens and two orders of magnitude down from typical production reservoirs. A 12-fold CDP survey designed to determine practical resolution limits imaged geometric changes in an oolitic limestone near Independence, Kansas, at a depth of approximately 75 m. The dominant frequency of the stacked data is in excess of 180 Hz. The predicted resolution limits at this site, according the the l/$-wavelength criterion, is on the order of 2 to 3 m. Practical resolution limits at this site could be as small as 1 to 1 l/2 m. Seismic reflection can be utilized at this site to accurately place stratigraphic core drilling holes for determining depositional environments and geologic processes responsible for the present geologic setting.

Environmental waters are monitored for selected pathogens and indicator bacterial populations to ensure the safety of potable water supplies, to establish appropriate disinfection procedures, and to determine the sources of waterborne infectious disease outbreaks.

An improved design of the buffalo gun, incorporating hole drilling and shooting into one operation with almost total blast containment, provided nearly 50 percent more recordable seismic signal than the traditional buffalo gun. The ‘auger gun’ is designed to optimize field efficiency, source couple, and safety. The auger gun consists of three main parts: power source, auger/screw, and modified buffalo gun. Amplitude spectra indicate the auger gun delivers approximately 20 percent more total energy and 50 percent more reflection energy with no noticeable increase in recorded ground roll at a test site in Lawrence, Kansas. Subtle changes in source environment, such as a 15 cm gap between the detonation point and the base of the hole or inclusion of water as opposed to air at the detonation point, have a significant effect on the quality of the recorded data. The auger gun should increase field efficiency by over 50 percent on most shallow surveys, while improving the signal-to-noise ratio and total energy in comparison to the buffalo gun.

Near-surface geophysics has throughout its history enjoyed success at both ends of the exploration geophysics evolutionary chart as a benefactor and contributor. Almost all near-surface methods are traceable to or from petroleum exploration. Noteworthy examples are captured in works by such pioneers as Howell, Kean, and Thompson, who in 1940 were the first to experiment with seismic energy above 2 kHz using a loud speaker; or Evison's 1952 paper where he describes the inadequacies of conventional seismic for imaging shallow targets; or Jakosky, who in his 1938 paper went the other direction, extending the principally shallow groundwater and mining-based exploration capabilities of electrical methods to petroleum targets.

Geophysicists since Karcher have been striving to improve resolution—to see thinner beds, to image smaller faults, and to detect lateral changes in lithology or rock property. The classic definition of resolution, provided by Bob Sheriff, is “The ability to separate two features which are very close together. The minimum separation of two bodies before their individual identities are lost on the resultant map or cross-section.”

The story of “Multichannel analysis of surface waves to map bedrock” was based on a project of opportunity. Surface waves have always been the bane of near-surface reflection seismologists, even more so than petroleum exploration seismologists because of the close offsets and small two-way traveltimes we routinely deal with. With the development of MASW at the Kansas Geological Survey in the mid-1990s, surface waves have proven their utility as signal rather than noise on multichannel seismograms used for many near-surface applications. Extending the original 1D velocity estimation method to a 2D imaging and mapping technique was first demonstrated in this article. Prior to this paper, the utility, accuracy, and precision of the newly developed MASW method to estimate 1D shear-wave velocity functions had been demonstrated in several studies and publications. One of the most significant of these studies was a field test in the Vancouver, Canada area, orchestrated by Jim Hunter of the Geological Survey of C...

Methods were developed for the detection of Legionella in environmental water sources, based upon the polymerase chain reaction (PCR) and gene probes. All species of Legionella, including all 15 serogroups of L. pneumophila tested, were detected by PCR amplification of a 104 bp DNA sequence that codes for a region of 5S rRNA followed by radiolabelled oligoprobe hybridization to an internal region of the amplified DNA. Strains of L. pneumophila (all serogroups) were specifically detected based upon amplification of a portion of the coding region of the macrophage infectivity potentiator (mip) gene. Pseudomonas spp. that exhibit antigenic cross-reactivity in serological detection methods did not produce positive signals in the PCR-gene probe method using Southern blot analyses. Single cell, single gene Legionella detection was achieved with the PCR-gene probe methods.