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Showing papers by "University of Oklahoma published in 1997"


Journal ArticleDOI
TL;DR: Theory suggests and results show that firm performance is initially positive but eventually levels off and becomes negative as international diversification increases as mentioned in this paper, and product diversification moderates firm performance.
Abstract: Theory suggests and results show that firm performance is initially positive but eventually levels off and becomes negative as international diversification increases. Product diversification moder...

2,706 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined how plant-level wages, occupational mix, workforce education and productivity vary with the adoption and use of new factory automation technologies such as programmable controllers, computer-automated design, and numerically controlled machines.
Abstract: This paper documents how plant-level wages, occupational mix, workforce education, and productivity vary with the adoption and use of new factory automation technologies such as programmable controllers, computer-automated design, and numerically controlled machines. Our cross-sectional results show that plants that use a large number of new technologies employ more educated workers, employ relatively more managers, professionals, and precision-craft workers, and pay higher wages. However, our longitudinal analysis shows little correlation between skill upgrading and the adoption of new technologies. It appears that plants that adopt new factory automation technologies have more skilled workforces both pre- and postadoption.

927 citations


Journal ArticleDOI
TL;DR: After considering other recognized risk factors including co‐infections, pregnant women infected with T. vaginalis at mid‐gestation were statistically significantly more likely to have a low birth weight infant, to deliver preterm, and to have an preterm low birth Weight infant.
Abstract: Background:Several studies have suggested that pregnant women infected withTrichomonas vaginalismay be at increased risk of an adverse outcome.Goal:To evaluate prospectively the association betweenT. vaginalisand risk of adverse pregnancy outcome in a large cohort of ethnically diverse women.Study D

805 citations


Journal ArticleDOI
24 Sep 1997-JAMA
TL;DR: It is recommended that women with expectantly managed PPROM remote from term receive antibiotics to reduce infant morbidity, and among GBS-negative women, significant pregnancy prolongation was seen with antibiotics.
Abstract: Context. —Intrauterine infection is thought to be one cause of preterm premature rupture of the membranes (PPROM). Antibiotic therapy has been shown to prolong pregnancy, but the effect on infant morbidity has been inconsistent. Objective. —To determine if antibiotic treatment during expectant management of PPROM will reduce infant morbidity. Design. —Randomized, double-blind, placebo-controlled trial. Setting. —University hospitals of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Patients. —A total of 614 of 804 eligible gravidas with PPROM between 24 weeks' and 0 days' and 32 weeks' and 0 days' gestation who were considered candidates for pregnancy prolongation and had not received corticosteroids for fetal maturation or antibiotic treatment within 1 week of randomization. Intervention. —Interavenous ampicillin (2-g dose every 6 hours) and erythromycin (250-mg dose every 6 hours) for 48 hours followed by oral amoxicillin (250-mg dose every 8 hours) and erythromycin base (333-mg dose every 8 hours) for 5 days vs a matching placebo regimen. Group B streptococcus (GBS) carriers were identified and treated. Tocolysis and corticosteroids were prohibited after randomization. Main Outcome Measures. —The composite primary outcome included pregnancies complicated by at least one of the following: fetal or infant death, respiratory distress, severe intraventricular hemorrhage, stage 2 or 3 necrotizing enterocolitis, or sepsis within 72 hours of birth. These perinatal morbidities were also evaluated individually and pregnancy prolongation was assessed. Results. —In the total study population, the primary outcome (44.1% vs 52.9%;P=.04), respiratory distress (40.5% vs 48.7%;P=.04), and necrotizing enterocolitis (2.3% vs 5.8%;P=.03) were less frequent with antibiotics. In the GBS-negative cohort, the antibiotic group had less frequent primary outcome (44.5% vs 54.5%;P=.03), respiratory distress (40.8% vs 50.6%;P=.03), overall sepsis (8.4% vs 15.6%;P=.01), pneumonia (2.9% vs 7.0%;P=.04), and other morbidities. Among GBS-negative women, significant pregnancy prolongation was seen with antibiotics (P Conclusions. —We recommend that women with expectantly managed PPROM remote from term receive antibiotics to reduce infant morbidity.

488 citations


Journal ArticleDOI
18 Sep 1997-Nature
TL;DR: It is shown that individual amino-acid enantiomers from Murchison are enriched in 15N relative to their terrestrial counterparts, so confirming an extraterrestrial source for an L-enantiomer excess in the Solar System that may predate the origin of life on the Earth.
Abstract: Many amino acids contain an asymmetric centre, occurring as laevorotatory, L, or dextrorotatory, D, compounds. It is generally assumed that abiotic synthesis of amino acids on the early Earth resulted in racemic mixtures (L- and D-enantiomers in equal abundance). But the origin of life required, owing to conformational constraints, the almost exclusive selection of either L- or D-enantiomers, and the question of why living systems on the Earth consist of L-enantiomers rather than D-enantiomers is unresolved. A substantial fraction of the organic compounds on the early Earth may have been derived from comet and meteorite impacts. It has been reported previously that amino acids in the Murchison meteorite exhibit an excess of L-enantiomers, raising the possibility that a similar excess was present in the initial inventory of organic compounds on the Earth. The stable carbon isotope compositions of individual amino acids in Murchison support an extraterrestrial origin -- rather than a terrestrial overprint of biological amino acids-although reservations have persisted. Here we show that individual amino-acid enantiomers from Murchison are enriched in 15N relative to their terrestrial counterparts, so confirming an extraterrestrial source for an L-enantiomer excess in the Solar System that may predate the origin of life on the Earth.

464 citations


Journal ArticleDOI
TL;DR: The link between organizational configurations and performance has become a central and somewhat controversial focus of research in the strategic management literature as discussed by the authors, and statistically aggregated studies have shown that organizational configurations are correlated with performance.
Abstract: The link between organizational configurations and performance has become a central and somewhat controversial focus of research in the strategic management literature. We statistically aggregated ...

353 citations


Journal ArticleDOI
TL;DR: An explicit cloud prediction model has been developed and incorporated into the Eta Model at the National Centers for Environmental Prediction as mentioned in this paper, where only one predictive variable, cloud mixing ratio, is added to the model's prognostic equations to represent both cloud liquid water and cloud ice.
Abstract: An explicit cloud prediction model has been developed and incorporated into the Eta Model at the National Centers for Environmental Prediction. In this scheme, only one predictive variable, cloud mixing ratio, is added to the model’s prognostic equations to represent both cloud liquid water and cloud ice. Precipitation is diagnostically calculated from cloud mixing ratio. Extensive tests have been performed. The statistical results show a significant improvement in the model precipitation forecasts. Diagnostic studies suggest that the inclusion of cloud ice is important in transferring water vapor to precipitation and in the enhancement of latent heat release; the latter subsequently affects the vertical motion field significantly.

321 citations


Journal ArticleDOI
TL;DR: Findings indicate that the treatment has triggered a specific humoral immune response in the tumor-bearing rats, and this is a novel minimally invasive cancer treatment combining the laser photophysical effects with the photobiological effects.

280 citations


Journal ArticleDOI
TL;DR: In this article, the amplitude variation with offset of carbon dioxide and brine-saturated background rocks was found to show increasing or decreasing amplitude variation in the AVO anomalies with offset.
Abstract: Hydrocarbon related “AVO anomalies” may show increasing or decreasing amplitude variation with offset. Conversely, brine‐saturated “background” rocks may show increasing or decreasing AVO.

278 citations



Journal ArticleDOI
TL;DR: An imaging protocol is outlined for evaluating patients with a wide variety of temporomandibular joint related signs and symptoms.
Abstract: Various imaging techniques for the temporomandibular joint are discussed with respect to uses, strengths, and limitations. An imaging protocol is outlined for evaluating patients with a wide variety of temporomandibular joint related signs and symptoms.

Journal ArticleDOI
TL;DR: The parallel implementation of the generalized stellar atmosphere and non-LTE (NLTE) radiative transfer computer program PHOENIX is described and the parallel algorithms developed for radiativeTransfer, spectral line opacity, and NLTE opacity and rate calculations are discussed.
Abstract: We describe the parallel implementation of our generalized stellar atmosphere and non-LTE (NLTE) radiative transfer computer program PHOENIX. We discuss the parallel algorithms we have developed for radiative transfer, spectral line opacity, and NLTE opacity and rate calculations. Our implementation uses a multiple instruction-multiple data design based on a relatively small number of MPI library calls. We report the results of test calculations on a number of different parallel computers and discuss the results of scalability tests.

Journal ArticleDOI
06 Mar 1997-Nature
TL;DR: In this article, the authors present evidence for the presence of spatially discrete microbial communities in Cretaceous rocks and advance a mechanism for the long-term survival of these subterranean communities.
Abstract: Deep subsurface microbial communities1 are believed to be supported by organic matter that was either deposited with the formation sediments or which migrated from the surface along groundwater flowpaths. Investigation has therefore focused on the existence of microorganisms in recently deposited or highly permeable sediments2,3. Fewer reports have focused on consolidated rocks4–7. These findings have often been limited by inadequate tracer methodology or non-sterile sampling techniques. Here we present evidence for the presence of spatially discrete microbial communities in Cretaceous rocks and advance a mechanism for the long-term survival of these subterranean communities. Samples were collected using aseptic methods and sensitive tracers8. Our results indicate that the main energy source for these communities is organic material trapped within shales. Microbial activity in shales appears to be greatly reduced, presumably because of their restrictive pore size9. However, organic material or its fermentation products could diffuse into adjacent, more permeable sandstones, where microbial activity was much more abundant. This process resulted in the presence of microbial communities at sandstone–shale interfaces. These microorganisms presumably ferment organic matter and carry out sulphate reduction and acetogenesis.

Journal ArticleDOI
TL;DR: Doppler on Wheels (DOW) as discussed by the authors is a portable, pencil-beam, pulsed, Doppler, 3-cm wavelength radar that has been used to study a wide variety of meteorological phenomena including tornadoes, severe storms and boundary layer processes.
Abstract: A portable, pencil-beam, pulsed, Doppler, 3-cm wavelength radar has been constructed to study a wide variety of meteorological phenomena including tornadoes, severe storms, and boundary layer processes. The new radar, the Doppler on Wheels (DOW), has full scanning capability, a real-time display and archiving, and is mounted on a truck for easy portability and full mobility. This portability allows the radar to be brought to within a kilometer of rare meteorological phenomena. At this range, the pencil beam of the radar is very narrow, permitting significantly higher-resolution measurements (at 3-km range, 64 m × 64 m × 75 m) than are usually possible with stationary or airborne systems. The radar employs a new high-powered, PC-based, digital intermediate frequency (IF) data acquisition scheme called the PIRAQ. The radar has successfully collected data in several tornadoes and tornadic storms and has been used to detect dust devils and other boundary layer structures. The sensitivity and mobility...

Journal ArticleDOI
TL;DR: In this article, positively charged polydiallyldimethylammonium chloride, P, was found to bind strongly to the surface of anionic montmorrillonite, M, platelets in aqueous dispersions up to a saturation (estimated to correspond to the binding of five P to one 1.0 nm × 200 nm M platelet).
Abstract: Positively charged polydiallyldimethylammonium chloride, P, was found to bind strongly to the surface of anionic montmorrillonite, M, platelets in aqueous dispersions up to a saturation (estimated to correspond to the binding of five P to one 1.0 nm × 200 nm M platelet) beyond which reversible physisorption occurred. Immersion of a substrate (glass, quartz, silica-wafer, gold, silver, and even Teflon) into an aqueous 1% solution of P and rinsing with ultrapure water for 10 min resulted in the strong adsorption of a 1.6 nm thick P on the substrate. Immersion of the P coated substrate into an aqueous dispersion of M and rinsing with ultrapure water for 10 min led to the adsorption of 2.5 nm thick M. Repeating the self-assembly steps of P and M for n number of times produced (P/M)n self-assembled films. Thickness of the M layer was found to depend on the external voltage applied during its self-assembly: applying a positive potential during the self-assembly of M increased the thickness of the M layer; appl...

Journal ArticleDOI
TL;DR: In this article, the authors presented detailed non-LTE synthetic spectra of hydrodynamic supernovae (SNe Ia) models and calculated both Chandrasekhar-mass deflagration models and sub-Chandrasekchar detonators.
Abstract: We present detailed non-LTE synthetic spectra of hydrodynamic supernovae (SNe) Ia models. We make no assumptions about the form of the spectrum at the inner boundary. We calculate both Chandrasekhar-mass deflagration models and sub-Chandrasekhar {open_quotes}helium detonators.{close_quotes} Gamma-ray deposition is handled in a simple, accurate manner. We have parameterized the storage of energy, which arises from the time-dependent deposition of radioactive decay energy, in a reasonable manner that spans the expected range. We find that the Chandrasekhar-mass deflagration model W7 of Nomoto, Thielemann, & Yokoi shows good agreement with the observed spectra of SN 1992A and SN 1994D, particularly in the UV, where our models are expected to be most accurate. The sub-Chandrasekhar models do not reproduce the UV deficit observed in normal SNe Ia. They do bear some resemblance to subluminous SNe Ia, but the shapes of the spectra (i.e., the colors) are opposite that of the observed ones, and the intermediate-mass element lines (such as SiII and CaII) are extremely weak, which seems to be a generic difficulty of the models. Although the sub-Chandrasekhar models have a significant helium abundance (unlike Chandrasekhar-mass models), helium lines are not prominent in the spectra near maximum light and thus do not actmore » as a spectral signature for the progenitor. {copyright} {ital 1997} {ital The American Astronomical Society}« less


Journal ArticleDOI
TL;DR: Despite the extensive literature on representative bureaucracy, only a few studies have examined empirically whether bureaucracies with different levels of representativeness produce different poli... as discussed by the authors, 2013.
Abstract: Despite the extensive literature on representative bureaucracy, only a few studies have examined empirically whether bureaucracies with different levels of representativeness produce different poli...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the evolution of non-homogeneous deformation in loose masonry sand and found that temporary modes of strain localization, observed during macroscopically uniform deformations of a specimen, gave way to a single, persistent shear band.
Abstract: Experimental results are presented which characterize the behaviour of a loose, fine-grained, water-saturated sand tested under globally undrained and drained conditions in a plane strain apparatus. The objective of this investigation is to provide insight into the phenomenon of shear banding in loose sand. Together with local measurements of boundary forces and deformations, stereophotogrammetry is used to investigate the progression of strain localization in plane strain compression. Typical results and findings concerning the evolution of non-homogeneous deformation are presented in detail. Shear banding occurred in both undrained and drained experiments on loose masonry sand. In general, temporary modes of strain localization, observed during macroscopically ‘uniform’ deformations of a specimen, gave way to a single, persistent shear band. A clear pattern of onset of the formation of the persistent shear band, mobilization of the maximum effective friction and complete formation of the band was observ...

Journal ArticleDOI
TL;DR: In this article, 24 shale and sandstone cores were collected from a site in northwestern New Mexico to investigate the distribution of microbial biomass and activities to gain insights into the physical controls on microbial activity and potential long-term survival in the subsurface.
Abstract: To investigate the distribution of microbial biomass and activities to gain insights into the physical controls on microbial activity and potential long‐term survival in the subsurface, 24 shale and sandstone cores were collected from a site in northwestern New Mexico. Bacterial biomass in the core samples ranged from below detection to 31.9 pmol total phospholipid fatty acid (PLFA) g‐1 of rock with no apparent relationship between lithology and PLFA abundance. No metabolic activities, as determined by anaerobic mineralization of [14C]acetate and [14C]glucose and 35SO4 2‐ reduction, were detected in core samples with pore throats <0.2 fan in diameter, smaller than the size of known bacteria. However, enrichments revealed the presence of sulfate‐re‐ducing bacteria, and 35SO4 2‐ reduction was detected upon extended (14 days) incubation in some small‐pore‐throat samples. In contrast, relatively rapid rates of metabolic activity were more common in core samples containing a significant fraction of pore throat...

Journal ArticleDOI
01 Oct 1997-Ecology
TL;DR: Findings demonstrate that factors that caused anole species to converge repeatedly in the West Indies are not present in mainland regions, and that environmental factors can strongly influence the shape of evolutionary radiations.
Abstract: Comparisons between closely related radiations in different environments provide a unique window into understanding how abiotic and biotic factors shape evolu- tionary pathways. Anolis lizards have radiated extensively in the West Indies, as well as mainland Central and South America. In the Caribbean, similar communities of anole species specialized for different habitats (ecomorphs) have evolved independently on each Greater Antillean island. We examined ecological and morphological data on 49 Anolis species (33 Caribbean, 16 mainland) to investigate whether the same set of ecomorphs has arisen in mainland regions. More generally, we investigated whether the relationship between ecology and morphology was similar among anoles in the two regions. Radiations in the two regions are very different. The majority of mainland anole species exhibit morphological characteristics unlike any Caribbean ecomorph. Furthermore, rela- tionships between ecology and morphology are very different between the two sets of anole species. Among mainland anole species, toepad size is positively correlated with perch height, whereas tail length is negatively related to perch diameter. In contrast, among Caribbean anole species, both forelimb length and body mass are positively associated with perch diameter, and both tail length and hindlimb length are negatively related to perch diameter. Biomechanical considerations provide a functional basis for some of these cor- relations, but much variation remains to be explained. These findings demonstrate that factors that caused anole species to converge repeatedly in the West Indies are not present in mainland regions, and that environmental factors can strongly influence the shape of evolutionary radiations.

Journal ArticleDOI
TL;DR: In this article, the authors focus on a basic element in the adaptation process, i.e., flexibility within the strategic decision-making process, and derive hypotheses concerning the factors that lead to flexibility (versus rigidity) from both information processing and ideological perspectives.
Abstract: Adaptation is a crucial challenge for organizations, and an important theme in the strategy and organization theory literature. We still have much to learn, however, about the strategic processes by which adaptation is achieved. In this paper we focus on a basic element in the adaptation process, i.e. flexibility within the strategic decision-making process. We concentrate on strategic decisions because these choices are the most important adaptations the firm makes. We suggest that the core of all organizational adaptation is a decision-making process. Unless the decision-making process itself is flexible, it is unlikely the organization can be flexible enough to adapt. We derive hypotheses concerning the factors that lead to flexibility (versus rigidity) from both information processing and ideological perspectives, and test them in a study involving 57 strategic decisions in 25 companies. Our results identify three contextual factors related to both perspectives -- including competitive threat, slack and uncertainty -- that are helpful in understanding flexibility in strategy decision making. While managers appear to be more flexible when decisions are uncertain, we found that in the very conditions where managers need the most flexibility (high competitive threat and low slack), they are least likely to be flexible.

Journal ArticleDOI
TL;DR: In this article, the results of a survey of husbands and wives in expatriate dual-career couples are analyzed relative to differences between the expatriates and their trailing spouses.
Abstract: Dual-career expatriate couples present a challenging set of problems for international human resource managers. The results of a survey of husbands and wives in expatriate dual-career couples are analyzed relative to: 1) differences between the expatriates and their trailing spouses; 2) differences between male- and female-led dual-career couples; 3) differences between dual-career couples' opinions prior to expatriation and upon repatriation. The results of the study indicate dual-career couples have relatively consistent concerns and expectations prior to expatriation and upon repatriation to their home country. The significant differences observed were between male-led dual-career couples prior to expatriation when compared to male-led dual-career couples upon repatriation. In addition, the dual-career expatriate respondents did not feel the MNC that transferred them overseas provided adequate training or social support during the international assignment.

Journal ArticleDOI
TL;DR: Under conditions where nitric oxide and superoxide are produced simultaneously, oxidation of dichlorofluorescin may be mediated by the formation of peroxynitrite, a potent oxidant which may be an important mediator of cellular injury.
Abstract: The simultaneous production of nitric oxide and superoxide anion leads to the formation of peroxynitrite, a potent oxidant which may be an important mediator of cellular injury. Oxidation of dichlorofluorescin to the fluorescent dichlorofluorescein has been used as a marker for cellular oxidant production. The mechanisms of peroxynitrite-mediated oxidation of dichlorofluorescin to dichlorofluorescein were investigated. Chemically synthesized peroxynitrite (50–500 nM) induced the oxidation of dichlorofluorescin to dichlorofluorescein in a linear fashion. In addition, the simultaneous generation of nitric oxide and superoxide anion induced the oxidation of dichlorofluorescin to dichlorofluorescein, while nitric oxide (1–10 μM) alone under aerobic conditions did not. Peroxynitrite-mediated oxidation of dichlorofluorescin was not inhibited by the hydroxyl radical scavengers mannitol (100 mM) or dimethylsulfoxide (100 mM). Moreover, peroxynitrite-mediated oxidation of dichlorofluorescin was not dependent upon ...


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the relationship between unemployment duration and the spatial distribution of employment and found that individuals with more access to employment are found to have shorter unemployment spells and that the effect of access on unemployment duration is sensitive to the specification of access.

Journal ArticleDOI
TL;DR: In this paper, the authors presented new reconstructions for the northern Lake Tanganyika subbasins, based on reflection seismic, core and outcrop data, using a chronological model for these reconstructions, against which yet to be obtained age dates based on core samples can be compared.
Abstract: Palaeogeographic and lake-level reconstructions provide powerful tools for evaluating competing scenarios of biotic, climatic and geological evolution within a lake basin. Here we present new reconstructions for the northern Lake Tanganyika subbasins, based on reflection seismic, core and outcrop data. Reflection seismic radiocarbon method (RSRM) age estimates provide a chronological model for these reconstructions, against which yet to be obtained age dates based on core samples can be compared. A complex history of hydrological connections and changes in shoreline configuration in northern Lake Tanganyika has resulted from a combination of volcanic doming, border fault evolution and climatically induced lake-level fluctuations. The stratigraphic expression of lake-level highstands and lowstands in Lake Tanganyika is predictable and cyclic (referred to here as Capart Cycles), but in a pattern that diers profoundly from the classic Van Houten cycles of some Newark Supergroup rift basins. This dierence results from the extraordinary topographic relief of the Western Rift lakes, coupled with the rapidity of large-scale lake-level fluctuations. Major unconformity surfaces associated with Lake Tanganyika lowstands may have corresponded with high-latitude glacial maxima throughout much of the mid- to late Pleistocene. Rocky shorelines along the eastern side of the present-day Ubwari Peninsula (Zaire) appear to have had a much more continuous existence as littoral rock habitats than similar areas along the north-western coastline of the lake (adjacent to the Uvira Border Fault System), which in turn are older than the rocky shorelines of the north-east coast of Burundi. This model of palaeogeographic history will be of great help to biologists trying to clarify the evolution of endemic invertebrates and fish in the northern basin of Lake Tanganyika.

Journal ArticleDOI
TL;DR: Oral melanomas occur in adults almost three times more frequently in men than women and have a decided predilection for the palate and gingiva, and guidelines for reporting oral melanomas are suggested.
Abstract: A workshop to discuss primary oral melanomas was convened at the annual Western Society of Teachers of Oral Pathology meeting in Bannf, Alberta, Canada. Fifty oral melanomas, identified from the files of the participants, were reviewed in order to better understand the clinical features, histologic spectrum, and natural history of these perplexing lesions. Results confirmed that oral melanomas occur in adults almost three times more frequently in men than women and have a decided predilection for the palate and gingiva. Some lesions exhibit a clinically detectable and prolonged in situ growth phase, whereas others seem to lack this property and exhibit only or predominantly invasive characteristics. Recurrences, metastases, and death from tumor were characteristic of the follow-up of a limited number of patients. Until definitive prospective data are collected that elucidate natural history, oral mucosal melanomas should be tracked separately from cutaneous lesions. All oral pigmented lesions that are not clinically diagnostic should be biopsied. Lesions with equivocal histopathologic features might be referred to as "atypical melanocytic proliferation" and should be excised. Recognition of lesions in an early in situ phase and aggressive treatment should have a favorable effect on prognosis. To enhance future or prospective study of these rare neoplasms, guidelines for reporting oral melanomas are suggested.

Journal ArticleDOI
TL;DR: A cautious approach is supported in returning patients to early full activity, including sports, after anterior cruciate ligament reconstruction with a semitendinosus autograft.
Abstract: The purpose of this study was to evaluate the histologic and biomechanical changes that occur between 12 and 52 weeks in an intraarticular, semitendinosus autograft placed through tibial and femoral drill holes in a rabbit model. The results of this study show that, in this rabbit model, the soft tissue graft maintained its biologic fixation in the osseous tunnel when stressed to failure at 1 year. The bony fixation occurred by the formation of an indirect tendon insertion, and this formation was complete by 26 weeks. At 52 weeks, large differences persisted in the strength and stiffness of the graft compared with the normal semitendinosus tendon and anterior cruciate ligament. Based on the results of this study, we support a cautious approach in returning patients to early full activity, including sports, after anterior cruciate ligament reconstruction with a semitendinosus autograft.

Journal ArticleDOI
TL;DR: In this article, the use of gas chromatography/isotope ratio mass spectrometry (GC/IRMS) as a complimentary correlation technique to GC and GC/MS, particularly for samples that have undergone extensive weathering, was investigated.
Abstract: Correlation of crude oils and refined hydrocarbon products spilled in the environment with their respective sources is commonly undertaken using techniques such as gas chro matography (GC) or gas chromatography/mass spectrometry (GC/MS) or bulk parameters such as the isotopic composition of the aliphatic or aromatic fractions. Under certain circumstances extensive weathering of the samples, through evaporation, water-washing, or biodegradation, may make such correlations extremely difficult and the results somewhat tenuous. Results are presented in this paper from an investigation to study the use of gas chromatography/isotope ratio mass spectrometry (GC/IRMS) as a complimentary correlation technique to GC and GC/MS, particularly for samples that have undergone extensive weathering. In the study, a variety of oils and refined hydrocarbon products, weathered both artificially and naturally, were analyzed by GC, GC/MS and GC/IRMS. In cases where samples have lost their more volatile n-alkanes as a result of...