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In this work, we report the independent discovery and analysis of nine new compact triply eclipsing triple star systems found with the Transiting Exoplanet Survey Satellite (TESS) mission: TICs 47151245, 81525800, 99013269, 229785001, 276162169, 280883908, 294803663, 332521671, and 356324779. Each of these nine systems exhibits distinct third-body eclipses where the third (‘tertiary’) star occults the inner eclipsing binary (EB), or vice versa. We utilize a photodynamical analysis of the TESS photometry, archival photometric data, TESS eclipse timing variations of the EBs, available archival spectral energy distribution (SED) curves, and, in some cases, newly acquired radial velocity observations, to solve for the parameters of all three stars, as well as most of the orbital elements. From these analyses we find that the outer orbits of all nine systems are viewed nearly edge on (i.e. within ≲4°), and six of the systems are coplanar to within 5°; the others have mutual inclination angles of 20°, 41°, and possibly 179° (i.e. a retrograde outer orbit). The outer orbital periods range from 47.8 to 604 d, with eccentricities spanning 0.004–0.61. The masses of all 18 EB stars are in the range of 0.9–2.6 M⊙ and are mostly situated near the main sequence. By contrast, the masses and radii of the tertiary stars range from 1.4 to 2.8 M⊙ and 1.5 to 13 R⊙, respectively. We make use of the system parameters from these nine systems, plus those from a comparable number of compact triply eclipsing triples published previously, to gain some statistical insight into their properties.

We report the discovery with $TESS$ of a third set of eclipses from V994 Herculis (TIC 424508303), previously only known as a doubly-eclipsing system. The key implication of this discovery and our analyses is that V994 Her is the second fully-characterized (2+2) + 2 sextuple system, in which all three binaries eclipse. In this work, we use a combination of ground-based observations and $TESS$ data to analyze the eclipses of binaries A and B in order to update the parameters of the inner quadruple's orbit (with a derived period of 1062 $\pm$ 2d). The eclipses of binary C that were detected in the $TESS$ data were also found in older ground-based observations, as well as in more recently obtained observations. The eclipse timing variations of all three pairs were studied in order to detect the mutual perturbations of their constituent stars, as well as those of the inner pairs in the (2+2) core. At the longest periods they arise from apsidal motion, which may help constraining parameters of the component stars' internal structure. We also discuss the relative proximity of the periods of binaries A and B to a 3:2 mean motion resonance. This work represents a step forward in the development of techniques to better understand and characterize multiple star systems, especially those with multiple eclipsing components., Comment: Accepted for publication by MNRAS

We report the results of the photodynamical analyses of four compact, tight triple stellar systems, KICs 6964043, 5653126, 5731312, 8023317, based largely on $Kepler$ and $TESS$ data. All systems display remarkable eclipse timing and eclipse depth variations, the latter implying a non-aligned outer orbit. Moreover, KIC 6964043 is also a triply eclipsing system. We combined photometry, ETV curves, and archival spectral energy distribution data to obtain the astrophysical parameters of the constituent stars and the orbital elements with substantial precision. KICs 6964043 and 5653126 were found to be nearly flat with mutual inclinations $i_{mut}=4.1$ deg and $12.3$ deg, respectively, while KICs 5731312, 8023317 ($i_{mut}=39.4$ deg and $55.7$ deg, respectively) are found to lie in the high $i_{mut}$ regime of the von Zeipel-Kozai-Lidov (ZKL) theorem. We show that currently both high inclination triples exhibit observable unusual retrograde apsidal motion. Moreover, the eclipses will disappear in all but one of the four systems within a few decades. Short-term numerical integrations of the dynamical evolution reveal that both high inclination triples are currently subject to ongoing, large amplitude ($\Delta e\sim0.3$) inner eccentricity variations on centuries-long timescales, in accord with the ZKL theorem. Longer-term integrations predict that two of the four systems may become dynamically unstable on $\sim$ Gyr timescales, while in the other two triples common envelope phases and stellar mergers may occur. Finally we investigate the dynamical properties of a sample of 71 KIC/TIC triples statistically, and find that the mutual inclinations and outer mass ratios are anti-correlated at the 4$\sigma$ level. We discuss the implications for the formation mechanisms of compact triples., Comment: Accepted for publication in MNRAS. This arXiv version contains the full, long LaTeX tables of the times of minima data, which will be available as machine readable online supplementary material in the journal version

In this work we report the discovery and analysis of six new compact triply eclipsing triple star systems found with the TESS mission: TICs 37743815, 42565581, 54060695, 178010808, 242132789, and 456194776. All of these exhibit distinct third body eclipses where the inner eclipsing binary (EB) occults the third (`tertiary') star, or vice versa. We utilized the TESS photometry, archival photometric data, and available archival spectral energy distribution curves (SED) to solve for the properties of all three stars, as well as many of the orbital elements. We describe in detail our SED fits, search of the archival data for the outer orbital period, and the final global photodynamical analyses. From these analyses we find that all six systems are coplanar to within $0^\circ$ - $5^\circ$, and are viewed nearly edge on (i.e., within a couple of degrees). The outer orbital periods and eccentricities of the six systems are {$P_{\rm out}$ (days), $e$}: {68.7, 0.36}, {123, 0.16}, {60.7, 0.01}, {69.0, 0.29}, {41.5, 0.01}, {93.9, 0.29}, respectively, in the order the sources are listed above. The masses of all 12 EB stars were in the range of 0.7-1.8 M$_\odot$ and were situated near the main sequence. By contrast, the masses and radii of the tertiary stars ranged from 1.5-2.3 M$_\odot$ and 2.9-12 R$_\odot$, respectively. We use this information to estimate the occurrence rate of compact flat triple systems., Comment: 28 pages, 7 figures, 16 tables; accepted for publication in MNRAS

Aims. We introduce a novel way to identify new compact hierarchical triple stars by exploiting the huge potential of Gaia DR3 and also its future data releases. We aim to increase the current number of compact hierarchical triple systems significantly. Methods. We used several eclipsing binary catalogs from different sky surveys that list a total of more than 1 million targets to search for Gaia DR3 non-single-star orbital solutions with periods substantially longer than the eclipsing periods of the binaries. Those solutions in most cases are likely to belong to outer orbits of tertiary stars in those systems. We also attempted to validate some of our best-suited candidates using TESS eclipse timing variations. Results. We find 403 objects with suitable Gaia orbital solutions of which 27 are already known triple systems, leaving 376 newly identified hierarchical triple system candidates in our sample. We find the cumulative probability distribution of the outer orbit eccentricities to be very similar to those found in earlier studies based on observations of the Kepler and OGLE missions. We find measurable nonlinear eclipse timing variations or third-body eclipses in the TESS data for 192 objects which we also consider to be confirmed candidates. Of these, we construct analytical light-travel time effect models for the eclipse timing variations of 22 objects with wellsampled TESS observations. We compare the outer orbital parameters from our solutions with those from the Gaia solutions and find that the most reliable orbital parameter is the orbital period, while the values of the other parameters should be used with caution.

We present an analysis of a newly discovered 2+1 + 1 quadruple system with TESS containing an unresolved eclipsing binary (EB) as part of TIC 121088960 and a close neighbour TIC 121088959. The EB consists of two very low-mass M dwarfs in a highly eccentric (e = 0.709) short-period (P = 3.043 58 d) orbit. Given the large pixel size of TESS and the small separation (3${_{.}^{\prime\prime}}$9) between TIC 121088959 and TIC 121088960 we used light centroid analysis of the difference image between in-eclipse and out-of-eclipse data to show that the EB likely resides in TIC 121088960, but contributes only ∼10 per cent of its light. Radial velocity data were acquired with iSHELL at NASA’s Infrared Facility and the Coudé spectrograph at the McDonald 2.7-m telescope. For both images, the measured RVs showed no variation over the 11 d observational baseline, and the RV difference between the two images was 8 ± 0.3 km s−1. The similar distances and proper motions of the two images indicate that TIC 121088959 and TIC 121088960 are a gravitationally bound pair. Gaia’s large RUWE and astrometric_excess_noise parameters for TIC 121088960, further indicate that this image is the likely host of the unresolved EB and is itself a triple star. We carried out an SED analysis and calculated stellar masses for the four stars, all of which are in the M dwarf regime: 0.19 M⊙ and 0.14 M⊙ for the EB stars and 0.43 M⊙ and 0.39 M⊙ for the brighter visible stars, respectively. Lastly, numerical simulations show that the orbital period of the inner triple is likely the range 1–50 yr.

In this work we report the discovery and analysis of three new triply eclipsing triple star systems found with the TESS mission during its observations of the northern skies: TICs 193993801, 388459317, and 52041148. We utilized the TESS precision photometry of the binary eclipses and third-body eclipsing events, ground-based archival and follow-up photometric data, eclipse timing variations, archival spectral energy distributions, as well as theoretical evolution tracks in a joint photodynamical analysis to deduce the system masses and orbital parameters of both the inner and outer orbits. In one case (TIC 193993801) we also obtained radial velocity measurements of all three stars. This enabled us to `calibrate' our analysis approach with and without `truth' (i.e., RV) data. We find that the masses are good to 1-3% accuracy with RV data and 3-10% without the use of RV data. In all three systems we were able to find the outer orbital period before doing any detailed analysis by searching for a longer-term periodicity in the ASAS-SN archival photometry data -- just a few thousand ASAS-SN points enabled us to find the outer periods of 49.28 d, 89.86 d, and 177.0 d, respectively. From our full photodynamical analysis we find that all three systems are coplanar to within $1^\circ - 3^\circ$. The outer eccentricities of the three systems are 0.003, 0.10, and 0.62, respectively (i.e., spanning a factor of 200). The masses of the three stars {Aa, Ab, and B} in the three systems are: {1.31, 1.19, 1.34}, {1.82, 1.73, 2.19}, and {1.62, 1.48, 2.74} M$_\odot$, respectively., Accepted for publication in MNRAS. Tables 2-4, which will be published electronic only in the journal version, are fully available in this arXiv version

Tidally forced apsidal motion in eccentric eclipsing binaries is a key observable of stellar structure studies, and may serve as important probe for different tidal dissipation theories. There are, however, alternative physical processes which result in additional contributions to the observed apsidal motion. Here we mainly concentrate on the perturbing effect of a third, distant stellar companion, forming a hierarchical triple system with the eclipsing pair. First we discuss the mathematical form of the combined third body and tidally forced apsidal motions, and its observational aspects. Then we present a brief description of an eclipse timing variation study (based on the above mentioned analytical formulae) of 26 Kepler spacecraft-discovered 3-rd body perturbation-dominated compact hierarchical triples.

Every smooth closed curve can be represented by a suitable Fourier sum. We show that the ensemble of curves generated by randomly chosen Fourier coefficients with amplitudes inversely proportional to spatial frequency (with a smooth exponential cutoff), can be accurately mapped on the physical ensemble of worm-like polymer loops. We find that measures of correlation on the scale of the entire loop yield a larger persistence length than that calculated from the tangent-tangent correlation function at small length scales. The conjecture that physical loops exhibit additional rigidity on scales comparable to the entire loop due to the contribution of twist rigidity, can be tested experimentally by determining the persistence length from the local curvature and comparing it with that obtained by measuring the radius of gyration of dsDNA plasmids. The topological properties of the ensemble randomly generated worm-like loops are shown to be similar to that of other polymer models., Comment: 4 pages, 3 figures; paper had been substantially re-written, new results added

The use of real time channel borrowing in digital cellular asynchronous hybrid FDMA/TDMA systems is considered. These systems, which are exemplified by North American digital cellular (IS-54), are asynchronous in the sense that time slots in different cells are not aligned. CBWL (channel borrowing without locking) techniques can be applied but (without cell-to-cell synchronization) borrowing individual time slots from adjacent cells would violate co-channel interference constraints. Instead, frequency carriers can be borrowed. In IS-54, a carrier supports three TDMA slots. So if only one TDMA slot is needed in the borrowing cell, two TDMA slots are unnecessarily transferred. We devised an appropriate carrier borrowing scheme and an analytical model to determine the traffic performance of TDMA/CBWL. Fast carrier returning is used to increase channel utilization by returning borrowed carriers as soon as possible. An efficient computational method that uses macro-states, decomposition, combinatorial analysis and the convolution algorithm is devised to find blocking probabilities. The results show that in comparison with FCA, the new CBWL scheme can significantly improve system performance of asynchronous TDMA cellular systems that use FDMA/TDMA multiplexing.

The EXCEDE III sounding rocket flight of April 27, 1990 used a ∼18 Ampere ∼2.5 keV electron beam to produce an artificial aurora in the region ∼90 to ∼115 km. A “daughter” sensor payload remotely monitored the low-energy X-ray spectrum while scanning photometers measured the spatial profile of prompt emissions of N2+ (1N) and N2 (2P) transitions (3914A and 3805A, respectively). Two Ebert-Fastie spectrometers measured the spectral region from 1800 to 8000A. On the “mother” accelerator payload, the return current electron differential energy spectra were monitored by an electrostatic analyzer (up to 10 keV) and by a retarding potential analyzer (0 eV to 100 eV). We present an overview of the results from this experiment.

A series of lidar experiments has been conducted using the Atmospheric Balloonborne Lidar Experiment payload, ABLE. These experiments included the measurement of atmospheric Rayleigh and Mie backscatter from near space (∼ 30 km) and Raman backscatter measurements of atmospheric constituents as a function of altitude. The ABLE payload consisted of a frequency-tripled Nd: YAG laser transmitter, a 50 cm receiver telescope, and filtered photodetectors in various focal plane configurations. The payload provided for lidar pointing, thermal control, data handling, and remote control of the lidar system. Comparison of ABLE performance with that of a space lidar shows significant performance advantages and cost effectiveness for balloonborne lidar systems.

The methods developed by Rappaport et al. [Ann. Occup. Hyg. 39 (1995) 469] and Lyles et al. [J. Agri. Bio. Environ. Stat. 2 (1997a) 64; Ann. Occup. Hyg. 41 (1997b) 63]) for assessing workplace exposures on a group-by-group basis are extended to allow for the simultaneous assessment of data from multiple worker groups within the same industry. These extended methods allow models to be fit simultaneously to data on all groups in a study, even when some of the groups might not contribute adequate information to be modeled separately. We assume that the exposures are log-normally distributed, and that they can be adequately modeled by a mixed effects regression model with parameters for exposure levels and for between- and within-worker variance components. Simultaneously analyzing data from multiple groups is only advantageous when at least one of these variance components can be assumed to be homogeneous across the groups. Here, we advocate testing an assumption of homogeneous within-worker variance components, sigma(2)(w,h), using a likelihood ratio test to choose between a full model (distinct sigma(2)(w,h) for each group) and a reduced model (common sigma(2)(w) across groups). We then develop a procedure, which is conditional on the results of the likelihood ratio test, for testing whether or not each group of workers is overexposed to the contaminant of interest. This modeling and testing procedure was applied to 39 different data sets, each containing data for multiple groups, from a wide variety of industries. For these data, the testing procedure generally resulted in the same conclusion regarding overexposure under both models, even in those data sets where the within-worker variance components appeared to be quite heterogeneous. We also conducted a small simulation study to estimate the significance level of the proposed testing procedure, and found that the significance levels tended to be adequately close to the specified nominal level when a likelihood ratio test with significance level of at least 0.01 was used as a preliminary test. Additionally, we make specific recommendations for designing studies and suggest a method for determining whether engineering and administrative controls or individual-level interventions would be of most benefit to an overexposed group of workers.

Hemoglobin (Hb) and albumin (Alb) adducts of the benzene metabolites benzene oxide (BO) and 1,4-benzoquinone (1,4-BQ) were analyzed by gas chromatography-mass spectrometry in 43 exposed workers and 44 unexposed controls from Shanghai, China, as part of a larger cross-sectional study of benzene biomarkers. When subjects were divided into controls (n = 44) and workers exposed to/=31 ppm (n = 21) and31 ppm (n = 22) of benzene, median 1,4-BQ-Alb adducts were 2110, 5850, and 13,800 pmol/g Alb, respectively (correlation with exposure: Spearman r = 0.762; P0.0001); median BO-Alb adducts were 106, 417, and 2400 pmol/g Alb, respectively (Spearman r = 0.877; P0.0001); and median BO-Hb adducts were 37.1, 50.5, and 136 pmol/g Hb, respectively (Spearman r = 0.757; P0.0001). To our knowledge, this is the first observation that adducts of 1,4-BQ are significantly correlated with benzene exposure. When compared on an individual basis, Alb adducts of 1,4-BQ and BO and Hb adducts of BO were highly correlated with each other and with urinary phenol and hydroquinone (P0.0001 for all of the comparisons). Although detectable in the assays, Hb adducts of 1,4-BQ and both Hb and Alb adducts of 1,2-BQ produced erratic results and are not reported. Interestingly, cigarette smoking increased Alb adducts of 1,4-BQ but not of BO, suggesting that benzene from cigarette smoke was not the primary contributor to the 1,4-BQ adducts.

Particulate exposures were assessed among construction workers engaged in hot processes in four jobs (boilermakers, ironworkers, pipefitters and welder-fitters) at nine sites in the U.S. After being trained by occupational hygienists, the workers obtained shift-long personal samples at each site for total particulates (TP). Selected samples were also assayed for manganese (Mn), nickel (Ni), and chromium (Cr). Workers provided information about process- and task-related covariates that were present on the days of monitoring. Data were investigated with mixed-model regression analyses that designated the jobs and covariates as fixed effects and the worker and error terms as random effects. Results indicated that the within-worker variance components, but not the between-worker variance components, could be pooled among jobs. Mean air levels for a given agent varied by roughly six to 100 fold among the jobs, with boilermakers and ironworkers experiencing much higher levels of TP and Mn than pipefitters and welder-fitters. Limited data also suggested that welder-fitters were exposed to greater levels of Ni and Cr than pipefitters. Sufficient sample sizes were available to evaluate the effects of covariates upon exposures to TP and Mn. As expected, processes involving more than 50% hot work led to substantially higher levels of TP and Mn than those involving shorter durations of hot work. Local-exhaust or mechanical ventilation reduced exposure to TP (but not Mn) by as much as 44%, and shielded or manual arc welding increased exposure to Mn (but not TP) by about 80%. Parameters estimated with these mixed models were used to calculate probabilities that workers were exposed at levels above U.S. occupational exposure limits (OELs). Regarding TP and Mn, these calculations suggested that 26-95% of exposures to boilermakers and pipefitters and 2-13% of exposures to pipefitters and welder-fitters exceeded the current Threshold Limit Values. Among welder-fitters, limited data also pointed to probabilities of 2-50% for exceeding particular OELs for Ni and Cr. Using the significance of the estimated random-worker effects as a gauge for the uniformity of exposure within a job, administrative or engineering changes appear appropriate for reducing exposures to boilermakers and ironworkers, while individual personal environments should be investigated for pipefitters and welder-fitters.

During the manufacturing of reinforced plastics, large amounts of styrene and trace quantities of styrene-7,8-oxide (SO) are released. Since previous work suggests that inhalation of even small amounts of SO might be an important health risk, we investigated several possible factors contributing to styrene and SO exposure during the manufacture of reinforced plastics. Factors related to job type, worker and the type and quantity of styrene-containing resins were investigated using mixed-effects multiple linear regression models. Overall, SO exposure levels were positively correlated with styrene exposure levels. However, this correlation was statistically significant only among hand laminators who had the highest exposures to both styrene and SO. An important factor for predicting both styrene and SO concentrations was the type of resin used, while the quantity of resin consumed was predictive of styrene but not of SO exposure. Since So exposure appears to be associated with factors other than coexposure to styrene, more effort should be placed on investigating emissions of SO per se. The type of mixed-models regression analysis employed in this study can be used for clarifying the underlying patterns for exposures to styrene and SO as well as for evaluating preventive measures.

Investigations of cancer and cytogenetic damage among reinforced-plastics workers have produced contradictory results. In all studies, the focus has been on styrene rather than the carcinogen, styrene-7,8-oxide (SO), traces of which are generated during the manufacturing process. Because styrene is present at very high levels and is metabolized almost exclusively through SO, coexposures to SO have been discounted. This study investigated the relative contributions of airborne styrene and SO and of smoking toward several SO-specific biomarkers (DNA and albumin adducts) and sister chromatid exchanges in the blood of 48 reinforced-plastics workers. Among individual subjects, albumin and DNA adducts as well as sister chromatid exchanges were significantly correlated with styrene exposure. However, among the 20 subjects with measurements to both styrene and SO, albumin adducts were significantly correlated with exposure to SO but not to styrene. Finally, among the 10 job groups, surprisingly strong correlations (0.709or = ror = 0.966) were found between all SO biomarkers and exposure to SO but not to styrene. Calculations suggest that SO was about 2000 times more effective than styrene in producing SO biomarkers. After accounting for the disparate exposures to the two chemicals, a typical worker received 71% of the systemic dose of SO via inhalation; nonetheless, 5 of the 20 subjects received the majority of the SO dose from styrene. Cigarette smoking increased levels of SO-albumin and SO-DNA adducts, suggesting that SO was a constituent of tobacco smoke. We conclude that inhalation of SO should be considered in any interventions to reduce health risks.

OBJECTIVE: To understand whether previous styrene exposure increases the human liver9s ability to convert styrene into styrene oxide. METHODS: The hypothesis was tested that the average linear metabolic rate constant kappa was the same in both exposed and unexposed groups, when the exposed group comprised people with a history of styrene exposure and the unexposed group had no exposure. In an experimental chamber, these two groups of subjects were exposed to a concentration of 80 ppm styrene for two hours. A three compartment pharmacokinetic model was used to define kappa. Based on large sample theory, the comparison of estimated mean values of kappa in the exposed and unexposed groups was shown to be equivalent to a comparison of the estimated mean values of the hepatic clearance X in the two groups. A method was developed to estimate X for each subject in both groups from the subject9s height, weight, and estimated asymptotic styrene decay constant alpha. Here, alpha was estimated individually from observed blood concentrations over time when sufficient time had elapsed after the controlled exposure. RESULTS: The proposed methodology of comparing the estimated mean values of kappa in exposed and unexposed groups reduced the number of specific physiological variables involved to three, all of which were estimable from data based on simple direct measurements. In contrast, other methods based on pharmacokinetic models usually involved many variables that were non-estimable on an individual basis. Consequently, statistical comparisons were impossible. These methods were applied to analyse previously published data on the time course of styrene concentrations in arterial blood of subjects in both exposed and unexposed groups. A Wilcoxon non-parametric rank sum test with the individually estimated X values was used, and no significant difference in the means of X in the two groups was found. CONCLUSION: The linear metabolic rate constant kappa for humans is probably not altered by previous exposure to styrene. This result is in agreement with some experimental studies on animals. However, in the data analysis, it was noted that the number of subjects in each group was small (6-7) and that the styrene concentration data did not exactly reflect true behaviour of asymptotic decay. Further studies are still needed to draw more definitive conclusions.

Hemoglobin and albumin adducts of the carcinogen styrene-7,8-oxide (SO) were measured in 48 workers exposed to both styrene and SO in a boat manufacturing plant. Personal exposures to both substances were measured repeatedly over the course of 1 year (styrene:0.9-235 mg/m3 with a mean of 64.3 mg/m3 for 48 subjects; S0: 13.4-525 mu g/m3 with a mean of 159 mu g/m3 for 20 subjects). Cysteine and carboxylic acid adducts of SO with hemoglobin and albumin were assayed on one or more occasions for each subject. The proteins were subjected to base hydrolysis to release styrene glycol, representing carboxylic acid-bound SO, and were then treated with Raney nickel to release 1-phenylethanol and 2-phenylethanol, representing cysteine-bound SO. These three analytes were extracted, derivatized, and analyzed by gas chromatography-mass spectrometry. No evidence was found of any exposure-related increase in hemoglobin adducts. In contrast, albumin adducts were found to increase with exposures to either styrene or SO, the latter apparently being more important. This suggests that exposure to low levels of SO in the air may be important among workers in the reinforced plastics industry. Significant levels of SO adducts of albumin and hemoglobin were also detected in proteins obtained from persons without occupational exposure to styrene or to SO. This finding opens the possibility that SO is either a dietary or an environmental contaminant or is produced endogenously.

Benzene is metabolized to a number of electrophilic species that are capable of binding to both DNA and proteins. We used adducts of hemoglobin (Hb) and bone marrow proteins to study the disposition of three benzene and metabolites (benzene oxide [BO], 1,2-benzoquinone [1,2-BQ], and 1,4-benzoquinone [1,4-BQ]) in F344 rats and B6C3F1 mice following a single oral dosage of [13C6]benzene and/or [14C]benzene. Our assays focused upon cysteine adducts that accounted for 38 to 45% of protein binding to Hb and 63 to 81% of protein binding to bone marrow. Although both mice and rats showed dose-related increases in Hb and bone marrow protein adducts of BO and of the two benzoquinones, large intertissue and interspecies differences were noted, suggesting different preferences in metabolic pathways. The highest levels of adducts in mice were of 1,4-BQ (10-27% of all cysteine adducts), while in rats, BO adducts predominated in Hb (73% of all cysteine adducts) and 1,2-BQ adducts predominated in the bone marrow (14% of all cysteine adducts). High background levels of 1,2-BQ and 1,4-BQ adducts were also detected in both species, indicating that the toxic effects of quinone metabolites may only be important at high levels of benzene exposure.

To facilitate the communication of ideas, orders and treatment plans among providers practicing in a multidisciplinary ambulatory care setting, we have created an event-directed messaging system integrated into our larger Ambulatory Care Information System (ACIS). ACIS has been operational since 1992 and currently supports an average of 350 patient visits per day. The new messaging system permits a provider to send a message to the next provider who will be caring for a patient. The messages can be sent to any provider offering care in the future, or they can be directed to future visits with a particular clinical service. In contrast to traditional electronic mail systems, messages are not directed to specific providers or groups of provider. Messages are instead directed to a specific clinical event, namely a patient's visit to an appropriate clinic. Messages are displayed when a patient returns for a designated visit, both as part of a pre-printed progress note upon which a provider documents the visit and as part of a hypertext-based general information display in an electronic medical record. The messaging system helps providers ensure that subsequent providers caring for their patients will be alerted to pertinent aspects of a patient's care. It also similarly helps providers quickly gain familiarity with those issues prior providers had felt were important to highlight or did not want to risk being overlooked.

Protein binding of hemoglobin (Hb) and bone marrow was used to compare in vivo reactions of 3 electrophilic metabolites of benzene, i.e., benzene oxide and 1,2- and 1,4-benzoquinone (1, 2-BQ and 1, 4-BQ), in F344 rats and B6C3F1 mice. Following a single p.o. administration of a mixture of [14C]- and [13C6]benzene between 50 and 400 mg/kg body weight, cysteine adducts of benzene oxide, 1,2-BQ, and 1,4-BQ were assayed, and the proportions of cysteine-bound adducts to total protein binding were estimated. Although dose-related production of each adduct was seen, large differences were observed between species and tissues. With rat Hb, benzene oxide adducts represented 27% of the total Hb binding and 73% of the cysteinyl binding, whereas quinone adducts represented relatively small proportions. However, with mouse Hb, the 1,4-BQ adducts accounted for 5.5% of the total Hb binding and 12.2% of the cysteinyl binding, while 1,2-BQ and benzene oxide each accounted for less than 3% of the total. In the bone marrow of both rats and mice, BQ adducts were more abundant than those of benzene oxide. However, adducts of 1,2-BQ predominated in rat marrow (9% of binding), whereas adducts of 1,4-BQ were more abundant in the mouse (21% of binding). The average blood concentrations of 1,4-BQ were estimated from the adduct levels and reaction-rate constants to be 2-5-fold higher in the mouse than in the rat. This work suggests that BQ binding is favored over that of benzene oxide in the bone marrow; however, high background levels of BQ adducts, observed with Hb and bone marrow proteins, suggest that any toxic effects of the quinones should only arise from high exposures to benzene.

Investigations have suggested that owing to the effects of autocorrelation and/or non-stationary behaviour exposure variability increases with the number of days between measurements. This study confirmed such increasing variability with the interval between observations in a collection of occupational data sets after controlling for factors likely to contribute to variability and for sample size. Consecutive shift-long exposure measurements for 53 workers from five different data sets in 123 time series were analysed. When the data were combined a clear increasing trend in the variance was observed with interval, but a breakdown by data set revealed that this trend was present in only two of the five data sets. The effect was further isolated in 30% of the workers who contributed data and in 29% of the total number of time series analysed. Amongst the data where the trend was evident the combination of autocorrelation and non-stationary behavior explained the increase in 64% of the time series. Significant autocorrelation was detected for a small group of workers in only one of the data sets and for a minority of cases amongst workers who contributed more than one time series to the analysis. Thus, autocorrelation of shift-long exposures does not appear to be pervasive and is unlikely to present significant problems when implementing statistically-based sampling strategies. On the other hand, the issue of non-stationarity remains equivocal. Although only a small proportion of time series was found to be non-stationary, the period investigated was short (around 30 days) and it remains to be seen whether the problem is more pronounced over longer time scales.

This study employed a longitudinal sampling design to obtain measurements of exposure and exhaled air from all members of a cohort several times over the course of one year. Styrene in exhaled air correlated well with styrene in breathing zone air. Both smoking and exposure to styrene appear to have contributed significantly and separately to increased SCEs. Early results imply that SCEs were somewhat more highly correlated with styrene in exhaled air than in breathing zone air.

The present state of empirical knowledge concerning neutron-star masses is reviewed on the basis of information obtained for the nine known X-ray pulsars in binary systems. Pulse profiles and other pulse parameters of these X-ray pulsars are examined, and allowable mass ranges are estimated for four X-ray pulsars in binary systems as well as for the binary pulsar PSR 1913+16. The approximate mass ranges obtained include 1.2 to 2.4 solar masses for 3U 0900-40, 0.7 to 4.3 solar masses for Cen X-3, 0.8 to 1.8 solar masses for SMC X-1, 0.0 to 2.3 solar masses for Her X-1, and either 1.4 to 1.8 solar masses or 0.0 to 1.8 solar masses for PSR 1913+16 if the companion is a normal white dwarf or some other type of star, respectively. Theoretical implications of these results are briefly considered.

Much of the data collected by industrial hygienists on levels of airborne contaminants in the workplace is of marginal relevance to the needs and interests of physicians practicing occupational medicine. Several factors influence data collection. Regulatory agencies require rigid interpretation of exposure levels, yet concentrations of contaminants in the air environment vary considerably. This discrepancy suggests a different approach to dealing with the regulatory problem, one which recognizes its inherent statistical nature. Increased attention also should be devoted to basing sampling intervals more directly on toxicological measurements. These changes would result in the collection of environmental data of greater relevance to physicians, toxicologists and epidemiologists because such information would allow more realistic estimates of the hazard of a cumulative exposure for a given work population.

The 32P-postlabelling procedure has been used to detect styrene oxide (SO)-DNA adducts. Reactions of SO with DNA and dGMP in vitro produced adducts that were similar, indicating that dGMP was the primary base for modification in DNA. Two SO adducts were also detected in DNA isolated from lymphocytes of a styrene-exposed worker but not in DNA from an unexposed worker. These results indicate that 32P-postlabelling can be used for quantification of DNA adducts in workers exposed to styrene.

The effect of ethanol on testosterone-5 alpha-A-ring reductase activity was studied in the whole homogenate and/or subcellular fractions (microsomes and cytosol) of buccal mucosa, gingiva, liver and prostate from intact ethanol-fed (36% of dietary calories were given as ethanol for up to 360 days) and pair-fed control rats. An increased enzyme activity was found in the hepatic, prostatic and gingival homogenates from ethanol-fed rats. No difference in the enzyme activity was seen in the homogenates of buccal mucosa. However, when the buccal mucosal microsomal fraction was used a significant (P less than .005) increase in the enzyme activity was found in the ethanol-fed rats. It was determined that the lack of an increase in 5 alpha-reductase activity in the buccal mucosal homogenates from ethanol-fed rats was due to the presence of a cytosolic inhibitor of this enzyme. Enzyme kinetics showed a decrease in the velocity in correlation with the increasing concentration of cytosolic inhibitor (Vmax control = 1.9 and Vmax ethanol = 1.7, 1.45 and 1.0 nmol, respectively). The apparent Km (0) and Kp (1--3) values were similar for all combinations (4.5 x 10(-5) M). In addition, a similar Ki constant (2.2 mg of cytosolic protein) was found for different testosterone concentrations. These results suggest that the ethanol-induced cytosolic inhibitor in buccal mucosa combines with the enzyme, independent of the substrate and inhibits it by an allosteric mechanism. Studies using dialysis, heating and tryptic digestion suggests that the inhibitor is a protein.