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A spacecraft's thermal protection system (TPS) is required to survive the harsh environment experienced during reentry. Accurate thermal modeling of the TPS is required to since uncertainties in the thermal response result in higher design margins and an increase in mass. The Radiant Heat Test Facility (RHTF) located at the NASA Johnson Space Center (JSC) replicates the reentry temperatures and pressures on system level full scale TPS test models for the validation of thermal math models. Reusable TPS, i.e. tile or reinforced carbon-carbon (RCC), have been the primary materials tested in the past. However, current capsule designs for MPCV and commercial programs have required the use of an ablator TPS. The RHTF has successfully completed a pathfinder program on avcoat ablator material to demonstrate the feasibility of ablator testing. The test results and corresponding ablation analysis results are presented in this paper.

The analyses of δ13C and δ18O of gas hydrate-associated sediments from two cores on Hydrate Ridge in Cascadia convergent margin offshore Oregon, eastern North Pacific show the values of δ13C from −29.81‰ to −48.28‰ (PDB) and δ18O from 2.56‰ to 4.28‰ (PDB), which could be plotted into a group called typical carbonate minerals influenced by the methane in cold venting. Moreover, the values of δ13C and δ18O show a consistent trend in both cores from top to bottom with increasing of δ13C and decreasing of δ18O. This trend could be explained as an effect caused by the anaerobic oxidation of methane (AOM) in depth and the oxygen fraction during the formation of gas hydrate in depth together. These characteristics of δ13C and δ18O indicate that the gas hydrate-associated sediments are significantly different from the normal marine carbonates, and they are deeply influenced by the formation and evolution of gas hydrate. So, the distinct characteristics of δ13C and δ18O of gas hydrate-associated sediments could be undoubtedly believed as one of parameters to determine the presence of gas hydrates in other unknown marine sediment cores.

Ferro-manganese nodules of the western Baltic Sea reveal enhanced heavy metal concentrations since the end of the 19th century and are therefore potentially useful for retrospective monitoring of the heavy metal pollution history. However, only Zn shows a significant rise, even though Cu is also introduced to the western Baltic Sea by natural and anthropogenic sources. This study focused on geochemical considerations to evaluate the mechanism responsible for the predominance of Zn in ferro-manganese nodules compared to Cu. The particulate and dissolved metal fractions in the water column, in the fluffy layer (an approximately 2-cm-thick sediment layer situated at the sediment–water interface) and in the pore water adjacent to ferro-manganese nodules were studied. The analysis of the dissolved fraction and speciation studies were carried out using cathodic stripping voltammetry (CSV). The particulate fraction and the pore water were analyzed via graphite furnace–atomic absorption spectroscopy (GF–AAS) and inductively coupled plasma–optical emission spectroscopy (ICP–OES). The fluffy layer provides high quantities of Mn, Fe, Zn, and Cu to the dissolved fraction of the bottom water during the stratification period. Hence, the signal manifested in the ferro-manganese nodules consists of newly emitted elements on top of the amount collected in the fluffy layer over many years and remobilized throughout the stratification. Trace elements with the tendency to form weak inorganic complexes in the water column, like Zn, are more likely to be incorporated in ferro-manganese nodules and therewith document the anthropogenic metal input, while elements which tend to form strong organic complexes such as Cu are scavenged by particulate organic matter in the water column and the fluffy layer.

Based on a superconducting magnetic energy storage (SMES) a long-pulse klystron modulator has been designed for use in the TESLA Test facility (TTF) at DESY, Hamburg. A prototype with an output power of 25 MW is under development at Forschungszentrum Karlsruhe in cooperation with the office of engineering IbK at Karlsruhe. The system will deliver pulses of up to 130 kV and 1.7 ms pulse length with a flat top of /spl plusmn/0.5% at a repetition rate up to 10 Hz. Some of this new system's main features are the highly dynamic SMES (100 T/s), a switched-mode high voltage power supply (rated 14 kV/45 A), a fast thyristor power switch and an IGCT power switch rated 2.6 kA/14 kV. This demonstration system is to serve alternatively two klystrons of 5 MW RF output or one multibeam klystron of 10 MW RF output. A first set of the system components had been arranged to form a model of the modulator and 1 MW pulses were generated. The SMES and its cryostat have undergone initial testing at DC operation. The data acquisition and control system DOOCS under development at DESY has been adapted to the authors' computer and experimental environment.

Disturbances generated in the power system by the feedback of fluctuating loads can be reduced by application of a fast reacting SMES based power compensator. A demonstrator using a NbTi solenoid had been developed and tested in the field at an earlier time. This paper reports on the second step, which is the replacement of the solenoid by a ten coil toroid with low fringing magnetic field. The paper concentrates on Europe's first toroidal SMES in operation. Its design, construction, and test are described. A maximum of 420 kJ energy was stored, when the magnet system reached the short sample current value after one training step.

Hydrogen sulfide discharge at cold seep sites is recorded as enrichment in the barium to calcium (Ba/Ca) ratio in shells of vesicomyid clams collected live from cold seeps in Monterey Canyon and the Cascadia margin. A direct relationship between increased Ba fluxes from cold seeps and Ba incorporation into shells was established for the Cascadia margin site. For the Monterey canyon site, a 2-yr episode of high fluid flow centered on 1992 was inferred from coherent changes in the Ba/Ca profiles of threeCalyptogena kilmerishells. Comparison with precipitation and d 18 O data indicates that this high-flow period may have been driven by an increase in rainfall after the 1988‐1990 California drought. High-resolution records preserved in clam shells are shown to be useful in elucidating characteristics, history, and possible mechanisms driving fluid discharge at continental margin seeps, thus establishing their potential use as paleotracers of fluid seepage events. An extensive set of geophysical and geochemical measurements is currently available to document the flow and expulsion of fluids at transform and convergent margins. It is now recognized that such fluid discharge has far-reaching implications that include hydrocarbon prospecting, benthic ecosystem structure and function, and groundwater research (Moore 1999). At present, we are unable to incorporate geochemical data from cold seeps to models quantifying their effects on marine geochemical budgets because we lack a clear understanding of the spatial and temporal variability of these systems and of the mechanisms responsible for the advective transport. However, vent macrofauna may afford such an opportunity by recording in their shells the immediate environment in which they grow and thereby allowing us to reconstruct the variability in fluid discharge rates. Vesicomyid clams live in association with sites of sulfide 1

In this article we report patterns of task-to-task vagal tone change across multiple language and play tasks as well as associations between these patterns of task-to-task vagal tone change and language and play performance in 20-month-old girls and boys. Although initially different in vagal tone suppression during solitary play, girls and boys exhibited similar group patterns of vagal reengagement during successive language and play tasks with their mothers and with an experimenter. In terms of individual differences, vagal suppression during solitary play and vagal reengagement during social interactive tasks predicted language and play performance. Gender differences emerged in patterns of predictive relations: Task-to-task vagal changes predicted primarily play performance in girls and language performance in boys. These findings expose the effects of social context on directional changes in task-to-task vagal tone and speak to the functional role of appropriate vagal regulation in young children's language and play performance.

In this prospective longitudinal study, vagal tone and heart period were measured at 2 months and at 5 years in children and their mothers to evaluate the development of vagal regulation at rest and during an environmental task. Child baseline vagal tone and heart period were discontinuous; mother baseline vagal tone was discontinuous, but heart period was continuous. Group mean baseline-to-task change in vagal tone and heart period were continuous in both children and mothers. Children reached adult levels of baseline vagal tone by 5 years and did not differ from their mothers in baseline-to-task change in vagal tone or heart period. Baseline vagal tone tended to be stable, but baseline heart period and baseline-to-task change in vagal tone and heart period were unstable in children; both were stable in mothers. Baseline-to-task change in vagal tone showed consistent child-mother concordance. These findings contribute to understanding psychophysiological development, especially the ontogenesis of the vagal system and its regulatory capacity.

The effluent activity from a well-known pockmark structure in Eckernforde Bay was monitored for methane, salinity, and temperature signals in the water column intermittently over three years between 1991, 1993 and 1994. Groundwater discharge from an aquifer into the brackish waters of the western Baltic, dilutes bottom water salinities to values as low as 2.9‰. Seasurface height and the amount of precipitation preceding sampling periods by 5 days correlated significantly with the rate of groundwater discharge. Concentrations of methane in bottom water at the pockmark site were strongly influenced by seepage intensity. At two sampling sites (control and pockmark site) distinctly lower methane concentrations were observed towards the sea surface, although the entire water body of Eckernforde Bay appears to be affected by methane seeping from the sediments. This is supported by high methane concentrations above equilibrium with atmospheric methane throughout most of the year. Maximum concentration above the equilibrium value in surface waters was 2800‰. Methane flux from surface waters into the atmosphere follows strong seasonal variations, with maximum values in the winter (200–400 μmol m-2 d-1). The study reveals the important role of coastal oceans in the global methane cycle, as an intense but variable source of methane of largely unknown magnitude.

In the newborn period, infants prenatally exposed to cocaine and other drugs show low scores on the Neonatal Behavioral Assessment Scale. Beyond that period, research is limited on the effects of prenatal drug exposure on neurobehavioral functioning. In this study we compared infants exposed to cocaine and other drugs and control infants from low socioeconomic backgrounds on measures of neurobehavioral functioning during neuromotor assessment at 1, 4 and 7 months of life. None of the measures of neurobehavioral functioning showed any significant group differences. This study did not support the hypothesis of disrupted neurobehavioral functioning beyond the neonatal period in infants exposed to drugs prenatally.

Fourteen boys who were exposed to opiates in-utero (drag exposed) maintained their index finger in a static, weight-forced position while attempting to maintain a stylus at a fix point producing intentional microtremors. After 2.5 minutes, significant increases in tremor were recorded in mean peak (6 Hz) amplitude while accuracy of sustaining this response was significantly reduced. Age matched boys (ages 7–12) who were raised in an environment in which drags were used but were not directly exposed in-utero (lifestyle group N = 13) or a standard control group (N = 12), did not show similar changes over time. Resting or postural-extended tremor did differ among groups. Alcohol, marihuana, or tobacco usage by the mother or birth weight of the child did not predict subsequent group differences in tremor. Both biological and environmental variables plus type and sensitivity of measurement used are critical elements for describing long-term, potential residual drug effects in children, especially as t...

The analysis of meconium for cocaine and metabolites has proved to be a reliable method for the detection of fetal cocaine exposure. Better sensitivity and a larger gestational window of detection have been demonstrated for meconium testing as compared with neonatal urine testing. Cocaine and cocaine metabolites, including benzoylecgonine, ecgonine methyl ester, cocaethylene, norcocaine, benzoylnorecgonine, and m-hydroxybenzoylecgonine, have been identified in meconium. The origin of these metabolites, whether maternal or fetal, has not been established. This study was conducted to compare the disposition of cocaine and metabolites in meconium from fetuses exposed to cocaine with that of urine from cocaine abusers. Meconium specimens were obtained from six neonates of mothers positive for cocaine use by urinalysis or self-reporting or both during pregnancy. Urine specimens were obtained from 17 adult female and 17 adult male cocaine users enrolled in a treatment program. Specimens were analyzed by gas chromatography-mass spectrometry for cocaine and 12 related analytes. The following analytes were identified and measured in meconium and urine: anhydroecgonine methyl ester; ecgonine methyl ester; ecgonine ethyl ester; cocaine; cocaethylene; benzoylecgonine; norcocaine; norcocaethylene; benzoylnorecgonine; m-and p-hydroxycocaine; and m-and p-hydroxybenzoylecgonine. In addition, both m-and p-hydroxybenzoylecgonine were found to exhibit approximately equal cross-reactivity with benzoylecgonine in the EMIT and TDx assays. The presence of p-hydroxybenzoylecgonine in meconium suggested that this newly identified metabolite, like m-hydroxybenzoylecgonine, might serve as a valuable marker of fetal cocaine exposure during pregnancy. The presence of cocaine and anhydroecgonine methyl ester in meconium was attributed to transfer across the placenta from the mother. However, the origin of the hydrolytic and oxidative metabolites of cocaine could not be established because they were also identified in urine specimens of adult female cocaine users and could have arisen in meconium from either fetal or maternal metabolism.

This study examined behavioral and physiologic regulation in 14 full-term neonates who were exposed to cocaine antenatally. A group of 14 non-cocaine-exposed infants served as controls. Data on behavioral state, cardiac patterning (heart period and vagal tone), and habituation to a standardized stimulus were collected. There were no differences between cocaine-exposed and nonexposed infants in heart period or vagal tone during an undisturbed period. There were significant differences in behavioral state regulation: Cocaine-exposed infants displayed significantly greater state lability and shorter sleep bouts, fussed or cried more often, and spent less time asleep and more time in transitional states. Both groups responded to an auditory stimulus with shorter heart period, but cocaine-exposed neonates demonstrated a larger response. In addition, cocaine-exposed neonates displayed less behavioral response decrement to repeated presentations of the stimulus. Although there are limitations to attribution of these results to cocaine alone, the results are discussed in relation to prevailing clinical impressions of cocaine-exposed neonates.

Results of C 14 determinations in surface water from the Pacific were in agreement with those reported by Rafter and Fergusson. However, abnormal C 14 concentrations seem to exist locally, for which no oceanographic explanation can be given. It seems premature to draw conclusions from existing determinations as to the rate of increase of C 14 in surface ocean water resulting from the uptake of C 14 produced in the atmosphere by atomic bombs. Samples from a constant depth of about 3,500 meters show a C 14 content decreasing from south to north. This decrease may be attributed to radioactive decay of C 14 during the time of migration. From this the northward component of the rate of water movement of about 0.06 cm/sec can be calculated. The C 13 determinations, for the purpose of correcting the C 14 values for isotope fractionation effects, were found to be remarkably consistent, although made on reburned acetylene. DOI: 10.1111/j.2153-3490.1960.tb01330.x

From a comparison of C 14 /C 12 and C 13 /C 12 ratios in wood and in marine material and from a slight decrease of the C 14 concentration in terrestrial plants over the past 50 years it can be concluded that the average lifetime of a CO 2 molecule in the atmosphere before it is dissolved into the sea is of the order of 10 years. This means that most of the CO 2 released by artificial fuel combustion since the beginning of the industrial revolution must have been absorbed by the oceans. The increase of atmospheric CO 2 from this cause is at present small but may become significant during future decades if industrial fuel combustion continues to rise exponentially. Present data on the total amount of CO 2 in the atmosphere, on the rates and mechanisms of exchange, and on possible fluctuations in terrestrial and marine organic carbon, are inadequate for accurate measurement of future changes in atmospheric CO 2 . An opportunity exists during the International Geophysical Year to obtain much of the necessary information. DOI: 10.1111/j.2153-3490.1957.tb01849.x

When, in 1950, Willard Libby and his coworkers obtained their first radiocarbon ( 14 C) dates, C. W. Ferguson at the University of Arizona Tree Ring Laboratory was working on establishing a continuous tree ring series for the newly discovered bristlecone pine Pinus aristata . Before his untimely death in 1986, he had extended the series nearly 8000 years into the past. From the Ferguson series I obtained for 14 C determinations wood samples grown at various times. Also, two other laboratories obtained such samples. For B.C. times in particular, our measured 14 C-values that deviated consistently from those calculated from tree rings, and the deviations increased with age. This general trend was observed by other laboratories, but the presence of deviations from these trends, of the so-called ‘wiggles’, was questioned by other workers. To me these wiggles indicated the existence of a most interesting geophysical parameter valid for the whole terrestrial atmosphere. Fourier spectra obtained at my request by Kruse in 1972, and by Neftel, demonstrated the consistency of the results, and supported my contention that the secular variations of 14 C in atmospheric CO 2 are related to variations of solar activity.

Indiplon [N-methyl-N-[3-[3-(2-thienylcarbonyl)-pyrazolo[1,5-alpha]pyrimidin-7-yl]phenyl]acetamide; NBI 34060] is a positive allosteric GABA(A) receptor modulator that is under development for the treatment of insomnia. This study compared the abuse potential of indiplon, a compound with preferential affinity for GABA(A) receptors containing an alpha(1) subunit, with triazolam in 21 volunteers with histories of drug abuse. Placebo, triazolam (0.25, 0.5, and 0.75 mg), and indiplon (30, 50, and 80 mg) were studied in counterbalanced order under double-blind conditions at two different residential research facilities. Both drugs impaired psychomotor and cognitive performance and produced similar dose-related increases in participant and observer ratings of drug strength. The onset of action of both drugs was rapid (30 min); however, the duration of action of indiplon (3-4 h) was shorter than that of triazolam (4-6 h). The profiles of subjective effects of triazolam and indiplon were similar; however, a maximum of 52% of participants identified indiplon as a benzodiazepine or barbiturate, compared with 81% of participants after 0.75 mg of triazolam. On participantrated subjective effects relevant to sedation, the slope of the triazolam dose-effect curve was significantly steeper than that of indiplon. Neither the largest doses of indiplon and triazolam nor the slope of the indiplon and triazolam dose-effect curves were significantly different from each other on any of the same-day or next-day measures of positive drug effects or next-day measures of reinforcing effects. Together, these data suggest that although the abuse potential of indiplon is not different from that of triazolam at these doses, psychomotor and cognitive impairment after large doses of indiplon might be less.

Context Ramelteon is a novel MT 1 and MT 2 melatonin receptor selective agonist recently approved for insomnia treatment. Most approved insomnia medications have potential for abuse and cause motor and cognitive impairment. Objective To evaluate the potential for abuse, subjective effects, and motor and cognitive–impairing effects of ramelteon compared with triazolam, a classic benzodiazepine sedative-hypnotic drug. Design In this double-blind crossover study, each participant received oral doses of ramelteon (16, 80, or 160 mg), triazolam (0.25, 0.5, or 0.75 mg), and placebo during approximately 18 days. All participants received each treatment on different days. Most outcome measures were assessed at 0.5 hours before drug administration and repeatedly up to 24 hours after drug administration. Setting Residential research facility. Participants Fourteen adults with histories of sedative abuse. Main Outcome Measures Subject-rated measures included items relevant to potential for abuse (eg, drug liking, street value, and pharmacological classification), as well as assessments of a broad range of stimulant and sedative subjective effects. Observer-rated measures included assessments of sedation and impairment. Motor and cognitive performance measures included psychomotor and memory tasks and a standing balance task. Results Compared with placebo, ramelteon (16, 80, and 160 mg) showed no significant effect on any of the subjective effect measures, including those related to potential for abuse. In the pharmacological classification, 79% (11/14) of subjects identified the highest dose of ramelteon as placebo. Similarly, compared with placebo, ramelteon had no effect at any dose on any observer-rated or motor and cognitive performance measure. In contrast, triazolam showed dose-related effects on a wide range of subject-rated, observer-rated, and motor and cognitive performance measures, consistent with its profile as a sedative drug with abuse liability. Conclusion Ramelteon demonstrated no significant effects indicative of potential for abuse or motor and cognitive impairment at up to 20 times the recommended therapeutic dose and may represent a useful alternative to existing insomnia medications.

Mud diapirism is a common phenomenon of accretionary convergent margins but less common in erosive margins. Fluid venting associated with mud diapirism is of importance for the dewatering of the forearc and the resulting devolatilisation of the entire subduction zone. The margin offshore Costa Rica is today interpreted as erosive and subdivided into two major structural domains on grounds of the roughness of the downgoing plate: a smooth domain in the north where normal oceanic crust originating at the East Pacific Rise, and a rough southern domain where the margin is uplifted and fractured by the collision of the Cocos Ridge and numerous adjacent volcanic seamounts. These structural differences are reflected in differences in the output at the volcanic arc, dewatering mechanisms, and the abundance and geometry of mud mounds in the forearc. Diapiric mud mound occurrences in the smooth domain are most abundant in the middle and upper slope and apparently do not correlate with the maximum of compactional water release of the incoming sedimentary sequence. We invoke rapid changes in sedimentation rate and addition of accommodation space due to extensional faulting of the wedge to explain the observed mound distribution.

Submersible investigations of the Cascadia accretionary complex have identified localized venting of methane gas bubbles in association with gas hydrate occurrence. Acoustic profiles of these bubble plumes in the water column in the vicinity of Hydrate Ridge offshore Oregon provide new constraints on the spatial distribution of these gas vents and the fate of the gas in the water column. The gas vent sites remained active over the span of two years, but varied dramatically on time scales of a few hours. All plumes emanated from local topographic highs near the summit of ridge structures. The acoustic images of the bubble plumes in the water column disappear at water depths between 500 to 460 m, independent of the seafloor depth. This coincides with the predicted depth of the gas hydrate stability boundary of 510 to 490 m, suggesting that the presence of a hydrate skin on the bubble surface prevents them from rapid dissolution. The upper limit of the acoustic bubble plumes at 460 m suggests that dissolution of the residual bubbles is relatively rapid above the hydrate stability zone.

Respiratory sinus arrhythmia (RSA), a non-invasive indicator of vagal regulation of the heart, and heart period (HP) were monitored before, during, and after oral or gastric-tube bolus feedings in 32 preterm infants. Group 1 infants (n=15) wereor =30 weeks gestational age (GA) at birth (mean 28.3 weeks) and group 2 infants (n=17) wereor =31 weeks GA at birth (mean=33.2 weeks). Mean postmenstrual ages at the time of study were 33.5 +/- 2.3 (SD) weeks in group 1 and 33.9 +/- 1.6 (SD) weeks in group 2. RSA and HP decreased in both groups during feeding. However, postfeeding RSA and HP increased toward prefeed levels only for group 2 infants. In addition, RSA and HP changes during feeding were correlated only for group 2 infants. The results suggest that the preterm infant may experience a maturational lag in vagal function and in the influence of vagal activity on metabolic mechanisms (i.e. heart rate) related to ingestive needs. This maturational lag may contribute to continued feeding difficulties and may be a measurable marker of subtle neurodevelopmental problems.

This study investigates the role of physiological self-regulation (cardiac vagal tone) in information processing (habituation) in 81 infants. Nucleus ambiguus vagal tone (Vna, a measure of respiratory sinus arrhythmia) was used to index cardiac vagal tone. Physiological self-regulation was operationalized as the change in Vna from a baseline period of measurement to habituation. Decreases in Vna consistently related to habituation efficiency, operationalized as accumulated looking time (ALT), in all infants twice at 2 months and twice at 5 months; however, this relation was accounted for by infants who met an habituation criterion on each task. Among habituators, shorter lookers also had greater Vna suppression during habituation. Within-age and between-age suppression of vagal tone predicted ALT, but ALT did not predict suppression of vagal tone. Physiological self-regulation provided by the vagal system appears to play a role in information processing in infancy as indexed by habituation.

In this prospective longitudinal study, vagal tone and heart period were measured at 2 months and at 5 years in children and their mothers to evaluate the development of vagal regulation at rest and during an environmental task. Child baseline vagal tone and heart period were discontinuous; mother baseline vagal tone was discontinuous, but heart period was continuous. Group mean baseline-to-task change in vagal tone and heart period were continuous in both children and mothers. Children reached adult levels of baseline vagal tone by 5 years and did not differ from their mothers in baseline-to-task change in vagal tone or heart period. Baseline vagal tone tended to be stable, but baseline heart period and baseline-to-task change in vagal tone and heart period were unstable in children; both were stable in mothers. Baseline-to-task change in vagal tone showed consistent child-mother concordance. These findings contribute to understanding psychophysiological development, especially the ontogenesis of the vagal system and its regulatory capacity.

Gamma-aminobutyric acid (GABA) is present in the central nervous system of Aplysia californica (Gastropoda, Opisthobranchia) where its role as a neurotransmitter is supported by pharmacological, biochemical, and anatomical investigations. In this study, the distribution of GABA-immunoreactive (GABAi) neurons and fiber systems in Aplysia was examined by using wholemount immunohistochemistry and nerve backfill methods. GABAi neurons were located in the buccal, cerebral, and pedal ganglia. Major commissural fiber systems were present in each of these ganglia, whereas more limited fiber systems were observed in the ganglionic connectives. Some of the interganglionic fibers were found to originate from two unpaired GABAi neurons, one in the buccal ganglion and one in the right pedal ganglion, each of which exhibited bilateral projections. No GABAi fibers were found in the nerves that innervate peripheral sensory, motor, or visceral organs. Although GABAi cells were not observed in the pleural or abdominal ganglia, these ganglia did receive limited projections of GABAi fibers originating from neurons in the pedal ganglia. The distribution of GABAi neurons suggests that this transmitter system may be primarily involved in coordinating certain bilateral central pattern generator (CPG) systems related to feeding and locomotion. In addition, the presence of specific interganglionic GABAi projections also suggests a role in the regulation or coordination of circuits that produce components of complex behaviors.

In Eckernforde Bay (western Baltic Sea) pockmark structures are induced by groundwater seeping out of the sediment. On 3 occasions in winter and spring 1993-94 we investigated the influence of groundwater on the reduction of salinity, on porewater chemistry, and on bacterial activities (methane oxidation and sulphate reduction). In 2 out of 3 sampling campaigns groundwater discharge could be detected. The concentration gradients of Cl - and SO 4 = are moved towards the sediment surface by the vertical advection of groundwater during seep times. Without groundwater discharge the porewater chemistry resembled the control site. Compared to the control site, the methane oxidation and sulphate reduction rates were elevated at the pockmark site, reaching maximum values of 49 and 269 μmol l -1 d -1 respectively. The groundwater venting from the pockmark had an end member composition of 80 mM Na + , 1.0 mM Ca ++ and was depleted in Mg ++ . Due to mixing of these major cations along the groundwater/seawater interface, no CaCO 3 precipitation was found around the pockmark site.

The effects of incentive on sustained attention and autonomic regulation among boys exposed in utero to opiates were studied. Respiratory sinus arrhythmia (RSA), an indicator of autonomic regulation, was quantified during sustained attention in 3 groups of 7- to 12-year-old boys. RSA is a component of heart rate variability controlled by cortical influences and affected by changes in demand for attention. The Gordon Diagnostic System-Distractibility Task was performed with and without monetary reward. A cartoon task and a video game were used as measures of interest. Although opiate-exposed boys did not differ in performance as a function of incentive or interest, they had a tendency to perform more poorly overall across tasks. Alcohol exposure rather than opiate exposure covaried with autonomic regulation, with greater RSA decreases being associated with more alcohol exposure. Post hoc analyses revealed that the alcohol- and opiate-exposed boys responded with these hyperreactive RSA changes along with poorer performance.

Measurements of dissolved methane in the surface waters of the western Sea of Okhotsk are evaluated in terms of methane exchange rates and are used to assess the magnitude of seasonal variations of methane fluxes from the ocean to the atmosphere in this area. Methane concentrations northeast of Sakhalin were observed to range from 385 nmol L−1 under the ice cover in winter to 6 nmol L−1 in the icefree midsummer season. The magnitude of supersaturations indicates that this part of the Okhotsk Sea is a significant source for atmospheric methane. From the seasonal variation of the supersaturations in the surface waters it is evident that the air-sea exchange is interrupted during the winter and methane from sedimentary sources accumulates under the ice cover. According to our measurements an initial early summer methane pulse into the atmosphere of the order of 560 mol km−2 d−1 can be expected when the supersaturated surface waters are exposed by the retreating ice. The methane flux in July is approximately 150 mol km−2 d−1 which is of the order of the average annual flux in the survey area. The magnitude of the seasonal CH4 flux variation northeast of Sakhalin corresponds to an amount of 7.3 × 105 g km−2 whereby 74% or 5.4 × 105 g km−2 are supplied to the atmosphere between April and July. For the whole Sea of Okhotsk the annual methane flux is roughly 0.13 × 1012 g (terragrams), based on the assumption that 15% of the entire area emit methane. Variations of long-term data of atmospheric methane which are recorded at the same latitude adjacent to areas with seasonal ice cover show a regional methane pulse between April and July. The large-scale level of atmospheric methane in the northern hemisphere undergoes an amplitudinal variation of about 25 parts per billion by volume (ppbv) which translates into approximately 36 Tg. Thus the estimated 0.6 Tg of ice-induced methane dynamics in northern latitudes can hardly explain this seasonal signal. However, the effects of seasonal ice cover on pulsed release of methane appear strong enough to contribute, in concert with other seasonal sources, to characteristic short-term wobbles in the atmospheric methane budget which are observed between 50°N and 60°N.