Angular momenta in binary systems

The correlations angular momentaL to massesM are studied for different types of spectroscopic binaries. The functionsL=AM ^b have the coefficientb with the values expected from a Keplerian mechanics, but the valuesA(q, T), A(q, a), A(q, v), associated tob=5/3, 3/2, and 2, respectively, are given (statistically speaking) by multiples or submultiples of discrete values of: the mass ratiosq, the semi-major axesa, periodsT, and velocitiesv of the reduced mass. This indicates the existence of a discrete unit of actionL=(1/2)×potential energy xperiod. Postulates about equivalent states of angular momenta for different orbital parameters are introduced, being this coherent with the analysis of the up-to-date data. Among other examples of the application of such equivalence postulates, we haveL(M) (W-type of the WUMa systems)L(M) (main group of the Algol binaries). The quantum units of action seen here are equivalent to those seen in the solar system in one of our previous works. From comparisons with galaxies and single stars, it is evidence that there is not an unique universal functionL=AM ^b, when the fine structure of the relation is analysed: each type of object has its own coefficients,A, b. It sems to be that there are an upper and a lower limit for all the possible functions. The upper limit isL=A _gM^5/3, withA _g1 associated to periodsT Hubble time, and the lower limit isL=GM ^2/c, with 1. The existence of the upper limit can be investigated with studies of pairs of galaxies, and the lower limit can be tested with analysis of single G, K, M stars. The quantical hypothesis introduced here can be checked definitely, when available larger samples of data with low errors, with similar quality as the selected list of almost 80 eclipsing binaries (mainly detached systems) analysed here.     

Properties of theβ pictoris disc deduced from optical imaging polarimetry

The asymmetries in the brightness structure and levels of polarization between the two sides of the Pic disc are discussed. The possibility of these differences being caused by a planet, or planets, within the circumstellar disc is investigated.     

The spiral structure in the inner parts of the Galaxy

The spiral structure of the inner parts of the Galaxy is studied using 21 cm line data and stellar data. To study the neutral hydrogen distribution in the galactic layer a parameter =(dV/dr) proportional to the mean densities is calculated using a first approximation for the velocity gradients due to differential rotation.The obtained distribution (R, Z) shows spiral features completely consistent with the early star distribution and with the Hii regions. The corrugation effect of the galactic layer is observed in all the studied zones in neutral hydrogen and in the distribution of the OB stars in the Carina zone.The pattern obtained indicates four spiral arms for the inner parts of the Galaxy, three of which are identified also in the stellar data (arms -I, -II, and -III) and the more distant -IV in Hii regions.The local arm according to the stellar data of Kilkennyet al. forms a feature completely similar to the arms -I and -II and there are no indications that this arm is a special material branch between two main spiral arms as has been supposed in order to conciliate the neutral hydrogen pattern with the stellar distribution.The pitch angles for the spiral arms are approximately 13°–17°.The observed wave form distribution of the hydrogen cloud layer is completely consistent with the theoretical predictions of Nelson (1976) but there are no indications of such an effect in the intercloud hydrogen. The corrugated cloud layer has a width of 100 pc, a wave amplitude of 70 pc, and a wavelength which grows with the galactic center distance (approx. 2 kpc in the zones next to the galactic nucleus and 2.6–3.0 kpc in the zones next to the Sun). To each wavelength correspond two spiral arms. The spiral features in our Galaxy show characteristics quite similar to the features in the Andromeda nebula, not only in the component materials (neutral hydrogen, Hii regions and possibly also dust and stars) but also in their kinematics.     

Spatio-temporal patterns of abundance,size structure and body condition of Atherina boyeri (Pisces: Atherinidae) in a small non-tidal Mediterranean lagoon

Sand smelt, Atherina boyeri, is a very abundant, widespread, locally harvested species, able to successfully survive and reproduce over a wide range of abiotic conditions and aquatic ecosystem types. In the North Sea and in the Mediterranean Sea transitional ecosystems its life history is well known, but very little information is available about the influence of intra-ecosystemic abiotic gradients on micro-scale patterns of distribution, body size and condition of individuals. In a small non-tidal Mediterranean lagoon, the cohorts' structure and evolution of sand smelt was described and the temporal and spatial variability of abundance, size structure and body condition was addressed. The study was carried out at the Acquatina lagoon (Lecce, Italy) where four stations, situated in two habitat types along a confinement gradient, were sampled twice per month for one year with fyke nets. The abundance of collected individuals was very high throughout the sampling period, with a peak in Summer and a constant decrease afterwards. Measured Standard Length ranged from 20 to 90 mm and the majority of individuals were estimated to be within 2 years old. The confined station resulted more abundantly colonized, especially by smaller size classes, and characterized by a narrower size frequency distribution. Also relative body condition showed significant spatial variations, with larger individuals having a better condition than smaller ones where optimal temperature and dissolved oxygen levels were available. Size-specific temporal patterns of body condition followed the seasonal climatic oscillations and the species' cycle of growth and reproduction, with larger individuals reaching higher fatness than smaller ones during Autumn and Winter, thus having more chances to survive and contribute to the reproductive effort. The results of the present study emphasised that, even at a very small scale, the presence of strong environmental gradients can drive movements, habitat preference and condition of individuals and thus promote an intra-ecosystemic spatial heterogeneity comparable to that observed between ecosystems at the land–ocean or geographical scale.     

High environmental salinity reduces the reproductive potential of the spider crab Maja brachydactyla (Decapoda,Majidae)

The spider crab Maja brachydactyla is an important fisheries species in Europe. Adults were sampled in Ría de A Coruña (NW Spain) and transported to IRTA rearing facilities. Salinity and photoperiod changes and their effect on reproduction were tested in the laboratory. The number of newly hatched larvae per batch (presence of actively swimming newly hatched larvae in a broodstock tank) was counted and sampled to estimate dry weight and proximal composition. Keeping spider crab broodstock in a high salinity environment (38 ppt) significantly reduced the number of newly hatched larvae, reaching up to fivefold difference in winter. The number of newly hatched larvae produced under a natural photoperiod was 10‐fold higher than those produced using a fixed photoperiod at 34 ppt salinity during winter. No clear pattern of changes in larval dry weight, protein, lipid or carbohydrate composition was observed under the environmental conditions tested. The results show that the salinity used for broodstock maintenance, especially during the embryonic development, is an important factor causing changes in larval production of M. brachydactyla and with potential implications for recruitment success.     

Fingerprinting TCE in a bedrock aquifer using compound-specific isotope analysis

A dual isotope approach based on compound-specific isotope analysis (CSIA) of carbon (C) and chlorine (Cl) was used to identify sources of persistent trichloroethylene (TCE) that caused the shut-down in 1994 of a municipal well in an extensive fractured dolostone aquifer beneath Guelph, Ontario. Several nearby industrial properties have known subsurface TCE contamination; however, only one has created a comprehensive monitoring network in the bedrock. The impacted municipal well and many monitoring wells were sampled for volatile organic compounds (VOCs), inorganic parameters, and CSIA. A wide range in isotope values was observed at the study site. The TCE varies between -35.6‰ and -21.8‰ and from 1.6‰ to 3.2‰ for δ(13) C and δ(37) Cl, respectively. In case of cis-1,2-dichloroethene, the isotope values range between -36.3‰ and -18.9‰ and from 2.4‰ to 4.7‰ for δ(13) C and δ(37) Cl, respectively. The dual isotope approach represented by a plot of δ(13) C vs. δ(37) Cl shows the municipal well samples grouped in a domain clearly separate from all other samples from the property with the comprehensive well network. The CSIA results collected under non-pumping and short-term pumping conditions thus indicate that this particular property, which has been studied intensively for several years, is not a substantial contributor of the TCE presently in the municipal well under non-pumping conditions. This case study demonstrates that CSIA signatures would have been useful much earlier in the quest to examine sources of the TCE in the municipal well if bedrock monitoring wells had been located at several depths beneath each of the potential TCE-contributing properties. Moreover, the CSIA results show that microbial reductive dechlorination of TCE occurs in some parts of the bedrock aquifer. At this site, the use of CSIA for C and Cl in combination with analyses of VOC and redox parameters proved to be important due to the complexity introduced by biodegradation in the complex fractured rock aquifer. It is highly recommended to revisit the study when the municipal well is back into full operation.     

Rapid Holocene hydrologic change along boreal treeline revealed by δ13C and δ18O in organic lake sediments, Northwest Territories, Canada

Analysis of ¹⁸O_cellulose, ¹³C_{organic matter}, and ¹³C_cellulose at about 100 year intervals from organic matter deposited in Toronto Lake, Northwest Territories, Canada, revealed an 8000-year history of rapid, post-glacial hydrologic change at the treeline zone. Several mid-Holocene phases of enriched ¹³C_org and ¹³C_cell, caused by elevated lake productivity, declining [CO_2(aq)], and closed basin conditions, were abruptly terminated by intervals of open hydrology recorded by sharply depleted ¹⁸O_cell. Two of these events, at 5000 and 4500 BP, are correlated with increased total organic content and Picea mariana pollen concentration, which indicate that high levels of productivity were also accompanied by northern treeline advances. A third treeline advance at about 2500 BP is also marked by an apparent outflow event from Toronto Lake, but this was not associated with ¹³C_org/cell enrichment in the sediment record because rapid and substantial lake water renewal probably prevented productivity-driven enrichment of the dissolved inorganic carbon and replenished the CO_2(aq) supply to thriving phytoplankton. However, high sediment organic content during this period suggests increased productivity. Increases in the inflow:evaporation ratio at about 6500 and 3500 BP were also sufficient to cause Toronto Lake to overflow but the prevailing climate during these periods apparently did not favour appreciable northward treeline migration or changes in lake productivity.This is the 14th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers