Discovery of High Proper-Motion Ancient White Dwarfs: Nearby Massive Compact Halo Objects?

We present the discovery and spectroscopic identification of two very high proper-motion ancient white dwarf stars, found in a systematic proper-motion survey. Their kinematics and apparent magnitude clearly indicate that they are halo members, while their optical spectra are almost identical to the recently identified cool halo white dwarf WD 0346+246. Canonical stellar halo models predict a white dwarf volume density that is 2 orders of magnitude less than the rho approximately 7x10-4 M middle dot in circle pc-3 inferred from this survey. With the caveat that the sample size is very small, it appears that a significant fraction, approximately 10%, of the local dark matter halo is in the form of very old, cool, white dwarfs.     

Bioenergy potentials from forestry in 2050

The purpose of this study was to evaluate the global energy production potential of woody biomass from forestry for the year 2050 using a bottom-up analysis of key factors. Woody biomass from forestry was defined as all of the aboveground woody biomass of trees, including all products made from woody biomass. This includes the harvesting, processing and use of woody biomass. The projection was performed by comparing the future demand with the future supply of wood, based on existing databases, scenarios, and outlook studies. Specific attention was paid to the impact of the underlying factors that determine this potential and to the gaps and uncertainties in our current knowledge. Key variables included the demand for industrial roundwood and woodfuel, the plantation establishment rates, and the various theoretical, technical, economical, and ecological limitations related to the supply of wood from forests. Forests, as defined in this study, exclude forest plantations. Key uncertainties were the supply of wood from trees outside forests, the future rates of deforestation, the consumption of woodfuel, and the theoretical, technical, economical, or ecological wood production potentials of the forests. Based on a medium demand and medium plantation scenario, the global theoretical potential of the surplus wood supply (i.e., after the demand for woodfuel and industrial roundwood is met) in 2050 was calculated to be 6.1 Gm³ (71 EJ) and the technical potential to be 5.5 Gm³ (64 EJ). In practice, economical considerations further reduced the surplus wood supply from forests to 1.3 Gm³ year⁻¹ (15 EJ year⁻¹). When ecological criteria were also included, the demand for woodfuel and industrial roundwood exceeded the supply by 0.7 Gm³ year⁻¹ (8 EJ year⁻¹). The bioenergy potential from logging and processing residues and waste was estimated to be equivalent to 2.4 Gm³ year⁻¹ (28 EJ year⁻¹) wood, based on a medium demand scenario. These results indicate that forests can, in theory, become a major source of bioenergy, and that the use of this bioenergy can, in theory, be realized without endangering the supply of industrial roundwood and woodfuel and without further deforestation. Regional shortages in the supply of industrial roundwood and woodfuel can, however, occur in some regions, e.g., South Asia and the Middle East and North Africa.     

Time mean and variability of the scale-decomposed atmospheric water budget in a 25-year simulation of the Canadian Regional Climate Model over North America

The scaled-decomposed atmospheric water budget over North America is investigated through the analysis of 25 years of simulation by the Canadian Regional Climate Model (CRCM) driven by the NCEP–NCAR reanalyses for the period 1975–1999. The time average and time variability of the atmospheric water budget for the winter and summer seasons are decomposed into their large-scale and small-scale components to identify the added value of the regional model. For the winter season, the intra-seasonal transient-eddy variance is the main temporal variability. The large- and small-scale terms are of the same order of magnitude, and are large over both coasts and weak over the continent. For the summer season, the time–mean atmospheric water budget is rather different to that of winter, with maximum values over the south-eastern part of the continent. The summer intra-seasonal variance is about twice stronger than in winter and also dominates the variability, but the inter-monthly variance is non-negligible and can be in part associated to North American Monsoon System. Over the continent, the intra-seasonal climatological variance is dominated by the variability of the small scales. The small scales, that is those scales that are only resolved in the regional model but not in the reanalyses, contribute to the added value in a regional climate simulation. In the winter season, the added value of the CRCM is large and dominated by oceanic forcing, while in summer, it is dominant (larger than the large scales) and controlled mainly by convective processes.     

The behavior of vertically integrated boundary-layer winds

This research provides a study of the behavior of vertically integrated boundary-layer winds (IBLWs). This information should be helpful for both theoretical and practical applications, e.g., boundary-layer parameterization in general circulation models, air pollution models, and low-level parachuting operations. The study concerned itself with winds integrated up to a height of 300 m in the United States. The only data suitable for studying the behavior of IBLWs for such heights were measurements taken on tall towers. An extensive search indicated that data were readily available from only four towers instrumented to or above 300 m. These were located in rural locations in Texas, Oklahoma, Nevada, and South Carolina. At each location, means and coefficients of variation of IBLWs were computed, plotted as a function of time since sunrise/sunset, and compared. The research shows that IBLWs may differ appreciably in magnitude at different locations; may have considerable universality in behavior, and may also be ‘regionally’ dependent; and that IBLWs have a pronounced diurnal variation linked to sunrise/sunset time.     

The Precambrian of the Anti-Atlas (Morocco): A geochronological synthesis

Twenty total rock Rb/Sr isochrons ($\text{λ}{}^{87}\text{Rb}\text{= 1.47 · 10}{}^{\mathrm{?11}}\text{yr}{}^{\mathrm{?1}}$) and many individual data, mainly obtained by the K/Ar and Rb/Sr methods, on total rocks and minerals show that the orogenic story of the Precambrian of the Anti-Atlas, which was studied in its western and central parts, began with the Eburnean orogeny (1900-1650 m.y.). Up to now there is no good evidence of an older basement, even if the rather high initial ratio (0.707–0.709) of some Eburnean granites might suggest that such a basement exists at depth. There is also no geochronological evidence of plutonism until in early Panafrican time (680 m.y.) there started a period of intense magmatic and thermal activity which was ended by the emplacement of late post-tectonic granites at 530-520 m.y.The late Panafrican acid volcanism does not generally give suitable material for Rb/Sr dating, because of the great mobility of the radiogenic strontium in such a material even under very weak thermal conditions.     

Biologie und Bewirtschaftung des Seesaiblings (Salvelinus alpinus L.) im Zugersee

In recent years yields of the Alpine char fishery of Lake Zug have only been about 5% of traditional yields at the turn of the century. Major results of a biological investigation of the species are presented. Management implications based on the biological study, that should reverse the trend of diminishing yields, are made.     

Radiocarbon dates and late-Quaternary stratigraphy from Mamontova Gora,unglaciated central Yakutia,Siberia, U.S.S.R.

A fine exposure of perennially frozen ice-rich silt and associated flora and vertebrate fauna of late-Quaternary age exists at Mamontova Gora along the Aldan River in central Yakutia, Siberia, U.S.S.R. The silt deposit caps a 50-m-high terrace and consists of three units. An upper layer 1–2 m thick overlies a 10–15-m-thick brownish to black silt layer. The lower silt layer is greenish to gray and about 15 m thick. All the silt is well sorted with 60% of the particles falling between 0.005 and 0.5 mm in diameter and is generally chemically and mineralogically homogeneous. The middle unit contains may extinct vertebrate mammal remains and ice wedges. The lower unit contains little vegetation and no ice wedges. The silt is widespread and exists as a loamy blanket on terraces at various elevations on both sides of the lower Aldan River. The origin of the silt blanket of late-Quaternary age in central Yakutia has long been controversial. Various hypotheses have been suggested, including lacustrine and alluvial, as well as frost-action origins. It is sometimes referred to as loess-like loam. Péwé believes the silt at Mamontova Gora is loess, some of which has been retransported very short distances by water. The silt probably was blown from wide, braided, unvegetated flood plains of rivers draining nearby glaciers. The silt deposits are late Quaternary in age and probably associated with the Maximum glaciation (Samarov) and Sartan and Syryan glaciations of Wisconsinan age. On the basis of biostratigraphy, 10 radiocarbon dates, and their relation to the nearby glacial record, it is felt that the upper unit at Mamontova Gora is Holocene and the middle unit is Wisconsinan. The youngest date available from the middle unit at this particular location is 26,000 years. Dates greater than 56,000 years were obtained in the lower part of the middle unit. The lower unit is definitely beyond the range of radiocarbon dating and probably is older than the last interglacial. The sediment, fauna, ice wedges, stratigraphy, and age of perennially frozen slit deposits in central Alaska are remarkably similar to those of the deposits exposed in central Yakutia. Both areas consist of unglaciated rolling lowlands and river terraces surrounded by high mountains that were extensively glaciated in Pleistocene time. The glaciers extended from the high mountains to the edges of the ranges. In both regions, extensively braided, silt-charged rivers drained the mountains and flowed through the lowlands on their way to the sea. It follows that there should be a similar late-Quaternary history.     

Evaluation of heavy metals and arsenic speciation discharged by the industrial activity on the Tinto-Odiel estuary, SW Spain

This study reports the annual amount of heavy metals discharged by industrial activity into the estuary of the Ría of Huelva (SW Spain). The findings showed that the discharged metals found in highest amounts were Fe (11 t y⁻¹), Zn (3.4 t y⁻¹) and Mo (0.88 t y⁻¹). There were other metals with high pollutant charge, such as Ti (232 kg y⁻¹), As (228 kg y⁻¹), Ni (195 kg y⁻¹), Pb (100 kg y⁻¹), Cr (39 kg y⁻¹) and Cd (33 kg y⁻¹). These results were compared with pollutants transported via the Tinto and Odiel rivers from abandoned mining activities in the Iberian Pyrite Belt (IPB), and it was deduced that the amounts spilled exclusively by industries were less than 1% in relation to the total discharge. Hence, the treatment of residues from the IPB should be the priority goal to improve water quality in the estuary.