The R Coronae Borealis Connection

The R Coronae Borealis (RCB) stars are rare hydrogen-deficient carbon-rich supergiants which undergo spectaculardeclines in brightness of up to 8 magnitudes at irregular intervals as dust forms along the line of sight.Understanding the RCB stars is a key test for any theory whichaims to explain hydrogen deficiency in post-Asymptotic Giant Branch (AGB) stars. There are two major evolutionary models for the origin of RCB stars: the Double Degenerate and the Final Helium ShellFlash. In the final flashmodel, there is a close relationship between RCB stars and Planetary Nebulae (PNe). The connection between RCB stars and PNe has recentlybecome stronger, since the central stars of three old PNe (Sakurai's Object, V605 Aql and FG Sge) have had observedoutbursts that transformed them from hot evolved central stars into cool giants with the spectral properties of an RCB star.     

A Validation of CloudSat and CALIPSO's Temperature,Humidity, Cloud Detection,and Cloud Base Height over the Arctic Marine Cryosphere

Abstract

This study presents a semi‐analytic non‐iterative solution for the Monin‐Obukhov similarity equations under unstable surface conditions. The solution is represented in terms of the non‐dimensional Monin‐Obukhov stability parameter z/L. This parameter is given as a function of the bulk Richardson number and other surface parameters including the heat and momentum roughness lengths which are generally assumed to be different in this formulation. The proposed formulations give results that are both quantitatively and qualitatively consistent with the fully iterated numerical solution for a wide range of surface parameters.     

CHILDREN'S PERCEPTION OF A DOWNTOWN SHOPPING CENTER

This paper offers an exploratory investigation of the effects of a child's age on three behavioral constructs (awareness space, activity space, and attitude) concerning a downtown shopping center in Bristol, England. The data are elicited from three samples of Bristol school children defined according to age and are analyzed using statistical inferential procedures. The results disclose that awareness space and activity space consistently increase with age. In addition, attitudinal responses to specific features of the shopping center exhibit a gradual change over a long-term period.     

Late Quaternary glaciation of the Cordillera Real,Bolivia

Glacial geological studies in tropical mountain areas of the Southern Hemisphere can be used to address two issues of late Pleistocene climate change: the global synchroneity of deglaciation and the magnitude of temperature reduction in the tropics. Radiocarbon dates from the Cordillera Real and from other areas in Perú and Bolivia suggest that late Pleistocene glaciation culminated between 14 000 and 12 000 yr BP, followed by rapid deglaciation. Because deglaciation was apparently synchronous with that in Northern Hemisphere regions, insolation change at high latitudes may not have been the only factor that produced global deglaciation at this time. Late Pleistocene glaciation in the Cordillera Real culminated when precipitation was 200 mm yr^?1 higher and temperatures were 3.5° ±1.6°C lower than today; this produced an equilibrium-line altitude depression of about 300 ± 100 m on the western side of the cordillera. Prior to this, conditions were drier and probably at least as cold. However, the lack of moraines in the Cordillera Real dated to the Last Glacial Maximum (ca. 18000 yr BP) precludes using the equilibrium-line altitude method to quantitatively evaluate the discrepancy between warm sea-surface temperatures and cold terrestrial conditions reconstructed with other proxies for this time period.     

A Late Weichselian stable isotope stratigraphy compared with biostratigraphical data: A case study from southern Sweden

Late Weichselian lake sediments from a site in southern Sweden, were analysed for stable carbon and oxygen isotopes, as well as plant macrofossils and insect remains. By comparison of independent data sets, general climatic changes were demonstrated. Lithological, chemical and stable isotope data reveal two significant climatic oscillations at ca. 12 200–12 000 and ca. 11 000–10 200 yr BP respectively. Continental climatic conditions, indicated by evaporative enrichment of ¹⁸O in lake marl, characterise parts of the early lake history, including the Older Dryas Stadial. Distinct variations of δ¹³C in organic material is discussed in terms of climatically induced changes in lake-water chemistry. Different types of photosynthetic assimilation of dissolved inorganic carbon is proposed as a contributing factor influencing lake marl δ¹³C. The universal application of a positive correlation between lake marl δ¹⁸O and mean annual air temperature is questioned. Quantifications of mean summer and winter temperatures based on beetle analysis show a climatic optimum around 12 000 yr BP, a marked cooling around 11 000 yr BP and a strong amelioration at ca. 10 200 yr BP. These climatic events were accompanied by distinct changes in aquatic vegetation. Plant macrofossil and insect analyses indicate an open vegetation during the entire period studied. Biostratigraphical data reflecting local limnic and terrestrial vegetation and regional climate facilitate the interpretation of stable isotope data.     

Palaeoecology of a late Allerød peat bed at Godøy,western Norway

A peat bed found under solifluction deposits on Godøya island, western Norway, accumulated during a few decades around 11 000 yr BP, at the end of the Allerød period of the Late Weichselian. Palaeoecological investigations showed a local vegetation succession on wet sand culminating in a mire community dominated by Carex nigra. Periodic flooding brought in sand and silt, which decreased as drainage was impeded sufficiently for standing water to develop. The surrounding terrestrial vegetation was dominated by Salix scrub, with some open heath and alpine habitats nearby. Apart from two aquatic species, the 29 insect taxa recorded are characteristic of alpine heaths, plant litter (under Salix scrub) and stream-sides. Their remains, together with the terrestrial plant macrofossils, were washed into the mire from nearby. Because the fossils are locally derived, the environmental reconstructions are of the actual conditions at Godøy at ca. 11 000 yr BP. Palaeotemperature estimates from beetles and plants are in agreement. The coleopteran estimates (Mutual Climatic Range Method) suggest mean July temperatures of 10–13°C, slightly cooler than today (13.5°), and January temperatures between +1 and ?10°C, similar to or much colder than today. Summer temperature estimates from individual plant taxa indicate that temperatures during the Allerød period were similar to today's, but estimates from the reconstructed vegetation and timber-line positions give estimates up to 3.5° cooler. Temperatures fell 2.5–7.5°C at the Younger Dryas. This abrupt and severe cooling initiated the solifluction processes on Godøya that buried the peat. The Godøy peat bed and its contained fossils provide a rare glimpse of Allerød biota and environments at the local (site) scale.