Indigenous amino acids in primitive CR meteorites

Abstract— –CR chondrites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites. Three CRs, Elephant Moraine (EET) 92042, Graves Nunataks (GRA) 95229, and Grosvenor Mountains (GRO) 95577, were analyzed for their amino acid content using high‐performance liquid chromatography with UV fluorescence detection (HPLC‐FD) and gas chromatography–mass spectrometry (GC‐MS). Our data show that EET 92042 and GRA 95229 are the most amino acid–rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 ppm to 249 ppm. The most abundant amino acids present in the EET 92042 and GRA 95229 meteorites are the α‐amino acids glycine, isovaline, α‐aminoisobutyric acid (α‐AIB), and alanine, with δ¹³C values ranging from +31.6‰ to +50.5‰. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly indicate an extraterrestrial origin for these compounds. Compared to Elephant Moraine (EET) 92042 and GRA 95229, the more aqueously altered GRO 95577 is depleted in amino acids. In both CRs and CMs, the absolute amino acid abundances appear to be related to the degree of aqueous alteration in their parent bodies. In addition, the relative abundances of α‐AIB and β‐alanine in the Antarctic CRs also appear to depend on the degree of aqueous alteration.     

Heliospheric Observations of STEREO-Directed Coronal Mass Ejections in 2008?–?2010: Lessons for Future Observations of Earth-Directed CMEs

We present a study of coronal mass ejections (CMEs) which impacted one of the STEREO spacecraft between January 2008 and early 2010. We focus our study on 20 CMEs which were observed remotely by the Heliospheric Imagers (HIs) onboard the other STEREO spacecraft up to large heliocentric distances. We compare the predictions of the Fixed-?? and Harmonic Mean (HM) fitting methods, which only differ by the assumed geometry of the CME. It is possible to use these techniques to determine from remote-sensing observations the CME direction of propagation, arrival time and final speed which are compared to in-situ measurements. We find evidence that for large viewing angles, the HM fitting method predicts the CME direction better. However, this may be due to the fact that only wide CMEs can be successfully observed when the CME propagates more than 100^° from the observing spacecraft. Overall eight CMEs, originating from behind the limb as seen by one of the STEREO spacecraft can be tracked and their arrival time at the other STEREO spacecraft can be successfully predicted. This includes CMEs, such as the events on 4 December 2009 and 9 April 2010, which were viewed 130^° away from their direction of propagation. Therefore, we predict that some Earth-directed CMEs will be observed by the HIs until early 2013, when the separation between Earth and one of the STEREO spacecraft will be similar to the separation of the two STEREO spacecraft in 2009??C?2010.     

A site evaluation campaign for a ground based atmospheric Cherenkov telescope in Romania

Around the world, several scientific projects share the interest of a global network of small Cherenkov telescopes for monitoring observations of the brightest blazars??the DWARF network. A small, ground based, imaging atmospheric Cherenkov telescope of last generation is intended to be installed and operated in Romania as a component of the DWARF network. To prepare the construction of the observatory, two support projects have been initiated. Within the framework of these projects, we have assessed a number of possible sites where to settle the observatory. In this paper we submit a brief report on the general characteristics of the best four sites selected after the local infrastructure, the nearby facilities and the social impact criteria have been applied.     

An analysis of the causes of decadal variations of rainfall in Shandong in summer

The precipitation in Shandong in July, August as well as the whole summer (JJA) and the corresponding 500hPa geopotential height fields are analyzed by means of the SVD (singular value decomposition) methodology. It is found that the general circulations in East Asia and the Western Pacific underwent decadal changes around 1979. The geopotential height, in particular over key areas like the South China Sea and the Philippines, increased after 1979. Corresponding to the changes in the geopotential height, the rainfall in Shandong started to decrease around 1979. The synthesized analysis shows that when the geopotential height at 500hPa level decreases in the key areas, the Western Pacific subtropical high shifts northward and an anticyclonic anomalous cell enforces the southerly flow over Shandong-Korea-Japan, Shandong could experience a wet period. A dry period is likely to occur when the geopotential height increases in these key areas, the subtropical high moves southward or expands westward to a great distance, and a cyclonic anomalous cell controls Shandong. Respective conceptual models for the causative mechanism are obtained for the cases of July, August and the whole summer (JJA).     

区域视觉形象识别系统设计的理论与实践

目前，全国各地正在兴起区域形象设计与建设的浪潮，但如何把区域形象信息系统地传递出去，这方面的理论研究大大落后于实践。文章就区域形象信息传递的有效工具－区域视觉识别系统设计的主要内容，设计的原则，设计的基本流程等在理论与实践上作了较为详细的探讨，并就区域视觉识别系统设计方案的经济学论证作了一些有益探讨。     

Linear mechanism of generation and intencification of internal gravity waves in the ionosphere at their interaction with a nonuniform zonal wind: 1. Model of the medium and initial dynamic equations

The specific features of the generation and intensification of internal gravity wave structures in different atmospheric-ionospheric regions, caused by zonal local nonuniform winds (shear flows), are studied. The model of the medium has been explained and an initial closed system of equations has been obtained in order to study the linear and nonlinear dynamics of internal gravity waves (IGWs) when they interact with the geomagnetic field in a dissipative ionosphere (for the D, E, and F regions).     

Climatic variability in the Late Copper Age: stable isotope fluctuation of prehistoric Unio pictorum (Unionidae) shells from Lake Balaton (Hungary)

Geochemical records of bivalve shells have been increasingly studied in the last decade to obtain information on climate conditions. In this paper we present stable isotope compositions of living and prehistoric shells of freshwater mussels (Unionidae) and their relationships with climate conditions in a shallow lake environment of Lake Balaton, West-Central Hungary. Physical conditions and stable oxygen isotope compositions of lake water samples were monitored where living bivalves were collected. Comparisons between seasonal variations in ambient temperature, water composition and within-shell isotopic variations indicate that the shells of Unio pictorum do reflect local changes at high resolution and thus can be used to study past conditions. Additionally, shells covering the last two decades were gathered at several locations along the lake in order to determine spatial and temporal variations in the shells’ isotopic compositions as a function of weather conditions. As an application, prehistoric shells collected in archaeological excavations were analysed in order to study past environmental variations. Climate variations during the Late Copper Age (5460–4870 cal. yr BP) have been assumed on the basis of geomorphological and archaeozoological observations at the site Balatonkeresztúr-Réti-dűlő (south of Lake Balaton), that suggested increasing humidity as a cause of changes in settlement location and domestic livestock husbandry. Stable carbon and oxygen isotope compositions of prehistoric bivalve shells were analyzed from excavations representing five archaeological subphases (Boleráz subphase, 5460–5310 cal. yr BP; two transitional subphases around 5310 cal. yr BP; Early Classic subphase, 5310–5060 cal. yr BP; Late Classic subphase, 5040–4870 cal. yr BP). The analyses revealed significant negative C and O isotope shifts in the transitional subphases relative to the earlier and later subphases. The isotopic variations indicate that the local climate became relatively wet and possibly cold around 5310 cal. yr BP, then it returned to drier (and likely warmer) conditions during the Classic subphases. This interpretation is in agreement with previous studies on climate changes related to the “5.3 ky event” in the European continental area and the North Atlantic Region, indicating an Atlantic influence in the Carpathian Basin.     

Limnic Responses to Increased Effective Humidity during the 8200 cal. yr BP Cooling Event in Southern Sweden

Highly resolved sediment stratigraphic and stable isotope records from a lake in south-central Sweden give evidence of relatively humid summers during the wide-spread cold event at c. 8200 cal. BP. A transient lake-level rise led to increased catchment erosion followed by enhanced phytoplankton production and disturbance of the Chara-dominated algal community. An associated increase in the deposition of organic material resulted in hypolimnetic oxygen deficit and methane formation as inferred from elevated sulphur content of the sediments and strong depletion in ¹³C of bulk organic material. In combination with dry and cold winter conditions as revealed by other proxy records, these data suggest the development of a strongly seasonal climate in northwestern Europe in response to altered atmospheric circulation at this stage. Enhanced zonal circulation with frequent cyclonic activity and increased effective humidity probably characterized the summer climate of southern and central Scandinavia, consistent with conditions inferred for continental Europe. In contrast, the winter climate was dominated by blocking high-pressure circulation, giving rise to cold and dry conditions.     

Relationships between Holocene sea-level variations,trophic development,and climatic change in Negra Lagoon,Southern Uruguay

Paleolimnological data are presented on trophic development, climatic change and sea level variations in Negra Lagoon, a 142 km² coastal lagoon in southern Uruguay. Using a sediment core that extended to the early Holocene, analyses of organic matter, carbonate, diatoms and opal phytoliths allowed us to track changes in trophic state and paleosalinity levels, which were closely related to Holocene sea level variation, temperature and humidity. Diatom Association Zones (DAZ) corresponding to transgressive events were dominated by marine/brackish taxa and relatively low organic matter values, while those DAZ corresponding to regressive events showed increases in brackish/freshwater diatoms and organic matter. Opal Phytoliths Association Zones (OPAZ) also were identified, temperature and humidity indices were calculated, and climatic trends were inferred. During the middle Holocene (i.e., ~5000–4000 yr BP), cool–dry climatic conditions were established. After ~4000 yr BP, a transition from cool to warm–humid conditions was observed, but fully warm humid conditions established only after ~1700 yr BP. Such climatic amelioration led to increases in trophic state.