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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 874-875 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Rat procathepsin B has been expressed in the yeast Pichia pastoris. To facilitate crystallization of the proform two mutations were introduced: Cys29Ser to avoid self-processing and Ser115Ala to eliminate an N-glycosylation site. The recombinant protein was purified and crystallized by vapor diffusion against mother liquor containing 100 mM KSCN, 100 mM phosphate buffer, pH 6.5 and polyethylene glycol (PEG) 3350 as a precipitating agent. Crystal size was increased by multiple macroseeding. At a 16% PEG concentration trigonal crystals were obtained, with the space group P3121 and a = 99.6, c = 141.4 Å, γ = 120°. They diffract to 2.8 Å resolution using a rotating-anode source. At a concentration of 11% PEG, rod-shaped crystals were grown. They are monoclinic, space group P21, a = 62.8, b = 67.9, c = 100.4 Å, β = 98.2° and diffract to approximately 3.5 Å.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2011-01-26
    Description: A mid- to late-Holocene synthesis of fire activity from the Mediterranean basin explores the linkages among fire, climate variability and seasonality through several climatic and ecological transitions. Regional fire histories were created from 36 radiocarbon-dated sedimentary charcoal records, available from the Global Charcoal Database. During the mid-Holocene ‘Thermal Maximum’ around 7500—4500 cal. BP, charcoal records from the northern Mediterranean suggest an increase in fire while records from the southern Mediterranean indicate a decrease associated with wetter-than-present summers. A North—South partition between 40° and 43°N latitude is apparent in the central and western Mediterranean. Relatively abrupt changes in fire activity are observed c . 5500—5000 cal. BP. Records of Holocene fire activity appear sensitive to both orbitally forced climate changes and shorter-lived excursions which may be related to North Atlantic cold events, possibly modulated by an NAO-like climate mechanism. In cases where human—fire interactions have been documented, the regional coherency between fire occurrence and climate forcing suggests a dominant fire—climate relationship during the early—mid Holocene. The human influence on regional fire activity became increasingly important after c . 4000—3000 cal. BP. Results also suggest that: (1) teleconnections between the Mediterranean area and other climatic regions, in particular the North Atlantic and the low latitudes monsoon areas, influenced past fire activity; (2) gradual forcing, such as changes in orbital parameters, may have triggered abrupt shifts in fire activity; (3) regional fire reconstructions contradict former notions of a gradual (mid- to late-Holocene) aridification of the entire region due to climate and/or human activities and the importance of shorter-term events; (4) Mediterranean fire activity appears hightly sensitive to climate dynamics and thus could be considerably impacted by future climate changes.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 3
    Publication Date: 2011-01-26
    Description: We present a synthesis of geological, stratigraphic, geomorphological and stable isotope data collected from continental archives to highlight the environmental and climatic differences between the first and second half of the Holocene of central and southern Italy. The beginning of the Holocene is marked by rapid environmental change. In Mediterranean Italy, between c . 9500 cal. BP and c . 6000—5500 cal. BP, average temperatures were probably higher and environmental conditions were generally stable; between c . 9000 and 7000 cal. BP, meteoric precipitation was at its highest. The end of the wetter period seems to occur later, at c . 6000—5000 cal. BP. Since c . 6000—5000 cal. BP, rapid climatic excursions are apparent in different palaeoclimate proxies, with both variability in meteoric precipitation and temperature evident. Of particular relevance is the event occurring at c . 4200 cal. BP. This event heralds a period of significant environmental change in the Apennines and, more generally, in central Italy. Following this event, environmental variability appears most pronounced and frequent. Some environmental changes during the early Holocene and after 4200 cal. BP seem to be in phase with IRD events in the North Atlantic, which suggest: (1) teleconnections between North Atlantic and Mediterranean areas; and (2) a possible influence of North Atlantic meridional overturning circulation in controlling the advection of moisture over the central Mediterranean basin via westerly air masses. The archives used in this review allow us to consider climate evolution as a driver of most of the observed environmental changes.
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    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
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  • 4
    Publication Date: 2011-01-26
    Description: This study presents pollen-based climate reconstructions of Holocene temperature and precipitation seasonality for two high-resolution pollen sequences from the central (Lake Accesa, central Italy) and eastern Mediterranean (Tenaghi Philippon, Greece) regions. The quantitative climate reconstruction uses multiple methods to provide an improved assessment of the uncertainties involved in palaeoclimate reconstructions. The multimethod approach comprises Partial Least Squares regression, Weighted Average Partial Least Squares regression, the Modern Analogues Technique, and the Non-Metric-Multidimensional Scaling/Generalized Additive Model method. We find two distinct climate intervals during the Holocene. The first is a moist period from 9500 to 7800 cal. BP characterised by wet winters and dry summers, resulting in a strongly seasonal hydrological contrast (stronger than today) that is interrupted by a short-lived event around 8200 cal. BP. This event is characterised by wet winters and summers at Accesa whereas at Tenaghi Philippon the signal is stronger, reversing the established seasonal pattern, with dry winters and wet summers. The second interval represents a later aridification phase, with a reduced seasonal contrast and lower overall precipitation, lasting from 7800 to 5000 cal. BP. Present-day Mediterranean conditions were established between 2500 and 2000 cal. BP. Many studies show the Holocene to have a complex pattern of climatic change across the Mediterranean regions. Our results confirm the traditional understanding of an evolution from wetter (early Holocene) to drier climatic conditions (late Holocene), but highlight the role of changing seasonality during this time. Our data yield new insights into the aspect of seasonality changes, and explain the apparent discrepancies between the previously available climate information based on pollen, lake-levels and isotopes by invoking changes in precipitation seasonality.
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    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
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  • 5
    Publication Date: 2014-04-12
    Description: This paper investigates the relative influences of climatic and anthropogenic factors in explaining environmental and societal changes in the southern Alps, Italy. We investigate a deep sediment core (LL081) from Lake Ledro (652 m a.s.l.). Environmental changes are reconstructed through multiproxy analysis, that is, pollen-based vegetation and climate reconstruction, magnetic susceptibility (MS), lake level, and flood frequency, and the paper focuses on the climate and land-use changes which occurred during the late Holocene. For this time interval, Lake Ledro records high mean water table, increasing amount of pollen-based precipitation, and more erosive conditions. Therefore, while a more humid late Holocene in the southern Alps has the potential to reinforce the forest presence, pollen evidence suggests that anthropogenic activities changed the impact of this regional scenario. Land-use activity (forest clearance for pastoralism, farming, and arboriculture) opened up the large vegetated slopes in the catchment of Lake Ledro, which in turn magnified the erosion related to the change in the precipitation pattern. The record of an almost continuous human occupation for the last 4100 cal. BP is divided into several land-use phases. On the one hand, forest redevelopments on abandoned or less cultivated areas appear to be climatically induced as they occurred in relation with well-known events such as the 2.8-kyr cold event and the ‘Little Ice Age’. On the other hand, climatically independent changes in land use or habitat modes are observed, such as the late-Bronze-Age lake-dwellings abandonment, the human population migration at c . 1600 cal. BP, and the period of the Black Death and famines at 600 cal. BP.
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    Topics: Geography , Geosciences
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  • 6
    Publication Date: 2013-07-06
    Description: Bleicher (2013) discussed interpretations proposed by Magny (2004) that Holocene lake-level fluctuations in west-central Europe suggest possible solar forcing of climate. He pointed out that the method used by Magny (2004) is a variant of a cumulative probability function (CPF) and cannot prove solar forcing of central European lake-level changes. He concluded that only few episodes of lake-level changes are climatically driven and that non-climatic factors were dominating. While Bleicher’s paper offers a stimulating contribution to the general debate on CPFs, the present comment is based on an approach which, in contrast to CPFs, excludes any consideration of variations in the probabilities over the time intervals given by calibration of 14 C dates, as well as any distinction between types of dates (radiocarbon versus tree ring). It produces a revised pattern of the mid-European high lake-level events for the whole Holocene, supporting the hypothesis proposed in Magny (2004). Comparisons with other regional and North Atlantic palaeoclimatic records suggest that, without excluding other forcing factors, the successive high lake-level events recognised in west-central Europe reflect a combination of three main forcing factors acting on millennial and centennial scales, i.e. orbitally driven changes in insolation, impacts of deglacial outbursts and, possibly, variations in solar activity. Finally, it is clear that further investigations are still needed in order to improve the chronological data set for mid-European lake-level fluctuations, with particular attention to better defining the beginning and end of events.
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    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
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  • 7
    Publication Date: 2012-12-21
    Description: A multiproxy approach to a sediment sequence at Lake Saint-Point in the French Jura Mountains gives evidence of a strong coupling between changes in terrestrial and lacustrine ecosystems throughout the Holocene. The early Holocene (11,700–10,200 cal. BP) is characterised by the recovery of terrestrial and lake ecosystems favoured by climatic warming. During the middle Holocene (10,600–6200 cal. BP), the climatic optimum coincided with an extension of deciduous forests into the catchment area, while lake sedimentation is dominated by authigenic carbonates and low detrital inputs. After 6200 cal. BP, the Neoglacial favoured expansion of Abies-Fagus forests and increasing detrital inputs to the lake where ostracod fauna declined and changed in composition. After 1200 cal. BP, human impact was responsible for extensive forest clearings in the catchment area, while the lake basin shows contrasting pictures with increasing detrital input, resuming sedimentation of authigenic carbonates and changes in dominant ostracod species. Orbitally driven climatic variations were the dominant factor of environmental changes until c . 1200 cal. BP. Around 2600 cal. BP, human impact increased and became the major factor in the catchment area and the lake basin from 1200 cal. BP onwards. Finally, the Saint-Point record offers a clear illustration of how gradual changes in insolation or increasing human impact may provoke, even under temperate climatic conditions, abrupt responses in mid-European terrestrial and lake ecosystems, and how differences in the dates of tipping points revealed by proxies suggest specific threshold values depending on the sensitivity of indicators used and on their role in the different compartments of these ecosystems.
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    Topics: Geography , Geosciences
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  • 8
  • 9
    Publication Date: 2008-02-01
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
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  • 10
    Publication Date: 2011-01-25
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage Publications
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