982 resultados para CA-15.3
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Do not confuse with a monograph issued in 1850 with same title proper, also edited by G. Fiorelli: Giornale degli scavi di Pompei : documenti originali. Cf. Furchheim, p. 39 and Palumbo, p. 23.
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Pai qi: "Bu zheng shi si ya men cang ban".
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Oxygen exposure has a large impact on lipid biomarker preservation in surface sediments and may affect the application of organic proxies used for reconstructing past environmental conditions. To determine its effect on long chain alkyl diol and keto-ol based proxies, the distributions of these lipids was studied in nine surface sediments from the Murray Ridge in the Arabian Sea obtained from varying water depths (900 to 3000 m) but in close lateral proximity and, therefore, likely receiving a similar particle flux. Due to substantial differences in bottom water oxygen concentration (<3 to 77 µmol/L) and sedimentation rate, substantial differences exist in the time the biomarker lipids are exposed to oxygen in the sediment. Long chain alkyl diol and keto-ol concentrations in the surface sediments (0-0.5 cm) decreased progressively with increasing oxygen exposure time, suggesting increased oxic degradation. The 1,15-keto-ol/diol ratio (DOXI) increased slightly with oxygen exposure time as diols had apparently slightly higher degradation rates than keto-ols. The ratio of 1,14- vs. 1,13- or 1,15-diols, used as upwelling proxies, did not show substantial changes. However, the C30 1,15-diol exhibited a slightly higher degradation rate than C28 and C30 1,13-diols, and thus the Long chain Diol Index (LDI), used as sea surface temperature proxy, showed a negative correlation with the maximum residence time in the oxic zone of the sediment, resulting in ca. 2-3.5 °C change, when translated to temperature. The UK'37 index did not show significant changes with increasing oxygen exposure. This suggests that oxic degradation may affect temperature reconstructions using the LDI in oxic settings and where oxygen concentrations have varied substantially over time.
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Insects have a much smaller repertoire of voltage-gated calcium (Ca-v) channels than vertebrates. Drosophila melanogaster harbors only a single ortholog of each of the vertebrate Ca(v)1, Ca(v)2, and Ca(v)3 subtypes, although its basal inventory is expanded by alternative splicing and editing of Ca-v channel transcripts. Nevertheless, there appears to be little functional plasticity within this limited panel of insect Ca-v channels, since severe loss-of-function mutations in genes encoding the pore-forming a, subunits in Drosophila are embryonic lethal. Since the primary role of spider venom is to paralyze or kill insect prey, it is not surprising that most, if not all, spider venoms contain peptides that potently modify the activity of these functionally critical insect Ca-v channels. Unfortunately, it has proven difficult to determine the precise ion channel subtypes recognized by these peptide toxins since insect Ca-v channels have significantly different pharmacology to their vertebrate counterparts, and cloned insect Ca-v channels are not available for electrophysiological studies. However, biochemical and genetic studies indicate that some of these spider toxins might ultimately become the defining pharmacology for certain subtypes of insect Ca-v channels. This review focuses on peptidic spider toxins that specifically target insect Ca-v channels. In addition to providing novel molecular tools for ion channel characterization, some of these toxins are being used as leads to develop new methods for controlling insect pests. (c) 2006 Elsevier Ltd. All rights reserved.
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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.
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Background: Obstructive airway diseases (OADs) are among the leading causes of morbidity and mortality worldwide. Shortness of breath (SOB) is the main symptom associated with OADs. International guidelines from the Global Initiative for Chronic Lung Disease (GOLD) and the Global Initiative for Asthma (GINA) have recommended spirometry as an indispensable tool for the diagnosis of asthma and chronic obstructive pulmonary diseases (COPD), but spirometry is rarely used in family practice. Simple and reliable diagnostic tools are necessary for screening community patients with onset of OADs for timely management. Purpose: This thesis examined screening utility of the PiKo-6 forced expiratory volume in one second (pFEV₁) , in six second (pFEV₆), and the pRatio ( pFEV₁/pFEV₆) in SOB patients for OADs in community pharmacy settings. FEV₆ has recently been suggested an excellent surrogate for Forced Vital Capacity (FVC), which requires maximum exhalation of the lungs. Methods: Patients with SOB symptoms who were prescribed pulmonary inhalers, by their family physicians, were recruited via community pharmacies. Trained pharmacists collected two PiKo-6 tests to assess the repeatability of the PiKo-6 device. All patients performed laboratory spirometry ( FEV₁, FVC and FEV₁/FVC) to obtain physician diagnosis of their OADs. The results of the PiKo-6 spirometer and laboratory spirometer were compared. In addition, the PiKo-6 pRatio and laboratory FEV₁/FVC were assessed against physician diagnosed COPD. Results: Sixty three patients volunteered to perform the PiKo-6 spirometry. Of these, 52.4 % were men (age 53.9 ± 15.3 years; BMI 31.9 ± 7.40 kg/m2). Repeated testing with pFEV₁, pFEV6 and pRatio correlated significantly (within correlation, r = 0.835, p-Value≤ 0.05 ; 0.872, p- Value≤ 0.05; and 0.664, p-Value≤ 0.05). In addition, pFEV₁, pFEV6 and pRatio correlated significantly with FEV₁, FVC and FEV₁/FVC, respectively (between correlation = 0.630, p- Value≤ 0.05 ; 0.660, p-Value≤ 0.05 and 0.580, p-Value≤ 0.05). The cut-off value corresponding to the greatest sum of sensitivity and specificity of pRatio for physician-diagnosed COPD was <0.80, the sensitivity and specificity were 84 % and 50%, respectively. Conclusions The portable PiKo-6 correlates moderately well with the standard spirometry, when delivered by community pharmacists to patients with OADs. The PiKo-6 spirometer may play a role in screening patients suspected of having an OAD in community pharmacies that may benefit from early physician diagnosis and appropriate management.
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An exceptional triple palynological signal (unusually high abundance of marine, freshwater, and terrestrial palynomorphs) recovered from a core collected during the 2007 ANDRILL (Antarctic geologic drilling program) campaign in the Ross Sea, Antarctica, provides constraints for the Middle Miocene Climatic Optimum. Compared to elsewhere in the core, this signal comprises a 2000-fold increase in two species of dinoflagellate cysts, a synchronous five-fold increase in freshwater algae, and up to an 80-fold increase in terrestrial pollen, including a proliferation of woody plants. Together, these shifts in the palynological assemblages ca. 15.7 Ma ago represent a relatively short period of time during which Antarctica became abruptly much warmer. Land temperatures reached 10 °C (January mean), estimated annual sea-surface temperatures ranged from 0 to 11.5 °C, and increased freshwater input lowered the salinity during a short period of sea-ice reduction.
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The Late Weichselian-Early Holocene variability of the North Atlantic Current has been studied with focus on the zonal component of this meridional transport during the transition from glacial to interglacial conditions. The investigated sediment core is from 409 m water depth in the SW Barents Sea. Eight Accelerator mass spectrometry (AMS) 14C dates show that the core covers the last 20,000 cal yr B.P. with a centennial scale resolution during Late Weichselian-Early Holocene. Planktic foraminiferal assemblages were analyzed using the >100 ?m size fraction and foraminiferal planktic and benthic d13C and d18O isotopes were measured. Furthermore, a range of physical and chemical analyses has been carried out on the bulk sediment samples. Four time periods have been identified which represent the varying oceanographic conditions in Ingøydjupet, a glacial trough located off the north coast of Norway in the SW Barents Sea. 1) The late glacial (before ca 15,000 cal yr B.P.) influenced by the nearby ice sheets with high amounts of sea ice- or iceberg-transported detritus. 2) The late Oldest Dryas stadial and the Bølling-Allerød interstadial (ca 15,000-12,700 cal yr B.P.) with cold surface water conditions influenced by the collapse of the nearby ice sheets, high amounts of sea ice- or iceberg-transported detritus and melt water and weak subsurface inflow of Atlantic Water. 3) The Younger Dryas cold stadial (12,700-11,650 cal yr B.P.) with low primary productivity and extensive sea ice cover and 4) The Preboreal and Early Holocene (11,650-6800 cal yr B.P. cal yr B.P.) with strong influx of Atlantic Water into the area, near absence of ice rafted debris and generally ameliorated conditions in both surface and bottom water masses as seen from a high flux of foraminifera and increased marine primary production.
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Data on glacial erosion have been compiled and synthesised using a wide range of sediment budget and sediment yield studies from the Svalbard-Barents Sea region. The data include studies ranging in timescale from 1 to 10**6 yr, and in size of drainage basin from 101 to 105 km**2. They show a clear dependence of sediment yield on the mode of glacierization. Polar glaciers erode at rates comparable to those found in Arctic fluvial basins, or about 40 t/km**-2/ yr or 0.02 mm/yr. In contrast, rates of erosion by polythermal glaciers are 800-1000 t/km**2/ yr (or ca 0.3-0.4 mm/yr), while rates from fast-flowing glaciers are slightly more than twice this: 2100 t/km**2/yr (or 1 mm/yr). Similar rates are also found for large glacierized basins like those in the southwestern parts of the Barents Sea. In contrast to the situation in fluvial basins, in which sediment yield typically decreases with increasing basin size, the tendency in glacierized basins is for erosion to be independent of basin size. In studies of sediment yield from glaciers it is sometimes difficult to distinguish between material actually dislodged from the bedrock by glaciers and material dislodged by other processes in interglacial times and simply transported to a depocenter by a glacier. Our data suggest that pulses of sediment resulting from advance of a glacier over previously-dislodged material last on the order of 10**3 yr, and result in inferred erosion rates that are approximately 25% higher than long-term average rates of glacial erosion. The maximum sediment fluxes from the large Storfjorden and Bear Island drainage basins occurred in mid-Pleistocene. The onset of this period of high sediment yield coincided with the onset of the 100 kyr glacial cycle. We presume that this was the beginning of a period of increased glacial activity, but one in which glaciers still advanced and retreated frequently. During the last two to four 100 kyr cycles, however, sediment yields appear to have decreased. This decrease may be the result of the submergence of the Barents Sea. Glacier erosion would be much higher for a subaerial Barents Sea setting than it would be for a present day subsea Barents Sea. A classical question in Quaternary Geology is whether glaciers are more erosive than rivers. We surmise that if factors such as the lithology and the available potential energy (mgh) of the precipitation falling at a given altitude, whether in liquid or solid form, are held constant, then glaciers are vastly more effective agents of erosion than rivers.
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The last glacial-interglacial transition or Termination I (T I) is well documented in the Black Sea, whereas little is known about climate and environmental dynamics during the penultimate Termination (T II). Here we present a multi-proxy study based on a sediment core from the SE Black Sea covering the penultimate glacial and almost the entire Eemian interglacial (133.5 ±0.7-122.5 ±1.7 ka BP). Proxies comprise ice-rafted debris (IRD), O and Sr isotopes as well as Sr/Ca, Mg/Ca, and U/Ca ratios of benthic ostracods, organic and inorganic sediment geochemistry, as well as TEX86 and UK'37derived water temperatures. The ending penultimate glacial (MIS 6, 133.5 to 129.9 ±0.7 ka BP) is characterised by mean annual lake surface temperatures of about 9°C as estimated from the TEX86 palaeothermometer. This period is impacted by two Black Sea melt water pulses (BSWP-II-1 and 2) as indicated by very low Sr/Ca ostracods but high sedimentary K/Al values. Anomalously high radiogenic 87Sr/86Sr ostracod values (max. 0.70945) during BSWP-II-2 suggest a potential Himalayan source communicated via the Caspian Sea. The T II warming started at 129.9 ±0.7 ka BP, witnessed by abrupt disappearance of IRD, increasing d18O ostracod values, and a first TEX86 derived temperature rise of about 2.5°C. A second, abrupt warming step to ca. 15.5°C as the prelude of the Eemian warm period is documented at 128.3 ka BP. The Mediterranean-Black Sea reconnection most likely occurred at 128.1 ±0.7 ka BP as demonstrated by increasing Sr/Ca ostracods and U/Ca ostracods values. The disappearance of ostracods and TOC contents >2% document the onset of Eemian sapropel formation at 127.6 ka BP. During sapropel formation, TEX86 temperatures dropped and stabilised at around 9°C, while UK'37 temperatures remain on average 17°C. This difference is possibly caused by a habitat shift of Thaumarchaeota communities from surface towards nutrient-rich deeper and colder waters located above the gradually establishing halo-and redoxcline.
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Sediment drifts on the continental rise are located proximal to the western side of the Antarctic Peninsula and recorded changes in glacial volume and thermal regime over the last ca. 15 m.y. At Ocean Drilling Program (ODP) Site 1101 (Leg 178), which recovered sediments back to 3.1 Ma, glacial-interglacial cyclicity was identified based on the biogenic component and sedimentary structures observed in X-radiographs, magnetic susceptibility and lithofacies descriptions. Glacial intervals are dominated by fine-grained laminated mud and interglacial units consist of bioturbated muds enriched in biogenic components. From 2.2 to 0.76 Ma, planktonic foraminifera and calcareous nannofossils dominate in the interglacials suggesting a shift of the Antarctic Polar Front (APF) to the south near the drifts. Prior to 2.2 Ma, cyclicity cannot be identified and diatoms dominate the biogenic component and high percent opal suggests warmer conditions south of the APF and reduced sea ice over the drifts. Analyses of the coarse-grained terrigenous fraction (pebbles and coarse sand) from Sites 1096 and 1101 record glaciers at sea-level releasing iceberg-rafted debris (IRD) throughout the last 3.1 m.y. Analyses of quartz sand grains in IRD with the scanning electron microscope (SEM) show an abrupt change in the frequency of occurrence of microtextures at ~1.35 Ma. During the Late Pliocene to Early Pleistocene, the population of quartz grains included completely weathered grains and a low frequency of crushing and abrasion, suggesting that glaciers were small and did not inundate the topography. Debris shed from mountain peaks was transported supraglacially or englacially allowing weathered grains to pass through the glacier unmodified. During glacial periods from 1.35-0.76 Ma, glaciers expanded in size. The IRD flux was very high and dropstones have diverse lithologies. Conditions resembling those at the Last Glacial Maximum (LGM) have been episodically present on the Antarctic Peninsula since ~0.76 Ma. Quartz sand grains show high relief, fracture and abrasion common under thick ice and the IRD flux is low with a more restricted range of dropstone lithologies.