Search results for "geographic distribution"
showing 10 items of 37 documents
Is Spain a lumpy country? A dynamic analysis of the ‘lens condition’
2008
We implement the ‘lens condition’ of Deardoff (1994) to investigate whether lumpiness, an excessively uneven geographic distribution of production factors, is large enough to allow for regional specialization of production at different factor prices. Using data from 50 Spanish provinces over the period 1964 to 2001, we show that Spain evolved from being a lumpy economy to a state where lumpiness no longer mattered.
Ammonite extinction and nautilid survival at the end of the Cretaceous
2014
One of the puzzles about the end-Cretaceous extinctions is why some organisms disappeared and others survived. A notable example is the differential extinction of ammonites and survival of nautilids, the two groups of co-occurring, externally shelled cephalopods at the end of the Cretaceous. To investigate the role of geographic distribution in explaining this outcome, we compiled a database of all the occurrences of ammonites and the nautilid genus Eutrephoceras in the last 0.5 m.y. of the Maastrichtian. We also included recently published data on ammonite genera that appear to have briefly survived into the Paleocene. Using two metrics to evaluate the geographic range of each genus (first…
Anatomical Variations in the Sinoatrial Nodal Artery: A Meta-Analysis and Clinical Considerations
2016
Background and Objective The sinoatrial nodal artery (SANa) is a highly variable vessel which supplies blood to the sinoatrial node (SAN). Due to its variability and susceptibility to iatrogenic injury, our study aimed to assess the anatomy of the SANa and determine the prevalence of its anatomical variations. Study Design An extensive search of major electronic databases was performed to identify all articles reporting anatomical data on the SANa. No lower date limit or language restrictions were applied. Anatomical data regarding the artery were extracted and pooled into a meta-analysis. Results Sixty-six studies (n = 21455 hearts) were included in the meta-analysis. The SANa usually aros…
Biogeographic patterns of belemnite body size responses to episodes of environmental crisis
2019
Body size changes have been investigated through episodes of environmental crisis among several groups of organisms but the relative contribution of within-lineage size changes, selective extinction and origination of taxa on these patterns is still being debated. Rapid warming, anoxia, and perturbations of the carbon cycle linked with volcanic activity, as well as their impact on marine diversity are well documented for the Pliensbachian-Toarcian (Pli-Toa) boundary and for the Toarcian Oceanic Anoxic Event (T-OAE). Belemnites were a very abundant and successful cephalopod group in the Mesozoic oceans playing a paramount role in the oceanic trophic webs. Belemnites have mainly been studied …
On two new species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa) from Bransfield Strait (Antarctica)
1998
Two species of the genus Oswaldella Stechow, 1919 new to science (Oswaldella crassa sp. nov. and O.␣curiosa sp. nov.) were studied. Both species are described and figured; their systematic position amongst the remaining species of the genus is discussed. The material originates from the Bransfield Strait area (Antarctica) and was collected during the United States Antarctic Research Program with R.V. Eltanin. A comparative table listing the main features of the known species of Oswaldella is presented. Finally, a general survey of geographical and bathymetrical distribution of the known species of Oswaldella is given.
<p><strong><em>Sinostoma</em> <em>yunnanicum</em>, the first nemastomatine harvestman in China (Arachnida: Opilio…
2016
The easternmost Nemastomatinae species, Sinostoma yunnanicum n. gen., n. sp., from northern Yunnan, China is described. It extends the geographic distribution of Nemastomatinae by roughly 3000 km southeastwards. Within Nemastomatinae Sinostoma displays plesiomorphic characters, including the long, basic bulb of the truncus shaft and the extremely short glans of penis, armed with short robust spines. Sinostoma may represent a relict line in the early evolution of nemastomatine harvestmen.
Two new antarctic species of the genus Schizotricha Allman, 1883 (Cnidaria, Hydrozoa)
1998
Two new antarctic species of the genus Schizotricha Allman have been studied. The material comes from the Scotia Sea (Antarctica) and was collected by the Spanish antarctic expedition `Antartida 8611'. Both species are described and figured and the systematic position is discussed. A general survey of the geographical and bathymetrical distribution of the antarctic and subantarctic species of the genus is given. Finally, a key for the identification of the antarctic and subantarctic species of the genus, together with a comparative table including main features, are presented.
Patterns of male-specific inter-population divergence in Europe, West Asia and North Africa
2000
summary We typed 1801 males from 55 locations for the Y-specific binary markers YAP, DYZ3, SRY "!)$" and the (CA)n microsatellites YCAII and DYS413. Phylogenetic relationships of chromosomes with the same binary haplotype were condensed in seven large one-step networks, which accounted for 95% of all chromosomes. Their coalescence ages were estimated based on microsatellite diversity. The three largest and oldest networks undergo sharp frequency changes in three areas. The more recent network 3‐1A clearly discriminates between Western and Eastern European populations. Pairwise Fst showed an overall increment with increasing geographic distance but with a slope greatly reduced when compared …
Characterization of measles virus strains circulating in Southern Italy (Palermo area, Sicily) between 2010 and 2011
2015
Measles virus (MV) was classified in 24 genotypes that show a distinct geographic distribution. Genotypes contain multiple distinct lineages. In 2011 large outbreaks of measles occurred in Italy and in many European countries. Aims of this study are to analyze the intra-genotype variability and to follow the importation and the spread of new MV strains in Sicily. A fragment of 450. bps of MV C-terminal nucleoprotein was sequenced from sera of 73 Sicilian patients with symptomatic measles infections, occurred between 2010 and 2011. Five MV strains were D4 genotype and 68 were D8 genotype. The MV/D4 sequences were related to MV/D4-Enfield variant. Two lineages of MV/D8 genotypes, related to M…
Taxonomic Identity, Geographic Distribution, and Commercial Exploitation of the Culinary-Medicinal Mushroom Pleurotus nebrodensis (Basidiomycetes)
2016
An updated overview of the outcome of studies conducted on the culinary-medicinal mushroom Pleurotus nebrodensis is presented by placing emphasis on the clarification of the taxonomic identity of P. nebrodensis and other related taxa possessing entirely white to cream basidiomes, which grow in association with different plants of the family Apiaceae. Cultivation techniques, quality of the product sold and sales price, as well as nutritional and medicinal aspects are discussed. Taking also into consideration the high economic importance of P. nebrodensis, it is essential to proceed with the verification of the commercial strains currently available in the international market under the name …