Search results for "Category"

Assessing, measuring and modelling erosion in calanchi areas: A review

2016

Calanchi are erosion landforms characterised by a heavily dissected terrain with steep, unvegetated slopes and channels with a dendritic pattern, which rapidly incise and extend headwards. Recent literature focusing on badland systems highlights their similarity with other larger fluvial landforms, stating that these behave as a full size laboratory, due to their rapid development in space and time and to the diversity of geomorphic processes involved. In this paper, a brief review of the most important results on badland research is firstly presented. Then, the morphometric similarity between calanchi and other erosion landforms is discussed. Finally, models quantitatively relating the vol…

Pupils’ mental models of a pulley in balance, and how the models are changed by successive pulley demonstrations

2012

Chromosome numbers in Hieracium and Pilosella species (Asteraceae) from the Iberian Peninsula and the Balearic Islands

2007

Mitotic chromosome numbers are reported from 16 Hieracium and two Pilosella species from the Iberian Peninsula and the Balearic Islands that are little known cytogenetically. The chromosome numbers of Hieracium aragonense Scheele (2 n = 27, 36), H. compositum Lapeyr. (2 n = 27), H. murcandidum G. Mateo (2 n = 27), H. spathulatum Scheele (2 n = 27), H. segurae Mateo (2 n = 27), H. teruelanum Mateo (2 n = 27), H. valentinum Pau (2 n = 27), Pilosella pseudovahlii (De Retz) Mateo (2 n = 18), and P. tardans (Peter) Sojak (2 n = 36) were determined for the first time. New cytotypes were detected in H. cordifolium Lapeyr. (2 n = 27) and H. loscosianum Scheele (2 n = 36). The karyo- type of the stu…

Karyology of Limonium (Plumbaginaceae) species from the Balearic Islands and the western Iberian Peninsula

2007

Somatic chromosome numbers, conventional karyotype features and idiograms are reported for 27 Limonium species inhabiting the Western Mediterranean basin (Iberian Peninsula and the Balearic Islands). The chromosome numbers of Limonium barceloi (2n = 36), L. ejulabilis (2n = 24), L. inexpectans (2n = 26), L. interjectum (2n = 24), and L. scopulorum (2n = 25) were determined for the first time. In addition, new aneuploid and/or polyploid cytotypes are reported in L. alcudianum (2n = 26), L. bonafei (2n = 26), L. camposanum (2n = 26), L. companyonis (2n = 26), L. dufourii (2n = 26), L. geronense (2n = 36), L. marisolii (2n = 54), L. migjornense (2n = 50), and L. pseudodictyocladon (2n = 16). A…

<i>Limonium carvalhoi (Plumbaginaceae)</i>, a new endemic species from the Balearic Islands

1998

ROSSELLO, J.A., L. SAEZ & A.C. CARVALHO (1998). Limonium carvalhoi (Plumbaginaceae), a new endemic species from the Balearic Islands. Anales Jard. Bot. Madrid 56(1): 23-31. Limonium carvalhoi Rossello & L. Saez is described from a single salt marsh locality in southwest Majorca. Morphologically, L. carvalhoi is ciose to L. inexpectans, L. migjornense and L. magallufianum , all Balearic endemics. The new species has an apomictic breeding system and shows a single pollen/stigma combination (B/papillate type). Chromosome number ranges from 2n = 24 to 2n = 26. Based on the occurrence of a long metacentric chromosome in all cells examined, it is suggested that the original chromosome complement …

Dynamics of particulate major and trace elements in the lower reaches of the Daugava River and adjacent area of the Gulf of Riga (Baltic Sea).

2004

Suspended particulate matter (SPM) was collected in the freshwater-seawater mixing zone in the lower reaches of the Daugava River (Latvia) and adjacent marine area, during five cruises in 1998-2001. The study focused on biogeochemical phase exchange processes. SPM in the freshwater was found to be mainly allochthonous with a high content of organic matter, Mn and sorbed phosphate. Property-salinity plots suggested flocculation of humic-Fe complexes across the salinity gradient. The variability of sorbed phosphate was related to particulate Fe, although no dependence on pH and ionic strength was observed. The Mn contents of SPM mainly follow conservative mixing, but there are also indication…

Dasymetric distribution of votes in a dense city

2017

[EN] A large proportion of electoral analyses using geography are performed on a small area basis, such as polling units. Unfortunately, polling units are frequently redrawn, provoking breaks in their data series. Previous electoral results play a key role in many analyses. They are used by political party workers and journalists to present quick assessments of outcomes, by political scientists and electoral geographers to perform detailed scrutinizes and by pollsters and forecasters to anticipate electoral results. In this paper, we study to what extent more complex geographical approaches (based on a proper location of electors on the territory using dasymetric techniques) are of value in…

Limits to the fixed center approximation to Faddeev equations: The case of theϕ(2170)

2011

The fixed center approximation to the Faddeev equations has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper, we study the case of the $\ensuremath{\phi}(2170)$, which has been described by means of Faddeev equations as a resonant state of $\ensuremath{\phi}$ and $K\overline{K}$, and show the problems derived from the use of the fixed center approximation in its study. At the same time, we also expose the limitations of an alternative approach recently proposed.

Evidence of deep magma degassing and ascent by geochemistry of peripheral gas emissions at Mount Etna (Italy): Assessment of the magmatic reservoir p…

2003

[1] Five gas discharges in the area of Mount Etna volcano (Italy) and in the near Hyblean plateau have been monitored since 1996. All the emissions displayed low contributions from crustal fluids, whereas magmatic gases were the main component. Selective dissolution of these gases into hydrothermal aquifers has been recognized and modeled, allowing us to calculate the original composition of the magma-released gases. The inferred composition of the magmatic gases exhibits synchronous variations of He/Ne and He/CO2 ratios, which are coherent with the magma degassing process. On the basis of numerical simulations of volatile degassing from Etnean basalts we have computed the initial and final…

Syn- and post-eruptive mechanism of the Alaskan Ukinrek Maars in 1977

2008

The two alkali olivine basaltic Ukinrek Maars (East Maar and West Maar) and one scoria cone within East Maar erupted within eleven days (March 30–April 9, 1977) on the Alaskan Peninsula, 13 km north of Mt. Peulik, an andesite volcano of the Aleutian Range. The East Maar, with a diameter of 300 m, is located within a small graben system striking N 1100 E, oblique to the Aleutian trench in a distance of 350 km. On these tensional faults two eruption centres occur: The East Maar and a scoria cone on the southeastern margin of its crater bottom. The scoria cone was active more or less during the whole eruption activity of East Maar. The West Maar, with a diameter of 140 m, is located just west …