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Search Results: 1 - 10 of 8292 matches for " Isabel Mendizabal "
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Genetic origin, admixture, and asymmetry in maternal and paternal human lineages in Cuba
Isabel Mendizabal, Karla Sandoval, Gemma Berniell-Lee, Francesc Calafell, Antonio Salas, Antonio Martínez-Fuentes, David Comas
BMC Evolutionary Biology , 2008, DOI: 10.1186/1471-2148-8-213
Abstract: The Native American contribution to present-day Cubans accounted for 33% of the maternal lineages, whereas Africa and Eurasia contributed 45% and 22% of the lineages, respectively. This Native American substrate in Cuba cannot be traced back to a single origin within the American continent, as previously suggested by ancient DNA analyses. Strikingly, no Native American lineages were found for the Y-chromosome, for which the Eurasian and African contributions were around 80% and 20%, respectively.While the ancestral Native American substrate is still appreciable in the maternal lineages, the extensive process of population admixture in Cuba has left no trace of the paternal Native American lineages, mirroring the strong sexual bias in the admixture processes taking place during colonial times.At the time of the arrival of Columbus to Cuba in 1492, two different Native American groups inhabited the island: the Ciboneys, spread across the whole island, and the Tainos, mainly occupying the Central and Eastern regions of Cuba [1]. Although not much is known of Ciboney culture including their language, it is known that their economy was based on hunter-gathering (mainly fishing and hunting) and lacked pottery, unlike the Tainos, who were sedentary people living in large settlements and whose culture was supported by technically advanced agriculture. The social organization of the Tainos was based on chiefdoms, in which the caciques were the social authority. The Tainos spoke Arawakan, a language belonging to both the Equatorial sub-family and the Equatorial-Tucanoan family [1].Who first colonized the Caribbean islands is still a matter of debate. Geographical, archaeological and linguistic evidence [2-4], as well as ancient DNA data [5,6] suggest that the Caribbean was most likely populated by successive waves of migration originating in the Lower Orinoco Valley in South America, taking advantage of the close geographical proximity of the islands in the Caribbean. Therefo
THEORETICAL STUDY OF THE S2-P INTERACTION BETWEEN TL(I) AND OLEFINIC SYSTEMS ON HYPOTHETICAL [TL(c2H4)2]+ And [TL(c2H2)n]+ (N = 2,3) COMPLEXES
DONOSO,DANIELA; MENDIZABAL,FERNANDO;
Journal of the Chilean Chemical Society , 2010, DOI: 10.4067/S0717-97072010000400020
Abstract: the attraction between [c2hj2 and [c2hj23 and tl(i) in the hypothetical [tl(c2h4)2]+ and [tl(c2h2)n]+ (n = 2,3) complexes was studied using ab initio methods. it was found that the changes around the equilibrium c-tl distance and in the interaction energies are sensitive to the electron correlation potential. we evaluated these effects using several levels of theory, including hf, mp2, mp4 and ccsd(t). the equilibrium c-tl distances in the complexes are in the range of 294 pm to 338 pm. the interaction energy differences obtained at the equilibrium distance range from 55 to 110 kj/mol at the different levels used. these results indicate that the complexes formed are in the category of van der waals systems. also, these results indicated that the interaction between olefinic systems and tl(i) are a real minimum on the potential energy surfaces.
EXPONENTIAL DECAY OF A CHARGE TRANSFER INDUCED BY COORDINATION IN ORGANOMETALLIC COMPLEXES
DIAZ,CARLOS; MENDIZABAL,FERNANDO;
Boletín de la Sociedad Chilena de Química , 2001, DOI: 10.4067/S0366-16442001000300009
Abstract: in the series of organometallic complexes n3p2(x)5p-spacer-mln x= cl and or, mln= organometallic fragment , the d31 p-nmr coordination chemical shift parameter correlates with the length of the spacer, decaying exponentially with the length of it. the bridging spacers behave like a "molecular wire" showing dependence of the charge transfer with the distance, similar to electron transfer in donor-acceptor systems. extended hückel molecular orbital calculations on the model series n3p2(x)2 p-spacer-mln x=cl- and oh- molecules shows that the changes of the mulliken charges on the phosphorus and metal atoms upon coordination exhibits also an exponential dependence with the length of the spacer
THEORETICAL STUDY OF THE S2-P INTERACTION BETWEEN TL(I) AND OLEFINIC SYSTEMS ON HYPOTHETICAL [TL(c2H4)2]+ And [TL(c2H2)n]+ (N = 2,3) COMPLEXES
DANIELA DONOSO,FERNANDO MENDIZABAL
Journal of the Chilean Chemical Society , 2010,
Abstract: The attraction between [C2HJ2 and [C2HJ23 and Tl(I) in the hypothetical [Tl(C2H4)2]+ and [Tl(C2H2)n]+ (n = 2,3) complexes was studied using ab initio methods. It was found that the changes around the equilibrium C-Tl distance and in the interaction energies are sensitive to the electron correlation potential. We evaluated these effects using several levels of theory, including HF, MP2, MP4 and CCSD(T). The equilibrium C-Tl distances in the complexes are in the range of 294 pm to 338 pm. The interaction energy differences obtained at the equilibrium distance range from 55 to 110 kJ/mol at the different levels used. These results indicate that the complexes formed are in the category of van der Waals systems. Also, these results indicated that the interaction between olefinic systems and Tl(I) are a real minimum on the potential energy surfaces.
EXPONENTIAL DECAY OF A CHARGE TRANSFER INDUCED BY COORDINATION IN ORGANOMETALLIC COMPLEXES
CARLOS DIAZ,FERNANDO MENDIZABAL
Boletín de la Sociedad Chilena de Química , 2001,
Abstract: In the series of organometallic complexes N3P2(X)5P-SPACER-MLn X= Cl and OR, MLn= organometallic fragment , the delta31 P-NMR coordination chemical shift parameter correlates with the length of the spacer, decaying exponentially with the length of it. The bridging spacers behave like a "molecular wire" showing dependence of the charge transfer with the distance, similar to electron transfer in donor-acceptor systems. Extended Hückel molecular orbital calculations on the model series N3P2(X)2 P-SPACER-MLn X=Cl- and OH- molecules shows that the changes of the Mulliken charges on the phosphorus and metal atoms upon coordination exhibits also an exponential dependence with the length of the spacer En la serie de complejos N3P2(X)5P-ESPACIADOR-MLn X= Cl y OR, MLn= fragmento organometálico, el parámetro de corrimiento químico de coordinación delta31P-NMR, correlaciona con la longitud del espaciador, decayendo exponencialmente con la longitud de éste. El puente espaciador se comporta similarmente a un "hilo molecular" mostrando una dependencia de la transferencia de carga con la distancia, similar a la transferencia de carga en sistemas dador-aceptor. Cálculos de orbitales moleculares del tipo Hückel extendido en la serie de moléculas N3P2(X)2 P-ESPACIADOR-MLn X=Cl- y OH- muestran que al ocurrir la coordinación, los cambios de las cargas de Mulliken sobre los átomos de fósforo y del metal exhiben también una dependencia con la longitud del espaciador
Relativistic scattering with a singular potential in the Dirac equation
M Loewe,S Mendizabal
Physics , 2004,
Abstract: An elementary treatment of the Dirac equation in the presence of a three dimensional spherically symmetric delta potential is presented. We show how to calculate the cross section using the relativistic wave expansion method for a one delta potential and two concentric delta potentials. We compare our results with the cross section calculated in the Born approximation.
Estudio Antropológico y Patológico de Cementerios Altomedievales en el País Vasco.Los casos del despoblado de Aistra y el Castillo de Trevi o.
Mendizabal Gorostizu-Orkaiztegi, Amaia
Munibe Antropologia-Arkeologia , 2011,
Abstract: En el presente artículo se exponen los resultados obtenidos del análisis paleopatológico y antropológico de los restos óseos recuperados en dos aldeas alto-medievales alavesas. A partir de estos, se ha podido realizar un estudio comparativo de los dos grupos sociales analizados. Así mismo, se ha podido realizar un estudio comparativo de los dos espacios de enterramiento que han sido estudiados.
Reconstructing the Indian Origin and Dispersal of the European Roma: A Maternal Genetic Perspective
Isabel Mendizabal,Cristina Valente,Alfredo Gusm?o,Cíntia Alves,Verónica Gomes,Ana Goios,Walther Parson,Francesc Calafell,Luis Alvarez,António Amorim,Leonor Gusm?o,David Comas,Maria Jo?o Prata
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015988
Abstract: Previous genetic, anthropological and linguistic studies have shown that Roma (Gypsies) constitute a founder population dispersed throughout Europe whose origins might be traced to the Indian subcontinent. Linguistic and anthropological evidence point to Indo-Aryan ethnic groups from North-western India as the ancestral parental population of Roma. Recently, a strong genetic hint supporting this theory came from a study of a private mutation causing primary congenital glaucoma. In the present study, complete mitochondrial control sequences of Iberian Roma and previously published maternal lineages of other European Roma were analyzed in order to establish the genetic affinities among Roma groups, determine the degree of admixture with neighbouring populations, infer the migration routes followed since the first arrival to Europe, and survey the origin of Roma within the Indian subcontinent. Our results show that the maternal lineage composition in the Roma groups follows a pattern of different migration routes, with several founder effects, and low effective population sizes along their dispersal. Our data allowed the confirmation of a North/West migration route shared by Polish, Lithuanian and Iberian Roma. Additionally, eleven Roma founder lineages were identified and degrees of admixture with host populations were estimated. Finally, the comparison with an extensive database of Indian sequences allowed us to identify the Punjab state, in North-western India, as the putative ancestral homeland of the European Roma, in agreement with previous linguistic and anthropological studies.
THEORETICAL STUDY OF COPPER-CARBONYLS INTERACTION IN CU(CO)N (N=1-2) COMPLEXES
Cerón,María Luisa; Mendizabal,Fernando;
Journal of the Chilean Chemical Society , 2003, DOI: 10.4067/S0717-97072003000400013
Abstract: we studied the dependence on the attraction between copper(0) and carbonyls in cu(co)n (n = 1-2) complexes using ab initio methodology. oscillation in the equilibrium cu-c distance, as well as on the interaction energy are sensitive to the electron correlation potential. these effects were evaluated using several levels of theory, ranging from mp2 to ccsd(t). the long-distance behaviour of the cuco interaction is related to simple induction and dispersion expressions involving the individual properties of both copper and carbonyl. the dispersion interaction is the principal contribution in the stability at long distance and an important term at short distance
NEW ENTRY TO PIANO -STOOL ELECTRON RICH (PENTAMETHYL CYCLOPENTADIENYL) IRON COMPLEXES
DIAZ,C.; CABEZAS,N.; MENDIZABAL,F.;
Boletín de la Sociedad Chilena de Química , 2002, DOI: 10.4067/S0366-16442002000300003
Abstract: a new route to the electron rich pentamethylcyclopetadienyl iron complexes (n5-c5me5)=cp*) starting from the commercially available dimer [cp*fe(co)2]2 ,is presented. reaction of the dimer with i2 in ch2cl2, affords the mononuclear carbonyl complex cp*fe(co)2i which in turn reacts with bis(diphenylphosphinoethane) in toluene under uv irradiation to give cp*fe(dppe)i. treatment of cp*fe(dppe)i with the neutral ligands l (l = ch3cn, pph3, set2) in the presence of tlpf6 affords the cationic derivatives [cp*fe(dppe)l]pf6 ,while that the reaction with s2(ch2c6h5 )2 in ch3oh yields the thiolate complex [cp*fe(dppe)s-ch2c6h5 ] pf6 .the unusual magnetic properties of these complexes are discussed. extended hückel om calculation confirmed the most electron rich character of the cp*fe(dppe)+ derivatives than their unsustituted cpfe(dppe)+ .electrochemical as well as m?sbauer data are in agree with this
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