170,199 research outputs found
In search of the genetic footprints of Sumerians: a survey of Y-chromosome and mtDNA variation in the Marsh Arabs of Iraq
No full textBackground
For millennia, the southern part of the Mesopotamia has been a wetland region generated by the Tigris and Euphrates rivers before flowing into the Gulf. This area has been occupied by human communities since ancient times and the present-day inhabitants, the Marsh Arabs, are considered the population with the strongest link to ancient Sumerians. Popular tradition, however, considers the Marsh Arabs as a foreign group, of unknown origin, which arrived in the marshlands when the rearing of water buffalo was introduced to the region.
Results
To shed some light on the paternal and maternal origin of this population, Y chromosome and mitochondrial DNA (mtDNA) variation was surveyed in 143 Marsh Arabs and in a large sample of Iraqi controls. Analyses of the haplogroups and sub-haplogroups observed in the Marsh Arabs revealed a prevalent autochthonous Middle Eastern component for both male and female gene pools, with weak South-West Asian and African contributions, more evident in mtDNA. A higher male than female homogeneity is characteristic of the Marsh Arab gene pool, likely due to a strong male genetic drift determined by socio-cultural factors (patrilocality, polygamy, unequal male and female migration rates).
Conclusions
Evidence of genetic stratification ascribable to the Sumerian development was provided by the Y-chromosome data where the J1-Page08 branch reveals a local expansion, almost contemporary with the Sumerian City State period that characterized Southern Mesopotamia. On the other hand, a more ancient background shared with Northern Mesopotamia is revealed by the less represented Y-chromosome lineage J1-M267*. Overall our results indicate that the introduction of water buffalo breeding and rice farming, most likely from the Indian sub-continent, only marginally affected the gene pool of autochthonous people of the region. Furthermore, a prevalent Middle Eastern ancestry of the modern population of the marshes of southern Iraq implies that if the Marsh Arabs are descendants of the ancient Sumerians, also the Sumerians were most likely autochthonous and not of Indian or South Asian ancestry
I patti parasociali hanno assunto efficacia reale? (nota a Trib. Genova, 8 luglio 2004 - Giudice Maganza - D. V. F. e B. P c. V. G. e Avv. M. E. e SPAFID S.p.a.)
No full textHLA Class I molecule expression is up-regulated during maturation of dendritic cells, protecting them from natural killer cell-mediated lysis
No full textFeasibility of methylmethacrylate polymerization for bone cement by suspension polymerization in a gel phase
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Normal epithelial cells modulating HLA class I surface molecules are susceptible to lysis mediated by CD3(+) and CD3(-) "nonspecific" killer cells.
No full textImproved Identification and Autotuning of PI Controllers for MIMO Processes by Relay Techniques
No full textA technique for on-line identification and tuning is proposed to be used in the framework of a MIMO autotuning procedure. The proposed technique does not suffer from the risks of instability and the lack in performance of common tuning techniques in MIMO autotuning. Identification is accomplished through an extension of the well known ATV autotune identification method and requires only few additional tests in order to obtain some more knowledge about the process. The resulting model, which describes with good precision the process in a region of frequencies around the critical point, is then used for tuning: the integral time is found as a function of the model time constants and delay, while the gain is computed in order to give a desired value of the closed-loop resonance peak. Examples of application show that advantages over other proposed techniques can be retained for processes having different dynamic characteristics
Modelling and sensitivity analysis of pyrolysis of biomass particles in a fluidised bed
No full textA detailed model is developed in order to describe the pyrolysis of biomasses in fluidised bed reactors. Preliminarly the physical and kinetic phenomena involved in the process are described. This work illustrates die level of detail the model for the particles must have in order to give reliable information and the way the model can be solved and coupled with the kinetics that take place outside the particles. A sensitivity analysis has supplied the parameters which influence relevantly the yields for different biomasses. (C) 1998 Elsevier Science Ltd. All rights reserved
The metaphorical construction of complex domains : the case of speech activity in English.
No full textIn this article I provide an account of the way in which the domain of spoken communication is metaphorically constructed in English, on the basis of the analysis of over 450 metaphorical references to speech activity in a corpus of contemporary written British English. I show how spoken communication is mainly structured via a set of source domains that conventionally apply to a wide variety of target domains, such as the source domains of MOTION, PHYSICAL TRANSFER, PHYSICAL CONSTRUCTION, and PHYSICAL SUPPORT. Each of these source domains structures a particular aspect of speech activity, such as the achievement of communicative goals, the expression of meanings and ideas, the performance of speech acts, the negotiation of mutual relationships, and so on. I suggest that the particular conceptual mappings that underlie the main patterns in my data are best seen in terms of Grady's (1997) notion of primary metaphors, that is, as simple, basic mappings that have a firm experiential basis and that apply to a wide range of different areas of experience (e.g., "HELP/ASSISTANCE IS SUPPORT"). However, I also show that the main primary metaphors involved in structuring the domain of speech activity can be combined into a single overall physical scenario in which interactants can move in different directions, place themselves in different positions in relation to each other, come into contact with each other in different ways, physically produce texts/utterances/speech acts, physically pass texts/utterances/speech acts to each other, and make meanings visible to each other in different ways. Finally, I argue that a corpus-based methodology has much to offer to metaphor research, particularly in the extrapolation of conceptual metaphors from linguistic data
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