260 research outputs found
The formation of loess ground by the process of loessification: a history of the concept
Loessification is a process by which a body of non-loess ground is transformed into a body of loess ground. The history of loessification is one of controversy and confrontation, largely because of mutual misunderstandings between geologists and pedologists. Lev S. Berg is the âonly begetterâ of the theory, first proposed in 1916, and propagated throughout his life. R.J. Russell proposed the same approach to the loess in the Lower Mississippi valley in his famous 1944 paper, which contributed enormously to the study of loess in North America. As understanding of the various processes involved in the formation of loess deposits has developed, a compromise position on loess formation has become possible. The major intrinsic features of loess deposits are the open structure and the collapsibility. It appears that the open structure is caused by aeolian depositional processes and the collapsibility is caused by loessification processes. The compromise was initiated by Marton PĂ©csi in 1990, He endeavoured to retain a loessification aspect in the study of loess deposits, as the subject appeared to be overwhelmed by the aeolian idea system promoted by geologists; it has been mostly a Central European endeavour. The history of the concept of loessification largely involves (1) its development in Russia, (2) its dissemination and discussion â and attempts at refutation and modification â in the wider world
TĂ©a Obrehtâs Transnational Disremembering within the Mythical Realism of The Tigerâs Wife
This paper discusses TĂ©a Obreht's 2010 novel The Tiger's Wife within the context of transmigrations and post-national conceptions of both the real and mythical translocality. Through analysis of Obrehtâs discourse of disremembering, which is in Aleksandar Hemonâs definition a recognition of oneâs own experience under the new narrative, the paper will explore the transnational dimensions of the Slavic-American identity of The Tigerâs Wife. The aim of this paper is to focus on the new understanding of transnational relationality as well as on a reconception of reality that disremembers Obrehtâs or, on a larger scale, human experience within the mythical realism of The Tigerâs Wife.Keywords: transnationalism, the Slavic-American identity, disremembering, Aleksandar Hemon, TĂ©a Obreht, The Tigerâs Wife, mythical realismTo disremember, according to Aleksandar Hemon, a celebrated Bosnian-American writer with an immigrant experience, is to recognize oneâs own experience under the new narrative. He points out that it especially refers to the âpeople who have come through a form of actual, physical slaughter, and to the extent the construction of narrative is memory, then the narrative, for them, has to involve a quantity of amnesia. More amnesia that is involved in most narrativeâ (Interview by Richard Wirick). Disremembering blends non-fiction and fiction, genocide documentation and utopian imagery, and implies an alternative interpretation of reality. Hemonâs 2008 novel The Lazarus Project is a transnational project of disremembering. In The Lazarus Project, Hemon intertwines a double narrative of the multilayered parallel universes of the past and the present by following the narrator Vladimir Brik, a post-war Bosnian who lives in the United States, as he questions his life. Brik traces the story of Lazarus Averbuch, a young Jewish immigrant who is a survivor of the Kishinev pogrom in what is now Moldova, and an alleged anarchist. At the same time, Brik questions both the inner and outer aspects of his reality. In the first-person narrative, he explains that he needs to re-imagine what he could not retrieve, and to see what he could not imagine. For this reason, he disremembers his own experience within the story of Lazarus that also implies resurrection and a new birth story. This paper will analyze TĂ©a Obrehtâs evocative 2010 novel The Tiger's Wife from the point of view of a Hemonesque narrative concept of disremembering and, within the discourse, an Obrehtesque interaction of myth and truth
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Tracing the influence of Mediterranean climate on Southeast Europe during the past 350,000 years
Although global patterns of past climate change are relatively well established at the scale of orbital forcing, local responses in various regions are still not understood. Loess-paleosol sequences (LPS) are valuable archives of past environmental changes in Southeast Europe. However, most LPSs seem to be limited in their sensitivity to paleoclimate due to an overall imprint of enhanced dryness in the region during loess sedimentation. Here we present the results from the StalaÄ section in the Central Balkans, one of the first high-resolution multiproxy LPS records spanning the past ~350,000 years in Southeast Europ
An integrated approach to delimiting species borders in the genus Chrysotoxum Meigen, 1803 (Diptera: Syrphidae), with description of two new species
Integrative taxonomy tests the validity of taxa using methods additional to traditional morphology. The existence of two different morphotypes in specimens identified as Chrysotoxum vernale Loew (Diptera: Syrphidae) prompted their taxonomic study using an integrative approach that included morphology, wing and male-surstylus geometric morphometrics, genetic and ecological analyses. As a result, a new species is recognised, Chrysotoxum montanum NedeljkoviÄ & VujiÄ sp. nov., and C. vernale is re-defined. A lectotype and paralectotypes are designated for C. vernale to stabilize this concept. An additional species, Chrysotoxum orthostylum VujiÄ sp. nov., with distinctive male genitalia is also described. The three species share an antenna with the basoflagellomere shorter than the scape plus pedicel and terga with yellow fasciae not reaching the lateral margins. This study confirms the value of integrative approach for resolving species boundaries.Financial support was provided by the Serbian Ministry of Education, Science and Technological Development (projects OI173002 and III43002), the Provincial Secretariat for Science and Technological Development (project âGenetic resources of agro-ecosystems in Vojvodina and sustainable agricultureâ), the Transnational Access to Research Infrastructures activity in the FP7 of the EC (ExpeER project, TA visit âSTEPSâ) and the FP7 EU project, Innosense
Kompozicija subjedinica glutenina velike molekulske mase kod NS sorti pĆĄenice priznatih u periodu 1987-2008.
Gluten content, and more importantly its composition expressed through glutenin subunits, has great influence on the rheological and bread-making properties of wheat flour. Total of 168 winter wheat cultivars developed at the Institute of Field and Vegetable Crops, Novi Sad, Serbia in the period 1987-2008 were analysed for high molecular weight glutenin subunits (HMWGS) composition using SDS-PAGE. Presence of twelve different alleles and nineteen different GS combinations was determined. The highest frequency was found for GS N at the locus Glu-A1 (46%), 7+9 (77%) at the locus Glu-B1 and 5+10 (72.7%) at the locus Glu-D1. The most frequent combination was 2*, 7+9, 5+10. Presence of several rare GS with positive effect (13+16 and 15+16) was determined, as well as high uniformity of the genetic material, considering small number of cultivars (4.2%) with different electrophoretic paths. Two modes of glutenin score (Glu-1 score) determination were applied, based on which differences in bread-making quality among individual cultivars can be determined more precisely.SadrĆŸaj glutena, ali pre svega njegova kompozicija izraĆŸena kroz gluteninske subjedinice, znaÄajno utiÄe na reoloĆĄke i pekarske pokazatelje pĆĄeniÄnog braĆĄna. Kod ukupno 168 sorti ozime pĆĄenice stvorenih u Institutu za ratartsvo i povrtartsvo u Novom Sadu, u periodu od 1987. do 2008. godine, analizirana je kompozicija subjedinica glutenina velike molekulske mase (HMW-GS) koristeÄi SDS-PAGE. UtvrÄeno je prisustvo dvanaest razliÄitih alela i devetnaest razliÄitih kombinacija GS. NajveÄa uÄestalost uoÄena je kod GS N u lokusu Glu-A1 (46%), 7+9 (77%) u lokusu Glu-B1 i 5+10 (72,7%) u lokusu Glu-D1. Najzastupljenija kombinacija je bila 2*, 7+9, 5+10. UtvrÄeno je prisustvo nekoliko retkih GS sa pozitivnim dejstvom (13+16 i 15+16) i visoka ujednaÄenost genetskog materijala, s obzirom na mali broj sorti (4.2%) sa razliÄitim elektroforetskim putanjama. Primenjena su dva naÄina utvrÄivanja gluteninskog (Glu-1) skora, na osnovu Äega se mogu preciznije utvrditi razlike u krajnjem kvalitetu izmeÄu pojedinih sorti
Case-control study of apoE gene polymorphism in young CHD patients and controls in the Serbian population
Apolipoprotein E displays polymorphism with three common alleles, e2, e3, and e4. The aim of this research was to determine apoE gene polymorphism in a group of healthy patients and a group of patients with CHD, and to reveal the relation between anthropometric and biochemical parameters and the apoE genotype. In CHD group significantly higher values of blood pressure, waist circumference, BMI and fat %, triglycerides, insulin (HOMA IR) and CRP were found. A statistically significant higher presence of the e3e4 genotype and e4 allele was detected in the CHD group. Statistically significant differences between waist circumference, BMI, insulin and HOMA IR were found between subjects with e3e3 and e3e4 genotypes
Cyanobacteria and loess-an underestimated interaction
Background: Biocrusts are important functional units in dryland ecosystems. Regarded as ecosystem engineers, cyanobacteria in biocrusts contribute several major physico-chemical and biological processes. However, the role of cyanobacteria in the process of loess formation has been underestimated. Recently, their contribution to sediment development was presented in the BLOCDUST model of loess formation. Scope: This perspective paper features the environmental impact of cyanobacteria and biocrusts with a focus on processes involved in the formation of loess sediments. We propose that the formation of loess can be mediated by cyanobacteria, including initial trapping, and the accumulation and preservation of loess-forming particles. Moreover, the initial structure may be further altered by weak mineral weathering, dissolution and mineral re-precipitation due to cyanobacterial metabolic processes. Possible negative aspects of environmental impact related to the potential toxicity of cyanobacterial biocrusts are also discussed. We highlight specific biotic-abiotic interactions between biocrusts and loess (e.g. exudation of organic polymers, carbonate dissolution and re-precipitation, and dust-dependent metabolic activities of cyanobacteria) which are essential for the formation of stabilized loess and propose the term âsynergosisâ to comprise these interactions. Conclusion: The role of cyanobacteria in loess formation has only recently been recognized and the possible biogenic nature of loessification is underestimated as compared to their eolian nature. Mineral weathering and mineral precipitation processes as well as mineral dust flux between litho- and atmosphere mediated by cyanobacteria and biocrusts require more attention due to their significant contribution to ecosystem properties
Close relatives of Mediterranean endemorelict hoverflies (Diptera, Syrphidae) in South Africa : Morphological and molecular evidence in the Merodon melanocerus subgroup
An ongoing study of the genus Merodon Meigen, 1803 in the Republic of South Africa (RSA) has revealed the existence of new species related to M. melanocerus Bezzi, 1915. The M. melanocerus subgroup belongs to the Afrotropical lineage of the M. desuturinus group. Revision of all available material from museums and detailed analyses of newly -collected specimens from our own expeditions to RSA resulted in delimitation of five species: M. capensis Hurkmans sp. n., M. commutabilis Radenkovic et Vujic sp. n., M. drakonis Vujic et Radenkovic sp. n., M. flavocerus Hurkmans sp. n. and M. melanocerus. In addition to classical morphological characters, sequences of the mitochondrial COI gene are provided for four related taxa. Results of molecular phylogenetic analyses supports monophyly of the M. desuturinus group and confirmed delimitation between species. Links between Palaearctic and Afrotropical faunas of this group, as well as possible evolutionary paths, are discussed. Based on phylogenetic analyses, four lineages (putative subgenera) have been recognized within the genus Merodon; besides the three previously established ones, albifrons+desuturinus, aureus (sensu lato) and avidus-nigritarsis, one new lineage named natans is distinguished.Peer reviewe
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