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The 2015 refugee crisis is at the center of public and political discourse across Europe, especially among nations that have accepted refugees. Utilizing ethnographic fieldwork and 48 in-depth interviews conducted in 2011 and 2016 with Iranians in Hamburg, Germany, this paper considers how the refugee crisis impacts the racial boundaries between Germans and immigrant communities. It details how the crisis has made ethnic nationalism, Islamophobia, anti-foreigner prejudice and racism more pronounced and salient throughout Germany. The interviews demonstrate that this climate affects Iranians in several ways: they cite feeling more threat and stigma, as well as experiences of marginality, perpetual foreignness, and discrimination. This research contributes to sociological scholarship on migration and race by examining how critical international events influence and shape processes of racialization, identity and belonging, and social boundaries and hierarchies.  相似文献   

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J L Bos 《The EMBO journal》1998,17(23):6776-6782
Ras, Rap1 and Ral are related small GTPases. While the function of Ras in signal transduction is well established, it has been recognized only recently that Rap1 and Ral also are activated rapidly in response to a large variety of extracellular signals. Between the three GTPase an intriguing interconnectivity exists, in that guanine nucleotide exchange factors for Ral associate with the GTP-bound form of both Ras and Rap1. Furthermore, Rap1 is considered to function as an antagonist of Ras signalling by trapping Ras effectors in an inactive complex. Here, I summarize the recent developments in understanding the functional relationship between these three GTPase and argue that Rap1 functions in a signalling pathway distinct from Ras, while using similar or identical effectors.  相似文献   

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We investigated the influence of drone size and potential reproductive quality on caste interactions by adding large drones reared in drone cells (DC drones; considered to be of higher quality) and small drones reared in worker cells (WC drones; of lower quality) to two observation colonies and monitoring worker–drone interactions and acceptance by workers. When initially introduced into the colonies more DC drones received trophallaxis, whereas more WC drones received aggression and eviction attempts from workers. Nevertheless, WC and DC drones were equally likely to be accepted by workers. For both drone types accepted individuals had slightly, but significantly greater weights than rejected males. Thus, workers discriminated between drones of different sizes and potential quality upon initial encounter, although these discriminations were not strongly associated with acceptance decisions. After drones were accepted, workers either showed no preference for interacting with WC or DC drones, or if a preference was shown it tended to favor WC drones. Compared to accepted DC drones, significantly more WC drones received grooming for longer periods of time and also spent more time engaged in all interactions with workers combined. DC and WC drones did not differ in the likelihood of receiving trophallaxis or the vibration signal, although for both interactions slightly more WC drones were recipients. Thus, workers may bias some interactions with accepted drones to favor smaller individuals with potential developmental deficiencies, in a manner that could contribute to the production of a greater total number of competitive males and increased colony reproductive output.  相似文献   

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A. F. G. Dixon 《Oecologia》1972,9(4):301-310
Summary The ability of the lime aphid to produce sexuals (males and females) as an alternative to parthenogenetic females is regulated by a timing mechanism (interval timer) which restrains the appearance of these morphs early in the year. In this species there are two interval timers: one controls the production of sexual females, and the other controls the production of males. Both intervals timers are sensitive to day-length and temperature but they respond in different ways.With the approach of autumn the waning effect of the interval timer inhibiting female production combined with the short day-lengths results in an increasing proportion of the aphids developing into sexual females. The restraining effect of the interval timer results in a gradual transition from parthenogenetic to gamic reproduction over a period of several generations and is still operational in the autumn. However, in this species even relatively long day conditions (17 h) can induce the development of oviparae. This low threshold of response to day-length combined with the short generation time results in the sexual morphs appearing very early in the year. This is of considerable adaptive significance in years when, as frequently happens, the aphids disappear locally before the onset of autumn.  相似文献   

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Summary A family in which an interstitial deletion of the X chromosome, del(X)(q13q21.3), is segregating was ascertained through a boy with cleft lip and palate, agenesis of the corpus callosum, and severe mental retardation. The possible causal relationship to his chromosome abnormality is discussed. Although the deletion occurred within the critical region, the mother showed no signs of gonadal dysgenesis. A phenotypically normal daughter was, as her mother, monosomic for this region of the X, and both showed random inactivation of the X chromosome.Supported in part by grants to E.N. from the Carl Petersen's Foundation (B 995) and the Danish Medical Research Council (512-4276)  相似文献   

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Summary Structures have been found in the locular space between the tapetal cells and megaspores in Selaginella argentea and S. kraussiana that enter the megaspore wall and extend to the plasma membrane of the megaspore cytoplasm. We have called these structures wicks. Unless special fixation procedures are used wicks are either very poorly preserved or not apparent. Wicks appear to be routes for the transport of materials from the tapetum to developing megaspores. The entry of the wicks into the megaspore wall and their passage throughout the wall implies that the megaspore wall of Selaginella is a three-dimensional mesh-work of inter-connecting spaces. Wicks have several macromolecular-sized subunits, and the results of our histochemical reactions indicated the presence of glycoprotein and/or mucopolysaccharide. X-ray microanalysis of the S. convoluta exospore showed that silicon is present in rod-shaped structures between units of the exospore in mature megaspores. Because of the size and form of the structures between the exospore units we consider that they are remnants of wicks stabilized by silicon.Present address:Cátedra de Palinologia, Museo de La Plata, Paseo del Bosque s/nro., 1900 La Plata, Argentina.  相似文献   

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Summary The fine structure of the holdfasts or rhizoids is described for the thraustochytriaceous organisms, Thraustochytrium motivum, Schizochytrium aggregatum, and an unidentified organism, denoted T-20, which resembles S. aggregatum and Labyrinthula spp. Labyrinthula algeriensis and L. minuta slime track ultrastructure is also described. The holdfasts, rhizoids, and tracks have the same basic fine structure and are collectively termed ectoplasmic nets. They are delimited by a unit membrane which is in continuity with the plasmalemma, contain no cytoplasmic organelles only membrane-limited cisternae, and contain a fibrogranular ground substance. The nets appear to arise from one or as many as 20 organelle complexes consist of an approximately disk-shaped electron-dense granular aggregate in which are embedded portions of cisternae of the endoplasmic reticulum or perinuclear clear continuum. The cisternae appear to contribute small (ca. 17 nm diameter) vesicles to the granular aggregate which coalesce to form internal membranes of the net elements. The sagenogenetosome underlies the plasmalemma where it evaginates to form the delimiting membrane of the main trunk element of the net. No continuous membrane separates the net contents from the cytoplasm, only the granular aggregate.In L. algeriensis, L. minuta, and T-20 the net is necessary for motility of nonflagellated, nonamoeboid cells. Presence of the nets is not associated with motility in S. aggregatum and T. motivum. The possible taxonomic significance of the observations is discussed.Contribution No. 456, Virginia Institute of Marine Science, Gloucester Point, Virginia 23062.Supported in part by the Oceanography Section, National Science Foundation, NSF Grant GA-31014.  相似文献   

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Concluding Remarks While the simple historical view has pictured the Lysenko controversy as an uninterrupted series of Lysenko's victories-beginning with the 1936 discussion, and culminating in the infamous August 1948 meeting of the Lenin All-Union Academy of Agricultural Sciences, when genetics was officially abolished in the Soviet Union-it was certainly more complex, as recognized by such serious historians as David Joravsky and Mark Adams. As we have seen, the roles the competitors assumed in 1945–47 were the reverse of those they assumed in the 1930s: the geneticists managed to gain the offensive, and Lysenko was forced to defend his position.This episode suggests that the Communist Party leadership probably did not have a special bias against genetics, nor a particular preference toward Lysenko at that time. The actual decisions of the Party apparatus on particular science policies were based upon the current priorities of general foreign and domestic policies, rather than upon an orthodox Party line in esoteric scientific questions. It is clear and has been recognized by some historians that the Soviet scientific community was not a passive, monolithic object of the manipulation, control, and repression exercised by the Communist Party leadership; various groups within the Soviet scientific community actively exploited every opportunity provided by the Party's policies to achieve their own objectives.The Lysenko controversy illustrates the profound impact of international events on Soviet science and suggests that its history cannot be understood as a result of exclusively domestic affairs, but should be explicated within a broader framework of interaction between Soviet domestic and international policies and between the Soviet and Western scientific communities. As we have seen, one of the major causes of the geneticists' success in the postwar struggle with Lysenkoists was the shift of Soviet foreign policies toward internationalism stimulated by the wartime alliance between the Big Three. This suggests that the so-called death of genetics in the Soviet Union in August 1948 was also the result of another dramatic shift in the international situation: the climax of the Cold War confrontation between former allies in the summer of 1948, which marked the final division of postwar Europe and the world into two opposing camps, East and West.  相似文献   

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Vegetation History and Archaeobotany - Grape (Vitis vinifera L. ssp. vinifera) has been identified as part of the Indus Civilization crop assemblage. As a non-native crop, with a wild ancestor that...  相似文献   

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This essay argues that stable, heritable, habituated semiotics on one scale of life allows for opportunism, origination, and the solving of novel problems on others. This is grounded in how interpretation is neither caused nor determined by its object, such that success at interpretation simply cannot be defined by any comparison between an interpretation and its object. Rather, an interpretation is a reciprocated incorporation of a living thing and its environment, and successful if it furthers the living, interpreting thing. By applying biosemiotic theory to seemingly disparate studies of parasitic infections (Jaroslav Flegr), autonomic nervous systems (Stephen Porges), and social change (Charles Tilly) as well as the classical pragmatic notion that biology, psychology and sociology are disparate approaches to the singular, radically continuous, and perennial question of who (or what) am I (Dewey, James, Mead). I argue that the distinction (e.g.,) between voluntary and autonomic behavior is but a ghost of older dualisms, the pseudo-contradictions of matter v. mind, body v. soul, but also self v. not self. Moreover, all such pseudo-contradictions (individual v. social, sensation v. response, parasite v. host, and etc.) are resolved as scale thick, self-similar examples of semiotic transaction wherein degeneration or habituation on one scale of life allows for generative or novel interaction on another.  相似文献   

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