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This paper analyzes how on-the-job search (OJS) by an agent impacts the moral hazard problem in a repeated principal-agent relationship. OJS is found to constitute a source of agency costs because efficient search incentives require that the agent receives all gains from trade. Further, the optimal incentive contract with OJS matches the design of empirically observed compensation contracts more accurately than models that ignore OJS. In particular, the optimal contract entails excessive performance pay plus efficiency wages. Efficiency wages reduce the opportunity costs of work effort and hence serve as a complement to bonuses. Thus, the model offers a novel explanation for the use of efficiency wages. When allowing for renegotiation, the model generates wage and turnover dynamics that are consistent with empirical evidence. I argue that the model contributes to explaining the concomitant rise in the use of performance pay and in competition for high-skill workers during the last three decades.
The ground beetle genus Cymindis is the most species rich amongst genera in the carabid subtribe Cymindidina (tribe Lebiini). Four subgenera are often recognized, i.e. Cymindis (sensu stricto) Latreille, Afrotarus Jeannel, Taridius Chaudoir and Pinacodera Schaum. Cymindis (sensu stricto) has a predominately Holarctic distribution (Hunting 2013) and includes Cymindis alutacea Wollaston, C. dohrnii Wollaston and C. anchomenoides Wollaston (the last one sometimes placed in Tarulus Bedel, either ranked as a genus or a subgenus), all three endemic to the Cape Verde Islands (Geisthardt 1988, 1996).
A checklist and classification of the species of Elateridae reported from mainland Ecuador are given. Anchastus boulardi Chassain, Cardiorhinus apicalis Golbach, Physorhinus marginatus Candèze, and P. sexnotatus Steinheil are reported from Ecuador for the first time. The recorded elaterid fauna of Ecuador is now represented by 140 species, 38 genera, and 9 subfamilies, which are low taxon richness numbers when compared to those of neighboring countries.
Ribosome biogenesis in yeast requires 75 small nucleolar RNAs (snoRNAs) and a myriad of cofactors for processing, modification, and folding of the ribosomal RNAs (rRNAs). For the 19 RNA helicases implicated in ribosome synthesis, their sites of action and molecular functions have largely remained unknown. Here, we have used UV cross-linking and analysis of cDNA (CRAC) to reveal the pre-rRNA binding sites of the RNA helicase Rok1, which is involved in early small subunit biogenesis. Several contact sites were identified in the 18S rRNA sequence, which interestingly all cluster in the “foot” region of the small ribosomal subunit. These include a major binding site in the eukaryotic expansion segment ES6, where Rok1 is required for release of the snR30 snoRNA. Rok1 directly contacts snR30 and other snoRNAs required for pre-rRNA processing. Using cross-linking, ligation and sequencing of hybrids (CLASH) we identified several novel pre-rRNA base-pairing sites for the snoRNAs snR30, snR10, U3, and U14, which cluster in the expansion segments of the 18S rRNA. Our data suggest that these snoRNAs bridge interactions between the expansion segments, thereby forming an extensive interaction network that likely promotes pre-rRNA maturation and folding in early pre-ribosomal complexes and establishes long-range rRNA interactions during ribosome synthesis.
Background: According to current taxonomy only three out of 27 Sinohimalayan leaf warbler species (Phylloscopidae) are considered genetically uniform across their entire breeding range along the Southeastern margin of the Qinghai-Tibetan Plateau, the Buff-barred Warbler (Phylloscopus pulcher) being one of them. Because marked differentiation among Himalayan and Chinese populations has been recently demonstrated for a number of Phylloscopus species (or sister species) we investigated the intraspecific variation of a mitochondrial gene, songs and morphology of P. pulcher in a phylogeographic approach.
Methods: We sequenced a fragment of the mitochondrial cytochrome b, reconstructed haplotype networks and analyzed DNA polymorphism among Himalayan and Chinese populations. We measured time and frequency parameters of two distinct song types and analyzed among population-differentiation in a principal component analysis and a discriminant analysis. We also compared measurements of body size dimensions taken from museum specimens.
Results: The mitochondrial haplotype network (cytb) was divided into two distinct clusters corresponding to geographic origin of samples. Pairwise genetic distances among Himalayan and Chinese mtDNA lineages account for 1.3% which coincides with Pleistocene lineage separation at roughly 650,000 years ago. Genetic diversity is slightly higher in the Chinese part of the species’ range with respect to haplotype and nucleotide diversity while the less diversified Himalayan population lineage shows signs of recent range expansion. The vocal repertoire of P. pulcher comprises two distinct verse types that are combined with short interspersed click notes to long continuous song displays. Trill verse types showed significant differences among regions in almost all measured frequency and time parameters: Chinese males displayed more rapid and more broad-banded trills at a lower pitch. In contrast, warbling verse types showed a distinctively different structure among regions: Himalayan songs consisted of repeated syllables while Chinese songs comprised repetitions of single, long and strongly modulated elements. Subtle morphological differences among specimens from the two study regions could only be confirmed for plumage coloration but not for metric characters.
Conclusions: Based on the genetic and bioacoustic distinctiveness of Chinese Buff-barred Warbler populations, we recommend that the name Phylloscopus pulcher vegetus Bangs, 1913 should be re-validated for this taxon.
A child of a Jewish family fleeing Nazi-Germany and settling in apartheid South Africa in the 1930s, Ruth Weiss? journalistic career starts in Johannesburg of the 1950s. In 1968 banned from her home country, and then also from Rhodesia for her critical investigative journalism, she starts reporting from Lusaka, London and Cologne on virtually all issues which affect the newly independent African countries. Peasants and national leaders in southern Africa ? Ruth Weiss met them all, travelling through Africa at a time when it was neither usual for a woman to do so, nor to report for economic media as she did. Her writing gained her the friendship of diverse and interesting people. In this book she offers us glimpses into some of her many long-nurtured friendships, with Kenneth Kaunda or Nadine Gordimer and many others. Her life-long quest for tolerance and understanding of different cultures shines through the many personalized stories which her astute eye and pen reveals in this book. As she put it, one never sheds the cultural vest donned at birth, but this should never stop one learning about and accepting other cultures.
A versatile synthetic procedure is described to prepare the benzimidazole-fused 1,2,4-thiadiazoles 2a–c via a methanesulfonyl chloride initiated multistep cyclization involving the intramolecular reaction of an in-situ generated carbodiimide with a thiourea unit. The structure of the intricate heterocycle 2a was confirmed by single-crystal X-ray analysis and its mechanism of formation supported by DFT computations.
Riley (1979)'s reactive equilibrium concept addresses problems of equilibrium existence in competitive markets with adverse selection. The game-theoretic interpretation of the reactive equilibrium concept in Engers and Fernandez (1987) yields the Rothschild-Stiglitz (1976)/Riley (1979) allocation as an equilibrium allocation, however multiplicity of equilibrium emerges. In this note we imbed the reactive equilibrium's logic in a dynamic market context with active consumers. We show that the Riley/Rothschild-Stiglitz contracts constitute the unique equilibrium allocation in any pure strategy subgame perfect Nash equilibrium.
In spring and summer 2008, the Odonata fauna of the Khabr National Park (Iran) was studied for the first time. Here, we present records of the representatives of family Libellulidae only. A total of twelve libellulid Odonata were found. Most of them are common species in Iran and other parts of Kerman province. Scarce Iranian species are Trithemis arteriosa and Zygonyx torridus.
In the present paper, we concentrate on (selected) Bantu and Nilotic bare-passive strategies and lay out the basis for a typology of transitive passive constructions in these languages. We argue that bare-passives constitute an optimal strategy to change prominence relations between arguments, in languages that strongly hold to the default mapping between the highest thematic role available and the grammatical subject (i.e. Spec,TP). The Nilotic and Bantu languages discussed here differ in their way of satisfying this default mapping. In particular, impersonal bare-passives satisfy it by resorting to an agentive place-holder (an indefinite subject marker) and realizing the logical agent as a lower thematic/semantic role (e.g. instrument or locative). Left-dislocation and so called 'subjectobject' reversal bare-passives realize the default matching between agent and subject in a more straightforward way, but locate the patient in a higher argument position within the inflectional domain (Spec,TopP). As argued in Hamlaoui and Makasso (2013) and Hamlaoui (2013), and in line with Noonan (1977), the present languages display a clauseinternal split between subjecthood (being the grammatical subject in Spec,TP) and topicality (being the subject of the predication, in an inflectional-domain internal Spec,TopP).
Background: A discontinuous dose response relationship is a major characteristic of the anti-inflammatory effects of low-dose X-irradiation therapy. Although recent data indicate an involvement of a variety of molecular mechanisms in these characteristics, the impact of reactive oxygen species (ROS) production to give rise or contribute to these phenomena in endothelial cells (EC) remains elusive.
Material and methods: HUVEC derived immortalized EA.hy926 cells were stimulated by tumor necrosis factor-α (TNF-α, 20 ng/ml) 4 h before irradiation with doses ranging from 0.3 to 1 Gy. To analyse DNA repair capacity, phospho-histone H2AX foci were assayed at 1 h, 4 h and 24 h after irradiation. ROS production and superoxide dismutase (SOD) activity were analysed by fluorometric 2',7'-dichlorodihydrofluorescein-diacetate (H2DCFDA) and colorimetric assays. A functional impact of ROS on γH2AX production was analysed by treatment with the scavenger N-acetyl-L-cysteine (NAC).
Results: Irrespective of stimulation by TNF-α, EA.hy926 cells revealed a linear dose response characteristic of γH2AX foci detection at 1 h and 4 h after irradiation. By contrast, we observed a discontinuity in residual γH2AX foci detection at 24 h after irradiation with locally elevated values following a 0.5 Gy exposure that was abolished by inhibition of ROS by NAC. Moreover, SOD protein expression was significantly decreased at doses of 0.5 Gy and 0.7 Gy concomitant with a reduced SOD activity.
Conclusion: These data implicate a non-linear regulation of ROS production and SOD activity in EA.hy926 EC following irradiation with doses < 1 Gy that may contribute to a discontinuous dose-response relationship of residual γH2AX foci detection.
Xylotrechus rameyi, new species, (Coleoptera: Cerambycidae) is described from southern Utah. Comments on its biology including habitat, host plants and larval history are provided along with photographs of the holotype, allotype, the related species X. insignis LeConte, and the larval galleries and pupal chamber.
A new species of soft scale from Mexico, Toumeyella martinezi Kondo and Gonzalez sp. nov. (Hemiptera: Coccoidea: Coccidae) collected on Myrtillocactus geometrizans (Mart. ex Pfeiff.) Console (Cactaceae) is described and illustrated. An updated taxonomic key to the soft scale insects of the genus Toumeyella Cockerell known from Mexico is provided. A list of all currently known species of Toumeyella worldwide is given.
A new species of the genus Onychopygia Beier, 1962 Orthoptera: Tettigoniidae: Pseudophyllinae) from the northern slopes of Los Cuchumatanes Mountains, Huehuetenango, Guatemala is described and illustrated. The morphological differences and peculiarities between O. panamensis Beier, 1962 and O. brachyptera n. sp. are discussed. The finding of this new taxon extends considerably into entral America our previous knowledge on the distribution of the Eucocconotini tribe. Finally we provide a revised taxonomic key to the Eucocconotini tribe.
A new species of Nephus Mulsant (Coleoptera: Coccinellidae) from southern Florida is described: Nephus (Nephus) alyssae. This represents the fi rst member of the subgenus Nephus reported in the southeastern United States. Florida species previously placed in the genus Nephus, now placed in Scymnobius Casey, are compared with the new species.