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Unexplored
Terms modified by Unexplored Selected AbstractsVIOLENCE AMONG ADOLESCENTS LIVING IN PUBLIC HOUSING: A TWO-SITE ANALYSIS,CRIMINOLOGY AND PUBLIC POLICY, Issue 1 2003TIMOTHY O. IRELAND Research Summary: Current knowledge about violence among public housing residents is extremely limited. Much of what we know about violence in and around public housing is derived from analysis of Uniform Crime Report (UCR) data or victimization surveys of public housing residents. The results of these studies suggest that fear of crime among public housing residents is high and that violent offense rates may be higher in areas that contain public housing compared with similar areas without public housing. Yet, "[r]ecorded crime rates (and victimization rates) are an index not of the rate of participation in crime by residents of an area, but of the rate of crime (or victimization) that occurs in an area whether committed by residents or non-residents" (Weatherburn et al., 1999:259). Therefore, neither UCR nor victimization data measurement strategies address whether crime in and around public housing emanates from those who reside in public housing. Additionally, much of this research focuses on atypical public housing,large developments with high-rise buildings located in major metropolitan areas. To complement the existing literature, we compare rates of self-reported crime and violence among adolescents who reside in public housing in Rochester, N.Y., and Pittsburgh, Pa., with adolescents from the same cities who do not live in public housing. In Rochester, property crime and violence participation rates during adolescence and early adulthood among those in public housing are statistically equivalent to participation rates among those not in public housing. In Pittsburgh, living in public housing during late adolescence and early adulthood, particularly in large housing developments,increases the risk for violent offending, but not for property offending. The current study relies on a relatively small number of subjects in public housing at any single point in time and is based on cross-sectional analyses. Even so, there are several important policy implications that can be derived from this study, given that it moves down a path heretofore largely unexplored. Policy Implications: If replicated, our findings indicate that not all public housing is inhabited disproportionately by those involved in crime; that to develop appropriate responses, it is essential to discover if the perpetrators of violence are residents or trespassers; that policy should target reducing violence specifically and not crime in general; that a modification to housing allocation policies that limits, to the extent possible, placing families with children in late adolescence into large developments might reduce violence perpetrated by residents; that limited resources directed at reducing violence among residents should be targeted at those developments or buildings that actually have high rates of participation in violence among the residents; and that best practices may be derived from developments where violence is not a problem. [source] Making Scents: Improvement of Olfactory Profile after Botulinum Toxin-A Treatment in Healthy IndividualsDERMATOLOGIC SURGERY, Issue 2007MARC HECKMANN MD BACKGROUND The axilla is particularly associated with body odor and putative pheromone production in humans. Although botulinum toxin type A (BT-A) is injected increasingly into the axillary skin to stop excessive sweating, its potential to control body odor is largely unexplored. OBJECTIVE The objective was to measure the impact of BT-A on human axillary odor in an objective and reproducible fashion. METHODS This study was a randomized, double-blind, placebo-controlled trial with 51 healthy volunteers receiving 50 U of BOTOX (Allergan, Inc.) in one axilla and placebo in the other. Odor quality was assessed by treated subjects (questionnaire) as well as by independent raters who were exposed to blinded T-shirt samples. RESULTS No major side effects occurred, and no subject withdrew from the study for medical reasons. Samples from the BT-A,treated side smelled less intense (p<.001) and better (p<.001) according to self-assessments. Likewise, independent raters found the BT-A,treated samples to smell less intense and better (p<.001). They preferred "to work together with the respective person" and found the odor "more erotic" (p<.001). CONCLUSION Side-by-side comparison of odor samples (T-shirt sniff test) by independent raters showed that axillary odor in healthy individuals is significantly more appealing after BT-A injection. [source] CONSENT, COMMODIFICATION AND BENEFIT-SHARING IN GENETIC RESEARCH1DEVELOPING WORLD BIOETHICS, Issue 2 2004DONNA DICKENSON ABSTRACT The global value of the biotechnology industry is now estimated at 17 billion dollars, with over 1300 firms involved as of the year 2000.2 It has been said that ,What we are witnessing is nothing less than a new kind of gold rush, and the territory is the body.' As in previous gold rushes, prospectors are flooding into unexplored and ,wide open' territories from all over the world, with possible ramifications for exploitation of Third World populations. These territories are also the Wild West of bioethics insofar as the law has very little hold on them: existing medical and patent law, such as the Moore and Chakrabarty cases, exert little control over powerful economic interests in both the United States and Europe. In the absence of a unified and consistent law on property in the body, the focus is increasingly on refining the consent approach to rights in human tissue and the human genome, with sensitive and promising developments from the Human Genetics Commission and the Department for International Development consultation on intellectual property. These developments incorporate the views of vulnerable genetic communities such as Native Americans or some Third World populations, and should be welcomed because they recognise the power imbalance between such groups and First World researchers or firms. However, they also highlight the continued tension about what is really wrong with commodifying human tissue or the human genome. Where's the injustice, and can it be solved by a more sophisticated consent procedure? [source] Oda16/Wdr69 is essential for axonemal dynein assembly and ciliary motility during zebrafish embryogenesisDEVELOPMENTAL DYNAMICS, Issue 8 2010Chunlei Gao Abstract In the alga Chlamydomonas reinhardtii, Oda16 functions during ciliary assembly as an adaptor for intraflagellar transport of outer arm dynein. Oda16 orthologs only occur in genomes of organisms that use motile cilia; however, such cilia play multiple roles during vertebrate development and the contribution of Oda16 to their assembly remains unexplored. We demonstrate that the zebrafish Oda16 ortholog (Wdr69) is expressed in organs with motile cilia and retains a role in dynein assembly. Antisense morpholino knockdown of Wdr69 disrupts ciliary motility and results in multiple phenotypes associated with vertebrate ciliopathies. Affected cilia included those in Kupffer's vesicle, where Wdr69 plays a role in generation of asymmetric fluid flow and establishment of organ laterality, and otic vesicles, where Wdr69 is needed to develop normal numbers of otoliths. Analysis of cilium ultrastructure revealed loss of outer dynein arms in morphant embryos. These results support a remarkable level of functional conservation for Oda16/Wdr69. Developmental Dynamics 239:2190,2197, 2010. © 2010 Wiley-Liss, Inc. [source] Skeletal elements in the vertebrate eye and adnexa: Morphological and developmental perspectivesDEVELOPMENTAL DYNAMICS, Issue 5 2006Tamara A. Franz-Odendaal Abstract Although poorly appreciated, the vertebrate eye and adnexa are relatively common sites for skeletogenesis. In many taxa, the skeleton contributes to internal reinforcement in addition to the external housing of the eye (e.g., the circumorbital bones and eyelids). Eyeball elements such as scleral cartilage and scleral ossicles are present within a broad diversity of vertebrates, albeit not therian mammals, and have been used as important models for the study of condensations and epithelial,mesenchymal interactions. In contrast, other elements invested within the eye or its close surroundings remain largely unexplored. The onset and mode of development of these skeletal elements are often variable (early versus late; involving chondrogenesis, osteogenesis, or both), and most (if not all) of these elements appear to share a common neural crest origin. This review discusses the development and distribution of the skeletal elements within and associated with the developing eye and comments on homology of the elements where these are questionable. Developmental Dynamics 235:1244,1255, 2006. © 2006 Wiley-Liss, Inc. [source] Limited phylogeographic structure in the flightless ground beetle, Calathus ruficollis, in southern CaliforniaDIVERSITY AND DISTRIBUTIONS, Issue 5 2007Stylianos Chatzimanolis ABSTRACT The California Floristic Province is home to more than 8000 species of beetles, yet their geographical patterns of supra- and infraspecific diversity remain largely unexplored. In this paper, we investigate the phylogeography and population demographics of a flightless ground beetle, Calathus ruficollis (Coleoptera: Carabidae), in southern California. We sampled 136 specimens from 25 localities divided into 10 populations using a fragment of the mitochondrial cytochrome oxidase I gene. We tested several hypotheses, including the association of geography with particular clades and populations, the degree of differentiation among regions, and the expansion of populations. Parsimony and Bayesian phylogenetic analyses along with nested clade analysis and amova indicate a deep split between the southern Sierra Nevada population and populations south and west. This split corresponds closely to the split between subspecies C. ruficollis ignicollis (southern Sierra Nevada) and C. ruficollis ruficollis. Populations otherwise exhibit limited geographical structure, though Fst values indicate some local differentiation. Mismatch distributions and Fu's Fs indicate range expansion of several populations, suggesting that some structure may have been obscured by recent exchange. The population of C. ruficollis on Santa Cruz Island, which might have been expected to be isolated, shares several haplotypes with mainland populations, appearing to represent multiple colonizations. [source] Escape from natural enemies during climate-driven range expansion: a case studyECOLOGICAL ENTOMOLOGY, Issue 3 2008ROSA MENÉNDEZ Abstract 1.,A major, and largely unexplored, uncertainty in projecting the impact of climate change on biodiversity is the consequence of altered interspecific interactions, for example between parasitoids and their hosts. The present study investigated parasitism in the Brown Argus butterfly, Aricia agestis; a species that has expanded northward in Britain during the last 30 years in association with climate warming. 2.,Aricia agestis larvae suffered lower mortality from parasitoids in newly colonised areas compared with long-established populations. This result was consistent over four consecutive generations (2 years) when comparing one population of each type, and also when several populations within the historical and recently colonised range of the species were compared within a single year. Thus, A. agestis appears to be partially escaping from parasitism as it expands northwards. 3.,Reduced parasitism occurred despite the fact that several of the parasitoid species associated with A. agestis were already present in the newly colonised areas, supported predominantly by an alternative host species, the Common Blue butterfly, Polyommatus icarus. 4.,As the species expand their distributions into areas of increased climatic suitability, invasion fronts may escape from natural enemies, enhancing rates of range expansion. The results suggest that the decoupling of interspecific interactions may allow some species to exploit a wider range of environments and to do so more rapidly than previously thought possible. [source] Ecological implications of plants' ability to tell the timeECOLOGY LETTERS, Issue 6 2009Víctor Resco Abstract The circadian clock (the endogenous mechanism that anticipates diurnal cycles) acts as a central coordinator of plant activity. At the molecular and organism level, it regulates key traits for plant fitness, including seed germination, gas exchange, growth and flowering, among others. In this article, we explore current evidence on the effect of the clock for the scales of interest to ecologists. We begin by synthesizing available knowledge on the effect of the clock on biosphere,atmosphere interactions and observe that, at least in the systems where it has been tested, the clock regulates gas exchange from the leaf to the ecosystem level, and we discuss its implications for estimates of the carbon balance. Then, we analyse whether incorporating the action of the clock may help in elucidating the effects of climate change on plant distributions. Circadian rhythms are involved in regulating the range of temperatures a species can survive and affects plant interactions. Finally, we review the involvement of the clock in key phenological events, such as flowering time and seed germination. Because the clock may act as a common mechanism affecting many of the diverse branches of ecology, our ultimate goal is to stimulate further research into this pressing, yet unexplored, topic. [source] Temporal dynamics within a contemporary latitudinal diversity gradientECOLOGY LETTERS, Issue 9 2008Jonathan A. D. Fisher Abstract Poleward declines in species diversity [latitudinal diversity gradients (LDG)] remain among the oldest and most widespread of macroecological patterns. However, their contemporary dynamics remain largely unexplored even though changing ecological conditions, including global change, may modify LDG and their respective ecosystems. Here, we examine temporal variation within a temperate Northwest Atlantic LDG using 31 years of annual fisheries-independent surveys and explore its dynamics in relation to a dominant climate signal [the wintertime North Atlantic Oscillation (NAO)] that varies interannually and alters the latitudinal gradient of Northwest Atlantic continental shelf bottom water temperatures. We found that the slopes of the annual LDG vary dramatically due to changes in geographic distributions of 100+ species, variations that are concealed within the cumulative, static LDG. These changes are strongly associated with changes in NAO sign and strength. This is the first illustration of temporal dynamics in a contemporary LDG and the first demonstration of the speed at which local environmental variations can alter an LDG. Our findings underscore the need to investigate factors that modify LDG separately from those that contribute to their origins. [source] Leaf herbivory and nutrients increase nectar alkaloidsECOLOGY LETTERS, Issue 8 2006Lynn S. Adler Abstract Correlations between traits may constrain ecological and evolutionary responses to multispecies interactions. Many plants produce defensive compounds in nectar and leaves that could influence interactions with pollinators and herbivores, but the relationship between nectar and leaf defences is entirely unexplored. Correlations between leaf and nectar traits may be mediated by resources and prior damage. We determined the effect of nutrients and leaf herbivory by Manduca sexta on Nicotiana tabacum nectar and leaf alkaloids, floral traits and moth oviposition. We found a positive phenotypic correlation between nectar and leaf alkaloids. Herbivory induced alkaloids in nectar but not in leaves, while nutrients increased alkaloids in both tissues. Moths laid the most eggs on damaged, fertilized plants, suggesting a preference for high alkaloids. Induced nectar alkaloids via leaf herbivory indicate that species interactions involving leaf and floral tissues are linked and should not be treated as independent phenomena in plant ecology or evolution. [source] The wholesale and retail markets of London, 1660,1840ECONOMIC HISTORY REVIEW, Issue 1 2002Colin Smith Markets and marketing are perennial themes in English economic and social history. Yet they remain largely unexplored in relation to London during a period of remarkable growth and change, the long eighteenth century. This article begins to fill that void, by surveying over 70 London produce markets that existed during the period, and identifying patterns in their collective development. It concludes that the physical market place, though ancient in origin, evolved through the ,commercial revolution' as a highly dynamic and diverse institution that played a significant role in London's distribution. [source] The Signalling Role of Municipal Currencies in Local DevelopmentECONOMICA, Issue 288 2005Rajshri Jayaraman The last decade has seen the burgeoning of several hundred local community currency institutions in cities across the world. Although residents of these communities claim that local currency promotes local development, how it does so has hitherto been unexplored. We argue that the introduction of a municipal currency may serve as a signal of demand for local goods. Where demand uncertainty deters firms from investing in more productive technologies, such a signal improves the chances that technology choice will be optimal. The introduction of a local currency therefore always improves ex ante efficiency and may lead to ex post efficiency, with strictly higher levels of productivity and welfare. [source] Toxicity of the molybdate anion in soil is partially explained by effects of the accompanying cation or by soil pHENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Jurgen Buekers Abstract Previous studies have shown that toxicity of cationic trace metals in soil is partially confounded by effects of the accompanying anions. A similar assessment is reported here for toxicity of an oxyanion, i.e., molybdate (MoO), the soil toxicity of which is relatively unexplored. Solubility and toxicity were compared between the soluble sodium molybdate (Na2MoO4) and the sparingly soluble molybdenum trioxide (MoO3). Confounding effects of salinity were excluded by referencing the Na2MoO4 effect to that of sodium chloride (NaCl). The pH decrease from the acid MoO3 amendment was equally referenced to a hydrochloric (HCl) treatment or a lime-controlled MoO3 treatment. The concentrations of molybdenum (Mo) in soil solution or calcium chloride (CaCl2) 0.01,M extracts were only marginally affected by either MoO3 or Na2MoO4 as an Mo source after 10 to 13 days of equilibration. Effects of Mo on soil nitrification were fully confounded by associated changes in salinity or pH. Effects of Mo on growth of wheat seedlings (Triticum aestivum L) were more pronounced than those on nitrification, and toxicity thresholds were unaffected by the form of added Mo. The Mo thresholds for wheat growth were not confounded by pH or salinity at incipient toxicity. It is concluded that oxyanion toxicity might be confounded in relatively insensitive tests for which reference treatments should be included. Environ. Toxicol. Chem. 2010;29:1274,1278. © 2010 SETAC [source] Experimental epileptology before 1900EPILEPSIA, Issue 3 2009Mervyn J. Eadie Summary The available English and other major Western European language literature was reviewed to assess the stage of development of experimental epileptology prior to the end of the 19th Century. The relevant investigations had been carried out in animals of various species employing a number of methods of evoking convulsive seizures, mainly mechanical, electrical or chemical stimulation or surgical removal of parts of the cerebral cortex. The studies had produced some conflicting data but (i) allowed the development of a number of reasonably satisfactory experimental models of convulsive epileptic seizures (ii) confirmed that such epileptic seizures arose from the cerebral cortex, and (iii) suggested that for local onset epileptic seizures to become generalised tonic-clonic ones, the opposite motor cortex and probably a brain stem, possibly pontine, centre needed to be involved. No generally acceptable animal model of chronic epilepsy had been developed, and the non-motor manifestations of epileptic seizures were still largely unexplored experimentally. Nevertheless, the pre-1900 investigations not only laid the foundations for the 20th Century expansion of experimental studies on epileptogenesis but also advanced the understanding of epileptic seizure production. [source] Pro-eating disorder websites: users' opinionsEUROPEAN EATING DISORDERS REVIEW, Issue 3 2007Emese Csipke Abstract The phenomenon of ,pro-eating disorder' websites remains relatively unexplored by researchers in published formats. Supporters of the sites claim beneficial effects but health professionals worry that the sites propagate disordered behaviours. The present study addressed visitor characteristics and perceived impact of visits. A 24-item questionnaire supplemented with the Eating Attitudes Test-26 (EAT-26) was developed and posted on the website of the UK mental health charity SANE. Participants who interacted with others on the sites and sought emotional support reported improved mental state after visiting, and for them, evidence was found of reduced impact from potentially damaging content. ,Silent browsing' in order to sustain a disorder was found to be mainly harmful. ,Silent browsers' may be particularly vulnerable to a worsening of their symptoms in the absence of beneficial effects from emotional support, but those who interact and find support could face a danger of a different sort. © 2007 John Wiley & Sons, Ltd and Eating Disorders Association. [source] Distinct expression of C1q-like family mRNAs in mouse brain and biochemical characterization of their encoded proteinsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2010Takatoshi Iijima Abstract Many members of the C1q family, including complement C1q and adiponectin, and the structurally related tumor necrosis factor family are secreted and play crucial roles in intercellular signaling. Among them, the Cbln (precerebellin) and C1q-like (C1ql) subfamilies are highly and predominantly expressed in the central nervous system. Although the Cbln subfamily serve as essential trans-neuronal regulators of synaptic integrity in the cerebellum, the functions of the C1ql subfamily (C1ql1,C1ql4) remain unexplored. Here, we investigated the gene expression of the C1ql subfamily in the adult and developing mouse brain by reverse transcriptase-polymerase chain reaction and high-resolution in-situ hybridization. In the adult brain, C1ql1,C1ql3 mRNAs were mainly expressed in neurons but weak expression was seen in glia-like structures in the adult brain. The C1ql1 mRNA was predominantly expressed in the inferior olive, whereas the C1ql2 and C1ql3 mRNAs were strongly coexpressed in the dentate gyrus. Although the C1ql1 and C1ql3 mRNAs were detectable as early as embryonic day 13, the C1ql2 mRNA was observed at later embryonic stages. The C1ql1 mRNA was also expressed transiently in the external granular layer of the cerebellum. Biochemical characterization in heterologous cells revealed that all of the C1ql subfamily proteins were secreted and they formed both homomeric and heteromeric complexes. They also formed hexameric and higher-order complexes via their N-terminal cysteine residues. These results suggest that, like Cbln, the C1ql subfamily has distinct spatial and temporal expression patterns and may play diverse roles by forming homomeric and heteromeric complexes in the central nervous system. [source] Adhesion Characteristics of PDMS Surfaces During Repeated Pull-Off Force Measurements,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Elmar Kroner Abstract To mimic the adhesive effects of gecko toes, artificial surfaces have been manufactured recently using polydimethylsiloxanes (PDMS). However, the effects of repeated contacts on the adhesive properties remain largely unexplored. In this paper we report on the effect of repeated pull-off force measurements on the adhesion behavior of PDMS (polymer kit Sylgard 184, Dow Corning) tested with a borosilicate glass probe. A decrease in pull-off force with increase in number of test cycles is found until a plateau is reached. The initial value and the rate of change in pull-off force strongly depend on the sample preparation procedure, including curing time and cross-linking. It is proposed that the behavior is due to steady coverage of the probe with free oligomers. The results are crucial for developing reusable, durable, and residue-free bioinspired adhesives. [source] Antheraea assama Silk Fibroin-Based Functional Scaffold with Enhanced Blood Compatibility for Tissue Engineering Applications,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Naresh Kasoju Abstract The architecture and surface chemistry of a scaffold determine its utility in tissue engineering (TE). Conventional techniques have limitations in fabricating a scaffold with control over both architecture and surface chemistry. To ameliorate this, in this report, we demonstrate the fabrication of an Antheraea assama silk fibroin (AASF)-based functional scaffold. AASF is a non-mulberry variety having superior qualities to mulberry SF and is largely unexplored in the context of TE. First, a 3D scaffold with biomimetic architecture is fabricated. The scaffold is subsequently made blood compatible by modifying the surface chemistry through a simple sulfation reaction. EDX and FTIR analysis demonstrate the successful sulfation of the scaffold. SEM observations reveal that sulfation has no any effect on the scaffold architecture. TGA reveals that it has increased thermal stability. The sulfation reaction significantly improves the overall hydrophilicity of the scaffold, as is evident from the increase in water holding capacity; this possibly enhances the blood compatibility. The enhancement in blood compatibility of the sulfated scaffold is determined from in vitro haemolysis, protein adsorption and platelet adhesion studies. The sulfated scaffold is non-toxic and supports cell adhesion and growth, as revealed by indirect and direct contact-based in vitro cytotoxicity assays. This study reveals that the AASF-based functional scaffold, which has biomimetic architecture and blood-compatible surface chemistry, could be suitable for TE applications. [source] The anatomy of autonomy: Reassessing the autonomy of the European CommissionEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 4 2008JARLE TRONDAL Yet, the factual autonomy of the Commission remains largely unexplored, contributing to contradictory assessments of it. This study reassesses the behavioural autonomy of the Commission, as well as organisational conditions thereof. The article utilises one under-researched laboratory of the Commission: temporary officials (SNEs). SNEs may serve as a crucial test-bed of Commission autonomy due to their ambiguous affiliation towards the Commission. Whereas past studies claim that SNEs have a predominantly intergovernmental behavioural pattern, this study demonstrates that the SNEs blend departmental, epistemic and supranational behavioural dynamics, thereby safeguarding their behavioural autonomy. Understanding Commission autonomy requires that the organisational anatomy of the Commission organisation be carefully considered. The organisational anatomy is measured by considering four independent variables: the organisational composition of the Commission services; organisational incompatibilities across levels of governance; recruitment procedures of Commission officials through a so-called ,submarine' approach; and socialisation dynamics inside the Commission. The autonomy of the Commission is organisationally contingent and not only subject to what has been called ,actors' conspicuous desire for autonomy'. [source] Effects of wetting and drying cycles on in situ soil particle mobilizationEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008S. Majdalani Summary Understanding particle mobilization and transport in soils is a major concern for environmental protection and water resource management as they can act as vectors for sorbing pollutants. In natural soils, the existence of a finite size and renewable pool of dispersible particles has been hypothesized. Even though freeze-thaw and wetting-drying cycles have been identified as possible mechanisms of pool replenishment between rainfall events, to date the underlying phenomena ruling the renewal of particle pools are still largely unexplored. We carried out a series of infiltration-drainage experiments to study systematically the effects of periods without rain (pauses) on in situ particle mobilization in undisturbed soil columns. We found that, for a given column, pause duration between two rainfall events has a major influence on subsequent particle mobilization: the mass of leached particles increases with pause duration until it reaches a maximum (mass for a 200-hours pause is 15 time greater than for a 1-hour pause), and then it decreases for even longer pauses. This behaviour was correlated with soil water content, and can be explained by soil matrix weakening due to differential capillary stresses during drying. The consequences of this finding are important because the 15-fold increase in mass of leached particles, when pause duration is changed from 1 hour to 4 days, might overwhelm variations caused by changes in other parameters such as the ionic strength of the incoming solution or the rainfall intensity. [source] UNCOORDINATED PHYLOGEOGRAPHY OF BORRELIA BURGDORFERI AND ITS TICK VECTOR, IXODES SCAPULARISEVOLUTION, Issue 9 2010Parris T. Humphrey Vector-borne microbes necessarily co-occur with their hosts and vectors, but the degree to which they share common evolutionary or biogeographic histories remains unexplored. We examine the congruity of the evolutionary and biogeographic histories of the bacterium and vector of the Lyme disease system, the most prevalent vector-borne disease in North America. In the eastern and midwestern US, Ixodes scapularis ticks are the primary vectors of Borrelia burgdorferi, the bacterium that causes Lyme disease. Our phylogeographic and demographic analyses of the 16S mitochondrial rDNA suggest that northern I. scapularis populations originated from very few migrants from the southeastern US that expanded rapidly in the Northeast and subsequently in the Midwest after the recession of the Pleistocene ice sheets. Despite this historical gene flow, current tick migration is restricted even between proximal sites within regions. In contrast, B. burgdorferi suffers no barriers to gene flow within the northeastern and midwestern regions but shows clear interregional migration barriers. Despite the intimate association of B. burgdorferi and I. scapularis, the population structure, evolutionary history, and historical biogeography of the pathogen are all contrary to its arthropod vector. In the case of Lyme disease, movements of infected vertebrate hosts may play a larger role in the contemporary expansion and homogenization of the pathogen than the movement of tick vectors whose populations continue to bear the historical signature of climate-induced range shifts. [source] PHYTOPHAGOUS INSECT,MICROBE MUTUALISMS AND ADAPTIVE EVOLUTIONARY DIVERSIFICATIONEVOLUTION, Issue 5 2008Eric M. Janson Adaptive diversification is a process intrinsically tied to species interactions. Yet, the influence of most types of interspecific interactions on adaptive evolutionary diversification remains poorly understood. In particular, the role of mutualistic interactions in shaping adaptive radiations has been largely unexplored, despite the ubiquity of mutualisms and increasing evidence of their ecological and evolutionary importance. Our aim here is to encourage empirical inquiry into the relationship between mutualism and evolutionary diversification, using herbivorous insects and their microbial mutualists as exemplars. Phytophagous insects have long been used to test theories of evolutionary diversification; moreover, the diversification of a number of phytophagous insect lineages has been linked to mutualisms with microbes. In this perspective, we examine microbial mutualist mediation of ecological opportunity and ecologically based divergent natural selection for their insect hosts. We also explore the conditions and mechanisms by which microbial mutualists may either facilitate or impede adaptive evolutionary diversification. These include effects on the availability of novel host plants or adaptive zones, modifying host-associated fitness trade-offs during host shifts, creating or reducing enemy-free space, and, overall, shaping the evolution of ecological (host plant) specialization. Although the conceptual framework presented here is built on phytophagous insect,microbe mutualisms, many of the processes and predictions are broadly applicable to other mutualisms in which host ecology is altered by mutualistic interactions. [source] DIVERSITY IN THE WEAPONS OF SEXUAL SELECTION: HORN EVOLUTION IN THE BEETLE GENUS ONTHOPHAGUS (COLEOPTERA: SCARABAEIDAE)EVOLUTION, Issue 5 2005Douglas J. Emlen Abstract Both ornaments and weapons of sexual selection frequently exhibit prolific interspecific diversity of form. Yet, most studies of this diversity have focused on ornaments involved with female mate choice, rather than on the weapons of male competition. With few exceptions, the mechanisms of divergence in weapon morphology remain largely unexplored. Here, we characterize the evolutionary radiation of one type of weapon: beetle horns. We use partial sequences from four nuclear and three mitochondrial genes to develop a phylogenetic hypothesis for a worldwide sample of 48 species from the dung beetle genus Onthophagus (Coleoptera: Scarabaeidae). We then use these data to test for multiple evolutionary origins of horns and to characterize the evolutionary radiation of horns. Although our limited sampling of one of the world's most species-rich genera almost certainly underestimates the number of evolutionary events, our phylogeny reveals prolific evolutionary lability of these exaggerated sexually selected weapons (more than 25 separate gains and losses of five different horn types). We discuss these results in the context of the natural history of these beetles and explore ways that sexual selection and ecology may have interacted to generate this extraordinary diversity of weapon morphology. [source] PERSPECTIVE: EMBEDDED MOLECULAR SWITCHES, ANTICANCER SELECTION, AND EFFECTS ON ONTOGENETIC RATES: A HYPOTHESIS OF DEVELOPMENTAL CONSTRAINT ON MORPHOGENESIS AND EVOLUTIONEVOLUTION, Issue 5 2003Kathryn D. Kavanagh Abstract The switch between the cell cycle and the progress of differentiation in developmental pathways is prevalent throughout the eukaryotes in all major cell lineages. Disruptions to the molecular signals regulating the switch between proliferative and differentiating states are severe, often resulting in cancer formation (uncontrolled proliferation) or major developmental disorders. Uncontrolled proliferation and developmental disorders are potentially lethal defects in the developing animal. Therefore, natural selection would likely favor a tightly controlled regulatory mechanism to help prevent these fundamental defects. Although selection is usually thought of as a consequence of environmental or ecological influences, in this case the selective force to maintain this molecular switch is internal, manifested as a potentially lethal developmental defect. The morphogenetic consequences of this prevalent, deeply embedded, and tightly controlled mechanistic switch are currently unexplored, however experimental and correlative evidence from several sources suggest that there are important consequences on the control of growth rates and developmental rates in organs and in the whole animal. These observations lead one to consider the possibility of a developmental constraint on ontogenetic rates and morphological evolution maintained by natural selection against cancer and other embryonic lethal defects. [source] SPATIOTEMPORAL REORGANIZATION OF GROWTH RATES IN THE EVOLUTION OF ONTOGENYEVOLUTION, Issue 4 2000Miriam L. Zelditch Abstract. Heterochrony, evolutionary changes in rate or timing of development producing parallelism between ontogeny and phylogeny, is viewed as the most common type of evolutionary change in development. Alternative hypotheses such as heterotopy, evolutionary change in the spatial patterning of development, are rarely entertained. We examine the evidence for heterochrony and heterotopy in the evolution of body shape in two clades of piranhas. One of these is the sole case of heterochrony previously reported in the group; the others were previously interpreted as cases of heterotopy. To compare ontogenies of shape, we computed ontogenetic trajectories of shape by multivariate regression of geometric shape variables (i.e., partial warp scores and shape coordinates) on centroid size. Rates of development relative to developmental age and angles between the trajectories were compared statistically. We found a significant difference in developmental rate between species of Serrasalmus, suggesting that heterochrony is a partial explanation for the evolution of body shape, but we also found a significant difference between their ontogenetic transformations; the direction of the difference between them suggests that heterotopy also plays a role in this group. In Pygocentrus we found no difference in developmental rate among species, but we did find a difference in the ontogenies, suggesting that heterotopy, but not heterochrony, is the developmental basis for shape diversification in this group. The prevalence of heterotopy as a source of evolutionary novelty remains largely unexplored and will not become clear until the search for developmental explanations looks beyond heterochrony. [source] ORIGINAL ARTICLE: Propensity of marine reserves to reduce the evolutionary effects of fishing in a migratory speciesEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 3 2009Erin S. Dunlop Abstract Evolutionary effects of fishing can have unwanted consequences diminishing a fishery's value and sustainability. Reserves, or no-take areas, have been proposed as a management tool for reducing fisheries-induced selection, but their effectiveness for migratory species has remained unexplored. Here we develop an eco-genetic model to predict the effects of marine reserves on fisheries-induced evolution under migration. To represent a stock that undergoes an annual migration between feeding and spawning grounds, we draw model parameters from Atlantic cod (Gadus morhua) in the northern part of its range. Our analysis leads to the following conclusions: (i) a reserve in a stock's feeding grounds, protecting immature and mature fish alike, reduces fisheries-induced evolution, even though protected and unprotected population components mix on the spawning grounds; (ii) in contrast, a reserve in a stock's spawning grounds, protecting only mature fish, has little mitigating effects on fisheries-induced evolution and can sometimes even exacerbate its magnitude; (iii) evolutionary changes that are already underway may be difficult to reverse with a reserve; (iv) directly after a reserve is created or enlarged, most reserve scenarios result in yield losses; and (v) timescale is very important: short-term yield losses immediately after a reserve's creation can give way to long-term gains. [source] Public Diplomacy in Grand StrategyFOREIGN POLICY ANALYSIS, Issue 2 2006BEN D. MOR Despite the growing importance of public diplomacy in current international politics, its practice,and particularly its relationship with hard power,remains largely unexplored by diplomatic or strategic theory. This paper applies a grand-strategic perspective to analyze the challenges of "winning hearts and minds" in the new communications and normative environments. Israel's experience in the second Intifada serves to draw empirically based lessons on the grand-strategic relationship between propaganda and counterterrorist operations. This relationship, the case study shows, is shaped by the close proximity of tactical-level events to the "surface" of grand strategy, to which their effects tend quickly to rise in the new communications environment. In this context, the proactive role of public diplomacy becomes a key to grand-strategic success. [source] Electronic Structure and Geminate Pair Energetics at Organic,Organic Interfaces: The Case of Pentacene/C60 HeterojunctionsADVANCED FUNCTIONAL MATERIALS, Issue 23 2009Stijn Verlaak Abstract Organic semiconductors are characterized by localized states whose energies are predominantly determined by electrostatic interactions with their immediate molecular environment. As a result, the details of the energy landscape at heterojunctions between different organic semiconductors cannot simply be deduced from those of the individual semiconductors, and they have so far remained largely unexplored. Here, microelectrostatic computations are performed to clarify the nature of the electronic structure and geminate pair energetics at the pentacene/C60 interface, as archetype for an interface between a donor molecule and a fullerene electron acceptor. The size and orientation of the molecular quadrupole moments, determined by material choice, crystal orientation, and thermodynamic growth parameters of the semiconductors, dominate the interface energetics. Not only do quadrupoles produce direct electrostatic interactions with charge carriers, but, in addition, the discontinuity of the quadrupole field at the interface induces permanent interface dipoles. That discontinuity is particularly striking for an interface with C60 molecules, which by virtue of their symmetry possess no quadrupole. Consequently, at a pentacene/C60 interface, both the vacuum-level shift and geminate pair dissociation critically depend on the orientation of the pentacene ,-system relative to the adjacent C60. [source] The influence of below-ground herbivory and defoliation of a legume on nitrogen transfer to neighbouring plantsFUNCTIONAL ECOLOGY, Issue 2 2007E. AYRES Summary 1Both foliar and root herbivory can alter the exudation of carbon from plant roots, which in turn can affect nitrogen availability in the soil. However, few studies have investigated the effects of herbivory on N fluxes from roots, which can directly increase N availability in the soil and uptake by neighbouring plants. Moreover, the combined effects of foliar and root herbivory on N fluxes remains unexplored. 2We subjected the legume white clover (Trifolium repens L.) to defoliation (through clipping) and root herbivory (by an obligate root-feeding nematode, Heterodera trifolii Goggart) to examine how these stresses individually, and simultaneously, affected the transfer of T. repens -derived N to neighbouring perennial ryegrass (Lolium perenne L.) plants using 15N stable-isotope techniques. We also examined the effects of defoliation and root herbivory on the size of the soil microbial community and the growth response of L. perenne. 3Neither defoliation nor root herbivory negatively affected T. repens biomass. On the contrary, defoliation increased root biomass (34%) and total shoot production by T. repens (100%). Furthermore, defoliation resulted in a fivefold increase in T. repens -derived 15N recovered in L. perenne roots, and increased the size of the soil microbial biomass (77%). In contrast, root herbivory by H. trifolii slightly reduced 15N transfer from T. repens to L. perenne when T. repens root 15N concentration was included as a covariate, and root herbivory did not affect microbial biomass. Growth of L. perenne was not affected by any of the treatments. 4Our findings demonstrate that defoliation of a common grassland legume can substantially increase the transfer of its N to neighbouring plants by directly affecting below-ground N fluxes. These finding require further examination under field conditions but, given the prevalence of N-limitation of plant productivity in terrestrial ecosystems, increased transfer of N from legumes to non-N-fixing species could alter competitive interactions, with implications for plant community structure. [source] ,Have You Got a Boyfriend or are You Single?': On the Importance of Being ,Straight' in Organizational ResearchGENDER, WORK & ORGANISATION, Issue 3 2006Attila Bruni The article focuses on heterosexuality as a covert feature of organization studies as well as of organizational research. In fact, while organization studies have discussed the gendered and the gendering aspects of organizational practices and organizational theory, the implication of heterosexuality has yet to receive intensive analysis in these fields. And while the mutual and reflexive constitution of the observer and the observed has been the topic of a considerable amount of research, the dimension of (heterosexual) desire in this process of mutual constitution is still largely unexplored. Referring to three different episodes that occurred while the author was doing organizational ethnography, the article suggests that a heterosexual model of desire is called into action both in organizational and research activities and that focusing on it can be an occasion to question not only the gender (and heterosexual) biases of organizational practices but also the way in which gender and sexuality are mobilized while doing research. In particular, on the basis of the concept of cathexis, the article shows how heterosexuality is learnt and enacted as a situated practice and through a variety of processes: performing power, negotiating and displaying that one belongs to an organizational culture, obscuring the hetero-normativity of professional identities and neglecting the emotional engagement that characterizes research activities and that exposes the researcher to an otherwise vulnerable position. [source] | |||||||||||||||||||||||||||||||||||||||||||