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Distribution by Scientific Domains

Selected Abstracts

Invasion of Agave species (Agavaceae) in south-east Spain: invader demographic parameters and impacts on native species

Ernesto I. Badano
ABSTRACT Several mechanisms have been proposed to explain the success of invasive species in new environments. A species may become invasive when a new site provides the potential for positive rates of population growth. This may be the case of several Agave species introduced to Spain in the 1940s. In this paper we document factors that promote large increases of populations of these species, and their effects on native plant communities in two sites of SE Spain. Results showed higher rhizome and bulbil production, and higher establishment rates by agaves in sandy soils than in clay soils. In their native habitats, agaves have low establishment rates and sandy soils are rare. This suggests that sandy soils are an opportunity which releases the clonal reproduction of Agave. The effects of agaves on the physiological performance and reproduction of native species were negative, positive or neutral, depending on the size and rooting depth of neighbours. Assemblages of native species growing within Agave stands had lower diversity than non-invaded sites. Our data show that Agave stands have positive growth rates in SE Spain, and suggest that sandy soils are a niche dimension enhancing the invasion in these new habitats. [source]

Transplant Survivorship of Bryophyte Soil Crusts in the Mojave Desert

Christina Cole
Patches of the dominant biological soil crust moss (Syntrichia caninervis) in the Mojave Desert were subjected to transplant experiments to test the survivability of crustal transplantation due to source or destination microhabitat. After a period of 27 months, all the reciprocally transplanted and replanted sections had survived. However, percent cover of the reciprocally transplanted patches declined 20,50% relative to initial cover compared to a decline in cover of 36,52% for the replanted patches. Similarly, shoot density declined an average of 26% in the transplants and replants. Shoot mortality was essentially negligible through the first 21 months of the study and then declining across all treatments to approximately 5,10 dead shoots/cm2. However, this shoot death was also observed in equivalent densities in the host patches, indicative of a community-wide decline in plant health that was probably related to a regional rainfall deficit over this period. A tendency existed for plants moved from a shaded site to have reduced shoot density in the new site, and plants moved into exposed sites lost significantly more cover than plants moved into shaded sites. These seemingly conflicting trends result from one of the transplant treatments, the shaded to exposed, exhibiting a greater loss in shoot density and decline in cover than its reciprocal transplant, exposed to shaded. For soil restoration of disturbed bryophyte crusts, we recommend using as source material both the exposed and the shaded portions of the crust but avoiding moving Syntrichia from a shaded site into an exposed site. [source]

Substance P presynaptically depresses the transmission of sensory input to bronchopulmonary neurons in the guinea pig nucleus tractus solitarii

Shin-ichi Sekizawa
Substance P modulates the reflex regulation of respiratory function by its actions both peripherally and in the CNS, particularly in the nucleus tractus solitarii (NTS), the first central site for synaptic contact of the lung and airway afferent fibres. There is considerable evidence that the actions of substance P in the NTS augment respiratory reflex output, but the precise effects on synaptic transmission have not yet been determined. Therefore, we determined the effects of substance P on synaptic transmission at the first central synapses by using whole-cell voltage clamping in an NTS slice preparation. Studies were performed on second-order neurons in the slice anatomically identified as receiving monosynaptic input from sensory nerves in the lungs and airways. This was done by the fluorescent labelling of terminal boutons after 1,1,-dioctadecyl-3,3,3,,3,-tetra-methylindocarbo-cyanine perchlorate (DiI) was applied via tracheal instillation. Substance P (1.0, 0.3 and 0.1 ,M) significantly decreased the amplitude of excitatory postsynaptic currents (eEPSCs) evoked by stimulation of the tractus solitarius, in a concentration-dependent manner. The decrease was accompanied by an increase in the paired-pulse ratio of two consecutive eEPSCs, and a decrease in the frequency, but not the amplitude, of spontaneous EPSCs and miniature EPSCs, findings consistent with a presynaptic site of action. The effects were consistently and significantly attenuated by a neurokinin-1 (NK1) receptor antagonist (SR140333, 3 ,M). The data suggest a new site of action for substance P in the NTS (NK1 receptors on the central terminals of sensory fibres) and a new mechanism (depression of synaptic transmission) for regulating respiratory reflex function. [source]

Local Knowledge as Trapped Knowledge: Intellectual Property, Culture, Power and Politics

Chidi Oguamanam
Discourses of local knowledge and categories of rights claimants thereto are embroiled in complex conceptual and analytical morass. The conceptual quandary around local knowledge is diversionary from the historically rooted hierarchies of culture, power and politics that have subjugated it. Claims to local knowledge are challenged from several dimensions, including arguments from cultural cosmopolitanism, intellectual property rights and aspects of liberal democratic principles. An interesting new site for this power play is the emergent bioprospecting framework of access and benefit sharing. In this context, sophisticated external intermediaries, who have asymmetrical power relationships with custodians of local knowledge, now constitute a new threat to the genuine aspirations of indigenous and local communities. Recently, local knowledge claims are conflated with propertization of culture raising concerns over the asphyxiation of the public domain. Making the claims or claimants to local knowledge the scapegoats of our troubled public domain undermines the source of the problem. In a way, the current anemic state of our public domain can be blamed on unwholesome expansion of intellectual property and unidirectional appropriation of local knowledge by external interests. The reality of cultural cosmopolitanism requires an intellectual property order that is responsive to the contributions of local knowledge. [source]

Bryozoan populations reflect nutrient enrichment and productivity gradients in rivers

Summary 1. The hypothesis that nutrient enrichment will affect bryozoan abundance was tested using two complementary investigations; a field-based method determining bryozoan abundance in 20 rivers of different nutrient concentrations by deploying statoblast (dormant propagule) traps and an experimental laboratory microcosm study measuring bryozoan growth and mortality. These two methods confirmed independently that increased nutrient concentrations in water promote increases in the biomass of freshwater bryozoans. 2. Statoblasts of the genus Plumatella were recorded in all rivers, regardless of nutrient concentrations, demonstrating that freshwater bryozoans are widespread. Concentrations of Plumatella statoblasts were high in rivers with high nutrient concentrations relative to those with low to moderate nutrient concentrations. Regression analyses indicated that phosphorus concentrations, in particular, significantly influenced statoblast concentrations. 3. Concentrations of Lophopus crystallinus statoblasts were also higher in sites characterised by high nutrient concentrations. Logistic regression analysis revealed that the presence of L. crystallinus statoblasts was significantly associated with decreasing altitude and increasing phosphorus concentrations. This apparently rare species was found in nine rivers (out of 20), seven of which were new sites for L. crystallinus. 4. Growth rates of Fredericella sultana in laboratory microcosms increased with increasing nutrient concentration and high mortality rates were associated with low nutrient concentrations. 5. Our results indicate that bryozoans respond to increasing nutrient concentrations by increased growth, resulting in higher biomasses in enriched waters. We also found that an important component of bryozoan diets can derive from food items lacking chlorophyll a. Finally, bryozoans may be used as independent proxies for inferring trophic conditions, a feature that may be especially valuable in reconstructing historical environments by assessing the abundance of statoblasts in sediment cores. [source]

Geomorphology, site distribution, and Paleolithic settlement dynamics of the Ma'aloula region, Damascus Province, Syria

Andrey E. Dodonov
This survey of the geology, geomorphology, and Paleolithic archaeology of a 300 km2 area in Damascus Province, Syria, focused around the villages of Ma'aloula and Jaba'deen. The study resulted in the definition of seven geomorphological zones that trend northeast,southwest, parallel to the prevailing geological features of the region. The zones span a broad range of elevations, from a dry lake bed in the Jeiroud Basin (ca. 800 m) to the peaks of the Anti-Lebanon Mountains (ca. 2350 m). The research focused on assessing the geological and paleoenvironmental history of the region as a backdrop for 500,000 years of Paleolithic settlement. Among the 618 archaeological sites documented thus far, all major archaeological periods from the Lower Paleolithic through the Epipaleolithic are represented. Most abundant are occurrences of the Levalloisian Middle Paleolithic, with 255 new sites documented. Nine Neolithic sites were also included in the survey. The distribution of sites varies during the Paleolithic and reflects the availability of resources, especially of flint and water, as well as the spatial patterns of erosion and deposition on the ancient land surfaces. 2007 Wiley Periodicals, Inc. [source]

Archaeological site distribution by geomorphic setting in the southern lower Cuyahoga River Valley, northeastern Ohio: Initial observations from a GIS database

Andrew Bauer
In this study, we compiled unpublished archival documentation of archaeological site locations from the southern part of the Cuyahoga River Valley in northeastern Ohio, USA, registered at the State of Ohio Historic Preservation Office into a Geographic Information Systems (GIS) database. Using digitized soil shapefiles to generate a geomorphic data layer, we assessed the spatial and temporal distribution of 79 known archaeological sites by landform association. This digital compilation indicates that Woodland period, Late Prehistoric, and Historic sites occur in most geomorphic settings along the river valley. In contrast, Paleoindian and Archaic sites only occur on Wisconsinan cut terraces and in upland interfluve settings, indicating that most of these documented sites are in primary contexts and have not been reworked. We discuss the distribution of archaeological sites in the study region as a function of various factors, including cultural activities, taphonomic processes, landform development, and the nature and extent of the original archaeological surveys. Observed spatial patterns of known sites clearly reflect local geomorphological controls; artifactual contexts from the earlier prehistoric periods are underrepresented in the database. We conclude that additional site surveys, as well as the excavation and documentation of new sites in this part of Ohio, are required to understand local prehistoric economies and to ascertain patterns of culturally mediated land use. 2004 Wiley Periodicals, Inc. [source]

Efficient allocation of resources to prevent HIV infection among injection drug users: the Prevention Point Philadelphia (PPP) needle exchange program

Zo K. Harris
Abstract The objective of this study is to determine the allocation of resources within a multi-site needle exchange program (NEP) that achieves the largest possible reduction in new HIV infections at minimum cost. We present a model that relates the number of injection drug user (IDU) clients and the number of syringes exchanged per client to both the costs of the NEP and the expected reduction in HIV infections per unit time. We show that cost-effective allocation within a multi-site NEP requires that sites be located where the density of IDUs is highest, and that the number of syringes exchanged per client be equal across sites. We apply these optimal allocation rules to a specific multi-site needle exchange program, Prevention Point Philadelphia (PPP). This NEP, we find, needs to add 2 or 3 new sites in neighborhoods with the highest density of IDU AIDS cases, and to increase its total IDU client base by about 28%, from approximately 6400 to 8200 IDU clients. The case-study NEP also needs to increase its hours of operation at two existing sites, where the number of needles distributed per client is currently sub-optimal, by 50%. At the optimal allocation, the estimated cost per case of HIV averted would be $2800 (range $2300,$4200). Such a favorable cost-effectiveness ratio derives primarily from PPP's low marginal costs per distributed needle. Copyright 2005 John Wiley & Sons, Ltd. [source]

Globalized Horticulture: The Formation and Global Integration of Export Grape Production in North East Brazil

In horticulture contemporary globalization is associated with (at least) two connected processes , the concentration, centralization and expanding reach of global retailers and the emergence of numerous new sites of export horticulture specializing in fresh fruit and vegetable production aimed at metropolitan markets. Whilst there have been numerous studies about developmental impacts, conditions of labour, and producers' upgrading strategies within this new context, few studies give much, if any, space to explaining and analyzing the processes through which these new regions have come into being. This article provides a detailed account of the emergence and global integration of one of these new sites , the So Francisco valley grape branch in North East Brazil, within the context of the wider regional fruiticulture sector. It focuses on state activities and incentives, the provenance of grape producers and their organizations, and grape branch composition. [source]

Risk factors associated with mortalities attributed to infectious salmon anaemia virus in New Brunswick, Canada

K L Hammell
Abstract Outbreaks of unexplained mortalities attributed to infectious salmon anaemia (ISA) were examined in the 1996 year class of Atlantic salmon in three regions of New Brunswick, Canada. A total of 218 net pens at 14 sites deemed to have been exposed to ISA virus (ISAV) were surveyed for mortality records and management, environmental and host characteristics. Based on definitions of mortality patterns, clinical ISA disease outbreaks occurred in 106 net pens. There were eight sites in which >50% of net pens experienced ISA outbreaks during the study period. Factors related to their potential role in transmission of virus to new sites or new net pens at the same site were identified as sea lice vectors, divers visiting multiple sites, sites belonging to companies with more than one site, exposure to other year classes at the site, and proximity to other infected net pens. Host resistance factors associated with greater risk of outbreaks were identified as larger groupings, general health following smolt transfer, stressful husbandry procedures during growout, and health or productivity during colder water periods. Despite very close proximity between sites, modification of these management factors would probably influence the severity of mortalities caused by ISAV. [source]

Trends in savanna structure and composition along an aridity gradient in the Kalahari

R.J. Scholes
Abstract. The Kalahari sand sheet occupies 2.5 million ha in southern Africa. It is an area with relatively similar deep aeolian soils, and a strong south to north gradient in rainfall, from 200 to 1000 mm mean annual precipitation (MAP) in the region studied. This provides an excellent basis for gradient studies at the subcontinental scale. This paper briefly reviews the literature on the vegetation of the Kalahari and describes the vegetation structure and composition at 11 new sites. There is a clear gradient in woody plant biomass (as indexed by basal area) from south to north. Above the minimum level of 200 mm MAP, the woody basal area increases at a rate of ca. 2.5 m2.ha -1 per 100 mm MAP. Mean maximum tree height also increases along the gradient, reaching 20 m at ca. 800 mm MAP. The number of species to contribute > 95% of the woody basal area increases from one at 200 mm to 16 at 1000 mm MAP. Members of the Mimosaceae (mainly Acacia) dominate the tree layer up to 400 mm MAP. They are replaced by either the Combretaceae (Combretum or Terminalia) or Colophospermum mopane of the Caesalpinaceae between 400 and 600 mm MAP, and by other representatives of the Caesalpinaceae above 600 mm MAP. The vegetation is largely deciduous up to 1000 mm MAP, except for species that apparently have access to groundwater, which may be locally dominant above about 600 mm MAP. [source]

Conjugation mediates transfer of the Ll.LtrB group II intron between different bacterial species

Kamila Belhocine
Summary Some self-splicing group II introns (ribozymes) are mobile retroelements. These retroelements, which can insert themselves into cognate intronless alleles or ectopic sites by reverse splicing, are thought to be the evolutionary progenitors of the widely distributed eukaryotic spliceosomal introns. Lateral or horizontal transmission of introns (i.e. between species), although never experimentally demonstrated, is a well-accepted model for intron dispersal and evolution. Horizontal transfer of the ancestral bacterial group II introns may have contributed to the dispersal and wide distribution of spliceosomal introns present in modern eukaryotic genomes. Here, the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis was used as a model system to address the dissemination of introns in the bacterial kingdom. We report the first experimental demonstration of horizontal transfer of a group II intron. We show that the Ll.LtrB group II intron, originally discovered on an L. lactis conjugative plasmid (pRS01) and within a chromosomally located sex factor in L. lactis 712, invades new sites using both retrohoming and retrotransposition pathways after its transfer by conjugation. Ll.LtrB lateral transfer is shown among different L. lactis strains (intraspecies) (retrohoming and retrotransposition) and between L. lactis and Enterococcus faecalis (interspecies) (retrohoming). These results shed light on long-standing questions about intron evolution and propagation, and demonstrate that conjugation is one of the mechanisms by which group II introns are, and probably were, broadly disseminated between widely diverged organisms. [source]

Astronomical site selection: on the use of satellite data for aerosol content monitoring

A. M. Varela
ABSTRACT The main goal of this work is to analyse new approaches to the study of the properties of astronomical sites. In particular, satellite data measuring aerosols have recently been proposed as a useful technique for site characterization and searching for new sites to host future very large telescopes. Nevertheless, these data need to be critically considered and interpreted in accordance with the spatial resolution and spectroscopic channels used. In this paper, we have explored and retrieved measurements from satellites with high spatial and temporal resolutions and concentrated on channels of astronomical interest. The selected data sets are the Ozone Monitoring Instrument on board the NASA Aura satellite and the Moderate Resolution Imaging Spectroradiometer on board the NASA Terra and Aqua satellites. A comparison of remote-sensing and in situ techniques is discussed. As a result, we find that aerosol data provided by satellites up to now are not reliable enough for aerosol site characterization, and in situ data are required. [source]

Increase in mate availability without loss of self-incompatibility in the invasive species Senecio inaequidens (Asteraceae)

OIKOS, Issue 2 2007
Lucile Lafuma
The evolution of the strength of self-incompatibility in Senecio inaequidens, a native of South Africa was investigated in relation to its invasion in Europe. Levels of self-incompatibility were estimated with hand-pollinations in five populations in greenhouse conditions. One population came from the native range of the species and four populations were sampled in Europe from two independent transects of colonization with old and recent populations. Contrary to Baker's law predictions, our results suggest that the species has a sporophytic self-incompatible system maintained in all populations. We suggest that the ability of S. inaequidens to colonize new sites with a self-incompatibility system is promoted by its ecological characteristics (perenniality, extended reproductive period, massive seed production, generalist pollinators). In addition, we found that mate availability was increased (1) in the introduced range compared to the native range, (2) in marginal versus central European populations. Possible explanations for this surprising result are discussed. [source]

Taking Constitutionalism Beyond the State

Neil Walker
In recent years, the idea that constitutional modes of government are exclusive to states has become the subject both of sustained challenge and of strong defence. This is due to the development at new regional and global sites of decision-making capacities of a scale and intensity often associated with the demand for constitutional governance at state level, to the supply at these same new sites of certain regulatory institutions and practices of a type capable of being viewed as meeting the demand for constitutional governance, as well as to a growing debate over whether and in what ways these developments in decision-making capacity and regulatory control should be coded and can be constructively engaged with in explicitly constitutional terms. The aim of the article is threefold. It asks why taking the idea and associated ethos and methods of constitutionalism ,beyond the state' might be viewed as a significant and controversial innovation, and so in need of explanation and justification , a question that requires us to engage with the definition of constitutionalism and with the contestation surrounding that definition. Secondly, taking account of the various arguments that lie behind these definitional concerns, it attempts to develop a scheme for understanding certain key features of constitutionalism and of its post-state development that is able to command broad agreement. Thirdly, and joining the concerns of the first two sections, it seeks to identify the key current tensions , or antinomies , surrounding the growth of post-state constitutionalism with a view to indicating what is at stake in the future career of that concept. [source]

Risk and panic in late modernity: implications of the converging sites of social anxiety

Sean P. Hier
ABSTRACT Comparing moral panic with the potential catastrophes of the risk society, Sheldon Ungar contends that new sites of social anxiety emerging around nuclear, medical, environmental and chemical threats have thrown into relief many of the questions motivating moral panic research agendas. He argues that shifting sites of social anxiety necessitate a rethinking of theoretical, methodological and conceptual issues related to processes of social control, claims making and general perceptions of public safety. This paper charts an alternative trajectory, asserting that analytic priority rests not with an understanding of the implications of changing but converging sites of social anxiety. Concentrating on the converging sites of social anxiety in late modernity, the analysis forecasts a proliferation of moral panics as an exaggerated symptom of the heightened sense of uncertainty purported to accompany the ascendency of the risk society. [source]

Distribution and abundance of sacred monkeys in Igboland, southern Nigeria

Lynne R. Baker
Abstract Although primates are hunted on a global scale, some species are protected against harassment and killing by taboos or religious doctrines. Sites where the killing of sacred monkeys or the destruction of sacred groves is forbidden may be integral to the conservation of certain species. In 2004, as part of a distribution survey of Sclater's guenon (Cercopithecus sclateri) in southern Nigeria, we investigated reports of sacred monkeys in the Igbo-speaking region of Nigeria. We confirmed nine new sites where primates are protected as sacred: four with tantalus monkeys (Chlorocebus tantalus) and five with mona monkeys (Cercopithecus mona). During 2004,2006, we visited two communities (Akpugoeze and Lagwa) previously known to harbor sacred populations of Ce. sclateri to estimate population abundance and trends. We directly counted all groups and compared our estimates with previous counts when available. We also estimated the size of sacred groves and compared these with grove sizes reported in the literature. The mean size of the sacred groves in Akpugoeze (2.06,ha, n=10) was similar to others in Africa south of the Sahel, but larger than the average grove in Lagwa (0.49,ha, n=15). We estimated a total population of 124 Sclater's monkeys in 15 groups in Lagwa and 193 monkeys in 20 groups in Akpugoeze. The Akpugoeze population was relatively stable over two decades, although the proportion of infants declined, and the number of groups increased. As Sclater's monkey does not occur in any official protected areas, sacred populations are important to the species' long-term conservation. Despite the monkeys' destruction of human crops, most local people still adhere to the custom of not killing monkeys. These sites represent ideal locations in which to study the ecology of Sclater's monkey and human,wildlife interactions. Am. J. Primatol. 71:574,586, 2009. 2009 Wiley-Liss, Inc. [source]

Collective Intelligence in Design

Christopher Hight
Abstract In their introduction to this issue, Christopher Hight and Chris Perry define the idea of collective intelligence in its relationship to design practice and to broader technological and social formations. First they suggest a reformulation of practices around networked communication infrastructures as conduits for the new orchestrations of power that Antonio Negri and Michael Hardt detailed in their books Empire and Multitude. They then describe how such practices are often involved in the development of responsive sensing environments as new sites for manifesting the social organisations and communities made possible via telecommunications and the Internet. Lastly, they address how traditional boundaries of design disciplines and knowledge, from architecture to programming, are opening into complex co-minglings of their respective isolated ,intelligences' into collectives capable of engaging these new sites, new briefs and new sorts of projects. Copyright 2006 John Wiley & Sons, Ltd. [source]

Small-scale spatial dynamics of vegetation in a grazed Uruguayan grassland

Abstract We explored the small-scale plant species mobility in a subhumid native grassland subjected to grazing by cattle in south-western Uruguay. We established four permanent plots of 40 40 cm, divided in 16 16 cells. In each cell, the presence of species was seasonally recorded for 2 years and annually recorded for 4 years. By nesting the cells, we studied the mobility at different scales, from 6.25 cm2 to 400 cm2. At each scale we measured species richness, cumulative richness and the turnover rates of the dominant species. We found that the cumulative species richness was an increasing power function, with higher accumulation rates with smaller spatial scale. Although species richness showed seasonal fluctuations, the mean species richness was constant during the study period. We detected significant spatio-temporal variability in mobility patterns among species. Certain species showed a high capacity to colonize new sites, whereas other species rotate among sites that they previously occupied. Grazed communities in Uruguayan Campos are structured as a dense matrix of perennials grasses and forbs, where vegetative propagation is the main form of growth of the species. The small-scale dynamics and the high variability in the mobility characteristics could be linked with the diversity of growth forms and spatial strategies of the species in this community. We believe that a high degree of small-scale spatial dynamics contribute to explain the species coexistence and the apparent stability of communities at local scales. [source]

N -Acyl amino acids and N -acyl neurotransmitter conjugates: neuromodulators and probes for new drug targets

Mark Connor
The myriad functions of lipids as signalling molecules is one of the most interesting fields in contemporary pharmacology, with a host of compounds recognized as mediators of communication within and between cells. The N -acyl conjugates of amino acids and neurotransmitters (NAANs) have recently come to prominence because of their potential roles in the nervous system, vasculature and the immune system. NAAN are compounds such as glycine, GABA or dopamine conjugated with long chain fatty acids. More than 70 endogenous NAAN have been reported although their physiological role remains uncertain, with various NAAN interacting with a low affinity at G protein coupled receptors (GPCR) and ion channels. Regardless of their potential physiological function, NAAN are of great interest to pharmacologists because of their potential as flexible tools to probe new sites on GPCRs, transporters and ion channels. NAANs are amphipathic molecules, with a wide variety of potential fatty acid and headgroup moieties, a combination which provides a rich source of potential ligands engaging novel binding sites and mechanisms for modulation of membrane proteins such as GPCRs, ion channels and transporters. The unique actions of subsets of NAAN on voltage-gated calcium channels and glycine transporters indicate that the wide variety of NAAN may provide a readily exploitable resource for defining new pharmacological targets. Investigation of the physiological roles and pharmacological potential of these simple lipid conjugates is in its infancy, and we believe that there is much to be learnt from their careful study. [source]