2,378 research outputs found
Will climate change increase the risk of plant invasions into mountains?
Mountain ecosystems have been less adversely affected by invasions of non-native plants than most other ecosystems, partially because most invasive plants in the lowlands are limited by climate and cannot grow under harsher high-elevation conditions. However, with ongoing climate change, invasive species may rapidly move upwards and threaten mid-, and then high-elevation mountain ecosystems. We evaluated this threat by modeling the current and future habitat suitability for 48 invasive plant species in Switzerland and New South Wales, Australia. Both regions had contrasting climate interactions with elevation, resulting in possible different responses of species distributions to climate change. Using a species distribution modeling approach that combines data from two spatial scales, we built high-resolution species distribution models (†250 m) that account for the global climatic niche of species and also finer variables depicting local climate and disturbances. We found that different environmental drivers limit the elevation range of invasive species in each of the two regions, leading to region-specific species responses to climate change. The optimal suitability for plant invaders is predicted to markedly shift from the lowland to the montane or subalpine zone in Switzerland, whereas the upward shift is far less pronounced in New South Wales where montane and subalpine elevations are already suitable. The results suggest that species most likely to invade high elevations in Switzerland will be cold-tolerant, whereas species with an affinity to moist soils are most likely to invade higher elevations in Australia. Other plant traits were only marginally associated with elevation limits. These results demonstrate that a more systematic consideration of future distributions of invasive species is required in conservation plans of not yet invaded mountainous ecosystems
α-conotoxin GI triazole-peptidomimetics: potent and stable blockers of a human acetylcholine receptor
The potency and selectivity of conotoxin peptides for neuropathic receptors has made them attractive lead compounds in the development of new therapeutics. Specifically, α-conotoxin GI has been shown to be an unparalleled antagonist of the nicotinic acetylcholine receptor (nAChR). However, as with other peptidic leads, poor protease resistance and the redox instability of the conotoxin scaffold limit bioactivity. To counter this, we have employed the underutilised 1,5-disubstituted 1,2,3-triazole to act as a structural surrogate of the native disulfide bonds. Using an efficient, on-resin ruthenium azide-alkyne cycloaddition (RuAAC), each disulfide bond was replaced in turn and the biological activities quantified. One of the mimetic isomers exhibited a comparable activity to the native toxin, while the other showed no biological effect. The active mimetic isomer 11 was an order of magnitude more stable in plasma than the native GI. The NMR solution structure of the mimetic overlays extremely well with the structure for the native GI demonstrating that the triazole bridge is an exceptional surrogate for the disulfide bridge. Development of this potent and stable mimetic of GI leads us to believe that this strategy will yield many other new conotoxin-inspired probes and therapeutics
Reading Videogames as (authorless) Literature
This article presents the outcomes of research, funded by the Arts and Humanities Research Council in England and informed by work in the fields of new literacy research, gaming studies and the socio-cultural framing of education, for which the videogame L.A. Noire (Rockstar Games, 2011) was studied within the orthodox framing of the English Literature curriculum at A Level (pre-University) and Undergraduate (degree level). There is a plethora of published research into the kinds of literacy practices evident in videogame play, virtual world engagement and related forms of digital reading and writing (Gee, 2003; Juul, 2005; Merchant, Gillen, Marsh and Davies, 2012; Apperley and Walsh, 2012; Bazalgette and Buckingham, 2012) as well as the implications of such for home / school learning (Dowdall, 2006; Jenkins, 2006; Potter, 2012) and for teachersâ own digital lives (Graham, 2012). Such studies have tended to focus on younger children and this research is also distinct from such work in the field in its exploration of the potential for certain kinds of videogame to be understood as 'digital transformations' of conventional âschooledâ literature. The outcomes of this project raise implications of such a conception for a further implementation of a âreframedâ literacy (Marsh, 2007) within the contemporary curriculum of a traditional and conservative âsubjectâ. A mixed methods approach was adopted. Firstly, students contributing to a gamplay blog requiring them to discuss their in-game experience through the âlanguage gameâ of English Literature, culminating in answering a question constructed with the idioms of the subjectâs set text âfinal examinationâ. Secondly, students taught their teachers to play L.A. Noire, with free choice over the context for this collaboration. Thirdly, participants returned to traditional roles in order to work through a set of study materials provided, designed to reproduce the conventions of the âstudy guideâ for literature education. Interviews were conducted after each phase and the outcomes informed a redrafting of the study materials which are now available online for teachers â this being the âpracticalâ outcome of the research (Berger and McDougall, 2012). In the act of inserting the study of L.A. Noire into the English Literature curriculum as currently framed, this research moves, through a practical âimplementationâ beyond longstanding debates around narratology and ludology (Frasca, 2003; Juul, 2005) in the field of game studies (Leaning, 2012) through a direct connection to new literacy studies and raises epistemological questions about âsubject identityâ, informed by Bernstein (1996) and Bourdieu (1986) and the implications for digital transformations of texts for both ideas about cultural value in schooled literacy (Kendall and McDougall, 2011) and the politics of âexpertiseâ in pedagogic relations (Ranciere, 2009, Bennett, Kendall and McDougall, 2012a)
Identification of novel subgroup a variants with enhanced receptor binding and replicative capacity in primary isolates of anaemogenic strains of feline leukaemia virus
<b>BACKGROUND:</b>
The development of anaemia in feline leukaemia virus (FeLV)-infected cats is associated with the emergence of a novel viral subgroup, FeLV-C. FeLV-C arises from the subgroup that is transmitted, FeLV-A, through alterations in the amino acid sequence of the receptor binding domain (RBD) of the envelope glycoprotein that result in a shift in the receptor usage and the cell tropism of the virus. The factors that influence the transition from subgroup A to subgroup C remain unclear, one possibility is that a selective pressure in the host drives the acquisition of mutations in the RBD, creating A/C intermediates with enhanced abilities to interact with the FeLV-C receptor, FLVCR. In order to understand further the emergence of FeLV-C in the infected cat, we examined primary isolates of FeLV-C for evidence of FeLV-A variants that bore mutations consistent with a gradual evolution from FeLV-A to FeLV-C.<p></p>
<b>RESULTS:</b>
Within each isolate of FeLV-C, we identified variants that were ostensibly subgroup A by nucleic acid sequence comparisons, but which bore mutations in the RBD. One such mutation, N91D, was present in multiple isolates and when engineered into a molecular clone of the prototypic FeLV-A (Glasgow-1), enhanced replication was noted in feline cells. Expression of the N91D Env on murine leukaemia virus (MLV) pseudotypes enhanced viral entry mediated by the FeLV-A receptor THTR1 while soluble FeLV-A Env bearing the N91D mutation bound more efficiently to mouse or guinea pig cells bearing the FeLV-A and -C receptors. Long-term in vitro culture of variants bearing the N91D substitution in the presence of anti-FeLV gp70 antibodies did not result in the emergence of FeLV-C variants, suggesting that additional selective pressures in the infected cat may drive the subsequent evolution from subgroup A to subgroup C.<p></p>
<b>CONCLUSIONS:</b>
Our data support a model in which variants of FeLV-A, bearing subtle differences in the RBD of Env, may be predisposed towards enhanced replication in vivo and subsequent conversion to FeLV-C. The selection pressures in vivo that drive the emergence of FeLV-C in a proportion of infected cats remain to be established
Evolution of the Greater Caucasus Basement and Formation of the Main Caucasus Thrust, Georgia
Along the northern margin of the ArabiaâEurasia collision zone in the western Greater Caucasus, the Main Caucasus Thrust (MCT) juxtaposes Paleozoic crystalline basement to the north against Mesozoic metasedimentary and volcaniclastic rocks to the south. The MCT is commonly assumed to be the trace of an active plateâboundary scale structure that accommodates ArabiaâEurasia convergence, but field data supporting this interpretation are equivocal. Here we investigate the deformation history of the rocks juxtaposed across the MCT in Georgia using field observations, microstructural analysis, UâPb and 40Ar/39Ar geochronology, and 40Ar/39Ar and (UâTh)/He thermochronology. Zircon UâPb analyses show that Greater Caucasus crystalline rocks formed in the Early Paleozoic on the margin of Gondwana. Lowâpressure/temperature amphiboliteâfacies metamorphism of these metasedimentary rocks and associated plutonism likely took place during Carboniferous accretion onto the Laurussian margin, as indicated by igneous and metamorphic zircon UâPb ages of ~330â310Â Ma. 40Ar/39Ar ages of ~190â135Â Ma from muscovite in a greenschistâfacies shear zone indicate that the MCT likely developed during Mesozoic inversion and/or rifting of the Caucasus Basin. A Mesozoic 40Ar/39Ar biotite age with release spectra indicating partial resetting and Cenozoic (<40Â Ma) apatite and zircon (UâTh)/He ages imply at least ~5â8Â km of Greater Caucasus basement exhumation since ~10Â Ma in response to ArabiaâEurasia collision. Cenozoic reactivation of the MCT may have accommodated a fraction of this exhumation. However, Cenozoic zircon (UâTh)/He ages in both the hanging wall and footwall of the MCT require partitioning a substantial component of this deformation onto structures to the south.Plain Language SummaryCollisions between continents cause deformation of the Earthâs crust and the uplift of large mountain ranges like the Himalayas. Large faults often form to accommodate this deformation and may help bring rocks once buried at great depths up to the surface of the Earth. The Greater Caucasus Mountains form the northernmost part of a zone of deformation due to the ongoing collision between the Arabian and Eurasian continents. The Main Caucasus Thrust (MCT) is a fault juxtaposing old igneous and metamorphic (crystalline) rocks against younger rocks that has often been assumed to be a major means of accommodating ArabiaâEurasia collision. This study examines the history of rocks along the MCT with a combination of field work, study of microscopic deformation in rocks, and dating of rock formation and cooling. The crystalline rocks were added to the margins of presentâday Eurasia about 330â310 million years ago, and the MCT first formed about 190â135 million years ago. The MCT is likely at most one of many structures accommodating presentâday ArabiaâEurasia collision.Key PointsAmphiboliteâfacies metamorphism and plutonism in the Greater Caucasus basement took place ~330â310Â MaThe Main Caucasus Thrust formed as a greenschistâfacies shear zone during Caucasus Basin inversion and/or rifting (~190â135Â Ma)The Main Caucasus Thrust may have helped facilitate a portion of at least 5â8Â km of basement exhumation during ArabiaâEurasia collisionPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/1/tect21292-sup-0002-2019TC005828-ts01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/2/tect21292-sup-0006-2019TC005828-ts05.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/3/tect21292_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/4/tect21292-sup-0003-2019TC005828-ts02.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/5/tect21292-sup-0005-2019TC005828-ts04.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/6/tect21292.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/7/tect21292-sup-0004-2019TC005828-ts03.pd
When the going gets tough the beautiful get going: aesthetic appeal facilitates task performance.
The current studies examined the effect of aesthetic appeal on performance. According to one hypothesis, appeal would lead to overall decrements or enhancements in performance [e.g. Sonderegger & Sauer, (Applied Ergonomics, 41, 403-410, 2010)]. Alternatively, appeal might influence performance only in problem situations, such as when the task is difficult [e.g. Norman, (2004)]. The predictions of these hypotheses were examined in the context of an icon search-and-localisation task. Icons were used because they are well-defined stimuli and pervasive to modern everyday life. When search was made difficult using visually complex stimuli (Experiment 1), or abstract and unfamiliar stimuli (Experiment 2), icons that were appealing were found more quickly than their unappealing counterparts. These findings show that in a low-level visual processing task, with demand characteristics related to appeal eliminated, appeal can influence performance, especially under duress
3D laser nano-printing on fibre paves the way for super-focusing of multimode laser radiation
Multimode high-power laser diodes suffer from inefficient beam focusing, leading to a focal spot 10â100 times greater than the diffraction limit. This inevitably restricts their wider use in âdirect-diodeâ applications in materials processing and biomedical photonics. We report here a âsuper-focusingâ characteristic for laser diodes, where the exploitation of self-interference of modes enables a significant reduction of the focal spot size. This is achieved by employing a conical microlens fabricated on the tip of a multimode optical fibre using 3D laser nano-printing (also known as multi-photon lithography). When refracted by the conical surface, the modes of the fibre-coupled laser beam self-interfere and form an elongated narrow focus, usually referred to as a âneedleâ beam. The multiphoton lithography technique allows the realisation of almost any optical element on a fibre tip, thus providing the most suitable interface for free-space applications of multimode fibre-delivered laser beams. In addition, we demonstrate the optical trapping of microscopic objects with a super-focused multimode laser diode beam thus rising new opportunities within the applications sector where lab-on-chip configurations can be exploited. Most importantly, the demonstrated super-focusing approach opens up new avenues for the âdirect-diodeâ applications in material processing and 3D printing, where both high power and tight focusing is required
An alternative application to the portuguese agro-industrial residue : wheat straw
The effects of alkaline treatments of the wheat straw with sodium hydroxide were investigated. The optimal condition for extraction of hemicelluloses was found to be with 0.50 mol/l sodium hydroxide at 55 °C for 2 h. This resulted in the release of 17.3% of hemicellulose (% dry starting material), corresponding to the dissolution of 49.3% of the original hemicellulose. The yields were determined by gravimetric analysis and expressed as a proportion of the starting material. Chemical composition and physico-chemical properties of the samples of hemicelluloses were elucidated by a combination of sugar analyses, Fourier transform infrared (FTIR), and thermal analysis. The results showed that the treatments were very effective on the extraction of hemicelluloses from wheat straw and that the extraction intensity (expressed in terms of alkali concentration) had a great influence on the yield and chemical features of the hemicelluloses. The FTIR analysis revealed typical signal pattern for the hemicellulosic fraction in the 1,200â1,000 cmâ1 region. Bands between 1,166 and 1,000 cmâ1 are typical of xylans.Conselho Nacional de
Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)Fundação de Amparo a Pesquisa do Estado de SĂŁo Paulo/Brazil (FAPESP)Fundação para a CiĂȘncia e a Tecnologia (FCT) - SFRH/BPD/26156/2005, SFRH/BPD/26108/200
Recommended from our members
Sulforaphane-enriched extracts from glucoraphanin-rich broccoli exert antimicrobial activity against gut pathogens in vitro and innovative cooking methods increase in vivo intestinal delivery of sulforaphane
Purpose
Studies on broccoli (Brassica oleracea var. italica) indicate beneficial effects against a range of chronic diseases, commonly attributed to their bioactive phytochemicals. Sulforaphane, the bioactive form of glucoraphanin, is formed by the action of the indigenous enzyme myrosinase. This study explored the role that digestion and cooking practices play in bioactivity and bioavailability, especially the rarely considered dose delivered to the colon.
Methods
The antimicrobial activity of sulforaphane extracts from raw, cooked super broccoli and cooked super broccoli plus mustard seeds (as a source myrosinase) was assessed. The persistence of broccoli phytochemicals in the upper gastrointestinal tract was analysed in the ileal fluid of 11 ileostomates fed, in a cross-over design, super broccoli soup prepared with and without mustard seeds.
Results
The raw super broccoli had no antimicrobial activity, except against Bacillus cereus, but cooked super broccoli (with and without mustard seeds) showed considerable antimicrobial activity against various tested pathogens. The recovery of sulforaphane in ileal fluids post soup consumption was < 1% but addition of mustard seeds increased colon-available sulforaphane 6-fold. However, when sulforaphane was extracted from the ileal fluid with the highest sulforaphane content and tested against Escherichia coli K12, no inhibitory effects were observed. Analysis of glucosinolates composition in ileal fluids revealed noticeable inter-individual differences, with six ârespondingâ participants showing increases in glucosinolates after broccoli soup consumption.
Conclusions
Sulforaphane-rich broccoli extracts caused potent antimicrobial effects in vitro, and the consumption of sulforaphane-enriched broccoli soup may inhibit bacterial growth in the stomach and upper small intestine, but not in the terminal ileum or the colon
Entrepreneurship, export orientation and economic growth
In this paper the relationship between a countryâs prevalence of new ventures and its rate of economic growth is investigated, while taking into account new venturesâ export orientation. It is generally acknowledged that new venture creation as well as export activity may both be important strategies for achieving national economic growth. However, to our knowledge no attempt has been made to investigate empirically the role of export-driven new ventures in economic growth. We focus on the national level and use data for a sample of 34 countries over the period 2002â2008. Our results suggest that, on top of a positive relation between entrepreneurial activity in general and subsequent macroeconomic growth, there is an additional positive effect of export-oriented early-stage entrepreneurship in higher-income countries. However, there is no such additional effect in lower-income countries
- âŠ