15,015 research outputs found
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Digital poverty in Margate: a study of two hyperlocal communities
This report presents the findings of an in-depth, qualitative study of digital poverty from the perspectives of two hyperlocal communities in the UK seaside town of Margate. Specifically, the study examines members of Margate’s Roma community and its Creative Diaspora, drawing from interviews with individuals from these communities, in order to better understand specific lived experiences of digital poverty within the changing context of Margate as a place. The analysis is presented under three key headings: skills, productivity, and infrastructure.The British Academ
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Can a native rodent species limit the invasive potential of a non-native rodent species in tropical agroforest habitats?
BACKGROUND
Little is known about native and non-native rodent species interactions in complex tropical agro-ecosystems. We hypothesised that the native non-pest rodent Rattus everetti may be competitively dominant over the invasive pest rodent Rattus tanezumi within agroforests. We tested this experimentally by using pulse removal for three consecutive months to reduce populations of R. everetti in agroforest habitat and assessed over 6-months the response of R. tanezumi and other rodent species.
RESULTS
Following removal, R. everetti individuals rapidly immigrated into removal sites. At the end of the study period, R. tanezumi were larger and there was a significant shift in their microhabitat use with respect to the use of ground vegetation cover following the perturbation of R. everetti. Irrespective of treatment, R. tanezumi selected microhabitat with less tree canopy cover, indicative of severely disturbed habitat, whereas, R. everetti selected microhabitat with a dense canopy.
CONCLUSION
Our results suggest that sustained habitat disturbance in agroforests favours R. tanezumi, whilst the regeneration of agroforests towards a more natural state would favour native species and may reduce pest pressure in adjacent crops. In addition, the rapid recolonisation of R. everetti suggests this species would be able to recover from non-target impacts of short-term rodent pest control
The Discovery of XY Sex Chromosomes in a \u3cem\u3eBoa\u3c/em\u3e and \u3cem\u3ePython\u3c/em\u3e
For over 50 years, biologists have accepted that all extant snakes share the same ZW sex chromosomes derived from a common ancestor [1, 2, 3], with different species exhibiting sex chromosomes at varying stages of differentiation. Accordingly, snakes have been a well-studied model for sex chromosome evolution in animals [1, 4]. A review of the literature, however, reveals no compelling support that boas and pythons possess ZW sex chromosomes [2, 5]. Furthermore, phylogenetic patterns of facultative parthenogenesis in snakes and a sex-linked color mutation in the ball python (Python regius) are best explained by boas and pythons possessing an XY sex chromosome system [6, 7]. Here we demonstrate that a boa (Boa imperator) and python (Python bivittatus) indeed possess XY sex chromosomes, based on the discovery of male-specific genetic markers in both species. We use these markers, along with transcriptomic and genomic data, to identify distinct sex chromosomes in boas and pythons, demonstrating that XY systems evolved independently in each lineage. This discovery highlights the dynamic evolution of vertebrate sex chromosomes and further enhances the value of snakes as a model for studying sex chromosome evolution
Inherent tracers for carbon capture and storage in sedimentary formations: composition and applications
Inherent tracers - the “natural” isotopic and trace gas composition of captured CO₂ streams – are potentially powerful tracers for use in CCS technology. This review outlines for the first time the expected carbon isotope and noble gas compositions of captured CO₂ streams from a range of feedstocks, CO₂-generating processes and carbon capture techniques. The C-isotope composition of captured CO₂ will be most strongly controlled by the feedstock, but significant isotope fractionation is possible during capture; noble gas concentrations will be controlled by the capture technique employed. Comparison with likely baseline data suggests that CO₂ generated from fossil fuel feedstocks will often have δ13C distinguishable from storage reservoir CO₂. Noble gases in amine-captured CO₂ streams are likely to be low concentration, with isotopic ratios dependant on the feedstock, but CO₂ captured from oxyfuel plants may be strongly enriched in Kr and Xe which are potentially valuable subsurface tracers. CO₂ streams derived from fossil fuels will have noble gas isotope ratios reflecting a radiogenic component that will be difficult to distinguish in the storage reservoir, but inheritance of radiogenic components will provide an easily recognisable signature in the case of any unplanned migration into shallow aquifers or to the surface
Head-on collisions of binary white dwarf--neutron stars: Simulations in full general relativity
We simulate head-on collisions from rest at large separation of binary white
dwarf -- neutron stars (WDNSs) in full general relativity. Our study serves as
a prelude to our analysis of the circular binary WDNS problem. We focus on
compact binaries whose total mass exceeds the maximum mass that a cold
degenerate star can support, and our goal is to determine the fate of such
systems. A fully general relativistic hydrodynamic computation of a realistic
WDNS head-on collision is prohibitive due to the large range of dynamical time
scales and length scales involved. For this reason, we construct an equation of
state (EOS) which captures the main physical features of NSs while, at the same
time, scales down the size of WDs. We call these scaled-down WD models
"pseudo-WDs (pWDs)". Using pWDs, we can study these systems via a sequence of
simulations where the size of the pWD gradually increases toward the realistic
case. We perform two sets of simulations; One set studies the effects of the NS
mass on the final outcome, when the pWD is kept fixed. The other set studies
the effect of the pWD compaction on the final outcome, when the pWD mass and
the NS are kept fixed. All simulations show that 14%-18% of the initial total
rest mass escapes to infinity. All remnant masses still exceed the maximum rest
mass that our cold EOS can support (1.92 solar masses), but no case leads to
prompt collapse to a black hole. This outcome arises because the final
configurations are hot. All cases settle into spherical, quasiequilibrium
configurations consisting of a cold NS core surrounded by a hot mantle,
resembling Thorne-Zytkow objects. Extrapolating our results to realistic WD
compactions, we predict that the likely outcome of a head-on collision of a
realistic, massive WDNS system will be the formation of a quasiequilibrium
Thorne-Zytkow-like object.Comment: 24 pages, 14 figures, matches PRD published version, tests of HRSC
schemes with piecewise polytropes adde
Tribology: The Story of Lubrication and Wear
Topics addressed include: lubrication and design of high speed rolling element bearings, high speed gears, and traction drives
Life cycle assessment of lignocellulosic biomass pretreatment methods in biofuel production
Purpose:
In converting lignocellulosic biomass into biofuel, a pretreatment stage is required in order to make the biomass more readily available for the transformation. There are numerous pretreatment techniques that can be chosen, which are broken down into four categories: chemical, physical, physicochemical, and biological. The aim of this work is to provide a new assessment for some of the emerging technologies using life cycle assessment (LCA) combined with an analysis of the overall product yield.
Methods:
Using literature data, an LCA of four different pretreatment methods was carried out. Liquid hot water (LHW), steam explosion (SE), dilute acid (DA), and organosolv (OS) were chosen as the most common techniques with high scalability potential. Models were constructed using GaBi software. A cradle-to-gate analysis was selected with a common model of the corn stover growth and harvesting cycle being combined with the individual models for each pretreatment. Four impact categories were analyzed, and a selection has been discussed based on relevance to the biofuel production process.
Results and discussion:
In nearly all of the impact categories, DA performs the worst due to the length of the process (12 h) and the amount of electricity required to elevate the temperature to 60 °C for that time period. In many of the other categories, the remaining three pretreatments perform comparably to each other with the exception of LHW which has significantly reduced CO2 emissions. LHW has slightly higher water depletion rates than both SE and OS, which is to be expected given the nature of the process. In terms of product yield, LHW produced twice as much total sugar than any of the other processes.
Conclusions:
The project concluded that while LHW and SE are viable options for the pretreatment of biomass, LHW is the most suitable technique for the pretreatment of corn stover. This pretreatment was environmentally friendly as it produced the lowest CO2 emissions, aligning with the main objective behind developing biofuels from agricultural residues. The process was also technically the most effective as it resulted in the highest sugar yields.
Methods: Using literature data, an LCA of four different pretreatment
methods was carried out. Liquid hot water (LHW), steam explosion (SE), dilute acid (DA), and organosolv (OS) were chosen as the most common techniques with high scalability potential. Models were constructed using GaBi software. A cradle-to-gate analysis was selected with a common model of the corn stover growth and harvesting cycle being combined with the individual models for each pretreatment.
Four impact categories were analyzed, and a selection has been discussed based on relevance to the biofuel production process.
Results and discussion: In nearly all of the impact categories,
DA performs the worst due to the length of the process (12 h)
and the amount of electricity required to elevate the temperature to 60 °C for that time period. In many of the other categories, the remaining three pretreatments perform comparably to each other with the exception of LHW which has significantly reduced CO2 emissions. LHW has slightly higher water depletion rates than both SE and OS, which is to be expected given the nature of the process. In terms of product yield, LHW produced twice as much total sugar than any of the other processes.
Conclusions: The project concluded that while LHWand SE are viable options for the pretreatment of biomass, LHWis the most suitable technique for the pretreatment of corn stover. This pretreatment was environmentally friendly as it produced the lowest CO2 emissions, aligning with the main objective behind developing biofuels from agricultural residues. The process was also technically the most effective as it resulted in the highest sugar yields
Ball-free mechanochemistry: in situ real-time monitoring of pharmaceutical co-crystal formation by resonant acoustic mixing
Co-crystal formation by resonant acoustic mixing was followed for the first time by in situ real-time X-ray powder diffraction.</p
Structured evaluation of virtual environments for special-needs education
This paper describes the development of a structured approach to evaluate experiential and communication virtual learning environments (VLEs) designed specifically for use in the education of children with severe learning difficulties at the Shepherd special needs school in Nottingham, UK. Constructivist learning theory was used as a basis for the production of an evaluation framework, used to evaluate the design of three VLEs and how they were used by students with respect to this learning theory. From an observational field study of student-teacher pairs using the VLEs, 18 behaviour categories were identified as relevant to five of the seven constructivist principles defined by Jonassen (1994). Analysis of student-teacher behaviour was used to provide support for, or against, the constructivist principles. The results show that the three VLEs meet the constructivist principles in very different ways and recommendations for design modifications are put forward
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