1,726 research outputs found
A review of landscape rehabilitation frameworks in ecosystem engineering for mine closure
Mining causes changes to the environment and rehabilitation is necessary at mine closure. There is a lack of appropriate frameworks for mine site rehabilitation. In most cases, restoring the mine to previous conditions
is challenging. Alternatively, mining companies can engineer ecosystems to suit new site conditions and aim for a self-sustaining and resilient ecosystem. In ecosystem design there should be consideration of the four key dimensions of any ecosystem; landscape, function, structure and composition (LFSC). Alcoaâs Bauxite mines and Barrick (Cowal) Limitedâs Gold Mine have considered LFSC in their rehabilitation practices. From this, a framework based on LFSC is proposed as a means of planning, undertaking and monitoring
mine rehabilitation, which together aim for a self-sustaining and resilient ecosystem. Elements of this framework are being utilised in the industry, and are supported by research. The framework could be used
as an industry standard, utilised by regulatory bodies and potentially used in conjunction with other models and in other rehabilitation environments
Transposable elements: Powerful contributors to angiosperm evolution and diversity
Transposable elements (TEs) are a dominant feature of most flowering plant genomes. Together with other accepted facilitators of evolution, accumulating data indicate that TEs can explain much about their rapid evolution and diversification. Genome size in angiosperms is highly correlated with TE content and the overwhelming bulk (>80%) of large genomes can be composed of TEs. Among retro-TEs, long terminal repeats (LTRs) are abundant, whereas DNA-TEs, which are often less abundant than retro-TEs, are more active. Much adaptive or evolutionary potential in angiosperms is due to the activity of TEs (active TE-Thrust), resulting in an extraordinary array of genetic changes, including gene modifications, duplications, altered expression patterns, and exaptation to create novel genes, with occasional gene disruption. TEs implicated in the earliest origins of the angiosperms include the exapted Mustang, Sleeper, and Fhy3/Far1 gene families. Passive TE-Thrust can create a high degree of adaptive or evolutionary potential by engendering ectopic recombination events resulting in deletions, duplications, and karyotypic changes. TE activity can also alter epigenetic patterning, including that governing endosperm development, thus promoting reproductive isolation. Continuing evolution of long-lived resprouter angiosperms, together with genetic variation in their multiple meristems, indicates that TEs can facilitate somatic evolution in addition to germ line evolution. Critical to their success, angiosperms have a high frequency of polyploidy and hybridization, with resultant increased TE activity and introgression, and beneficial gene duplication. Together with traditional explanations, the enhanced genomic plasticity facilitated by TE-Thrust, suggests a more complete and satisfactory explanation for Darwinâs âabominable mysteryâ: the spectacular success of the angiosperms
Localized Tachyons and the g_cl conjecture
We consider C/Z_N and C^2/Z_N orbifolds of heterotic string theories and Z_N
orbifolds of AdS_3. We study theories with N=2 worldsheet superconformal
invariance and construct RG flows. Following Harvey, Kutasov, Martinec and
Moore, we compute g_cl and show that it decreases monotonically along RG flows-
as conjectured by them. For the heterotic string theories, the gauge degrees of
freedom do not contribute to the computation of g_cl.Comment: Corrections and clarifications made, 19 page
Recommended from our members
Implementing the UN Action Programme for Combating the Illicit Trafficking in Small Arms and Light Weapons in All Its Aspects.
yesHistorically, UN conferences have been criticised for resulting more in compromises than in
commitments to real change, which is also a charge that has been levelled against the UN
Conference on the Illicit Trade in Small Arms and Light Weapons in All Its Aspects (UN Small
Arms Conference). The consensus-based approach adopted throughout the negotiations had
the advantage of binding all participating States to all aspects of the agreed Programme of
Action (PoA), but it also ensured that it would be difficult to achieve a sufficiently rigorous and
comprehensive agreement on all of the measures required to tackle the trafficking,
proliferation and misuse of small arms and light weapons (SALW). Therefore, in spite of the
efforts of many governments and NGOs, the UN Small Arms Conference did not agree
sufficiently robust agreements in several areas. Nonetheless, it was a valuable and productive
process. The resulting PoA includes a reasonably comprehensive set of key principles and
commitments, which provide a basis for taking forward action at national, regional and global
levels. The PoAwas agreed by all of the participating States, amounting to more than 100,
and each are politically bound to adopt and implement it.
Given that the UN Small Arms Conference was the first of its kind, its achievement in
generating political will and momentum for efforts to control SALW is important. Although
many of the commitments are weaker and less comprehensive than hoped for by many
governments and organisations, it is significant that the PoAcontains at least some important
commitments in all but two of the `coreÂż issue areas raised by States. The two exceptions
relate to transfers to non-State actors and to civilian trade, possession and use of SALW,
restrictions which were strongly opposed by the USA. Equally, human rights related issues
were noteworthy by their absence in the PoA.
Whilst the process of reaching agreement began with a far-reaching draft PoA in December
2000 (A/Conf.192/L.4), most of the comments that were tabled on this text during the second
Preparatory Committee in January 2001 came from countries that sought to weaken its
commitments. The subsequent draft (A/Conf.192/L.4/Rev.1) was therefore weaker, with the
result that progressive States faced an uphill task in seeking to strengthen its provisions.
The next draft PoA emerged at the UN Small Arms Conference itself in the form of a third draft
(A/Conf.192/L.5). Although still limited in a number of key areas Âż such as export criteria and
transparency Âż this document went further than L.4/Rev.1 in a number of respects and included
specific international commitments, including on brokering and tracing lines of supply. This,
however, proved too ambitious an agenda for a small group of States and in the end the document
that was adopted by consensus (A/Conf.192/L.5/Rev.1) represented a lower-level compromise.
Despite the difficulties of agreeing the consensus-based PoA, the process culminating in the
agreement was perhaps as important as the agreement itself. UN Small Arms Conference
represented the first time that all UN Member States had met to discuss the illicit trade in SALW
in all its aspects with a view to agreeing a comprehensive set of measures to address the
problem. Although many of the commitments contained in the PoAare couched in equivocal
language that will allow States to do as much or as little as they like, it is clear that the UN Small
Arms Conference has contributed to a much better understanding, amongst all stakeholders, of
the nature of the illicit trade in SALW and of the particular concerns and priorities of different
countries and sub-regions. It is also clear that although the Programme of Action provides a set
of minimum standards and commitments which all states should adopt, it also encourages
further action from all States willing to adopt more stringent commitments and stronger
programmes. There is a willingness among a number of States to build upon the PoAand take
more concrete and far-reaching measures at national, sub-regional, regional and international
levels, such as specific arrangements for tracing co-operation, or mechanisms to co-ordinate
e fforts to improve stockpile security or weapons destruction. This briefing provides a critical assessment of key provisions in the UN Small Arms
Conference PoA. Section 1 measures the overall outcomes of the conference against those
that the Biting the Bullet (BtB) project proposed as optimal conclusions, and suggests ways to
put the commitments contained in the PoA into practice. Section 2 assesses the
implementation and follow-up commitments contained in the PoA, and identifies ways of
promoting the implementation of Sections III and IV, as well as options for making the most of
the Biennial Meetings of States and the Review Conference in 2006. Section 3 examines
funding and resourcing possibilities for the PoA including identifying needs, mobilising
resources and matching needs with resources. The final section of the briefing focuses on the
way forward, and in particular on how implementation of the PoA could build on existing
regional initiatives and develop common international approaches to controlling SALW
proliferation, availability and misuse. It also examines how action to prevent and combat the
illicit trade in SALW in all its aspects can be taken forward at sub-regional and regional levels
in conjunction with all major stakeholders, including civil society, in the period leading up to
the first Review Conference
Domestic Rivalry and Export Performance: Theory and Evidence from International Airline Markets
The much-studied relationship between domestic rivalry and export performance consists of those supporting a national-champion rationale, and those supporting a rivalry rationale. While the empirical literature generally supports the positive effects of domestic rivalry, the national-champion rationale actually rests on firmer theoretical ground. We address this inconsistency by providing a theoretical framework that illustrates three paths via which domestic rivalry translates into enhanced international exports. Furthermore, empirical tests on the world airline industry elicit the existence of one particular path - an enhanced firm performance effect - that connects domestic rivalry with improved international exports
Physics Implications of Flat Directions in Free Fermionic Superstring Models II: Renormalization Group Analysis
We continue the investigation of the physics implications of a class of flat
directions for a prototype quasi-realistic free fermionic string model (CHL5),
building upon the results of the previous paper in which the complete mass
spectrum and effective trilinear couplings of the observable sector were
calculated to all orders in the superpotential. We introduce soft supersymmetry
breaking mass parameters into the model, and investigate the gauge symmetry
breaking patterns and the renormalization group analysis for two representative
flat directions, which leave an additional as well as the SM gauge
group unbroken at the string scale. We study symmetry breaking patterns that
lead to a phenomenologically acceptable hierarchy, and for electroweak and intermediate
scale symmetry breaking, respectively, and the associated mass
spectra after electroweak symmetry breaking. The fermion mass spectrum exhibits
unrealistic features, including massless exotic fermions, but has an
interesting -quark hierarchy and associated CKM matrix in one case. There
are (some) non-canonical effective terms, which lead to a non-minimal
Higgs sector with more than two Higgs doublets involved in the symmetry
breaking, and a rich structure of Higgs particles, charginos, and neutralinos,
some of which, however, are massless or ultralight. In the electroweak scale
cases the scale of supersymmetry breaking is set by the mass, with the
sparticle masses in the several TeV range.Comment: 38 pages, 5 figures, LaTex. Minor correction
C^2/Z_n Fractional branes and Monodromy
We construct geometric representatives for the C^2/Z_n fractional branes in
terms of branes wrapping certain exceptional cycles of the resolution. In the
process we use large radius and conifold-type monodromies, and also check some
of the orbifold quantum symmetries. We find the explicit Seiberg-duality which
connects our fractional branes to the ones given by the McKay correspondence.
We also comment on the Harvey-Moore BPS algebras.Comment: 34 pages, v1 identical to v2, v3: typos fixed, discussion of
Harvey-Moore BPS algebras update
Infection prevention practices in the Netherlands: results from a National Survey
Objective: To examine the extent to which acute care hospitals in the Netherlands have adopted recommended practices to prevent catheter-associated urinary tract infection (CAUTI), central line-associated bloodstream infection (CLABSI), ventilator-associated pneumonia (VAP), and Clostridioides difficile infection (CDI). Methods: Between 18 July 2017 and 31 October 2017, we surveyed the infection prevention teams of all acute care hospitals in the Netherlands. The survey instrument was based on the 'Translating Healthcare-Associated Infection Prevention Research into Practice' (TRIP) questionnaire and adapted to the Dutch context. Descriptive statistics were used to examine the reported regular use of CAUTI, CLABSI, VAP, and CDI prevention practices as well as the hospital characteristics. Results: Out of 72 eligible hospitals, 47 (65.3%) responded. Surveillance systems for monitoring CAUTI, CLABSI, VAP, and CDI were present in 17.8, 95.4, 26.2, and 77.3% of hospitals, respectively. Antimicrobial stewardship programs have been established in 91.5% of participating hospitals. For CAUTI, the majority of hospitals regularly used aseptic technique during catheter insertion (95%) and portable bladder ultrasound scanners (86.1%). Intermittent catheterization and catheter stop-orders were regularly used by 65.8 and 62.2% of hospitals. For CLABSI, all hospitals regularly used maximum sterile barrier precautions and chlorhexidine gluconate for insertion site antisepsis. Avoidance of the femoral site for central line insertions was regularly used by 65.9% of hospitals. Urinary catheters and central-lines impregnated with antibiotics or antiseptics were rarely used (†5%). Selective decontamination strategies for preventing VAP were used in 84% of hospitals. With the exception of disposable thermometers (31.8%), all prevention practices to prevent CDI were regularly used by more
Fractal Properties of Robust Strange Nonchaotic Attractors in Maps of Two or More Dimensions
We consider the existence of robust strange nonchaotic attractors (SNA's) in
a simple class of quasiperiodically forced systems. Rigorous results are
presented demonstrating that the resulting attractors are strange in the sense
that their box-counting dimension is N+1 while their information dimension is
N. We also show how these properties are manifested in numerical experiments.Comment: 9 pages, 14 figure
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