285 research outputs found
Marine Debris Survey Manual
Over the last several years, concern has increased about
the amount of man-made materials lost or discarded at
sea and the potential impacts to the environment. The
scope of the problem depends on the amounts and types
of debris. One problem in making a regional comparison
of debris is the lack of a standard methodology. The
objective of this manual is to discuss designs and methodologies for assessment studies of marine debris.
This manual has been written for managers, researchers,
and others who are just entering this area of study
and who seek guidance in designing marine debris surveys.
Active researchers will be able to use this manual
along with applicable references herein as a source for
design improvement. To this end, the authors have synthesized their work and reviewed survey techniques that
have been used in the past for assessing marine debris,
such as sighting surveys, beach surveys, and trawl surveys,
and have considered new methods (e.g., aerial photography).
All techniques have been put into a general survey
planning framework to assist in developing different marine
debris surveys. (PDF file contains 100 pages.
Synthesis of superhydrophobic polymer/tungsten (VI) oxide nanocomposite thin films
A method is presented to enable the preparation of superhydrophobic polymer/tungsten (VI) oxide (WO3) nanocomposite coatings on glass substrates. WO3 nanoparticles were incorporated via the swell-encapsulation-shrink method into superhydrophobic silicone polymer films deposited on glass via aerosol-assisted chemical vapour deposition (AACVD) to produce the novel nanocomposite films. The technique overcomes the limitations of previous methods for nanoparticle incorporation to provide a synthetic route to previously unattainable materials. The nanocomposite films retain the properties of the superhydrophobic polymer while the presence of the nanoparticles is clearly evident. As such, the films have a range of potential applications including high surface area photocatalysis and self-cleaning photochromic or electrochromic coatings. The two-stage synthesis is shown to be flexible and suggests great scope for producing any number of future novel materials. The thin films were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), infra-red (FTIR) spectroscopy, X-ray diffractometry (XRD) and water droplet contact angle measurements
Matrix models as conformal field theories: genus expansion
We obtain the topological expansion of the hermitian matrix model using its
representation as a CFT on a hyperelliptic Riemann surface. To each branch
point of the Riemann surface we associate an operator which represents a twist
field dressed by the modes of the twisted boson. The partition function of the
matrix model is computed as a correlation function of such dressed twist
fields. The perturbative construction of the dressing operators yields a set of
Feynman rules for evaluating the free energy and the loop observables at any
genus.Comment: 17 pages, 4 figure
Gene-based microsatellites for cassava (Manihot esculenta Crantz): prevalence, polymorphisms, and cross-taxa utility
Background: Cassava (Manihot esculenta Crantz), a starchy root crop grown in tropical and subtropical climates, is the sixth most important crop in the world after wheat, rice, maize, potato and barley. The repertoire of simple sequence repeat (SSR) markers for cassava is limited and warrants a need for a larger number of polymorphic SSRs for germplasm characterization and breeding applications.
Results: A total of 846 putative microsatellites were identified in silico from an 8,577 cassava unigene set with an average density of one SSR every 7 kb. One hundred and ninety-two candidate SSRs were screened for polymorphism among a panel of cassava cultivars from Africa, Latin America and Asia, four wild Manihot species as well as two other important taxa in the Euphorbiaceae, leafy spurge (Euphorbia esula) and castor bean (Ricinus communis). Of 168 markers with clean amplification products, 124 (73.8%) displayed polymorphism based on high resolution agarose gels. Of 85 EST-SSR markers screened, 80 (94.1%) amplified alleles from one or more wild species (M epruinosa, M glaziovii, M brachyandra, M tripartita) whereas 13 (15.3%) amplified alleles from castor bean and 9 (10.6%) amplified alleles from leafy spurge; hence nearly all markers were transferable to wild relatives of M esculenta while only a fraction was transferable to the more distantly related taxa. In a subset of 20 EST-SSRs assessed by fluorescence-based genotyping the number of alleles per locus ranged from 2 to 10 with an average of 4.55 per locus. These markers had a polymorphism information content (PIC) from 0.19 to 0.75 with an average value of 0.55 and showed genetic relationships consistent with existing information on these genotypes.
Conclusion: A set of 124 new, unique polymorphic EST-SSRs was developed and characterized which extends the repertoire of SSR markers for cultivated cassava and its wild relatives. The markers show high PIC values and therefore will be useful for cultivar identification, taxonomic studies, and genetic mapping. The study further shows that mining ESTs is a highly efficient strategy for polymorphism detection within the cultivated cassava gene pool
Navigating inferior vena cava filters in invasive cardiology procedures: A systematic review
BACKGROUND: Transfemoral venous access (TFV) is the cornerstone of minimally invasive cardiac procedures. Although the presence of inferior vena cava filters (IVCFs) was considered a relative contraindication to TFV procedures, small experiences have suggested safety. We conducted a systematic review of the available literature on cardiac procedural success of TFV with IVCF in-situ.
METHODS: Two independent reviewers searched PubMed, EMBASE, SCOPUS, and Google Scholar from inception to October 2020 for studies that reported outcomes in patients with IVCFs undergoing TFV for invasive cardiac procedures. We investigated a primary outcome of acute procedural success and reviewed the pooled data for patient demographics, procedural complications, types of IVCF, IVCF dwell time, and procedural specifics.
RESULTS: Of the 120 studies initially screened, 8 studies were used in the final analysis with a total of 100 patients who underwent 110 procedures. The most common IVCF was the Greenfield Filter (36%), 60% of patients were males and the mean age was 67.8 years. The overall pooled incidence of acute procedural success was 95.45% (95% confidence interval 89.54. - 98.1) with no heterogeneity (I2 = 0%, p = 1) and there were no reported filter related complications.
CONCLUSION: This systematic review is the largest study of its kind to demonstrate the safety and feasibility of TFV access in a variety of cardiac procedures in the presence of IVCF
Deep ACS Imaging in the Globular Cluster NGC 6397: The Cluster Color Magnitude Diagram and Luminosity Function
We present the CMD from deep HST imaging in the globular cluster NGC 6397.
The ACS was used for 126 orbits to image a single field in two colors (F814W,
F606W) 5 arcmin SE of the cluster center. The field observed overlaps that of
archival WFPC2 data from 1994 and 1997 which were used to proper motion (PM)
clean the data. Applying the PM corrections produces a remarkably clean CMD
which reveals a number of features never seen before in a globular cluster CMD.
In our field, the main sequence stars appeared to terminate close to the
location in the CMD of the hydrogen-burning limit predicted by two independent
sets of stellar evolution models. The faintest observed main sequence stars are
about a magnitude fainter than the least luminous metal-poor field halo stars
known, suggesting that the lowest luminosity halo stars still await discovery.
At the bright end the data extend beyond the main sequence turnoff to well up
the giant branch. A populous white dwarf cooling sequence is also seen in the
cluster CMD. The most dramatic features of the cooling sequence are its turn to
the blue at faint magnitudes as well as an apparent truncation near F814W = 28.
The cluster luminosity and mass functions were derived, stretching from the
turn off down to the hydrogen-burning limit. It was well modeled with either a
very flat power-law or a lognormal function. In order to interpret these fits
more fully we compared them with similar functions in the cluster core and with
a full N-body model of NGC 6397 finding satisfactory agreement between the
model predictions and the data. This exercise demonstrates the important role
and the effect that dynamics has played in altering the cluster IMF.Comment: 43 pages including 4 tables and 12 diagrams. Figures 2 and 3 have
been bitmapped. Accepted for publication in the Astronomical Journa
Precision Gauge Unification from Extra Yukawa Couplings
We investigate the impact of extra vector-like GUT multiplets on the
predicted value of the strong coupling. We find in particular that Yukawa
couplings between such extra multiplets and the MSSM Higgs doublets can resolve
the familiar two-loop discrepancy between the SUSY GUT prediction and the
measured value of alpha_3. Our analysis highlights the advantages of the
holomorphic scheme, where the perturbative running of gauge couplings is
saturated at one loop and further corrections are conveniently described in
terms of wavefunction renormalization factors. If the gauge couplings as well
as the extra Yukawas are of O(1) at the unification scale, the relevant
two-loop correction can be obtained analytically. However, the effect persists
also in the weakly-coupled domain, where possible non-perturbative corrections
at the GUT scale are under better control.Comment: 26 pages, LaTeX. v6: Important early reference adde
Improving programme-led and focused interventions for eating disorders: An experts' consensus statement-A UK perspective
OBJECTIVE: Eating disorders are associated with significant illness burden and costs, yet access to evidence-based care is limited. Greater use of programme-led and focused interventions that are less resource-intensive might be part of the solution to this demand-capacity mismatch. METHOD: In October 2022, a group of predominantly UK-based clinical and academic researchers, charity representatives and people with lived experience convened to consider ways to improve access to, and efficacy of, programme-led and focused interventions for eating disorders in an attempt to bridge the demand-capacity gap. RESULTS: Several key recommendations were made across areas of research, policy, and practice. Of particular importance is the view that programme-led and focused interventions are suitable for a range of different eating disorder presentations across all ages, providing medical and psychiatric risk are closely monitored. The terminology used for these interventions should be carefully considered, so as not to imply that the treatment is suboptimal. CONCLUSIONS: Programme-led and focused interventions are a viable option to close the demand-capacity gap for eating disorder treatment and are particularly needed for children and young people. Work is urgently needed across sectors to evaluate and implement such interventions as a clinical and research priority
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