1,155 research outputs found
Structural design of elliptical hollow sections: a review
Tubular construction is synonymous with modern architecture. The familiar range of tubular sections – square, rectangular and circular hollow sections – has been recently extended to include elliptical hollow sections (EHSs). Due to differing flexural rigidities about the two principal axes, these new sections combine the elegance of circular hollow sections with the improved structural efficiency in bending of rectangular hollow sections. Following the introduction of structural steel EHSs, a number of investigations into their structural response have been carried out. This paper presents a state-of-the-art review of recent research on EHSs together with a sample of practical applications. The paper addresses fundamental research on elastic local buckling and post-buckling, cross-section classification, response in shear, member instabilities, connections and the behaviour of concrete-filled EHSs. Details of full-scale testing and numerical modelling studies are described, and the generation of statistically validated structural design rules, suitable for incorporation into international design codes, is outlined
Meeple Centred Design: A Heuristic Toolkit for Evaluating the Accessibility of Tabletop Games
Evaluation of accessibility within a tabletop context is much more complicated than it is within a video game environment. There is a considerable amount of variation in game systems, game mechanisms, and interaction regimes. Games may be entirely verbal, or completely non-verbal. They might be real-time or turn based, or based on simultaneous actions. They can be competitive or co-operative, or shift from one to the other during a single game session. They might involve visual pattern recognition or force players to memorise game state without visual cues. They may involve touch, or smell. They might involve social deduction or betrayal. They can encompass all sensory faculties, in differing degrees. Almost all games have accessibility considerations that should be taken into account, but there is currently no comprehensive tool by which this can be done that encompasses the rich variety of tabletop gaming interaction metaphors. In this paper, the authors discuss the heuristic lens that is used by the Meeple Centred Design tabletop accessibility project. This is a tool that has been applied to one hundred and sixteen games to date, and the full results of these have been published for analysis and consideration within the wider tabletop gaming community
Very special relativity as relativity of dark matter: the Elko connection
In the very special relativity (VSR) proposal by Cohen and Glashow, it was
pointed out that invariance under HOM(2) is both necessary and sufficient to
explain the null result of the Michelson-Morely experiment. It is the quantum
field theoretic demand of locality, or the requirement of P, T, CP, or CT
invariance, that makes invariance under the Lorentz group a necessity.
Originally it was conjectured that VSR operates at the Planck scale; we propose
that the natural arena for VSR is at energies similar to the standard model,
but in the dark sector. To this end we provide an ab initio spinor
representation invariant under the SIM(2) avatar of VSR and construct a mass
dimension one fermionic quantum field of spin one half. This field turns out to
be a very close sibling of Elko and it exhibits the same striking property of
intrinsic darkness with respect to the standard model fields. In the new
construct, the tension between Elko and Lorentz symmetries is fully resolved.
We thus entertain the possibility that the symmetries underlying the standard
model matter and gauge fields are those of Lorentz, while the event space
underlying the dark matter and the dark gauge fields supports the algebraic
structure underlying VSR.Comment: 19 pages. Section 5 is new. Published version (modulo a footnote, and
a corrected typo
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SDSS IV MaNGA-spatially resolved diagnostic diagrams: A proof that many galaxies are LIERs
We study the spatially resolved excitation properties of the ionised gas in a
sample of 646 galaxies using integral field spectroscopy data from SDSS-IV
MaNGA. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we
demonstrate the ubiquitous presence of extended (kpc scale) low ionisation
emission-line regions (LIERs) in both star forming and quiescent galaxies. In
star forming galaxies LIER emission can be associated with diffuse ionised gas,
most evident as extra-planar emission in edge-on systems. In addition, we
identify two main classes of galaxies displaying LIER emission: `central LIER'
(cLIER) galaxies, where central LIER emission is spatially extended, but
accompanied by star formation at larger galactocentric distances, and `extended
LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole
galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially
flat, low H equivalent width of line emission ( 3 \AA) and stellar
population indices demonstrating the lack of young stellar populations,
implying that line emission follows tightly the continuum due to the underlying
old stellar population. The H surface brightness radial profiles are
always shallower than and the line ratio
[OIII]5007/[OII]3727,29 (a tracer of the ionisation parameter
of the gas) shows a flat gradient. This combined evidence strongly supports the
scenario in which LIER emission is not due to a central point source but to
diffuse stellar sources, the most likely candidates being hot, evolved
(post-asymptotic giant branch) stars. Shocks are observed to play a significant
role in the ionisation of the gas only in rare merging and interacting systems.STFCThis is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Oxford University Press
PCB pollution continues to impact populations of orcas and other dolphins in European waters
Organochlorine (OC) pesticides and the more persistent polychlorinated biphenyls (PCBs) have well-established dose-dependent toxicities to birds, fish and mammals in experimental studies, but the actual impact of OC pollutants on European marine top predators remains unknown. Here we show that several cetacean species have very high mean blubber PCB concentrations likely to cause population declines and suppress population recovery. In a large pan-European meta-analysis of stranded (n = 929) or biopsied (n = 152) cetaceans, three out of four species:- striped dolphins (SDs), bottlenose dolphins (BNDs) and killer whales (KWs) had mean PCB levels that markedly exceeded all known marine mammal PCB toxicity thresholds. Some locations (e.g. western Mediterranean Sea, south-west Iberian Peninsula) are global PCB "hotspots" for marine mammals. Blubber PCB concentrations initially declined following a mid-1980s EU ban, but have since stabilised in UK harbour porpoises and SDs in the western Mediterranean Sea. Some small or declining populations of BNDs and KWs in the NE Atlantic were associated with low recruitment, consistent with PCB-induced reproductive toxicity. Despite regulations and mitigation measures to reduce PCB pollution, their biomagnification in marine food webs continues to cause severe impacts among cetacean top predators in European seas
Primary retroperitoneal mucinous cystadenocarcinoma: report of two cases
BACKGROUND: Retroperitoneal cystadenocarcinomas are rare lesions, the majority of cases presented as one-patient reports. METHODS: We present two cases of retroperitoneal cystadenocarcinoma, both in women of reproductive age: one with aggressive behavior, and the remaining case, with a more indolent clinical evolution. RESULTS: One case presented as pelvic tumor, was treated with surgical resection of the disease, but manifested with recurrent disease a few months later despite use of chemotherapy. The second case involved a patient with diagnosis of abdominal tumor; during laparotomy, a retroperitoneal tumor was found and was totally removed. At follow-up, the patient is disease-free with no other treatment. CONCLUSION: The behavior and treatment of retroperitoneal cystadenocarcinoma are controversial. We suggest aggressive surgery including radical hysterectomy and bilateral salpingoopherectomy with adjuvant chemotherapy in these cases
Uterine tumours are a phenotypic manifestation of the hyperparathyroidism-jaw tumour syndrome
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74672/1/j.1365-2796.2004.01421.x.pd
From DNA sequence to application: possibilities and complications
The development of sophisticated genetic tools during the past 15 years have facilitated a tremendous increase of fundamental and application-oriented knowledge of lactic acid bacteria (LAB) and their bacteriophages. This knowledge relates both to the assignments of open reading frames (ORF’s) and the function of non-coding DNA sequences. Comparison of the complete nucleotide sequences of several LAB bacteriophages has revealed that their chromosomes have a fixed, modular structure, each module having a set of genes involved in a specific phase of the bacteriophage life cycle. LAB bacteriophage genes and DNA sequences have been used for the construction of temperature-inducible gene expression systems, gene-integration systems, and bacteriophage defence systems.
The function of several LAB open reading frames and transcriptional units have been identified and characterized in detail. Many of these could find practical applications, such as induced lysis of LAB to enhance cheese ripening and re-routing of carbon fluxes for the production of a specific amino acid enantiomer. More knowledge has also become available concerning the function and structure of non-coding DNA positioned at or in the vicinity of promoters. In several cases the mRNA produced from this DNA contains a transcriptional terminator-antiterminator pair, in which the antiterminator can be stabilized either by uncharged tRNA or by interaction with a regulatory protein, thus preventing formation of the terminator so that mRNA elongation can proceed. Evidence has accumulated showing that also in LAB carbon catabolite repression in LAB is mediated by specific DNA elements in the vicinity of promoters governing the transcription of catabolic operons.
Although some biological barriers have yet to be solved, the vast body of scientific information presently available allows the construction of tailor-made genetically modified LAB. Today, it appears that societal constraints rather than biological hurdles impede the use of genetically modified LAB.
A Novel Method to Adjust Efficacy Estimates for Uptake of Other Active Treatments in Long-Term Clinical Trials
BACKGROUND: When rates of uptake of other drugs differ between treatment arms in long-term trials, the true benefit or harm of the treatment may be underestimated. Methods to allow for such contamination have often been limited by failing to preserve the randomization comparisons. In the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study, patients were randomized to fenofibrate or placebo, but during the trial many started additional drugs, particularly statins, more so in the placebo group. The effects of fenofibrate estimated by intention-to-treat were likely to have been attenuated. We aimed to quantify this effect and to develop a method for use in other long-term trials. METHODOLOGY/PRINCIPAL FINDINGS: We applied efficacies of statins and other cardiovascular drugs from meta-analyses of randomized trials to adjust the effect of fenofibrate in a penalized Cox model. We assumed that future cardiovascular disease events were reduced by an average of 24% by statins, and 20% by a first other major cardiovascular drug. We applied these estimates to each patient who took these drugs for the period they were on them. We also adjusted the analysis by the rate of discontinuing fenofibrate. Among 4,900 placebo patients, average statin use was 16% over five years. Among 4,895 assigned fenofibrate, statin use was 8% and nonuse of fenofibrate was 10%. In placebo patients, use of cardiovascular drugs was 1% to 3% higher. Before adjustment, fenofibrate was associated with an 11% reduction in coronary events (coronary heart disease death or myocardial infarction) (P = 0.16) and an 11% reduction in cardiovascular disease events (P = 0.04). After adjustment, the effects of fenofibrate on coronary events and cardiovascular disease events were 16% (P = 0.06) and 15% (P = 0.008), respectively. CONCLUSIONS/SIGNIFICANCE: This novel application of a penalized Cox model for adjustment of a trial estimate of treatment efficacy incorporates evidence-based estimates for other therapies, preserves comparisons between the randomized groups, and is applicable to other long-term trials. In the FIELD study example, the effects of fenofibrate on the risks of coronary heart disease and cardiovascular disease events were underestimated by up to one-third in the original analysis. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN64783481
Combined Analysis of all Three Phases of Solar Neutrino Data from the Sudbury Neutrino Observatory
We report results from a combined analysis of solar neutrino data from all
phases of the Sudbury Neutrino Observatory. By exploiting particle
identification information obtained from the proportional counters installed
during the third phase, this analysis improved background rejection in that
phase of the experiment. The combined analysis resulted in a total flux of
active neutrino flavors from 8B decays in the Sun of (5.25 \pm
0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino
oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5}
eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino
oscillation analysis combining this result with results of all other solar
neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} =
(7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} =
0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} =
(2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of
sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.)
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