36,651 research outputs found
Small quantity production of complex chromium alloy sheet /Cr-7Mo-2Ta-0.09C-0.1Y/ Final report
Fabrication of Cr-Mo-Ta-C-Y alloy shee
Daylight quantum key distribution over 1.6 km
Quantum key distribution (QKD) has been demonstrated over a point-to-point
-km atmospheric optical path in full daylight. This record
transmission distance brings QKD a step closer to surface-to-satellite and
other long-distance applications.Comment: 4 pages, 2 figures, 1 table. Submitted to PRL on 14 January 2000 for
publication consideratio
The twisted fourth moment of the Riemann zeta function
We compute the asymptotics of the fourth moment of the Riemann zeta function
times an arbitrary Dirichlet polynomial of length Comment: 28 pages. v2: added reference
Lagrangian versus Quantization
We discuss examples of systems which can be quantized consistently, although
they do not admit a Lagrangian description.Comment: 8 pages, no figures; small corrections, references adde
Experimental Verification of Surface Vehicle Dynamics
Experimental verification of surface vehicle dynamic
Large-scale and significant expression from pseudogenes in Sodalis glossinidius – a facultative bacterial endosymbiont
The majority of bacterial genomes have high coding efficiencies, but there are some genomes of intracellular bacteria that have low gene density. The genome of the endosymbiont Sodalis glossinidius contains almost 50 % pseudogenes containing mutations that putatively silence them at the genomic level. We have applied multiple ‘omic’ strategies, combining Illumina and Pacific Biosciences Single-Molecule Real-Time DNA sequencing and annotation, stranded RNA sequencing and proteome analysis to better understand the transcriptional and translational landscape of Sodalis pseudogenes, and potential mechanisms for their control. Between 53 and 74 % of the Sodalis transcriptome remains active in cell-free culture. The mean sense transcription from coding domain sequences (CDSs) is four times greater than that from pseudogenes. Comparative genomic analysis of six Illumina-sequenced Sodalis isolates from different host Glossina species shows pseudogenes make up ~40 % of the 2729 genes in the core genome, suggesting that they are stable and/or that Sodalis is a recent introduction across the genus Glossina as a facultative symbiont. These data shed further light on the importance of transcriptional and translational control in deciphering host–microbe interactions. The combination of genomics, transcriptomics and proteomics gives a multidimensional perspective for studying prokaryotic genomes with a view to elucidating evolutionary adaptation to novel environmental niches
The Properties of Some Caribbean Pine Pulps, and their Relationship to Wood Specific Gravity Variables
Twenty Caribbean pine trees were pulped individually, and the properties of these pulps were compared to each other and to those of pulps of five other softwood species. There was substantial tree to tree variation, but overall the properties compared favourably with those of pulps from the commercially better established species. X-ray densitometry of the wood was used to estimate the amount of wood in various specific gravity classes. By using such data it was possible to account for considerably more variation in pulp and paper properties than could be done by using overall specific gravity or percentage latewood. Histograms showing percentage in each specific gravity class differed markedly in shape for trees with the same overall specific gravity
Revealing New Physical Structures in the Supernova Remnant N63A through Chandra Imaging Spectroscopy
We present Chandra X-ray observations of the supernova remnant (SNR) N63A in
the Large Magellanic Cloud (LMC). N63A, one of the brightest LMC remnants, is
embedded in an H II region and probably associated with an OB association. The
optical remnant consists of three lobes of emission contained within the
approximately three times larger X-ray remnant. Our Chandra data reveal a
number of new physical structures in N63A. The most striking of these are the
several ``crescent''-shaped structures located beyond the main shell that
resemble similar features seen in the Vela SNR. In Vela, these have been
interpreted as arising from high speed clumps of supernova ejecta interacting
with the ambient medium. Another distinct feature of the remnant is a roughly
triangular ``hole'' in the X-ray emission near the location of the optical
lobes and the brightest radio emission. X-ray spectral analysis shows that this
deficit of emission is a result of absorption by an intervening dense cloud
with a mass of ~450 M_sun that is currently being engulfed by the remnant's
blast wave. We also find that the rim of the remnant, as well as the
crescent-shaped features, have considerably softer X-ray spectra than the
interior. Limits on hard X-ray emission rule out a young, energetic pulsar in
N63A, but the presence of an older or less active one, powering a wind nebula
with a luminosity less than ~4e10^34 erg/s, is allowed.Comment: 18 pages, 5 figures (2 color), accepted for publication in Ap
Correlations in the Far Infrared Background
We compute the expected angular power spectrum of the cosmic Far Infrared
Background (FIRB). We find that the signal due to source correlations dominates
the shot--noise for \ell \la 1000 and results in anisotropies with rms
amplitudes between 5% and 10% of the mean
for l \ga 150. The angular power spectrum depends on several unknown
quantities, such as the UV flux density evolution, optical properties of the
dust, biasing of the sources of the FIRB, and cosmological parameters. However,
when we require our models to reproduce the observed DC level of the FIRB, we
find that the anisotropy is at least a few percent in all cases. This
anisotropy is detectable with proposed instruments, and its measurement will
provide strong constraints on models of galaxy evolution and large-scale
structure at redshifts up to at least .Comment: 7 pages, 4 figures included, uses emulateapj.sty. More models
explored than in original version. Accepted for publication in Ap
Reducing smoking in adolescents: cost-effectiveness results from the cluster randomized ASSIST (A Stop Smoking In Schools Trial)
Introduction: School-based smoking prevention programmes can be effective, but evidence on cost-effectiveness is lacking. We conducted a cost-effectiveness analysis of a school-based “peer-led” intervention.<p></p>
Methods: We evaluated the ASSIST (A Stop Smoking In Schools Trial) programme in a cluster randomized controlled trial. The ASSIST programme trained students to act as peer supporters during informal interactions to encourage their peers not to smoke. Fifty-nine secondary schools in England and Wales were randomized to receive the ASSIST programme or usual smoking education. Ten thousand seven hundred and thirty students aged 12–13 years attended participating schools. Previous work has demonstrated that the ASSIST programme achieved a 2.1% (95% CI = 0%–4.2%) reduction in smoking prevalence. We evaluated the public sector cost, prevalence of weekly smoking, and cost per additional student not smoking at 24 months.<p></p>
Results: The ASSIST programme cost of £32 (95% CI = £29.70–£33.80) per student. The incremental cost per student not smoking at 2 years was £1,500 (95% CI = £669–£9,947). Students in intervention schools were less likely to believe that they would be a smoker at age 16 years (odds ratio [OR] = 0.80; 95% CI = 0.66–0.96).<p></p>
Conclusions: A peer-led intervention reduced smoking among adolescents at a modest cost. The intervention is cost-effective under realistic assumptions regarding the extent to which reductions in adolescent smoking lead to lower smoking prevalence and/or earlier smoking cessation in adulthood. The annual cost of extending the intervention to Year 8 students in all U.K. schools would be in the region of £38 million and could result in 20,400 fewer adolescent smokers.<p></p>
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