8,627 research outputs found
Management of pediatric radiation dose using Philips fluoroscopy systems DoseWise: perfect image, perfect sense
Although image quality (IQ) is the ultimate goal for accurate diagnosis and treatment, minimizing radiation dose is equally important. This is especially true when pediatric patients are examined, because their sensitivity to radiation-induced cancer is two to three times greater than that of adults. DoseWise is an ALARA-based philosophy within Philips Medical Systems that is active at every level of product design. It encompasses a set of techniques, programs and practices that ensures optimal IQ while protecting people in the X-ray environments. DoseWise methods include management of the X-ray beam, less radiation-on time and more dose information for the operator. Smart beam management provides automatic customization of the X-ray beam spectrum, shape, and pulse frequency. The Philips-patented grid-controlled fluoroscopy (GCF) provides grid switching of the X-ray beam in the X-ray tube instead of the traditional generator switching method. In the examination of pediatric patients, DoseWise technology has been scientifically documented to reduce radiation dose to <10% of the dose of traditional continuous fluoroscopy systems. The result is improved IQ at a significantly lower effective dose, which contributes to the safety of patients and staff
It is not all about being sweet: differences in floral traits and insect visitation among hybrid carrot cultivars
Cytoplasmically male-sterile (CMS) carrot cultivars suffer from low pollination rates. In this study, insect visitation varied more than eightfold between 17 CMS carrot cultivars in a field-based cultivar evaluation trial. The visitation rates of honey bees, nectar scarabs, muscoid flies, and wasps each significantly differed among these cultivars. No significant difference in visitation rates was observed among cultivars of different CMS type (brown-anther or petaloid) or flower colour, but cultivars of Berlicumer root type had significantly higher insect visitation rates than Nantes. Six cultivars were further compared in regard to selected umbel traits: as umbel diameter increased, so did the visitation of soldier beetles, while that of honey bees decreased. Finally, nectar of these six cultivars was analysed for sugar content, which revealed monosaccharides to be the most common sugars in all. There was high variation in the levels of sugars from individual umbellets but no significant difference in nectar sugar composition among cultivars, suggesting that nectar sugar composition is of minor importance regarding pollinator attraction to hybrid CMS carrot umbels
Non-hermitian Exact Local Bosonic Algorithm for Dynamical Quarks
We present an exact version of the local bosonic algorithm for the simulation
of dynamical quarks in lattice QCD. This version is based on a non-hermitian
polynomial approximation of the inverse of the quark matrix. A Metropolis test
corrects the systematic errors. Two variants of this test are presented. For
both of them, a formal proof is given that this Monte Carlo algorithm converges
to the right distribution. Simulation data are presented for different lattice
parameters. The dynamics of the algorithm and its scaling in lattice volume and
quark mass are investigated.Comment: 32 pages, LaTex, 8 ps figure
Systematic study of autocorrelation time in pure SU(3) lattice gauge theory
Results of our autocorrelation measurement performed on Fujitsu AP1000 are
reported. We analyze (i) typical autocorrelation time, (ii) optimal mixing
ratio between overrelaxation and pseudo-heatbath and (iii) critical behavior of
autocorrelation time around cross-over region with high statistic in wide range
of for pure SU(3) lattice gauge theory on , and
lattices. For the mixing ratio K, small value (3-7) looks optimal in the
confined region, and reduces the integrated autocorrelation time by a factor
2-4 compared to the pseudo-heatbath. On the other hand in the deconfined phase,
correlation times are short, and overrelaxation does not seem to matter For a
fixed value of K(=9 in this paper), the dynamical exponent of overrelaxation is
consistent with 2 Autocorrelation measurement of the topological charge on
lattice at = 6.0 is also briefly mentioned.Comment: 3 pages of A4 format including 7-figure
Autocorrelation in Updating Pure SU(3) Lattice Gauge Theory by the use of Overrelaxed Algorithms
We measure the sweep-to-sweep autocorrelations of blocked loops below and
above the deconfinement transition for SU(3) on a lattice using
20000-140000 Monte-Carlo updating sweeps. A divergence of the autocorrelation
time toward the critical is seen at high blocking levels. The peak is
near = 6.33 where we observe 440 210 for the autocorrelation time
of Wilson loop on blocked lattice. The mixing of 7 Brown-Woch
overrelaxation steps followed by one pseudo-heat-bath step appears optimal to
reduce the autocorrelation time below the critical . Above the critical
, however, no clear difference between these two algorithms can be seen
and the system decorrelates rather fast.Comment: 4 pages of A4 format including 6-figure
Casimir effect for massless minimally coupled scalar field between parallel plates in de Sitter spacetime
Casimir effect for massless minimally coupled scalar field is studied. An
explicit answer for de Sitter spacetime is obtained and analized. Cosmological
implications of the result are discussed.Comment: 7 pages, 2 figure
Corporate Culture and Its Connection with External and Internal Public Relations
The main aim of this article is to present the influence of corporate culture on company's stakeholders. This paper signalises the tendency in corporate communication with its internal and external publics. It is focused on two issues: corporate social responsibility and employer branding. Those two categories are consequences of corporate culture model.Głównym celem artykułu jest zaprezentowanie wpływu jaki wywiera charakter kultury korporacyjnej na związanych z przedsiębiorstwem interesariuszy (stakeholders). W artykule zasygnalizowane zostały główne tendencje wyznaczające charakter komunikacji między organizacją a jej wewnętrznym i zewnętrznym otoczeniem. Tekst koncentruje się na dwóch kwestiach: społecznej odpowiedzialności przedsiębiorstwa (corporate social responsibilty) i budowanie wizerunku pracodawcy (employer branding), które zaprezentowane zostały jako efekty określonego modelu kultury organizacyjnej
The subconvexity problem for \GL_{2}
Generalizing and unifying prior results, we solve the subconvexity problem
for the -functions of \GL_{1} and \GL_{2} automorphic representations
over a fixed number field, uniformly in all aspects. A novel feature of the
present method is the softness of our arguments; this is largely due to a
consistent use of canonically normalized period relations, such as those
supplied by the work of Waldspurger and Ichino--Ikeda.Comment: Almost final version to appear in Publ. Math IHES. References
updated
Frequent insect visitors are not always pollen carriers in hybrid carrot pollination
Insect crop visitations do not necessarily translate to carriage or transfer of pollen. To evaluate the potential of the various insects visiting hybrid carrot flowers to facilitate pollen transfer, this study examines insect visitation rates to hybrid carrot seed crops in relation to weather, time of day and season, pollen carrying capacity, inter-row movement, and visitation frequency to male-fertile and male-sterile umbels. The highest pollen loads were carried by nectar scarabs, honey bees, and the hover fly Eristalis tenax (Linnaeus). Honey bees and muscoid flies were observed to forage mostly within the male fertile carrot row while nectar scarabs and E. tenax foraged across rows, carrying equal pollen loads regardless of their distance from the pollen source. All observed insect taxa were more frequently seen visiting male-fertile than male-sterile umbels. In contrast to other visiting insects, honey bees were abundant and frequent visitors and were observed carrying high pollen loads. Consequently, we suggest both optimizing honey bee management and improving the attraction of carrot lines to honey bees to improve pollination rates for hybrid carrot seed crops
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