1,340 research outputs found
Comparing bird and human soaring strategies
Gliding saves much energy, and to make large distances using only this form
of flight represents a great challenge for both birds and people. The solution
is to make use of the so-called thermals, which are localized, warmer regions
in the atmosphere moving upwards with a speed exceeding the descent rate of
bird and plane. Whereas birds use this technique mainly for foraging, humans do
it as a sporting activity. Thermalling involves efficient optimization
including the skilful localization of thermals, trying to guess the most
favorable route, estimating the best descending rate, etc. In this study, we
address the question whether there are any analogies between the solutions
birds and humans find to handle the above task. High-resolution track logs were
taken from thermalling falcons and paraglider pilots to determine the essential
parameters of the flight patterns. We find that there are relevant common
features in the ways birds and humans use thermals. In particular, falcons seem
to reproduce the MacCready formula widely used by gliders to calculate the best
slope to take before an upcoming thermal.Comment: 8 pages, 4 figures. Supplementary materials are available at the
webpage dedicated to this work: http://angel.elte.hu/thermalling
Extraction of information about periodic orbits from scattering functions
As a contribution to the inverse scattering problem for classical chaotic
systems, we show that one can select sequences of intervals of continuity, each
of which yields the information about period, eigenvalue and symmetry of one
unstable periodic orbit.Comment: LaTeX, 13 pages (includes 5 eps-figures
Examination of Affective Responses to Images in Sponsorship-Linked Marketing
Sponsorship of sports, arts, charity and entertainment events are all viewed as capable in building corporate and brand image. In this process, visual images are a key vehicle in the transportation of affect from an event to a brand. While the overall positive feeling of a sponsored event or activity is argued to rub-off on a brand, we know less about how individual images function in this process and we know even less about the role of negative images. Here, three experiments consider the potential of affect transfer from images to brands. All three experiments show explicit transfer of affect, and one finds implicit evaluative change. Importantly, positive images when mixed with negative are off-setting. This research suggests that when negative events occur and are captured and repeated in the media, practitioners able to supply positive images may be able to control negative affective responses to some degree
Comment on ``Reduction of static field equation of Faddeev model to first order PDE'', arXiv:0707.2207
The authors of the article Phys. Lett. B 652 (2007) 384, (arXiv:0707.2207),
propose an interesting method to solve the Faddeev model by reducing it to a
set of first order PDEs. They first construct a vectorial quantity , depending on the original field and its first derivatives, in terms of which
the field equations reduce to a linear first order equation. Then they find
vectors and which identically obey this linear
first order equation. The last step consists in the identification of the with the original as a function of the original field.
Unfortunately, the derivation of this last step in the paper cited above
contains an error which invalidates most of its results
Turnover of microbial lipids in the deep biosphere and growth of benthic archaeal populations
Deep subseafloor sediments host a microbial biosphere with unknown impact on global biogeochemical cycles. This study tests previous evidence based on microbial intact polar lipids (IPLs) as proxies of live biomass, suggesting that Archaea dominate the marine sedimentary biosphere: We devised a sensitive radiotracer assay to measure the decay rate of ([C-14]glucosyl)-diphytanylglyceroldiether (GlcDGD) as an analog of archaeal IPLs in continental margin sediments. The degradation kinetics were incorporated in model simulations that constrained the fossil fraction of subseafloor IPLs and rates of archaeal turnover. Simulating the top 1 km in a generic continental margin sediment column, we estimated degradation rate constants of GlcDGD being one to two orders of magnitude lower than those of bacterial IPLs, with half-lives of GlcDGD increasing with depth to 310 ky. Given estimated microbial community turnover times of 1.6-73 ky in sediments deeper than 1 m, 50-96% of archaeal IPLs represent fossil signals. Consequently, previous lipid-based estimates of global subseafloor biomass probably are too high, and the widely observed dominance of archaeal IPLs does not rule out a deep biosphere dominated by Bacteria. Reverse modeling of existing concentration profiles suggest that archaeal IPL synthesis rates decline from around 1,000 pg.mL(-1) sediment.y(-1) at the surface to 0.2 pg.mL(-1).y(-1) at 1 km depth, equivalent to production of 7 x 10(5) to 140 archaeal cells.mL(-1) sediment.y(-1), respectively. These constraints on microbial growth are an important step toward understanding the relationship between the deep biosphere and the carbon cycle
Detection of triplex PCR for the modified qualitative soybean and maize genetically
A molecular screening method based on multiplex PCR that involves amplification of specific soybean or maize sequences from plant DNA (lectin or zein) and the amplification of 35S promoter and NOS terminator,for the detection of genetically modified soybean and maize was developed. The new method is proposed,for the simulicmeous cletcctimt of tree genetic elements in the.same run as reliable method for rapid detection of genetically, modified plants with sensitivity of 0.1%
Hereditary hydrocephalus internus in a laboratory strain of golden hamsters (Mesocricetus auratus)
Golden hamsters of one common laboratory strain had a high incidence of hydrocephalus internus. When a severity score of hydrocephalus was used, a major autosomal recessive locus could be identified. However, when a binary score (hydrocephalus, no hydrocephalus) was used, no such major locus could be detected and results of test matings were not consistent with Mendelian inheritance. Golden hamsters with severe forms of hydrocephalus had a dorsally compressed and ventrally intact hippocampus. Implications for the behavior and well-being of affected hamsters are unknown but researchers using this strain should be aware of the likely presence of hydrocephalu
Development of planar pixel modules for the ATLAS high luminosity LHC tracker upgrade
The high-luminosity LHC will present significant challenges for tracking systems. ATLAS is preparing to upgrade the entire tracking system, which will include a significantly larger pixel detector. This paper reports on the development of large area planar detectors for the outer pixel layers and the pixel endcaps. Large area sensors have been fabricated and mounted onto 4 FE-I4 readout ASICs, the so-called quad-modules, and their performance evaluated in the laboratory and testbeam. Results from characterisation of sensors prior to assembly, experience with module assembly, including bump-bonding and results from laboratory and testbeam studies are presented
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