3,162 research outputs found
Catalytic RNA and synthesis of the peptide bond
We are studying whether the L-19 IVS ribozyme from Tetrahymena thermophila can catalyze the formation of the peptide bond when it is supplied with synthetic aminoacyl oligonucleotides. If this reaction works, it could give us some insight into the mechanism of peptide bond formation and the origin of coded protein synthesis. Two short oligoribonucleotides, CCCCC and a protected form of CCCCU were prepared; the former was made by the controlled hydrolysis of Poly(C), and the later by multistep chemical synthesis from the protected monomers. The homopentamer was then aminocylated using C-14 labelled Boc-protected glycine imidazolide. This aminoacylated oligo-nucleotide has now been shown to enter the active site of the L-19 IVS, and aminoacyl transfer, and peptide bond formation reactions are being sought. Our synthesis of CCCCU made us aware of the inadequacy of many of the 2'- hydroxyl protecting groups that are in use today and we therefore designed a new 2'- protecting group that is presently being tested
Form factor approach to dynamical correlation functions in critical models
We develop a form factor approach to the study of dynamical correlation
functions of quantum integrable models in the critical regime. As an example,
we consider the quantum non-linear Schr\"odinger model. We derive
long-distance/long-time asymptotic behavior of various two-point functions of
this model. We also compute edge exponents and amplitudes characterizing the
power-law behavior of dynamical response functions on the particle/hole
excitation thresholds. These last results confirm predictions based on the
non-linear Luttinger liquid method. Our results rely on a first principles
derivation, based on the microscopic analysis of the model, without invoking,
at any stage, some correspondence with a continuous field theory. Furthermore,
our approach only makes use of certain general properties of the model, so that
it should be applicable, with possibly minor modifications, to a wide class of
(not necessarily integrable) gapless one dimensional Hamiltonians.Comment: 33 page
Dysplazja kregosłupowo-przynasadowa : Kozlowski
Background: Kozlowski type spondylo-metaphyseal dysplasia is the most frequent form among spondylometaphyseal dysplasias. Case report: The first cases of such dysplasia among Gypsies - a father and two sons - have been described. Conclusions: Radiographic examination is the only means by which to diagnose Kozlowski type spondylometaphyseal dysplasia with certainty. Correct diagnosis is not only prognostic for the course of the disease and its complications, but also excludes the necessity of further, often expensive, investigations
Mini Max Wallpaper
Mini Max company formulated a problem for the automatic calculation of the number of wallpaper rolls necessary for decorating a room with wallpaper. The final goal is the development of a web-based calculator open for use to both Mini Max staff and the general public. We propose an approach for reducing the studied problem to the one-dimensional cutting-stock problem. We show this in details for the case of plain wallpapers as well as for the case of patterned wallpapers with straight match. The one-dimensional cutting-stock problem can be formulated as a linear integer programming problem. We develop an approach for calculating the needed number of wallpapers for relatively small problems, create an algorithm in a suitable graphical interface and make different tests. The tests show the efficiency of the proposed approach compared with the existent (available) wallpapers’ calculators
Change in the surface density of immobilized enzyme molecules due to photoelectron processes in a silicon substrate
The work was supported by the Russian Foundation for Basic Research, projects no. 16-08-00524
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Ignoring Puff Counts: Another Shortcoming of the Federal Trade Commission Cigarette Testing Programme
OBJECTIVES; To examine reasons behind the failure of the Federal Trade Commission (FTC) to preserve puff count information from standard cigarette testing and to elucidate the importance of puff count to overall tar yields.METHODS; We reviewed industry documents on origins of the FTC test and data sets provided by the Tobacco Institute Testing Laboratory to the tobacco industry and FTC for reporting purposes.RESULTS; The majority of the tobacco industry argued for "dual reporting" of tar yields-both per cigarette and per puff. Despite a request from the Tobacco Institute in 1967 that puff count information be preserved, documents and recent communications with the FTC indicate that puff number data have not been maintained by the government. In contrast, for the cigarette industry, puff count data are a fundamental and routine part of testing and important to cigarette design. A sample of puff counts for cigarettes tested in 1996 (n = 471) shows that on average 100 mm cigarettes have 18% more puffs taken on them than do 85 mm cigarettes in standard tests (7.66 vs 9.03; p<0.01). The 10th percentile puff count is 6.8 and the 90th percentile is 8.8 for king size; the 10th percentile puff count is 8.2 and the 90th percentile is 10.0 for 100 mm cigarettes, indicating that puff counts can vary substantially among brands.CONCLUSIONS; The FTC has failed to seek or preserve puff count information that the industry finds important. Any standard test of tar and nicotine yields should at minimum preserve puff count information
Theory of agent-based market models with controlled levels of greed and anxiety
We use generating functional analysis to study minority-game type market
models with generalized strategy valuation updates that control the psychology
of agents' actions. The agents' choice between trend following and contrarian
trading, and their vigor in each, depends on the overall state of the market.
Even in `fake history' models, the theory now involves an effective overall bid
process (coupled to the effective agent process) which can exhibit profound
remanence effects and new phase transitions. For some models the bid process
can be solved directly, others require Maxwell-construction type
approximations.Comment: 30 pages, 10 figure
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