Search results for "RAV"
showing 10 items of 5866 documents
Airy-function approach to binary black hole merger waveforms: The fold-caustic diffraction model
2022
From numerical simulations of the Einstein equations, and also from gravitational wave observations, the gravitational wave signal from a binary black hole merger is seen to be simple and to possess certain universal features. The simplicity is somewhat surprising given that non-linearities of general relativity are thought to play an important role at the merger. The universal features include an increasing amplitude as we approach the merger, where transition from an oscillatory to a damped regime occurs in a pattern apparently oblivious to the initial conditions. We propose an Airy-function pattern to model the binary black hole (BBH) merger waveform, focusing on accounting for its simpl…
The dawning of the theory of equilibrium figures: a brief historical account from the 16th through the 20th century
2014
A very brief historical survey of the theory of equilibrium figures is outlined, from the early origins, dating back to the late 1500s, until up the latest 20th century developments. A seen toward physical applications, ranging from relativistic astrophysics through nuclear physics, is also provided.
Ceļojumu aprakstu izdošanas tradīcijas latviešu grāmatniecībā
2015
Lai gan ceļojumu literatūra ieņem savu noteiktu vietu gan veikalu, gan bibliotēku grāmatu plauktos, ceļojumu aprakstu izdošana un to ietekme uz lasītājiem, ir maz pētīts temats. Līdz šim nav apkopots visu izdoto ceļojumu aprakstu izdevumu klāsts Latvijā. Pētījuma mērķis ir izpētīt ceļojumu aprakstu izdevumu izdošanas tradīcijas Latvijā, kā arī apkopot Latvijā izdotos ceļojumu aprakstu izdevumus, salīdzināt latviešu un ārzemju ceļojumu izdevumus un to īpatsvaru. Darba ietvaros tika analizētas ceļojumu aprakstu definīcijas. Darba gaitā tiek veidota ceļojumu aprakstu grāmatu bibliogrāfija laika posmam no 1991.gada līdz 2014.gadam. Izveidotā bibliogrāfija to veido 106 Latvijā ceļojumu aprakstu …
Unethical Brotherly Love: Zell Kravinsky and Maximum Human Utility
2014
The case of American investor and philanthropist Zell Kravinsky (1956-) presents numerous ethical challenges regarding our social responsibility to others. In 2003, after disbursing the bulk of his forty-five-million-dollar fortune to various charities, Kravinsky made the decision to donate one of his kidneys to an impoverished African-American woman he had met only once. In doing so he courageously saved a life, but also incurred the wrath of his family, friends, and many observers in the media who questioned his sanity. To Kravinsky, however, refusal to donate would have been tantamount to murder, constituting a violation of his belief in ‘maximum human utility’ – a concept that insists o…
Molecular structures and vibrations of m-methylaniline in the S0 and S1 states studied by laser induced fluorescence spectroscopy and ab initio calcu…
2000
Abstract The UV fluorescence excitation and dispersed fluorescence spectra of a jet-cooled m-methylaniline have been obtained for the S1←S0 transition, in which some of the bands have been observed for the first time. The main spectral bands have been assigned by comparison with those of other relevant substituted benzenes. It was found that the spectra exhibit an important feature which is the internal rotation of the methyl group in the electronic ground and excited states. Ab initio calculations at MP2/6-31G* and CIS/6-31G* show that the optimized structure of m-methylaniline in the ground state is not planar with the amino group having sp3 hybridation-like character due to the existence…
Chemical and pharmaceutical evaluation of the relationship between triazole linkers and pore size on cyclodextrin–calixarene nanosponges used as carr…
2016
Mixed cyclodextrin–calixarene nanosponges were used to prepare some composites with the well known polyphenolic bioactive compounds quercetin and silibinin. The composites were characterized by means of different techniques (UV-vis, FT-IR, microcalorimetry, thermogravimetry), in order to assess their loading and thermal stability. The kinetics of release of the bioactive molecules into aqueous solution were studied at two different pH values (1.0, 6.4), which mimic typical physiological conditions. Finally the possible antiproliferative effects in vitro were assayed towards three triple negative breast cancer cell lines (SUM 149, SUM 159 and MDA-MB-23). Our results point out the role assume…
An electrochemical impedance and ac-electrogravimetry study of PNR films in aqueous salt media
2002
Electrochemical impedance spectra and ac-eletrogravimetry of poly(neutral red) films are studied in different aqueous media. The dependence of these experimental data on the nature of alkaline cation and monovalent anion present in the solution and on the pH is analysed. During the electrochemical processes, it is observed that all three species—the salt cation, the salt anion and the hydronium ion—participate to balance the electrical charge within the film. It is also possible to conclude that the participation of anions takes place faster than hydronium ions participation. Besides, the relative participation of these species is related to the pH of the solution. Keywords: Poly (neutral r…
Kinetic and Mechanistic Aspects of a Poly(o-toluidine)-Modified Gold Electrode. 1. Simultaneous Cyclic Spectroelectrochemistry and Electrogravimetry …
2012
International audience; Electrodeposited poly(o-toluidine) (POT) on gold electrodes was investigated in a 0.5 M H2SO4 aqueous solution using cyclic electrogravimetry with in situ vis-NIR spectroscopy. This coupling of different techniques allows the electrical, color, and mass changes during the electrochemical reactions of these polymers to be correlated. Therefore, this is a powerful tool to obtain valuable information on the physical models of polymer films and their electrochemical properties. The accurate analysis of the results from these techniques showed the contribution of three different redox transitions (leucoemeraldine-polaron transition, polaron-bipolaron transition, and bipol…
EFFECTS OF SENSITIZED AND UNSENSITIZED LONGWAVE U.V.-IRRADIATION ON THE SOLUTION PROPERTIES OF DNA
1971
— Two types of photoreactions occur in DNA irradiated in aqueous systems with longwave u.v.-light (Λ > 295 nm), namely, (a) thymine dimerization, and (b) single- and double-strand breakage of the sugar phosphate backbone; these two reactions are unrelated. The presence of acetophenone as a photosensitizer caused an increase in dimerization by a factor of 16, and an increase in single-strand breaks by a factor of 4. The number of thymine dimers per single-strand break is about 100 in the sensitized and 25 in the unsensitized reaction. The alteration of the radius of gyration of DNA molecules is that expected by the degradation observed. At the same time the change in hyperchromicity is very …
1978
A reaction vessel automatically controlled by magnetic valves is described which allows kinetic measurements of reactions with half lives t1/2≥2s by gravimetric determination of the conversion. Thus, it covers the gap between the flow tube and the conventional reaction vessel. The influence of mixing time and filling time on the molecular weight distribution of an anionically prepared polymer is discussed.