979 resultados para Bat trapping


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Honako lan honekin Gobernuz Kanpoko Erakunde (GKE) ezberdinek ingurune txiroak diren lurraldeetan aurkeztu ohi dituzten garapenerako kooperazioko proiektuen analisi bat azaleratuko da, heziketa fisiko, jarduera fisiko, ariketa fisiko edota kirola oinarri bezala duten proiektuetan zentraturik. Lehenago hala ere, garapenerako kooperazioak inguratzen dituen hainbat datu interesgarri argitu nahian, marko teoriko bat ere aurkeztuko da.

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We analyse the physical origin of population inversion via continuous wave two-colour coherent excitation in three-level systems by dressing the inverted transition. Two different mechanisms are identified as being responsible for the population inversion. For V-configured systems and cascade (E) configured systems with inversion on the lower transition, the responsible mechanism is the selective trapping of dressed states, and the population inversion approaches the ideal value of 1. For Lambda-configured systems and Xi-configured systems with inversion on the upper transition, population inversion is based on the selective excitation of dressed states, with the population inversion tending towards 0.5. As the essential difference between these two mechanisms, the selective trapping of dressed states occurs in systems with strong decay into dressed states while the selective excitation appears in systems with strong decay out of dressed states.

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Errebisio bibliografiko honen bitartez erresistentziaren entrenamendurako erabiltzen diren metodo nagusien eragin fisiologikoak ezagutu nahi dira.Lana metodo ezberdinen aurkezpen eta sailkapen batekin hasiko da. Gero metodo jarraien errendimenduko eraginak ikusiko dira, eragin fisiologikoekin batera. Berdina egingo da metodo interbalikoarekin eta sprint metodoarekin. Jarraian erresistentzia entrenamenduaren periodizaziorako modelo ezberdinak ikusiko dira, bakoitzak dituen onura eta arazoekin. Seinale molekularren funtzionamenduaren azalpen labur bat egingo da jarraian, egokitzapen prozesuekin duen lotura handia dela eta. Bukatzeko, lanaren ondorioa nagusiak eta bertatik ateratako gomendio praktikoak ere eskuragarri dituzue.

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Proiektu honetan, esku pilotan jokatzen duten profesionalen desplazamenduen abiadura hobetzeko proposamen bat egin da. Honela, lanaren lehenengo zatia funtsean teorikoa da, baina oso garrantzitsua izango da ondorengo puntu hauek hobetu ulertu ahal izateko: esku pilotaren prestakuntzaren gaur egungo egoera, esku pilotan ematen diren abiadura adierazpen ezberdinak eta desplazamendu abiaduraren ezaugarriak. Ondoren, esku pilotako lekualdatzeei buruz dagoen informazio hutsunea ikusirik, 2 partiduen analisia egin dut, ondoren proposatuko dudan entrenamendua planifikatzeko informazioa jasotzeko. Horretarako, sorturiko behaketa tresna eta analisia egiteko modua azalduz. Azkenik, entrenamendu proposamen bat egiten dut, modu praktiko batean, landu beharreko giharren eta eragina duten ahalmen fisiko ezberdinak kontuan hartuz.

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Lan honetan gizakion korrika eraren eta eboluzuioaren jarraipen bat egin. Gainera gaur egungo lasterketa teknika ezberdinen arteko ekonomia aztertu da.

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The condensation of phenanthroline-5,6-dione (phendione) with polyamines is a versatile synthetic route to a wide variety of chelating ligands. Condensation with 2,3- napthalene diamine gives benzo[i]dipyrido[3,2-a:2',3'-c]phenazine (bdppz) a ligand containing weakly-coupled orbitals of benzophenazine (bpz) and 2,2' -bipyridinde(bpy) character. The bpy character gives Re and Ru complexes excited-state redox properties; intramolecular electron transfer (ET) takes place to the bpz portion of the ligand. The charge-separated state so produced has an extraordinarily-long 50 µs lifetime. The slow rate of charge recombination arises from a combination of extremely weak coupling between the metal center and the bpz acceptor orbital and Marcus "inverted region" behavior. Molecular orbital calculations show that only 3% the electron density in the lowest unoccupied molecular orbital lies on the bpy atoms of bdppz, effectively trapping the transferred electron on the bpz portion. The rate of charge recombination decreases with increasing driving force, showing that these rates lie in the inverted region. Comparison of forward and back ET rates shows that donor-acceptor coupling is four orders of magnitude greater for photoinduced electron transfer than it is for thermal charge recombination.

Condensation of phendione with itself or tetramines gives a series of binucleating tetrapyridophenazine ligands of incrementally-varying coordination-site separation. When a photoredox-active metal center is attached, excited-state energy and electron transfer to an acceptor metal center at the other coordination site can be studied as a function of distance. A variety of monometallic and homo- and heterodimetallic tetrapyridophenazine complexes has been synthesized. Electro- and magnetochemistry show that no ground-state interaction exists between the metals in bimetallic complexes. Excited-state energy and electron transfer, however, takes place at rates which are invariant with increasing donor-acceptor separation, indicating that a very efficient coupling mechanism is at work. Theory and experiment have suggested that such behavior might exist in extended π-systems like those presented by these ligands.

Condensation of three equivalents of 4,5-dimethyl-1,2-phenylenediamine with hexaketocyclohexane gives the trinucleating ligand hexaazahexamethyltrinapthalene (hhtn). Attaching two photredox-active metal centers and a third catalytic center to hhtn provides means by which multielectron photocatalyzed reactions might be carried out. The coordination properties of hhtn have been examined; X-ray crystallographic structure determination shows that the ligand's constricted coordination pocket leads to distorted geometries in its mono- and dimetallic derivatives.

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A novel spectroscopy of trapped ions is proposed which will bring single-ion detection sensitivity to the observation of magnetic resonance spectra. The approaches developed here are aimed at resolving one of the fundamental problems of molecular spectroscopy, the apparent incompatibility in existing techniques between high information content (and therefore good species discrimination) and high sensitivity. Methods for studying both electron spin resonance (ESR) and nuclear magnetic resonance (NMR) are designed. They assume established methods for trapping ions in high magnetic field and observing the trapping frequencies with high resolution (<1 Hz) and sensitivity (single ion) by electrical means. The introduction of a magnetic bottle field gradient couples the spin and spatial motions together and leads to a small spin-dependent force on the ion, which has been exploited by Dehmelt to observe directly the perturbation of the ground-state electron's axial frequency by its spin magnetic moment.

A series of fundamental innovations is described m order to extend magnetic resonance to the higher masses of molecular ions (100 amu = 2x 10^5 electron masses) and smaller magnetic moments (nuclear moments = 10^(-3) of the electron moment). First, it is demonstrated how time-domain trapping frequency observations before and after magnetic resonance can be used to make cooling of the particle to its ground state unnecessary. Second, adiabatic cycling of the magnetic bottle off between detection periods is shown to be practical and to allow high-resolution magnetic resonance to be encoded pointwise as the presence or absence of trapping frequency shifts. Third, methods of inducing spindependent work on the ion orbits with magnetic field gradients and Larmor frequency irradiation are proposed which greatly amplify the attainable shifts in trapping frequency.

The dissertation explores the basic concepts behind ion trapping, adopting a variety of classical, semiclassical, numerical, and quantum mechanical approaches to derive spin-dependent effects, design experimental sequences, and corroborate results from one approach with those from another. The first proposal presented builds on Dehmelt's experiment by combining a "before and after" detection sequence with novel signal processing to reveal ESR spectra. A more powerful technique for ESR is then designed which uses axially synchronized spin transitions to perform spin-dependent work in the presence of a magnetic bottle, which also converts axial amplitude changes into cyclotron frequency shifts. A third use of the magnetic bottle is to selectively trap ions with small initial kinetic energy. A dechirping algorithm corrects for undesired frequency shifts associated with damping by the measurement process.

The most general approach presented is spin-locked internally resonant ion cyclotron excitation, a true continuous Stern-Gerlach effect. A magnetic field gradient modulated at both the Larmor and cyclotron frequencies is devised which leads to cyclotron acceleration proportional to the transverse magnetic moment of a coherent state of the particle and radiation field. A preferred method of using this to observe NMR as an axial frequency shift is described in detail. In the course of this derivation, a new quantum mechanical description of ion cyclotron resonance is presented which is easily combined with spin degrees of freedom to provide a full description of the proposals.

Practical, technical, and experimental issues surrounding the feasibility of the proposals are addressed throughout the dissertation. Numerical ion trajectory simulations and analytical models are used to predict the effectiveness of the new designs as well as their sensitivity and resolution. These checks on the methods proposed provide convincing evidence of their promise in extending the wealth of magnetic resonance information to the study of collisionless ions via single-ion spectroscopy.

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Bloke eskalada modalitatea bere osotasunean aztertzea oso erabilgarria izango da entrenamenduaren planifikazioa modu egokian egiteko. Badaude gai honi buruzko zenbait liburu eta artikulu, baina modalitateko eskakizun guztiak batzen dituen eta zientzian oinarritzen den bat faltan botatzen da. Lanean, eskakizun fisiko, tekniko eta psikologikoak aztertzen dira. Bloke eskaladan gaitasun fisikoak dira gehien aztertutako faktoreak, elementu ezberdinen inguruan datuak eskainiko ditut ondorioz. Arlo tekniko eta batez ere psikologikoan datu gutxiago daude, baina ondorio baliagarriak ateratzeko balio izan dit. Ondorio aipagarrienak atera ditut hurrengo atalean, aipatutako informazioak erlazionatuta bait daude. Bukatzeko, bloke eskaladaren entrenamendurako aspektu garrantzitsuenak identifikatzen dira, modalitate honetako entrenatzaileei literatura zientifikoan oinarritutako zenbait entrenamendu helburu eskaintzeko asmoz.

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Artikulu eta gida askoren literatura azterketa bat burutu da, patologiari buruzko beharrezko informazioa bilatzeko, bularreko minbizia izan dutenengan burutu behar den jarduera fisikoa ezagutzeko eta azkenik, programa fisiko baten garapena burutzeko. Lan honen helburu nagusia, osasunerako eta ongizaterako jarduera fisikoaren eremuan, bularreko minbizia izan duten emakumeentzako jarduera fisikora itzultzeko programa bat sortzea da.

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A theoretical investigation on the nonlinear pulse propagation and dispersive wave generation in the anomalous dispersion region of a microstructured fiber is presented. By simulating the dispersive wave generation under different conditions. it is found that the generation mechanism of the dispersive wave is mainly due to the pulse trapping across the zero-dispersion wavelength. By varying the initial pulse chirp, the output spectrum can be broadened and the intensity of the dispersive wave can be obviously enhanced. In particular, there exists an optimal positive chirp which maximizes the intensity of the dispersive wave. This effect can be explained by the energy transfer from the Raman soliton to the dispersive wave due to the effect of the pulse trapping and the effect of the higher-order dispersion. From the phase aspect, the explanation of this effect is also included. (C) 2004 Elsevier B.V. All rights reserved.

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A theoretical investigation of the nonlinear copropagation of two optical pulses of different frequencies in a photonic crystal fiber is presented. Different phenomena are observed depending on whether the wavelength of the signal pulse is located in the normal or the anomalous dispersion region. In particular, it is found that the phenomenon of pulse trapping occurs when the signal wavelength is located in the normal dispersion region while the pump wavelength is located in the anomalous dispersion region. The signal pulse suffers cross-phase modulation by the Raman shifted soliton pulse and it is trapped and copropagates with the Raman soliton pulse along the fiber. As the input peak power of the pump pulse is increased, the red-shift of the Raman soliton is considerably enhanced with the simultaneous further blue-shift of the trapped pulse to satisfy the condition of group velocity matching.

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The dynamic evolution of a A system coupled by two strong coherent fields is investigated by taking spontaneously generated coherence (SGC) into account. By numericaly simulation, it is shown that the relative phase of the two coherent fields affects significantly the time scale to the coherent population trapping state. In addition, an analytical expression to the evolution rate which is consistent with the numerical results is given. (c) 2005 Elsevier B.V. All rights reserved.

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En este trabajo se dercriben cuales son los efectos del paso del tiempo en el cuerpo humano y como se pueden disminuir o eliminar estos efectos a través de la actividad fisica.

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The field of cavity-optomechanics explores the interaction of light with sound in an ever increasing array of devices. This interaction allows the mechanical system to be both sensed and controlled by the optical system, opening up a wide variety of experiments including the cooling of the mechanical resonator to its quantum mechanical ground state and the squeezing of the optical field upon interaction with the mechanical resonator, to name two.

In this work we explore two very different systems with different types of optomechanical coupling. The first system consists of two microdisk optical resonators stacked on top of each other and separated by a very small slot. The interaction of the disks causes their optical resonance frequencies to be extremely sensitive to the gap between the disks. By careful control of the gap between the disks, the optomechanical coupling can be made to be quadratic to first order which is uncommon in optomechanical systems. With this quadratic coupling the light field is now sensitive to the energy of the mechanical resonator and can directly control the potential energy trapping the mechanical motion. This ability to directly control the spring constant without modifying the energy of the mechanical system, unlike in linear optomechanical coupling, is explored.

Next, the bulk of this thesis deals with a high mechanical frequency optomechanical crystal which is used to coherently convert photons between different frequencies. This is accomplished via the engineered linear optomechanical coupling in these devices. Both classical and quantum systems utilize the interaction of light and matter across a wide range of energies. These systems are often not naturally compatible with one another and require a means of converting photons of dissimilar wavelengths to combine and exploit their different strengths. Here we theoretically propose and experimentally demonstrate coherent wavelength conversion of optical photons using photon-phonon translation in a cavity-optomechanical system. For an engineered silicon optomechanical crystal nanocavity supporting a 4 GHz localized phonon mode, optical signals in a 1.5 MHz bandwidth are coherently converted over a 11.2 THz frequency span between one cavity mode at wavelength 1460 nm and a second cavity mode at 1545 nm with a 93% internal (2% external) peak efficiency. The thermal and quantum limiting noise involved in the conversion process is also analyzed and, in terms of an equivalent photon number signal level, are found to correspond to an internal noise level of only 6 and 4 times 10x^-3 quanta, respectively.

We begin by developing the requisite theoretical background to describe the system. A significant amount of time is then spent describing the fabrication of these silicon nanobeams, with an emphasis on understanding the specifics and motivation. The experimental demonstration of wavelength conversion is then described and analyzed. It is determined that the method of getting photons into the cavity and collected from the cavity is a fundamental limiting factor in the overall efficiency. Finally, a new coupling scheme is designed, fabricated, and tested that provides a means of coupling greater than 90% of photons into and out of the cavity, addressing one of the largest obstacles with the initial wavelength conversion experiment.