Phase control of the Kerr nonlinearity in electromagnetically induced transparency media

We investigate an enhancement of the Kerr nonlinearity in phase-dependent double electromagnetically induced transparency (EIT) media. We find, by changing the relative phase of the driven fields, that the properties of EIT and the Kerr nonlinearity can be modified significantly. Choosing the relative phase appropriately, a giant Kerr nonlinearity can be achieved with vanishing absorptions.

Trichromatic manipulation of Kerr nonlinearity in a three-level lambda atomic system

Trichromatic manipulation of Kerr nonlinearity in a three-level A atomic configuration is investigated theoretically. It is shown that for a weak monochromatic probe field, the enhanced Kerr nonlinearity can be achieved in multiple separate transparent windows due to interference effect of multiple two-photon Raman channels. Furthermore, the property of Kerr nonlinearity can be controlled by the sum of the relative phases of the sideband components of the trichromatic pump field compared to the central component.

Enhancement of Kerr nonlinearity with vanishing absorption in a tripod scheme

The giant enhancement of Kerr nonlinearity in a four-level tripod type system is investigated theoretically. By tuning the value of the Rabi frequency of the coherent control field, owing to the double dark resonances, the giant-enhanced Kerr nonlinearity can be achieved within the right transparency window. The in fluence of Doppler broadening is also discussed.

On Ultrafast Time-Domain TeraHertz Spectroscopy in the Condensed Phase: Linear Spectroscopic Measurements of Hydrogen-Bond Dynamics of Astrochemical Ice Analogs and Nonlinear TeraHertz Kerr Effect Measurements of Vibrational Quantum Beats

Much of the chemistry that affects life on planet Earth occurs in the condensed phase. The TeraHertz (THz) or far-infrared (far-IR) region of the electromagnetic spectrum (from 0.1 THz to 10 THz, 3 cm^-1 to 300 cm^-1, or 3000 μm to 30 μm) has been shown to provide unique possibilities in the study of condensed-phase processes. The goal of this work is to expand the possibilities available in the THz region and undertake new investigations of fundamental interest to chemistry. Since we are fundamentally interested in condensed-phase processes, this thesis focuses on two areas where THz spectroscopy can provide new understanding: astrochemistry and solvation science. To advance these fields, we had to develop new instrumentation that would enable the experiments necessary to answer new questions in either astrochemistry or solvation science. We first developed a new experimental setup capable of studying astrochemical ice analogs in both the TeraHertz (THz), or far-Infrared (far-IR), region (0.3 - 7.5 THz; 10 - 250 cm^-1) and the mid-IR (400 - 4000 cm^-1). The importance of astrochemical ices lies in their key role in the formation of complex organic molecules, such as amino acids and sugars in space. Thus, the instruments are capable of performing variety of spectroscopic studies that can provide especially relevant laboratory data to support astronomical observations from telescopes such as the Herschel Space Telescope, the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the Atacama Large Millimeter Array (ALMA). The experimental apparatus uses a THz time-domain spectrometer, with a 1750/875 nm plasma source and a GaP detector crystal, to cover the bandwidth mentioned above with ~10 GHz (~0.3 cm^-1) resolution.

Using the above instrumentation, experimental spectra of astrochemical ice analogs of water and carbon dioxide in pure, mixed, and layered ices were collected at different temperatures under high vacuum conditions with the goal of investigating the structure of the ice. We tentatively observe a new feature in both amorphous solid water and crystalline water at 33 cm^-1 (1 THz). In addition, our studies of mixed and layered ices show how it is possible to identify the location of carbon dioxide as it segregates within the ice by observing its effect on the THz spectrum of water ice. The THz spectra of mixed and layered ices are further analyzed by fitting their spectra features to those of pure amorphous solid water and crystalline water ice to quantify the effects of temperature changes on structure. From the results of this work, it appears that THz spectroscopy is potentially well suited to study thermal transformations within the ice.

To advance the study of liquids with THz spectroscopy, we developed a new ultrafast nonlinear THz spectroscopic technique: heterodyne-detected, ultrafast THz Kerr effect (TKE) spectroscopy. We implemented a heterodyne-detection scheme into a TKE spectrometer that uses a stilbazoiumbased THz emitter, 4-N,N-dimethylamino-4-N-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS), and high numerical aperture optics which generates THz electric field in excess of 300 kV/cm, in the sample. This allows us to report the first measurement of quantum beats at terahertz (THz) frequencies that result from vibrational coherences initiated by the nonlinear, dipolar interaction of a broadband, high-energy, (sub)picosecond THz pulse with the sample. Our instrument improves on both the frequency coverage, and sensitivity previously reported; it also ensures a backgroundless measurement of the THz Kerr effect in pure liquids. For liquid diiodomethane, we observe a quantum beat at 3.66 THz (122 cm^-1), in exact agreement with the fundamental transition frequency of the υ4 vibration of the molecule. This result provides new insight into dipolar vs. Raman selection rules at terahertz frequencies.

To conclude we discuss future directions for the nonlinear THz spectroscopy in the Blake lab. We report the first results from an experiment using a plasma-based THz source for nonlinear spectroscopy that has the potential to enable nonlinear THz spectra with a sub-100 fs temporal resolution, and how the optics involved in the plasma mechanism can enable THz pulse shaping. Finally, we discuss how a single-shot THz detection scheme could improve the acquisition of THz data and how such a scheme could be implemented in the Blake lab. The instruments developed herein will hopefully remain a part of the groups core competencies and serve as building blocks for the next generation of THz instrumentation that pushes the frontiers of both chemistry and the scientific enterprise as a whole.

Chilodonella cyprini (Moroff, 1902) [Translation from: Izv.gos.nauchno-issled.Inst.ozer.i rech.ryb.kh-va 49 25-28, 1959]

The ciliated protozoan Chilodonella cyprini is described. Chilodon parasitizes the body, gills and fins of fishes. The infusoria produce irritation of the integument and strengthened mucous secretion. The sparse knowledsge of the ecology of chilodon is summarised and some advice on the struggle against cholodoniasis in carp given.

Spatiotemporal instabilities in nonlinear Kerr media in the presence of arbitrary higher-order dispersions

Spatiotemporal instabilities in nonlinear Kerr media with arbitrary higher-order dispersions are studied by use of standard linear-stability analysis. A generic expression for instability growth rate that unifies and expands on previous results for temporal, spatial, and spatiotemporal instabilities is obtained. It is shown that all odd-order dispersions contribute nothing to instability, whereas all even-order dispersions not only affect the conventional instability regions but may also lead to the appearance of new instability regions. The role of fourth-order dispersion in spatiotemporal instabilities is studied exemplificatively to demonstrate the generic results. Numerical simulations confirm the obtained analytic results. (C) 2002 Optical Society of America.

Femtosecond optical Kerr effect study of Ge(10)AS(40)S(30)Se(20) film

The results of the femtosecond optical heterodyne detection of optical Kerr effect at 805 nm with the 80 fs ultrafast pulses in amorphous Ge10As40S30Se20 film is reported in this paper. The film shows an optical non-linear response of: 200 fs under ultrafast 80 fs-pulse excitation and the values of real and imaginary parts of non-linear susceptibility chi((3)) were 9.0 X 10(-12) and -4.0 X 10(-12) esu, respectively. The large third-order non-linearity and ultrafast response are attributed to the ultrafast distortion of the electron orbits surrounding the average positions of the nucleus of Ge, As, S and Se atoms. This Ge10As40S30Se20 chalcogenide glass would be expected as a promising material for optical switching technique. (c) 2005 Elsevier Ltd. All rights reserved.

Ultrafast optical Kerr effect in amorphous Ge10As40S30Se20 film induced by ultrashort laser pulses

The results of the femtosecond optical heterodyne detection of optical Kerr effect at 805 am with the 80 fs ultrafast pulses in amorphous Ge10As40S30Se20 film is reported in this Letter. The film shows an optical nonlinear response of 200 fs under ultrafast 80 fs-pulse excitation, and the values of real and imaginary parts of nonlinear susceptibility chi((3)) were 9.0 x 10(-12) esu and -4.0 x 10(-12) esu respectively. The large third-order nonlinearity and ultrafast response are attributed to the ultrafast distortion of the electron orbits surrounding the average positions of the nucleus of Ge, As, S and Se atoms. This Ge10As40S30Se20 chalcogenide glass would be expected as a promising material for optical switching technique.

Estado e administração no Rio de Janeiro Joanino: a Secretaria do Estado de Negócios do Brasil (1808-1821)

A transmigração da Corte portuguesa para a América no ano de 1808 implicou na transferência de boa parte do aparato administrativo existente em Lisboa, de modo a permitir que o príncipe regente, D. João, pudesse governar o Império, a partir do Rio de Janeiro. Esta tese de doutorado analisa um dos órgãos então estabelecidos: a Secretaria de Estado dos Negócios do Brasil. Partindo-se do princípio de que a dominação se estabelece pela administração, pretendeu-se, pelo estudo dessa instituição, atentar para determinados aspectos que envolveram a instalação dos órgãos de poder no continente americano. Nesse sentido, duas questões nortearam a estruturação e o desenvolvimento dos capítulos deste trabalho. Em um nível mais recortado, atentou-se para um exame sobre as principais caraterísticas da estrutura administrativa dessa instituição, percebendo quem eram os seus oficiais, os cargos ocupados e os seus respectivos ordenados, de modo a compreender as especificidades, o perfil do seu corpo burocrático; bem como a importância desse grupo de funcionários na configuração de um estilo administrativo na nova Corte. No tocante a um âmbito mais amplo, inseriu-se a Secretaria de Estado dos Negócios do Brasil no quadro que a relaciona a outros órgãos de poder então existentes. A partir deste aspecto, tentou-se apreender o eixo da política do príncipe regente para o Brasil. O exame dos tópicos de ação político-administrativa dessa instituição permitiu demonstrar o sentido da administração joanina, durante os quatro primeiros anos de permanência no Rio de Janeiro.

The MLH1 c.1852_1853delinsGC (p.K618A) Variant in Colorectal Cancer: Genetic Association Study in 18,723 Individuals

Colorectal cancer is one of the most frequent neoplasms and an important cause of mortality in the developed world. Mendelian syndromes account for about 5% of the total burden of CRC, being Lynch syndrome and familial adenomatous polyposis the most common forms. Lynch syndrome tumors develop mainly as a consequence of defective DNA mismatch repair associated with germline mutations in MLH1, MSH2, MSH6 and PMS2. A significant proportion of variants identified by screening these genes correspond to missense or noncoding changes without a clear pathogenic consequence, and they are designated as "variants of uncertain significance'', being the c.1852_1853delinsGC (p.K618A) variant in the MLH1 gene a clear example. The implication of this variant as a low-penetrance risk variant for CRC was assessed in the present study by performing a case-control study within a large cohort from the COGENT consortium-COST Action BM1206 including 18,723 individuals (8,055 colorectal cancer cases and 10,668 controls) and a case-only genotype-phenotype correlation with several clinical and pathological characteristics restricted to the Epicolon cohort. Our results showed no involvement of this variant as a low-penetrance variant for colorectal cancer genetic susceptibility and no association with any clinical and pathological characteristics including family history for this neoplasm or Lynch syndrome.

Domus regis: a Casa Real portuguesa no Rio de Janeiro (1808-1821)

Instituição fundamental à monarquia lusitana, a Casa Real portuguesa abrangia, em seu espaço, centenas de criados, homens e mulheres das mais diversas origens. Com a transferência da Corte para o Rio de Janeiro, em 1808, o príncipe regente d. João reestruturou o seu universo doméstico, estabelecendo aqui, e à semelhança de Portugal, todos os departamentos imperativos à correta execução das tarefas cotidianas da sua Casa: cavalariça, cozinha, serviço de copa, câmara, aquisição de gêneros alimentícios, etc. Esta tese tem como objeto a conformação da Casa Real portuguesa no Rio de Janeiro, entre os anos de 1808 e 1821. Serão analisados aqui a estrutura organizacional da Casa Real; os conflitos suscitados entre os recém-emigrados agentes do espaço doméstico régio e os súditos fluminenses; os mecanismos de remuneração peculiares ao universo doméstico joanino; as formas de acesso à Casa Real; e, finalmente, a estrutura financeira da Casa Real portuguesa. Num quadro mais amplo, procurou-se relacionar a Casa do Rei aos outros poderes instituídos na cidade, agora Corte, do Rio de Janeiro, de forma a demonstrar que o espaço doméstico da monarquia era, também, uma instituição relevante na montagem da administração joanina na América e, conseqüentemente, na transformação de um espaço historicamente colonial em centro do império português.

Dos prelos da impressão régia, a cultura científica do período joanino (1808-1821)

O presente estudo examina o momento fundador da imprensa no Brasil em 1808 e a rotina de funcionamento da Impressão Régia, no Rio de Janeiro, entre 1808 e 1821. Qual era sua estrutura administrativa, sua ordem de despesas, a natureza das ocupações funcionais, enfim, qual era a lógica de funcionamento da casa impressora oficial da Corte no início do Oitocentos? Qual o lugar ocupado pelos impressos naquele contexto?Para melhor compreender a estrutura, a rotina administrativa e de funcionamento da Impressão Régia no Rio de Janeiro, mas, principalmente, os usos e funções da régia tipografia no momento de seu estabelecimento por iniciativa do príncipe regente d. João, foi analisada também parte de sua produção, qual seja, os títulos dedicados às Ciências e às Artes. A partir desses livros, localizados no acervo da Biblioteca Nacional do Rio de Janeiro e na Biblioteca Guita e José Mindlin, em São Paulo, foram estudadas as características biobibliográficas de seus autores e a relação dos mesmos com o poder oficial.Foi possível identificar que os autores dos títulos examinados eram herdeiros da tradição ilustrada portuguesa. Partilhando de uma mesma cultura política, possuíam laços estreitos com membros da Corte, prestando obediência ao príncipe, sendo alguns autores, inclusive, integrantes da junta diretora da Impressão Régia.Assim, além da rotina e funcionamento da casa impressora da Corte, no Rio de Janeiro de d. João, o presente trabalho examina tomando como fonte de análise sua produção editorial no campo das Ciências e das Artes a formação da cultura científica do período Joanino e a rede de sociabilidades existente no Rio de Janeiro, entre 1808 e 1821.

Charles Henry Gilbert (1859-1928), Naturalist-in-Charge, and Chauncey Thomas, Jr. (1850-1919), Commanding: Conflict Aboard the U. S. Fish Commission Steamer Albatross in 1902

Charles Henry Gilbert (1859-1928) was a pioneering ichthyologist who made major contributions to the study of fishes of the American West. As chairman of the Department ofZoology at Leland Stanford Junior University in Palo Alto, Calif., during 1891-1925, Gilbert was extremely devoted to his work and showed little patience with those ofa different mindset. While serving as Naturalist-in-Charge of the U.S. Fish Commission Steamer Albatross during her exploratory expedition to the Hawaiian Islands in 1902, Gilbert engaged in an acrimonious feud with the ship's captain, Chauncey Thomas, Jr. (1850-1919), U.S.N., over what Gilbert perceived to be an inadequate effort by the captain. This essay focuses on the conflict between two strong figures, each operatingf rom different world views, and each vying for authority. Despite the difficulties these two men faced, the voyage of the Albatross in 1902 must be considered a success, as reflected by the extensive biological samples collected, the many new species of animals discovered, and the resulting publication of important scientific papers.