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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 311: 124007, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38354674

RESUMO

A room temperature line list for the H215O radioactive isotopologue of the water molecule is computed using the variational nuclear-motion DVR3D program suite and an empirical high-precision potential energy function. The line list consists of rotation-vibrational energies and Einstein-A coefficients, covering a wide spectral range from 0 to 25000 cm-1 and the total angular momenta J up to 30. Estimates of air-broadening coefficients are provided. Experimentally derived energies of H216O, H217O and H218O from the literature are used to provide improved energies for important states with uncertainty estimates for the H215O. A number of the wmost promising spectroscopic ranges for the detection of H215O are proposed. The calculated absorption spectrum should be useful for the study gaseous radioactive water at IR region, determining concentration, etc.

2.
Biol Sport ; 40(2): 575-586, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37077782

RESUMO

To assess the mechanisms of ACL injury in male professional football players in Qatar across multiple seasons using systematic video analysis. 15 ACL injuries occurred in competition among the professional football teams that participated in an injury Surveillance Programme during 6 seasons (2013/2014 to 2018/2019). High-definition broadcast videos of these injuries were analyzed (49 views; 34 slow motion) by five analysts who independently described the injury mechanisms (situation, behavior, biomechanical characteristics) using validated observational tools. A knee valgus mechanism was observed in two-thirds of the cases (1 with direct contact to the knee, 3 with indirect contact (other body parts) and 6 with no contact). No visible valgus was reported in 2 of the direct knee contact injuries, while 3 cases of non-contact and indirect contact injuries were unclear. We observed 4 main categories of injury situation among those (n = 12) classified as non-contact/ indirect contact (multiple combinations were possible): pressing (n = 6), tackling or being tackled (n = 4), blocking (n = 3) and screening (n = 2). Direct contact injuries (n = 3) were suffered by 2 players during tackling and 1 whilst being tackled. Contact injuries represented only 20% of ACL injuries occurring during competition in Qatari professional soccer players. Independent of the playing situation, knee valgus was frequently observed (10/15 cases). Pressing was the most common situation (6/15 cases) leading to injury. Landing after heading was not reported in any of these ACL injuries.

3.
J ISAKOS ; 7(1): 19-26, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35543655

RESUMO

The prevalence of isolated meniscal injuries in children and adolescents is low; however, we see an increase mainly due to intensified sports-related activities at an early age. A meniscal repair should be attempted whenever possible as children present with increased meniscal healing potential. The diagnosis and management of meniscal tears involve both patient factors and tear characteristics: size, anatomical location and associated injuries. Special attention should be given to the feature of discoid menisci and related tears as they require a specific management plan. This state-of-the-art review highlights the most recent studies on clinical evaluation, surgical techniques, tips and tricks, pitfalls, outcomes, return-to-sports, geographical differences and future perspectives related to meniscal injuries in children and adolescents.


Assuntos
Doenças das Cartilagens , Menisco , Lesões do Menisco Tibial , Adolescente , Artroscopia/métodos , Criança , Humanos , Meniscos Tibiais/cirurgia , Estudos Retrospectivos , Lesões do Menisco Tibial/diagnóstico , Lesões do Menisco Tibial/epidemiologia , Lesões do Menisco Tibial/cirurgia
4.
Plant Signal Behav ; 15(11): 1805885, 2020 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-32787497

RESUMO

Plants exhibit several restrictions under waterlogging conditions, including stomatal limitations, negative impacts on gas exchange, lower nutrient uptake and reduced growth. 24-epibrassinolide (EBR) is a polyhydroxylated steroid, with the advantages to be a natural and biodegradable molecule, presenting beneficial roles in metabolic and physiological processes. The aim of this research is to investigate whether EBR can protect soybean plants against damage caused by waterlogging and evaluate the responses associated with the root and leaf anatomy, photosynthetic machinery and biomass. This study used a completely randomized factorial design with two water conditions (control and waterlogging) and three concentrations of 24-epibrassinolide (0, 5 and 10 nM EBR). This steroid stimulated the activities of enzymes linked to the antioxidant system and resulted in minor damage to the chloroplast membranes. EBR maximized the efficiency of photosystem II and improved the gas exchange, which was explained by the higher density and index of the stomata in addition to the increased chlorophyll content and electron transport rate. In root structures, EBR mitigated the impact of waterlogging on vascular cylinder and metaxilem, suggesting maintenance and functions of these structures in plants stressed.


Assuntos
Brassinosteroides/farmacologia , Glycine max/efeitos dos fármacos , Glycine max/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Esteroides Heterocíclicos/farmacologia , Biomassa , Fotossíntese/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos
5.
Phys Rev Lett ; 124(13): 133904, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32302192

RESUMO

The mid-infrared atmospheric window of 3-5.5 µm holds valuable information regarding molecular composition and function for fundamental and applied spectroscopy. Using a robust, mode-locked fiber-laser source of <11 fs pulses in the near infrared, we explore quadratic (χ^{(2)}) nonlinear optical processes leading to frequency comb generation across this entire mid-infrared atmospheric window. With experiments and modeling, we demonstrate intrapulse difference frequency generation that yields few-cycle mid-infrared pulses in a single pass through periodically poled lithium niobate. Harmonic and cascaded χ^{(2)} nonlinearities further provide direct access to the carrier-envelope offset frequency of the near infrared driving pulse train. The high frequency stability of the mid-infrared frequency comb is exploited for spectroscopy of acetone and carbonyl sulfide with simultaneous bandwidths exceeding 11 THz and with spectral resolution as high as 0.003 cm^{-1}. The combination of low noise and broad spectral coverage enables detection of trace gases with concentrations in the part-per-billion range.

6.
Sci Adv ; 5(6): eaaw8794, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31187063

RESUMO

Probing matter with light in the mid-infrared provides unique insight into molecular composition, structure, and function with high sensitivity. However, laser spectroscopy in this spectral region lacks the broadband or tunable light sources and efficient detectors available in the visible or near-infrared. We overcome these challenges with an approach that unites a compact source of phase-stable, single-cycle, mid-infrared pulses with room temperature electric field-resolved detection at video rates. The ultrashort pulses correspond to laser frequency combs that span 3 to 27 µm (370 to 3333 cm-1), and are measured with dynamic range of >106 and spectral resolution as high as 0.003 cm-1. We highlight the brightness and coherence of our apparatus with gas-, liquid-, and solid-phase spectroscopy that extends over spectral bandwidths comparable to thermal or infrared synchrotron sources. This unique combination enables powerful avenues for rapid detection of biological, chemical, and physical properties of matter with molecular specificity.

7.
Shoulder Elbow ; 11(2): 106-112, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30936949

RESUMO

BACKGROUND: To evaluate the reliability of the Bare Spot (BS) as an anatomical landmark for the intra-operative definition of bone loss in anterior shoulder instability. METHODS: The distances from the BS to the anterior (BS-A), posterior (BS-P) and inferior margins of the glenoid cavity were determined both under arthroscopic visualization and by an open approach in 20 shoulders. RESULTS: The BS did not coincide with the centre of the glenoid cavity of the studied shoulders because the BS-P distance was greater than the BS-A distance (p < 0.05) and was located 40% closer to the anterior margin. The authors suggest a correction factor: BP-A × 1.25/BP-P = 1. CONCLUSIONS: The BS is located at a mean distance of 40% of the joint diameter, relative to the anterior margin of the glenoid. This point may be used as a landmark, using a correction factor of its mostly anterior positioning. Arthroscopy was reliable for bone measurements of the shoulder joint.

8.
Biosci. j. (Online) ; 34(6): 1593-1602, nov.-dec. 2018. tab
Artigo em Inglês | LILACS | ID: biblio-968958

RESUMO

The faveira bean (Parkia platycephala Benth.), belongs to the Fabaceae family, this species is recommended for afforestation and also has a forage potential. In addition, it has the potential of landscaping, the wood can be used for box-office, tables for internal divisions in small constructions, linings, confection of toys, as well as for firewood and charcoal. That way, the aim of this study was to evaluate the effect of different temperature and substrate on the germination of seeds of P. platycephala. The study was carried out at the laboratory for analysis of Seeds of the Department of Plant Science and Environmental Agricultural Sciences Center of the da Universidade Federal da Paraíba, in Areia - PB. Therefore, a completely randomized design and a 6 x 4 factorial arrangement were performed, consisting of the combinations of six temperatures (25, 30 and 35 °C constant and 20-30, 20-35 and 25-35 °C alternating) and four substrates (sand, coconut fiber, paper and vermiculite). To evaluate the effect of the treatments were performed germination test, first count and germination speed index, length of plants, root and aerial dry matter. The constant temperature of 35 °C provided better performance of seeds Parkia platycephala when using the sand as substrate.


A faveira (Parkia platycephala Benth.), pertence à família Fabaceae, é uma espécie recomendada para arborização e também possui potencial forrageiro. Além disso, tem potencial paisagístico, a madeira pode ser utilizada para caixotaria, tabuados para divisões internas em pequenas construções, forros, confecção de brinquedos, bem como para lenha e carvão. Dessa forma, o trabalho objetivou avaliar o efeito de diferentes temperaturas e substratos na germinação de sementes de P. platycephala. O mesmo foi realizado no Laboratório de Análise de Sementes, do Departamento de Fitotecnia e Ciências Ambientais do Centro de Ciências Agrárias da Universidade Federal da Paraíba, no município de Areia, PB. Portanto, realizou-se experimento em delineamento inteiramente ao acaso e arranjo fatorial 6 x 4, constituídos pelas combinações de seis temperaturas (25, 30 e 35 °C constantes e 20-30, 20-35 e 25-35 °C alternadas) e quatro substratos (areia, fibra de coco, papel e vermiculita). Para avaliação dos tratamentos realizou-se testes de germinação e vigor (primeira contagem e índice de velocidade de germinação, bem como o comprimento e massa seca das raízes e parte área). O substrato areia na temperatura de 35 °C é recomendado para testes de germinação e vigor em sementes de Parkia platycephala.


Assuntos
Sementes , Substratos para Tratamento Biológico , Germinação , Fabaceae
9.
Biosci. j. (Online) ; 34(6): 1603-1610, nov.-dec. 2018. graf
Artigo em Inglês | LILACS | ID: biblio-968959

RESUMO

The species Enterolobium contortisiliquum (Vell.) Morong., (Fabaceae) is widely distributed in Brazil, commonly found in the Atlantic Forest domain. Despite its importance for the ecosystems, studies based on storage of E. contortisiliquum seeds are scarce. The objective of this work was to evaluate the physiological quality of seeds of Enterolobium contortisiliquum stored in different packages, environments and storage periods. The seeds were obtained from ripe fruits at the beginning of the natural dispersion in seven selected trees, located in the municipality of Areia - Paraíba, between the months of November and December 2010 and then taken to the laboratory for analysis of Seeds of the Department of Plant Science and Environmental Agricultural Sciences Center of the Universidade Federal da Paraíba. A completely randomized design was used, with subdivided plots, being the major portion constituted by environments (lab, cold storage chamber, freezer and fridge), a sub-plot for the packages (kraft paper bag, cloth, aluminum, plastic (PP) and PET bottle) and the sub plot constituted by the storage periods (0, 30, 60, 90, 120, 150, 180, 210, 240 and 270 days). For the evaluation of physiological quality was determined by water content, percentage of emergence, length and dry weight of shoots and roots. The packing of seeds ofE. contortisiliquum can be made in polypropylene plastic bags (PP) and they can be stored under natural laboratory environment for 270 days with no decrease of seed vigor.


A espécie Enterolobium contortisiliquum (Vell.) Morong., (Fabaceae) tem ampla ocorrência noBrasil, especialmente no domínio de Mata Atlântica. Apesar de sua importância na dinâmica dos ecossistemas, os estudos sobre o armazenamento de suas sementes são escassos. Dessa forma, o objetivo do trabalho foi avaliar a qualidade fisiológica de sementes de Enterolobium contortisiliquum armazenadas em diferentes embalagens, ambientes e períodos de armazenamento. As sementes foram obtidas de frutos maduros no inicio da dispersão natural em sete árvores matrizes localizadas no município de Areia - PB, entre os meses de novembro e dezembro de 2010 e, em seguida, levados ao Laboratório de Análise de Sementes do Departamento de Fitotecnia e Ciências Ambientais do Centro de Ciências Agrárias da Universidade Federal da Paraíba. O delineamento foi inteiramente ao acaso em parcela subsubdividida, sendo a parcela principal constituída pelos ambientes (laboratório, câmara fria, freezer e geladeira), a subparcela pelas embalagens (papel kraft, pano, alumínio, plástico (PP) e garrafa PET) e a subsubparcela constituída pelos períodos de armazenamento (0, 30, 60, 90, 120, 150, 180, 210, 240 e 270 dias). Para avaliação da qualidade fisiológica determinou-se o teor de água, porcentagem de emergência, comprimento e massa seca de parte aérea e raízes. As sementes de E. contortisiliquumpodem ser acondicionadas em embalagem de saco de plástico de polipropileno (PP) e armazenadas em ambiente natural de laboratório durante 270 dias sem redução no vigor.


Assuntos
Sementes , Florestas , Germinação , Conservação dos Recursos Naturais
10.
Biosci. j. (Online) ; 34(6): 1611-1621, nov.-dec. 2018. graf
Artigo em Inglês | LILACS | ID: biblio-968960

RESUMO

The Dimorphandra gardneriana Tul. species is widely distributed in the Brazilian territory presenting an economic and environmental importance. The aim of this study was to determine the fungi associated with Dimorphandra gardneriana seeds, assessing the influence of nystatin, the castor oil plant and Captan® fungicide in the control of these fungi in the seed germination and seedlings growth. The experiment was carried out at the Laboratório de Fitopatologia and Análise de Sementes of the Departamento de Fitotecnia e Ciências Ambientais of Centro de Ciências Agrárias of the Universidade Federal da Paraíba, Areia-PB, Brazil. Ten treatments were applied for mycoflora control: T1 - control (untreated seeds); T2 - nystatin (0.1%); T3 - nystatin (0.2%); T4 - nystatin (0.3%); T5 - nystatin (0.4%); T6 - castor bean oil (0.25%); T7 - castor bean oil (0.5%); T8 - castor bean oil (0.75%); T9 - castor bean oil (1%); T10 - fungicide Captan®. For the evaluation of the effect of the treatments on the Dimorphandra gardneriana seeds the following variables were evaluated: germination, first counting of germinationand germination speed index, percentage of abnormal seedlings, length and dry matter of shoots and roots of seedlings. Nystatin (0.1%) reduced the incidence of Aspergillus sp. The Captan® fungicide reduced the incidence of fungi in the seeds and provided the best results for germination and vigor.


A espécie Dimorphandra gardneriana Tul. tem ampla distribuição no território brasileiro, apresentando importância econômica e ambiental. O objetivo desse trabalho foi verificar quais fungos estão associados a sementes de Dimorphandra gardneriana, avaliando a influência da nistatina, do óleo de rícino e do fungicida Captan®, no controle desses fungos, na germinação de sementes e no crescimento de plântulas. O experimento foi realizado nos Laboratórios de Fitopatologia e de Análise de Sementes do Departamento de Fitotecnia e Ciências Ambientais do Centro de Ciências Agrárias da Universidade Federal da Paraíba, Areia-PB, Brasil. No controle da micoflora foram aplicados 10 tratamentos, a saber: T1 - testemunha (sementes não tratadas); T2 - nistatina (0,1%); T3 - nistatina (0,2%); T4 - nistatina (0,3%); T5 - nistatina (0,4%); T6 - óleo de rícino (0,25%); T7 - óleo de rícino (0,5%); T8 - óleo de rícino (0,75%); T9 - óleo de rícino (1%); T10 - fungicida Captan®. Para avaliar o efeito dos tratamentos sobre as sementes de Dimorphandra gardneriana foram avaliadas as variáveis: germinação, primeira contagem de germinação e índice de velocidade de germinação, porcentagem de plântulas anormais, comprimento e massa seca da parte aérea e de raízes de plântulas. A nistatina (0,1%) diminuiu a incidência de Aspergillus sp. O fungicida Captan® reduziu a incidência de fungos nas sementes da espécie e proporcionou os melhores resultados para germinação e vigor.


Assuntos
Sementes , Germinação , Fungos
11.
Opt Lett ; 43(8): 1678-1681, 2018 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-29652338

RESUMO

We experimentally demonstrate a simple configuration for mid-infrared (MIR) frequency comb generation in quasi-phase-matched lithium niobate waveguides using the cascaded-χ(2) nonlinearity. With nanojoule-scale pulses from an Er:fiber laser, we observe octave-spanning supercontinuum in the near-infrared with dispersive wave generation in the 2.5-3 µm region and intrapulse difference frequency generation in the 4-5 µm region. By engineering the quasi-phase-matched grating profiles, tunable, narrowband MIR and broadband MIR spectra are both observed in this geometry. Finally, we perform numerical modeling using a nonlinear envelope equation, which shows good quantitative agreement with the experiment-and can be used to inform waveguide designs to tailor the MIR frequency combs. Our results identify a path to a simple single-branch approach to mid-infrared frequency comb generation in a compact platform using commercial Er:fiber technology.

12.
J Plant Physiol ; 221: 11-21, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29223878

RESUMO

Plants are sessile organisms that must perceive and respond to various environmental constraints throughout their life cycle. Among these constraints, drought stress has become the main limiting factor to crop production around the world. Water deprivation is perceived primarily by the roots, which efficiently signal the shoot to trigger drought responses in order to maximize a plant's ability to survive. In this study, the tomato (Solanum lycopersicum L.) mutant procera (pro), with a constitutive response to gibberellin (GA), and its near isogenic line cv. Micro-Tom (MT), were used in reciprocal grafting under well-watered and water stress conditions to evaluate the role of GA signaling in root-to-shoot communication during drought stress. Growth, oxidative stress, gene expression, water relations and hormonal content were measured in order to provide insights into GA-mediated adjustments to water stress. All graft combinations with pro (i.e. pro/pro, MT/pro and pro/MT) prevented the reduction of growth under stress conditions without a reduction in oxidative stress. The increase of oxidative stress was followed by upregulation of SlDREB2, a drought-tolerance related gene, in all drought-stressed plants. Scions harboring the pro mutation tended to increase the abscisic acid (ABA) content, independent of the rootstock. Moreover, the GA sensitivity of the rootstock modulated stomatal conductance and water use efficiency under drought stress, indicating GA and ABA crosstalk in the adjustment of growth and water economy.


Assuntos
Secas , Giberelinas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Raízes de Plantas/metabolismo , Solanum lycopersicum/fisiologia , Regulação da Expressão Gênica , Solanum lycopersicum/genética , Proteínas de Plantas/metabolismo , Brotos de Planta/metabolismo
13.
Opt Express ; 24(26): 30100-30107, 2016 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-28059288

RESUMO

Terahertz dual frequency comb spectroscopy (THz-DFCS) yields high spectral resolution without compromising bandwidth. Nonetheless, the resolution of THz-DFCS is usually limited by the laser repetition rate, which is typically between 80 MHz and 1 GHz. In this paper, we demonstrate a new method to achieve sub-repetition rate resolution in THz-DFCS by adaptively modifying the effective laser repetition rate using integrated Mach-Zehnder electro-optic modulators (MZ-EOMs). Our results demonstrate that it is possible to improve the 100 MHz resolution of a terahertz frequency comb by at least 20x (down to 5 MHz) across the terahertz spectrum without compromising the average output power, and to a large extent, its bandwidth. Our approach can augment a wide range of existing THz-DFCS systems to provide a significant and easily adaptable resolution improvement.

14.
Opt Express ; 23(20): 26814-24, 2015 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-26480192

RESUMO

Mid-infrared femtosecond optical frequency combs were produced by difference frequency generation of the spectral components of a near-infrared comb in a 3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB parametric gain in the 1.5 µm signal, which yields powers above 500 mW (3 µW/mode) in the idler with spectra covering 2.8 µm to 3.5 µm. Potential for broadband, high-resolution molecular spectroscopy is demonstrated by absorption spectra and interferograms obtained by heterodyning two combs.

15.
Biosci. j. (Online) ; 29(4): 859-866, july/aug. 2013. tab
Artigo em Português | LILACS | ID: biblio-914700

RESUMO

A semente é insumo básico que deve atender aos requisitos de qualidade fisiológica para garantir o estabelecimento de cultivos com alta produtividade. O presente trabalho teve como objetivo avaliar a eficiência de métodos que permitam separar as sementes em níveis de vigor, sendo utilizados para isso, quatro lotes de sementes de Amburana cearensis (Allemão) A.C. Smith (cumaru). As variáveis analisadas foram: teor de água, o peso de 1.000 sementes, porcentagem de germinação, emergência em campo, índice de velocidade de germinação e de emergência, comprimento e massa seca de plântulas do laboratório e campo. O peso de mil sementes não permitiu a separação dos lotes de sementes de A. cearensis em níveis de vigor, enquanto os testes de campo (emergência de plântulas, primeira contagem, índice de velocidade de emergência, comprimento e a massa seca das plântulas) são eficientes na separação dos lotes de sementes de A. cearensis em níveis de vigor.


Seed is the basic input, so requirements of physiological quality to guarantee the establishment of cultivations with high productivity is essential. This study aimed to evaluate the effectiveness of methods to separate the seeds at levels of vigour being used to it, four seed lots Amburana cearensis (Allemão) AC Smith (cumaru). In four lots of A. cearensis seeds were evaluated water content, weight of 1000 seeds, germination, field seedling emergence, index of germination speed and index emergence speed, and length and dry mass of seedlings from both the laboratory and from the field. The weight of 1000 seeds did not allowed the separation of the lots in vigor levels. Field tests (seedling emergence, first count, speed emergence index, length and dry mass of the seedlings) are efficient in the separation of the seed lots of A. cearensis in vigor levels.


Assuntos
Sementes , Sementes/fisiologia , Germinação , Dipteryx
16.
Opt Express ; 16(19): 15109-14, 2008 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-18795049

RESUMO

The asynchronous transmission (encoding and decoding) of 64-bit information using binary spectral phase shaping is demonstrated. The accurate introduction and retrieval of the binary information is possible by using multiphoton intrapulse interference phase scan (MIIPS) to measure and correct the spectral phase distortions of the laser and the transmission media. Experimental demonstration is achieved using a sub-6 fs Ti:Sapphire laser with 2.12-GHz repetition rate and an adaptive phase control system.


Assuntos
Desenho Assistido por Computador , Lasers , Modelos Teóricos , Medidas de Segurança , Processamento de Sinais Assistido por Computador/instrumentação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento
17.
Opt Express ; 16(17): 13267-75, 2008 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-18711563

RESUMO

Optical frequency combs generated by multiple four-wave mixing in short and highly nonlinear optical fibers are proposed for use as high precision frequency markers, calibration of astrophysical spectrometers, broadband spectroscopy and metrology. Implementations can involve two optical frequency standards as input lasers, or one standard and a second laser phase-locked to it using a stable microwave reference oscillator. Energy and momentum conservation required by the parametric generation assures phase coherence among comb frequencies, while fibers with short lengths can avoid linewidth broadening and stimulated Brillouin scattering. In contrast to combs from mode-locked lasers or microcavities, the absence of a resonator allows large tuning of the frequency spacing from tens of gigahertz to beyond teraHertz.


Assuntos
Astronomia/instrumentação , Tecnologia de Fibra Óptica/instrumentação , Filtração/instrumentação , Óptica e Fotônica/instrumentação , Análise Espectral/instrumentação , Astronomia/normas , Calibragem , Desenho de Equipamento , Análise de Falha de Equipamento , Tecnologia de Fibra Óptica/normas , Filtração/métodos , Raios Infravermelhos , Micro-Ondas , Fibras Ópticas , Análise Espectral/normas
18.
Opt Express ; 16(14): 10033-8, 2008 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-18607410

RESUMO

We report a self-starting prismless femtosecond Ti:sapphire ring laser whose repetition rate has been gradually increased from 1 to 2.12 GHz. A broadband spectrum extending from 650 to 1040 nm, in which 17% of the intracavity power is generated in a single-pass through the crystal, is preserved in spite of the reduction in peak power. An average power of 0.95 W was obtained for 7.5 W of pump power, with very stable operation verified over 22 hours. Pulses from this laser have been fully characterized in spectral phase, and then compressed to 5.9 femtoseconds using multiphoton intrapulse interference phase scan (MIIPS).

19.
Opt Express ; 16(5): 2909-14, 2008 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-18542375

RESUMO

We describe a setup for a deep optical dipole trap or lattice designed for holding atoms at temperatures of a few mK, such as alkaline-Earth atoms which have undergone only regular Doppler cooling. We use an external optical cavity to amplify 3.2 W from a commercial single-frequency laser at 532 nm to 523 W. Powers of a few kW, attainable with low-loss optics or higher input powers, allow larger trap volumes for improved atom transfer from magneto-optical traps. We analyze possibilities for cooling inside the deep trap, the induced Stark shifts for calcium, and a cancellation scheme for the intercombination clock transition using an auxiliary laser.


Assuntos
Álcalis/química , Álcalis/efeitos da radiação , Temperatura Baixa , Lasers , Modelos Teóricos , Pinças Ópticas , Óptica e Fotônica/instrumentação , Transdutores , Simulação por Computador
20.
Opt Express ; 15(19): 11913-21, 2007 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-19547554

RESUMO

We report on continuous-wave second harmonic generation of near infrared Ti:sapphire lasers using room temperature critically phase-matched, angle-tuned BIBO (bismuth triborate, BiB(3)O(6)) crystals, placed both in an external power enhancement cavity and inside the laser resonator. In the first case we generate 70 mW of single-frequency radiation at 423 nm for 330 mW of input power at 846 nm. For intracavity frequency doubling we achieve 690 mW at 423 nm for 7.3 Watts of the Ti:sapphire laser pump power at 532 nm, representing a conversion efficiency of 9.5% from 532 to 423 nm. These tunable blue-violet systems are particularly attractive for laser cooling and trapping of alkaline-Earth atoms.

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