Dynamic analysis of V-folded cavity for TEM00 operation of end-pumped solid-state laser

Based on graphic analysis design method of optical resonator, a simple design expression of V-folded cavity of end-pumped solid-state lasers with TEM00 operation is described, which satisfies two criterias of the resonator design. We give numerical simulation of spot size as a function of thermal focal length using this design approach whose advantages are validated experimentally.

Nd-glass belt lasers with improved beam quality

Nd-doped phosphate glass belt lasers pumped by laser diodes are demonstrated. The Nd-glass belt with a large cross-section and a small Fresnel number is air-cooled to provide around 18-W continuous wave (CW) output power with a beam quality factor of My2

Theoretical study on longitudinally pumped Yb3+:Y2O3 lasers

To optimize the performance of longitudinally pumped Yb^(3+):Y2O3 ceramic lasers, cavity parameters such as material length and output coupler transmission at a certain laser output power are calculated numerically using quasi-three-level laser model. The results show great potential of Yb^(3+):Y2O3 ceramics for highly efficient diode-pumped solid-state lasers.

110-W fiber laser with homemade double-clad fiber

A high-power ytterbium-doped fiber laser (YDFL) with homemade double-clad fiber (DCF) is introduced in this letter. The geometric parameter and laser characteristics of the fiber have been studied. With one-end-pumping scheme, pumped by a high-power laser diode with launching power of 280 W, a maximum continuous wave (CW) output of 110 W is obtained with an optical-to-optical efficiency of 40%.

Laser-diode-pumped Cr4+,Nd3+: YAG with self-Q-switched laser output of 1.4 W

By use of a laser diode as a pump source, a self-Q-switched laser from a Cr,Nd:YAG crystal is demonstrated. The output Q-switched traces are very stable, the threshold pump power is 3.5 W, the pulse duration is 50 ns, and the slope efficiency is as high as 20%. In addition, the pulse width remains constant while the pulse repetition rate Varies with pump power. (C) 2000 Optical Society of America OCIS codes: 140.0140, 140.2020, 140.3380, 140.3480, 140.3540, 140.3580.

Past 140-year environmental record in the northern South China Sea : evidence from coral skeletal trace metal variations

About 140-year changes in the trace metals in Porites coral samples from two locations in the northern South China Sea were investigated. Results of PCA analyses suggest that near the coast, terrestrial input impacted behavior of trace metals by 28.4%, impact of Sea Surface Temperature (SST) was 19.0%, contribution of war and infrastructure were 14.4% and 15.6% respectively. But for a location in the open sea, contribution of War and SST reached 33.2% and 16.5%, while activities of infrastructure and guano exploration reached 13.2% and 14.7%. While the spatiotemporal change model of Cu, Cd and Pb in seawater of the north area of South China Sea during 1986–1997 were reconstructed. It was found that in the sea area Cu and Cd contaminations were distributed near the coast while areas around Sanya, Hainan had high Pb levels because of the well-developed tourism related activities.

Learning in 140 characters : microblogging for professional learning

This thesis investigated how microblogging, a form of online social networking, was being employed by educators to support their professional learning. The study found that educators who participate in microblogging engage in a wide range of behaviours, with certain behaviours and activities commonly exhibited. An advantage of microblogging as a professional learning tool is its ability to link educators globally to exchange ideas from different perspectives and to share resources and teaching practices. Educators who microblog have access to relevant and timely learning that is not constrained by time or distance and can be tailored to meet their individual needs.

Professional learning in 140 characters

The World Wide Web has grown into a global information and communication space with more than a billion users and has entered a new, more social and participatory phase where people create and manage online content rather than just viewing it; a place where people can communicate knowledge, share resources and participate in social networks. Online social networks are being used to support professional learning where groups of people are using the Web to communicate and collaborate in order to build and share knowledge and form professional learning networks (PLNs). This session will present the results of research into how microblogging, a form of online social networking, is being employed by educators to support their professional learning. The study examined activities and perceptions of a group of educators in order to provide an insight into how and why they engage in microblogging and the value they place on microblogging as a professional learning tool. The session will outline the advantages of microblogging as a professional learning tool; the range of behaviours and activities that are undertaken to support professional learning; and the implications for practice.

Sapientia, 1981, Vol. XXXVI, nº 140 (número completo)

Contenido: Itinerario de la inteligencia a la verdad. I : la realidad del conocimiento / Octavio N. Derisi – Ambigüedades de la metafísica de Aristóteles : en torno a la analogía del ser / Cesáreo López Salgado – Metafísica de los valores / Gustavo E. Ponferrada – La fiabilidad de la ciencia experimental / Mariano Artigas Mayayo – Gilsoniana / Mario E. Sacchi – Notas y comentarios -- Bibliografía

Diário da Constituinte [gravação de vídeo] : [programa n. 140]

Mesa redonda no Anfiteatro da Universidade de Brasília - UNB, reunindo parlamentares cientistas e participantes da 39ª Reunião Anual da Sociedade Brasileira para o Progresso da Ciência (SBPC), que teve como palavra de ordem a pressão popular. Em debate na Reunião da SBPC as perspectivas de avanço com a nova Carta. O Deputado Florestan Fernandes (PT-SP) relata que o atual projeto de Constituição não reflete os interesses da sociedade brasileira. A Deputada Moema São Thiago(PDT-CE) fez apelo para que a sociedade brasileira acompanhe os trabalhos da Assembleia Nacional Constituinte (ANC), sobretudo o voto dos constituintes da sua região. O Deputado José Carlos Sabóia (PMDB-MA) considera que a perspectiva dos constituintes, em relação aos problemas da ciência, da tecnologia, da cultura e da universidade, não é a mesma dos cientistas. Os Deputados Gabriel Guerreiro (PMDB-PA) e Octávio Elísio (PMDB-MG) pedem o esforço da população brasileira para que a nova Constituição seja moderna e progressista. O Deputado Noel de Carvalho (PDT-RJ) afirma que a única chance de mudança é uma grande mobilização popular que "atropele" a Constituinte, antes que a Constituinte "atropele" o povo com uma Constituição que só servirá as elites. O Partido dos Trabalhadores (PT) quer mudar o esquema de discussão em Plenário, de tal forma que se explicite em cada Ordem do Dia o tema a ser debatido. O Deputado Plínio Arruda Sampaio (PT-SP) diz que o seu partido terá que elaborar uma estratégia para fazer aprovar a ideia. O Deputado Lúcio Alcântara (PFL-CE) acredita que possa ser aprovada uma proposta intermediária, mas o acerto terá que ser feito entre os partidos e a Mesa da Assembleia Nacional Constituinte (ANC). O Senador Mauro Benevides (PMDB-CE) esclarece que a proposta do PT não possui amparo regimental e o Presidente da Assembleia Nacional Constituinte (ANC) Ulysses Guimarães não acolheu a sugestão. Na sessão O Povo Pergunta, cidadã quer saber o que a Constituinte está fazendo quanto a segurança da mulher em relação ao crime de estupro. O Deputado José Maurício (PDT-RJ) responde que foi aprovada uma emenda tornando o estupro um crime imprescritível e inafiançável, além de estabelecer que caberá ao Ministério Público, não mais à vítima, fazer a denúncia.

Mastigophora and Rhizopoda found in saline lakes Weissovo and Repnoie (near Slaviansk). Selected passages describing Ochromonas species and Pedinella. [Translation of: Trudy Obshch.Ispyt.Prir.imp.khar'kov.Univ. 21 119-140, 1888]

This translation includes selected passages of a longer paper on Mastigophora and Rhizopoda found in saline lakes Weissovo and Repnoie. The translation focuses on describing taxonomy and morphology of Ochromonas species and Pedinella. Plates and figures of the original paper are not included in the translation.