Laser induced damage of multi-layer dielectric used in pulse compressor gratings

Laser induced damage threshold (LIDT) of multi-layer dielectric used in pulse compressor gratings (PCG) was investigated. The sample was prepared by e-beam evaporation (EBE). LIDT was detected following ISO standard 11254-1.2. It was found that LIDTs of normal and 51.2 deg. incidence (transverse electric (TE) mode) were 14.14 and 9.31 J/cm2, respectively. A Nomarski microscope was employed to map the damage morphology, and it was found that the damage behavior was pit-concave-plat structure for normal incidence, while it was pit structure for 51.2 deg. incidence with TE mode. The electric field distribution was calculated to illuminate the difference of LIDT between the two incident cases.

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.

Phi 140 mm sapphire crystal growth by temperature gradient techniques and its color centers

Sapphire crystals, 140 mm in diameter and 90 turn in height, have been grown by temperature gradient techniques (TGT). The growth direction of the boule was fixed by means of Lane X-ray diffraction. A prominent 204 nm absorption band in TGT-Al2O3. which does not appear in single crystals grown by Czochralski method has been studied. Analysis further substantiates the F-center model of this band. Two relatively weaker bands absorbing at 232 nm and 254 nm were ascribed to F+ centers. F-type centers concentration was determined using Smakula's equation. (c) 2005 Elsevier B.V. All rights reserved.

Experimental demonstration of a transparent graphene millimetre wave absorber with 28% fractional bandwidth at 140 GHz.

The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz. Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.

Generation of 140 fs pulse train with widely tunable repetition rate through cascaded fibre compression techniques

The authors present numerical simulations of ultrashort pulse generation by a technique of linear spectral broadening in phase modulators and compression in dispersion compensating fibre, followed by a further stage of soliton compression in dispersion shifted fibre. This laser system is predicted to generate pulses of 140 fs duration with a peak power of 1.5 kW over a wide, user selectable repetition rate range while maintaining consistent characteristics of stability and pulse quality. The use of fibre compressors and commercially available modulators is expected to make the system setup compact and cost-effective. © The Institution of Engineering and Technology 2014.

Off-axis sonar beam pattern of free-ranging finless porpoises measured by a stereo pulse event data logger

The off-axis sonar beam patterns of eight free-ranging finless porpoises were measured using attached data logger systems. The transmitted sound pressure level at each beam angle was calculated from the animal's body angle, the water surface echo level, and the swimming depth. The beam pattern of the off-axis signals between 45 and 115 (where 0 corresponds to the on-axis direction) was nearly constant. The sound pressure level of the off-axis signals reached 162 dB re 1 mPa peak-to-peak. The surface echo level received at the animal was over 140 dB, much higher than the auditory threshold level of small odontocetes. Finless porpoises are estimated to be able to receive the surface echoes of off-axis signals even at 50-m depth. Shallow water systems (less than 50-m depth) are the dominant habitat of both oceanic and freshwater populations of this species. Surface echoes may provide porpoises not only with diving depth information but also with information about surface direction and location of obstacles (including prey items) outside the on-axis sector of the sonar beam. 2005 Acoustical Society of America.