521 research outputs found

    Moderate temperature detector development

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    The development of (Hg, Cd)Te detectors for 8 to 12 micrometer wavelength regions capable of achieving significantly improved sensitivity at noncryogenic temperatures is discussed

    Dynamical ultrafast all-optical switching of planar GaAs/AlAs photonic microcavities

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    The authors study the ultrafast switching-on and -off of planar GaAs/AlAs microcavities. Up to 0.8% refractive index changes are achieved by optically exciting free carriers at 1720 nm and a pulse energy of 1.8 micro Joules. The cavity resonance is dynamically tracked by measuring reflectivity versus time delay with tunable laser pulses, and is found to shift by as much as 3.3 linewidths within a few picoseconds. The switching-off occurs with a decay time of around 50 ps. The authors derive the dynamic behavior of the carrier density and of the complex refractive index. They propose that the inferred 10 GHz switching rate may be tenfold improved by optimized sample growth.Comment: 1.) Replaced figure 1 (linear reflectivity) with a more recent and improved measurement 2.) Included a Figure of Merit for switching and compared to other recent contributions 3.) Explained more precisely the effect of embedded Quantum Dots (namely no effect on measurement) 4.) Changed wording in a few place

    Penambahan Naa dan Bap terhadap Multiplikasi Subkultur Tunas Gaharu (Aquilaria Malaccensis Lamk)

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    The benefits of Aquilaria malaccensis cause many people do the illegal activities to collect Aquilaria. Illegal logging causes Aquilaria in the endangered category species so that the export trade of this plant is limited. The problem of propagation of aquilaria can be solve with tissue culture techniques. The research objective is to determine the influencce of Naphthalene acetic acid (NAA) and Benzyl amino purine (BAP) on the development of subcultures best aloes. The research was conducted at the Laboratory of Silviculture Faculty of Forestry University Tanjungpura, observations made during six weeks. The method used in this study is factorial completely randomized design (CRD) in this study is factorial completely randomized design (CRD) with, Data were analyzed with analysis of variance and followed HSD test. such as ; NAA and BAP as factors with three concentration level and six replicant, as follows NAA (A) : 0.1 mg/l ; 0.15 mg/l ; 0.2 mg/l and BAP (B) : 2.5 mg/l ; 3.0 mg/l ; 3.5 mg/l). The results showed that the interaction between NAA and BAP concentrations has significantly influence to the development of Aquilaria subculture. In this study the best concentration is A1B1 (0.1 mg/l NAA and 2,5 mg/l BAP) where the number of shoots produced as many as 12 buds. Key words : Naphthalene acetic acid, Benzyl amino purine, Growth hormone, Subcultures and Aquilaria malaccensis

    Penilaian Daya Tarik dan Pengembangan Objek Wisata Pantai Tanjung Belandang di Kabupaten Ketapang

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    Tanjung Belandang beach is an area which have potential and attractiveness as a tourist attraction. Natural tourist attraction located in area Tanjung Belandang beach which supported with existence of infrastructure, accommodation, accessibility, and so should be improved development especially if viewed from aspects of tourism. The method used is survey method with descriptive and used interview techniques with instrument a questionnaire. Analysis of data using analysis of Regional Operations Guidelines and Nature Attractions Directorate General PHKA 2003 and SWOT Analysis. The result showed rating attraction tourism object Tanjung Belandang beach have value 491,22. After compared with the classification of business development of nature tourism, an area Tanjung Belandang beach have valuation medium (B). This means potential developed into a tourist attraction. Based on assessment for tourism development strategy Tanjung Belandang beach are in quadrant III (WO Strategy) is to maximize opportunities and minimize the threats that exist. As for the points for WO strategy namely: a. Increasing interest tourists to the marine tourism and need to improve the infrastructure supporting tourism facilities; b. Located close to the city center streets in tourist attraction areas need to be improved to provide comfort for visitors; c. Development of tourism as banana boat we need to prepare human resources capable to manage; d. Improve the facilities and infrastructure to support marine tourism; e. Need the support of local government in the development of marine tourism; f. Regional government must make policies to improve facilities and infrastructure so as to attract investor to invest. Keywords: Tourist attraction, nature tourism, beach, Tanjung Belandan

    Multiple exciton generation in nano-crystals revisited: Consistent calculation of the yield based on pump-probe spectroscopy

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    Multiple exciton generation (MEG) is a process in which more than one exciton is generated upon the absorption of a high energy photon, typically higher than two times the band gap, in semiconductor nanocrystals. It can be observed experimentally using time resolved spectroscopy such as the transient absorption measurements. Quantification of the MEG yield is usu- ally done by assuming that the bi-exciton signal is twice the signal from a single exciton. Herein we show that this assumption is not always justified and may lead to significant errors in the estimated MEG yields. We develop a methodology to determine proper scaling factors to the signals from the transient absorption experiments. Using the methodology we find modest MEG yields in lead chalcogenide nanocrystals including the nanorods

    Deep-water macroalgae from the Canary Islands: new records and biogeographical relationships

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    Due to the geographical location and paleobiogeography of the Canary Islands, the seaweed flora contains macroalgae with different distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae recently collected around the Canarian archipelago are discussed. These are Bryopsidella neglecta (Berthotd) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck, Hincksia onslowensis (Amsler et Kapraun)P.C. Silva, Syringoderma floridana Henry, Peyssonnelia harveyana J. Agardh, Cryptonemia seminervis(C. Agardh) J. Agardh, Botryodadia wynnei Ballantine, Gloiocladia blomquistii (Searles) R. E.Norris, PIahchrysis peltata (W. R. Taylor) P. Huv4 et H. Huv4, Leptofauchea brasiliensis Joly, and Sarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae,support the strong affinity of the Canary Islands seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western Atlantic regions

    The African hind's (Cephalopholis taeniops, serranidae) use of artificial reefs off Sal Island (Cape Verde): a preliminary study based on acoustic telemetry

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    The African hind Cephalopholis taeniops (Valenciennes, 1828) is one of the most important commercial demersal species caught in the Cape Verde archipelago. The species is closely associated with hard substrate and is one of the main attractions for SCUBA divers. In January 2006 a former Soviet fishing vessel - the Kwarcit - was sunk off Santa Maria Bay (Sal Island). Young C. taeniops are commonly observed in this artificial reef (AR). In order to investigate the species' use of the AR, 4 specimens were captured and surgically implanted underwater with Vemco brand acoustic transmitters. The fish were monitored daily with an active telemetry receiver for one week after release. Simultaneously, an array of 3 passive VR2 / VR2W receivers was set for 63 days, registering data that allowed an analysis of spatial, daily and short term temporal activity patterns. The results showed site fidelity to the AR, with no migrations to the nearby natural reef. The method used allowed to register a consistent higher activity during daytime and a preference for the area opposite the dominant current
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