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Sample records for dose-sensitive optically stimulated

  1. Optically stimulated luminesence dosimeter

    International Nuclear Information System (INIS)

    Liu Qiujiang; Zhu Lei; Zhu Lei; Chinese Academy of Sciences, Beijing; Chen Zhaoyang; Fan Yanwei; Ba Weizhen; Cong Xiuyun; Tang Xinqiang; Guo Qi; Lu Wu

    2007-01-01

    In this paper, the principle and makeup of optically stimulated luminescence dosimeter is described, and a measurement for radiation is carried, some actual problem is discussed. The dosimeter has high sensitive and can be reseted in-flight by stimulated light. (authors)

  2. Optically stimulated luminescence

    International Nuclear Information System (INIS)

    Espinosa, G.; Bogard, J.S.

    2007-01-01

    Full text: The use of Optically Stimulated Luminescence (OSL) for radiation dosimetry has become increasingly popular in recent years. The OSL method is based on luminescence emitted from semiconductor materials stimulated with specific wavelengths of light, after being exposed to ionizing radiation. The OSL intensity is a function of the radiation dose absorbed by the material. This work complements previous studies by the authors of the thermoluminescence (TL) response by SiO 2 commercial optical fiber exposed to ionizing radiation and provides preliminary results describing some of the material's OSL properties. Linear OSL response to beta radiation dose, along with a consistent shape of the photon emission curve with time, were observed using a green/blue OSL excitation laser. The reproducibility of OSL response after repeated irradiations and the change in intensity with time were also examined. The search and characterization of materials that exhibit this OSL response, in parallel with the continued development of OSL methodology and instrumentation, is an important scientific and commercial issue. (Author)

  3. Optical stimulated luminescence (OSL) dating

    International Nuclear Information System (INIS)

    Banerjee, D.

    1999-01-01

    Since the pioneering work by Huntley et al. (1985), optical dating is being increasingly recognised as an important technique for establishing a time frame of deposition of sediments (Aitken, 1998). Optical dating differs from thermoluminescence (TL) dating in that visible/infrared light from lasers or LEDs (light-emitting-diodes) is used as a means of stimulation, in contrast to thermal stimulation. It has several advantages over TL dating: (i) the resetting of the OSL (optically stimulated luminescence) clock is more effective than that of TL clock; for sediments transported under water or in other situations where the sediment grains have undergone inhomogeneous bleaching, this property ensures that ages based on optical dating are generally more reliable than TL ages, (ii) the optical dating technique is non-destructive, and multiple readouts of the optical signal is possible; this feature has resulted in the development of single-aliquot and single-grain protocols (Murray and Wintle, 1999; Banerjee et al. 1999), (iii) the sample is not heated as in TL; thus, spurious luminescence is avoided and there is a significant reduction in blackbody radiation. Dating of materials which change phase on heating is also practical, and finally, (iv) thermal quenching of luminescence is negligible, allowing accurate estimation of kinetic parameters using standard techniques and providing access to deep OSL traps. This characteristic may be helpful in extending the limits of optical dating beyond the last 150 ka from a global point of view

  4. Optical stimulator for vision-based sensors

    DEFF Research Database (Denmark)

    Rössler, Dirk; Pedersen, David Arge Klevang; Benn, Mathias

    2014-01-01

    stimulator is used as a test bench to simulate high-precision navigation by different types of camera systems that are used onboard spacecraft, planetary rovers, and for spacecraft rendezvous and proximity maneuvers. Careful hardware design and preoperational calibration of the stimulator result in high......We have developed an optical stimulator system for vision-based sensors. The stimulator is an efficient tool for stimulating a camera during on-ground testing with scenes representative of spacecraft flights. Such scenes include starry sky, planetary objects, and other spacecraft. The optical...... precision and long-term stability. The system can be continuously used over several days. By facilitating a full camera including optics in the loop, the stimulator enables the more realistic simulation of flight maneuvers based on navigation cameras than pure computer simulations or camera stimulations...

  5. Thermo-optical properties of optically stimulated luminescence in feldspars

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Johnsen, O.

    1995-01-01

    Optically stimulated luminescence processes in feldspars are subject to competing thermal enhancement and quenching processes: this article describes the thermal enhancement effects for orthoclase, albite and plagioclase feldspars. It is demonstrated that certain lattice vibrational modes can...

  6. Optically stimulated luminescence dating of rock surfaces

    DEFF Research Database (Denmark)

    Sohbati, Reza

    There are many examples of rock surfaces, rock art and stone structures whose ages are of great importance to the understanding of various phenomena in geology, climatology and archaeology. Optically stimulated luminescence (OSL) dating is a well-established chronological tool that has successful...

  7. Optically stimulated luminescence dating of young sediments

    DEFF Research Database (Denmark)

    Madsen, Anni Tindahl; Murray, Andrew S.

    2009-01-01

    Optically stimulated luminescence (OSL) dating of young (... of OSL dating, outlines the problems specific to the dating of young material, and then uses recent applications to young sediments to illustrate the greatly increased scope and potential of the method in geomorphology and the geology of recent deposits. The overall reliability of this new generation...

  8. Optically Stimulated Luminescence Fundamentals and Applications

    CERN Document Server

    McKeever, Stephen

    2011-01-01

    The book discusses advanced modern applications of optically stimulated luminescence including the appropriate fundamentals of the process. It features major chapters on the use of OSL in space radiation dosimetry, medical physics, personnel dosimetry, security, solid-state physics and other related applications. In each case, the underlying theory is discussed on an as-needed basis for a complete understanding of the phenomena, but with an emphasis of the practical applications of the technique. After an introductory chapter, Chapters 2 to 6 cover basic theory and practical aspects, personal

  9. Luminescence optically stimulated: theory and applications

    International Nuclear Information System (INIS)

    Rivera M, T.; Azorin N, J.

    2002-01-01

    The thermally stimulated luminescence (Tl) has occupied an important place in the Solid state physics (FES) by the flexibility of the phenomena, mainly for its applications in the fields of Radiation Physics (FR) and Medical Physics (MF). The reason of this phenomena lies in the fact of the electrons release by the action of heat. Under that same reason, it can be used the action of another stimulant agent for releasing the trapped electrons in the metastable states (EM), this agent is the light which has the same effect that the heat, giving as result the production of light photons at using light in the visible spectra, of different wavelength that the excitation light. This phenomena is called Luminescence optically stimulated (LOE). The LOE has a great impact in the Solid State Physics (FES), dating and now in the use of the phenomena as a dosimetric method, alternate to the Tl, for its use in the ionizing and non-ionizing radiations fields. (Author)

  10. Plasmon-enhanced optically stimulated luminescence

    International Nuclear Information System (INIS)

    Guidelli, E. J.; Baffa, O.; Ramos, A. P.

    2015-10-01

    Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

  11. Plasmon-enhanced optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, E. J.; Baffa, O. [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Fisica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Ramos, A. P., E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Quimica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2015-10-15

    Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

  12. Simulation of optically-stimulated luminescence of zircon

    NARCIS (Netherlands)

    Turkin, A A; Vainshtein, D.I.; Hartog, H.W. den

    2007-01-01

    Mineral zircon, ZrSiO4, belongs to a class of materials that can be used as a chronological tool in geology and archaeology for measurements of the natural radiation dose and the sample age by optical methods. The model of optically stimulated luminescence developed earlier is used to investigate

  13. Time-gated optical imaging through turbid media using stimulated ...

    Indian Academy of Sciences (India)

    In this paper, we report the development of experimental set-up for timegated optical imaging through turbid media using stimulated Raman scattering. Our studies on the contrast of time-gated images show that for a given optical thickness, the image contrast is better for sample with lower scattering coefficient and higher ...

  14. In-homogeneity in the pre-dose sensitization of the 110 Degree-Sign C TL peak in various quartz samples: The influence of annealing

    Energy Technology Data Exchange (ETDEWEB)

    Polymeris, George S., E-mail: polymers@auth.gr [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, Cultural and Educational Technology Institute, Athena, Research and Innovation Center in Information, Communication and Knowledge Technologies, Tsimiski 58, GR-67100 Xanthi (Greece); ISIK University, Faculty of Science and Arts, Physics Department, Sile 34980, Istanbul (Turkey); Oniya, Ebenezer O. [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, Cultural and Educational Technology Institute, Athena, Research and Innovation Center in Information, Communication and Knowledge Technologies, Tsimiski 58, GR-67100 Xanthi (Greece); Physics and Electronics Department, Adekunle Ajasin University, PMB 01 Akungba Akoko (Nigeria); Jibiri, Nnamdi N. [Department of Physics, University of Ibadan, Ibadan (Nigeria); Tsirliganis, Nestor C. [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, Cultural and Educational Technology Institute, Athena, Research and Innovation Center in Information, Communication and Knowledge Technologies, Tsimiski 58, GR-67100 Xanthi (Greece); Kitis, George [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124 Thessaloniki (Greece)

    2012-03-01

    The pre-dose sensitization effect of the 110 Degree-Sign C TL glow-peak of quartz is a basic tool in thermoluminescence and optically stimulated luminescence dating and retrospective dosimetry. In the present work, a homogeneity study was performed on pre-dose sensitization in grains obtained from large quartz crystals samples collected from 10 different origins. The aliquot - to - aliquot scatter of the pre-dose sensitization of the 110 Degree-Sign C TL peak within each quartz crystal was monitored. The influence of the annealing on this scattering was also studied. Therefore, the investigation was applied to the un-fired 'as is' samples as well as to samples annealed at 900 Degree-Sign C for 1 h following cooling to room temperature in air. The results showed that in the case of 'as is' quartz the sensitization effect vary strongly within each aliquot of the same quartz sample. This strong variation is removed by both the high temperature annealing as well as heating up to 500 Degree-Sign C, involved in the TL measurements. These results are generally discussed in the framework of existing models and applications of the effect.

  15. Optically stimulated luminescence techniques in retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Murray, A.S.

    2001-01-01

    windows, and detection sensitivity, (ii) experience with various stimulation light sources, including filtered incandescent lamps (420-550 nm) and high intensity light emitting diodes (470 nm) and laser diodes (830-850 nm). We also discuss recently developed high-precision single-aliquot measurement...

  16. Implantable optical-electrode device for stimulation of spinal motoneurons

    International Nuclear Information System (INIS)

    Matveev, M V; Erofeev, A I; Zakharova, O A; Vlasova, O L; Pyatyshev, E N; Kazakin, A N

    2016-01-01

    Recent years, optogenetic method of scientific research has proved its effectiveness in the nerve cell stimulation tasks. In our article we demonstrate an implanted device for the spinal optogenetic motoneurons activation. This work is carried out in the Laboratory of Molecular Neurodegeneration of the Peter the Great St. Petersburg Polytechnic University, together with Nano and Microsystem Technology Laboratory. The work of the developed device is based on the principle of combining fiber optic light stimulation of genetically modified cells with the microelectrode multichannel recording of neurons biopotentials. The paper presents a part of the electrode implant manufacturing technique, combined with the optical waveguide of ThorLabs (USA). (paper)

  17. Optically stimulated luminescence dosimetry with gypsum wallboard (drywall).

    Science.gov (United States)

    Thompson, Jeroen W; Burdette, Kevin E; Inrig, Elizabeth L; Dewitt, Regina; Mistry, Rajesh; Rink, W Jack; Boreham, Douglas R

    2010-09-01

    Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d.

  18. Optically stimulated luminescence from quartz measured using the linear modulation technique

    DEFF Research Database (Denmark)

    Bulur, E.; Bøtter-Jensen, L.; Murray, A.S.

    2000-01-01

    The optically stimulated luminescence (OSL) from heated natural quartz has been investigated using the linear modulation technique (LMT), in which the excitation light intensity is increased linearly during stimulation. In contrast to conventional stimulation, which usually produces a monotonical...

  19. SBS [stimulated Brillouin scattering] pulse distortion in multimode optical fibers

    International Nuclear Information System (INIS)

    Smith, J.R.; Hawkins, R.J.; Laumann, C.W.; Hatch, J.

    1989-01-01

    We have observed sever temporal-pulse-shape distortion due to stimulated Brillouin scattering (SBS) in multimode optical fibers used to diagnose 351 m laser pulses on the Nova laser system. Our measurements can be fit by a basic model of SBS and provide a clear indication of the intensity and temporal regimes where significant SBS-induced temporal-pulse-shape distortion can be avoided. 15 refs., 3 figs., 1 tab

  20. EDITORIAL: Special issue on optical neural engineering: advances in optical stimulation technology Special issue on optical neural engineering: advances in optical stimulation technology

    Science.gov (United States)

    Shoham, Shy; Deisseroth, Karl

    2010-08-01

    Neural engineering, itself an 'emerging interdisciplinary research area' [1] has undergone a sea change over the past few years with the emergence of exciting new optical technologies for monitoring, stimulating, inhibiting and, more generally, modulating neural activity. To a large extent, this change is driven by the realization of the promise and complementary strengths that emerging photo-stimulation tools offer to add to the neural engineer's toolbox, which has been almost exclusively based on electrical stimulation technologies. Notably, photo-stimulation is non-contact, can in some cases be genetically targeted to specific cell populations, can achieve high spatial specificity (cellular or even sub-cellular) in two or three dimensions, and opens up the possibility of large-scale spatial-temporal patterned stimulation. It also offers a seamless solution to the problem of cross-talk generated by simultaneous electrical stimulation and recording. As in other biomedical optics phenomena [2], photo-stimulation includes multiple possible modes of interaction between light and the target neurons, including a variety of photo-physical and photo-bio-chemical effects with various intrinsic components or exogenous 'sensitizers' which can be loaded into the tissue or genetically expressed. Early isolated reports of neural excitation with light date back to the late 19th century [3] and to Arvanitaki and Chalazonitis' work five decades ago [4]; however, the mechanism by which these and other direct photo-stimulation, inhibition and modulation events [5-7] took place is yet unclear, as is their short- and long-term safety profile. Photo-chemical photolysis of covalently 'caged' neurotransmitters [8, 9] has been widely used in cellular neuroscience research for three decades, including for exciting or inhibiting neural activity, and for mapping neural circuits. Technological developments now allow neurotransmitters to be uncaged with exquisite spatial specificity (down to

  1. Dosimetry based on thermally and optically stimulated luminescence

    International Nuclear Information System (INIS)

    Agersnap Larsen, Niels

    1999-01-01

    Thermally Stimulated Luminescence (TL) and Optically Stimulated Luminescence (OSL) properties of quartz and α-Al 2 O 3 have been investigated. Anneling-induced OSL and TL sensitivity changes in quartz has been investigated by experiments and modelling. This study does not support a pre-dose effect to account for the observed annealing-induced sensitivity change. The experimental data indicates a more simple mechanism that involves alteration of the concentration of the defect centers. Results from modelling of removal or creation of defect centers comparing well with experimentally obtained data. Thermal quenching of luminescence for the main emission center, the F-center, in α-Al 2 O 3 :C has been investigated by analysing TL curves obtained at different heating rates. The thermal quenching dependence of luminescence is found to follow the classical Mott-Seitz expression. Basic investigations of OSL properties of αAl 2 O 3 :C, including: the thermal depth of the OSL traps, the temperature dependence of OSL, and the OSL stimulation spectra. Simultaneous measurements of TL and thermally stimulated conductivity (TSC) are presented for γ-irradiated αAl 2 O 3 :C. Activation energy analysis of the data reveals a superposition of several first-order TL and TSC peaks caused by release of charge carriers from a distribution of trapping states. Furthermore a description of an experimental method developed to determine the sign of the thermally released charge carriers has been presented. (au)

  2. Optically stimulated luminescence dosimetry using natural and synthetic materials

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; McKeever, S.W.S.

    1996-01-01

    The application of optically stimulated luminescence (OSL) for use in radiation dosimetry is reviewed. A broad description is given of OSL techniques developed at Riso National Laboratory and at Oklahoma State University, and recent collaborative investigations on the properties of a variety...... of natural and synthetic materials are reported. A phenomenological description of OSL is presented, and examples of recent applications are discussed. Some basic studies of OSL are described, from a variety of materials, including Al2O3:C, natural quartz and feldspars extracted from building materials...

  3. A programmable optical stimulator for the Drosophila eye

    Directory of Open Access Journals (Sweden)

    Xinping Chen

    2017-10-01

    Full Text Available A programmable optical stimulator for Drosophila eyes is presented. The target application of the stimulator is to induce retinal degeneration in fly photoreceptor cells by exposing them to light in a controlled manner. The goal of this work is to obtain a reproducible system for studying age-related changes in susceptibility to environmental ocular stress. The stimulator uses light emitting diodes and an embedded computer to control illuminance, color (blue or red and duration in two independent chambers. Further, the stimulator is equipped with per-chamber light and temperature sensors and a fan to monitor light intensity and to control temperature. An ON/OFF temperature control implemented on the embedded computer keeps the temperature from reaching levels that will induce the heat shock stress response in the flies. A custom enclosure was fabricated to house the electronic components of the stimulator. The enclosure provides a light-impermeable environment that allows air flow and lets users easily load and unload fly vials. Characterization results show that the fabricated stimulator can produce light at illuminances ranging from 0 to 16000 lux and power density levels from 0 to 7.2 mW/cm2 for blue light. For red light the maximum illuminance is 8000 lux which corresponds to a power density of 3.54 mW/cm2. The fans and the ON/OFF temperature control are able to keep the temperature inside the chambers below 28.17 °C. Experiments with white-eye male flies were performed to assess the ability of the fabricated simulator to induce blue light-dependent retinal degeneration. Retinal degeneration is observed in flies exposed to 8 h of blue light at 7949 lux. Flies in a control experiment with no light exposure show no retinal degeneration. Flies exposed to red light for the similar duration and light intensity (8 h and 7994 lux do not show retinal degeneration either. Hence, the fabricated stimulator can be used to create environmental

  4. Optically stimulated luminescence (OSL) study of synthetic stishovite

    International Nuclear Information System (INIS)

    Tani, A.; Yamanaka, C.; Ikeya, M.; Ohtaka, O.; Takada, M.; Katsura, T.

    2000-01-01

    Optically stimulated luminescence (OSL) of synthetic stishovite was investigated for a future dating technique of meteor impact craters. Luminescence around 330 nm was measured on the γ-ray irradiated stishovite under two stimulating light sources of infrared laser (830 nm) and blue light emitting diode set (470 nm). Thermoluminescence (TL) studies before and after the OSL measurements showed the intensities around 100-200 deg. C and 220-350 deg. C to increase and those around 350-450 deg. C to decrease. This indicates that a part of deep-trapped charges excited during the OSL measurements were retrapped by shallower traps. The infrared stimulated luminescence (IRSL) after the TL measurement up to 450 deg. C could not be detected, while the blue light stimulated luminescence (BLSL) after TL had about one-tenth of the intensity before TL. This indicates that a part of the charges in shallower traps were detrapped thermally and returned to the deeper traps which were related to BLSL. The result implies that some of the BLSL-related traps are quite stable at room temperature and could be used for geological dating. In addition, two paramagnetic centers produced by sudden release of high pressure in synthesis process were found in the unirradiated stishovite by electron spin resonance (ESR). Their g-factors are g parallel =2.00181 and g perpendicular =2.00062 for an axial signal and g=2.00305 for the other isotropic signal. These signals could be used for an evidence of impacts if those signals could be stored in geological time

  5. Aluminum Nitride Ceramic as an Optically Stimulable Luminescence Dosimeter Plate

    Directory of Open Access Journals (Sweden)

    Go Okada

    2016-04-01

    Full Text Available Photostimulable storage phosphors have been used in a wide range of applications including radiation measurements in one- and two-dimensional spaces, called point dosimetry and radiography. In this work, we report that an aluminum nitride (AlN ceramic plate, which is practically used as a heat sink (SHAPAL®, Tokuyama Corp., Yamaguchi, Japan, shows good optically-stimulated luminescence (OSL properties with sufficiently large signal and capability for imaging applications, and we have characterized the AlN plate for OSL applications. Upon interaction with X-rays, the sample color turns yellowish, due to a radiation-induced photoabsorption band in the UV-blue range below ~500 nm. After irradiating the sample with X-rays, an intense OSL emission can be observed in the UV (360 nm spectral region during stimulation by red light. Although our measurement setup is not optimized, dose detection was confirmed as low as ~3 mGy to over 20 Gy. Furthermore, we have successfully demonstrated that the SHAPAL® AlN ceramic plate has great potential to be used as an imaging plate in radiography.

  6. Modelling of optically stimulated luminescence of zircon : assessment of the suitability for dating

    NARCIS (Netherlands)

    Turkin, A.A.; Vainshtein, D.I.; Hartog, H.W. den

    2006-01-01

    The mineral zircon, ZrSiO4, is a candidate material for optical dating because it exhibits luminescence after exposure to natural radioactivity. The kinetic model of zircon thermally stimulated luminescence proposed before has been modified and used to investigate optically Stimulated luminescence

  7. Detection of herbs and spices irradiated through optically stimulated luminescence

    International Nuclear Information System (INIS)

    Preciado, S.; Agundez A, Z.; Barboza F, M.; Cruz Z, E.

    2003-01-01

    The irradiation of foods is one of the common practices in several countries of the American and European continents. In spite of the widespread use of irradiation methods and technics of nutritious products, it doesn't exist a method of general use at the present time for the detection of previously submitted foods to irradiation with pasteurization ends or sterilization. In the present work the results are presented obtained in the detection of herbs and spices exposed to radiation in the range of 0.1 - 3 KGy, by means of the photostimulation with light of 470 nm. It was used for it a RIS0 model team TL/OSL-GIVE-15 conditioned with a β ray source, 90 Sr/ 90 Y and a source of light of 50 mW/cm2. samples of chili guajillo were studied, pepper, cumin, mint and camomile; achieving you to detect exhibitions of the order of 8.33x10 -4 KGy that which is indicative of the high sensitivity of the luminescence technique optically stimulated. The answer of the samples with regard to the radiation dose presents a range of lineality for low dose of the order of 0.5 KGy; and supralineal for further dose without to arrive to a saturation stage. (Author)

  8. Optically stimulated luminescence in electronic components for emergency dosimetry

    International Nuclear Information System (INIS)

    Geber-Bergstrand, T.; Bernhardsson, C.; Mattsson, S.; Raeaef, C.L.

    2015-01-01

    Document available in abstract form only. Full text of publication follows: Accidents and, luckily more rarely, attacks involving nuclear or radiological material do occur from time to time. A very possible consequence of an accident or attack of this kind is that nearby people might be exposed to ionising radiation. Since these types of exposure situations, unlike the ones occurring in medicine, are unplanned, there are no radiation-monitoring data available. For several reasons, it is nevertheless of value to find out the dose that these people have received. The first and most urgent reason is after-the-event triage, to be able to carry out proper medical treatments and also to focus the available medical assets to the persons needing it the most. This is where different retrospective dosimetry techniques, such as luminescence, can be employed. Various electronic components from mobile phones and other portable devices have been studied using optically stimulated luminescence for their potential use in retrospective dosimetry. Previous investigations have been performed in laboratory conditions and have showed very promising properties for emergency dosimetry. In this study, the more practical parts of using electronic components in retrospective dosimetry have been considered. In a triage situation, one of the key parameters to consider is time; thus, effort has been made to speed up the readout procedure, yet without the loss of too much accuracy. (authors)

  9. Time-gated optical imaging through turbid media using stimulated ...

    Indian Academy of Sciences (India)

    millimeter resolution imaging without the need for ionizing radiation and associated risks [1,2]. The fundamental problem with optical imaging is that in contrast to ... intensity dependent non-linear optical gates such as the optical Kerr effect [6], dye- based optical amplifier [7] etc. Duncan et al [8] and Mahon et al [9] exploited ...

  10. Bandwidth-tunable narrowband rectangular optical filter based on stimulated Brillouin scattering in optical fiber.

    Science.gov (United States)

    Wei, Wei; Yi, Lilin; Jaouën, Yves; Hu, Weisheng

    2014-09-22

    We propose a rectangular optical filter based on stimulated Brillouin scattering (SBS) in optical fiber with bandwidth tuning from 50 MHz to 4 GHz at less than 15-MHz resolution. The rectangular shape of the filter is precisely achieved utilizing digital feedback control of the comb-like pump spectral lines. The passband ripple is suppressed to ~1 dB by mitigating the nonlinearity influences of the comb-like pump lines generated in electrical and optical components and fibers. Moreover a fiber with a single Brillouin peak is employed to further reduce the in-band ripple and the out-of-band SBS gain at the same time. Finally, we analyze the noise performance of the filter at different bandwidth cases and demonstrate the system performance of the proposed filter with 2.1-GHz bandwidth and 19-dB gain by amplifying a 2-GHz orthogonal frequency-division-multiplexing (OFDM) signal with quadrature-phase-shift-keying (QPSK) and 16-quadrature-amplitude-modulation (16-QAM) on each subscriber.

  11. Saccade Modulation by Optical and Electrical Stimulation in the Macaque Frontal Eye Field

    Science.gov (United States)

    Grimaldi, Piercesare; Schweers, Nicole

    2013-01-01

    Recent studies have demonstrated that strong neural modulations can be evoked with optogenetic stimulation in macaque motor cortex without observing any evoked movements (Han et al., 2009, 2011; Diester et al., 2011). It remains unclear why such perturbations do not generate movements and if conditions exist under which they may evoke movements. In this study, we examine the effects of five optogenetic constructs in the macaque frontal eye field and use electrical microstimulation to assess whether optical perturbation of the local network leads to observable motor changes during optical, electrical, and combined stimulation. We report a significant increase in the probability of evoking saccadic eye movements when low current electrical stimulation is coupled to optical stimulation compared with when electrical stimulation is used alone. Experiments combining channelrhodopsin 2 (ChR2) and electrical stimulation with simultaneous fMRI revealed no discernible fMRI activity at the electrode tip with optical stimulation but strong activity with electrical stimulation. Our findings suggest that stimulation with current ChR2 optogenetic constructs generates subthreshold activity that contributes to the initiation of movements but, in most cases, is not sufficient to evoke a motor response. PMID:24133271

  12. Optically stimulated exoelectron emission processes in quartz: comparison of experiment and theory

    DEFF Research Database (Denmark)

    Pagonis, V.; Ankjærgaard, Christina; Murray, A.S.

    2009-01-01

    Recent experiments have demonstrated that it is possible to measure optically stimulated exoelectron emission (OSE) signals simultaneously with optically stimulated luminescence (OSL) from quartz samples. These experiments provide valuable information on the charge movement in quartz grains. Two ...... at W(0.29±0.02) eV. Good quantitative agreement is obtained between theory and experiment by assuming a thermal broadening of the thermal depletion factor for the OSL traps, described by a Gaussian distribution of energies....

  13. Optically Stimulated Luminescence Analysis Method for High Dose Rate Using an Optical Fiber Type Dosimeter

    Science.gov (United States)

    Ueno, Katsunori; Tominaga, Kazuo; Tadokoro, Takahiro; Ishizawa, Koji; Takahashi, Yoshinori; Kuwabara, Hitoshi

    2016-08-01

    The investigation of air dose rates at locations in the Fukushima Dai-ichi Nuclear Power Station is necessary for safe removal of the molten nuclear fuel. The target performance for the investigation is to analyze a dose rate in the range of 10-3 Gy/h to 102 Gy/h with a measurement precision of ±4.0% full scale (F.S.) at a measurement interval of 60 s. In order to achieve this target, the authors proposed an optically stimulated luminescence (OSL) analysis method using prompt OSL for a wide dynamic range of dose rates; the OSL is generated using BaFBr:Eu with a fast decay time constant. The luminescence intensity by prompt OSL was formulated by the electron concentration of the trapping state during gamma ray and stimulation light irradiations. The prototype OSL monitor using BaFBr:Eu was manufactured for investigation of prompt OSL and evaluation of the measurement precision. The time dependence of the luminescence intensity by prompt OSL was analyzed by irradiating the OSL sensor in a 60Co irradiation facility. The measured dose rates were obtained in a prompt mode and an accumulating mode with a precision of ±3.3% F.S. for the dose rate range of 9.5 ×10-4 Gy/h to 1.2 ×102 Gy/h.

  14. Influence of crystal structure on the optically stimulated luminescence properties of feldspars

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Ypma, P.J.M.

    1994-01-01

    Work is presented showing that the crystal structure of feldspar plays an important role in determining the energy positions at which optically stimulated luminescence transitions can occur, their thermo-optical behavior, the transport properties of charge in the conduction and valence bands...

  15. Measurement of optically and thermally stimulated electron emission from natural minerals

    DEFF Research Database (Denmark)

    Ankjærgaard, C.; Murray, A.S.; Denby, P.M.

    2006-01-01

    to a Riso TL/OSL reader, enabling optically stimulated electrons (OSE) and thermally stimulated electrons (TSE) to be measured simultaneously with optically stimulated luminescence (OSL) and thermoluminescence (TL). Repeated irradiation and measurement is possible without removing the sample from...... the counting chamber. Using this equipment both OSE and TSE from loose sand-sized grains of natural minerals has been recorded. It is shown that both the surface electron traps (giving rise to the OSE signals) and the bulk traps (giving rise to OSL) have the same dosimetric properties. A comparison of OSL...

  16. Implantable optogenetic device with CMOS IC technology for simultaneous optical measurement and stimulation

    Science.gov (United States)

    Haruta, Makito; Kamiyama, Naoya; Nakajima, Shun; Motoyama, Mayumi; Kawahara, Mamiko; Ohta, Yasumi; Yamasaki, Atsushi; Takehara, Hiroaki; Noda, Toshihiko; Sasagawa, Kiyotaka; Ishikawa, Yasuyuki; Tokuda, Takashi; Hashimoto, Hitoshi; Ohta, Jun

    2017-05-01

    In this study, we have developed an implantable optogenetic device that can measure and stimulate neurons by an optical method based on CMOS IC technology. The device consist of a blue LED array for optically patterned stimulation, a CMOS image sensor for acquiring brain surface image, and eight green LEDs surrounding the CMOS image sensor for illumination. The blue LED array is placed on the CMOS image sensor. We implanted the device in the brain of a genetically modified mouse and successfully demonstrated the stimulation of neurons optically and simultaneously acquire intrinsic optical images of the brain surface using the image sensor. The integrated device can be used for simultaneously measuring and controlling neuronal activities in a living animal, which is important for the artificial control of brain functions.

  17. Blue light emitting diodes for optical stimulation of quartz in retrospective dosimetry and dating

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Duller, G.A.T.; Murray, A.S.

    1999-01-01

    Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs...... (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination...... of the dependence of the blue LED OSL on preheat temperature, it is deduced that there is no evidence that the blue LEDs stimulate deep traps in a different manner from broadband filtered light. It is concluded that blue LEDs offer a practical alternative to existing stimulation sources. They have the significant...

  18. Scintillation and optical stimulated luminescence of Ce-doped CaF2

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Watanabe, Kenichi; Fukuda, Kentaro; Kawaguchi, Noriaki; Miyamoto, Yuka; Nanto, Hidehito

    2014-01-01

    Scintillation and optical stimulated luminescence of Ce 0.1–20% doped CaF 2 crystals prepared by Tokuyama Corp. were investigated. In X-ray induced scintillation spectra, luminescence due to Ce 3+ 5d–4f transition appeared around 320 nm with typically 40 ns decay time. By 241 Am 5.5 MeV α-ray irradiation, 0.1% doped one showed the highest scintillation light yield and the light yield monotonically decreased with Ce concentrations. Optically stimulated luminescence after X-ray irradiation was observed around 320 nm under 550 or 830 nm stimulation in all samples. As a result, intensities of optically stimulated luminescence were proportional to Ce concentrations. Consequently, scintillation and optically stimulated luminescence resulted to have a complementary relation in Ce-doped CaF 2 system. - Highlights: • Optical, scintillation, and OSL properties of Ce 0.1–20% doped CaF 2 were studied. • Scintillation light yield exhibited inverse proportionality to Ce concentrations. • OSL intensities showed proportionality to Ce concentrations. • Complementary relation of scintillation and OSL was experimentally confirmed

  19. Postural adaptations to repeated optic flow stimulation in older adults

    OpenAIRE

    O’Connor, Kathryn W.; Loughlin, Patrick J.; Redfern, Mark S.; Sparto, Patrick J.

    2008-01-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of ...

  20. Intrinsic optical imaging study on cortical responses to electrical stimulation in ventral posterior medial nucleus of thalamus.

    Science.gov (United States)

    Zhang, Jiacheng; Zhang, Shaomin; Yu, Chaonan; Zheng, Xiaoxiang; Xu, Kedi

    2018-04-01

    Intracortical electrical micro-stimulation has been applied widely for the attempts on reconstruction of sensory functions. More recently, thalamic electrical stimulation has been proposed as a promising target for somatosensory stimulation. However, the cortical activations and mechanisms evoked by VPM stimulation remained unclear. In this report, the cortical neural responses to electrical stimulations were recorded by optical imaging of intrinsic signals. The impact of stimulation parameters was characterized to illustrate how the VPM stimulation alter cortical activities. Significant increases were found in cortical responses with increased stimulation amplitude or pulse width. However, frequency modulation exhibited significant inhibition with higher frequency stimulation. Our results suggest that optical imaging of intrinsic signals is sensitive and reliable to deep brain stimulations. These results may not only help to understand the modulation effects through thalamocortical pathway, but also show the possibility to use VPM stimulation to evoke frequency-tuned tactile sensations in rats. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Optically stimulated luminescence dating at Rose Cottage Cave

    CSIR Research Space (South Africa)

    Pienaar, M

    2008-01-01

    Full Text Available measurements. Radiation Measurements 37, 161–165. 30. Jacobs Z., Wintle A.G. and Duller G.A.T. (2003). Optical dating of dune sand from Blombos Cave, South Africa: I – multiple grain data. J. Hum. Evol. 44, 599–612. 31. Jacobs Z., Wintle A.G. and Duller G...

  2. Further investigations into pulsed optically stimulated luminescence from feldspars using blue and green light

    International Nuclear Information System (INIS)

    Ankjaergaard, C.; Jain, M.; Kalchgruber, R.; Lapp, T.; Klein, D.; McKeever, S.W.S.; Murray, A.S.; Morthekai, P.

    2009-01-01

    The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time-resolved optically stimulated luminescence (TR-OSL), and these signals can be mathematically described as a sum of 4 exponential components (a, b, c, d). The slowest component, d, increases with the duration of the light pulse as expected from the exponential model. The stimulation temperature dependence experiment suggests that the TR-OSL signal decay is governed by the recombination process and not by the excited state lifetime. Furthermore data from the TR-OSL signal dependence on stimulation time and preheat temperature suggest that the recombination process may not be a sum of exponentials, although the model cannot be rejected definitively.

  3. Cortical potentials after electrical intraneural stimulation of the optic nerve during orbital enucleation.

    Science.gov (United States)

    Benedičič, Mitja; Beltram, Matej; Olup, Brigita Drnovšek; Bošnjak, Roman

    2012-12-01

    The aim of this study was to present cortical potentials after electrical intraneural stimulation of the optic nerve during orbital enucleation due to malignant melanoma of the choroid or the ciliary body. These cortical potentials were related to cortical potentials after electrical epidural stimulation of the optic nerve, recorded during non-manipulative phases of neurosurgery for central skull base tumors. Cortical potentials were recorded with surface occipital electrode (Oz) in six patients undergoing orbital enucleation under total intravenous anesthesia. Two thin needle stimulating electrodes were inserted inside the intraorbital part of the optic nerve. The electrical stimulus consisted of a rectangular current pulse of varying intensity (0.2-10.0 mA) and duration (0.1-0.3 ms); the stimulation rate was 2 Hz; the bandpass filter was 1-1,000 Hz; the analysis time was 50-300 ms. Cortical potentials could not be obtained or were inconsistently elicitable in three patients with longstanding history (>3 months) of severe visual deterioration, while they consisted of several positive and negative deflections in a patient with a short history of mild visual impairment. In two other patients, cortical potentials consisted of N20, P30 and N40 waves. Cortical potentials after electrical intraneural stimulation of the optic nerve could be recorded in patients with a short history of visual deterioration and without optic nerve atrophy and appear more heterogeneous than cortical potentials after electrical epidural stimulation of the optic nerve, recorded during non-manipulative phases of neurosurgery for central skull base tumors.

  4. Note: Automated optical focusing on encapsulated devices for scanning light stimulation systems

    International Nuclear Information System (INIS)

    Bitzer, L. A.; Benson, N.; Schmechel, R.

    2014-01-01

    Recently, a scanning light stimulation system with an automated, adaptive focus correction during the measurement was introduced. Here, its application on encapsulated devices is discussed. This includes the changes an encapsulating optical medium introduces to the focusing process as well as to the subsequent light stimulation measurement. Further, the focusing method is modified to compensate for the influence of refraction and to maintain a minimum beam diameter on the sample surface

  5. Note: Automated optical focusing on encapsulated devices for scanning light stimulation systems.

    Science.gov (United States)

    Bitzer, L A; Benson, N; Schmechel, R

    2014-08-01

    Recently, a scanning light stimulation system with an automated, adaptive focus correction during the measurement was introduced. Here, its application on encapsulated devices is discussed. This includes the changes an encapsulating optical medium introduces to the focusing process as well as to the subsequent light stimulation measurement. Further, the focusing method is modified to compensate for the influence of refraction and to maintain a minimum beam diameter on the sample surface.

  6. Determination of U, Th and K for optically stimulated luminescence dating by NAA

    International Nuclear Information System (INIS)

    Qin Yali; Chen Zhe; Wu Weiming

    2010-01-01

    Optically stimulated luminescence dating techniques have been widely used in northern Loess ancient soil series and recorded climate environment change, ancient earthquake, the ancients site and archaeology research. The determination of U, Th and K using neutron activation analysis (NAA) has been optimized for the samples related to OSL dating research. The procedure for determination of U, Th, K in loess have been fixed by using Miniature neutron source reactor. This procedure of NAA will provide a reliable data base for optically stimulated luminescence dating research. (authors)

  7. Influence of Stimuled Raman Scattering on Transmitted Optical Signal in WDM System

    Directory of Open Access Journals (Sweden)

    Ján Ružbarský

    2015-12-01

    Full Text Available Paper is focused on simulations behavior of signals in high-speed networks. Huge amount of transmitted information and increase in transmission speed create unwanted events in optical fiber. The main influences comprise effects such as: stimulated Raman scattering and stimulated Brillouin scattering. This paper is focused only on Raman scattering. For transmitting a signal through optical fiber one needs to select an appropriate wavelength. This is one of goals the experiment in this article. Signals were transmitted accordance with Dense Wavelength Division Multiplexing (DWDM and spacing among channels 100GHz.

  8. Postural adaptations to repeated optic flow stimulation in older adults

    Science.gov (United States)

    O’Connor, Kathryn W.; Loughlin, Patrick J.; Redfern, Mark S.; Sparto, Patrick J.

    2008-01-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of three conditions were performed: 1) constant 12 cm optic flow amplitude (24 cm peak-to-peak), 2) constant 4 cm amplitude (8 cm p-t-p), and 3) a transition in amplitude from 4 to 12 cm. The average power of head sway velocity (Pvel) was calculated for consecutive 5 s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the Pvel. Pvel was greater in older adults in all conditions (p Pvel of the older adults decreased significantly between all 3 trials, but decreased only between trial 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12 cm did not significantly change, older adults had an increase in Pvel following the transition, ranging from 6.5 dB for the first trial to 3.4 dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization. PMID:18329878

  9. An integrated optical coherence microscopy imaging and optical stimulation system for optogenetic pacing in Drosophila melanogaster (Conference Presentation)

    Science.gov (United States)

    Alex, Aneesh; Li, Airong; Men, Jing; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

    2016-03-01

    Electrical stimulation is the clinical standard for cardiac pacing. Although highly effective in controlling cardiac rhythm, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its applications. Optogenetic pacing of the heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids the shortcomings in electrical stimulation. Drosophila melanogaster, which is a powerful model organism with orthologs of nearly 75% of human disease genes, has not been studied for optogenetic pacing in the heart. Here, we developed a non-invasive integrated optical pacing and optical coherence microscopy (OCM) imaging system to control the heart rhythm of Drosophila at different developmental stages using light. The OCM system is capable of providing high imaging speed (130 frames/s) and ultrahigh imaging resolutions (1.5 μm and 3.9 μm for axial and transverse resolutions, respectively). A light-sensitive pacemaker was developed in Drosophila by specifically expressing the light-gated cation channel, channelrhodopsin-2 (ChR2) in transgenic Drosophila heart. We achieved non-invasive and specific optical control of the Drosophila heart rhythm throughout the fly's life cycle (larva, pupa, and adult) by stimulating the heart with 475 nm pulsed laser light. Heart response to stimulation pulses was monitored non-invasively with OCM. This integrated non-invasive optogenetic control and in vivo imaging technique provides a novel platform for performing research studies in developmental cardiology.

  10. Study of optically stimulated luminescence (OSL) for radiation detection. Application to an optical fibre γ-radiation sensor

    International Nuclear Information System (INIS)

    Roy, O.

    1998-01-01

    This work shows up the usefulness of the Optically Stimulated Luminescence (OSL) to resolve radioprotection problems. We study the use of OSL as a gamma dosimetric technique with respect to the ALARA's concept (As Low As Reasonably Achievable). A new approach based on optical fibers and luminescent materials showing OSL properties (closely related to Thermoluminescence phenomena) is presented in order to improve the remote real time dosimetry monitoring. Like thermoluminescent materials (TLD), OSL materials can trap charges under an irradiation (UV, X, γ,...). Instead of heating, the charges trapped are released by light stimulation and produce a visible luminescence which amount is proportional to trap the 'data stored' left by irradiation, enabling the dose measurement. The OSL phenomenon offers the same advantages as TLD plus the interesting possibility of a remote optical stimulation. The end-user objective deals with the development of a γ-radiation Optical FIber Sensor (OFS) for dose measurement which can offer new functionalities based on OSL materials coupled with an optical fiber. Rare earth doped Alkaline Earth Sulphides (AES), BAFX:EU 2+ (X = Cl, Br, I) and halogen alkaline have been studied (crystalline form, synthesis techniques, influence of dopants and color centers). Their characteristics are presented and extensively discussed. A specific experimental set-up to characterise various OSL phosphors has been developed. It allows the study of sensitivity, linearity, time decay behaviour of OSL signal and zeroing time. A joint study of OSL and TL has shown the technical limitations as well as the thermal fading and the origin of the long zeroing time. An Optical Fiber Sensor (OFS) based on OSL and using MgS:Sm has been developed for practical applications on nuclear fields. Its specifications are presented and discussed, moreover improvements are proposed. (author)

  11. Spatiotemporal changes of optical signals in the somatosensory cortex of neuropathic rats after electroacupuncture stimulation.

    Science.gov (United States)

    Cha, Myeounghoon; Chae, Younbyoung; Bai, Sun Joon; Lee, Bae Hwan

    2017-01-10

    Peripheral nerve injury causes physiological changes in primary afferent neurons. Neuropathic pain associated with peripheral nerve injuries may reflect changes in the excitability of the nervous system, including the spinothalamic tract. Current alternative medical research indicates that acupuncture stimulation has analgesic effects in various pain symptoms. However, activation changes in the somatosensory cortex of the brain by acupuncture stimulation remain poorly understood. The present study was conducted to monitor the changes in cortical excitability, using optical imaging with voltage-sensitive dye (VSD) in neuropathic rats after electroacupuncture (EA) stimulation. Male Sprague-Dawley rats were divided into three groups: control (intact), sham injury, and neuropathic pain rats. Under pentobarbital anesthesia, rats were subjected to nerve injury with tight ligation and incision of the tibial and sural nerves in the left hind paw. For optical imaging, the rats were re-anesthetized with urethane, and followed by craniotomy. The exposed primary somatosensory cortex (S1) was stained with VSD for one hour. Optical signals were recorded from the S1 cortex, before and after EA stimulation on Zusanli (ST36) and Yinlingquan (SP9). After peripheral stimulation, control and sham injury rats did not show significant signal changes in the S1 cortex. However, inflamed and amplified neural activities were observed in the S1 cortex of nerve-injured rats. Furthermore, the optical signals and region of activation in the S1 cortex were reduced substantially after EA stimulation, and recovered in a time-dependent manner. The peak fluorescence intensity was significantly reduced until 90 min after EA stimulation (Pre-EA: 0.25 ± 0.04 and Post-EA 0 min: 0.01 ± 0.01), and maximum activated area was also significantly attenuated until 60 min after EA stimulation (Pre-EA: 37.2 ± 1.79 and Post-EA 0 min: 0.01 ± 0.10). Our results indicate that EA stimulation

  12. Modelling the thermal quenching mechanism in quartz based on time-resolved optically stimulated luminescence

    DEFF Research Database (Denmark)

    Pagonis, V.; Ankjærgaard, Christina; Murray, Andrew

    2010-01-01

    This paper presents a new numerical model for thermal quenching in quartz, based on the previously suggested Mott–Seitz mechanism. In the model electrons from a dosimetric trap are raised by optical or thermal stimulation into the conduction band, followed by an electronic transition from the con...... experimental data obtained using a single-aliquot procedure on a sedimentary quartz sample....

  13. Probing metastable Sm2+ and optically stimulated tunnelling emission in YPO4: Ce, Sm

    DEFF Research Database (Denmark)

    Prasad, Amit Kumar; Kook, Myung Ho; Jain, Mayank

    2017-01-01

    optical stimulation. The work presented here adds further details to the energy levels of the metastable Sm2+ defect and the electron transfer processes by undertaking measurements of a) Sm2+ excitation spectrum through the internal 5D0 → 7F2 emission at 7 K, b) relaxation lifetime of Sm2+ (5D0 state...

  14. Surface exposure dating of non-terrestrial bodies using optically stimulated luminescence: A new method

    DEFF Research Database (Denmark)

    Sohbati, Reza; Jain, Mayank; Murray, Andrew

    2012-01-01

    We propose a new method for in situ surface exposure dating of non-terrestrial geomorphological features using optically stimulated luminescence (OSL); our approach is based on the progressive emptying of trapped charge with exposure to light at depth into a mineral surface. A complete model...

  15. Further investigations into pulsed optically stimulated luminescence from feldspars using blue and green light

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Kalchgruber, R.

    2009-01-01

    The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time-resolved opti......The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time...... suggests that the TR-OSL signal decay is governed by the recombination process and not by the excited state lifetime. Furthermore data from the TR-OSL signal dependence on stimulation time and preheat temperature suggest that the recombination process may not be a sum of exponentials, although the model...... cannot be rejected definitively....

  16. A study on the real-time radiation dosimetry measurement system based on optically stimulated luminescence

    International Nuclear Information System (INIS)

    Liu Yanping; Du Yanzhao; Chen Zhaoyang; Ba Weizhen; Fan Yanwei; Pan Shilie; Guo Qi

    2008-01-01

    The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions. (authors)

  17. Nonlinear optical absorption and stimulated Mie scattering in metallic nanoparticle suspensions.

    Science.gov (United States)

    He, Guang S; Law, Wing-Cheung; Baev, Alexander; Liu, Sha; Swihart, Mark T; Prasad, Paras N

    2013-01-14

    The nonlinear optical properties of four metallic (Au-, Au/Ag-, Ag-, and Pt-) nanoparticle suspensions in toluene have been studied in both femtosecond and nanosecond regimes. Nonlinear transmission measurements in the femtosecond laser regime revealed two-photon absorption (2PA) induced nonlinear attenuation, while in the nanosecond laser regime a stronger nonlinear attenuation is due to both 2PA and 2PA-induced excited-state absorption. In the nanosecond regime, at input pump laser intensities above a certain threshold value, a new type of stimulated (Mie) scattering has been observed. Being essentially different from all other well known molecular (Raman, Brillouin) stimulated scattering effects, the newly observed stimulated Mie scattering from the metallic nanoparticles exhibits the features of no frequency shift and low pump threshold requirement. A physical model of induced Bragg grating initiated by the backward Mie scattering from metallic nanoparticles is proposed to explain the gain mechanism of the observed stimulated scattering effect.

  18. Efficient trigger signal generation from wasted backward amplified stimulated emission at optical amplifiers for optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Kim Seung Taek

    2015-01-01

    Full Text Available This paper propose an optical structure to generate trigger signals for optical coherence tomography (OCT using backward light which is usually disposed. The backward light is called backward amplified stimulated emission generated from semiconductor optical amplifier (SOA when using swept wavelength tunable laser (SWTL. A circulator is applied to block undesirable lights in the SWTL instead of an isolator in common SWTL. The circulator also diverts backward amplified spontaneous lights, which finally bring out trigger signals for a high speed digitizer. The spectra of the forward lights at SOA and the waveform of the backward lights were measured to check the procedure of the trigger formation in the experiment. The results showed that the trigger signals from the proposed SWTL with the circulator was quite usable in OCT.

  19. Optical fibre dosemeter systems for clinical applications based on radioluminescence and optically stimulated luminescence from Al2O3:C

    DEFF Research Database (Denmark)

    Marckmann, C.J.; Andersen, C.E.; Aznar, M.C.

    2006-01-01

    for making ultra-small dosemeter probes that can easily be placed inside patients in radiation treatment. These probes have shown excellent properties in both head and neck intensity-modulated radiation therapy treatment and in mammography. The dose-response of the OSL signal for the new optical fibre......Optical fibre dosemeter systems based on radioluminescence and optically stimulated luminescence (OSL) from carbon-doped aluminium oxide (Al2O3:C) crystals were developed for in vivo real-time dose rate and absorbed dose measurements in radiotherapy and mammography. A technique was also developed...... dosemeter system showed a repeatability within 0.15% at a dose level of 60 mGy when integrated over 100 s. The temperature dependence in the range 0-45 degrees C showed a reproducibility within 1.3% when the OSL signal was integrated over 100 s....

  20. Biocompatible Optically Transparent MEMS for Micromechanical Stimulation and Multimodal Imaging of Living Cells.

    Science.gov (United States)

    Fior, Raffaella; Kwok, Jeanie; Malfatti, Francesca; Sbaizero, Orfeo; Lal, Ratnesh

    2015-08-01

    Cells and tissues in our body are continuously subjected to mechanical stress. Mechanical stimuli, such as tensile and contractile forces, and shear stress, elicit cellular responses, including gene and protein alterations that determine key behaviors, including proliferation, differentiation, migration, and adhesion. Several tools and techniques have been developed to study these mechanobiological phenomena, including micro-electro-mechanical systems (MEMS). MEMS provide a platform for nano-to-microscale mechanical stimulation of biological samples and quantitative analysis of their biomechanical responses. However, current devices are limited in their capability to perform single cell micromechanical stimulations as well as correlating their structural phenotype by imaging techniques simultaneously. In this study, a biocompatible and optically transparent MEMS for single cell mechanobiological studies is reported. A silicon nitride microfabricated device is designed to perform uniaxial tensile deformation of single cells and tissue. Optical transparency and open architecture of the device allows coupling of the MEMS to structural and biophysical assays, including optical microscopy techniques and atomic force microscopy (AFM). We demonstrate the design, fabrication, testing, biocompatibility and multimodal imaging with optical and AFM techniques, providing a proof-of-concept for a multimodal MEMS. The integrated multimodal system would allow simultaneous controlled mechanical stimulation of single cells and correlate cellular response.

  1. Optical parametric amplification and oscillation assisted by low-frequency stimulated emission.

    Science.gov (United States)

    Longhi, Stefano

    2016-04-15

    Optical parametric amplification and oscillation provide powerful tools for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency down-conversion process and, thus, it cannot be realized for signal waves at a frequency ω3 higher than the frequency of the pump wave ω1. In this Letter, we suggest a route toward the realization of upconversion optical parametric amplification and oscillation, i.e., amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of upconversion optical parametric oscillation at λ3=465 nm are given for a periodically poled lithium-niobate (PPLN) crystal doped with Nd(3+) ions.

  2. Optically stimulated luminescence of natural NaCl mineral from Dead Sea exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Pina L, Y. I. [UNAM, Facultad de Ciencias, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Marcazzo, J., E-mail: jesus.roman@nucleares.unam.mx [Instituto de Fisica Arroyo Seco - UNICEN, Pinto 399, 7000 Tandil (Argentina)

    2016-10-15

    Luminescence properties such as radioluminescence, thermoluminescence and optically stimulated luminescence have been studied on natural sodium chloride (NaCl) for dosimetric purposes in retrospective dosimetry (Timar-Gabor et al., 2013; Druzhyna et al., 2016). In this work, the optically stimulated luminescence (Cw-OSL) emissions of natural salt minerals, collected from Dead Sea in summer of 2015, were studied. The Cw-OSL dose response of natural salt was analyzed in the range between 0.2 and 10 Gy gamma dose of {sup 60}Co. Samples exposed at 3 Gy exhibited good repeatability with a variation coefficient of 4.6%. The thermal stability of the Cw-OSL response was analyzed to different temperatures from 50 up to 250 degrees Celsius using a heating rate of 5 degrees Celsius. The results showed that the natural Dead Sea salt minerals could be applied as natural dosimeter of gamma radiation. (Author)

  3. Reproducibility assessment of commercial optically stimulated luminescence system in diagnostic X-ray beams

    International Nuclear Information System (INIS)

    Yahaya Musa; Bradley, D.A.; Sunway University, Selangor; Karim, M.K.A.; Asmaliza Hashim

    2017-01-01

    This study investigates the reproducibility of commercial optically stimulated luminescence (OSL) system at different X-ray beams in general radiography. The reader stability was evaluated at first and found to be within the accepted tolerance level of ± 10%. Henceforth, reproducibility of OSL dosimeters due to repeated readouts after single exposure were found to be between 1.0% (80 kV/20 mGy) and 5.9% (80 kV/10 mAs), while reproducibility in repeated irradiation of optically stimulated luminescence dosimeters (OSLDs) from the same batch (80 kV/8 mGy) was between 1.8 and 4.3%. After multiple readouts of OSLD, the OSL signal decreased by approximately - 0.4% per readout and - 5.4% per 10 sequential readouts. The reproducibility response demonstrates the suitability of the nanoDots OSLD for use in radiography. (author)

  4. Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina

    to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical...... stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration...... an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling through the shallow traps. The results from feldspars show the relative roles of an IR excited state (IR resonance), band tails...

  5. Using optically stimulated electrons from quartz for the estimation of natural doses

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Murray, A.S.; Denby, Phil M.

    2009-01-01

    A flow-through Geiger-Müller pancake electron detector attachment has been fitted to a standard Risø TL/OSL reader enabling optically stimulated electrons (OSE) to be measured simultaneously with optically stimulated luminescence (OSL). Using this detector, OSE and OSL measurements from natural......, a dose recovery test shows that OSE can successfully recover a laboratory dose of 300 Gy given before any laboratory thermal treatment, for preheating temperatures between 160 and 260 °C. Furthermore, for the first time natural OSE decay curves are detected and these signals are used to estimate a burial...... dose using the single-aliquot regenerative-dose (SAR) procedure. Finally, a comparative study of the equivalent doses estimated using both OSE and OSL from 10 quartz samples are presented, and it is shown that OSE has a significant potential in retrospective dosimetry....

  6. Optically stimulated luminescence of natural NaCl mineral from Dead Sea exposed to gamma radiation

    International Nuclear Information System (INIS)

    Roman L, J.; Cruz Z, E.; Pina L, Y. I.; Marcazzo, J.

    2016-10-01

    Luminescence properties such as radioluminescence, thermoluminescence and optically stimulated luminescence have been studied on natural sodium chloride (NaCl) for dosimetric purposes in retrospective dosimetry (Timar-Gabor et al., 2013; Druzhyna et al., 2016). In this work, the optically stimulated luminescence (Cw-OSL) emissions of natural salt minerals, collected from Dead Sea in summer of 2015, were studied. The Cw-OSL dose response of natural salt was analyzed in the range between 0.2 and 10 Gy gamma dose of 60 Co. Samples exposed at 3 Gy exhibited good repeatability with a variation coefficient of 4.6%. The thermal stability of the Cw-OSL response was analyzed to different temperatures from 50 up to 250 degrees Celsius using a heating rate of 5 degrees Celsius. The results showed that the natural Dead Sea salt minerals could be applied as natural dosimeter of gamma radiation. (Author)

  7. Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ankjaergaard, C.

    2010-02-15

    Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

  8. The potential of optically stimulated luminescence for medieval building; A case study at Termez, Uzbekistan

    International Nuclear Information System (INIS)

    Vieillevigne, Emmanuelle; Guibert, Pierre; Rita Zuccarello, Agnese; Bechtel, Francoise

    2006-01-01

    Luminescence techniques thermoluminescence (TL) and optically stimulated luminescence (OSL) are generally used to assess the chronology of the last firing of ceramics. In the field of building archaeology, fired bricks can be dated by these techniques. Nevertheless, these luminescence ages are not exactly related to the construction of the building itself, but to the production of the building materials. In some cases, re-use is possible and this raises problems with the interpretation of the dating results. This led us to employ optically stimulated luminescence in a less conventional way. Before bricks were sealed in masonry by mortar, they would have been exposed to day light, and, as a result, the optical traps of the crystals on the material surface should have been bleached (zeroed by light). Dating the end of the bleaching period is possible by OSL using blue light for stimulation and by IRSL (infrared stimulated luminescence) using IR stimulation. Thus the OSL or IRSL age for these crystals is directly related to the construction of the architectural structure. Experiments were carried out to determine the suitability of this approach and to solve practical problems of sampling. The results show that the bleaching light penetrates between 0.5 to 1 mm into the bricks, according to their transparency. This depth is sufficient to collect enough quartz and feldspar inclusions that have been affected by light in the past, and thus date the construction of the masonry directly. Attempts at surface dating of bricks collected at the medieval citadel of Termez, Uzbekistan, already dated by TL, were the starting point of this research

  9. Developments in optically stimulated luminescence techniques for dating and retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Murray, A.S.

    1999-01-01

    Optically stimulated luminescence signals from natural quartz and feldspar are now used routinely in dating geological and archaeological materials. More recently they have also been employed in accident dosimetry, i.e. the retrospective assessment of doses received as a result of a nuclear accid......-precision single-aliquot measurement protocols. These offer exciting possibilities in dating and accident dosimetry, and are already leading to new demands on measurement techniques and facilities....

  10. Optically stimulated luminescence (OSL) as a chronometer for surface exposure dating

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew S.; Chapot, Melissa S.

    2012-01-01

    We pioneer a technique of surface-exposure dating based upon the characteristic form of an optically stimulated luminescence (OSL) bleaching profile beneath a rock surface; this evolves as a function of depth and time. As a field illustration of this new method, the maximum age of a premier examp......, at decadal to millennial timescales or perhaps longer (depending on the environmental dose rate) even for material subsequently buried. This has considerable potential in many archeological, geological and geo-hazard applications....

  11. Retrospective radiation dose reconstruction using optically stimulated luminescence on natural materials

    International Nuclear Information System (INIS)

    Boetter-Jensen, L.

    2000-01-01

    Optically stimulated luminescence (OSL) techniques especially aimed at using natural materials for retrospective reconstruction of accidental radiation doses in populated areas were developed and studied at Risoe as part of an EU research project. Quartz and feldspars separated from building materials, such as bricks and tiles, in addition to porcelain from toilet tanks had their OSL signals measured using different light sources for stimulation to assess radiation doses received by the material. Radiation doses were also evaluated from OSL measured directly on unseparated samples i.e. directly from the surface of brick and tile materials. The lower detection level for e.g. quartz extracted from a modem brick measured using a green light wavelength band as the stimulation light source was found to be less than 1 mGy. The techniques developed and applied are described and results from measurements carried out on a variety of materials are presented. (author)

  12. Thermoluminescence, luminescence optically stimulated and creation of defects in alkaline halogenides contaminated with Europium

    International Nuclear Information System (INIS)

    Barboza F, M.

    1999-01-01

    The alkaline halogenides have been subject matter of investigations related with the search of sensor materials for X-ray bidimensional images or optical memories. The understanding of the damage formation processes generated by ionizing and non-ionizing radiations is important for the correct design of devices that working as detectors and dosemeters of both type of radiations. In this work we present the investigation results related with the defects produced by the ionizing radiation type X and ultraviolet light in the range of 200-360 nm in crystals of KCl: Eu 2+ and KBr:Eu 2+ . It is examined the thermoluminescence and luminescence spectra with the purpose of identifying the exciton processes, owing to the excitation of the halogenide ions in which the primary defects correspond to the F and H centers. It has been found that the 400-600 nm emission is associated with the luminescence type that in his turn can be associated with autotrapped excitons perturbed by the impurity. On the other hand, it is examined the emission spectra of the luminescence optically stimulated in crystals of KBr: Eu 2+ and KCl: Eu 2+ finding too that such materials would be used as optical memories susceptible of to store information, and through of photostimulation to read this. It was determined that the F centers participate in the luminescence optically stimulated in these crystals, as well as too in the recombination processes responsible by the thermoluminescent emission. (Author)

  13. Comparison of the properties of various optically stimulated luminescence signals from potassium feldspar

    International Nuclear Information System (INIS)

    Fu Xiao; Zhang Jiafu; Zhou Liping

    2012-01-01

    Various optically stimulated luminescence signals from K-feldspar have been used to determine the equivalent doses of sediment samples. Understanding the properties of these optical signals is critical to evaluate their applicability and limitations to optical dating. In this paper, some properties of IRSL, post-IR OSL and post-IR IRSL signals (detected in the UV region using U-340 filters) from a museum sample of K-feldspar were investigated by analyzing the relationships between optical and TL signals, and the effect of optical bleaching and heating on optical signals. The trap parameters of the different optical signals were calculated using the pulse annealing method. The results show that this sample exhibits two regenerated TL peaks at ∼140 and ∼330 °C. Corresponding to the low temperature TL peak, the OSL and post-IR OSL signals appear to be more associated with lower temperature TL than the IRSL signal measured at 50 °C. Corresponding to the high temperature TL peak, the post-IR IRSL signals mainly originate from the more thermally stable traps associated with the high temperature TL, compared with the IRSL and post-IR OSL signals. However, the post-IR IRSL 225°C signal is shown to be hard to be bleached by blue light and simulated sunlight, compared with the IRSL 50°C and low temperature post-IR IRSL signals. The implication for optical dating is that the elevated temperature post-IR IRSL signals can be preferentially applied over other signals from K-feldspar, but it is desirable that the effectiveness of the pre-depositional zeroing of these signals is assessed.

  14. Reproducibility of optically stimulated luminescence measurements from single grains of Al2O3: C and annealed quartz

    DEFF Research Database (Denmark)

    Truscott, A.J.; Duller, G.A.T.; Bøtter-Jensen, L.

    2000-01-01

    We have measured some aspects concerning the performance of a new instrument for the measurement of optically stimulated luminescence (OSL) from single sand-sized grains. The instrument uses a solid-state laser to stimulate OSL from each grain individually. These grains are placed in a regular grid...

  15. Long-term optical stimulation of channelrhodopsin-expressing neurons to study network plasticity

    Science.gov (United States)

    Lignani, Gabriele; Ferrea, Enrico; Difato, Francesco; Amarù, Jessica; Ferroni, Eleonora; Lugarà, Eleonora; Espinoza, Stefano; Gainetdinov, Raul R.; Baldelli, Pietro; Benfenati, Fabio

    2013-01-01

    Neuronal plasticity produces changes in excitability, synaptic transmission, and network architecture in response to external stimuli. Network adaptation to environmental conditions takes place in time scales ranging from few seconds to days, and modulates the entire network dynamics. To study the network response to defined long-term experimental protocols, we setup a system that combines optical and electrophysiological tools embedded in a cell incubator. Primary hippocampal neurons transduced with lentiviruses expressing channelrhodopsin-2/H134R were subjected to various photostimulation protocols in a time window in the order of days. To monitor the effects of light-induced gating of network activity, stimulated transduced neurons were simultaneously recorded using multi-electrode arrays (MEAs). The developed experimental model allows discerning short-term, long-lasting, and adaptive plasticity responses of the same neuronal network to distinct stimulation frequencies applied over different temporal windows. PMID:23970852

  16. Long-term optical stimulation of channelrhodopsin-expressing neurons to study network plasticity.

    Science.gov (United States)

    Lignani, Gabriele; Ferrea, Enrico; Difato, Francesco; Amarù, Jessica; Ferroni, Eleonora; Lugarà, Eleonora; Espinoza, Stefano; Gainetdinov, Raul R; Baldelli, Pietro; Benfenati, Fabio

    2013-01-01

    Neuronal plasticity produces changes in excitability, synaptic transmission, and network architecture in response to external stimuli. Network adaptation to environmental conditions takes place in time scales ranging from few seconds to days, and modulates the entire network dynamics. To study the network response to defined long-term experimental protocols, we setup a system that combines optical and electrophysiological tools embedded in a cell incubator. Primary hippocampal neurons transduced with lentiviruses expressing channelrhodopsin-2/H134R were subjected to various photostimulation protocols in a time window in the order of days. To monitor the effects of light-induced gating of network activity, stimulated transduced neurons were simultaneously recorded using multi-electrode arrays (MEAs). The developed experimental model allows discerning short-term, long-lasting, and adaptive plasticity responses of the same neuronal network to distinct stimulation frequencies applied over different temporal windows.

  17. Gamma response characterizations of optically stimulated luminescence (OSL) affects personal dosimetry

    Science.gov (United States)

    Monthonwattana, S.; Esor, J.; Rungseesumran, T.; Intang, A.

    2017-06-01

    Optically Stimulated Luminescence (OSL) is the current technique of personal dosimetry changed by Nuclear Technology Service Center instead of Thermoluminescence dosimetry (TLD) because OSL has more advantages, such as repeat reading and elimination of heating process. In this study, OSL was used to test the gamma response characterizations. Detailed OSL investigation on personal dosimetry was carried out in the dose range of 0.2 - 3.0 mSv. The batch homogeneity was 7.66%. R2 value of the linear regression was 0.9997. The difference ratio of angular dependence at ± 60° was 8.7%. Fading of the reading was about 3%.

  18. Surface exposure dating of non-terrestrial bodies using optically stimulated luminescence: A new method

    DEFF Research Database (Denmark)

    Sohbati, Reza; Jain, Mayank; Murray, Andrew

    2012-01-01

    We propose a new method for in situ surface exposure dating of non-terrestrial geomorphological features using optically stimulated luminescence (OSL); our approach is based on the progressive emptying of trapped charge with exposure to light at depth into a mineral surface. A complete model...... will be applicable over the last 100 ka. The method is ideally suited to in situ measurement using existing technology developed for space applications, and so offers for the first time the realistic possibility of direct determination of exposure ages of young non-terrestrial surfaces. © 2012 Elsevier Inc. All...... rights reserved....

  19. A new sensitive system for measurement of thermally and optically stimulated luminescence

    DEFF Research Database (Denmark)

    Markey, B.G.; Bøtter-Jensen, L.; Poolton, N.R.J.

    1996-01-01

    optics of the system with a combination of ellipsoidal mirrors and light guides, which also serve to make the system more flexible in choice of excitation source when OSL measurements are required. A variety of new light sources might be employed, adapted to allow the most efficient wavelengths...... of excitation to be used for the particular dosemeter under study. The capabilities and characteristics of the new design are described, and comparison with the existing TL/OSL system is made throughout the article.......An automatic system developed at RisO National Laboratory for measuring thermally and optically stimulated luminescence (TL, OSL) is widely used for radiation dose measurements. In the present model, high excitation and detection efficiencies were attempted, but inevitably there is a constant...

  20. Low-dose environmental dosimetry using Thermo- and Optically Stimulated Luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Zacharias, N. [Laboratory of Archaometry, Institue of Materials Science, NCSR Demokritos, 15 310 Ag. Paraskevi, Attiki (Greece)], E-mail: zacharias@ims.demokritos.gr; Stuhec, M. [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Knezevic, Z. [Ruder Boskovic Institute, Bijenicka 54, 10002 Zagreb (Croatia); Fountoukidis, E. [School of Engineering, Department of Physics-Chemistry and Material Technology, TEI of Piraeus, 122 44 Egaleo, Attiki (Greece); Michael, C.T.; Bassiakos, Y. [Laboratory of Archaometry, Institue of Materials Science, NCSR Demokritos, 15 310 Ag. Paraskevi, Attiki (Greece)

    2007-09-21

    Within this study, five different types of material were used as luminescence dosimetry phosphors for recording environmental radiation doses. The material was TLD400 and TLD500 phosphors, quartz from two different geological origins (quartzite rock veins and quartz sand) and salt and the techniques were Thermo- and Optically Stimulated Luminescence. The phosphors were buried within homogenized and sieved natural soil for periods ranging from 1 to 19 weeks. The luminescence analysis examined for signal sensitivity, dose response and signal growth. The results report well-measured doses of only some weeks when using Optical Luminescence besides the well-studied TLD400/500 phosphors also for quartz and salt samples. With Thermoluminescence, only TLD400/500 could reliably monitor doses corresponding to some weeks. The study concludes that quartz and salt could be routinely used as dosimetry phosphors to correctly estimate doses resulted from only some months of average to low radiation environments.

  1. Optical stress probe: in-situ stress mapping with Raman and Photo-stimulated luminescence spectroscopy

    International Nuclear Information System (INIS)

    Freihofer, G; Poliah, L; Walker, K; Medina, A; Raghavan, S

    2010-01-01

    The optical stress probe system, developed in this work, provides a non-invasive method of monitoring and mapping the optical properties of a material during in situ stress tests. The design and construction of such a system was achieved by coupling a fiber optic probe based spectrometer system with an electromechanical loading system. This novel instrumentation integration enables the quantitative study of Raman or Photo-stimulated luminescence peak shifts with stress, known as piezospectroscopy. It further enables mapping of these spectral shifts over a surface of the specimen under load. To achieve this, a focusing method was developed that optimizes the intensity of specific optical bands of interest with the probe position. Individual software programs for the various systems that make up the instrumentation including the spectrometer, load frame and the XYZ stage were integrated and a single user interface was created. The system was calibrated by replicating published linear correlation between compressive stress and spectral peak position, 2.5cm -1 /GPa for polycrystalline alumina.

  2. Optically stimulated luminescence dating of the Huanghe river terrace in Lanzhou basin

    International Nuclear Information System (INIS)

    Wang Ping; Yuan Daoyang; Liu Xinwang; Jiang Hanchao

    2007-01-01

    In this paper, profile observation and geologic strata structure analysis on the third level terrace at Fanjiaping on the south bank of the Huanghe River in the Lanzhou basin were reported, and systemically collected samples of fluvial sediments and the overlying diluvium and aeolian loess were analyzed by optically stimulated luminescence (OSL). The granulometric and magnetic susceptibility samples from the fine grain sedimentary layer at the middle of the profile were collected at a 2.5 cm interval. According to simplified multiple aliquot dating on fine grain quartz of 16 optically stimulated luminescence samples and electron spin resonance (ESR) dating of the underlying early fluvial layer, the following chronology results of the strata profile of the third terrace were obtained. The under- lying early fluvial layer is of gravels that belong to Fanjiaping formation in early and middle Pleistogene. The river-bed sedimentation of the Huanghe River started about 80,000 years ago. The accumulation of mainly proluvial sediments started about 70,000 years ago. And the continuous loess accumulation began about 55,000 years ago. The age of formation of the third terrace of Huanghe River was estimated at about 70,000 years, corresponding to the time between the last interglacial period and the last glacial period in the late Pleistocene. (authors)

  3. Thermally and optically stimulated luminescence of new ZnO nano phosphors exposed to beta radiation

    Energy Technology Data Exchange (ETDEWEB)

    Cruz V, C.; Burruel I, S.E.; Grijalva M, H.; Chernov, V.; Bernal, R. [Universidad de Sonora, A.P. 130, 83000 Hermosillo, Sonora (Mexico)

    2006-07-01

    In this work, we report the thermoluminescence (TL) and the optically stimulated luminescence (OSL) of ZnO nano phosphors obtained by thermal annealing of ZnS powders synthesized by precipitation in a chemical bath deposition reaction. To obtain nanocrystalline ZnO, ZnS pellet-shaped samples were subjected to a sintering process at 700 C during 24 under air atmosphere. Some samples were exposed to beta particles in the 0.15-10.15 kGy dose range and the integrated thermoluminescence as a function of dose increased as dose increased, with no saturation clue for the tested doses. Computerized glow-curve deconvolution of the experimental TL curves in individual peaks revealed a second order kinetics. In order to test the BOSL (Blue Optically Stimulated Luminescence) response, samples were beta irradiated with doses up to 600 Gy, showing an increasing OSL intensity as dose increases. From the experimental results that we have obtained, we conclude that the new ZnO phosphors under investigation are good candidates to be used as dosimetric materials. (Author)

  4. Luminescence optically stimulated: theory and applications; Luminiscencia opticamente estimulada: teoria y aplicaciones

    Energy Technology Data Exchange (ETDEWEB)

    Rivera M, T.; Azorin N, J. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, 09340 Mexico D.F. (Mexico)

    2002-07-01

    The thermally stimulated luminescence (Tl) has occupied an important place in the Solid state physics (FES) by the flexibility of the phenomena, mainly for its applications in the fields of Radiation Physics (FR) and Medical Physics (MF). The reason of this phenomena lies in the fact of the electrons release by the action of heat. Under that same reason, it can be used the action of another stimulant agent for releasing the trapped electrons in the metastable states (EM), this agent is the light which has the same effect that the heat, giving as result the production of light photons at using light in the visible spectra, of different wavelength that the excitation light. This phenomena is called Luminescence optically stimulated (LOE). The LOE has a great impact in the Solid State Physics (FES), dating and now in the use of the phenomena as a dosimetric method, alternate to the Tl, for its use in the ionizing and non-ionizing radiations fields. (Author)

  5. Challenges for the application of optical stimulation in the cochlea for the study and treatment of hearing loss.

    Science.gov (United States)

    Richardson, Rachael T; Thompson, Alexander C; Wise, Andrew K; Needham, Karina

    2017-02-01

    Electrical stimulation has long been the most effective strategy for evoking neural activity from bionic devices and has been used with great success in the cochlear implant to allow deaf people to hear speech and sound. Despite its success, the spread of electrical current stimulates a broad region of neural tissue meaning that contemporary devices have limited precision. Optical stimulation as an alternative has attracted much recent interest for its capacity to provide highly focused stimuli, and therefore, potentially improved sensory perception. Given its specificity of activation, optical stimulation may also provide a useful tool in the study of fundamental neuroanatomy and neurophysiological processes. Areas covered: This review examines the advances in optical stimulation - infrared, nanoparticle-enhanced, and optogenetic-based - and its application in the inner ear for the restoration of auditory function following hearing loss. Expert opinion: Initial outcomes suggest that optogenetic-based approaches hold the greatest potential and viability amongst optical techniques for application in the cochlea. The future success of this approach will be governed by advances in the targeted delivery of opsins to auditory neurons, improvements in channel kinetics, development of optical arrays, and innovation of opsins that activate within the optimal near-infrared therapeutic window.

  6. Optically stimulated luminescence of ZnO obtained by thermal treatment of ZnS chemically synthesized

    International Nuclear Information System (INIS)

    Cruz V, C.; Burruel I, S.E.; Orante B, V.R.; Grijalva M, H.; Perez S, R.; Bernal, R.

    2005-01-01

    In this work, we report the optically stimulated luminescence (OSL) dosimetry of new nano phosphors of ZnO obtained by thermal annealing of chemically synthesized ZnS powder. The synthesized ZnS nano powder was compressed in order to form pellet shaped pellets, which were afterwards subjected to a thermal annealing at 700 C during 24 h under air atmosphere. X-ray diffraction (XRD) patterns and energy-disperse X-ray Spectrometry (EDS) analyses confirmed the transformation of ZnS to ZnO. Samples were exposed to several doses of beta radiation up to 600 Gy, and the optically stimulated luminescence with 470 nm wavelength light was recorded as a function of dose. The intensity of the OSL signal increases by increasing dose, for what it is concluded that these new phosphor materials are suitable to be used in optically stimulated luminescence dosimetry. (Author)

  7. Characteristics of stimulated emission from optically pumped freestanding GaN grown by hydride vapor-phase epitaxy

    CERN Document Server

    Lee, M H; Kim, S T; Chung, S H; Moon, D C

    1999-01-01

    In this study, we observed optically pumped stimulated emission at room temperature in quasi-bulk GaN prepared from thick-film GaN grown on a sapphire substrate by using hydride vapor-phase epitaxy and subsequent mechanical removal of the sapphire substrate. The stimulated emission from the surface and 1-mm-wide-cleaved cavity of the GaN was red-shifted compared to the spontaneous emission by increasing the optical pumping-power density, and the full width at half maximum (FWHM) of the peak decreased. The stimulated emission was demonstrated to have a highly TE-mode polarized nature, and the super-linear dependence of the integrated emission intensity on the excitation power indicated a threshold pump-power density of I sub t sub h = 2 MW/cm sup 2 for one set of stimulated emissions.

  8. Dimensionality reduction and dynamical filtering: Stimulated Brillouin scattering in optical fibers.

    Science.gov (United States)

    Setra, Rafael G; Arroyo-Almanza, Diana A; Ni, Zetian; Murphy, Thomas E; Roy, Rajarshi

    2015-08-01

    Stimulated Brillouin scattering (SBS) is a noise-driven nonlinear interaction between acoustical and optical waves. In optical fibers, SBS can be observed at relatively low optical powers and can severely limit signal transmission. Although SBS is initiated by high dimensional noise, it also exhibits many of the hallmarks of a complex nonlinear dynamical system. We report here a comprehensive experimental and numerical study of the fluctuations in the reflected Stokes wave produced by SBS in optical fibers. Using time series analysis, we demonstrate a reduction of dimensionality and dynamical filtering of the Stokes wave. We begin with a careful comparison of the measured average transmitted and reflected intensities from below the SBS threshold to saturation of the transmitted power. Initially the power spectra and correlation functions of the time series of the reflected wave fluctuations at the SBS threshold and above are measured and simulated. Much greater dynamical insight is provided when we study the scaling behavior of the intensity fluctuations using Hurst exponents and detrended fluctuation analysis for time scales extending over six orders of magnitude. At the highest input powers, we notice the emergence of three distinct dynamical scaling regimes: persistent, Brownian, and antipersistent. Next, we explore the Hilbert phase fluctuations of the intensity time series and amplitude-phase coupling. Finally, time-delay embedding techniques reveal a gradual reduction in dimensionality of the spatiotemporal dynamics as the laser input is increased toward saturation of the transmitted power. Through all of these techniques, we find a transition from noisier to smoother dynamics with increasing input power. We find excellent agreement between our experimental measurements and simulations.

  9. Dimensionality reduction and dynamical filtering: Stimulated Brillouin scattering in optical fibers

    Science.gov (United States)

    Setra, Rafael G.; Arroyo-Almanza, Diana A.; Ni, Zetian; Murphy, Thomas E.; Roy, Rajarshi

    2015-08-01

    Stimulated Brillouin scattering (SBS) is a noise-driven nonlinear interaction between acoustical and optical waves. In optical fibers, SBS can be observed at relatively low optical powers and can severely limit signal transmission. Although SBS is initiated by high dimensional noise, it also exhibits many of the hallmarks of a complex nonlinear dynamical system. We report here a comprehensive experimental and numerical study of the fluctuations in the reflected Stokes wave produced by SBS in optical fibers. Using time series analysis, we demonstrate a reduction of dimensionality and dynamical filtering of the Stokes wave. We begin with a careful comparison of the measured average transmitted and reflected intensities from below the SBS threshold to saturation of the transmitted power. Initially the power spectra and correlation functions of the time series of the reflected wave fluctuations at the SBS threshold and above are measured and simulated. Much greater dynamical insight is provided when we study the scaling behavior of the intensity fluctuations using Hurst exponents and detrended fluctuation analysis for time scales extending over six orders of magnitude. At the highest input powers, we notice the emergence of three distinct dynamical scaling regimes: persistent, Brownian, and antipersistent. Next, we explore the Hilbert phase fluctuations of the intensity time series and amplitude-phase coupling. Finally, time-delay embedding techniques reveal a gradual reduction in dimensionality of the spatiotemporal dynamics as the laser input is increased toward saturation of the transmitted power. Through all of these techniques, we find a transition from noisier to smoother dynamics with increasing input power. We find excellent agreement between our experimental measurements and simulations.

  10. The interpretation of quartz optically stimulated luminescence equivalent dose versus time plots

    International Nuclear Information System (INIS)

    Bailey, R.M.

    2000-01-01

    Numerical modelling has shown that the form of the quartz OSL shine plateau (hereafter 'D e (t)-plot') is influenced by the effects of phototransferred TL in the ∼110 deg. C region. It is suggested also that the presence of multiple OSL components (as described by Partial bleaching and the decay form characteristics of quartz OSL. Radiat. Meas., 27, 123-136. The form of the optically stimulated luminescence signal of quartz: implications of dating. Unpublished PhD thesis, University of London) affects the form of the D e (t)-plot. Laboratory measurements of a fully reset and artificially dosed sample yielded non-flat D e (t)-plots, the deviation being greater for the larger of the two simulated palaeodoses, in accordance with theoretical predictions. It is suggested that the so-called 'shine plateau' test is of limited use in assessing the bleaching history of quartz sediments

  11. Uncertainties associated with the use of optically stimulated luminescence in personal dosimetry

    International Nuclear Information System (INIS)

    Benevides, L.; Romanyukha, A.; Hull, F.; Duffy, M.; Voss, S.; Moscovitch, M.

    2011-01-01

    This study investigates several sources of uncertainty associated with the application of optically stimulated luminescence (OSL) to personal dosimetry. A commercial OSL system based on Al 2 O 3 :C was used for this study. First, it is demonstrated that the concept of repeated evaluation (readout) of the same dosemeter, often referred to as 're-analysis', can introduce uncertainty in the re-estimated dose. This uncertainty is associated with the fact that the re-analysis process depletes some of the populated traps, resulting in a continuous decrease of the OSL signal with each repeated reading. Furthermore, the rate of depletion may be dose-dependent. Second, it is shown that the previously reported light-induced fading in this system is the result of light leaks through miniature openings in the dosemeter badge. (authors)

  12. Stimulated Brillouin scattering continuous wave phase conjugation in step-index fiber optics.

    Science.gov (United States)

    Massey, Steven M; Spring, Justin B; Russell, Timothy H

    2008-07-21

    Continuous wave (CW) stimulated Brillouin scattering (SBS) phase conjugation in step-index optical fibers was studied experimentally and modeled as a function of fiber length. A phase conjugate fidelity over 80% was measured from SBS in a 40 m fiber using a pinhole technique. Fidelity decreases with fiber length, and a fiber with a numerical aperture (NA) of 0.06 was found to generate good phase conjugation fidelity over longer lengths than a fiber with 0.13 NA. Modeling and experiment support previous work showing the maximum interaction length which yields a high fidelity phase conjugate beam is inversely proportional to the fiber NA(2), but find that fidelity remains high over much longer fiber lengths than previous models calculated. Conditions for SBS beam cleanup in step-index fibers are discussed.

  13. High-speed all-optical logic inverter based on stimulated Raman scattering in silicon nanocrystal.

    Science.gov (United States)

    Sen, Mrinal; Das, Mukul K

    2015-11-01

    In this paper, we propose a new device architecture for an all-optical logic inverter (NOT gate), which is cascadable with a similar device. The inverter is based on stimulated Raman scattering in silicon nanocrystal waveguides, which are embedded in a silicon photonic crystal structure. The Raman response function of silicon nanocrystal is evaluated to explore the transfer characteristic of the inverter. A maximum product criterion for the noise margin is taken to analyze the cascadability of the inverter. The time domain response of the inverter, which explores successful inversion operation at 100 Gb/s, is analyzed. Propagation delay of the inverter is on the order of 5 ps, which is less than the delay in most of the electronic logic families as of today. Overall dimension of the device is around 755  μm ×15  μm, which ensures integration compatibility with the matured silicon industry.

  14. Optically stimulated luminescence techniques in retrospective dosimetry using single grains of quartz extracted from unheated materials

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov

    This work investigates the possibility of applying optically stimulated luminescence (OSL) in retrospective dose determinations using unheated materials. It focuses on identifying materials suitable for use in assessment of doses absorbed as a consequenceof radiation accidents (i.e. accident...... that the observed variability in the data is consistent with the sum (in quadrature) of a component,which depends on the number of photons detected from each grain, and a fixed component independent of light level. Dose depth profiles through laboratory irradiated concrete bricks have successfully been measured...... of using common household and workplace chemicals, such as table salt, washing powder and water softener, in retrospective dosimetry has been investigated. It is concluded that such materials should be considered as retrospective dosimeters inthe event of a radiation accident....

  15. Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography.

    Science.gov (United States)

    Robles, Francisco E; Fischer, Martin C; Warren, Warren S

    2016-01-11

    Stimulated Raman scattering (SRS) enables fast, high resolution imaging of chemical constituents important to biological structures and functional processes, both in a label-free manner and using exogenous biomarkers. While this technology has shown remarkable potential, it is currently limited to point scanning and can only probe a few Raman bands at a time (most often, only one). In this work we take a fundamentally different approach to detecting the small nonlinear signals based on dispersion effects that accompany the loss/gain processes in SRS. In this proof of concept, we demonstrate that the dispersive measurements are more robust to noise compared to amplitude-based measurements, which then permit spectral or spatial multiplexing (potentially both, simultaneously). Finally, we illustrate how this method may enable different strategies for biochemical imaging using phase microscopy and optical coherence tomography.

  16. Charge recombination processes in minerals studied using optically stimulated luminescence and time-resolved exo-electrons

    DEFF Research Database (Denmark)

    Tsukamoto, Sumiko; Murray, Andrew; Ankjærgaard, Christina

    2010-01-01

    electron concentration in the conduction band. In this study, TR-OSE and time-resolved optically stimulated luminescence (TR-OSL) were measured for the first time using quartz, K-feldspar and NaCl by stimulating the samples using pulsed blue LEDs at different temperatures between 50 and 250 °C after beta...... irradiation and preheating to 280 °C. The majority of TR-OSE signals from all the samples decayed much faster than TR-OSL signals irrespective of the stimulation temperatures. This suggests that the lifetime of OSL in these dosimeters arises mainly from the relaxation of an excited state of the recombination...

  17. Radiation dose response correlation between thermoluminescence and optically stimulated luminescence in quartz

    International Nuclear Information System (INIS)

    Oniya, E.O.; Polymeris, G.S.; Tsirliganis, N.C.; Kitis, G.

    2012-01-01

    The fast, linearly modulated optically stimulated luminescence (LM-OSL) component in quartz is the main dosimetric signal used for the dating applications of this material. Since the blue light stimulation (470 nm, 40 mW cm −2 ) time needed to obtain the fast LM-OSL component is less than 50 s the electron trapping levels responsible for it are still highly populated. In this way an active radiation history is created which could play an important role in the dosimetric characteristics of the fast OSL signal. In the present work the dose response behavior of the fast OSL signal is investigated in quartz samples with an annealed radiation history and quartz samples possessing an artificial radiation history. A computerized curve de-convolution analysis of the LM-OSL curves for 50 s stimulation time showed that it consists of three individual OSL components. The faster component C 1 with peak maximum time around 5 s has a linear dose response in virgin samples, which turns to a slight superlinearity as a function of the artificial radiation history. On the other hand the component C 2 with peak maximum time at 12 s is slightly superlinear which turns into strong superlinearity as a function of artificial radiation history. Finally, component C 3 with peak maximum time at about 45 s is strongly superlinear for both virgin samples and as a function of artificial radiation history. The implications to practical application are discussed. - Highlights: ► The fast OSL component consists of three components. ► The linearity of first fast component does not depend on radiation history. ► The linearity of second and third components depend on radiation history. ► The TL between 180 and 300 °C is the major source of OSL.

  18. Optically stimulated slowing of polar heavy-atom molecules with a constant beat phase

    Science.gov (United States)

    Yin, Yanning; Xu, Supeng; Xia, Meng; Xia, Yong; Yin, Jianping

    2018-04-01

    Polar heavy-atom molecules have been well recognized as promising candidates for precision measurements and tests of fundamental physics. A much slower molecular beam to increase the interaction time should lead to a more sensitive measurement. Here we theoretically demonstrate the possibility of the stimulated longitudinal slowing of heavy-atom molecules by the coherent optical bichromatic force with a constant beat phase. Taking the YbF meolecule as an example, we show that a rapid and short-distance deceleration of heavy molecules by a phase-compensation method is feasible with moderate conditions. A molecular beam of YbF with a forward velocity of 120 m/s can be decelerated below 10 m/s within a distance of 3.5 cm and with a laser irradiance for each traveling wave of 107.2 W/cm 2 . Our proposed slowing method could be a promising approach to break through the space constraint or the limited capture efficiency of molecules loadable into a magneto-optical trap in traditional deceleration schemes, opening the possibility for a significant improvement of the precision measurement sensitivity.

  19. Effect of inorganic salt on the dose sensitivity of polymer gel dosimeter

    International Nuclear Information System (INIS)

    Hayashi, Shin-ichiro; Fujiwara, Fumiya; Usui, Shuji; Tominaga, Takahiro

    2012-01-01

    The effect of inorganic salts, non-transition metal chlorides, on the dose sensitivity of methacrylic-acid-based polymer gel dosimeter is investigated. Dose-R 2 responses are obtained from magnetic resonance imaging data. Temperature increase due to exothermic polymerization reaction in the gel is also measured directly during irradiation. As a result, substantial increases in R 2 response are observed in the polymer gel dosimeter containing inorganic salt, especially with MgCl 2 . The sensitivity of the gel with 1.0 M MgCl 2 is approximately 2.8 times higher than that of without MgCl 2 . As the salt concentration increases, an increase of polymerization rate is also observed via the temperature measurements. These results indicate that inorganic salt acts as an accelerator for radiation-induced free-radical polymerization in methacrylic-acid-based gel. - Highlights: ► The effect of inorganic salt on the NMR dose sensitivity of polymer gel dosimeter. ► The high sensitivity of 3D dosimeter has been required for radiation treatment. ► The inorganic salt added, especially MgCl 2 , acts as a sensitizer in the dosimeter. ► The enhancement is correlated with the attractive ability of cations of the salts. ► The results may lead to a novel direction in the development of polymer gel dosimeters.

  20. Variable single-passband narrowband optical filter based on forward stimulated interpolarization scattering in photonic crystal fiber.

    Science.gov (United States)

    Qin, Yi; Sun, Junqiang; Du, Mingdi; Liao, Jianfei

    2012-09-01

    A variable transmission spectrum single-passband narrowband optical filter is proposed and experimentally demonstrated. It is based on forward stimulated interpolarization scattering (SIPS) in a photonic crystal fiber by applying a differential quadrature phase-shift keying modulation to the pump wave to broaden and shape the SIPS gain spectrum. By choosing the bit rate of the modulation data pattern, a flat-top steep-cutoff optical bandpass filter with a 3 dB bandwidth of 70 MHz and a 10 dB bandwidth of 90 MHz is realized. In addition, a variable narrowband optical notch filter is also realized by attenuation of the pump wave.

  1. Optically stimulated luminescence sensitivity changes in quartz due to repeated use in single aliquot readout: Experiments and computer simulations

    DEFF Research Database (Denmark)

    McKeever, S.W.S.; Bøtter-Jensen, L.; Agersnap Larsen, N.

    1996-01-01

    As part of a study to examine sensitivity changes in single aliquot techniques using optically stimulated luminescence (OSL) a series of experiments has been conducted with single aliquots of natural quartz, and the data compared with the results of computer simulations of the type of processes...

  2. Thermally and optically stimulated luminescence of AlN-Y2O3 ceramics after ionising irradiation

    DEFF Research Database (Denmark)

    Trinkler, L.; Bos, A.J.J.; Winkelman, A.J.M.

    1999-01-01

    Thermally (TL) and optically stimulated luminescence (OSL) were studied in AlN-Y2O3 ceramics after irradiation with ionising radiation. The extremely high TL sensitivity (approximately 60 times the sensitivity of LiF:Mg,Tl (TLD-100)) makes AlN-Y2O3 ceramics attractive as a TLD material. However...

  3. Optically stimulated luminescence (OSL) dating of quartzite cobbles from the Tapada do Montinho archaeological site (east-central Portugal)

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew S.; Buylaert, Jan-Pieter

    2012-01-01

    The burial age of an alluvially deposited cobble pavement at the Tapada do Montinho archaeological site (east-central Portugal) is investigated using optically stimulated luminescence (OSL) dating. Measurements on the cobbles (quartzite clasts) were carried out on intact slices and large aliquots...

  4. Thyroid-stimulating immunoglobulins indicate the onset of dysthyroid optic neuropathy.

    Science.gov (United States)

    Ponto, K A; Diana, T; Binder, H; Matheis, N; Pitz, S; Pfeiffer, N; Kahaly, G J

    2015-07-01

    Recognition of dysthyroid optic neuropathy (DON) requires sensitive diagnostic tools. Clinical assessment may fail to reliably evaluate the acuteness of DON especially if signs for inflammation are missing. Aim of this cross-sectional study was to assess the relationship between thyroid-stimulating immunoglobulins (TSI) and onset of DON. At a multidisciplinary orbital center, serum TSI levels were measured in 180 consecutive patients with thyroid eye disease (TED) and 302 healthy controls with a FDA-cleared cell-based bioassay using a chimeric TSH receptor and a CRE-dependent luciferase. Thirty of 180 (16.7 %) patients with TED had DON of recent onset or a past history of DON (post-DON). Optic disk swelling was present and visual-evoked potentials were pathologic in all eyes with DON of recent onset, but in one of 13 (7.7 %) with post-DON, only (p = 0.005). 19/20 (96 %) patients with DON of recent onset were TSI-positive. TSI was associated with DON of recent onset (OR: 20.96; 95 % CI 1.064-412.85, p = 0.045). All controls were TSI negative. TSI correlated with the clinical activity score (R = 0.70, p TSI-levels were noted in active vs. inactive TED (485.1 ± 132.3 vs. 277.7 ± 143.7 %, cut-off TSI-positive (p = 0.006). A discriminatory cut-point of 377 SRR % for TSI was determined based on a ROC analysis (sensitivity: 0.95, specificity: 0.8). Serum TSI levels identify patients with DON of recent onset requiring urgent therapy.

  5. Study of Optically Stimulated Luminescence of LiF:Mg,Ti for beta and gamma dosimetry

    International Nuclear Information System (INIS)

    Matsushima, Luciana C.; Veneziani, Glauco R.; Campos, Letícia L.

    2013-01-01

    Modern advances in radiation medicine – radiodiagnosis, radiotherapy and interventional radiography – each present dosimetry challenges for the medical physicist that did not exist previously. In all of these areas a constant balance has to be made between the treatment necessary to destroy the tumor and the unnecessary exposure of healthy tissue. Innovative applications of OSL dosimetry are now appearing in each of these areas to help the medical physicist and oncologist design the most effective, and least deleterious, treatment for their patients. High sensitivity, precise delivery of light, fast readout times, simpler readers and easier automation are the main advantages of OSL in comparison with TLD. This work aimed to study the application of OSL technique using lithium fluoride dosimeters doped with magnesium and titanium (LiF:Mg,Ti) for application in beta and gamma dosimetry. -- Highlights: •Study of Optically Stimulated Luminescence of LiF:Mg,Ti and microLiF:Mg,Ti. •OSL response of TLD-100 dosimeters to beta and gamma radiation. •Analysis of repeatability and lowest levels of detection of detectors LiF:Mg,Ti

  6. Optically stimulated luminescence of electronic components for forensic, retrospective, and accident dosimetry

    International Nuclear Information System (INIS)

    Inrig, E.L.; Godfrey-Smith, D.I.; Khanna, S.

    2008-01-01

    This study investigated the optically stimulated luminescence (OSL) response of electronic components found within portable electronic devices such as cell phones and pagers, portable computers, music and video players, global positioning system receivers, cameras, and digital watches. The analysis of components extracted from these ubiquitous devices was proposed for applications ranging from rapid accident dose reconstruction to the tracking and attribution of gamma-emitting radiological materials. Surface-mount resistors with alumina porcelain substrates consistently produced OSL following irradiation, with minimum detectable doses on the order of 10 mGy for a typical sample. Since the resistor ceramics were found to exhibit anomalous fading, dose reconstruction procedures were developed to correct for this using laboratory measurements of fading rates carried out over approximately 3 months. Two trials were conducted in which cellular phones were affixed to an anthropomorphic phantom and irradiated using gamma-ray sources; ultimately, analysis of the devices used in these trials succeeded in reconstructing doses in the range of 0.1-0.6Gy

  7. Optically stimulated luminescence dating of archaeological ceramics from Osvaldo and Lago Grande sites in central Amazon

    International Nuclear Information System (INIS)

    Hazenfratz, Roberto; Tudela, Diego R.G.; Munita, Casimiro S.; Mittani, Juan C.R.; Tatumi, Sonia H.

    2013-01-01

    Thermoluminescence (TL) and optically stimulated luminescence (OSL) dating are two important techniques for dating archaeological and geological material, especially suitable for archaeological ceramics, where samples for 14 C dating are not available. In this work, five pottery shards from Osvaldo and Lago Grande archaeological sites were dated by OSL. For measurements, it was used the SAR protocol. The annual dose rates were estimated by the contents of U, Th and K, determined by instrumental neutron activation analysis (INAA) of the pottery shards and clay samples near both sites. Lago Grande and Osvaldo represent a microcosm of the region, and their proximity and high density of archaeological record turn them interesting to study possible relations of cultural and/or commercial exchange. Calculations showed that the water content is an important variable that cannot be neglected in OSL dating of pottery shards from central Amazon, due to the high humidity in regional soils. The results between 867 ± 101 and 1154 ± 62 years AD agreed with the average time span for the archaeological sites occupation found in the literature. (author)

  8. Response of optically stimulated luminescence dosimeters subjected to X-rays in diagnostic energy range

    International Nuclear Information System (INIS)

    Musa, Y; Hashim, S; Karim, M K A; Ang, W C; Salehhon, N; Bakar, K A

    2017-01-01

    The use of optically stimulated luminescence (OSL) for dosimetry applications has recently increased considerably due to availability of commercial OSL dosimeters (nanoDots) for clinical use. The OSL dosimeter has a great potential to be used in clinical dosimetry because of its prevailing advantages in both handling and application. However, utilising nanoDot OSLDs for dose measurement in diagnostic radiology can only be guaranteed when the performance and characteristics of the dosimeters are apposite. In the present work, we examined the response of commercially available nanoDot OSLD (Al 2 O 3 :C) subjected to X-rays in general radiography. The nanoDots response with respect to reproducibility, dose linearity and signal depletion were analysed using microStar reader (Landauer, Inc., Glenwood, IL). Irradiations were performed free-in-air using 70, 80 and 120 kV tube voltages and tube currents ranging from 10 – 100 mAs. The results showed that the nanoDots exhibit good linearity and reproducibility when subjected to diagnostic X-rays, with coefficient of variations (CV) ranging between 2.3% to 3.5% representing a good reproducibility. The results also indicated average of 1% signal reduction per readout. Hence, the nanoDots showed a promising potential for dose measurement in general X-ray procedure. (paper)

  9. Spatio-temporal characteristics of inhibition mapped by optical stimulation in mouse olfactory bulb

    Directory of Open Access Journals (Sweden)

    Alexander eLehmann

    2016-03-01

    Full Text Available Mitral and tufted cells (MTCs of the mammalian olfactory bulb (OB are connected via dendrodendritic synapses with inhibitory interneurons in the external plexiform layer. The range, spatial layout and temporal properties of inhibitory interactions between MTCs mediated by inhibitory interneurons remain unclear. Therefore we tested for inhibitory interactions using an optogenetic approach. We optically stimulated MTCs expressing channelrhodopsin-2 in transgenic mice, while recording from individual MTCs in juxtacellular or whole-cell configuration in vivo. We used a spatial noise stimulus for mapping interactions between MTCs belonging to different glomeruli in the dorsal bulb. Analyzing firing responses of MTCs to the stimulus, we did not find robust lateral inhibitory effects that were spatially specific. However, analysis of sub-threshold changes in the membrane potential revealed evidence for inhibitory interactions between MTCs that belong to different glomerular units. These lateral inhibitory effects were short-lived and spatially specific. MTC response maps showed hyperpolarizing effects radially extending over more than 5 glomerular diameters. The inhibitory maps exhibited non-symmetrical yet distance-dependent characteristics.

  10. Thyroid dose measurement in patients undergoing to digital orthopantomography using optical stimulation dosimeters

    International Nuclear Information System (INIS)

    Gutierrez M, J. G.; Lopez V, A.; Rivera M, T.; Avalos P, L. Y.

    2016-10-01

    In this paper we present the study of the thyroid equivalent dose in 300 patients undergoing to digital orthopantomography for dental treatment purposes using optical stimulation dosimeters (OSL) as in-vivo dosimeters, in order to verify if this is within acceptable parameters to prevent stochastic risks and to evaluate the possible risks caused by the technique used for this type of study (66 kv, 5 m A, 14.1 s). Three OSL dosimeters were used per patient, which were placed by the physician on the skin above the thyroid gland (using anatomical references and palpation); the information of the patients was divided by neck size and sex, finding a slight increase in the equivalent dose for female and small size patient, this combination being the group that was submitted to a higher dose. The results obtained were compared with similar studies performed on anthropomorphic mannequins with TLD dosimeters obtaining lower results. The equivalent dose found even though is below the threshold stochastic damage must be motorized for radiological protection and registration purposes. (Author)

  11. Effects of gravitational and optical stimulation on the perception of target elevation

    Science.gov (United States)

    Cohen, M. M.; Stoper, A. E.; Welch, R. B.; DeRoshia, C. W.

    2001-01-01

    To examine the combined effects of gravitational and optical stimulation on perceived target elevation, we independently altered gravitational-inertial force and both the orientation and the structure of a background visual array. While being exposed to 1.0, 1.5, or 2.0 Gz in the human centrifuge at NASA Ames Research Center, observers attempted to set a target to the apparent horizon. The target was viewed against the far wall of a box that was pitched at various angles. The box was brightly illuminated, had only its interior edges dimly illuminated, or was kept dark. Observers lowered their target settings as Gz was increased; this effect was weakened when the box was illuminated. Also, when the box was visible, settings were displaced in the same direction as that in which the box was pitched. We attribute our results to the combined influence of otolith-oculomotor mechanisms that underlie the elevator illusion and visual-oculomotor mechanisms (optostatic responses) that underlie the perceptual effects of viewing pitched visual arrays.

  12. Pottery versus sediment: Optically stimulated luminescence dating of the Neolithic Vinča culture, Serbia

    DEFF Research Database (Denmark)

    Bate, Stephen; Stevens, Thomas; Buylaert, Jan-Pieter

    2017-01-01

    (De) values were investigated for sediment samples using 63–90 μm grains on large and small aliquots, and single-grain laser luminescence (SGLL), and for pottery samples using large aliquots of 4–11 μm grains. The effects of changing water content and the different techniques available to establish...... radionuclide concentration were explored for their impacts on dose rate (Dr) estimates. Ages for two pottery samples of 6.74 ± 0.37 ka and 7.04 ± 0.47 ka are in line with the existing AMS radiocarbon chronology for the site and are regarded as the best dates available. Sediment samples at Vinča show poor......Optically stimulated luminescence (OSL) dating was applied to the Neolithic Vinča culture's type-site, Vinča Belo-Brdo, to establish best protocols for routine luminescence dating of similar Holocene sites, critical in understanding Neolithic to Chalcolithic cultural development. Equivalent dose...

  13. Physical properties limiting the application of thermoluminescence (TL) and Optically stimulated luminescence (OSL) for radiation dosimetry

    International Nuclear Information System (INIS)

    Chen, R.

    2005-01-01

    In the applications in thermoluminescence (TL) and optically stimulated luminescence (OSL) dosimetry, as well as archaeological and geological dating, a number of features of the material used are of importance. An ideal dosimetric material should have high sensitivity to the relevant radiation, reproducible monotonically increasing dose dependence function, preferably linear, and no dependence of the sensitivity on the radiation history, heating (in TL) and light exposure (in OSL). In addition one hopes that no dose-rate effects take place and that no fading of the emitted signal occur prior to the read-out. The complex processes that take place during the excitation stage and the heating (in TL) or illumination (in OSL) are, however, such that in practically all of the dosimetric materials at least some of these ill-effects do take place. The possible occurrence of these effects is explained here using the rather basic concepts of existing trapping states and recombination centers which are being filled during the irradiation of the samples and emptied during the heating or illumination. The models used are related mainly to uniform excitation of the dosimetric samples, which is basically the case in X-ray, UV, B and irradiations. An important element of the models discussed is the existence of competitor trapping states and recombination centers. (Author)

  14. Thermally and optically stimulated radiative processes in Eu and Y co-doped LiCaAlF6 crystal

    International Nuclear Information System (INIS)

    Fukuda, Kentaro; Yanagida, Takayuki; Fujimoto, Yutaka

    2015-01-01

    Yttrium co-doping was attempted to enhance dosimeter performance of Eu doped LiCaAlF 6 crystal. Eu doped and Eu, Y co-doped LiCaAlF 6 were prepared by the micro-pulling-down technique, and their dosimeter characteristics such as optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) were investigated. By yttrium co-doping, emission intensities of OSL and TSL were enhanced by some orders of magnitude. In contrast, scintillation characteristics of yttrium co-doped crystal such as intensity of prompt luminescence induced by X-ray and light yield under neutron irradiation were degraded

  15. Single photon detection and signal analysis for high sensitivity dosimetry based on optically stimulated luminescence with beryllium oxide

    Science.gov (United States)

    Radtke, J.; Sponner, J.; Jakobi, C.; Schneider, J.; Sommer, M.; Teichmann, T.; Ullrich, W.; Henniger, J.; Kormoll, T.

    2018-01-01

    Single photon detection applied to optically stimulated luminescence (OSL) dosimetry is a promising approach due to the low level of luminescence light and the known statistical behavior of single photon events. Time resolved detection allows to apply a variety of different and independent data analysis methods. Furthermore, using amplitude modulated stimulation impresses time- and frequency information into the OSL light and therefore allows for additional means of analysis. Considering the impressed frequency information, data analysis by using Fourier transform algorithms or other digital filters can be used for separating the OSL signal from unwanted light or events generated by other phenomena. This potentially lowers the detection limits of low dose measurements and might improve the reproducibility and stability of obtained data. In this work, an OSL system based on a single photon detector, a fast and accurate stimulation unit and an FPGA is presented. Different analysis algorithms which are applied to the single photon data are discussed.

  16. Progress in Direct Dating of Tephra via Thermo- and Optically Stimulated Luminescence

    Science.gov (United States)

    Clark-Balzan, L.; Smith, V.; Preusser, F.

    2016-12-01

    Luminescence dating utilizes natural dosimeters (minerals and mineralloids) to calculate either time elapsed since crystallization or the last exposure to light or intense heat. Direct dating of volcanic materials via luminescence has been attempted for nearly fifty years with varying degrees of success: dim luminescence signals, anomalous signal loss (`fading') from volcanogenic minerals, incomplete mineral separation, and mineralogical and geochemical variability have been problematic (Fattahi and Stokes, 2003). Recent advances in measurement protocols to probe signals less prone to anomalous fading (Tsukamoto et al., 2007; 2010), and the development of equipment that allows direct imaging of luminescence-emitting grains via EMCCD cameras (Clark-Balzan and Schwenninger, 2012) offer new opportunities for tephra dating. The lack of available luminescence data on a wide variety of tephra, however, makes it difficult to predict which measurement techniques will be generally applicable given presumed high inter- and intra-sample variability. Therefore we present first results from a systematic characterization of luminescence emissions from a geochemically and geographically diverse body of tephras. Spectrometric analysis of luminescence emitted from plagioclase, glass, and quartz fractions during thermal and optical stimulation provide key data for optimization and testing of measurement protocols. We also show preliminary results of EMCCD imaging of both mineral separates and bulk tephras, emphasizing identification and characterization of mineral constituents and luminescence properties via the simultaneous measurement of many grains. EMCCD imaging allows luminescence characterization on the single grain level, thereby revealing variability between grains which cannot be measured via standard spectromectric techniques. Clark-Balzan, L., Schwenninger, J.-L., 2012, Radiation Measurements, v. 47, pp. 797-802. Fattahi, M., Stokes, S., 2003, Earth Science Reviews, v. 62

  17. Optically stimulated luminescence techniques in retrospective dosimetry using single grains of quartz extracted from unheated materials

    International Nuclear Information System (INIS)

    Joerkov Thomsen, Kristina

    2004-02-01

    This work investigates the possibility of applying optically stimulated luminescence (OSL) in retrospective dose determinations using unheated materials. It focuses on identifying materials suitable for use in assessment of doses absorbed as a consequence of radiation accidents (i.e. accident dosimetry). Special attention has been paid to quartz extracted from unheated building materials such as concrete and mortar. The single-aliquot regeneration-dose (SAR) protocol has been used to determine absorbed doses in small aliquots as well as single grains of quartz. It is shown that OSL measurements of single grains of quartz extracted from poorly-bleached building materials can provide useful information on radiation accident doses, even when the luminescence sensitivity is low. Sources of variance in well-bleached single grain dose distributions have been investigated in detail and it is concluded that the observed variability in the data is consistent with the sum (in quadrature) of a component, which depends on the number of photons detected from each grain, and a fixed component independent of light level. Dose depth profiles through laboratory irradiated concrete bricks have successfully been measured and minimum detection limits of less than 100 mGy are derived. Measurements of thermal transfer in single grains of poorly-bleached quartz show that thermal transfer is variable on a grain-to-grain basis and that it can be a source of variance in single-grain dose distributions. Furthermore, the potential of using common household and workplace chemicals, such as table salt, washing powder and water softener, in retrospective dosimetry has been investigated. It is concluded that such materials should be considered as retrospective dosimeters in the event of a radiation accident. (au)

  18. Constraining Middle Pleistocene Glaciations in Birmingham, England; Using Optical Stimulated Luminescence (OSL) Dating.

    Science.gov (United States)

    Gibson, S. M.; Gibbard, P. L.; Bateman, M. D.; Boreham, S.

    2014-12-01

    Birmingham is built on a complex sequence of Middle Pleistocene sediments, representing at least three lowland glaciations (MIS12, MIS6, and MIS2). British Geological Survey mapping accounts 75% of the land mass as Quaternary deposits; predominantly glacial-sandy tills, glacial-fluvial sands, clays and organic silts and peats. Understanding the age of fluvial-glacial outwash, related to specific glaciations, is critical in establishing a Geochronology of Birmingham. Shotton (1953) found a series of Middle Pleistocene glacial sediments, termed the Wolstonian, intermediate in age between MIS11 and MIS5e Interglacial's. Uncertainty surrounding the relation to East Anglian sequences developed by Rose (1987) implies Birmingham sequences should be referred to MIS12. Despite this, younger Middle Pleistocene glacial sequences occur in Birmingham, yet uncertainty has deepened over our understanding of the complex, inaccessible sediments, especially as deposits have similar extent with MIS2 sequences. Five Optical Stimulated Luminescence (OSL) dates from three sites around Birmingham have been sampled. East of Birmingham, ice advanced from the Irish Sea and later the North East. In Wolston, a sample of outwash sand, associated with the Thurssington Till, is dated. In Meriden, two samples of outwash sands, associated with a distal Oadby Till, are dated. West of Birmingham, ice advanced from the Welsh Ice Sheet. In Seisdon, two samples of an Esker and outwash sand, associated with a Ridgeacre Till, are dated. Correlation of OSL dates provide an important constraint on understanding the history of Birmingham. Using GSI3D modeling to correlate geochronology and sedimentology, the significance of OSL dating can be understood within the complex sequences (and regional stratigraphy), complimented by Cosmogenic and Palynology dates taken in South West and North East. OSL dating on Birmingham's outwash sands, deposited by extensive repeated Middle Pleistocene glaciations, asserts the

  19. Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications

    Directory of Open Access Journals (Sweden)

    Pradhan A

    2008-01-01

    Full Text Available During the last 10 years, optically stimulated luminescence (OSL has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al 2 O 3 :C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al 2 O 3 :C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF 3 :Eu 2+ appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al 2 O 3 :C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become

  20. A polymeric dosimeter film based on optically-stimulated luminescence for dose measurements below 1 kGy

    International Nuclear Information System (INIS)

    Kovacs, A.; Baranyai, M.; Wojnarovits, L.; Slezsak, I.; McLaughlin, W.L.; Miller, S.D.; Miller, A.; Fuochi, P.G.; Lavalle, M.

    1999-01-01

    A new potential dosimetry system 'Sunna' containing a microcrystalline dispersion of an optically-stimulated fluor in a plastic matrix has been recently developed to measure and image high doses. Our previous investigations have revealed that the new dosimeter system is capable of measuring absorbed doses in the dose range of 1-100 kGy. The optically-stimulated luminescence (OSL) analysis is based on the blue light stimulation of the colour center states produced upon irradiation, and the intensity of the resulting red-light emission is used to measure absorbed dose. This analysis is carried out with a simple table-top fluorimeter developed for this purpose having also the ability to calculate the mathematical formula of the calibration function. The Sunna dosimeter was recently investigated for potential use in lower dose range below 1 kGy. These investigations have shown that the film is suitable for measuring doses in the range of 1-1000 Gy for both electron and gamma radiation. To test the applicability of the film, its reproducibility, stability, sensitivity to ambient and UV light and irradiation temperature were measured. The stability of the dosimeter was investigated by monitoring the change of the OSL signal with storage time after irradiation. Further experiments proved the homogeneity of the film with respect to thickness variation, and limited differences in its response were found between batches. (author)

  1. Photo-stimulated electro-optic response of liquid-crystalline system with trans-cis photo-isomerizable agent

    International Nuclear Information System (INIS)

    Hadjichristov, G B; Marinov, Y G; Yelamaggad, C V

    2014-01-01

    A rather strong photo-stimulated enhancement of photo-induced bend flexoelectric effect based on trans-cis photoisomerization of azo bond was found in a guest-host system formed from the nematic liquid crystal (LC) N-(4-methoxybenzylidene)-4-butylaniline (MBBA) as a host, and the azobenzene LC 4-hexyloxybenzoloxy-4'-cyanoazobenzene, as a guest photoactive agent at 1 wt.% concentration. Upon application of electric field, thin homeotropic layers of thickness 100 pm containing this photo-sensitized LC mixture were investigated as subjected to a relatively weak illumination with UV light (λ = 375 nm, from narrow-band light-emitting diode, LED). The stimulation of the photoactive electro-optic response of azobenzene-doped MBBA (owing to enhanced photo-induced bend flexoelectric effect driven by the photo-isomerizable dopants) was achieved by pre-resonant excitation of the photoactive agent. The degree of the effect measured is of potential interest for thin-film photoactive electro-optic applications. The UV light-induced effect in azobenzene-doped MBBA was reversible; the back (relaxation) process was stimulated by light in the blue from a LED with broadband spectrum centered at 455 nm

  2. Postsynaptic potentials recorded in neurons of the cat's lateral geniculate nucleus following electrical stimulation of the optic chiasm.

    Science.gov (United States)

    Bloomfield, S A; Sherman, S M

    1988-12-01

    1. We recorded intracellularly from X and Y cells of the cat's lateral geniculate nucleus and measured the postsynaptic potentials (PSPs) evoked from electrical stimulation of the optic chiasm. We used an in vivo preparation and computer averaged the PSPs to enhance their signal-to-noise ratio. 2. The vast majority (46 of 50) of our sample of X and Y cells responded to stimulation of the optic chiasm with an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP); these were tentatively identified as relay cells. We quantified several parameters of these PSPs, including amplitude, latency, time to peak (i.e., rise time), and duration. 3. Among the relay cells, the latencies of both the EPSP and action potential evoked by optic chiasm stimulation were shorter in Y cells than in X cells. Furthermore, the difference between the latencies of the EPSP and action potential was shorter for Y cells than for X cells. This means that the EPSPs generated in Y cells reached threshold for generation of action potentials faster than did those in X cells. The EPSPs of Y cells also displayed larger amplitudes and faster rise times than did those in X cells, but neither of these distinctions was sufficient to explain the shorter latency difference between the EPSP and action potential for Y cells. 4. The EPSPs recorded in relay Y cells had longer durations than did those in relay X cells. Our data suggest that the subsequent IPSP actively terminates the EPSP, which, in turn, suggests that the time interval between EPSP and IPSP onsets is longer in Y cells than in X cells. Furthermore, we found that, for individual Y cells, the latency and duration of the evoked EPSP were inversely related. These observations lead to the conclusion that the latency of IPSPs activated from the optic chiasm is relatively constant among Y cells and thus independent of the EPSP latencies. Thus the excitation and inhibition produced in individual geniculate Y

  3. Laser stimulating ST36 with optical fiber induce blood component changes in mice: a Raman spectroscopy study.

    Science.gov (United States)

    Zhang, Heng; Chen, Zhenyi; Wu, Jiping; Chen, Na; Xu, Wenjie; Li, Taihao; Liu, Shupeng

    2018-02-15

    ST36 is a commonly-used acupoint in traditional Chinese medicine (TCM) for treatment of inflammations, pains and gastrointestinal disturbs. For decades, the low power laser acupuncture has been widely applied as an alternative therapy to traditional metal needle acupuncture and achieved relatively fine therapeutic effect for ST36-related symptoms with reduction of uncomfortableness and infection risks. However its disadvantages of low penetrativity and lack of manipulation skills limit its potential performance. An optical fiber laser acupuncture introduced by the previous study combines traditional needling acupuncture and the laser stimulation together, making a stronger therapeutic effect and showing a potential value in clinical application. To evaluate its acupunctural effect on blood, mice are taken as experimental model and Raman spectroscopic technique is used to analysis the changes of blood components after stimulating on ST36. The results show that both the traditional needling acupuncture and optical fiber acupuncture could lead to some spectral changes of blood in mice. This study explores the optical fiber acupuncture's effect on blood in mice using Raman spectroscopy technique for mechanism of acupuncture therapy. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Extending the upper age limit for luminescence dating using the thermally transferred optically stimulated luminescence signal from quartz

    Science.gov (United States)

    Duller, Geoff A. T.; Wintle, Ann G.

    2010-05-01

    The optically stimulated luminescence (OSL) signal from quartz has been exploited for the last 20 years to date heated and unheated materials. While methods based on this signal have been extremely successful and are now widely adopted in laboratories around the world, growth of the signal with dose is affected by saturation and this commonly limits application to samples with equivalent doses of ~100 to 300 Gy. In most environments this limits application of the method to the last 100-150 ka. Studies of OSL from quartz in the late 1980's showed that if the OSL signal from a sample was reduced to background level by measurement, and the sample then heated, further optical stimulation gave a significant signal. This recuperated OSL was viewed as a problem to be avoided, particularly for young samples. Three years ago papers were published showing that this recuperated signal has the potential to be valuable in dosimetry, and in particular that the signal continues to grow to doses in excess of 10,000 Gy offering the possibility of extending the age range over which quartz can be used to as much as 1 Ma. The first work on this signal was undertaken on fine grain quartz extracted from Chinese loess, and ages back to the Brunhes-Matuyama boundary were obtained. The signal is now commonly referred to as thermally transferred optically stimulated luminescence (TT-OSL). Intense research on the signal has focussed on a number of areas, including, (a) understanding the origin of the charge measured in TT-OSL, (b) improving methods for measuring the TT-OSL signal, and (c) developing protocols for using TT-OSL in dose estimation, and these are reviewed in this presentation.

  5. Optical stimulation of the hearing and deaf cochlea under thermal and stress confinement condition

    Science.gov (United States)

    Schultz, M.; Baumhoff, P.; Kallweit, N.; Sato, M.; Krüger, A.; Ripken, T.; Lenarz, T.; Kral, A.

    2014-03-01

    There is a controversy, to which extend cochlear stimulation with near infrared laser pulses at a wavelength of 1860 nm is based on optoacoustic stimulation of intact hair cells or -in contrast- is based on direct stimulation of the nerve cells in absence of functional hair cells. Thermal and stress confinement conditions apply, because of the pulse duration range (5 ns, 10 μs-20 ms) of the two lasers used. The dependency of the signal characteristics on pulse peak power and pulse duration was investigated in this study. The compound action potential (CAP) was measured during stimulation of the cochlea of four anaesthetized guinea pigs, which were hearing at first and afterwards acutely deafened using intracochlear neomycin-rinsing. For comparison hydrophone measurements in a water tank were performed to investigate the optoacoustic signals at different laser interaction regimes. With rising pulse peak power CAPs of the hearing animals showed first a threshold, then a positively correlated and finally a saturating dependency. CAPs also showed distinct responses at laser onset and offset separated with the pulse duration. At pulse durations shorter than physiological response times the signals merged. Basically the same signal characteristics were observed in the optoacoustic hydrophone measurements, scaled with the sensitivity and response time of the hydrophone. Taking together the qualitative correspondence in the signal response and the absence of any CAPs in deafened animals our results speak in favor of an optoacoustic stimulation of intact hair cells rather than a direct stimulation of nerve cells.

  6. Stimulated emission and optical gain in AlGaN heterostructures grown on bulk AlN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wei, E-mail: wguo2@ncsu.edu; Bryan, Zachary; Kirste, Ronny; Bryan, Isaac; Hussey, Lindsay; Bobea, Milena; Haidet, Brian; Collazo, Ramón; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States); Xie, Jinqiao; Mita, Seiji [HexaTech, Inc., 991 Aviation Pkwy, Suite 800, Morrisville, North Carolina 27560 (United States); Gerhold, Michael [Engineering Science Directorate, Army Research Office, P.O. BOX 12211, Research Triangle Park, North Carolina 27703 (United States)

    2014-03-14

    Optical gain spectra for ∼250 nm stimulated emission were compared in three different AlGaN-based structures grown on single crystalline AlN substrates: a single AlGaN film, a double heterostructure (DH), and a Multiple Quantum Well (MQW) structure; respective threshold pumping power densities of 700, 250, and 150 kW/cm{sup 2} were observed. Above threshold, the emission was transverse-electric polarized and as narrow as 1.8 nm without a cavity. The DH and MQW structures showed gain values of 50–60 cm{sup −1} when pumped at 1 MW/cm{sup 2}. The results demonstrated the excellent optical quality of the AlGaN-based heterostructures grown on AlN substrates and their potential for realizing electrically pumped sub-280 nm laser diodes.

  7. Optical Generation of 80 GHz Downstream Data in Radio over Fiber System Based on Stimulated Brillouin Scattering

    Directory of Open Access Journals (Sweden)

    Husaini M.M.H

    2017-01-01

    Full Text Available In this work, we proposed Stimulated Brillouin Scattering (SBS in an optical generation of millimeter waves (mm-waves for radio over fiber (RoF system with the transmission of 2.5 Gbps data rate. SBS method is achieved by imposing continuous wave (CW laser in a single mode optical fiber (SMF via Mach-Zehnder Modulator (MZM with Erbium-Doped Fiber Amplifier (EDFA and two pump lasers. Mm-waves signal of 80 GHz was generated from a 40 GHz radio frequency (RF synthesizer. Simulation result and the analysis comparison of effective light power are investigated with different SMF loop length from 20 km until 120 km. The performance of SBS system is analysed and the generated of millimeter waves signal can be transmit with length up to 120 km based on eye pattern and Bit Error Rate (BER curve.

  8. Assessment of inhalation dose sensitivity by physicochemical properties of airborne particulates containing naturally occurring radioactive materials

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Si Young; Choi, Cheol Kyu; Kim, Yong Geon; Choi, Won Chul; Kim, Kwang Pyo [Kyung Hee University, Seoul (Korea, Republic of)

    2015-12-15

    Facilities processing raw materials containing naturally occurring radioactive materials (NORM) may give rise to enhanced radiation dose to workers due to chronic inhalation of airborne particulates. Internal radiation dose due to particulate inhalation varies depending on particulate properties, including size, shape, density, and absorption type. The objective of the present study was to assess inhalation dose sensitivity to physicochemical properties of airborne particulates. Committed effective doses to workers resulting from inhalation of airborne particulates were calculated based on International Commission on Radiological Protection 66 human respiratory tract model. Inhalation dose generally increased with decreasing particulate size. Committed effective doses due to inhalation of 0.01μm sized particulates were higher than doses due to 100μm sized particulates by factors of about 100 and 50 for {sup 238}U and {sup 230}Th, respectively. Inhalation dose increased with decreasing shape factor. Shape factors of 1 and 2 resulted in dose difference by about 18 %. Inhalation dose increased with particulate mass density. Particulate mass densities of 11 g·cm{sup -3} and 0.7 g·cm{sup -3} resulted in dose difference by about 60 %. For {sup 238}U, inhalation doses were higher for absorption type of S, M, and F in that sequence. Committed effective dose for absorption type S of {sup 238}U was about 9 times higher than dose for absorption F. For {sup 230}Th, inhalation doses were higher for absorption type of F, M, and S in that sequence. Committed effective dose for absorption type F of {sup 230}Th was about 16 times higher than dose for absorption S. Consequently, use of default values for particulate properties without consideration of site specific physiochemical properties may potentially skew radiation dose estimates to unrealistic values up to 1-2 orders of magnitude. For this reason, it is highly recommended to consider site specific working materials and

  9. Construction and use of a zebrafish heart voltage and calcium optical mapping system, with integrated electrocardiogram and programmable electrical stimulation

    Science.gov (United States)

    Lin, Eric; Craig, Calvin; Lamothe, Marcel; Sarunic, Marinko V.; Beg, Mirza Faisal

    2015-01-01

    Zebrafish are increasingly being used as a model of vertebrate cardiology due to mammalian-like cardiac properties in many respects. The size and fecundity of zebrafish make them suitable for large-scale genetic and pharmacological screening. In larger mammalian hearts, optical mapping is often used to investigate the interplay between voltage and calcium dynamics and to investigate their respective roles in arrhythmogenesis. This report outlines the construction of an optical mapping system for use with zebrafish hearts, using the voltage-sensitive dye RH 237 and the calcium indicator dye Rhod-2 using two industrial-level CCD cameras. With the use of economical cameras and a common 532-nm diode laser for excitation, the rate dependence of voltage and calcium dynamics within the atrial and ventricular compartments can be simultaneously determined. At 140 beats/min, the atrial action potential duration was 36 ms and the transient duration was 53 ms. With the use of a programmable electrical stimulator, a shallow rate dependence of 3 and 4 ms per 100 beats/min was observed, respectively. In the ventricle the action potential duration was 109 ms and the transient duration was 124 ms, with a steeper rate dependence of 12 and 16 ms per 100 beats/min. Synchronous electrocardiograms and optical mapping recordings were recorded, in which the P-wave aligns with the atrial voltage peak and R-wave aligns with the ventricular peak. A simple optical pathway and imaging chamber are detailed along with schematics for the in-house construction of the electrocardiogram amplifier and electrical stimulator. Laboratory procedures necessary for zebrafish heart isolation, cannulation, and loading are also presented. PMID:25740339

  10. Optically stimulated phosphorescence in orthoclase feldspar over the millisecond to second time scale

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank

    2010-01-01

    In the past, time-resolved IR stimulated luminescence (TR-IRSL) curves from feldspar have mainly been measured over a few hundred μs with the purpose of estimating the lifetimes of the components. In this study, we present the decay form of time-resolved IRSL and IR stimulated phosphorescence (IRSP......-time duration. The data on thermal dependence of these signals might suggest that the decay behaviour of the time-resolved IRSL and phosphorescence signals mainly reflect the occupancy of electrons in the band tail states with a significant contribution from the shallow traps. This interpretation is supported...

  11. Suppression of Stimulated Brillouin Scattering in Optical Fibers Using a Linearly Chirped Diode Laser

    Science.gov (United States)

    2012-07-02

    output,” Proc. SPIE 7914, 79140B, 79140B-8 (2011). 9. C. G. Carlson, R. B. Ross, J. M. Schafer, J. B. Spring, and B. G. Ward, “Full vectorial analysis...Stimulated Brillouin scattering (SBS) is a major factor limiting the output power of a fiber laser. In a lossless, passive fiber, SBS occurs when the product

  12. Distributed Strain Measurement along a Concrete Beam via Stimulated Brillouin Scattering in Optical Fibers

    Directory of Open Access Journals (Sweden)

    Romeo Bernini

    2011-01-01

    Full Text Available The structural strain measurement of tension and compression in a 4 m long concrete beam was demonstrated with a distributed fiber-optic sensor portable system based on Brillouin scattering. Strain measurements provided by the fiber-optic sensor permitted to detect the formation of a crack in the beam resulting from the external applied load. The sensor system is valuable for structural monitoring applications, enabling the long-term performance and health of structures to be efficiently monitored.

  13. TRUE COLORS: LEDS AND THE RELATIONSHIP BETWEEN CCT, CRI, OPTICAL SAFETY, MATERIAL DEGRADATION, AND PHOTOBIOLOGICAL STIMULATION

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.

    2014-08-30

    This document analyzes the optical, material, and photobiological hazards of LED light sources compared to conventional light sources. It documents that LEDs generally produce the same amount of blue light, which is the primary contributor to the risks, as other sources at the same CCT. Duv may have some effect on the amount of blue light, but CRI does not.

  14. Methods of Stimulating the Students' Creativity in the Study of Geometrical Optics

    Science.gov (United States)

    Florian, Gabriel; Trocaru, Sorin; Florian, Aurelia-Daniela; Bâna, Alexandru-Dumitru

    2015-01-01

    The aim of the present article is to focus on the operational aspects referring to the actions--strategies and on the defined modalities of establishing educational objectives/competences. In the achievement of our work a special attention has been paid to the operational aspects of the learning process of the optical phenomena. There were carried…

  15. A new sensitive system for measurement of thermally and optically stimulated luminescence

    DEFF Research Database (Denmark)

    Markey, B.G.; Bøtter-Jensen, L.; Poolton, N.R.J.

    1996-01-01

    optics of the system with a combination of ellipsoidal mirrors and light guides, which also serve to make the system more flexible in choice of excitation source when OSL measurements are required. A variety of new light sources might be employed, adapted to allow the most efficient wavelengths...

  16. Optic Nerve Stimulation System with Adaptive Wireless Powering and Data Telemetry

    Directory of Open Access Journals (Sweden)

    Xing Li

    2017-12-01

    Full Text Available To treat retinal degenerative diseases, a transcorneal electrical stimulation-based system is proposed, which consists of an eye implant and an external component. The eye implant is wirelessly powered and controlled by the external component to generate the required bi-polar current pattern for transcorneal stimulation with an amplitude range of 5 μA to 320 μA, a frequency range of 10 Hz to 160 Hz and a duty ratio range of 2.5% to 20%. Power delivery control includes power boosting in preparation for stimulation, and normal power regulation that adapts to both coupling and load variations. Only one pair of coils is used for both the power link and the bi-directional data link. Except for the secondary coil, the eye implant is fully integrated on chip and is fabricated using UMC (United Microelectronics Corporation, Hsinchu, Taiwan 0.13 μm complementary metal-oxide-semiconductor (CMOS process with a size of 1.5 mm × 1.5 mm. The secondary coil is fabricated on a printed circuit board (PCB with a diameter of only 4.4 mm. After coating with biocompatible silicone, the whole implant has dimensions of 6 mm in diameter with a thickness of less than 1 mm. The whole device can be put onto the sclera and beneath the eye’s conjunctiva. System functionality and electrical performance are demonstrated with measurement results.

  17. Ultrasound-Stimulated Mutual Interaction Forces between Optically Configured Micro-Bubble Pairs

    Science.gov (United States)

    Prentice, Paul A.; Campbell, Paul A.

    2007-05-01

    The mutual interaction between two oscillating encapsulated microbubbles was investigated using a novel optical trapping arrangement. This approach facilitated the development of an arbitrary, stable, initial spatial configuration for a two-bubble system. Critically, exercising optical control over such a binary bubble system meant that it could be isolated from the resident population of microbubbles during exposure to ultrasound. This ensured that any early stage dynamical evolution of the system was dominated by the mutual interaction of the two bubbles in view, rather than any extraneous influence arising from `crosstalk' with the rest of the bubble population. We observed, using high speed microphotography at 4×105 frames per second, that the action of secondary radiation forces leads to mutual bubble attraction. Phenomena such as coalescence and `bounce' were observed. Estimates of the microbubble [Sonovue™] compressibility could also be made, and tally well with published values obtained for other shelled contrast agents.

  18. Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation

    Science.gov (United States)

    Radhakrishnan, Harsha; Srinivasan, Vivek J.

    2013-08-01

    The hemodynamic response to neuronal activation is a well-studied phenomenon in the brain, due to the prevalence of functional magnetic resonance imaging. The retina represents an optically accessible platform for studying lamina-specific neurovascular coupling in the central nervous system; however, due to methodological limitations, this has been challenging to date. We demonstrate techniques for the imaging of visual stimulus-evoked hyperemia in the rat inner retina using Doppler optical coherence tomography (OCT) and OCT angiography. Volumetric imaging with three-dimensional motion correction, en face flow calculation, and normalization of dynamic signal to static signal are techniques that reduce spurious changes caused by motion. We anticipate that OCT imaging of retinal functional hyperemia may yield viable biomarkers in diseases, such as diabetic retinopathy, where the neurovascular unit may be impaired.

  19. Optically stimulated luminescence of Tb{sup 3+}/Sm{sup 3+} doubly doped K{sub 2}YF{sub 5} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, L.; Marcazzo, J.; Santiago, M.; Caselli, E. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Gral. Pinto 399, B7000GHG, Tandil (Argentina); Khaidukov, N. M., E-mail: jmarcass@exa.unicen.edu.ar [Kurnakov Institute of General and Inorganic Chemistry, RAS, Leninskii Prospekt 31, 119991 Moscow (Russian Federation)

    2014-08-15

    In this work optically stimulated luminescence (OSL) properties of K{sub 2}YF{sub 5} crystals doubly doped with Tb{sup 3+} and Sm{sup 3+} ions have been investigated for the first time. OSL responses for different dopant concentration and for optical stimulation with different wavelengths have been analyzed for each compound. Dosimetric properties of the most efficient composition, namely, K{sub 2}YF{sub 5}:1.0 at.% Tb{sup 3+}; 1.0 at.% Sm{sup 3+}, have been studied. Finally, the possible application of this single crystal as OSL dosimeter has been evaluated. (Author)

  20. An optically stimulated luminescence study of porcelain related to radiation dosimetry

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Jungner, H.

    1995-01-01

    Stokes and anti-Stokes shifted in energy. Glazing is shown in some cases to be considerably more sensitive as a radiation dosemeter than the main porcelain ceramic. By comparison with the properties of artifical phosphors, the principal luminescent matrix is identified as being Al2O3......This article describes the essential features regarding the photo-stimulated luminescence of porcelain: both the main ceramic and glazing materials are studied. In each case, radiation dose dependent signals are observed, superimposed on dose independent luminescence transitions that are both...

  1. An optically stimulated luminescence study of flint related to radiation dosimetry

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Rink, W.J.

    1995-01-01

    This article describes the essential features of photo-stimulated luminescence in flint. The emission is shown to be complex, arising from a number of different aspects of the material. Under constant illumination, dose-dependent time-decaying anti-Stokes signals are superimposed on dose......-independent, time-stable emission that is both Stokes and anti-Stokes shifted in energy. It is argued that the dose-dependent signals arise from the crystalline quartz phase of the material, whereas the dose independent signals originate from an amorphous-like phase of SiO2. The microcrystallinity of the material...

  2. Dosimetric methodology for extremities of individuals occupationally exposed to beta radiation using the optically stimulated luminescence technique

    International Nuclear Information System (INIS)

    Pinto, Teresa Cristina Nathan Outeiro

    2010-01-01

    A dosimetric methodology was established for the determination of extremity doses of individuals occupationally exposed to beta radiation, using Al 2 O 3 :C detectors and the optically stimulated luminescence (OSL) reader system microStar, Landauer. The main parts of the work were: characterization of the dosimetric material Al 2 O 3 :C using the OSL technique; establishment of the dose evaluation methodology; dose rate determination of beta radiation sources; application of the established method in a practical test with individuals occupationally exposed to beta radiation during a calibration simulation of clinical applicators; validation of the methodology by the comparison between the dose results of the practical test using the OSL and the thermoluminescence (TL) techniques. The results show that both the OSL Al-2O 3 :C detectors and the technique may be utilized for individual monitoring of extremities and beta radiation. (author)

  3. OPTICAL DATA PROCESSING: Realization of associative memory with the aid of a nonlinear selective stimulated-Brillouin-scattering mirror

    Science.gov (United States)

    Matveyev, A. Z.; Pasmanik, G. A.

    1993-05-01

    An associative memory using only optical elements has been realized experimentally. The key element of the arrangement is a stimulated-Brillouin-scattering (SBS) selector consisting of a short SBS medium at the focus of a lens. The qualitative advantage of the selector over an SBS mirror is demonstrated experimentally. The response time of the arrangement is ~ 10-8 s and is determined by the duration of the SBS. Estimates show that the SBS selector is capable in practice of distinguishing a signal against background noise when the initial distortion level of the object beam is 10-3. Reliable operation of the SBS selector has been demonstrated for radiative and energy loads reaching 2 GW/cm2 and 2 J, respectively.

  4. Dose response of commercially available optically stimulated luminescent detector, Al2O3:C for megavoltage photons and electrons.

    Science.gov (United States)

    Kim, Dong Wook; Chung, Weon Kuu; Shin, Dong Oh; Yoon, Myonggeun; Hwang, Ui-Jung; Rah, Jeong-Eun; Jeong, Hojin; Lee, Sang Yeob; Shin, Dongho; Lee, Se Byeong; Park, Sung Yong

    2012-04-01

    This study examined the dose response of an optically stimulated luminescence dosemeter (OSLD) to megavoltage photon and electron beams. A nanoDot™ dosemeter was used to measure the dose response of the OSLD. Photons of 6-15 MV and electrons of 9-20 MeV were delivered by a Varian 21iX machine (Varian Medical System, Inc. Milpitas, CA, USA). The energy dependency was dose was linear until 200 cGy. The superficial dose measurements revealed photon irradiation to have an angular dependency. The nanoDot™ dosemeter has potential use as an in vivo dosimetric tool that is independent of the energy, has dose linearity and a rapid response compared with normal in vivo dosimetric tools, such as thermoluminescence detectors. However, the OSLD must be treated very carefully due to the high angular dependency of the photon beam.

  5. Stimulated Brillouin scattering phase-locking using a transient acoustic standing wave excited through an optical interference field

    International Nuclear Information System (INIS)

    Ondrej Slezak; Milan Kalal; Hon Jin Kong

    2010-01-01

    Complete text of publication follows. Analytical description of an experimentally verified scheme leading to a phase-locked stimulated Brillouin scattering (SBS), used in a laser beam combination systems, is presented. The essential condition for the phase-locking effect for SBS is the fixation of the starting position and time of the acoustic Brillouin wave. It is shown that the starting position fixation of this acoustic wave may have its origin in a transient acoustic standing wave initiated by an arising optical interference field produced by the back-seeding concave mirror. This interference field leads to a stationary density modulation of the medium. However, the way to the formation of this density modulation leads via the acoustic standing wave. An appropriate solution, in the form of the standing wave, was obtained from solving the acoustic wave-equation using the electrostriction as a driving force. As a consequence of the damping term included in this equation the acoustic standing wave becomes gradually attenuated and contrary to the undamped solution published earlier, thus constitutes a truly transient phenomenon. Using a mathematical formalism similar to that which is used for the SBS description in the case of a random phase, the coupled equations describing the phase-locked SBS were derived. Contrary to the case without the back-seeding mirror, where the wave chosen from the thermal noise background subsequently plays the role of a trigger of the stimulated process, in this case it is replaced by the transient standing wave produced as a consequence of the presence of an optical interference field arisen in the focal region of the back-seeding concave mirror.

  6. Test-retest assessment of cortical activation induced by repetitive transcranial magnetic stimulation with brain atlas-guided optical topography

    Science.gov (United States)

    Tian, Fenghua; Kozel, F. Andrew; Yennu, Amarnath; Croarkin, Paul E.; McClintock, Shawn M.; Mapes, Kimberly S.; Husain, Mustafa M.; Liu, Hanli

    2012-11-01

    Repetitive transcranial magnetic stimulation (rTMS) is a technology that stimulates neurons with rapidly changing magnetic pulses with demonstrated therapeutic applications for various neuropsychiatric disorders. Functional near-infrared spectroscopy (fNIRS) is a suitable tool to assess rTMS-evoked brain responses without interference from the magnetic or electric fields generated by the TMS coil. We have previously reported a channel-wise study of combined rTMS/fNIRS on the motor and prefrontal cortices, showing a robust decrease of oxygenated hemoglobin concentration (Δ[HbO2]) at the sites of 1-Hz rTMS and the contralateral brain regions. However, the reliability of this putative clinical tool is unknown. In this study, we develop a rapid optical topography approach to spatially characterize the rTMS-evoked hemodynamic responses on a standard brain atlas. A hemispherical approximation of the brain is employed to convert the three-dimensional topography on the complex brain surface to a two-dimensional topography in the spherical coordinate system. The test-retest reliability of the combined rTMS/fNIRS is assessed using repeated measurements performed two to three days apart. The results demonstrate that the Δ[HbO2] amplitudes have moderate-to-high reliability at the group level; and the spatial patterns of the topographic images have high reproducibility in size and a moderate degree of overlap at the individual level.

  7. Collisional Dynamics, Lasing and Stimulated Raman Scattering in Optically Pumped Cesium and Potassium Vapors

    Science.gov (United States)

    2012-03-22

    system of rate equations with terms describing radiative rates, driving rates (form iΩjρij) and transition rates (form iωijρij) where the Ω are the Rabi ...longer than the cell. The flat high reflector and output coupler ( Lattice Electro Optics, Inc. ROC = 25 cm) form a stable 48 cm cavity. We tested...The potential terms in the Hamiltonian can be written using the Rabi frequency, Ωij = Eijµij h , and the frequency terms can be written as ∆nm = ωnm

  8. Sensory stimulation for lowering intraocular pressure, improving blood flow to the optic nerve and neuroprotection in primary open-angle glaucoma.

    Science.gov (United States)

    Rom, Edith

    2013-12-01

    Primary open-angle glaucoma is a group of optic neuropathies that can lead to irreversible blindness. Sensory stimulation in the form of acupuncture or ear acupressure may contribute to protecting patients from blindness when used as a complementary method to orthodox treatment in the form of drops, laser or surgery. The objective of this article is to provide a narrative overview of the available literature up to July 2012. It summarises reported evidence on the potential beneficial effects of sensory stimulation for glaucoma. Sensory stimulation appears to significantly enhance the pressure-lowering effect of orthodox treatments. Studies suggest that it may also improve blood flow to the eye and optic nerve head. Furthermore, it may play a role in neuroprotection through regulating nerve growth factor and brain-derived neurotrophic factor and their receptors, thereby encouraging the survival pathway in contrast to the pathway to apoptosis. Blood flow and neuroprotection are areas that are not directly influenced by orthodox treatment modalities. Numerous different treatment protocols were used to investigate the effect of sensory stimulation on intraocular pressure, blood flow or neuroprotection of the retina and optic nerve in the animal model and human pilot studies. Objective outcomes were reported to have been evaluated with Goldmann tonometry, Doppler ultrasound techniques and electrophysiology (pattern electroretinography, visually evoked potentials), and supported with histological studies in the animal model. Taken together, reported evidence from these studies strongly suggests that sensory stimulation is worthy of further research.

  9. Optically stimulated phosphorescence in quartz over the millisecond to second time scale: insights into the role of shallow traps in delaying luminescent recombination

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank

    2010-01-01

    -OSL and optically stimulated phosphorescence (OSP) covering over 8 orders of magnitude from 50 ns to ~8 s. A detailed characterization of the previously unstudied slowly decaying signals (millisecond–second time scales) is undertaken to understand the origin of these components and the role of re-trapping following...

  10. The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels

    Science.gov (United States)

    Khan, Muzafar; Heilemann, Gerd; Kuess, Peter; Georg, Dietmar; Berg, Andreas

    2018-03-01

    Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D), which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates. Some commonly used polymer gels are based on Methacrylic-Acid-Gel-Initiated-by-Copper (MAGIC). Here, we report on the dose sensitivity (ΔR2/ΔD) of MAGIC-type gels with different oxygen scavenger concentration for their specific dependence on the applied dose rate in order to improve the dosimetric performance, especially for high dose rates. A preclinical x-ray machine (‘Yxlon’, E  =  200 kV) was used for irradiation to cover a range of dose rates from low \\dot{D} min  =  0.6 Gy min-1 to high \\dot{D} max  =  18 Gy min-1. The dose response was evaluated using R2-imaging of the gel on a human high-field (7T) MR-scanner. The results indicate that all of the investigated dose rates had an impact on the dose response in polymer gel dosimeters, being strongest in the high dose region and less effective for low dose levels. The absolute dose rate dependence \\frac{(Δ R2/Δ D)}{Δ \\dot{D}} of the dose response in MAGIC-type gel is significantly reduced using higher concentrations of oxygen scavenger at the expense of reduced dose sensitivity. For quantitative dose evaluations the relative dose rate dependence of a polymer gel, normalized to its sensitivity is important. Based on this normalized sensitivity the dose rate sensitivity was reduced distinctly

  11. The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels.

    Science.gov (United States)

    Khan, Muzafar; Heilemann, Gerd; Kuess, Peter; Georg, Dietmar; Berg, Andreas

    2018-03-12

    Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2 (D) , which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates. Some commonly used polymer gels are based on Methacrylic-Acid-Gel-Initiated-by-Copper (MAGIC). Here, we report on the dose sensitivity (ΔR2/ΔD) of MAGIC-type gels with different oxygen scavenger concentration for their specific dependence on the applied dose rate in order to improve the dosimetric performance, especially for high dose rates. A preclinical x-ray machine ('Yxlon', E  =  200 kV) was used for irradiation to cover a range of dose rates from low [Formula: see text] min   =  0.6 Gy min -1 to high [Formula: see text] max   =  18 Gy min -1 . The dose response was evaluated using R2-imaging of the gel on a human high-field (7T) MR-scanner. The results indicate that all of the investigated dose rates had an impact on the dose response in polymer gel dosimeters, being strongest in the high dose region and less effective for low dose levels. The absolute dose rate dependence [Formula: see text] of the dose response in MAGIC-type gel is significantly reduced using higher concentrations of oxygen scavenger at the expense of reduced dose sensitivity. For quantitative dose evaluations the relative dose rate dependence of a polymer gel, normalized to its sensitivity is important. Based on this normalized sensitivity the dose rate sensitivity was reduced

  12. Development of optically stimulated luminescence techniques using natural minerals and ceramics, and their application to retrospective dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Boetter-Jensen, L

    2000-09-01

    This thesis summarises research and development of optically stimulated luminescence (OSL) and its applications by the author at Risoe National Laboratory, up to 1999. These developments have been directed primarily at retrospective accident dosimetry and luminescence dating. Experimental investigations include the studies of OSL properties of the natural minerals quartz and feldspars and the artificial materials porcelain and aluminium oxide (Al{sub 2}O{sub 3}). Blue light emitting diodes and infrared laser diodes are shown to provide simple and practical alternatives to broad-band light and visible laser stimulation. The development of OSL apparatus designed for the rapid measurement of single grains of phosphors also opens up a new area of luminescence measurement, allowing the detailed examination of dose distributions within a multiple-grain sample. This is of particular importance to the studies of incompletely reset geological sediments, and to accident dosimetry measurements using unheated materials. Al{sub 2}O{sub 3}:C single crystals are tested as environmental OSL dosemeters for assessing both the natural background photon radiation dose rates in the field and the natural dose rates inside bricks collected for accident dose evaluation. Environmental doses of the order of few {mu}Gy are measured with high precision. UV photo-stimulated luminescence spectra obtained from porcelain samples are used to confirm that the main component responsible for the OSL signal from porcelain is Al{sub 2}O{sub 3}. OSL single-aliquot regenerative-dose (SAR) techniques are used with quartz extracted from Chernobyl bricks to determine the accrued dose after the accident. This has improved the measurement precision significantly, from about 5-6 % using traditional methods to now less than 2 %. Depth-dose profiles measured in Chernobyl bricks are compared with those obtained in the laboratory using different gamma sources and these comparisons show that the average energy of

  13. Development of optically stimulated luminescence techniques using natural minerals and ceramics, and their application to retrospective dosimetry

    International Nuclear Information System (INIS)

    Boetter-Jensen, L.

    2000-09-01

    This thesis summarises research and development of optically stimulated luminescence (OSL) and its applications by the author at Risoe National Laboratory, up to 1999. These developments have been directed primarily at retrospective accident dosimetry and luminescence dating. Experimental investigations include the studies of OSL properties of the natural minerals quartz and feldspars and the artificial materials porcelain and aluminium oxide (Al 2 O 3 ). Blue light emitting diodes and infrared laser diodes are shown to provide simple and practical alternatives to broad-band light and visible laser stimulation. The development of OSL apparatus designed for the rapid measurement of single grains of phosphors also opens up a new area of luminescence measurement, allowing the detailed examination of dose distributions within a multiple-grain sample. This is of particular importance to the studies of incompletely reset geological sediments, and to accident dosimetry measurements using unheated materials. Al 2 O 3 :C single crystals are tested as environmental OSL dosemeters for assessing both the natural background photon radiation dose rates in the field and the natural dose rates inside bricks collected for accident dose evaluation. Environmental doses of the order of few μGy are measured with high precision. UV photo-stimulated luminescence spectra obtained from porcelain samples are used to confirm that the main component responsible for the OSL signal from porcelain is Al 2 O 3 . OSL single-aliquot regenerative-dose (SAR) techniques are used with quartz extracted from Chernobyl bricks to determine the accrued dose after the accident. This has improved the measurement precision significantly, from about 5-6 % using traditional methods to now less than 2 %. Depth-dose profiles measured in Chernobyl bricks are compared with those obtained in the laboratory using different gamma sources and these comparisons show that the average energy of the accident radiation was

  14. Sci—Fri PM: Topics — 06: The influence of regional dose sensitivity on salivary loss and recovery in the parotid gland

    Energy Technology Data Exchange (ETDEWEB)

    Clark, H [University of British Columbia, Vancouver, B.C. (Canada); BC Cancer Agency, Surrey, B.C. (Canada); BC Cancer Agency, Vancouver, B.C. (Canada); Thomas, S [BC Cancer Agency, Surrey, B.C. (Canada); Moiseenko, V [University of California San Diego, La Jolla, Ca (United States); Hovan, A; Wu, J [BC Cancer Agency, Vancouver, B.C. (Canada)

    2014-08-15

    Purpose: The Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC 2010) survey of radiation dose-volume effects on salivary gland function has called for improved understanding of intragland dose sensitivity and the effectiveness of partial sparing in salivary glands. Regional dose susceptibility of sagittally- and coronally-sub-segmented parotid gland has been studied. Specifically, we examine whether individual consideration of sub-segments leads to improved prediction of xerostomia compared with whole parotid mean dose. Methods: Data from 102 patients treated for head-and-neck cancers at the BC Cancer Agency were used in this study. Whole mouth stimulated saliva was collected before (baseline), three months, and one year after cessation of radiotherapy. Organ volumes were contoured using treatment planning CT images and sub-segmented into regional portions. Both non-parametric (local regression) and parametric (mean dose exponential fitting) methods were employed. A bootstrap technique was used for reliability estimation and cross-comparison. Results: Salivary loss is described well using non-parametric and mean dose models. Parametric fits suggest a significant distinction in dose response between medial-lateral and anterior-posterior aspects of the parotid (p<0.01). Least-squares and least-median squares estimates differ significantly (p<0.00001), indicating fits may be skewed by noise or outliers. Salivary recovery exhibits a weakly arched dose response: the highest recovery is seen at intermediate doses. Conclusions: Salivary function loss is strongly dose dependent. In contrast no useful dose dependence was observed for function recovery. Regional dose dependence was observed, but may have resulted from a bias in dose distributions.

  15. Evaluation of personal dose equivalent using optically stimulated luminescent dosemeters in Marumori after the Fukushima nuclear accident

    International Nuclear Information System (INIS)

    Yoshida-Ohuchi, H.; Hirasawa, N.; Kobayashi, I.; Yoshizawa, T.

    2013-01-01

    The personal dose equivalent for 36 Marumori residents living in wooden houses was evaluated using optically stimulated luminescent dosemeters after the Fukushima nuclear accident. The cumulative doses to residents over 200 d from 1 September 2011 ranged from 536 to 1490 μSv. In each resident's house, the indoor and outdoor ambient dose equivalents were measured with an NaI scintillation survey meter. A linear relationship with a slope of 0.5 was found between them; however, the ratio of the indoor to the outdoor ambient dose equivalent varied from 0.36 to 1.0. A better linear relationship was observed between the personal dose equivalent and the indoor ambient dose equivalent compared with that between the personal dose equivalent and the outdoor ambient dose equivalent. These results indicate that the individual exposure dose depends on the indoor ambient dose equivalent rather than the outdoor ambient dose equivalent. These results should be very helpful in obtaining the countermeasures to reduce residents' exposure dose. (authors)

  16. Radiation dose measurements of an on-board imager X-ray unit using optically-stimulated luminescence dosimeters

    International Nuclear Information System (INIS)

    Smith, Leon; Haque, Mamoon; Hill, Robin; Morales, Johnny

    2015-01-01

    Cone beam computed tomography (CBCT) is now widely used to image radiotherapy patients prior to treatment for the purpose of accurate patient setup. However each CBCT image delivered to a patient increases the total radiation dose that they receive. The measurement of the dose delivered from the CBCT images is not readily performed in the clinic. In this study, we have used commercially available optically stimulated luminescence (OSLD) dosimeters to measure the dose delivered by the Varian OBI on a radiotherapy linear accelerator. Calibration of the OSLDs was achieved by using a therapeutic X-ray unit. The dose delivered by a head CBCT scan was found to be 3.2 ± 0.3 mGy which is similar in magnitude to the dose of a head computed tomography (CT) scan. The results of this study suggest that the radiation hazard associated with CBCT is of a similar nature to that of conventional CT scans. We have also demonstrated that the OSLDs are suitable for these low X-ray dose measurements.

  17. Detection of herbs and spices irradiated through optically stimulated luminescence; Deteccion de hierbas y especias irradiadas mediante luminiscencia opticamente estimulada

    Energy Technology Data Exchange (ETDEWEB)

    Preciado, S.; Agundez A, Z.; Barboza F, M. [Centro de Investigacion en Fisica, Universidad de Sonora, A.P. 5-088, 83190 Hermosillo, Sonora (Mexico); Cruz Z, E. [Instituto de Ciencias Nucleares de la UNAM, 04510 Mexico D.F. (Mexico)

    2003-07-01

    The irradiation of foods is one of the common practices in several countries of the American and European continents. In spite of the widespread use of irradiation methods and technics of nutritious products, it doesn't exist a method of general use at the present time for the detection of previously submitted foods to irradiation with pasteurization ends or sterilization. In the present work the results are presented obtained in the detection of herbs and spices exposed to radiation in the range of 0.1 - 3 KGy, by means of the photostimulation with light of 470 nm. It was used for it a RIS0 model team TL/OSL-GIVE-15 conditioned with a {beta} ray source, {sup 90}Sr/{sup 90}Y and a source of light of 50 mW/cm2. samples of chili guajillo were studied, pepper, cumin, mint and camomile; achieving you to detect exhibitions of the order of 8.33x10{sup -4} KGy that which is indicative of the high sensitivity of the luminescence technique optically stimulated. The answer of the samples with regard to the radiation dose presents a range of lineality for low dose of the order of 0.5 KGy; and supralineal for further dose without to arrive to a saturation stage. (Author)

  18. Thermally and optically stimulated radiative processes in Eu and Y co-doped LiCaAlF{sub 6} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Kentaro, E-mail: ken-fukuda@tokuyama.co.jp [Tokuyama Corporation, 1-1 Mikage-cho, Shunan-shi, Yamaguchi 745-8648 (Japan); Yanagida, Takayuki; Fujimoto, Yutaka [Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu, Kitakyushu, Fukuoka 808-0196 (Japan)

    2015-06-01

    Yttrium co-doping was attempted to enhance dosimeter performance of Eu doped LiCaAlF{sub 6} crystal. Eu doped and Eu, Y co-doped LiCaAlF{sub 6} were prepared by the micro-pulling-down technique, and their dosimeter characteristics such as optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) were investigated. By yttrium co-doping, emission intensities of OSL and TSL were enhanced by some orders of magnitude. In contrast, scintillation characteristics of yttrium co-doped crystal such as intensity of prompt luminescence induced by X-ray and light yield under neutron irradiation were degraded.

  19. Measurements of stimulated-Raman-scattering-induced tilt in spectral-amplitude-coding optical code-division multiple-access systems

    Science.gov (United States)

    Al-Qazwini, Zaineb A. T.; Abdullah, Mohamad K.; Mokhtar, Makhfudzah B.

    2009-01-01

    We measure the stimulated Raman scattering (SRS)-induced tilt in spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) systems as a function of system main parameters (transmission distance, power per chip, and number of users) via computer simulations. The results show that SRS-induced tilt significantly increases as transmission distance, power per chip, or number of users grows.

  20. Optically stimulated luminescence and isothermal thermoluminescence dating of high sensitivity and well bleached quartz from Brazilian sediments: from Late Holocene to beyond the Quaternary?

    OpenAIRE

    Sawakuchi, André Oliveira; Mendes, Vinicius Ribau; Pupim, Fabiano do Nascimento; Mineli, Thays Desiree; Ribeiro, Ligia Maria Almeida Leite; Zular, Andre; Guedes, Carlos Conforti Ferreira; Giannini, Paulo César Fonseca; Nogueira, Luciana; Sallun Filho, William; Assine, Mario Luis

    2016-01-01

    ABSTRACT: The development of optically stimulated luminescence (OSL) dating of sediments has led to considerable advance in the geochronology of the Quaternary. OSL dating is a well established technique to determine sediment burial ages from tens of years to few hundred thousand years. Recent studies have shown that Quaternary sediments of Brazil are dominated by quartz grains with high luminescence sensitivity, allowing the determination of precise and reliable OSL burial ages. In this pape...

  1. Quantitative evaluation of mineral grains using automated SEM–EDS analysis and its application potential in optically stimulated luminescence dating

    International Nuclear Information System (INIS)

    Meyer, Michael C.; Austin, Peter; Tropper, Peter

    2013-01-01

    Optically stimulated luminescence (OSL) dating allows constraining the depositional age of sediments with good accuracy and precision. A fundamental requirement in OSL dating is to use purified sub-samples (i.e. mono-mineralogic aliquots composed of e.g. quartz or potassium feldspar only), because of the different OSL properties and dosimetry characteristics of each mineral phase. Where multiple mineral phases are present on an aliquot, a mixed OSL signal might be obtained, with potentially adverse effects on the robustness of the resulting optical ages. Detailed evaluation of the mineralogical composition of the hundreds or even thousands of individual mineral particles that constitute an aliquot in OSL dating has – until recently – not been reasonably feasible with current analytical techniques. Here we report on the use of an automated mineralogy system that combines scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and facilitates ultra-fast analysis of particulate mineral phases with a spatial resolution on the micron scale. The method is applied to mono-mineralogic coarse-grained (100–250 μm) and poly-mineral fine-grained (4–11 μm) OSL samples, respectively and cross-checked with electron probe micro analysis (EPMA). It is shown that (i) some coarse-grained mineral extracts that underwent standard physico-chemical preparation to isolate quartz for OSL dating, still suffer from mineralogical contamination, mainly in the form of feldspar and mica inclusions and, that (ii) polymineral fine-grained samples reveal a complex mineralogical composition with a significant percentage of mica (mainly muscovite). Implications of these quantitative mineralogical observations for OSL dating are discussed. QEMSCAN is further used to examine the efficiency of different physico-chemical preparation strategies to isolate a restricted range of mineralogies and to optimize single preparation steps. We conclude that the clear advantage of

  2. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy.

    Directory of Open Access Journals (Sweden)

    Hiroaki Hasegawa

    Full Text Available The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT fluoroscopy using the integrated dose ratio (IDR of an X-ray dose profile derived from an optically stimulated luminescent (OSL dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (-50 to -6 mm, 50 to 6 mm was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies.

  3. Converting a major dosimetry service from film to optically stimulated luminescence dosemeters including revision of the 'back-office' software

    International Nuclear Information System (INIS)

    Perks, Christopher A.; Faugoin, Stephane; Serise, Bertrand; Prugnaud, Brice; Million, Marc

    2008-01-01

    Full text: In our offices at Fontenay-aux-Roses we provide personal dosimetry for over 100,000 participants. During 2005/6 we transformed our operations from film dosemeters to those using Optically Stimulated Luminescence (InLight (Trade Mark)). The opportunity was taken to fully overhaul our operational procedures and we are currently completely reworking our 'back-office' software support. The change from film to InLight dosimetry has involved: 1) The installation of new readers at our offices in Fontenay-aux Roses; 2) The installation of a physical badge archiving system; 3) Complete revision of the operational flow to optimise the benefits of the new service; 4) Maintenance of our approval to operate a personal dosimetry service in France; 5) Considerable liaison between our office in Fontenay-aux-Roses and our Glenwood, USA, parent company to enable complete integration of the processes; and 6) Maintaining the service throughout the changeover and keeping client satisfaction high. Having changed the physical environment we are now completely renewing the back office software and systems in support of the dosimetry service. This ranges in scope from entering new clients, client support, all aspects of the dosimetry operations and chain of custody of the dosemeters and participants records and reports. This system is being rolled out in sections and it is envisaged that it will be fully implemented at the start of 2008. A key feature is that continuing improvement and the possibility of future developments of our services is in-built into the philosophy of the new back-office system. The nature of the new system, its benefits to our own operations and, in particular, clients will be discussed. (author)

  4. Study of optically stimulated luminescence (OSL) for radiation detection. Application to an optical fibre {gamma}-radiation sensor; Etude de la luminescence stimulee optiquement (OSL) pour la detection de rayonnements: application a un capteur a fibre optique de rayonnement {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Roy, O. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Electronique et d`Instrumentation Nucleaire]|[Paris-7 Univ., 75 (France)

    1998-12-31

    This work shows up the usefulness of the Optically Stimulated Luminescence (OSL) to resolve radioprotection problems. We study the use of OSL as a gamma dosimetric technique with respect to the ALARA`s concept (As Low As Reasonably Achievable). A new approach based on optical fibers and luminescent materials showing OSL properties (closely related to Thermoluminescence phenomena) is presented in order to improve the remote real time dosimetry monitoring. Like thermoluminescent materials (TLD), OSL materials can trap charges under an irradiation (UV, X, {gamma},...). Instead of heating, the charges trapped are released by light stimulation and produce a visible luminescence which amount is proportional to trap the `data stored` left by irradiation, enabling the dose measurement. The OSL phenomenon offers the same advantages as TLD plus the interesting possibility of a remote optical stimulation. The end-user objective deals with the development of a {gamma}-radiation Optical FIber Sensor (OFS) for dose measurement which can offer new functionalities based on OSL materials coupled with an optical fiber. Rare earth doped Alkaline Earth Sulphides (AES), BAFX:EU{sup 2+} (X = Cl, Br, I) and halogen alkaline have been studied (crystalline form, synthesis techniques, influence of dopants and color centers). Their characteristics are presented and extensively discussed. A specific experimental set-up to characterise various OSL phosphors has been developed. It allows the study of sensitivity, linearity, time decay behaviour of OSL signal and zeroing time. A joint study of OSL and TL has shown the technical limitations as well as the thermal fading and the origin of the long zeroing time. An Optical Fiber Sensor (OFS) based on OSL and using MgS:Sm has been developed for practical applications on nuclear fields. Its specifications are presented and discussed, moreover improvements are proposed. (author) 320 refs.

  5. Thermoluminescence, luminescence optically stimulated and creation of defects in alkaline halogenides contaminated with Europium; Termoluminiscencia, luminiscencia opticamente estimulada y creacion de defectos en halogenuros alcalinos contaminados con Europio

    Energy Technology Data Exchange (ETDEWEB)

    Barboza F, M. [Centro de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, 83190 Hermosillo, Sonora (Mexico)

    1999-07-01

    The alkaline halogenides have been subject matter of investigations related with the search of sensor materials for X-ray bidimensional images or optical memories. The understanding of the damage formation processes generated by ionizing and non-ionizing radiations is important for the correct design of devices that working as detectors and dosemeters of both type of radiations. In this work we present the investigation results related with the defects produced by the ionizing radiation type X and ultraviolet light in the range of 200-360 nm in crystals of KCl: Eu{sup 2+} and KBr:Eu{sup 2+}. It is examined the thermoluminescence and luminescence spectra with the purpose of identifying the exciton processes, owing to the excitation of the halogenide ions in which the primary defects correspond to the F and H centers. It has been found that the 400-600 nm emission is associated with the luminescence type that in his turn can be associated with autotrapped excitons perturbed by the impurity. On the other hand, it is examined the emission spectra of the luminescence optically stimulated in crystals of KBr: Eu{sup 2+} and KCl: Eu{sup 2+} finding too that such materials would be used as optical memories susceptible of to store information, and through of photostimulation to read this. It was determined that the F centers participate in the luminescence optically stimulated in these crystals, as well as too in the recombination processes responsible by the thermoluminescent emission. (Author)

  6. Optics

    CERN Document Server

    Mathieu, Jean Paul

    1975-01-01

    Optics, Parts 1 and 2 covers electromagnetic optics and quantum optics. The first part of the book examines the various of the important properties common to all electromagnetic radiation. This part also studies electromagnetic waves; electromagnetic optics of transparent isotropic and anisotropic media; diffraction; and two-wave and multi-wave interference. The polarization states of light, the velocity of light, and the special theory of relativity are also examined in this part. The second part is devoted to quantum optics, specifically discussing the classical molecular theory of optical p

  7. Somatotopic Organization and Temporal Characteristics of Cerebrocortical Excitation in Response to Nasal Mucosa Stimulation With and Without an Odor in the Rat: An Optical Imaging Study.

    Science.gov (United States)

    Zama, Manabu; Hara, Yaeko; Fujita, Satoshi; Kaneko, Tadayoshi; Kobayashi, Masayuki

    2018-05-01

    Nasal mucosa has roles in warming and humidifying inspired air and is highly sensitive to mechanical stimuli. Moreover, the upper part of the nasal mucosa expresses olfactory receptors processing olfactory information. Although the somatosensory map of the face in the primary (S1) and secondary (S2) somatosensory cortices is clearly documented, the map of the nasal mucosa and the effect of odors on their activities are largely unknown. This study aimed to identify the cortical regions in S1 and their temporal features in response to somatosensory stimulation of the nasal mucosa using an optical imaging technique in urethane-anesthetized rats. An air puff application response to nasal mucosa first occurred in a part of contralateral S1 and subsequently, spread toward the rostrally and ventrally adjacent sites. Upper pharynx stimulation initially activated this rostrally expanded site and the excitatory propagation from the initially activated region toward ventral region likely represented S2. Signal intensity and activated area increased dependent on air pressure. Nasal tip stimulation initially excited S1 region caudally adjacent to that of nasal mucosa. Moreover, the amplitude of S1 excitation was similar between air puff stimulation with and without an odor, amyl acetate. In contrast to contralateral S1, air puff stimulation with the odor showed a faint optical signal increase in the ipsilateral piriform cortex. These results suggest that somatosensory information from the nasal mucosa and skin, and upper pharynx are processed in spatially continuous regions of S1, and interaction between somatosensory and olfactory systems is relatively small in contralateral S1. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Comparison of Cottonwood Dendrochronology and Optically Stimulated Luminescence Geochronometers Along a High Plains Meandering River, Powder River, Montana, USA

    Science.gov (United States)

    Hasse, T. R.; Schook, D. M.

    2017-12-01

    Geochronometers at centennial scales can aid our understanding of process rates in fluvial geomorphology. Plains cottonwood trees (Populus deltoides ssp. Monilifera) in the high plains of the United States are known to germinate on freshly created deposits such as point bars adjacent to rivers. As the trees mature they may be partially buried (up to a few meters) by additional flood deposits. Cottonwood age gives a minimum age estimate of the stratigraphic surface where the tree germinated and a maximum age estimate for overlying sediments, providing quantitative data on rates of river migration and sediment accumulation. Optically Stimulated Luminescence (OSL) of sand grains can be used to estimate the time since the sand grains were last exposed to sunlight, also giving a minimum age estimate of sediment burial. Both methods have disadvantages: Browsing, partial burial, and other damage to young cottonwoods can increase the time required for the tree to reach a height where it can be sampled with a tree corer, making the germination point a few years to a few decades older than the measured tree age; fluvial OSL samples can have inherited age (when the OSL age is older than the burial age) if the sediment was not completely bleached prior to burial. We collected OSL samples at 8 eroding banks of the Powder River Montana, and tree cores at breast height (±1.2 m) from cottonwood trees growing on the floodplain adjacent to the OSL sample locations. Using the Minimum Age Model (MAM) we found that OSL ages appear to be 500 to 1,000 years older than the adjacent cottonwood trees which range in age (at breast height) from 60 to 185 years. Three explanations for this apparent anomaly in ages are explored. Samples for OSL could be below a stratigraphic unconformity relative to the cottonwood germination elevation. Shallow samples for OSL could be affected by anthropogenic mixing of sediments due to plowing and leveling of hay fields. The OSL samples could have

  9. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  10. Implementation of Optical Meanders of the Optical-Fiber DTS System Based on Raman Stimulated Scattering into the Building Processes

    Directory of Open Access Journals (Sweden)

    Petr Koudelka

    2012-01-01

    Full Text Available The Optical fiber DTS (Distribution Temperature Systems are unique distributed temperature systems using optical fiber as a sensor. These systems are able to measure the temperature along the fiber, in some case they can measure tension as well. For their function they use nonlinear effect in optical fiber (Raman nonlinear effect, Brillouin nonlinear effect. The greatest advantage of this sensor system is just using of the optical fiber (electromagnetic resistance, small size, safety using in inflammable and explosive area, easy installation, etc.. The Optical fiber DTS systems can be used with advantage even in areas, where the using of classic sensors would be problematic. The typical example is monitoring of outflows in pipelines, illegal service connection etc. In some processes it is necessary to know exact temperature (tension in particular points. There it can appear a problem with resolution of the optical-fiber DTS. This article deals with problems of the optical meanders implementation into the building processes.

  11. Optically stimulated luminescence in x-ray irradiated xSnO-(25-x)SrO-75B2O3 glass

    Science.gov (United States)

    Nanto, H.; Nakagawa, R.; Takei, Y.; Hirasawa, K.; Miyamoto, Y.; Masai, H.; Kurobori, T.; Yanagida, T.; Fujimoto, Y.

    2015-06-01

    An intense optically stimulated luminescence (OSL) was observed, for the first time, in x-ray irradiated xSnO-(25-x)SrO-75B2O3 glass. It was found that the peak wavelength of OSL emission spectrum and its stimulation spectrum is about 400 nm and 600 nm, respectively. The OSL intensity is depended on the SnO contents (x=0.05-1.5) and the most intense OSL was observed in 1.0 mol% SnO doped glass. It was found that the OSL intensity is increased with increasing x-ray absorbed dose. Fairly good fading characteristics were observed in the x-ray irradiated glass, showing that this glass is useful as a candidate for OSL sensor materials for ionizing radiation monitoring.

  12. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  13. The origin of dose distributions in fluvial sediments, and the prospect of dating single grains from fluvial deposits using optically stimulated luminescence

    International Nuclear Information System (INIS)

    Olley, J.M.; Caitcheon, G.G.; Roberts, R.G.

    1999-01-01

    We examine the causes of the asymmetric distributions of dose observed from measurements of the optically stimulated luminescence emitted by small aliquots of fluvial quartz, and deduce that the asymmetry arises as a result of samples being composed of a mix of mainly well bleached grains with grains that were effectively unbleached at the time of deposition. We demonstrate that the shapes of the dose distributions can be used to assess the likelihood that aliquots consist only of grains that were well-bleached at the time of deposition. The more asymmetric the distribution, the greater the probability that the aliquots with the lowest dose most closely represent the true burial dose. Single grains with differing doses are present in each of the samples examined, and the population with the lowest dose gives an optical age consistent with the expected burial age. This result implies that the beta-dose heterogeneity in these deposits is small, and that the effects of micro-dosimetric variations on optical dating of individual grains are not significant for these samples. We demonstrate that single-grain dating of fluvial material is possible and practicable using standard Risoe optical dating equipment, and we conclude that application of a new regenerative-dose protocol to single grains of quartz, using the lowest dose population to estimate the burial dose, is the best available means of obtaining reliable luminescence ages for heterogeneously bleached fluvial sediments

  14. The origin of dose distributions in fluvial sediments, and the prospect of dating single grains from fluvial deposits using optically stimulated luminescence

    CERN Document Server

    Olley, J M; Roberts, R G

    1999-01-01

    We examine the causes of the asymmetric distributions of dose observed from measurements of the optically stimulated luminescence emitted by small aliquots of fluvial quartz, and deduce that the asymmetry arises as a result of samples being composed of a mix of mainly well bleached grains with grains that were effectively unbleached at the time of deposition. We demonstrate that the shapes of the dose distributions can be used to assess the likelihood that aliquots consist only of grains that were well-bleached at the time of deposition. The more asymmetric the distribution, the greater the probability that the aliquots with the lowest dose most closely represent the true burial dose. Single grains with differing doses are present in each of the samples examined, and the population with the lowest dose gives an optical age consistent with the expected burial age. This result implies that the beta-dose heterogeneity in these deposits is small, and that the effects of micro-dosimetric variations on optical dati...

  15. Simultaneous intracavity optical parametric oscillation and stimulated Raman scattering pumped by a doubly passively Q-switched Nd:GGG laser

    Science.gov (United States)

    Chu, Hongwei; Zhao, Jia; Li, Yufei; Zhao, Shengzhi; Yang, Kejian; Li, Dechun; Li, Guiqiu; Li, Tao; Qiao, Wenchao

    2014-12-01

    By using a doubly passively Q-switched Nd:Gd3Ga5O12(Nd:GGG) laser with Cr4+:YAG and GaAs as saturable absorbers as pump laser, simultaneous intracavity optical parametric oscillation and stimulated Raman scattering based on a single X-cut KTiOPO4 (KTP) crystal have been realized. Under an incident diode pump power of 10.5 W, the output powers at the signal wave near 1,569 nm and the first Stokes emission near 1,094 nm were 218 and 72 mW, corresponding to the optical-to-optical conversion efficiencies of 2.08 and 0.69 %, respectively. The measured shortest pulse duration at the signal wave near 1,569 nm was 580 ps, generating a pulse peak power of 43.7 kW, while the minimum pulse duration at the first Stokes emission near 1,094 nm was 1.61 ns. By adjusting the tilt angle of the KTP crystal, up to the third Stokes scattering was also obtained.

  16. Optically stimulated luminescence of ZnO obtained by thermal treatment of ZnS chemically synthesized; Luminiscencia opticamente estimulada de ZnO obtenido por tratamiento termico de ZnS sintetizado quimicamente

    Energy Technology Data Exchange (ETDEWEB)

    Cruz V, C.; Burruel I, S.E.; Orante B, V.R.; Grijalva M, H.; Perez S, R.; Bernal, R. [Universidad de Sonora, A.P. 130, Hermosillo (Mexico)

    2005-07-01

    In this work, we report the optically stimulated luminescence (OSL) dosimetry of new nano phosphors of ZnO obtained by thermal annealing of chemically synthesized ZnS powder. The synthesized ZnS nano powder was compressed in order to form pellet shaped pellets, which were afterwards subjected to a thermal annealing at 700 C during 24 h under air atmosphere. X-ray diffraction (XRD) patterns and energy-disperse X-ray Spectrometry (EDS) analyses confirmed the transformation of ZnS to ZnO. Samples were exposed to several doses of beta radiation up to 600 Gy, and the optically stimulated luminescence with 470 nm wavelength light was recorded as a function of dose. The intensity of the OSL signal increases by increasing dose, for what it is concluded that these new phosphor materials are suitable to be used in optically stimulated luminescence dosimetry. (Author)

  17. OptoZIF Drive: a 3D printed implant and assembly tool package for neural recording and optical stimulation in freely moving mice

    Science.gov (United States)

    Freedman, David S.; Schroeder, Joseph B.; Telian, Gregory I.; Zhang, Zhengyang; Sunil, Smrithi; Ritt, Jason T.

    2016-12-01

    Objective. Behavioral neuroscience studies in freely moving rodents require small, light-weight implants to facilitate neural recording and stimulation. Our goal was to develop an integrated package of 3D printed parts and assembly aids for labs to rapidly fabricate, with minimal training, an implant that combines individually positionable microelectrodes, an optical fiber, zero insertion force (ZIF-clip) headstage connection, and secondary recording electrodes, e.g. for electromyography (EMG). Approach. Starting from previous implant designs that position recording electrodes using a control screw, we developed an implant where the main drive body, protective shell, and non-metal components of the microdrives are 3D printed in parallel. We compared alternative shapes and orientations of circuit boards for electrode connection to the headstage, in terms of their size, weight, and ease of wire insertion. We iteratively refined assembly methods, and integrated additional assembly aids into the 3D printed casing. Main results. We demonstrate the effectiveness of the OptoZIF Drive by performing real time optogenetic feedback in behaving mice. A novel feature of the OptoZIF Drive is its vertical circuit board, which facilities direct ZIF-clip connection. This feature requires angled insertion of an optical fiber that still can exit the drive from the center of a ring of recording electrodes. We designed an innovative 2-part protective shell that can be installed during the implant surgery to facilitate making additional connections to the circuit board. We use this feature to show that facial EMG in mice can be used as a control signal to lock stimulation to the animal’s motion, with stable EMG signal over several months. To decrease assembly time, reduce assembly errors, and improve repeatability, we fabricate assembly aids including a drive holder, a drill guide, an implant fixture for microelectode ‘pinning’, and a gold plating fixture. Significance. The

  18. Energy levels in YPO{sub 4}:Ce{sup 3+},Sm{sup 3+} studied by thermally and optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Bos, Adrie J.J., E-mail: a.j.j.bos@tudelft.n [Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands); Poolton, Nigel R.J. [Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands); Institute of Maths and Physics, Aberystwyth University, Aberystwyth SY23 3BZ (United Kingdom); Wallinga, Jakob [Netherlands Centre for Luminescence Dating, Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands); Bessiere, Aurelie [Ecole Nat. Superieure de Chimie de Paris, 11 Rue P et M Curie, 75231 Paris Cedex 05 (France); Dorenbos, Pieter [Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands)

    2010-03-15

    Energy-resolved optically stimulated luminescence (OSL) spectra and thermoluminescence (TL) glow curves of a powder sample of YPO{sub 4}:Ce{sup 3+},Sm{sup 3+} were measured to investigate the nature of the trapping centre and to locate its energy level relative to the valence and conduction bands of the YPO{sub 4} host. The high-temperature glow peak could unequivocally be assigned to Sm{sup 2+} (thus Sm{sup 3+} acts as an electron trap). The trap depth of this centre, as derived from the OSL excitation spectra, is in good agreement with the Dorenbos model prediction. The OSL excitation spectra also reveal excited states of Sm{sup 2+} well below the conduction band. These excited states produce a broadening of the high-temperature TL glow peak and also cause the activation energy determined by the Hoogenstraten method to underestimate the trap depth.

  19. Photic stimulation of the suprachiasmatic nucleus via the non-visual optic system. A gene expression study in the blind Crx (-/-) mouse

    DEFF Research Database (Denmark)

    Rovsing, Louise; Møller, Morten

    2014-01-01

    photoreceptors. At zeitgeber time 16, the Crx (-/-) and wild-type mice were exposed to 1 h of light. This resulted in a strong up-regulation of the immediate early genes Nr4a1, Erg, and Rrad in the SCN of both genotypes. Light stimulation during the subjective night resulted in a strong up-regulation of c...... to light during the subjective night is an immediate expression of several early response genes in the SCN. We show, by quantitative real-time polymerase chain reaction, that the amount of melanopsin mRNA in the retinal ganglion cells is preserved in the blind Crx (-/-) mouse with degenerated classic......-fos in both genotypes with a significantly higher up-regulation in the blind Crx (-/-) mouse. Expression of Grp and Vip, the genes for two classic peptides located in the SCN, was not influenced by light stimulation. The data strongly indicate the involvement of the melanopsin-based non-visual optic system...

  20. Laser-induced stimulated Raman scattering in the forward direction of a droplet - Comparison of Mie theory with geometrical optics

    Science.gov (United States)

    Srivastava, Vandana; Jarzembski, Maurice A.

    1991-01-01

    This paper uses Mie theory to treat electromagnetic scattering and to evaluate field enhancement in the forward direction of a small droplet irradiated by a high-energy beam and compares the results of calculations with the field-enhancement evaluation obtained via geometrical optics treatment. Results of this comparison suggest that the field enhancement located at the critical ring region encircling the axis in the forward direction of the droplet can support laser-induced Raman scattering. The results are supported by experimental observations of the interaction of a 120-micron-diam water droplet with a high-energy Nd:YAG laser beam.

  1. Theoretical assessment of optical resolution enhancement and background fluorescence reduction by three-dimensional nonlinear structured illumination microscopy using stimulated emission depletion

    Science.gov (United States)

    Dake, Fumihiro

    2016-08-01

    Three-dimensional structured illumination microscopy (SIM) enlarges frequency cutoff laterally and axially by a factor of two, compared with conventional microscopy. However, its optical resolution is still fundamentally limited. It is necessary to introduce nonlinearity to enlarge frequency cutoff further. We propose three-dimensional nonlinear structured illumination microscopy based on stimulated emission depletion (STED) effect, which has a structured excitation pattern and a structured STED pattern, and both three-dimensional illumination patterns have the same lateral pitch and orientation. Theoretical analysis showed that nonlinearity induced by STED effect, which causes harmonics and contributes to enlarging frequency cutoff, depends on the phase difference between two structured illuminations and that the phase difference of π is the most efficient to increase nonlinearity. We also found that undesirable background fluorescence, which degenerates the contrast of structured pattern and limits the ability of SIM, can be reduced by our method. These results revealed that optical resolution improvement and background fluorescence reduction would be compatible. The feasibility study showed that our method will be realized with commercially available laser, having 3.5 times larger frequency cutoff compared with conventional microscopy.

  2. Thermoluminescence and optically stimulated luminescence properties of Dy3+-doped CaO-Al2O3-B2O3-based glasses

    Science.gov (United States)

    Yahaba, T.; Fujimoto, Y.; Yanagida, T.; Koshimizu, M.; Tanaka, H.; Saeki, K.; Asai, K.

    2017-02-01

    We developed Dy3+-doped CaO-Al2O3-B2O3 based glasses with Dy concentrations of 0.5, 1.0, and 2.0 mol% using a melt-quenching technique. The as-synthesized glasses were applicable as materials exhibiting thermoluminescence (TL) and optically stimulated luminescence (OSL). The optical and radiation response properties of the glasses were characterized. In the photoluminescence (PL) spectra, two emission bands due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ were observed at 480 and 580 nm. In the OSL spectra, the emission band due to the 4F9/2 → 6H15/2 transition of Dy3+ was observed. Excellent TL and OSL responses were observed for dose ranges of 0.1-90 Gy. In addition, TL fading behavior was better than that of OSL in term of the long-time storage. These results indicate that the Dy3+-doped CaO-Al2O3-B2O3-based glasses are applicable as TL materials.

  3. Stimulated Brillouin scattering in highly birefringent multimode tapered chalcogenide photonic crystal fiber for distributed optical sensors (Retraction Notice)

    Science.gov (United States)

    Baili, Amira; Cherif, Rim; Zghal, Mourad

    2016-09-01

    This paper, originally published on September 15, 2016, was retracted from the SPIE Digital Library on October 5, 2016, due to a high degree of similarity between specific portions of the text of the paper to the following publications: J. Tchahame, J. Beugnot, A. Kudlinski, and T. Sylvestre, "Multimode Brillouin spectrum in a long tapered birefringent photonic crystal fiber," Opt. Lett. 40, 4281-4284 (2015). doi: 10.1364/OL.40.004281 W. W. Ke, X. J. Wang and X. Tang, "Stimulated Brillouin Scattering Model in Multi-Mode Fiber Lasers," in IEEE Journal of Selected Topics in Quantum Electronics, vol. 20, no. 5, pp. 305-314, Sept.-Oct. 2014. doi: 10.1109/JSTQE.2014.2303256.

  4. Comparison of intensity-modulated radiotherapy and volumetric-modulated arc therapy dose measurement for head and neck cancer using optical stimulated luminescence dosimeter

    Science.gov (United States)

    Lai, Lu-Han; Chuang, Keh-Shih; Lin, Hsin-Hon; Liu, Yi-Chi; Kuo, Chiung-Wen; Lin, Jao-Perng

    2017-11-01

    The in-vivo dose distributions of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), a newly developed technique, for head and neck cancer have been investigated for several years. The present study used a head-and-neck RANDO phantom to simulate the clinical conditions of nasopharyngeal carcinoma and compare the radiation doses between VMAT and IMRT. Three types of planning target volume (PTV) profiles were targeted by reducing the PTV surface margin by 0, 3, and 5 mm. An optically stimulated luminescence dosimeter was used to measure the surface doses. The results revealed that VMAT provided on average 16.8-13.8% lower surface doses within the PTV target areas than IMRT. When the PTV margin was reduced by 0 mm, the surface doses for IMRT reached their maximum value, accounting for 75.1% of its prescribed dose (Dp); however, the Dp value of VMAT was only 61.1%. When the PTV margin was reduced by 3 or 5 mm, the surface doses decreased considerably. The observed surface doses were insufficient when the tumours invaded the body surface; however, VMAT exerted larger skin-sparing effects than IMRT when the tumours away from the skin. These results suggest that the skin doses for these two techniques are insufficient for surface tumours. Notably, VMAT can provide lower skin doses for deep tumours.

  5. Wafer-scale crack-free AlGaN on GaN through two-step selective-area growth for optically pumped stimulated emission

    Science.gov (United States)

    Ko, Young-Ho; Bae, Sung-Bum; Kim, Sung-Bock; Kim, Dong Churl; Leem, Young Ahn; Cho, Yong-Hoon; Nam, Eun-Soo

    2016-07-01

    Crack-free AlGaN template has been successfully grown over entire 2-in. wafer by using 2-step selective-area growth (SAG). The GaN truncated structure was obtained by vertical growth mode with low growth temperature. AlGaN of second step was grown under lateral growth mode. Low pressure enhanced the relative ratio of lateral to vertical growth rate as well as absolute overall growth rate. High V/III ratio was favorable for lateral growth mode. Crack-free planar AlGaN was obtained under low pressure of 30 Torr and high V/III ratio of 4400. The AlGaN was crack-free over entire 2-in. wafer and had quite uniform Al-mole fraction. The dislocation density of the AlGaN with 20% Al-composition was as low as ~7.6×108 /cm2, measured by cathodoluminescence. GaN/AlGaN multi-quantum well (MQW) with cladding and waveguide layers were grown on the crack-free AlGaN template with low dislocation density. It was confirmed that the MQW on the AlGaN template emitted the stimulated emission at 355.5 nm through optical pumping experiment. The AlGaN obtained by 2-step SAG would provide high crystal quality for highly-efficient optoelectronic devices as well as the ultraviolet laser diode.

  6. New ages for Middle and Later Stone Age deposits at Mumba rockshelter, Tanzania: optically stimulated luminescence dating of quartz and feldspar grains.

    Science.gov (United States)

    Gliganic, Luke A; Jacobs, Zenobia; Roberts, Richard G; Domínguez-Rodrigo, Manuel; Mabulla, Audax Z P

    2012-04-01

    The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and report new ages obtained from optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) measurements on single grains of quartz and multi-grain aliquots of potassium (K) feldspar from the MSA and LSA deposits. Measurements of single grains of quartz allowed the rejection of unrepresentative grains and the application of appropriate statistical models to obtain the most reliable age estimates, while measurements of K-feldspars allowed the chronology to be extended to older deposits. The seven quartz ages and four K-feldspar ages provide improved temporal constraints on the archaeological sequence at Mumba. The deposits associated with the latest Kisele Industry (Bed VI-A) and the earliest Mumba Industry (Bed V) are dated to 63.4 ± 5.7 and 56.9 ± 4.8 ka (thousands of years ago), respectively, thus constraining the time of transition between these two archaeological phases to ~60 ka. An age of 49.1 ± 4.3 ka has been obtained for the latest deposits associated with the Mumba Industry, which show no evidence for post-depositional mixing and contain ostrich eggshell (OES) beads and abundant microlithics. The Nasera Industry deposits (Bed III) contain large quantities of OES beads and date to 36.8 ± 3.4 ka. We compare the luminescence ages with the previous chronologies for

  7. Intracavitary in vivo dosimetry based on multichannel fiber-coupled optically stimulated luminescence (OSL) of Al2O3:C for Curietherapy

    International Nuclear Information System (INIS)

    Spasic, Estelle

    2012-01-01

    The brachytherapy is an old technique using sealed radioactive sources of low or average energy. This technique is still therapeutically and economically relevant today and always evolving (e.g. High Dose Rate (HDR) brachytherapy). This treatment enables to deliver a high dose of irradiation in a limited tumoral volume and enables to minimize the risk of radiation-induced cancer as preserving the Organs at Risks (OAR). However, this technique generates high dose gradients, which makes in vivo dosimetry difficult to implement. Hence, the deviations observed between doses delivered and prescribed are often up to the maximal deviation tolerated by the nuclear safety regulations (± 5%) in conformational radiotherapy. Those regulations have been made mandatory in France since 2011. This thesis has been done within the framework of the ANR-TECSAN INTRADOSE project and is based on the past technological benefits demonstrated during the MAESTRO European project and the ANR-TECSAN CODOFER project, in particular a RL/OSL multichannel instrumentation (Radioluminescence - Optically Stimulated Luminescence) made and validated in preclinical evaluation during the MAESTRO project. The purpose of the INTRADOSE project is to demonstrate the feasibility of the intracavitary In Vivo Dosimetry (IVD) by dosimetric catheter using optical fibers and alumina crystals Al 2 O 3 :C with the aim of improving the safety of patients treated by HDR brachytherapy. This new probe enables to measure a dose distribution (several points) close to the OAR, it offers a little diameter (≤ 3 mm) designed for an intracavitary use (e.g. to insert in the urethra), it is transparent, radiation stable and reusable after dose reading and sterilization. During this study, we have first developed this new dosimetric sensor based on the OSL using the properties of the alumina crystal. Several tests have been done in order to evaluate the feasibility and the compatibility with a medical application. Then

  8. SU-F-T-320: Assessing Placement Error of Optically Stimulated Luminescent in Vivo Dosimeters Using Cone-Beam Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Riegel, A; Klein, E [Northwell Health, Lake Success, NY (United States); Tariq, M; Gomez, C [Hofstra University, Hempstead, NY (United States)

    2016-06-15

    Purpose: Optically-stimulated luminescent dosimeters (OSLDs) are increasingly utilized for in vivo dosimetry of complex radiation delivery techniques such as intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Evaluation of clinical uncertainties such as placement error has not been performed. This work retrospectively investigates the magnitude of placement error using conebeam computed tomography (CBCT) and its effect on measured/planned dose agreement. Methods: Each OSLD was placed at a physicist-designated location on the patient surface on a weekly basis. The location was given in terms of a gantry angle and two-dimensional offset from central axis. The OSLDs were placed before daily image guidance. We identified 77 CBCTs from 25 head-and-neck patients who received IMRT or VMAT, where OSLDs were visible on the CT image. Grossly misplaced OSLDs were excluded (e.g. wrong laterality). CBCTs were registered with the treatment plan and the distance between the planned and actual OSLD location was calculated in two dimensions in the beam’s eye view. Distances were correlated with measured/planned dose percent differences. Results: OSLDs were grossly misplaced for 5 CBCTs (6.4%). For the remaining 72 CBCTs, average placement error was 7.0±6.0 mm. These errors were not correlated with measured/planned dose percent differences (R{sup 2}=0.0153). Generalizing the dosimetric effect of placement errors may be unreliable. Conclusion: Correct placement of OSLDs for IMRT and VMAT treatments is critical to accurate and precise in vivo dosimetry. Small placement errors could produce large disagreement between measured and planned dose. Further work includes expansion to other treatment sites, examination of planned dose at the actual point of OSLD placement, and the influence of imageguided shifts on measured/planned dose agreement.

  9. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    Science.gov (United States)

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

  10. Lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, investigated using optically stimulated luminescence dating of beach ridges

    International Nuclear Information System (INIS)

    Li Dewen; Li Yingkui; Ma Baoqi; Zhao, Junxiang; Dong Guocheng; Wang Liqiang

    2009-01-01

    This paper presents a preliminary study on lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, by dating four groups of beach ridges using optically stimulated luminescence (OSL). The highest/oldest beach ridge group (>100 m higher than the current lake level) is dated back to 67.9 ± 2.4 ka BP, corresponding to the early stage of the Last Glaciation (marine isotope stage (MIS) 4). This date further supports that no plateau-scale ice sheet covered the Tibetan Plateau during the Last Glaciation. The other three groups produce OSL ages of 30.4 ± 2.9 to 18.6 ± 1.7, 12.5 ± 1.6 to 9.2 ± 0.5, and 6.9 ± 0.2 ka BP respectively, most likely corresponding to cold or wet climate periods of the late stage of the Last Glaciation (MIS 2), deglaciation, and Holocene Hypsithermal. On the plateau scale, these four beach ridge groups are almost synchronous with advances or standstills of Himalayan glaciers, indicating similar climate controls across the central and southern Tibetan Plateau, and being consistent with the conclusion, obtained from nearby ice core records, that this area is affected by the South Asia monsoon. Furthermore, beach ridges are also synchronous with fluvial terraces in the northern Tibetan Plateau, implying common driving forces during their formation. Therefore, some terraces may be formed as a result of climate events rather than being of tectonic origin.

  11. Efficient bioconversion of organic wastes to high optical activity of l-lactic acid stimulated by cathode in mixed microbial consortium.

    Science.gov (United States)

    Xue, Gang; Lai, Sizhou; Li, Xiang; Zhang, Wenjuan; You, Jiguang; Chen, Hong; Qian, Yajie; Gao, Pin; Liu, Zhenhong; Liu, Yanan

    2017-12-12

    Lactic acid is one of the emerging top biomass derived platform chemicals that can be fermented from organic wastes. This study evaluated the potential of Cathodic Electro-Fermentation (CEF) as a novel approach to enhance the yield of high optical activity (OA) of l-lactic acid from organic wastes using mixed microbial consortium. The fermentation process was stimulated through the cathode applied with -100 mV versus standard hydrogen electrode (SHE), which contributed to 4.73 times higher lactic acid productivity (0.6578 g L -1 h -1 ) compared to that in the open circuit control (0.1392 g L -1 h -1 ), and an improved OA of l-lactic acid was also observed (42.3% vs. 3.6% of the open circuit control). The study elucidated that the optimal voltage at -100 mV promoted the conversion of pyruvate to l-lactate by 77.9% compared to the Blank, which triggered the generation of l-lactic acid to occur rapidly even at low concentration of pyruvate. The significant variation of microbial community in family- and genus-level distributions were observed in CEF system. Furthermore, the open-circuit operation test demonstrated that the cathode providing in-situ electron supply was essential to achieve high efficient bioconversion of organic wastes to lactic acid. Our work highlights the feasibility of CEF to steer high value-added fermentation products deriving from organic wastes by the mixed microbial consortium. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Thermoluminescent dosimetry and of optically stimulated luminescence of diamond films grown up by the chemical vapor deposition technique exposed to beta radiation

    International Nuclear Information System (INIS)

    Melendrez A, R.; Barboza F, M.

    2002-01-01

    A study of the dosimetric properties through the thermoluminescence (Tl) and Optically stimulated luminescence (Lobe) in diamond films grown up by the chemical vapor deposition (Dq) techniques was realized.The films under study have thickness of 6, 12, 180 and 500 microns. The dose range was from 0 to 1.5 KGy, observing for the case of the thermoluminescent dosimetry a linear behavior in the range 0-300 Gy and a supra linearity effect in the range from 300-1500 Gy. For the case of the dosimetry by means of LOE a linear behavior in the range (0-300 Gy) without be enough for the saturation was observed, although some samples exhibit a linear behavior until 1500 Gy (6 microns). The irradiation was realized with a source of Strontium 90 of (40 mCi) and the photoestimulation for realizing the measures of LOE was realized using diodes emitting of laser light (470 nm) which generate until 50 MW/cm 2 . The Tl peak which was used to realize the dosimetry such Tl as LOE was that located around 340 C degrees in the brilliance curve which presents another peaks centered around of 110, 190, and 340 C degrees, depending on the film. It was realized a study of the Tl signal drop and it was observed that after 3 hours the signal was stable reaching a decay of 15 %. the analysis of the drop in the Tl signal, immediately after to irradiate and after to photoestimulate with the blue light laser for observing the LOE, indicated that exists a fall in all the Tl peaks, decaying in greater proportion those of more low temperature. (Author)

  13. The influence of radiation-induced defects on thermoluminescence and optically stimulated luminescence of α-Al{sub 2}O{sub 3}:C

    Energy Technology Data Exchange (ETDEWEB)

    Nyirenda, A.N., E-mail: anyirenda@gmail.com; Chithambo, M.L.

    2017-04-15

    It is known that when α-Al{sub 2}O{sub 3}:C is exposed to excessive amounts of ionising radiation, defects are induced within its matrix. We report the influence of radiation-induced defects on the thermoluminescence (TL) and optically stimulated luminescence (OSL) measured from α-Al{sub 2}O{sub 3}:C after irradiation to 1000 Gy. These radiation-induced defects are thermally unstable in the region 450–650 °C and result in TL peaks in this range when the TL is measured at 1 °C/s. Heating a sample to 700 °C obliterates the radiation-induced defects, that is, the TL peaks corresponding to the radiation induced defects are no longer observed in the subsequent TL measurements when moderate irradiation doses below 10 Gy are used. The charge traps associated with these radiation-induced defects are more stable than the dosimetric trap when the sample is exposed to either sunlight or 470-nm blue light from LEDs. TL glow curves measured following the defect-inducing irradiation produce a dosimetric peak that is broader and positioned at a higher temperature than observed in glow curves obtained before the heavy irradiation. In addition, sample sensitization/desensitization occurs due to the presence of these radiation-induced defects. Furthermore, both the activation energy and the kinetic order of the dosimetric peak evaluated when the radiation-induced defects are present in the sample are significantly lower in value than those obtained when these defects are absent. The radiation-induced defects also affect the shape and total light sum of the OSL signal as well as the position and width of the resultant residual phototransferred thermoluminescence main peak.

  14. Determination of average LET of therapeutic proton beams using Al{sub 2}O{sub 3}:C optically stimulated luminescence (OSL) detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sawakuchi, Gabriel O [Department of Physics, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6 (Canada); Sahoo, Narayan; Titt, Uwe [Department of Radiation Physics, University of Texas M D Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030 (United States); Gasparian, Patricia B R; Rodriguez, Matthew G; Yukihara, Eduardo G [Physics Department, Oklahoma State University, 145 Physical Sciences II, Stillwater, OK 74078 (United States); Archambault, Louis, E-mail: gsawakuc@physics.carleton.c [Centre Hospitalier Universitaire de Quebec (CHUQ), Hotel Dieu de Quebec, Department of Radiation Oncology, 11 Cote du Palais, Quebec City, Quebec G1R 2J6 (Canada); Department of Physics, Laval University, 1045 avenue de la Medecine, Quebec City, Quebec G1V 0A6 (Canada)

    2010-09-07

    In this work we present a methodology and proof of concept to experimentally determine average linear energy transfer (LET) of therapeutic proton beams using the optically stimulated luminescence (OSL) of small Al{sub 2}O{sub 3}:C detectors. Our methodology is based on the fact that the shape of the OSL decay curve of Al{sub 2}O{sub 3}:C detectors depends on the LET of the radiation field. Thus, one can use the shape of the OSL decay curves to establish an LET calibration curve, which in turn permits measurements of LET. We performed irradiations at the M D Anderson Cancer Center Proton Therapy Center, Houston (PTCH), with passive scattering beams. We determined the average LET of the passive scattering beams using a validated Monte Carlo model of the PTCH passive scattering nozzle and correlated them with the shape of the OSL decay curve to obtain an LET calibration curve. Using this calibration curve and OSL measurements, we determined the averaged LET at various water-equivalent depths for therapeutic spread-out Bragg peaks and compared the results with averaged LETs determined using the Monte Carlo simulations. Agreement between measured and simulated fluence-averaged LET was within 24% for low energy spread-out Bragg peak (SOBP) fields and within 14% for high energy SOBP fields. Agreement between measured and simulated dose-averaged LET was within 12% for low energy SOBP fields and within 47% for high energy SOBP fields. The data presented in this work demonstrated the correlation between the OSL decay curve shapes and the average LET of the radiation fields, providing proof of concept of the feasibility of using OSL from Al{sub 2}O{sub 3}:C detectors to measure average LET of therapeutic proton beams.

  15. The late-glacial fluvial terrace t7 at Raunheim (lower River Main), Germany. Constraining the chronological placement by optical stimulated luminescence dating.

    Science.gov (United States)

    Thiemeyer, Heinrich; Kadereit, Annette; Zipf, Lars; Flettner, Stephan

    2017-04-01

    The lower River Main valley exhibits up to seven fluvial terrace levels (t1 - t7, according to the stratigraphy of Semmel 1969). The lowermost terrace (t7) represents the most recently formed level which due to stratigraphical considerations is assumed to be of Late Pleistocene age (Semmel 1969). However, the chronological placement of the terrace has not been determined by numerical dating so far. The area was apparently roamed by Late Palaeolithic people as evidenced by artefacts which were discovered on a former sandy river bank between 87 m and 91 m above sea level on top of the t7 east of the town of Raunheim. We took this opportunity to open four trenches in order to localize additional in situ Palaeolithic artefacts and to investigate the stratigraphy of the sediments and soils and, for the first time, to provide numerical ages in order to narrow down the period of the t7 activity. Eight samples from three profiles in three of the trenches were collected for optical stimulated (OSL) dating. OSL dating occurred applying a blue light stimulated luminescence (BLSL) single aliquot regeneration (SAR) protocol (Murray & Wintle 2000) to small aliquots (few 102 grains) of quartz coarse grain separates (125 - 212 µm). The trenches showed that the t7 sediments consist of fluvial sand over gravel. They are overlain by calcareous loamy and sandy overbank deposits. At the investigated site the Holocene Cambisol at the surface passes into a Gleysol that has developed in a palaeochannel which is incised into the t7. The trenches revealed further that only parts of the Late Palaeolithic site are in situ and therefore contemporaneous with the fluvial sediments beneath the Cambisol. The upper part of the sections consists of colluvial deposits lying on truncated Cambisols. The OSL dating places the section into the period spanning the last glacial maximum (LGM) / late glacial to the late Holocene. The oldest investigated fluvial t7 sediments date around 24.7 ka. Slightly

  16. Estimating dose to implantable cardioverter-defibrillator outside the treatment fields using a skin QED diode, optically stimulated luminescent dosimeters, and LiF thermoluminescent dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Maria F., E-mail: chanm@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Song, Yulin; Dauer, Lawrence T.; Li Jingdong; Huang, David; Burman, Chandra [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    2012-10-01

    The purpose of this work was to determine the relative sensitivity of skin QED diodes, optically stimulated luminescent dosimeters (OSLDs) (microStar Trade-Mark-Sign DOT, Landauer), and LiF thermoluminescent dosimeters (TLDs) as a function of distance from a photon beam field edge when applied to measure dose at out-of-field points. These detectors have been used to estimate radiation dose to patients' implantable cardioverter-defibrillators (ICDs) located outside the treatment field. The ICDs have a thin outer case made of 0.4- to 0.6-mm-thick titanium ({approx}2.4-mm tissue equivalent). A 5-mm bolus, being the equivalent depth of the devices under the patient's skin, was placed over the ICDs. Response per unit absorbed dose-to-water was measured for each of the dosimeters with and without bolus on the beam central axis (CAX) and at a distance up to 20 cm from the CAX. Doses were measured with an ionization chamber at various depths for 6- and 15-MV x-rays on a Varian Clinac-iX linear accelerator. Relative sensitivity of the detectors was determined as the ratio of the sensitivity at each off-axis distance to that at the CAX. The detector sensitivity as a function of the distance from the field edge changed by {+-} 3% (1-11%) for LiF TLD-700, decreased by 10% (5-21%) for OSLD, and increased by 16% (11-19%) for the skin QED diode (Sun Nuclear Corp.) at the equivalent depth of 5 mm for 6- or 15-MV photon energies. Our results showed that the use of bolus with proper thickness (i.e., {approx}d{sub max} of the photon energy) on the top of the ICD would reduce the scattered dose to a lower level. Dosimeters should be calibrated out-of-field and preferably with bolus equal in thickness to the depth of interest. This can be readily performed in clinic.

  17. Development and implementation of a remote audit tool for high dose rate (HDR) Ir-192 brachytherapy using optically stimulated luminescence dosimetry

    International Nuclear Information System (INIS)

    Casey, Kevin E.; Kry, Stephen F.; Howell, Rebecca M.; Followill, David; Alvarez, Paola; Lawyer, Ann

    2013-01-01

    Purpose: The aim of this work was to create a mailable phantom with measurement accuracy suitable for Radiological Physics Center (RPC) audits of high dose-rate (HDR) brachytherapy sources at institutions participating in National Cancer Institute-funded cooperative clinical trials. Optically stimulated luminescence dosimeters (OSLDs) were chosen as the dosimeter to be used with the phantom.Methods: The authors designed and built an 8 × 8 × 10 cm 3 prototype phantom that had two slots capable of holding Al 2 O 3 :C OSLDs (nanoDots; Landauer, Glenwood, IL) and a single channel capable of accepting all 192 Ir HDR brachytherapy sources in current clinical use in the United States. The authors irradiated the phantom with Nucletron and Varian 192 Ir HDR sources in order to determine correction factors for linearity with dose and the combined effects of irradiation energy and phantom characteristics. The phantom was then sent to eight institutions which volunteered to perform trial remote audits.Results: The linearity correction factor was k L = (−9.43 × 10 −5 × dose) + 1.009, where dose is in cGy, which differed from that determined by the RPC for the same batch of dosimeters using 60 Co irradiation. Separate block correction factors were determined for current versions of both Nucletron and Varian 192 Ir HDR sources and these vendor-specific correction factors differed by almost 2.6%. For the Nucletron source, the correction factor was 1.026 [95% confidence interval (CI) = 1.023–1.028], and for the Varian source, it was 1.000 (95% CI = 0.995–1.005). Variations in lateral source positioning up to 0.8 mm and distal/proximal source positioning up to 10 mm had minimal effect on dose measurement accuracy. The overall dose measurement uncertainty of the system was estimated to be 2.4% and 2.5% for the Nucletron and Varian sources, respectively (95% CI). This uncertainty was sufficient to establish a ±5% acceptance criterion for source strength audits under a

  18. Fiber remote and real time optoelectronic dosimetry based on the optically stimulated luminescence phenomenon: Development of sensors based on aluminium oxide doped with carbon for applications in personal dosimetry

    International Nuclear Information System (INIS)

    Ranchoux, G.

    2001-01-01

    An optical fiber sensor based on the use of classical technologies (optoelectronic, laser, optical fibers,...) can be connected to the Optically Stimulated Luminescence properties (or OSL) of the aluminium oxide doped with carbon in order to provide several new capabilities compared to usual dosimeters: remote dose measurements, quasi 'real time' dose measurements, applied to personal dosimetry thanks to a low fading level at room temperature. This thesis work shows the studies about: 1)the state of the art about dosimetry based on the aluminium oxide doped with carbon and its OSL properties (emission and stimulation spectra, glow curves, trap and recombination energy levels,...), 2)the state of the art about international standardization, not only, with regard to personal dosimetry (IEC 61066 Standard) but also to the description of operational quantities called personal dose equivalent H p (10) and H p (0,07), 3)the experimental development of a new sensor device based on aluminium oxide crystals (design, realization, tests,...), 4)the application of statistical Monte Carlo calculation methods (code MCNP4B) to the simulation of the sensor head in accordance with the IEC Standard 61066 with regard to the energy and angular response H p (10). (author) [fr

  19. Optically stimulated luminescence and thermoluminescence in CVD diamond and dosimetric evaluation in fields of ionizing radiation; Luminiscencia opticamente estimulada y termoluminiscencia en diamante DQV y evaluacion dosimetrica en campos de radiacion ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Barboza F, M.; Chernov, V.; Pedroza M, M. [Centro de Investigaciones en Fisica, Universidad de Sonora, A.P. 5-088, 83190 Hermosillo, Sonora (Mexico); Schreck, M. [Universitat Augsburg, Institut fur Physik D-86135, Augsburg (Germany); Preciado F, S.; Melendrez, R. [Universidad de Sonora, A.P. 130, 83000 Hermosillo, Sonora (Mexico)

    2006-07-01

    The optically stimulated luminescence (OSL) results a highly appropriate dosimetric technique for readings of absorbed radiation 'in alive' and 'in situ', as well as in real time. The CVD diamond on the other hand presents excellent qualities like radiation reader thanks to its reproducibility, radiation resistance, biocompatibility and non toxicity. The present work studies the answer of two diamond films pure and polluted with nitrogen (750 ppm) grown by the Chemical Vapor Deposition method (CVD) on silicon substrate (001) irradiated with beta (Sr-90) in the 0.833-100 Gy interval. The optical stimulation was carried out by 40 seconds with infrared laser (830 nm, 0.36 W/cm{sup 2}) and the filter BG-39 (300-600 nm) coupled the PM. The intensity and the decay of the hyperbolic type of the LOE curves were similar in both samples, for the non doped diamond were observed trapping states in 200-380 C being compared with those that it presents the polluted diamond with nitrogen in 80-277 C. The dosimetric behavior in the pure sample is observed lineal in two regions 0-16 Gy and in 30-100 Gy, only the doped sample didn't present linearity in the all range of the studied dose. The advantage is stood out of LOE on TL because the first one not requires of thermal stimulation in such a way that is more appropriate to detect and to measure radiation doses in biomedicine. (Author)

  20. An implantable wireless optogenetic stimulation system for peripheral nerve control.

    Science.gov (United States)

    Kang-Il Song; Park, Sunghee E; Myoung-Soo Kim; Chulmin Joo; Yong-Jun Kim; Suh, Jun-Kyo F; Dosik Hwang; Inchan Youn

    2015-08-01

    An implantable wireless optogenetic stimulation system with an LED-based optical stimulation cuff electrode was developed for peripheral nerve control. The proposed system consisted of a battery-powered optical cuff electrode, optical stimulation controller, and wireless communication system. The optical cuff electrode had a polydimethylsiloxane (PDMS) structure was designed to illuminate the entire sciatic nerve. The wireless communication system was designed to comply with medical implant communication service (MICS) regulations. To evaluate the proposed system, optogenetic stimulation was performed in optogenetic transgenic mice (Thy1::ChR2). The optical cuff electrode was implanted on the sciatic nerve, and movement was elicited during optical stimulation. The experimental results show that ankle movement can be generated wirelessly using optical stimulation pulse parameters.

  1. Using optical tweezers to examine the chemotactic force to a single inflammatory cell--eosinophil stimulated by chemoattractants prepared from Toxocara Canis larvae

    Science.gov (United States)

    Shih, Po-Chen; Su, Yi-Jr; Chen, Ke-Min; Jen, Lin-Ni; Liu, Cheng-tzu; Hsu, Long

    2005-08-01

    Granulocytes are a group of white blood cells belonging to the innate immune system in human and in murine in which eosinophils play an important role in worm infection-induced inflammation. The migration of these cells is well characterized and has been separated into four steps: rolling, adhesion, transendothelial migration, and chemotaxis, however, the physical characteristics of the chemotactic force to eosinophils from worm component remain largely unknown. Note that optical tweezers are featured in the manipulation of a single cell and the measurement of biological forces. Therefore, we propose to use optical tweezers to examine the chemotactic force to a eosinophil from a T. canis lavae preparation in terms of distance during the migration of eosinophil.

  2. 50 years of nonlinear optics

    International Nuclear Information System (INIS)

    Shen Yuanrang

    2011-01-01

    This article presents a brief introduction to the birth and early investigations of nonlinear optics, such as second harmonic generation,sum and difference frequency generation, stimulated Raman scattering,and self-action of light etc. Several important research achievements and applications of nonlinear optics are presented as well, including nonlinear optical spectroscopy, phase conjugation and adaptive optics, coherent nonlinear optics, and high-order harmonic generation. In the end, current and future research topics in nonlinear optics are summarized. (authors)

  3. The red, white and blue of quartz luminescence: A comparison of D{sub e} values derived for sediments from Australia and Indonesia using thermoluminescence and optically stimulated luminescence emissions

    Energy Technology Data Exchange (ETDEWEB)

    Westaway, K.E. [Department of Environment and Geography, Faculty of Science, Macquarie University, NSW 2109 (Australia)], E-mail: kira@els.mq.edu.au

    2009-05-15

    Heated quartz, including quartz from volcanic provinces, commonly displays different luminescence characteristics compared with the same mineral in non-volcanic contexts. These differing properties demand thorough investigations into the most suitable dating techniques for samples composed of quartz grains with different origins. In cave settings, independent techniques such as radiocarbon and U-series can prove useful for validating results, but further insights may be gained by comparing the results obtained for quartz using different luminescence emissions. Twenty-two quartz samples have been selected from five areas (Australia, Timor, Flores, Java and Sulawesi) for comparison of the red and blue emissions. The dual-aliquot regenerative-dose protocol was used to estimate the equivalent dose (D{sub e}) associated with the light-sensitive red thermoluminescence while the single aliquot regenerative-dose protocol was used to measure the D{sub e} values for single grains and single aliquots, which were optically stimulated by green or blue light, respectively. The results obtained from the red thermoluminescence and optically stimulated luminescence measurements display good agreement with independent dating techniques (within {approx}20%). However, the blue emissions exhibit a thermally unstable component, which causes a large underestimation in palaeodoses (on average {approx}80%) and an age limit of {approx}25 ka, while the red emissions are more thermally stable over geological timescales but produce an overestimation in red TL ages (by {approx}13 ka) and low precision (typically {approx}24%). These results can be correlated to three different quartz groups, which have been divided according to their luminescence emissions.

  4. Thermoluminescence and optically stimulated luminescence properties of Dy{sup 3+}-doped CaO–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3}-based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yahaba, T., E-mail: takuma.yahaba.s1@dc.tohoku.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Fujimoto, Y. [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Yanagida, T. [Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma 630-0192 (Japan); Koshimizu, M.; Tanaka, H.; Saeki, K.; Asai, K. [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan)

    2017-02-01

    We developed Dy{sup 3+}-doped CaO–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} based glasses with Dy concentrations of 0.5, 1.0, and 2.0 mol% using a melt-quenching technique. The as-synthesized glasses were applicable as materials exhibiting thermoluminescence (TL) and optically stimulated luminescence (OSL). The optical and radiation response properties of the glasses were characterized. In the photoluminescence (PL) spectra, two emission bands due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2} and {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2} transitions of Dy{sup 3+} were observed at 480 and 580 nm. In the OSL spectra, the emission band due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2} transition of Dy{sup 3+} was observed. Excellent TL and OSL responses were observed for dose ranges of 0.1–90 Gy. In addition, TL fading behavior was better than that of OSL in term of the long-time storage. These results indicate that the Dy{sup 3+}-doped CaO–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3}-based glasses are applicable as TL materials.

  5. Luminescence excitation characteristics of Ca-, Na- and K-aluminosilicates (feldspars), in the stimulation range 20-500 eV: optical detection of XAS

    CERN Document Server

    Poolton, N R J; Quinn, F M; Pantos, E; Andersen, C E; Bøtter-Jensen, L; Johnsen, O; Murray, A S

    2003-01-01

    We demonstrate that the visible/UV luminescence from common feldspar crystals (NaAlSi sub 3 O sub 8 , KAlSi sub 3 O sub 8 and CaAl sub 2 Si sub 2 O sub 8) can be used to detect detailed L-edge and associated near-edge absorption structure of the main constituent atoms (Ca, K, Na, Al, Si), when exciting in the energy range 20-500 eV. Comparisons of the spectral features are drawn with similar measurements made on the associated materials SiO sub 2 , Al sub 2 O sub 3 and CaCO sub 3. The potential for using optically detected x-ray absorption spectroscopy as a method for identifying the luminescent components of mixed mineral samples is considered.

  6. Optics/Optical Diagnostics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Optics/Optical Diagnostics Laboratory supports graduate instruction in optics, optical and laser diagnostics and electro-optics. The optics laboratory provides...

  7. Brain Stimulation Therapies

    Science.gov (United States)

    ... Magnetic Seizure Therapy Deep Brain Stimulation Additional Resources Brain Stimulation Therapies Overview Brain stimulation therapies can play ... for a shorter recovery time than ECT Deep Brain Stimulation Deep brain stimulation (DBS) was first developed ...

  8. Kinetics of infrared stimulated luminescence from feldspars

    DEFF Research Database (Denmark)

    Jain, Mayank; Sohbati, Reza; Guralnik, Benny

    2015-01-01

    thermal and optical, of the infrared stimulated luminescence signal from feldspar. Based on the application of this model, it is concluded that different infra-red stimulated luminescence emissions (UV, blue, yellow and far-red) follow the same kinetics, and, therefore, involve participation of the same...... in feldspar. © 2015 Elsevier Ltd. All rights reserved....

  9. Violet stimulated luminescence: geo- or thermochronometer?

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Guralnik, Benny; Porat, N.

    2015-01-01

    The method of quartz optically stimulated luminescence (OSL) dating is widely used, but generally limited to the past ~0.1 million years (Ma) due to early saturation of the desired signal. Violet stimulated luminescence (VSL) of quartz has previously been shown as a promising alternative...

  10. Atomic oxygen stimulated outgassing

    Science.gov (United States)

    Linton, Roger C.; Reynolds, John M.

    1991-01-01

    The passive Long Duration Exposure Facility (LDEF) Experiment A0034, Atomic Oxygen Simulated Outgassing, consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge and, for reference, to the relative wake environment on the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of the various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and a optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to the RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

  11. Thyroid dose measurement in patients undergoing to digital orthopantomography using optical stimulation dosimeters; Medicion de dosis en tiroides en pacientes sometidos a ortopantografia digital utilizando dosimetros de estimulacion optica

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez M, J. G.; Lopez V, A.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Calz. Legaria 694, Col. Irrigacion, 11500 Ciudad de Mexico (Mexico); Avalos P, L. Y., E-mail: jggm25@yahoo.com.mx [UNAM, Facultad de Odontologia, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico)

    2016-10-15

    In this paper we present the study of the thyroid equivalent dose in 300 patients undergoing to digital orthopantomography for dental treatment purposes using optical stimulation dosimeters (OSL) as in-vivo dosimeters, in order to verify if this is within acceptable parameters to prevent stochastic risks and to evaluate the possible risks caused by the technique used for this type of study (66 kv, 5 m A, 14.1 s). Three OSL dosimeters were used per patient, which were placed by the physician on the skin above the thyroid gland (using anatomical references and palpation); the information of the patients was divided by neck size and sex, finding a slight increase in the equivalent dose for female and small size patient, this combination being the group that was submitted to a higher dose. The results obtained were compared with similar studies performed on anthropomorphic mannequins with TLD dosimeters obtaining lower results. The equivalent dose found even though is below the threshold stochastic damage must be motorized for radiological protection and registration purposes. (Author)

  12. Optically stimulated luminescence in retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Murray, A.S.

    2002-01-01

    of this programme, including the evaluation of the single-aliquot regenerative-dose (SAR) measurement protocol with brick quartz and the determination of dose-depth profiles in building materials as a guide to determining the mean energy of the incident radiation. Investigations into heated materials are most...... advanced, and a lower detection limit for quartz extracted from Chernobyl bricks was determined to be aliquot and single-grain techniques have been used...

  13. Electron Gyro-Harmonic Effects on Ionospheric Stimulated Brillouin Scatter

    Science.gov (United States)

    2014-08-21

    SECURITY CLASSIFICATION OF: Stimulated Brillouin scattering (SBS) and resonant phenomena are well known in the context of laser fusion, fiber optics ... fiber optics , and piezoelectric semiconductor plasmas, as well as in various biological applications. Due to recent advances, active space experiments... fiber optics , and piezoelectric semiconductor plasmas, as well as in various biological applications. Due to recent advances, active space

  14. Biomarkers and Stimulation Algorithms for Adaptive Brain Stimulation

    Directory of Open Access Journals (Sweden)

    Kimberly B. Hoang

    2017-10-01

    Full Text Available The goal of this review is to describe in what ways feedback or adaptive stimulation may be delivered and adjusted based on relevant biomarkers. Specific treatment mechanisms underlying therapeutic brain stimulation remain unclear, in spite of the demonstrated efficacy in a number of nervous system diseases. Brain stimulation appears to exert widespread influence over specific neural networks that are relevant to specific disease entities. In awake patients, activation or suppression of these neural networks can be assessed by either symptom alleviation (i.e., tremor, rigidity, seizures or physiological criteria, which may be predictive of expected symptomatic treatment. Secondary verification of network activation through specific biomarkers that are linked to symptomatic disease improvement may be useful for several reasons. For example, these biomarkers could aid optimal intraoperative localization, possibly improve efficacy or efficiency (i.e., reduced power needs, and provide long-term adaptive automatic adjustment of stimulation parameters. Possible biomarkers for use in portable or implanted devices span from ongoing physiological brain activity, evoked local field potentials (LFPs, and intermittent pathological activity, to wearable devices, biochemical, blood flow, optical, or magnetic resonance imaging (MRI changes, temperature changes, or optogenetic signals. First, however, potential biomarkers must be correlated directly with symptom or disease treatment and network activation. Although numerous biomarkers are under consideration for a variety of stimulation indications the feasibility of these approaches has yet to be fully determined. Particularly, there are critical questions whether the use of adaptive systems can improve efficacy over continuous stimulation, facilitate adjustment of stimulation interventions and improve our understanding of the role of abnormal network function in disease mechanisms.

  15. Optic neuritis

    Science.gov (United States)

    Retro-bulbar neuritis; Multiple sclerosis - optic neuritis; Optic nerve - optic neuritis ... The exact cause of optic neuritis is unknown. The optic nerve carries visual information from your eye to the brain. The nerve can swell when ...

  16. Phonon-induced optical superlattice.

    Science.gov (United States)

    de Lima, M M; Hey, R; Santos, P V; Cantarero, A

    2005-04-01

    We demonstrate the formation of a dynamic optical superlattice through the modulation of a semiconductor microcavity by stimulated acoustic phonons. The high coherent phonon population produces a folded optical dispersion relation with well-defined energy gaps and renormalized energy levels, which are accessed using reflection and diffraction experiments.

  17. Stimulated coherent transition radiation

    International Nuclear Information System (INIS)

    Hung-chi Lihn.

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed

  18. Thermally stimulated luminescence studies in combustion ...

    Indian Academy of Sciences (India)

    Wintec

    resonance, photoacoustic studies/optical absorption etc in order to understand the TSL mechanism leading to gene- ration and trapping of defect centres due to ionizing radiation and light emission in aluminum oxide during thermal stimulation. Figure 3 shows the variation of TSL intensity with γ- ray dose in combustion ...

  19. Considering optogenetic stimulation for cochlear implants.

    Science.gov (United States)

    Jeschke, Marcus; Moser, Tobias

    2015-04-01

    Electrical cochlear implants are by far the most successful neuroprostheses and have been implanted in over 300,000 people worldwide. Cochlear implants enable open speech comprehension in most patients but are limited in providing music appreciation and speech understanding in noisy environments. This is generally considered to be due to low frequency resolution as a consequence of wide current spread from stimulation contacts. Accordingly, the number of independently usable stimulation channels is limited to less than a dozen. As light can be conveniently focused, optical stimulation might provide an alternative approach to cochlear implants with increased number of independent stimulation channels. Here, we focus on summarizing recent work on optogenetic stimulation as one way to develop optical cochlear implants. We conclude that proof of principle has been presented for optogenetic stimulation of the cochlea and central auditory neurons in rodents as well as for the technical realization of flexible μLED-based multichannel cochlear implants. Still, much remains to be done in order to advance the technique for auditory research and even more for eventual clinical translation. This article is part of a Special Issue entitled . Copyright © 2015. Published by Elsevier B.V.

  20. Stimulated Brillouin processes in crystals and glasses

    International Nuclear Information System (INIS)

    Faris, G.W.; Hickman, A.P.

    1992-02-01

    The basic physics and material properties needed to describe and predict the Brillouin gain for a variety of materials have been investigated. Lawrence Livermore National Laboratory (LLNL) has identified transverse stimulated Brillouin scattering (SBS) as an important limiting mechanism in high power laser fusion systems. At sufficiently high laser intensities, SBS drives acoustic vibrations that can damage optical components. SRI has performed measurements and developed the corresponding theory for stimulated Brillouin gain spectroscopy in anisotropic crystals. Absolute Brillouin steady-state gain coefficients, linewidths, and frequency shifts have been determined at 532 nm for a number of optical materials of interest to LLNL. This knowledge can be used to select optical materials and devise suppression schemes that will allow much higher laser fluences to be used in laser fusion

  1. Feldspar, Infrared Stimulated Luminescence

    DEFF Research Database (Denmark)

    Jain, Mayank

    2014-01-01

    This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars.......This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars....

  2. Growth hormone stimulation test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003377.htm Growth hormone stimulation test To use the sharing features on this page, please enable JavaScript. The growth hormone (GH) stimulation test measures the ability of the ...

  3. Spinal cord stimulation

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007560.htm Spinal cord stimulation To use the sharing features on this page, please enable JavaScript. Spinal cord stimulation is a treatment for pain that uses ...

  4. Stimulation-induced cerebral glycolytic glucose metabolism

    International Nuclear Information System (INIS)

    Ackermann, R.F.; Lear, J.L.

    1989-01-01

    The authors have developed a method to estimate the relative amounts of cerebral oxidative and glycolytic glucose metabolism with sequentially administered radiolabeled fluorode-oxyglucose (FDG) and 6-glucose (GLU). Cerebral FDG metabolite concentration was found to reflect total glucose metabolism. Cerebral GLU metabolite concentration, however, was found to reflect mainly oxidative metabolism, because of significant fraction of the radiolabel was lost through lactate production and diffusion from the brain with glycolysis. The authors applied the method to normal rats, to seizing rats, and to optically stimulated rats. Normal cerebral glucose metabolism was primarily oxidative, but stimulation caused profound increases in glycolysis in activated brain regions

  5. Transdermal optogenetic peripheral nerve stimulation

    Science.gov (United States)

    Maimon, Benjamin E.; Zorzos, Anthony N.; Bendell, Rhys; Harding, Alexander; Fahmi, Mina; Srinivasan, Shriya; Calvaresi, Peter; Herr, Hugh M.

    2017-06-01

    Objective: A fundamental limitation in both the scientific utility and clinical translation of peripheral nerve optogenetic technologies is the optical inaccessibility of the target nerve due to the significant scattering and absorption of light in biological tissues. To date, illuminating deep nerve targets has required implantable optical sources, including fiber-optic and LED-based systems, both of which have significant drawbacks. Approach: Here we report an alternative approach involving transdermal illumination. Utilizing an intramuscular injection of ultra-high concentration AAV6-hSyn-ChR2-EYFP in rats. Main results: We demonstrate transdermal stimulation of motor nerves at 4.4 mm and 1.9 mm depth with an incident laser power of 160 mW and 10 mW, respectively. Furthermore, we employ this technique to accurately control ankle position by modulating laser power or position on the skin surface. Significance: These results have the potential to enable future scientific optogenetic studies of pathologies implicated in the peripheral nervous system for awake, freely-moving animals, as well as a basis for future clinical studies.

  6. Quantum optics

    National Research Council Canada - National Science Library

    Agarwal, G. S

    2013-01-01

    .... Focusing on applications of quantum optics, the textbook covers recent developments such as engineering of quantum states, quantum optics on a chip, nano-mechanical mirrors, quantum entanglement...

  7. Optical Computing

    Indian Academy of Sciences (India)

    Optics has been used in computing for a number of years but the main emphasis has been and continues to be to link portions of computers, for communications, or more intrin- sically in devices that have some optical application or component (optical pattern recognition, etc). Optical digi- tal computers are still some years ...

  8. [Transcranial magnetic stimulation].

    Science.gov (United States)

    Tormos, J M; Catalá, M D; Pascual-Leone, A

    Transcranial magnetic stimulation (TMS) permits stimulation of the cerebral cortex in humans without requiring open access to the brain and is one of the newest tools available in neuroscience. There are two main types of application: single-pulse TMS and repetitive TMS. The magnetic stimulator is composed of a series of capacitors that store the voltage necessary to generate a stimulus of the sufficient intensity of generate an electric field in the stimulation coil. The safety of TMS is supported by the considerable experience derived from studies involving electrical stimulation of the cortex in animals and humans, and also specific studies on the safety of TMS in humans. In this article we review historical and technical aspects of TMS, describe its adverse effects and how to avoid them, summarize the applications of TMS in the investigation of different cerebral functions, and discuss the possibility of using TMS for the treatment of neuropsychiatric disorders.

  9. Development of optical sciences in Poland

    Science.gov (United States)

    Romaniuk, Ryszard S.

    2013-10-01

    Research and technical communities for optics, photonics and optoelectronics is grouped in this country in several organizations and institutions. These are: Photonics Society of Poland (PSP), Polish Committee of Optoelectronics of SEP, Photonics Section of KEiT PAN, Laser Club at WAT, and Optics Section of PTF. Each of these communities keeps slightly different specificity. PSP publishes a quarterly journal Photonics Letters of Poland, stimulates international cooperation, and organizes conferences during Industrial Fairs on Innovativeness. PKOpto SEP organizes didactic diploma competitions in optoelectronics. KEiT PAN takes patronage over national conferences in laser technology, optical fiber technology and communications, and photonics applications. SO-PTF has recently taken a decision to organize a cyclic event "Polish Optical Conference". The third edition of this conference PKO'2013 was held in Sandomierz on 30.06-04.07.2013. The conference scientific and technical topics include: quantum and nonlinear optics, photon physics, optic and technology of lasers and other sources of coherent radiation, optoelectronics, optical integrated circuits, optical fibers, medical optics, instrumental optics, optical spectroscopy, optical metrology, new optical materials, applications of optics, teaching in optics. This paper reviews chosen works presented during the III Polish Optical Conference (PKO'2013), representing the research efforts at different national institutions.

  10. Engineering Optics

    CERN Document Server

    Iizuka, Keigo

    2008-01-01

    Engineering Optics is a book for students who want to apply their knowledge of optics to engineering problems, as well as for engineering students who want to acquire the basic principles of optics. It covers such important topics as optical signal processing, holography, tomography, holographic radars, fiber optical communication, electro- and acousto-optic devices, and integrated optics (including optical bistability). As a basis for understanding these topics, the first few chapters give easy-to-follow explanations of diffraction theory, Fourier transforms, and geometrical optics. Practical examples, such as the video disk, the Fresnel zone plate, and many more, appear throughout the text, together with numerous solved exercises. There is an entirely new section in this updated edition on 3-D imaging.

  11. Performance Enhancement by Brain Stimulation

    Directory of Open Access Journals (Sweden)

    Parisa Gazerani

    2017-09-01

    address these uncertainties or providing an optical protocol. Discussing neuro-enhancement with sport bodies, athletes, and authorities seems necessary to facilitate providing a technical, ethical, or regulatory framework for further investigation (Park K, 2017. In contrast to many other substances or strategies listed in prohibited performance-enhancing drugs or strategies, neuro-enhancement cannot be detected with a simple blood test. In addition, since these techniques can be used differently for different types of sport activities, it is not easy to determine whether it must be prohibited or be given legitimacy as an aid to training and development of athletes. In short, although brain stimulation is a valuable scientific tool and a beneficial medical procedure, it does not look wise to let it be used limitlessly and for non-medical purposes at least for the time being that several points are unanswered about efficacy and safety.

  12. Stimulant-induced trichotillomania.

    Science.gov (United States)

    Hamalian, Gareen; Citrome, Leslie

    2010-01-01

    A prior report described the presentation of cocaine-induced trichotillomania, which resolved with the cessation of cocaine use. Here the authors describe the case of stimulant-induced trichotillomania that resolved with the discontinuation of stimulants and initiation of olanzapine. To the authors' knowledge this is the first reported adult case of stimulant-induced trichotillomania. The case is of a patient with a previous diagnosis of attention deficit hyperactivity disorder whose symptoms of trichotillomania coincide with abuse of amphetamine and with the resolution of symptoms in the absence of amphetamine use. Given the increase in exposure of prescription amphetamines among adults, further study into the association between stimulants and adverse events such as trichotillomania is needed.

  13. Vagus Nerve Stimulation

    Science.gov (United States)

    ... you do certain activities such as public speaking, singing or exercising, or when you're eating if ... of life. Research is still mixed on the benefits of vagus nerve stimulation for the treatment of ...

  14. Multipolar intrafascicular stimulation

    NARCIS (Netherlands)

    Meier, Jan H.; Meier, J.H.; Rutten, Wim

    1992-01-01

    The suppressing effect of two intrafascicular anodes on the neural recruitment elicited by one intrafascicular cathode has been studied. Recruitment curves are calculated with a nerve stimulation model and are compared to experimental curves for the peroneal nerve of rat.

  15. Adiabatic passage of light in coupled optical waveguides

    International Nuclear Information System (INIS)

    Longhi, Stefano

    2006-01-01

    Adiabatic passage of light in coupled optical waveguides with a curved axis is theoretically investigated and shown to bear a close connection with coherent population transfer among quantum states of atoms and molecules. In particular, the optical analog of stimulated Raman adiabatic passage can be realized in a three-waveguide optical directional coupler

  16. Applied optics

    International Nuclear Information System (INIS)

    Orszag, A.; Antonetti, A.

    1988-01-01

    The 1988 progress report, of the Applied Optics laboratory, of the (Polytechnic School, France), is presented. The optical fiber activities are focused on the development of an optical gyrometer, containing a resonance cavity. The following domains are included, in the research program: the infrared laser physics, the laser sources, the semiconductor physics, the multiple-photon ionization and the nonlinear optics. Investigations on the biomedical, the biological and biophysical domains are carried out. The published papers and the congress communications are listed [fr

  17. Hamilton's Optics

    Indian Academy of Sciences (India)

    IAS Admin

    Hamiton, optics, wavefronts, characterisic function, conical refraction. . Hamilton's Optics. The Power of Wavefronts. Rajaram Nityananada. Building on work by Fermat and Huygens, Hamil- ton transformed the study of geometrical optics in his very first paper, presented when still in his teens. His 'characteristic function' was ...

  18. Optogenetic stimulation effectively enhances intrinsically generated network synchrony

    Directory of Open Access Journals (Sweden)

    Ahmed eEl Hady

    2013-10-01

    Full Text Available Synchronized bursting is found in many brain areas and has also been implicated in the pathophysiology of neuropsychiatric disorders such as epilepsy, Parkinson’s disease and schizophrenia. Despite extensive studies of network burst synchronization, it is insufficiently understood how this type of network wide synchronization can be strengthened, reduced or even abolished. We combined electrical recording using multi-electrode array with optical stimulation of cultured channelrhodopsin-2 transducted hippocampal neurons to study and manipulate network burst synchronization. We found low frequency photo-stimulation protocols that are sufficient to induce potentiation of network bursting, modifying bursting dynamics and increasing interneuronal synchronization. Surprisingly, slowly fading-in light stimulation, which substantially delayed and reduced light driven spiking, was at least as effective in reorganizing network dynamics as much stronger pulsed light stimulation. Our study shows that mild stimulation protocols that do not enforce particular activity patterns onto the network can be highly effective inducers of network-level plasticity.

  19. Optogenetic stimulation effectively enhances intrinsically generated network synchrony

    Science.gov (United States)

    El Hady, Ahmed; Afshar, Ghazaleh; Bröking, Kai; Schlüter, Oliver M.; Geisel, Theo; Stühmer, Walter; Wolf, Fred

    2013-01-01

    Synchronized bursting is found in many brain areas and has also been implicated in the pathophysiology of neuropsychiatric disorders such as epilepsy, Parkinson’s disease, and schizophrenia. Despite extensive studies of network burst synchronization, it is insufficiently understood how this type of network wide synchronization can be strengthened, reduced, or even abolished. We combined electrical recording using multi-electrode array with optical stimulation of cultured channelrhodopsin-2 transducted hippocampal neurons to study and manipulate network burst synchronization. We found low frequency photo-stimulation protocols that are sufficient to induce potentiation of network bursting, modifying bursting dynamics, and increasing interneuronal synchronization. Surprisingly, slowly fading-in light stimulation, which substantially delayed and reduced light-driven spiking, was at least as effective in reorganizing network dynamics as much stronger pulsed light stimulation. Our study shows that mild stimulation protocols that do not enforce particular activity patterns onto the network can be highly effective inducers of network-level plasticity. PMID:24155695

  20. Optogenetic versus Electrical Stimulation of Human Cardiomyocytes: Modeling Insights

    Science.gov (United States)

    Williams, John C.; Entcheva, Emilia

    2015-01-01

    Optogenetics provides an alternative to electrical stimulation to manipulate membrane voltage, and trigger or modify action potentials (APs) in excitable cells. We compare biophysically and energetically the cellular responses to direct electrical current injection versus optical stimulation mediated by genetically expressed light-sensitive ion channels, e.g., Channelrhodopsin-2 (ChR2). Using a computational model of ChR2(H134R mutant), we show that both stimulation modalities produce similar-in-morphology APs in human cardiomyocytes, and that electrical and optical excitability vary with cell type in a similar fashion. However, whereas the strength-duration curves for electrical excitation in ventricular and atrial cardiomyocytes closely follow the theoretical exponential relationship for an equivalent RC circuit, the respective optical strength-duration curves significantly deviate, exhibiting higher nonlinearity. We trace the origin of this deviation to the waveform of the excitatory current—a nonrectangular self-terminating inward current produced in optical stimulation due to ChR2 kinetics and voltage-dependent rectification. Using a unifying charge measure to compare energy needed for electrical and optical stimulation, we reveal that direct electrical current injection (rectangular pulse) is more efficient at short pulses, whereas voltage-mediated negative feedback leads to self-termination of ChR2 current and renders optical stimulation more efficient for long low-intensity pulses. This applies to cardiomyocytes but not to neuronal cells (with much shorter APs). Furthermore, we demonstrate the cell-specific use of ChR2 current as a unique modulator of intrinsic activity, allowing for optical control of AP duration in atrial and, to a lesser degree, in ventricular myocytes. For self-oscillatory cells, such as Purkinje, constant light at extremely low irradiance can be used for fine control of oscillatory frequency, whereas constant electrical stimulation

  1. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  2. Optical fibres

    CERN Document Server

    Geisler, J; Boutruche, J P

    1986-01-01

    Optical Fibers covers numerous research works on the significant advances in optical fibers, with particular emphasis on their application.This text is composed of three parts encompassing 15 chapters. The first part deals with the manufacture of optical fibers and the materials used in their production. The second part describes optical-fiber connectors, terminals and branches. The third part is concerned with the major optoelectronic components encountered in optical-communication systems.This book will be of value to research scientists, engineers, and patent workers.

  3. Optical interconnects

    CERN Document Server

    Chen, Ray T

    2006-01-01

    This book describes fully embedded board level optical interconnect in detail including the fabrication of the thin-film VCSEL array, its characterization, thermal management, the fabrication of optical interconnection layer, and the integration of devices on a flexible waveguide film. All the optical components are buried within electrical PCB layers in a fully embedded board level optical interconnect. Therefore, we can save foot prints on the top real estate of the PCB and relieve packaging difficulty reduced by separating fabrication processes. To realize fully embedded board level optical

  4. Atom optics

    International Nuclear Information System (INIS)

    Balykin, V. I.; Jhe, W.

    1999-01-01

    Atom optics, in analogy to neutron and electron optics, deals with the realization of as a traditional elements, such as lenes, mirrors, beam splitters and atom interferometers, as well as a new 'dissipative' elements such as a slower and a cooler, which have no analogy in an another types of optics. Atom optics made the development of atom interferometer with high sensitivity for measurement of acceleration and rotational possible. The practical interest in atom optics lies in the opportunities to create atom microprobe with atom-size resolution and minimum damage of investigated objects. (Cho, G. S.)

  5. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2012-01-01

    Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

  6. New York Canyon Stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Raemy, Bernard

    2012-06-21

    The New York Canyon Stimulation Project was to demonstrate the commercial application of Enhanced Geothermal System techniques in Buena Vista Valley area of Pershing County, Nevada. From October 2009 to early 2012, TGP Development Company aggressively implemented Phase I of Pre-Stimulation and Site/Wellbore readiness. This included: geological studies; water studies and analyses and procurement of initial permits for drilling. Oversubscription of water rights and lack of water needed for implementation of EGS were identified and remained primary obstacles. Despite extended efforts to find alternative solutions, the water supply circumstances could not be overcome and led TGP to determine a "No Go" decision and initiate project termination in April 2012.

  7. Applied optics and optical design

    CERN Document Server

    Conrady, Alexander Eugen

    1957-01-01

    ""For the optical engineer it is an indispensable work."" - Journal, Optical Society of America""As a practical guide this book has no rival."" - Transactions, Optical Society""A noteworthy contribution,"" - Nature (London)Part I covers all ordinary ray-tracing methods, together with the complete theory of primary aberrations and as much of higher aberration as is needed for the design of telescopes, low-power microscopes and simple optical systems. Chapters: Fundamental Equations, Spherical Aberration, Physical Aspect of Optical Images, Chromatic Aberration, Design of Achromatic Object-Glass

  8. Stimulated emission of phonons in an acoustic cavity

    NARCIS (Netherlands)

    Tilstra, Lieuwe Gijsbert

    2001-01-01

    This thesis will present experiments on stimulated emission of phonons in dilute ruby following complete population inversion of the Zeeman-split E(2E) Kramers doublet by selective pulsed optical pumping into its upper component. The resulting phonon avalanches are detected by use of the R1

  9. Optical Properties of Photonic Crystals

    CERN Document Server

    Sakoda, Kazuaki

    2005-01-01

    This is the first comprehensive textbook on the optical properties of photonic crystals. It deals not only with the properties of the radiation modes inside the crystals but also with their peculiar optical response to external fields. A general theory of linear and nonlinear optical response is developed in a clear and detailed fashion using the Green's function method. The symmetry of the eigenmodes is treated systematically using group theory to show how it affects the optical properties of photonic crystals. Important recent developments such as the enhancement of stimulated emission, second harmonic generation, quadrature-phase squeezing, and low-threshold lasing are also treated in detail and made understandable. Numerical methods are also emphasized. Thus this book provides both an introduction for graduate and undergraduate students and also key information for researchers in this field. This second edition has been updated and includes a new chapter on superfluorescence.

  10. stimulated BV2 Microglial

    African Journals Online (AJOL)

    2012-03-26

    Mar 26, 2012 ... (PGE2) as well as their regulatory genes such as inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-. 2), in LPS-stimulated ... mediated NF-κB activity. Keywords: Myelophycus caespitosus, Nitric oxide, Prostaglandin E2, Nuclear factor-κB. ..... induced by hypoxia and endotoxin. J Immunol. 2000 ...

  11. Brain stimulation in migraine.

    Science.gov (United States)

    Brighina, Filippo; Cosentino, Giuseppe; Fierro, Brigida

    2013-01-01

    Migraine is a very prevalent disease with great individual disability and socioeconomic burden. Despite intensive research effort in recent years, the etiopathogenesis of the disease remains to be elucidated. Recently, much importance has been given to mechanisms underlying the cortical excitability that has been suggested to be dysfunctional in migraine. In recent years, noninvasive brain stimulation techniques based on magnetic fields (transcranial magnetic stimulation, TMS) and on direct electrical currents (transcranial direct current stimulation, tDCS) have been shown to be safe and effective tools to explore the issue of cortical excitability, activation, and plasticity in migraine. Moreover, TMS, repetitive TMS (rTMS), and tDCS, thanks to their ability to interfere with and/or modulate cortical activity inducing plastic, persistent effects, have been also explored as potential therapeutic approaches, opening an interesting perspective for noninvasive neurostimulation for both symptomatic and preventive treatment of migraine and other types of headache. In this chapter we critically review evidence regarding the role of noninvasive brain stimulation in the pathophysiology and treatment of migraine, delineating the advantages and limits of these techniques together with potential development and future application. © 2013 Elsevier B.V. All rights reserved.

  12. Stimulated Brillouin Cavity Optomechanics in Liquid Droplets

    Science.gov (United States)

    Giorgini, A.; Avino, S.; Malara, P.; De Natale, P.; Yannai, M.; Carmon, T.; Gagliardi, G.

    2018-02-01

    Liquid droplets are ubiquitous in nature wherein surface tension shapes them into perfect spheres with atomic-scale smooth surfaces. Here, we use stable droplets that cohost equatorial acoustical and optical resonances phase matched to enable the exchange of energy and momentum between sound and light. Relying on free-space laser excitation of multiple whispering-gallery modes, we harness a triple-resonant forward Brillouin scattering to stimulate optomechanical surface waves. Nonlinear amplification of droplet vibrations in the 60-70 MHz range is realized with spectral narrowing beyond the limit of material loss, thereby activating the droplet as hypersound-laser emitter.

  13. Optics Express

    OpenAIRE

    Poon, Ting-Chung; Doh, K. B.

    2007-01-01

    The Hilbert transform as been investigated abundantly in coherent imaging. To the best of our knowledge, it is for the first time investigated in the context of incoherent imaging. We present a two-pupil optical heterodyne scanning system and analyze mathematically the design of its two pupils such that the optical system can perform the Hilbert transform on incoherent objects. Computer simulations of the idea clarify the theoretical results. (c) 2007 Optical Society of America.

  14. Optical electronics

    CERN Document Server

    Yariv, Amnon

    1991-01-01

    This classic text introduces engineering students to the first principles of major phenomena and devices of optoelectronics and optical communication technology. Yariv's "first principles" approach employs real-life examples and extensive problems. The text includes separate chapters on quantum well and semiconductor lasers, as well as phase conjugation and its applications. Optical fiber amplification, signal and noise considerations in optical fiber systems, laser arrays and distributed feedback lasers all are covered extensively in major sections within chapters.

  15. Light scattering changes follow evoked potentials from hippocampal Schaeffer collateral stimulation

    DEFF Research Database (Denmark)

    Rector, D M; Poe, G R; Kristensen, Morten Pilgaard

    1997-01-01

    We assessed relationships of evoked electrical and light scattering changes from cat dorsal hippocampus following Schaeffer collateral stimulation. Under anesthesia, eight stimulating electrodes were placed in the left hippocampal CA field and an optic probe, coupled to a photodiode or a charge...

  16. Optical Computing With Nonlinear Optics

    Science.gov (United States)

    Khitrova, Galina; Gibbs, Hyatt; Peyghambarian, Nasser

    1987-01-01

    Nonlinear optics is becoming a new thrust in the field of optical computing and signal processing.14 Optical nonlinearity makes the device's transmission intensity dependent, so one can obtain the thresholding needed for logic decisionmaking. Thresholding is essential to digital optical computing, neural nets, and associative memories. GaAs etalons exhibit many of the characteristics desirable for the nonlinear devices including high speed (picosecond) and diode-laser compatability. However, demonstrations of the use of nonlinear decisionmaking for optical computing have used ZnS or ZnSe interference filters. They are slow (millisecond), but they can be used with the visible 514.5-nm output of an argon laser. We have used such filters to demonstrate all-optical logic operations, one-bit addition by symbolic substitution, and recognition of a three-spot pattern in an arbitrary 2 x 8 array of input beams. The application to associative memories is under study.

  17. Polarization Optics

    OpenAIRE

    Fressengeas, Nicolas

    2010-01-01

    The physics of polarization optics *Polarized light propagation *Partially polarized light; DEA; After a brief introduction to polarization optics, this lecture reviews the basic formalisms for dealing with it: Jones Calculus for totally polarized light and Stokes parameters associated to Mueller Calculus for partially polarized light.

  18. Optical Computing

    Indian Academy of Sciences (India)

    Integration (VLSI) technology with smaller device dimensions and greater complexity. The smallest .... on a chip, much less than what was mentioned earlier (optical integration is still in its infancy compared to electronics). ..... Optical tunnel devices are under continuous development varying from small caliber endoscopes to ...

  19. Optical Computing

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 6. Optical Computing - Optical Components and Storage Systems. Debabrata Goswami. General Article Volume 8 Issue 6 June 2003 pp 56-71. Fulltext. Click here to view fulltext PDF. Permanent link:

  20. Dorsal column stimulator applications

    OpenAIRE

    Yampolsky, Claudio; Hem, Santiago; Bendersky, Damián

    2012-01-01

    Background: Spinal cord stimulation (SCS) has been used to treat neuropathic pain since 1967. Following that, technological progress, among other advances, helped SCS become an effective tool to reduce pain. Methods: This article is a non-systematic review of the mechanism of action, indications, results, programming parameters, complications, and cost-effectiveness of SCS. Results: In spite of the existence of several studies that try to prove the mechanism of action of SCS, it still remains...

  1. Grating stimulated echo

    International Nuclear Information System (INIS)

    Dubetsky, B.; Berman, P.R.; Sleator, T.

    1992-01-01

    A theory of a grating simulated echo (GTE) is developed. The GSE involves the sequential excitation of atoms by two counterpropagating traveling waves, a standing wave, and a third traveling wave. It is shown that the echo signal is very sensitive to small changes in atomic velocity, much more sensitive than the normal stimulated echo. Use of the GSE as a collisional probe or accelerometer is discussed

  2. Optical biosensors.

    Science.gov (United States)

    Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

    2016-06-30

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  3. Visual stimulation, H-1 MR spectroscopy and fMRI of the human visual pathways

    NARCIS (Netherlands)

    Boucard, CC; Mostert, JP; Cornelissen, FW; De Keyser, J; Oudkerk, M; Sijens, PE

    The purpose was to assess changes in lactate content and other brain metabolites under visual stimulation in optical chiasm, optic radiations and occipital cortex using multiple voxel MR spectroscopy (MRS). H-1 chemical shift imaging (CSI) examinations of transverse planes centered to include the

  4. Low intensity transcranial electric stimulation

    DEFF Research Database (Denmark)

    Antal, A.; Alekseichuk, I.; Bikson, M.

    2017-01-01

    Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears...

  5. Physiological aspects of paired stimulation

    NARCIS (Netherlands)

    Meijler, F.L.; Durrer, D.

    1965-01-01

    In this paper some physiological and clinical aspects of paired stimulation are discussed. I) The augmenting effect of paired stimulation on rnyocardial contractility is due to potentiation (increase in speed of restitution) and fusion of two contractions. 2) While using paired stimulation the

  6. Fiber optic coupled optical sensor

    Science.gov (United States)

    Fleming, Kevin J.

    2001-01-01

    A displacement sensor includes a first optical fiber for radiating light to a target, and a second optical fiber for receiving light from the target. The end of the first fiber is adjacent and not axially aligned with the second fiber end. A lens focuses light from the first fiber onto the target and light from the target onto the second fiber.

  7. A brush stimulator for functional brain imaging.

    Science.gov (United States)

    Jousmäki, V; Nishitani, N; Hari, R

    2007-12-01

    To describe a novel non-magnetic hand-held device to stimulate various parts of the skin and to evaluate its performance in magnetoencephalographic (MEG) recordings. The hand-held part of the device consists of an optic fiber bundle that forms a small brush. Half of the fibers emit modulated red light and the other half detect the reflected light from the skin so that the brush-to-skin contact is detected by means of reflectance. Light tapping of the back of the hand at the innervation area of the radial nerve elicited clear responses in all 10 subjects studied, with the main deflections peaking 40-70 ms after the stimulus. The earliest responses, obtained with a higher number of averaged trials, peaked 27-28 ms after the tap to the left hand dorsum. Source analysis of the MEG signals indicated neuronal sources at the primary somatosensory (SI) cortex, with a clear somatotopical order for face vs. hand. The device seems feasible for both MEG and functional magnetic resonance imaging experiments to address functional anatomy of the human somatosensory system with a real-life like stimulation. Non-magnetic and artefact-free tactile stimulator with a selective stimulus offers new possibilities for experimental designs to study the human mechanoreceptor system.

  8. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  9. Comparison of cortical responses to the activation of retina by visual stimulation and transcorneal electrical stimulation.

    Science.gov (United States)

    Sun, Pengcheng; Li, Heng; Lu, Zhuofan; Su, Xiaofan; Ma, Zengguang; Chen, Jianpin; Li, Liming; Zhou, Chuanqing; Chen, Yao; Chai, Xinyu

    2018-02-21

    Electrical stimulation has been widely used in many ophthalmic diseases to modulate neuronal activities or restore partial visual function. Due to the different processing pathways and mechanisms, responses to visual and electrical stimulation in the primary visual cortex and higher visual areas might be different. This differences would shed some light on the properties of cortical responses evoked by electrical stimulation. This study's goal was to directly compare the cortical responses evoked by visual and electrical stimulation and investigate the cortical processing of visual information and extrinsic electrical signal. Optical imaging of intrinsic signals (OIS) was used to probe the cortical hemodynamic responses in 11 cats. Transcorneal electrical stimulation (TES) through an ERG-jet contact lens electrode was used to activate visual cortices. Full-field and peripheral drifting gratings were used as the visual stimuli. The response latency evoked by TES was shorter than that responding to visual stimulation (VS). Cortical responses evoked by VS were retinotopically organized, which was consistent with previous studies. On the other hand, the cortical region activated by TES was preferentially located in the secondary visual cortex (Area 18), while the primary visual cortex (Area 17) was activated by a higher current intensity. Compared with the full-field VS, the cortical response in Area 18 to TES with a current intensity above 1.2 mA was significantly stronger. According to our results, we provided some evidence that the cortical processing of TES was influenced by the distribution of the electrical field in the retina and the activating threshold of different retinal ganglion cells. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Spinal Cord Stimulation

    DEFF Research Database (Denmark)

    Meier, Kaare

    2014-01-01

    Spinal cord stimulation (SCS) is a surgical treatment for chronic neuropathic pain that is refractory to other treatment. Originally described by Shealy et al. in 1967(1), it is used to treat a range of conditions such as complex regional pain syndrome (CRPS I)(2), angina pectoris(3), radicular...... pain after failed back surgery syndrome (FBSS)(4), pain due to peripheral nerve injury, stump pain(5), peripheral vascular disease(6) and diabetic neuropathy(7,8); whereas phantom pain(9), postherpetic neuralgia(10), chronic visceral pain(11), and pain after partial spinal cord injury(12) remain more...

  11. Integrated optics

    International Nuclear Information System (INIS)

    Jekowski, J.; Aeby, I.

    1979-01-01

    The purpose of the R and D effort is to establish a baseline technology in integrated optic techniques within the EMG. Significant investment presently being made by industry in this area indicates that this technology may offer an alternative solution for high speed digital data acquisition and transmission. The objectives of this year's integrated optics program were three-fold: (1) to establish a literature search and maintain industry contacts in an attempt to make the needs of the Weapons Test Program known; (2) to assist the Las Vegas Hybrid facility in establising integrated optic fabrication techniques for their new Thin Film Laboratory; and (3) to conduct basic experiments at Los Alamos in the construction of photolithograhicaly etched plastic film devices. The report describes the successful completion of preliminary investigations into photolithographic techniques and continuing investigations into newly announced integrated optic techniques and devices that would be applicable to the weapons test program

  12. Optical Spectroscopy

    DEFF Research Database (Denmark)

    Thyrhaug, Erling

    The work presented in this thesis is broadly concerned with how complexation reactions and molecular motion can be characterized with the standard techniques in optical spectroscopy. The thesis aims to show a relatively broad range of methods for probing physico-chemical properties in fluorophore...... containing systems and are characterized using techniques in optical spectroscopy. Of the standard techniques in optical spectroscopy, particular attention has been paid to those based on time-resolved measurements and polarization, which is reflected in the experiment design in the projects. Not all...... reactions by optical spectroscopy. In project 1 simple steady-state absorption and fluorescence spectroscopy is used to determine the stoichiometries and equilibrium constants in the inclusion complex formation between cyclodextrins and derivatives of the water-insoluble oligo(phenylene vinylene) in aqueous...

  13. Stimulation-induced optical signals in rat spinal cord slices

    Czech Academy of Sciences Publication Activity Database

    Kubinová, Šárka; Vargová, Lýdia; Syková, Eva

    2002-01-01

    Roč. 1, - (2002), s. 34 ISSN 0894-1491. [European Meeting on Glial Cell Function in Health and Disease. Rome - Italy, 21.05.2002-25.05.2002] R&D Projects: GA MŠk LN00A065 Institutional research plan: CEZ:AV0Z5039906; CEZ:MSM 111300004; CEZ:MSM 5011112 Keywords : spinal cord Subject RIV: FH - Neurology Impact factor: 4.600, year: 2002

  14. Towards multi-exponential analysis in optically stimulated luminescence

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Hansen, Per Christian

    2010-01-01

    analysis of the performance and stability of two models, the decay and peak form, and we consider different transformation methods for obtaining the peak form. For the numerical computations we use a nonlinear least squares (NLS) method and a method based on a first-kind Fredholm integral equation (FIE......). Our analysis uses artificial data with three components (seven parameters including the background) and ten different levels of background, both the signal and the background contain Poisson distributed noise. Parameters derived using both models are acceptable (statistically consistent...

  15. Quantum optics

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund

    2013-01-01

    Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves.......Further sensitivity improvements are required before advanced optical interferometers will be able to measure gravitational waves. A team has now shown that introducing quantum squeezing of light may help to detect these elusive waves....

  16. Ocean optics

    Energy Technology Data Exchange (ETDEWEB)

    Spinard, R.W.; Carder, K.L.; Perry, M.J.

    1994-12-31

    This volume is the twenty fifth in the series of Oxford Monographs in Geology and Geophysics. The propagation off light in the hydra-atmosphere systems is governed by the integral-differential Radiative Transfer Equation (RTE). Closure and inversion are the most common techniques in optical oceanography to understand the most basic principles of natural variability. Three types of closure are dealt with: scale closure, experimental closure, and instrument closure. The subject is well introduced by Spinard et al. in the Preface while Howard Gordon in Chapter 1 provides an in-depth introduction to the RTE and its inherent problems. Inherent and apparent optical properties are dealt with in Chapter 2 by John Kirk and the realities of optical closure are presented in the following chapter by Ronald Zaneveld. The balance of the papers in this volume is quite varied. The early papers deal in a very mathematical manner with the basics of radiative transfer and the relationship between inherent and optical properties. Polarization of sea water is discussed in a chapter that contains a chronological listing of discoveries in polarization, starting at about 1000 AD with the discovery of dichroic properties of crystals by the Vikings and ending with the demonstration of polarotaxis in certain marine organisms by Waterman in 1972. Chapter 12 on Raman scattering in pure water and the pattern recognition techniques presented in Chapter 13 on the optical effects of large particles may be of relevance to fields outside ocean optics.

  17. A distributed current stimulator ASIC for high density neural stimulation.

    Science.gov (United States)

    Jeong Hoan Park; Chaebin Kim; Seung-Hee Ahn; Tae Mok Gwon; Joonsoo Jeong; Sang Beom Jun; Sung June Kim

    2016-08-01

    This paper presents a novel distributed neural stimulator scheme. Instead of a single stimulator ASIC in the package, multiple ASICs are embedded at each electrode site for stimulation with a high density electrode array. This distributed architecture enables the simplification of wiring between electrodes and stimulator ASIC that otherwise could become too complex as the number of electrode increases. The individual ASIC chip is designed to have a shared data bus that independently controls multiple stimulating channels. Therefore, the number of metal lines is determined by the distributed ASICs, not by the channel number. The function of current steering is also implemented within each ASIC in order to increase the effective number of channels via pseudo channel stimulation. Therefore, the chip area can be used more efficiently. The designed chip was fabricated with area of 0.3 mm2 using 0.18 μm BCDMOS process, and the bench-top test was also conducted to validate chip performance.

  18. Transcranial brain stimulation: closing the loop between brain and stimulation

    DEFF Research Database (Denmark)

    Karabanov, Anke; Thielscher, Axel; Siebner, Hartwig Roman

    2016-01-01

    PURPOSE OF REVIEW: To discuss recent strategies for boosting the efficacy of noninvasive transcranial brain stimulation to improve human brain function. RECENT FINDINGS: Recent research exposed substantial intra- and inter-individual variability in response to plasticity-inducing transcranial brain...... transcranial brain stimulation. Priming interventions or paired associative stimulation can be used to ‘standardize’ the brain-state and hereby, homogenize the group response to stimulation. Neuroanatomical and neurochemical profiling based on magnetic resonance imaging and spectroscopy can capture trait......-related and state-related variability. Fluctuations in brain-states can be traced online with functional brain imaging and inform the timing or other settings of transcranial brain stimulation. State-informed open-loop stimulation is aligned to the expression of a predefined brain state, according to prespecified...

  19. Analysis of laser-induced heating in optical neuronal guidance

    DEFF Research Database (Denmark)

    Ebbesen, Christian L.; Bruus, Henrik

    2012-01-01

    Recently, it has been shown that it is possible to control the growth direction of neuronal growth cones by stimulation with weak laser light; an effect dubbed optical neuronal guidance. The effect exists for a broad range of laser wavelengths, spot sizes, spot intensities, optical intensity...

  20. Distributed stimulation increases force elicited with functional electrical stimulation

    Science.gov (United States)

    Buckmire, Alie J.; Lockwood, Danielle R.; Doane, Cynthia J.; Fuglevand, Andrew J.

    2018-04-01

    Objective. The maximum muscle forces that can be evoked using functional electrical stimulation (FES) are relatively modest. The reason for this weakness is not fully understood but could be partly related to the widespread distribution of motor nerve branches within muscle. As such, a single stimulating electrode (as is conventionally used) may be incapable of activating the entire array of motor axons supplying a muscle. Therefore, the objective of this study was to determine whether stimulating a muscle with more than one source of current could boost force above that achievable with a single source. Approach. We compared the maximum isometric forces that could be evoked in the anterior deltoid of anesthetized monkeys using one or two intramuscular electrodes. We also evaluated whether temporally interleaved stimulation between two electrodes might reduce fatigue during prolonged activity compared to synchronized stimulation through two electrodes. Main results. We found that dual electrode stimulation consistently produced greater force (~50% greater on average) than maximal stimulation with single electrodes. No differences, however, were found in the fatigue responses using interleaved versus synchronized stimulation. Significance. It seems reasonable to consider using multi-electrode stimulation to augment the force-generating capacity of muscles and thereby increase the utility of FES systems.

  1. Brain stimulation for intractable epilepsy: Anterior thalamus and responsive stimulation

    Directory of Open Access Journals (Sweden)

    Vibhor Krishna

    2014-01-01

    Full Text Available Despite medications, resective surgery, and vagal nerve stimulation, some patients with epilepsy continue to have seizures. In these patients, other approaches are urgently needed. The biological basis of stimulation of anterior thalamic nucleus and epileptogenic focus is presented. Results from two large randomized controlled trials Stimulation of Anterior Nucleus of Thalamus for Epilepsy (SANTE and Neuropace pivotal trial are discussed. Neuromodulation provides effective treatment for a select group of refractory epilepsy patients. Future investigations into the mechanism underlying ′response′ to brain stimulation are desired.

  2. QUANTUM OPTICS. Universal linear optics.

    Science.gov (United States)

    Carolan, Jacques; Harrold, Christopher; Sparrow, Chris; Martín-López, Enrique; Russell, Nicholas J; Silverstone, Joshua W; Shadbolt, Peter J; Matsuda, Nobuyuki; Oguma, Manabu; Itoh, Mikitaka; Marshall, Graham D; Thompson, Mark G; Matthews, Jonathan C F; Hashimoto, Toshikazu; O'Brien, Jeremy L; Laing, Anthony

    2015-08-14

    Linear optics underpins fundamental tests of quantum mechanics and quantum technologies. We demonstrate a single reprogrammable optical circuit that is sufficient to implement all possible linear optical protocols up to the size of that circuit. Our six-mode universal system consists of a cascade of 15 Mach-Zehnder interferometers with 30 thermo-optic phase shifters integrated into a single photonic chip that is electrically and optically interfaced for arbitrary setting of all phase shifters, input of up to six photons, and their measurement with a 12-single-photon detector system. We programmed this system to implement heralded quantum logic and entangling gates, boson sampling with verification tests, and six-dimensional complex Hadamards. We implemented 100 Haar random unitaries with an average fidelity of 0.999 ± 0.001. Our system can be rapidly reprogrammed to implement these and any other linear optical protocol, pointing the way to applications across fundamental science and quantum technologies. Copyright © 2015, American Association for the Advancement of Science.

  3. Vagus Nerve Stimulation.

    Science.gov (United States)

    Ekmekçi, Hakan; Kaptan, Hülagu

    2017-06-15

    The vagus nerve stimulation (VNS) is an approach mainly used in cases of intractable epilepsy despite all the efforts. Also, its benefits have been shown in severe cases of depression resistant to typical treatment. The aim of this study was to present current knowledge of vagus nerve stimulation. A new value has emerged just at this stage: VNS aiming the ideal treatment with new hopes. It is based on the placement of a programmable generator on the chest wall. Electric signals from the generator are transmitted to the left vagus nerve through the connection cable. Control on the cerebral bioelectrical activity can be achieved by way of these signal sent from there in an effort for controlling the epileptic discharges. The rate of satisfactory and permanent treatment in epilepsy with monotherapy is around 50%. This rate will increase by one-quarters (25%) with polytherapy. However, there is a patient group roughly constituting one-thirds of this population, and this group remains unresponsive or refractory to all the therapies and combined regimes. The more the number of drugs used, the more chaos and side effects are observed. The anti-epileptic drugs (AEDs) used will have side effects on both the brain and the systemic organs. Cerebral resection surgery can be required in some patients. The most commonly encountered epilepsy type is the partial one, and the possibility of benefiting from invasive procedures is limited in most patients of this type. Selective amygdala-hippocampus surgery is a rising value in complex partial seizures. Therefore, as epilepsy surgery can be performed in very limited numbers and rather developed centres, success can also be achieved in limited numbers of patients. The common ground for all the surgical procedures is the target of preservation of memory, learning, speaking, temper and executive functions as well as obtaining a good control on seizures. However, the action mechanism of VNS is still not exactly known. On the other hand

  4. Optical imaging of fast, dynamic neurophysiological function.

    Energy Technology Data Exchange (ETDEWEB)

    Rector, D. M. (David M.); Carter, K. M. (Kathleen M.); Yao, X. (Xincheng); George, J. S. (John S.)

    2002-01-01

    Fast evoked responses were imaged from rat dorsal medulla and whisker barrel cortex. To investigate the biophysical mechanisms involved, fast optical responses associated with isolated crustacean nerve stimulation were recorded using birefringence and scattered light. Such studies allow optimization of non-invasive imaging techniques being developed for use in humans.

  5. Engagement sensitive visual stimulation

    Directory of Open Access Journals (Sweden)

    Deepesh Kumar

    2016-06-01

    Full Text Available Stroke is one of leading cause of death and disability worldwide. Early detection during golden hour and treatment of individual neurological dysfunction in stroke using easy-to-access biomarkers based on a simple-to-use, cost-effective, clinically-valid screening tool can bring a paradigm shift in healthcare, both urban and rural. In our research we have designed a quantitative automatic home-based oculomotor assessment tool that can play an important complementary role in prognosis of neurological disorders like stroke for the neurologist. Once the patient has been screened for stroke, the next step is to design proper rehabilitation platform to alleviate the disability. In addition to the screening platform, in our research, we work in designing virtual reality based rehabilitation exercise platform that has the potential to deliver visual stimulation and in turn contribute to improving one’s performance.

  6. Motor stimulation with interferential currents.

    Science.gov (United States)

    DE Domenico, G G; Strauss, G R

    1985-01-01

    The stimulation of motor nerves to produce muscle contraction in normally innervated muscles is a long established part of orthodox physiotherapy. Recently however, a revival of interest in the area has occurred, particularly in the U.S.A. Recent research has indicated that such stimulation can improve muscle strength, reduce muscle spasm and modulate spasticity, in addition to the more usual re-educative role of electrical stimulation. The concept of functional electrical stimulation (F.E.S.) seems destined to become an integral part of many programmes for the neurologically handicapped patient. This paper describes the technique of motor stimulation using interferential currents. The stimulating parameters and electrode placement are considered, along with a detailed explanation of the pre-modulated system of electrode arrangement. Copyright © 1985 Australian Physiotherapy Association. Published by . All rights reserved.

  7. Semiconductor Optics

    CERN Document Server

    Klingshirn, Claus F

    2012-01-01

    This updated and enlarged new edition of Semiconductor Optics provides an introduction to and an overview of semiconductor optics from the IR through the visible to the UV, including linear and nonlinear optical properties, dynamics, magneto and electrooptics, high-excitation effects and laser processes, some applications, experimental techniques and group theory. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered extend from physics to materials science and optoelectronics. Significantly updated chapters add coverage of current topics such as electron hole plasma, Bose condensation of excitons and meta materials. Over 120 problems, chapter introductions and a detailed index make it the key textbook for graduate students in physics. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered ...

  8. Optical memory

    Science.gov (United States)

    Mao, Samuel S; Zhang, Yanfeng

    2013-07-02

    Optical memory comprising: a semiconductor wire, a first electrode, a second electrode, a light source, a means for producing a first voltage at the first electrode, a means for producing a second voltage at the second electrode, and a means for determining the presence of an electrical voltage across the first electrode and the second electrode exceeding a predefined voltage. The first voltage, preferably less than 0 volts, different from said second voltage. The semiconductor wire is optically transparent and has a bandgap less than the energy produced by the light source. The light source is optically connected to the semiconductor wire. The first electrode and the second electrode are electrically insulated from each other and said semiconductor wire.

  9. Super-resolution optical telescopes with local light diffraction shrinkage

    OpenAIRE

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-01-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found ...

  10. Reflective optics

    CERN Document Server

    Korsch, Dietrich

    1991-01-01

    This is the first book dedicated exclusively to all-reflective imaging systems. It is a teaching tool as well as a practical design tool for anyone who specializes in optics, particularly for those interested in telescopes, infrared, and grazing-incidence systems. The first part of the book describes a unified geometric optical theory of all-reflective imaging systems (from near-normal to grazing incidence) developed from basic principles. The second part discusses correction methods and a multitude of closed-form solutions of well-corrected systems, supplemented with many conventional and unc

  11. Optical dosimeter

    International Nuclear Information System (INIS)

    Drukaroff, I.; Fishman, R.

    1984-01-01

    A reflecting optical dosimeter is a thin block of optical material having an input light pipe at one corner and an output light pipe at another corner, arranged so that the light path includes several reflections off the edges of the block to thereby greatly extend its length. In a preferred embodiment, one corner of the block is formed at an angle so that after the light is reflected several times between two opposite edges, it is then reflected several more times between the other two edges

  12. Statistical optics

    CERN Document Server

    Goodman, Joseph W

    2015-01-01

    This book discusses statistical methods that are useful for treating problems in modern optics, and the application of these methods to solving a variety of such problems This book covers a variety of statistical problems in optics, including both theory and applications.  The text covers the necessary background in statistics, statistical properties of light waves of various types, the theory of partial coherence and its applications, imaging with partially coherent light, atmospheric degradations of images, and noise limitations in the detection of light. New topics have been introduced i

  13. Quantum optics

    International Nuclear Information System (INIS)

    Flytzanis, C.

    1988-01-01

    The 1988 progress report of the Quantum Optics laboratory (Polytechnic School, France) is presented. The research program is focused on the behavior of dense and dilute materials submitted to short and high-intensity light radiation fields. Nonlinear optics techniques, with time and spatial resolution, are developed. An important research activity concerns the investigations on the interactions between the photon beams and the inhomogeneous or composite materials, as well as the artificial microstructures. In the processes involving molecular beams and surfaces, the research works on the photophysics of surfaces and the molecule-surface interactions, are included [fr

  14. Visual stimulation, {sup 1}H MR spectroscopy and fMRI of the human visual pathways

    Energy Technology Data Exchange (ETDEWEB)

    Boucard, Christine C.; Cornelissen, Frans W. [University of Groningen, Laboratory for Experimental Ophthalmology, Postbus 30001, Groningen (Netherlands); University of Groningen, BCN Neuro-imaging Center, Postbus 196, Groningen (Netherlands); Mostert, Jop P.; Keyser, Jacques De [University Hospital Groningen, Department of Neurology, Groningen (Netherlands); Oudkerk, Matthijs; Sijens, Paul E. [University Hospital Groningen, Department of Radiology, Groningen (Netherlands)

    2005-01-01

    The purpose was to assess changes in lactate content and other brain metabolites under visual stimulation in optical chiasm, optic radiations and occipital cortex using multiple voxel MR spectroscopy (MRS). {sup 1}H chemical shift imaging (CSI) examinations of transverse planes centered to include the above structures were performed in four subjects at an echo time of 135 ms. Functional MRI (fMRI) was used to confirm the presence of activity in the visual cortex during the visual stimulation. Spectral maps of optical chiasm were of poor quality due to field disturbances caused by nearby large blood vessels and/or eye movements. The optic radiations and the occipital lobe did not show any significant MR spectral change upon visual stimulation, i.e., the peak areas of inositol, choline, creatine, glutamate and N-acetylaspartate were not affected. Reproducible lactate signals were not observed. fMRI confirmed the presence of strong activations in stimulated visual cortex. Prolonged visual stimulation did not cause significant changes in MR spectra. Any signal observed near the 1.33 ppm resonance frequency of the lactate methyl-group was artifactual, originating from lipid signals from outside the volume of interest (VOI). Previous claims about changes in lactate levels in the visual cortex upon visual stimulation may have been based on such erroneous observations. (orig.)

  15. Fluorescence microscopy with diffraction resolution barrier broken by stimulated emission

    OpenAIRE

    Klar, Thomas A.; Jakobs, Stefan; Dyba, Marcus; Egner, Alexander; Hell, Stefan W.

    2000-01-01

    The diffraction barrier responsible for a finite focal spot size and limited resolution in far-field fluorescence microscopy has been fundamentally broken. This is accomplished by quenching excited organic molecules at the rim of the focal spot through stimulated emission. Along the optic axis, the spot size was reduced by up to 6 times beyond the diffraction barrier. The simultaneous 2-fold improvement in the radial direction rendered a nearly spherical fluorescence spot with a diameter of 9...

  16. Simulation of morphologically structured photo-thermal neural stimulation

    Science.gov (United States)

    Weissler, Y.; Farah, N.; Shoham, S.

    2017-10-01

    Objective. Rational design of next-generation techniques for photo-thermal excitation requires the development of tools capable of modeling the effects of spatially- and temporally-dependent temperature distribution on cellular neuronal structures. Approach. We present a new computer simulation tool for predicting the effects of arbitrary spatiotemporally-structured photo-thermal stimulation on 3D, morphologically realistic neurons. The new simulation tool is based on interfacing two generic platforms, NEURON and MATLAB and is therefore suited for capturing different kinds of stimuli and neural models. Main results. Simulation results are validated using photo-absorber induced neuro-thermal stimulation (PAINTS) empirical results, and advanced features are explored. Significance. The new simulation tool could have an important role in understanding and investigating complex optical stimulation at the single-cell and network levels.

  17. A wireless implantable switched-capacitor based optogenetic stimulating system.

    Science.gov (United States)

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen; Ghovanloo, Maysam

    2014-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments.

  18. A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

    Science.gov (United States)

    Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

    2015-01-01

    This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

  19. Diophantine Optics

    Science.gov (United States)

    Rouan, D.

    2016-09-01

    What I call Diophantine optics is the exploitation in optics of some remarkable algebraic relations between powers of integers. The name comes from Diophantus of Alexandria, a greek mathematician, known as the father of algebra. He studied polynomial equations with integer coefficients and integer solutions, called diophantine equations. Since constructive or destructive interferences are playing with optical path differences which are multiple integer (odd or even) of λ/2 and that the complex amplitude is a highly non-linear function of the optical path difference (or equivalently of the phase), one can understand that any Taylor development of this amplitude implies powers of integers. This is the link with Diophantine equations. We show how, especially in the field of interferometry, remarkable relations between powers of integers can help to solve several problems, such as achromatization of a phase shifter or deep nulling efficiency. It appears that all the research that was conducted in this frame of thinking, relates to the field of detection of exoplanets, a very active domain of astrophysics today.

  20. Optical profilometer

    Science.gov (United States)

    Wieloszyńska, Aleksandra; StrÄ kowski, Marcin

    2016-09-01

    The profilometry plays a huge role in the most fields of science and technology. It allows to measure the profile of the surface with high-resolution. This technique is used in the fields like optic, electronic, medicine, automotive, and much more. The aim of the current work was to design and build optical profilometer based on the interference phenomena. The developed device has been working with He-Ne laser (632.8 nm). The optical parts have been chosen in order to reach the sized 2.0 mm x 1.6 mm of scanning area. The setup of the profilometer is based on Twyman-Green interferometer. Therefore, the phase distribution of the backreflected light from measured surface is recorded. The measurements are carried out with the aid of multiframe algorithms. In this approach we have used the Hariharan algorithm to obtain the exact value of the recorded phase. During tests, which have been carried out in order to check the functionality of the device, the interference patterns have been recoded and processed in order to obtain the 3D profile of measured surface. In this contribution the setup of the optical system, as well as signal processing methods are going to be presented. The brief discussion about the advantages and disadvantages, and usefulness of this approach will be carried out.

  1. Optical fibres

    CERN Multimedia

    1992-01-01

    These optical fibres are used to detect particles passing through in bunches. Made from scintillating material, the fibres glow when a high energy particle passes through them. These detectors are known as spaghetti detectors and are used to measure the energy of particles.

  2. Optical geometry

    International Nuclear Information System (INIS)

    Robinson, I.; Trautman, A.

    1988-01-01

    The geometry of classical physics is Lorentzian; but weaker geometries are often more appropriate: null geodesics and electromagnetic fields, for example, are well known to be objects of conformal geometry. To deal with a single null congruence, or with the radiative electromagnetic fields associated with it, even less is needed: flag geometry for the first, optical geometry, with which this paper is chiefly concerned, for the second. The authors establish a natural one-to-one correspondence between optical geometries, considered locally, and three-dimensional Cauchy-Riemann structures. A number of Lorentzian geometries are shown to be equivalent from the optical point of view. For example the Goedel universe, the Taub-NUT metric and Hauser's twisting null solution have an optical geometry isomorphic to the one underlying the Robinson congruence in Minkowski space. The authors present general results on the problem of lifting a CR structure to a Lorentz manifold and, in particular, to Minkowski space; and exhibit the relevance of the deviation form to this problem

  3. Optical twisters

    DEFF Research Database (Denmark)

    Daria, Vincent R.; Palima, Darwin; Glückstad, Jesper

    2010-01-01

    We describe a diffracting beam with orbital angular momentum (OAM) but with a helical profile in both phase and amplitude components of the beam. This is different from Laguerre-Gaussian (LG) beams where only the phase component has a helical profile. Such profile in LG beams introduces a phase s....... Such beams can be applied to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps for cold atoms and for optical manipulation of microscopic particles....... and linearly scaled towards no phase singularity at the centre of the beam. At the focal volume, we show that our beam forms an intensity distribution that can be accurately described as an "optical twister" as it propagates in the forward direction. Unlike LG beams, an optical twister can have minimal changes...... in radius but with a scalable OAM. Furthermore, we characterize the OAM in terms of its capacity to introduce spiral motion on particles trapped along its orbit. We also show that our "optical twister" maintains a high concentration of photons at the focus even as the topological charge is increased...

  4. Skin optics

    NARCIS (Netherlands)

    van Gemert, M. J.; Jacques, S. L.; Sterenborg, H. J.; Star, W. M.

    1989-01-01

    Quantitative dosimetry in the treatment of skin disorders with (laser) light requires information on propagation of light in the skin related to the optical properties of the individual skin layers. This involves the solution of the integro-differential equation of radiative transfer in a model

  5. Optical metrology

    CERN Document Server

    Gåsvik, Kjell J

    2003-01-01

    New material on computerized optical processes, computerized ray tracing, and the fast Fourier transform, Bibre-Bragg sensors, and temporal phase unwrapping.* New introductory sections to all chapters.* Detailed discussion on lasers and laser principles, including an introduction to radiometry and photometry.* Thorough coverage of the CCD camera.

  6. Optical Computing

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 7. Optical Computing - Research Trends. Debabrata Goswami. General Article Volume 8 Issue 7 July 2003 pp 8-21. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/008/07/0008-0021. Keywords.

  7. Optical Coherence and Quantum Optics

    CERN Document Server

    Mandel, Leonard

    1995-01-01

    This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topi

  8. Optical Magnetometry

    Science.gov (United States)

    Budker, Dmitry; Kimball, Derek F. Jackson

    2013-03-01

    Part I. Principles and Techniques: 1. General principles and characteristics of optical magnetometers D. F. Jackson Kimball, E. B. Alexandrov and D. Budker; 2. Quantum noise in atomic magnetometers M. V. Romalis; 3. Quantum noise, squeezing, and entanglement in radio-frequency optical magnetometers K. Jensen and E. S. Polzik; 4. Mx and Mz magnetometers E. B. Alexandrov and A. K. Vershovskiy; 5. Spin-exchange-relaxation-free (serf) magnetometers I. Savukov and S. J. Seltzer; 6. Optical magnetometry with modulated light D. F. Jackson Kimball, S. Pustelny, V. V. Yashchuk and D. Budker; 7. Microfabricated atomic magnetometers S. Knappe and J. Kitching; 8. Optical magnetometry with nitrogen-vacancy centers in diamond V. M. Acosta, D. Budker, P. R. Hemmer, J. R. Maze and R. L. Walsworth; 9. Magnetometry with cold atoms W. Gawlik and J. M. Higbie; 10. Helium magnetometers R. E. Slocum, D. D. McGregor and A. W. Brown; 11. Surface coatings for atomic magnetometry S. J. Seltzer, M.-A. Bouchiat and M. V. Balabas; 12. Magnetic shielding V. V. Yashchuk, S.-K. Lee and E. Paperno; Part II. Applications: 13. Remote detection magnetometry S. M. Rochester, J. M. Higbie, B. Patton, D. Budker, R. Holzlöhner and D. Bonaccini Calia; 14. Detection of nuclear magnetic resonance with atomic magnetometers M. P. Ledbetter, I. Savukov, S. J. Seltzer and D. Budker; 15. Space magnetometry B. Patton, A. W. Brown, R. E. Slocum and E. J. Smith; 16. Detection of biomagnetic fields A. Ben-Amar Baranga, T. G. Walker and R. T. Wakai; 17. Geophysical applications M. D. Prouty, R. Johnson, I. Hrvoic and A. K. Vershovskiy; Part III. Broader Impact: 18. Tests of fundamental physics with optical magnetometers D. F. Jackson Kimball, S. K. Lamoreaux and T. E. Chupp; 19. Nuclear magnetic resonance gyroscopes E. A. Donley and J. Kitching; 20. Commercial magnetometers and their application D. C. Hovde, M. D. Prouty, I. Hrvoic and R. E. Slocum; Index.

  9. Stimulating Language: Insights from TMS

    Science.gov (United States)

    Devlin, Joseph T.; Watkins, Kate E.

    2007-01-01

    Fifteen years ago, Pascual-Leone and colleagues used transcranial magnetic stimulation (TMS) to investigate speech production in pre-surgical epilepsy patients and in doing so, introduced a novel tool into language research. TMS can be used to non-invasively stimulate a specific cortical region and transiently disrupt information processing. These…

  10. Kinetics of infrared stimulated luminescence from feldspars

    International Nuclear Information System (INIS)

    Jain, M.; Sohbati, R.; Guralnik, B.; Murray, A.S.; Kook, M.; Lapp, T.; Prasad, A.K.; Thomsen, K.J.; Buylaert, J.P.

    2015-01-01

    We extend the localised transition model based on randomly varying recombination distances (Jain et al., 2012) to include Arrhenius analysis and truncated nearest neighbour distributions. The model makes important predictions regarding a) the physical understanding of the linear intercepts in the Arrhenius analysis for localised recombination systems and b) the relationship between charge depletion and shape of the luminescence decay curves; these predictions are successfully tested by experimental investigations. We demonstrate that this model successfully describes the kinetic behaviour, both thermal and optical, of the infrared stimulated luminescence signal from feldspar. Based on the application of this model, it is concluded that different infra-red stimulated luminescence emissions (UV, blue, yellow and far-red) follow the same kinetics, and, therefore, involve participation of the same electron (dosimetric) trap. The differences in thermal stabilities of the different emissions results from differences in number densities of the recombination sites. The results have implications for understanding the mechanism of the far-red emission, and the spatial distributions of recombination sites in feldspar. - Highlights: • Arrhenius analysis of IRSL based on localized transition model (Jain et al., 2012). • Kinetics of IRSL for the different emission bands. • A new analytical description for IRSL. • Demonstrating that feldspar IRSL is consistent with the predictions of the LTM.

  11. Spontaneous and stimulated emission from quasifree electrons

    Science.gov (United States)

    Friedman, A.; Gover, A.; Kurizki, G.; Ruschin, S.; Yariv, A.

    1988-04-01

    This article presents a unified formulation and review of an extensive class of radiation effects and devices based on free or quasifree electrons. The effects and devices reviewed include slow-wave radiators [such as Čerenkov, Smith-Purcell, and TWT (traveling-wave tube) effects and devices], periodic bremsstrahlung radiators [such as undulator radiation, magnetic bremsstrahlung FEL's (free-electron lasers), and coherent bremsstrahlung in the crystal lattice], and transverse-binding radiators [such as the CRM (cyclotron resonance maser) and channeling radiation]. Starting from a general quantum-electrodynamic model, both quantum and classical effects and operating regimes of these radiation devices are described. The article provides a unified physical description of the interaction kinematics, and presents equations for the characterization of spontaneous and stimulated radiative emission in these various effects and devices. Universal relations between the spontaneous and stimulated emission parameters are revealed and shown to be related (in the quantum limit) to Einstein relations for atomic radiators and (in the classical limit) to the relations derived by Madey for magnetic bremsstrahlung FEL for on-axis radiative emission. Examples for the application of the formulation are given, estimating the feasibility of channeling radiation x-ray laser and optical regime Smith-Purcell FEL, and deriving the gain equations of magnetic bremsstrahlung FEL and CRM for arbitrary electron propagation direction, structure (wiggler) axis, and radiative emission angle.

  12. Early-light embryonic stimulation suggests a second route, via gene activation, to cerebral lateralization in vertebrates

    OpenAIRE

    Chiandetti, Cinzia; Galliussi, Jessica; Andrew, Richard J.; Vallortigara, Giorgio

    2013-01-01

    Genetic factors determine the asymmetrical position of vertebrate embryos allowing asymmetric environmental stimulation to shape cerebral lateralization. In birds, late-light stimulation, just before hatching, on the right optic nerve triggers anatomical and functional cerebral asymmetries. However, some brain asymmetries develop in absence of embryonic light stimulation. Furthermore, early-light action affects lateralization in the transparent zebrafish embryos before their visual system is ...

  13. Luminescence properties of porcelain ceramics relevant to restrospective radiation dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Markey, B.G.; Poolton, N.R.J.

    1996-01-01

    When applied to porcelain products, optically stimulated luminescence (OSL) is a potentially viable method for use in dose reconstruction following contamination from nuclear accidents. However, dose sensitivities are highly variable, depending on what type of porcelain is being measured. This ap......When applied to porcelain products, optically stimulated luminescence (OSL) is a potentially viable method for use in dose reconstruction following contamination from nuclear accidents. However, dose sensitivities are highly variable, depending on what type of porcelain is being measured...... to have the highest sensitivities to radiation dose. Moreover, the presence of these phases is easily identifiable by characteristic signatures in the luminescence emission spectra....

  14. LDEF experiment A0034: Atomic oxygen stimulated outgassing

    Science.gov (United States)

    Linton, Roger C.; Kamenetzky, Rachel R.; Reynolds, John M.; Burris, Charles L.

    1992-01-01

    The passive Long Duration Exposure Facility (LDEF) Experiment A0034, 'Atomic Oxygen Stimulated Outgassing', consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge, and for reference, to the relative 'wake' environment of the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of the outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

  15. Vagal nerve stimulation therapy: what is being stimulated?

    Directory of Open Access Journals (Sweden)

    Guy Kember

    Full Text Available Vagal nerve stimulation in cardiac therapy involves delivering electrical current to the vagal sympathetic complex in patients experiencing heart failure. The therapy has shown promise but the mechanisms by which any benefit accrues is not understood. In this paper we model the response to increased levels of stimulation of individual components of the vagal sympathetic complex as a differential activation of each component in the control of heart rate. The model provides insight beyond what is available in the animal experiment in as much as allowing the simultaneous assessment of neuronal activity throughout the cardiac neural axis. The results indicate that there is sensitivity of the neural network to low level subthreshold stimulation. This leads us to propose that the chronic effects of vagal nerve stimulation therapy lie within the indirect pathways that target intrinsic cardiac local circuit neurons because they have the capacity for plasticity.

  16. Electrical stimulation in exercise training

    Science.gov (United States)

    Kroll, Walter

    1994-01-01

    Electrical stimulation has a long history of use in medicine dating back to 46 A.D. when the Roman physician Largus found the electrical discharge of torpedo fishes useful in the treatment of pain produced by headache and gout. A rival Greek physician, Dioscorides, discounted the value of the torpedo fish for headache relief but did recommend its use in the treatment of hemorrhoids. In 1745, the Leyden jar and various sized electrostatic generators were used to treat angina pectoris, epilepsy, hemiplegia, kidney stones, and sciatica. Benjamin Franklin used an electrical device to treat successfully a young woman suffering from convulsive fits. In the late 1800's battery powered hydroelectric baths were used to treat chronic inflammation of the uterus while electrified athletic supporters were advertised for the treatment of male problems. Fortunately, such an amusing early history of the simple beginnings of electrical stimulation did not prevent eventual development of a variety of useful therapeutic and rehabilitative applications of electrical stimulation. Over the centuries electrical stimulation has survived as a modality in the treatment of various medical disorders with its primary application being in the rehabilitation area. Recently, a surge of new interest in electrical stimulation has been kindled by the work of a Russian sport scientist who reported remarkable muscle strength and endurance improvements in elite athletes. Yakov Kots reported his research on electric stimulation and strength improvements in 1977 at a Canadian-Soviet Exchange Symposium held at Concordia University in Montreal. Since then an explosion of new studies has been seen in both sport science and in medicine. Based upon the reported works of Kots and the present surge of new investigations, one could be misled as to the origin of electrical stimulation as a technique to increase muscle strength. As a matter of fact, electric stimulation has been used as a technique to improve

  17. Visual-servoing optical microscopy

    Science.gov (United States)

    Callahan, Daniel E.; Parvin, Bahram

    2009-06-09

    The present invention provides methods and devices for the knowledge-based discovery and optimization of differences between cell types. In particular, the present invention provides visual servoing optical microscopy, as well as analysis methods. The present invention provides means for the close monitoring of hundreds of individual, living cells over time: quantification of dynamic physiological responses in multiple channels; real-time digital image segmentation and analysis; intelligent, repetitive computer-applied cell stress and cell stimulation; and the ability to return to the same field of cells for long-term studies and observation. The present invention further provides means to optimize culture conditions for specific subpopulations of cells.

  18. Resource Letter on Stimulated Inelastic X-ray Scattering at an XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Bruce D.; /SLAC

    2010-09-02

    At sufficient X-ray intensity, stimulated effects in inelastic scattering will become important. These coherent, non-linear optical phenomena may be used to impulsively produce a high degree of collective excitation in, for example, correlated electron materials, suitable for performing ultrafast time-resolved spectroscopy. This Resource Letter collects information on fundamental aspects of stimulated X-ray scattering and evaluates the prospect for successful experiments at a present or future X-ray free electron laser (XFEL) facility.

  19. Dose response of hydrazine - Deproteinated tooth enamel under blue light stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Yuece, Ulkue Rabia, E-mail: ulkuyuce@hotmail.co [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Meric, Niyazi, E-mail: meric@ankara.edu.t [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Atakol, Orhan, E-mail: atakol@science.ankara.edu.t [Ankara University, Science Faculty, Department of Chemistry, 06100, Tandogan - Ankara (Turkey); Yasar, Fusun, E-mail: ab121310@adalet.gov.t [Council of Forensic Medicine, Ankara Branch, Ankara (Turkey)

    2010-08-15

    The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.

  20. Dose response of hydrazine - Deproteinated tooth enamel under blue light stimulation

    International Nuclear Information System (INIS)

    Yuece, Ulkue Rabia; Meric, Niyazi; Atakol, Orhan; Yasar, Fusun

    2010-01-01

    The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.

  1. Acousto-optic-assisted diffuse optical tomography

    NARCIS (Netherlands)

    Bratchenia, A.; Molenaar, Robert; van Leeuwen, Ton; Kooyman, R.P.H.

    2011-01-01

    We introduce and experimentally demonstrate acousto-optic-assisted diffuse optical tomography (DOT) using a holography-based acousto-optic setup. The method is based on probing a scattering medium with a localized acoustical modulation of the phase of the scattered light. The optical properties of

  2. CHIRALITY IN NONLINEAR OPTICS AND OPTICAL SWITCHING

    NARCIS (Netherlands)

    Meijer, E.W.; Feringa, B.L.

    1993-01-01

    Chirality in molecular opto-electronics is limited sofar to the use of optically active liquid crystals and a number of optical phenomena are related to the helical macroscopic structure obtained by using one enantiomer, only. In this paper, the use of chirality in nonlinear optics and optical

  3. Fiber-based tissue identification for electrode placement in deep brain stimulation neurosurgery (Conference Presentation)

    Science.gov (United States)

    DePaoli, Damon T.; Lapointe, Nicolas; Goetz, Laurent; Parent, Martin; Prudhomme, Michel; Cantin, Léo.; Galstian, Tigran; Messaddeq, Younès.; Côté, Daniel C.

    2016-03-01

    Deep brain stimulation's effectiveness relies on the ability of the stimulating electrode to be properly placed within a specific target area of the brain. Optical guidance techniques that can increase the accuracy of the procedure, without causing any additional harm, are therefore of great interest. We have designed a cheap optical fiber-based device that is small enough to be placed within commercially available DBS stimulating electrodes' hollow cores and that is capable of sensing biological information from the surrounding tissue, using low power white light. With this probe we have shown the ability to distinguish white and grey matter as well as blood vessels, in vitro, in human brain samples and in vivo, in rats. We have also repeated the in vitro procedure with the probe inserted in a DBS stimulating electrode and found the results were in good agreement. We are currently validating a second fiber optic device, with micro-optical components, that will result in label free, molecular level sensing capabilities, using CARS spectroscopy. The final objective will be to use this data in real time, during deep brain stimulation neurosurgery, to increase the safety and accuracy of the procedure.

  4. Noninvasive Stimulation of the Human Brain

    DEFF Research Database (Denmark)

    Di Lazzaro, Vincenzo; Rothwell, John; Capogna, Marco

    2017-01-01

    Noninvasive brain stimulation methods, such as transcranial electric stimulation and transcranial magnetic stimulation are widely used tools for both basic research and clinical applications. However, the cortical circuits underlying their effects are poorly defined. Here we review the current...

  5. Enteral feeding without pancreatic stimulation

    DEFF Research Database (Denmark)

    Kaushik, Neeraj; Pietraszewski, Marie; Holst, Jens Juul

    2005-01-01

    .5 g protein/kg ideal body weight/d. Plasma gut peptide responses were monitored in 15 subjects. RESULTS: In comparison with basal fasting trypsin secretion rates (mean = 134 [standard error = 22] U/h), duodenal feeding with the polymeric and elemental formulae stimulated trypsin secretion (mean = 408...... in enteral feeding without pancreatic stimulation, with particular reference to trypsin, because the avoidance of trypsin stimulation may optimize enteral feeding in acute pancreatitis. METHODS: The pancreatic secretory responses to feeding were studied in 36 healthy volunteers by standard double...... [standard error = 51] U/h; P standard error = 34] U/h) and mid-distal jejunal (mean = 119 [standard error = 16] U/h) did not. Stimulation was associated with an increase in plasma cholecystokinin, whereas distal jejunal feeding resulted in an increase...

  6. Demultiplexer circuit for neural stimulation

    Science.gov (United States)

    Wessendorf, Kurt O; Okandan, Murat; Pearson, Sean

    2012-10-09

    A demultiplexer circuit is disclosed which can be used with a conventional neural stimulator to extend the number of electrodes which can be activated. The demultiplexer circuit, which is formed on a semiconductor substrate containing a power supply that provides all the dc electrical power for operation of the circuit, includes digital latches that receive and store addressing information from the neural stimulator one bit at a time. This addressing information is used to program one or more 1:2.sup.N demultiplexers in the demultiplexer circuit which then route neural stimulation signals from the neural stimulator to an electrode array which is connected to the outputs of the 1:2.sup.N demultiplexer. The demultiplexer circuit allows the number of individual electrodes in the electrode array to be increased by a factor of 2.sup.N with N generally being in a range of 2-4.

  7. Growth hormone stimulation test (image)

    Science.gov (United States)

    ... stimulation test is usually performed to identify if hGH (human growth hormone) is deficient. The test is ... amino acid arginine in a vein to raise hGH levels. The test measures the ability of the ...

  8. Optical antenna enhanced spontaneous emission.

    Science.gov (United States)

    Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C

    2015-02-10

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼ 200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ∼ 115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼ 2,500 × spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d(2). Unfortunately, at d antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.

  9. Economics of nuclear gas stimulation

    International Nuclear Information System (INIS)

    Frank, G.W.; Coffer, H.F.; Luetkehans, G.R.

    1970-01-01

    Nuclear stimulation of the Mesaverde Formation in the Piceance Basin appears to be the only available method that can release the contained gas economically. In the Rulison Field alone estimates show six to eight trillion cubic feet of gas may be made available by nuclear means, and possibly one hundred trillion cubic feet could be released in the Piceance Basin. Several problems remain to be solved before this tremendous gas reserve can be tapped. Among these are (1) rates of production following nuclear stimulation; (2) costs of nuclear stimulation; (3) radioactivity of the chimney gas; and (4) development of the ideal type of device to carry out the stimulations. Each of these problems is discussed in detail with possible solutions suggested. First and foremost is the rate at which gas can be delivered following nuclear stimulation. Calculations have been made for expected production behavior following a 5-kiloton device and a 40-kiloton device with different permeabilities. These are shown, along with conventional production history. The calculations show that rates of production will be sufficient if costs can be controlled. Costs of nuclear stimulation must be drastically reduced for a commercial process. Project Rulison will cost approximately $3.7 million, excluding lease costs, preliminary tests, and well costs. At such prices, nothing can possibly be commercial; however, these costs can come down in a logical step-wise fashion. Radiation contamination of the gas remains a problem. Three possible solutions to this problem are included. (author)

  10. Superresolution Imaging of Optical Vortices in a Speckle Pattern

    Science.gov (United States)

    Pascucci, Marco; Tessier, Gilles; Emiliani, Valentina; Guillon, Marc

    2016-03-01

    We characterize, experimentally, the intensity minima of a polarized high numerical aperture optical speckle pattern and the topological charges of the associated optical vortices. The negative of a speckle pattern is imprinted in a uniform fluorescent sample by photobleaching. The remaining fluorescence is imaged with superresolution stimulated emission depletion microscopy, which reveals subdiffraction fluorescence confinement at the center of optical vortices. The intensity statistics of saturated negative speckle patterns are predicted and measured. The charge of optical vortices is determined by controlling the handedness of circular polarization, and the creation or annihilation of a vortex pair along propagation is shown.

  11. Quantum Optics

    CERN Document Server

    Garrison, J C

    2008-01-01

    Quantum optics, i.e. the interaction of individual photons with matter, began with the discoveries of Planck and Einstein, but in recent years it has expanded beyond pure physics to become an important driving force for technological innovation. This book serves the broader readership growing out of this development by starting with an elementary description of the underlying physics and then building up a more advanced treatment. The reader is led from the quantum theory of thesimple harmonic oscillator to the application of entangled states to quantum information processing. An equally impor

  12. Deep Brain Stimulation for Parkinson's Disease

    Science.gov (United States)

    ... Home » Disorders » All Disorders Deep Brain Stimulation for Parkinson's Disease Information Page Deep Brain Stimulation for Parkinson's Disease Information Page What research is being done? The ...

  13. EDITORIAL: Optical orientation Optical orientation

    Science.gov (United States)

    SAME ADDRESS *, Yuri; Landwehr, Gottfried

    2008-11-01

    priority of the discovery in the literature, which was partly caused by the existence of the Iron Curtain. I had already enjoyed contact with Boris in the 1980s when the two volumes of Landau Level Spectroscopy were being prepared [2]. He was one of the pioneers of magneto-optics in semiconductors. In the 1950s the band structure of germanium and silicon was investigated by magneto-optical methods, mainly in the United States. No excitonic effects were observed and the band structure parameters were determined without taking account of excitons. However, working with cuprous oxide, which is a direct semiconductor with a relative large energy gap, Zakharchenya and his co-worker Seysan showed that in order to obtain correct band structure parameters, it is necessary to take excitons into account [3]. About 1970 Boris started work on optical orientation. Early work by Hanle in Germany in the 1920s on the depolarization of luminescence in mercury vapour by a transverse magnetic field was not appreciated for a long time. Only in the late 1940s did Kastler and co-workers in Paris begin a systematic study of optical pumping, which led to the award of a Nobel prize. The ideas of optical pumping were first applied by Georges Lampel to solid state physics in 1968. He demonstrated optical orientation of free carriers in silicon. The detection method was nuclear magnetic resonance; optically oriented free electrons dynamically polarized the 29Si nuclei of the host lattice. The first optical detection of spin orientation was demonstrated by with the III-V semiconductor GaSb by Parsons. Due to the various interaction mechanisms of spins with their environment, the effects occurring in semiconductors are naturally more complex than those in atoms. Optical detection is now the preferred method to detect spin alignment in semiconductors. The orientation of spins in crystals pumped with circularly polarized light is deduced from the degree of circular polarization of the recombination

  14. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  15. Combining infrared- and green-laser stimulation sources in single-grain luminescence measurements of feldspar and quartz

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.; Murray, A.S.

    2003-01-01

    possible to interchangeably use the two laser sources for optical stimulation. This is especially valuable for the measurement of feldspars. The power density using the IR laser at the grain is similar to500 W cm(-2), and stimulation for 1 s reduces the OSL signal to near background level. Initial results...... on grains from two feldspar samples are described. These show that the ratio of the OSL signal under green and IR stimulation is similar for all the feldspar grains. As expected, the ratio for quartz grains is very different, with a much weaker signal when using IR stimulation. For the two feldspars...

  16. Ovarian stimulation, endometrium and implantation

    Directory of Open Access Journals (Sweden)

    mandana Beigi Boroujeni

    2011-03-01

    Full Text Available In the Paper article, the collection of the studies related to the effect of ovarian stimulation on endometrium of uterus and implantation have been investigated. History: Monash group used ovarian stimulation method for the first time in infertility treatment and also, they could increase the pregnancy rate using this method. However, the percentage of successful embryonic implantation has been decreased by this method due to imbalance of hormones and the effect of these hormonal changes on endometrium. Materials and Methods: Studies done by researchers have shown that ovarian stimulation causes undesirable changes in endometrium which in turn such alterations lead to inadequate attachment of embryo to endometrium and finally decrease the percentage of embryonic implantation. Conclusion: Based on several researches and the importance of using the ovarian stimulation method in treatment of infertility, also due to undesirable effects that ovarian stimulation has on endometrium during embryonic implantation it is inevitable that more investigations should be done for improvement of treatment methods in infertility clinics.

  17. Evoked Electromyographically Controlled Electrical Stimulation

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Hayashibe

    2016-07-01

    Full Text Available Time-variant muscle responses under electrical stimulation (ES are often problematic for all the applications of neuroprosthetic muscle control. This situation limits the range of ES usage in relevant areas, mainly due to muscle fatigue and also to changes in stimulation electrode contact conditions, especially in transcutaneous ES. Surface electrodes are still the most widely used in noninvasive applications.Electrical field variations caused by changes in the stimulation contact condition markedly affect the resulting total muscle activation levels. Fatigue phenomena under functional electrical stimulation (FES are also well known source of time-varying characteristics coming from muscle response under ES. Therefore it is essential to monitor the actual muscle state and assess the expected muscle response by ES so as to improve the current ES system in favour of adaptive muscle-response-aware FES control. To deal with this issue, we have been studying a novel control technique using evoked electromyography (eEMG signals to compensate for these muscle time-variances under ES for stable neuroprosthetic muscle control. In this perspective article, I overview the background of this topic and highlight important points to be aware of when using ES to induce the desired muscle activation regardless of the time-variance. I also demonstrate how to deal with the common critical problem of ES to move toward robust neuroprosthetic muscle control with the Evoked Electromyographically Controlled Electrical Stimulation paradigm.

  18. Metrology of reflection optics for synchrotron radiation

    International Nuclear Information System (INIS)

    Takacs, P.Z.

    1985-09-01

    Recent years have seen an almost explosive growth in the number of beam lines on new and existing synchrotron radiation facilities throughout the world. The need for optical components to utilize the unique characteristics of synchrotron radiation has increased accordingly. Unfortunately, the technology to manufacture and measure the large, smooth, exotic optical surfaces required to focus and steer the synchrotron radiation beam has not progressed as rapidly as the operational demands on these components. Most companies do not wish to become involved with a project that requires producing a single, very expensive, aspheric optic with surface roughness and figure tolerances that are beyond their capabilities to measure. This paper will review some of the experiences of the National Synchrotron Light Source in procuring grazing incidence optical components over the past several years. We will review the specification process - how it is related to the function of the optic, and how it relates to the metrology available during the manufacturing process and after delivery to the user's laboratory. We will also discuss practical aspects of our experience with new technologies, such as single point diamond turning of metal mirrors and the use of SiC as a mirror material. Recent advances in metrology instrumentation have the potential to move the measurement of surface figure and finish from the research laboratory into the optical shop, which should stimulate growth and interest in the manufacturing of optics to meet the needs of the synchrotron radiation user community

  19. Violet stimulated luminescence: geo- or thermochronometer?

    International Nuclear Information System (INIS)

    Ankjærgaard, C.; Guralnik, B.; Porat, N.; Heimann, A.; Jain, M.; Wallinga, J.

    2015-01-01

    The method of quartz optically stimulated luminescence (OSL) dating is widely used, but generally limited to the past ∼0.1 million years (Ma) due to early saturation of the desired signal. Violet stimulated luminescence (VSL) of quartz has previously been shown as a promising alternative, with a dose saturation level ∼20 times higher compared to that of OSL, excellent thermal stability on the 10 11 year time scale, and agreement between VSL and OSL ages up to ∼0.3 Ma. Here we explore the usability of the VSL signal to date older quartz samples from palaeosols, whose ages are bracketed by K–Ar ages and palaeomagnetic data of the interbedded basalts, emplaced between 1.6 and 0.7 Ma. VSL ages from three palaeosols largely underestimate the independent ages of their overlying basalts. This can be explained either by a low-temperature thermal anomaly resetting the VSL signal in nature, and/or by an insufficient measurement protocol, unable to correctly translate the natural signal into the equivalent laboratory dose. - Highlights: • We investigate the potential of VSL to date quartz from early Quaternary palaeosols (1.6 - 0.7 Ma old). • The VSL signals show good reproducibility, dose response, thermal stability, and dose recovery. • VSL ages from three palaeosols underestimate the independent K-Ar ages by 50% or more. • It is possible that the VSL ages are correct, but have been reset by thermal anomalies. • Further investigation of the natural VSL signal is needed to confirm these underestimating ages.

  20. The Electrical Stimulation Modifies the Cerebral Function

    Science.gov (United States)

    Rocha, Luisa Lilia; López-Meraz, María Leonor; Cuéllar-Herrera, Manola; Neri-Bazán., Leticia

    2002-08-01

    Electrical stimulation has been used for therapeuthic purposes. In this review, we present the clinical and scientific bases for using electrical stimulation as a treatment for pharmacological refractory epilepsy. We also describe results in receptors of inhibitory neurotransmitters obtained in rat brain with or without epilepsy, undergoing brain stimulation. Brain electrical stimulation may improve our understanding of brain function and neuroplasticity.

  1. Mechanisms of deep brain stimulation

    Science.gov (United States)

    Cheng, Jennifer J.; Eskandar, Emad N.

    2015-01-01

    Deep brain stimulation (DBS) is widely used for the treatment of movement disorders including Parkinson's disease, essential tremor, and dystonia and, to a lesser extent, certain treatment-resistant neuropsychiatric disorders including obsessive-compulsive disorder. Rather than a single unifying mechanism, DBS likely acts via several, nonexclusive mechanisms including local and network-wide electrical and neurochemical effects of stimulation, modulation of oscillatory activity, synaptic plasticity, and, potentially, neuroprotection and neurogenesis. These different mechanisms vary in importance depending on the condition being treated and the target being stimulated. Here we review each of these in turn and illustrate how an understanding of these mechanisms is inspiring next-generation approaches to DBS. PMID:26510756

  2. Quantum optics for experimentalists

    CERN Document Server

    Ou, Zhe-Yu Jeff

    2017-01-01

    This book on quantum optics is from the point of view of an experimentalist. It approaches the theory of quantum optics with the language of optical modes of classical wave theory, with which experimentalists are most familiar.

  3. Introduction to biomedical optics

    CERN Document Server

    Splinter, Robert

    2006-01-01

    GENERAL BIOMEDICAL OPTICS THEORYIntroduction to the Use of Light for Diagnostic and Therapeutic ModalitiesWhat Is Biomedical Optics?Biomedical Optics TimelineElementary Optical DiscoveriesHistorical Events in Therapeutic and Diagnostic Use of LightLight SourcesCurrent State of the ArtSummaryAdditional ReadingProblemsReview of Optical Principles: Fundamental Electromagnetic Theory and Description of Light SourcesDefinitions in OpticsKirchhoff's Laws of RadiationElectromagnetic Wave TheoryLight SourcesApplications of Various LasersSummaryAdditional ReadingProblemsReview of Optical Principles: Classical OpticsGeometrical OpticsOther Optical PrinciplesQuantum PhysicsGaussian OpticsSummaryAdditional ReadingProblemsReview of Optical Interaction PropertiesAbsorption and ScatteringSummaryAdditional ReadingProblemsLight-Tissue Interaction VariablesLaser VariablesTissue VariablesLight Transportation TheoryLight Propagation under Dominant AbsorptionSummaryNomenclatureAdditional ReadingProblemsLight-Tissue Interaction Th...

  4. Coding for optical channels

    CERN Document Server

    Djordjevic, Ivan; Vasic, Bane

    2010-01-01

    This unique book provides a coherent and comprehensive introduction to the fundamentals of optical communications, signal processing and coding for optical channels. It is the first to integrate the fundamentals of coding theory and optical communication.

  5. Comparison of mild stimulation and conventional stimulation in ART outcome.

    Science.gov (United States)

    Karimzadeh, Mohammad Ali; Ahmadi, Shahnaz; Oskouian, Homa; Rahmani, Elham

    2010-04-01

    To provide a treatment for particular condition that is the most effective treatment with the least risk and cost for the patient we compared the efficacy of using clomiphene 100 mg + delayed low dose gonadotropin + flexible GnRH antagonist administration for ovarian stimulation protocol and GnRH agonist + gonadotropin for stimulation protocol in IVF outcome. Clinical outcome of 243 women with regularly menstruation who were candidate for IVF. They had undergone stimulation with GnRH agonist and gonadotropin (group A) or clomiphene citrate, gonadotropin and GnRH antagonist (group B). Main outcome was ongoing pregnancy. There were no significant difference in mean age, cause of infertility, basal FSH, BMI, duration of infertility, endometrial thickness on the day HCG administration in two groups. The number of recovered oocytes, obtained embryos, transferred embryos, peak of estradiol on the day HCG administration and OHSS were significantly higher in group A. Significantly more patients in control group had embryos for cryopreservation. There were no significant difference in clinical pregnancy rate and ongoing pregnancy rate between two groups. Clomiphene + delayed low dose gonadotropin + flexible GnRH - antagonist stimulation is an acceptable alternative protocol for IVF in patients with regularly menstruation.

  6. Enteral feeding without pancreatic stimulation

    DEFF Research Database (Denmark)

    Kaushik, Neeraj; Pietraszewski, Marie; Holst, Jens Juul

    2005-01-01

    OBJECTIVE: All forms of commonly practiced enteral feeding techniques stimulate pancreatic secretion, and only intravenous feeding avoids it. In this study, we explored the possibility of more distal enteral infusions of tube feeds to see whether activation of the ileal brake mechanism can result...... in plasma glucagon-like peptide-1 and peptide YY concentrations. CONCLUSIONS: Our results suggest that enteral feeding can be given without stimulating pancreatic trypsin secretion provided it is delivered into the mid-distal jejunum. The mechanism may involve activation of the ileal brake mechanism....

  7. Thermally stimulated properties of amber

    International Nuclear Information System (INIS)

    Bowlt, C.

    1983-01-01

    Thermoelectrets yielded thermally stimulated currents but radioelectrets could not be produced even following exposures of 16000 R of ionising radiation. It is concluded that the thermally stimulated currents are due to the depolarisation of dipoles, with activation energy of 1.4 +- 0.1 eV, rather than to discharge of trapped charge carriers. Amber exhibits thermal luminescence following exposure to light of lambda < 500 nm but not to ionising radiation after exposures up to 5500 R, indicating localised impurity/trap/recombination complexes in the specimen surface, with a trap depth of 1.5 +- 0.1 eV. (author)

  8. Photovoltaic Pixels for Neural Stimulation: Circuit Models and Performance.

    Science.gov (United States)

    Boinagrov, David; Lei, Xin; Goetz, Georges; Kamins, Theodore I; Mathieson, Keith; Galambos, Ludwig; Harris, James S; Palanker, Daniel

    2016-02-01

    Photovoltaic conversion of pulsed light into pulsed electric current enables optically-activated neural stimulation with miniature wireless implants. In photovoltaic retinal prostheses, patterns of near-infrared light projected from video goggles onto subretinal arrays of photovoltaic pixels are converted into patterns of current to stimulate the inner retinal neurons. We describe a model of these devices and evaluate the performance of photovoltaic circuits, including the electrode-electrolyte interface. Characteristics of the electrodes measured in saline with various voltages, pulse durations, and polarities were modeled as voltage-dependent capacitances and Faradaic resistances. The resulting mathematical model of the circuit yielded dynamics of the electric current generated by the photovoltaic pixels illuminated by pulsed light. Voltages measured in saline with a pipette electrode above the pixel closely matched results of the model. Using the circuit model, our pixel design was optimized for maximum charge injection under various lighting conditions and for different stimulation thresholds. To speed discharge of the electrodes between the pulses of light, a shunt resistor was introduced and optimized for high frequency stimulation.

  9. Tunable laser optics

    CERN Document Server

    Duarte, FJ

    2015-01-01

    This Second Edition of a bestselling book describes the optics and optical principles needed to build lasers. It also highlights the optics instrumentation necessary to characterize laser emissions and focuses on laser-based optical instrumentation. The book emphasizes practical and utilitarian aspects of relevant optics including the essential theory. This revised, expanded, and improved edition contains new material on tunable lasers and discusses relevant topics in quantum optics.

  10. Optical Chirality in Nonlinear Optics: Application to High Harmonic Generation

    Science.gov (United States)

    Neufeld, Ofer; Cohen, Oren

    2018-03-01

    Optical chirality (OC)—one of the fundamental quantities of electromagnetic fields—corresponds to the instantaneous chirality of light. It has been utilized for exploring chiral light-matter interactions in linear optics, but has not yet been applied to nonlinear processes. Motivated to explore the role of OC in the generation of helically polarized high-order harmonics and attosecond pulses, we first separate the OC of transversal and paraxial beams to polarization and orbital terms. We find that the polarization-associated OC of attosecond pulses corresponds approximately to that of the pump in the quasimonochromatic case, but not in the multichromatic pump cases. We associate this discrepancy with the fact that the polarization OC of multichromatic pumps vary rapidly in time along the optical cycle. Thus, we propose new quantities, noninstantaneous polarization-associated OC, and time-scale-weighted polarization-associated OC, and show that these quantities link the chirality of multichromatic pumps and their generated attosecond pulses. The presented extension to OC theory should be useful for exploring various nonlinear chiral light-matter interactions. For example, it stimulates us to propose a tricircular pump for generation of highly elliptical attosecond pulses with a tunable ellipticity.

  11. Noninvasive Transcranial Brain Stimulation and Pain

    OpenAIRE

    Rosen, Allyson C.; Ramkumar, Mukund; Nguyen, Tam; Hoeft, Fumiko

    2009-01-01

    Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are two noninvasive brain stimulation techniques that can modulate activity in specific regions of the cortex. At this point, their use in brain stimulation is primarily investigational; however, there is clear evidence that these tools can reduce pain and modify neurophysiologic correlates of the pain experience. TMS has also been used to predict response to surgically implanted stimulation for the tre...

  12. Upconversion lasing, heat transfer and stimulated cooling in solids

    Science.gov (United States)

    Sandner, K.; Ritsch, H.

    2014-02-01

    A laser can convert pump energy to light in a coherent single mode field of an optical resonator. If the energy is taken from a thermodynamic reservoir the energy conversion process reaches Carnot efficiency. From a different viewpoint, a laser thus can also be seen as a refrigerator for efficient heat extraction from hot environment via stimulated emission. This process can be studied well at a toy model of a quantum well structure with suitably designed tunnel-coupled wells kept at different temperature. Lasing appears concurrent with amplified heat flow and points to a new form of stimulated solid state cooling. From a practical point of view, this mechanism could help to raise the operating temperature limit of quantum cascade lasers by substituting phonon emission driven injection, which generates intrinsic heat, by an extended model with phonon absorption steps. Other implementations in systems with phonon driven up conversion of photons could be equally envisaged.

  13. Two-tone frequency-modulation stimulated Rayleigh spectroscopy.

    Science.gov (United States)

    Faris, Gregory W; Markosyan, Ashot; Porter, Christina L; Doshay, Sage

    2014-08-01

    We have demonstrated two-tone frequency-modulation (FM) stimulated Rayleigh spectroscopy. This method can provide high spectral resolution (∼1  MHz), excellent pump/probe detuning accuracy, and near-shot-noise-limited signal-to-noise ratios using a single narrowband laser as the master oscillator. Pump/probe detuning and FM sideband generation are produced with an electro-optic modulator. A double-pass two-rod Nd:YAG amplifier provides peak powers near 1 kW for the pump beam. Unlike with two-tone FM absorption spectroscopy, the phase signal is retained for two-tone FM Rayleigh spectroscopy. Measurements confirm that the shape of the phase component of the stimulated thermal Rayleigh peak agrees with theory.

  14. Brillouin suppression in a fiber optical parametric amplifier by combining temperature distribution and phase modulation

    DEFF Research Database (Denmark)

    Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel

    2008-01-01

    We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation.......We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation....

  15. Analytical study of nonlinear phase shift through stimulated Brillouin scattering in single mode fiber with the pump power recycling technique

    International Nuclear Information System (INIS)

    Al-Asadi, H A; Mahdi, M A; Bakar, A A A; Adikan, F R Mahamd

    2011-01-01

    We present a theoretical study of nonlinear phase shift through stimulated Brillouin scattering in single mode optical fiber. Analytical expressions describing the nonlinear phase shift for the pump and Stokes waves in the pump power recycling technique have been derived. The dependence of the nonlinear phase shift on the optical fiber length, the reflectivity of the optical mirror and the frequency detuning coefficient have been analyzed for different input pump power values. We found that with the recycling pump technique, the nonlinear phase shift due to stimulated Brillouin scattering reduced to less than 0.1 rad for 5 km optical fiber length and 0.65 reflectivity of the optical mirror, respectively, at an input pump power equal to 30 mW

  16. Optical Remote Sensing Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Optical Remote Sensing Laboratory deploys rugged, cutting-edge electro-optical instrumentation for the collection of various event signatures, with expertise in...

  17. Intelligent Optics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Intelligent Optics Laboratory supports sophisticated investigations on adaptive and nonlinear optics; advancedimaging and image processing; ground-to-ground and...

  18. Fibre-optic communications

    CERN Document Server

    Lecoy, Pierre

    2010-01-01

    This book describes in a comprehensive manner the components and systems of fiber optic communications and networks. The first section explains the theory of multimode and single-mode fibers, then the technological features, including manufacturing, cabling, and connecting. The second section describes the various components (passive and active optical components, integrated optics, opto-electronic transmitters and receivers, and optical amplifiers) used in fiber optic systems. Finally, the optical transmission system design is explained, and applications to optical networks and fiber optic se

  19. Optical-Thermal Response of Laser-Irradiated Tissue

    CERN Document Server

    Welch, Ashley J

    2011-01-01

    The second edition of 'Optical-Thermal Response of Laser-Irradiated Tissue' maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes: 1. light propagation and diagnostic appl...

  20. GABAA receptor-mediated modulation of neuronal activity propagation upon tetanic stimulation in rat hippocampal slices.

    Science.gov (United States)

    Tominaga, Takashi; Tominaga, Yoko

    2010-10-01

    Tetanic stimulation (100 Hz), which can induce long-term potentiation in synaptic connections in the hippocampal CA1 region, causes γ-aminobutyric acid (GABA)(A) receptor-mediated long-lasting depolarization of postsynaptic neurons. However, it is not clear how this stimulation modulates neuronal activity propagation. We studied tetanic burst-induced neuronal responses in the hippocampal CA1 region by using optical-recording methods employing a voltage-sensitive dye and focused on GABA(A) receptor-mediated modulation. We observed that burst stimulation induced long-lasting depolarization and progressive decrease in individual excitatory postsynaptic potentials (EPSPs). Both these effects were suppressed by picrotoxin, a GABA(A) receptor antagonist. Under whole-cell voltage-clamp conditions, we observed a long-lasting inhibitory current (IPSC) and a prominent progressive decrease in the amplitude of the excitatory postsynaptic current (EPSC). Further, picrotoxin inhibited the IPSC and the progressive decrease in EPSC. The optically recorded long-lasting depolarization and progressive decrease of EPSPs were strongly dependent on the distance between the recording electrode and the stimulation site. Optical recordings performed across a wide swatch of CA1 revealed that the decrease in activity propagation was followed by facilitation of propagation after recovery and that this facilitation also depended on GABA(A) receptors. Intense activation of GABA(A) receptors is a key factor shaping the spatiotemporal patterns of high-frequency stimulation-induced responses in the CA1 region.

  1. Stimulated emission depletion (STED) nanoscopy of a fluorescent protein-labeled organelle inside a living cell

    OpenAIRE

    Hein, Birka; Willig, Katrin I.; Hell, Stefan W.

    2008-01-01

    We demonstrate far-field optical imaging with subdiffraction resolution of the endoplasmic reticulum (ER) in the interior of a living mammalian cell. The diffraction barrier is overcome by applying stimulated emission depletion (STED) on a yellow fluorescent protein tag. Imaging individual structural elements of the ER revealed a focal plane (x, y) resolution of

  2. Red-IR stimulated luminescence in K-feldspar: Single or multiple trap origin?

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Jain, Mayank; Tidemand-Lichtenberg, Peter

    2012-01-01

    We investigate on the origins of the infra-red stimulated luminescence (IRSL) signals in 3 potassium feldspars based on IR-red spectroscopy (700–1050 nm) using a fiber-coupled tunable Ti:Sapphire laser, in combination with different thermal and optical (pre)treatments of the samples. We also...

  3. Quantum-dot nano-cavity lasers with Purcell-enhanced stimulated emission

    DEFF Research Database (Denmark)

    Gregersen, Niels; Skovgård, Troels Suhr; Lorke, Michael

    2012-01-01

    We present a rate equation model for quantum-dot light-emitting devices that take into account Purcell enhancement of both spontaneous emission and stimulated emission as well as the spectral profile of the optical and electronic density-of-states. We find that below threshold the b-factor in a q...

  4. Influence of stimulated Raman scattering on the conversion efficiency in four wave mixing

    International Nuclear Information System (INIS)

    Wunderlich, R.; Moore, M.A.; Garrett, W.R.; Payne, M.G.

    1988-01-01

    Secondary nonlinear optical effects following parametric four wave mixing in sodium vapor are investigated. The generated ultraviolet radiation induces stimulated Raman scattering and other four wave mixing process. Population transfer due to Raman transitions strongly influences the phase matching conditions for the primary mixing process. Pulse shortening and a reduction in conversion efficiency are observed. 8 refs., 3 figs

  5. Towards dating Quaternary sediments using the quartz Violet Stimulated Luminescence (VSL) signal

    NARCIS (Netherlands)

    Ankjaergaard, C.; Jain, M.; Wallinga, J.

    2013-01-01

    Quartz optically stimulated luminescence (OSL) dating is widely used to determine the time of deposition and burial of Late Quaternary sediments. Application of the method is usually limited to the past 150,000 years due to early saturation of the OSL signal. Here we explore the potential to date

  6. System-bath correlation function probed by conventional and time-gated stimulated photon echo

    NARCIS (Netherlands)

    Boeij, Wim P. de; Pshenichnikov, Maxim S.; Wiersma, Douwe A.

    1996-01-01

    We show how in the framework of the multimode Brownian oscillator model the system-bath correlation function can be derived from conventional and time-gated stimulated photon echo experiments and consideration of the linear optical spectra. Experiments are performed on the infrared dye DTTCI in room

  7. Optimizing performance by stimulating conflict

    NARCIS (Netherlands)

    van de Vliert, E.; de Dreu, C.K.W.

    1994-01-01

    To enhance the quality of group decision making, to promote affective acceptance of decisions by all participants involved, or to increase joint outcomes, a principal party or a third party may stimulate social conflict. We argue that when conflict focuses on identity issues, when tension level is

  8. Stimulated emission during axial channeling

    International Nuclear Information System (INIS)

    Ternov, I.M.; Khalilov, V.R.; Kholomai, B.V.

    1985-01-01

    A quantum-mechanical analysis shows that it would be possible to achieve stimulated emission in an axisymmetric focusing electric field by a mechanism based on the nonuniform spacing of levels in the electron energy spectrum and on recoil effects during the emission and absorption of photons by the electrons

  9. Optimizing performance by conflict stimulation

    NARCIS (Netherlands)

    Van de Vliert, E; De Dreu, C K W

    To enhance the quality of group decision making, to promote affective acceptance of decisions by all participants involved, or to increase joint outcomes, a principal party or a third party may stimulate social conflict. We argue that when conflict focuses on identity issues, when tension level is

  10. Transcranial magnetic stimulation in schizophrenia.

    Science.gov (United States)

    Zaman, Rashid; Thind, Dilraj; Kocmur, Marga

    2008-11-01

    Transcranial magnetic stimulation (TMS) is a non-invasive and painless way of stimulating the neural tissue (cerebral cortex, spinal roots, and cranial and peripheral nerves). The first attempts at stimulating the neural tissue date back to 1896 by d'Arsonval; however, it was successfully carried out by Barker and colleagues in Sheffield, UK, in 1985. It soon became a useful tool in neuroscience for neurophysiologists and neurologists and psychiatrists. The original single-pulse TMS, largely used as an investigative tool, was further refined and developed in the early 1990s into what is known as repetitive TMS (rTMS), having a frequency range of 1-60 Hz. The stimulation by both TMS and rTMS of various cortical regions displayed alteration of movement, mood, and behavior, leading researchers to investigate a number of psychiatric and neuropsychiatric disorders, as well as to explore its therapeutic potential. There is now a large amount of literature on the use of TMS/rTMS in depression; however, its use in schizophrenia, both as an investigative and certainly as a therapeutic tool is relatively recent with a limited but increasing number of publications. In this article, we will outline the principles of TMS/rTMS and critically review their use in schizophrenia both as investigative and potential therapeutic tools.

  11. Thermally stimulated luminescence and photoluminescence ...

    Indian Academy of Sciences (India)

    2012-01-13

    Jan 13, 2012 ... Peltier cooled photo-multiplier tube as detector (Jain et al. 2008). The acquisition and analysis of the data were carried out by F-900 software supplied by Edinburgh Analytical. Instruments, UK. Thermally stimulated luminescence (TSL) glow curves were recorded using home-built unit between. 300 and ...

  12. Ovarian stimulation and embryo quality

    NARCIS (Netherlands)

    Baart, Esther; Macklon, Nick S.; Fauser, Bart J. C. M.

    To Study the effects of different ovarian stimulation approaches on oocyte and embryo quality, it is imperative to assess embryo quality with a reliable and objective method. Embryos rated as high quality by standardized morphological assessment are associated with higher implantation and pregnancy

  13. Breast Cancer Stimulation of Osteolysis

    Science.gov (United States)

    2000-09-01

    number seen in osteoporosis . M- increase osteoclast activity. Paracrine stimulation of osteo-clas aciviy my bea pi ay mchansm y wich CSF also promotes the...effects on gies, including periodontitis and orthopedic implant loos- kidney and bone metabolism. Paracrine actions of ening. Antibody blockade of

  14. Orientation selective deep brain stimulation

    Science.gov (United States)

    Lehto, Lauri J.; Slopsema, Julia P.; Johnson, Matthew D.; Shatillo, Artem; Teplitzky, Benjamin A.; Utecht, Lynn; Adriany, Gregor; Mangia, Silvia; Sierra, Alejandra; Low, Walter C.; Gröhn, Olli; Michaeli, Shalom

    2017-02-01

    Objective. Target selectivity of deep brain stimulation (DBS) therapy is critical, as the precise locus and pattern of the stimulation dictates the degree to which desired treatment responses are achieved and adverse side effects are avoided. There is a clear clinical need to improve DBS technology beyond currently available stimulation steering and shaping approaches. We introduce orientation selective neural stimulation as a concept to increase the specificity of target selection in DBS. Approach. This concept, which involves orienting the electric field along an axonal pathway, was tested in the corpus callosum of the rat brain by freely controlling the direction of the electric field on a plane using a three-electrode bundle, and monitoring the response of the neurons using functional magnetic resonance imaging (fMRI). Computational models were developed to further analyze axonal excitability for varied electric field orientation. Main results. Our results demonstrated that the strongest fMRI response was observed when the electric field was oriented parallel to the axons, while almost no response was detected with the perpendicular orientation of the electric field relative to the primary fiber tract. These results were confirmed by computational models of the experimental paradigm quantifying the activation of radially distributed axons while varying the primary direction of the electric field. Significance. The described strategies identify a new course for selective neuromodulation paradigms in DBS based on axonal fiber orientation.

  15. Photoluminescence, thermally stimulated luminescence and ...

    Indian Academy of Sciences (India)

    an important role in the development of thermolumine- scent dosimeters (Vohra et al 1980; Shinde et al 1996) and offer a very fertile area for further studies to eluci- date the thermally stimulated reactions resulting in lumine- scence. Actinide doped alkaline-earth sulphates are of spe- cial interest due to an array of defect ...

  16. Thalamic stimulation in absence epilepsy

    NARCIS (Netherlands)

    Luttjohann, A.K.; Luijtelaar, E.L.J.M. van

    2013-01-01

    Purpose The site specific effects of two different types of electrical stimulation of the thalamus on electroencephalic epileptic activity as generated in the cortico-thalamo-cortical system were investigated in genetic epileptic WAG/Rij rats, a well characterized and validated absence

  17. Underwater optical wireless communication network

    Science.gov (United States)

    Arnon, Shlomi

    2010-01-01

    The growing need for underwater observation and subsea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, biogeochemical, evolutionary, and ecological changes in the sea, ocean, and lake environments, and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. Models are presented for three kinds of optical wireless communication links: (a) a line-of-sight link, (b) a modulating retroreflector link, and (c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered light it was possible to mitigate this decrease in some cases. It is concluded from the analysis that a high-data-rate underwater optical wireless network is a feasible solution for emerging applications such as UUV-to-UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  18. Light Optics for Optical Stochastic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Andorf, Matthew [NICADD, DeKalb; Lebedev, Valeri [Fermilab; Piot, Philippe [NICADD, DeKalb; Ruan, Jinhao [Fermilab

    2016-06-01

    In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.

  19. Stimulation of phagocytosis by sulforaphane

    Energy Technology Data Exchange (ETDEWEB)

    Suganuma, Hiroyuki, E-mail: hsuganu1@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Fahey, Jed W., E-mail: jfahey@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Bryan, Kelley E., E-mail: kbryanm1@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Healy, Zachary R., E-mail: zhealy1@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Talalay, Paul, E-mail: ptalalay@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States)

    2011-02-04

    Research highlights: {yields} Sulforaphane stimulates the phagocytosis of RAW 264.7 macrophages under conditions of serum deprivation. {yields} This effect does not require Nrf2-dependent induction of phase 2 genes. {yields} Inactivation of macrophage migration inhibitory factor (MIF) by sulforaphane may be involved in stimulation of phagocytosis by sulforaphane. -- Abstract: Sulforaphane, a major isothiocyanate derived from cruciferous vegetables, protects living systems against electrophile toxicity, oxidative stress, inflammation, and radiation. A major protective mechanism is the induction of a network of endogenous cytoprotective (phase 2) genes that are regulated by transcription factor Nrf2. To obtain a more detailed understanding of the anti-inflammatory and immunomodulatory effects of sulforaphane, we evaluated its effect on the phagocytosis activity of RAW 264.7 murine macrophage-like cells by measuring the uptake of 2-{mu}m diameter polystyrene beads. Sulforaphane raised the phagocytosis activity of RAW 264.7 cells but only in the absence or presence of low concentrations (1%) of fetal bovine serum. Higher serum concentrations depressed phagocytosis and abolished its stimulation by sulforaphane. This stimulation did not depend on the induction of Nrf2-regulated genes since it occurred in peritoneal macrophages of nrf2{sup -/-} mice. Moreover, a potent triterpenoid inducer of Nrf2-dependent genes did not stimulate phagocytosis, whereas sulforaphane and another isothiocyanate (benzyl isothiocyanate) had comparable inducer potencies. It has been shown recently that sulforaphane is a potent and direct inactivator of macrophage migration inhibitory factor (MIF), an inflammatory cytokine. Moreover, the addition of recombinant MIF to RAW 264.7 cells attenuated phagocytosis, but sulforaphane-inactivated MIF did not affect phagocytosis. The inactivation of MIF may therefore be involved in the phagocytosis-enhancing activity of sulforaphane.

  20. Early-light embryonic stimulation suggests a second route, via gene activation, to cerebral lateralization in vertebrates.

    Science.gov (United States)

    Chiandetti, Cinzia; Galliussi, Jessica; Andrew, Richard J; Vallortigara, Giorgio

    2013-01-01

    Genetic factors determine the asymmetrical position of vertebrate embryos allowing asymmetric environmental stimulation to shape cerebral lateralization. In birds, late-light stimulation, just before hatching, on the right optic nerve triggers anatomical and functional cerebral asymmetries. However, some brain asymmetries develop in absence of embryonic light stimulation. Furthermore, early-light action affects lateralization in the transparent zebrafish embryos before their visual system is functional. Here we investigated whether another pathway intervenes in establishing brain specialization. We exposed chicks' embryos to light before their visual system was formed. We observed that such early stimulation modulates cerebral lateralization in a comparable vein of late-light stimulation on active retinal cells. Our results show that, in a higher vertebrate brain, a second route, likely affecting the genetic expression of photosensitive regions, acts before the development of a functional visual system. More than one sensitive period seems thus available to light stimulation to trigger brain lateralization.

  1. Optical fiber applied to radiation detection

    International Nuclear Information System (INIS)

    Junior, Francisco A.B.; Costa, Antonella L.; Oliveira, Arno H. de; Vasconcelos, Danilo C.

    2015-01-01

    In the last years, the production of optical fibers cables has make possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to light signal transmission from a NaI(Tl) radiation detector is presented. The innovative device takes advantage mainly of the optical fibers small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches. (author)

  2. Optic Nerve Pit

    Science.gov (United States)

    ... Conditions Frequently Asked Questions Español Condiciones Chinese Conditions Optic Nerve Pit What is optic nerve pit? An optic nerve pit is a ... may be seen in both eyes. How is optic pit diagnosed? If the pit is not affecting ...

  3. Optical image encryption topology.

    Science.gov (United States)

    Yong-Liang, Xiao; Xin, Zhou; Qiong-Hua, Wang; Sheng, Yuan; Yao-Yao, Chen

    2009-10-15

    Optical image encryption topology is proposed based on the principle of random-phase encoding. Various encryption topological units, involving peer-to-peer, ring, star, and tree topologies, can be realized by an optical 6f system. These topological units can be interconnected to constitute an optical image encryption network. The encryption and decryption can be performed in both digital and optical methods.

  4. Stimulating the Comfort of Textile Electrodes in Wearable Neuromuscular Electrical Stimulation

    OpenAIRE

    Hui Zhou; Yi Lu; Wanzhen Chen; Zhen Wu; Haiqing Zou; Ludovic Krundel; Guanglin Li

    2015-01-01

    Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and then its impedance spectroscopy, stimulation thresholds, and stimulation comfort were quantitatively assessed and compared with those of a wet textile electrode and a hydrogel ele...

  5. Optics for dummies

    CERN Document Server

    Duree, Galen C

    2011-01-01

    The easy way to shed light on Optics In general terms, optics is the science of light. More specifically, optics is a branch of physics that describes the behavior and properties of light?including visible, infrared, and ultraviolet?and the interaction of light with matter. Optics For Dummies gives you an approachable introduction to optical science, methods, and applications. You'll get plain-English explanations of the nature of light and optical effects; reflection, refraction, and diffraction; color dispersion; optical devices, industrial, medical, and military applicatio

  6. Adaptive optics in microscopy.

    Science.gov (United States)

    Booth, Martin J

    2007-12-15

    The imaging properties of optical microscopes are often compromised by aberrations that reduce image resolution and contrast. Adaptive optics technology has been employed in various systems to correct these aberrations and restore performance. This has required various departures from the traditional adaptive optics schemes that are used in astronomy. This review discusses the sources of aberrations, their effects and their correction with adaptive optics, particularly in confocal and two-photon microscopes. Different methods of wavefront sensing, indirect aberration measurement and aberration correction devices are discussed. Applications of adaptive optics in the related areas of optical data storage, optical tweezers and micro/nanofabrication are also reviewed.

  7. Fiber optic connector

    Science.gov (United States)

    Rajic, Slobodan; Muhs, Jeffrey D.

    1996-01-01

    A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled.

  8. Integrated optics technology study

    Science.gov (United States)

    Chen, B.

    1982-01-01

    The materials and processes available for the fabrication of single mode integrated electrooptical components are described. Issues included in the study are: (1) host material and orientation, (2) waveguide formation, (3) optical loss mechanisms, (4) wavelength selection, (5) polarization effects and control, (6) laser to integrated optics coupling,(7) fiber optic waveguides to integrated optics coupling, (8) souces, (9) detectors. The best materials, technology and processes for fabrication of integrated optical components for communications and fiber gyro applications are recommended.

  9. Measurement of optical glasses

    International Nuclear Information System (INIS)

    Nicolau-Rebigan, S.

    1978-11-01

    The possibilities of measurement of the optical glasses parameters needed in building optical devices especially in lasers devices are presented. In the first chapter the general features of the main optical glasses as well as the modalities of obtaining them are given. Chapter two defines the optical glass parameters, and the third chapter describes the measuring methods of the optical glass parameters. Finally, the conclusions which point out the utilization of this paper are presented. (author)

  10. Optical imaging and spectroscopy

    CERN Document Server

    Brady, David J

    2009-01-01

    An essential reference for optical sensor system design This is the first text to present an integrated view of the optical and mathematical analysis tools necessary to understand computational optical system design. It presents the foundations of computational optical sensor design with a focus entirely on digital imaging and spectroscopy. It systematically covers: Coded aperture and tomographic imaging Sampling and transformations in optical systems, including wavelets and generalized sampling techniques essential to digital system analysis Geometric, wave, and statis

  11. "Slinky" coils for neuromagnetic stimulation.

    Science.gov (United States)

    Zimmermann, K P; Simpson, R K

    1996-04-01

    Future advances in neuromagnetic stimulation depend significantly on the design of coils with improved focality. Although in the absence of internal current sources, no true focusing of magnetically induced currents is possible, improvements in the focality of current concentrations passing through an area of biologic tissue are achievable through variations of the shape, orientation and size of neuromagnetic stimulating coils. The "butterfly" and the "4-leaf" coils are two examples of planar designs which achieve improved focality through centralization of the maximum coil current and peripheral distribution of the return currents. We introduce the "slinky" coil design as a 3-dimensional generalization of the principle of peripheral distribution of return currents and demonstrate its advantages over planar designs.

  12. Vagal stimulation in heart failure.

    Science.gov (United States)

    De Ferrari, Gaetano M

    2014-04-01

    Heart failure (HF) is accompanied by an autonomic imbalance that is almost always characterized by both increased sympathetic activity and withdrawal of vagal activity. Experimentally, vagal stimulation has been shown to exert profound antiarrhythmic activity and to improve cardiac function and survival in HF models. A open-label pilot clinical study in 32 patients with chronic HF has shown safety and tolerability of chronic vagal stimulation associated with subjective (improved quality of life and 6-min walk test) and objective improvements (reduced left ventricular systolic volumes and improved left ventricular ejection fraction). Three larger clinical studies, including a phase III trial are currently ongoing and will evaluate the clinical role of this new approach.

  13. Stimulated Superconductivity at Strong Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ning; Dong, Xi; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC

    2011-08-12

    Stimulating a system with time dependent sources can enhance instabilities, thus increasing the critical temperature at which the system transitions to interesting low-temperature phases such as superconductivity or superfluidity. After reviewing this phenomenon in non-equilibrium BCS theory (and its marginal fermi liquid generalization) we analyze the effect in holographic superconductors. We exhibit a simple regime in which the transition temperature increases parametrically as we increase the frequency of the time-dependent source.

  14. Transcranial Magnetic Stimulation in Children

    OpenAIRE

    Garvey, Marjorie A.; Mall, Volker

    2008-01-01

    Developmental disabilities (e.g. attention deficit disorder; cerebral palsy) are frequently associated with deviations of the typical pattern of motor skill maturation. Neurophysiologic tools, such as transcranial magnetic stimulation (TMS), which probe motor cortex function, can potentially provide insights into both typical neuromotor maturation and the mechanisms underlying the motor skill deficits in children with developmental disabilities. These insights may set the stage for finding ef...

  15. Deep brain stimulation in psychiatry.

    Science.gov (United States)

    Mohr, Pavel

    2008-11-01

    Deep brain stimulation (DBS) is a reversible surgical procedure that involves stereotactic implantation of electrodes into the targeted brain regions, with a subcutaneously placed pulse generator powering the electrodes via one or two leads. The mechanism of action can be explained by the stimulation-induced modulation of impaired network activity. So far, the main use of DBS has been for neurological conditions, such as essential tremor, motor symptoms in Parkinson's disease, dystonia, epilepsy, and chronic pain. In psychiatry, case series and open studies indicate treatment efficacy of DBS in Gilles de la Tourette syndrome, treatment-resistant obsessive-compulsive disorder, and refractory major depression. Neuroimaging studies have confirmed the effects of DBS on the brain regions implicated in specific neuropsychiatric disorders. It is a well-tolerated method with relatively few serious side effects. Additional well-designed and appropriately powered controlled clinical trials are needed to conclusively establish the efficacy and safety of DBS and to identify the patient population(s) who may benefit most. Ongoing research with stimulation techniques may also significantly contribute to our understanding of major neuropsychiatric disorders.

  16. Vagus Nerve Stimulation for Treating Epilepsy

    Science.gov (United States)

    ... and their FAMILIES VAGUS NERVE STIMULATION FOR TREATING EPILEPSY This information sheet is provided to help you ... how vagus nerve stimulation (VNS) may help treat epilepsy. The American Academy of Neurology (AAN) is the ...

  17. Follicle-stimulating hormone (FSH) blood test

    Science.gov (United States)

    ... ency/article/003710.htm Follicle-stimulating hormone (FSH) blood test To use the sharing features on this page, please enable JavaScript. The follicle stimulating hormone (FSH) blood test measures the level of FSH in blood. FSH ...

  18. Design of optical switches by illusion optics

    International Nuclear Information System (INIS)

    Shoorian, H R; Abrishamian, M S

    2013-01-01

    In this paper, illusion optics theory is employed to form Bragg gratings in an optical waveguide in order to design an optical switch. By using an illusion device at a certain distance from the waveguide, the effective refractive index of the waveguide is remotely modulated, turning the waveguide into a distributed Bragg reflector (DBR) which blocks the waves at a stop band. By removing the illusion device, the waves propagate through the waveguide again. In addition, this method is used to remotely tune DBR optical properties such as resonant frequency and bandwidth in a wide range, which leads to a tunable filter for optical switching applications. Finally, using an illusion device at a distance, an optical cavity is created by inserting defects remotely in a DBR without any physical damage in the primary device. (paper)

  19. Design of optical switches by illusion optics

    Science.gov (United States)

    Shoorian, H. R.; Abrishamian, M. S.

    2013-05-01

    In this paper, illusion optics theory is employed to form Bragg gratings in an optical waveguide in order to design an optical switch. By using an illusion device at a certain distance from the waveguide, the effective refractive index of the waveguide is remotely modulated, turning the waveguide into a distributed Bragg reflector (DBR) which blocks the waves at a stop band. By removing the illusion device, the waves propagate through the waveguide again. In addition, this method is used to remotely tune DBR optical properties such as resonant frequency and bandwidth in a wide range, which leads to a tunable filter for optical switching applications. Finally, using an illusion device at a distance, an optical cavity is created by inserting defects remotely in a DBR without any physical damage in the primary device.

  20. Nonlinear carrier dynamics in a quantum dash optical amplifier

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Ek, Sara; Yvind, Kresten

    2012-01-01

    Results of experimental pump-probe spectroscopy of a quantum dash optical amplifier biased at transparency are presented. Using strong pump pulses we observe a competition between free carrier absorption and two-photon induced stimulated emission that can have drastic effects on the transmission...

  1. Optical transmission through a polarization preserving single mode optical fiber at two Ar(+) laser wavelengths

    Science.gov (United States)

    Tedjojuwono, Ken K.; Hunter, William W., Jr.

    1989-01-01

    The transmission characteristics of two Ar(+) laser wavelengths through a twenty meter Panda type Polarization Preserving Single Mode Optical Fiber (PPSMOF) were measured. The measurements were done with both single and multi-longitudinal mode radiation. In the single longitudinal mode case, a degrading Stimulated Brillouin Scattering (SBS) is observed as a backward scattering loss. By choosing an optimum coupling system and manipulating the input polarization, the threshold of the SBS onset can be raised and the transmission efficiency can be increased.

  2. A mm-Sized Wireless Implantable Device for Electrical Stimulation of Peripheral Nerves.

    Science.gov (United States)

    Charthad, Jayant; Chang, Ting Chia; Liu, Zhaokai; Sawaby, Ahmed; Weber, Marcus J; Baker, Sam; Gore, Felicity; Felt, Stephen A; Arbabian, Amin

    2018-04-01

    A wireless electrical stimulation implant for peripheral nerves, achieving >10× improvement over state of the art in the depth/volume figure of merit, is presented. The fully integrated implant measures just 2 mm × 3 mm × 6.5 mm (39 mm 3 , 78 mg), and operates at a large depth of 10.5 cm in a tissue phantom. The implant is powered using ultrasound and includes a miniaturized piezoelectric receiver (piezo), an IC designed in 180 nm HV BCD process, an off-chip energy storage capacitor, and platinum stimulation electrodes. The package also includes an optional blue light-emitting diode for potential applications in optogenetic stimulation in the future. A system-level design strategy for complete operation of the implant during the charging transient of the storage capacitor, as well as a unique downlink command/data transfer protocol, is presented. The implant enables externally programmable current-controlled stimulation of peripheral nerves, with a wide range of stimulation parameters, both for electrical (22 to 5000 μA amplitude, ∼14 to 470 μs pulse-width, 0 to 60 Hz repetition rate) and optical (up to 23 mW/mm 2 optical intensity) stimulation. Additionally, the implant achieves 15 V compliance voltage for chronic applications. Full integration of the implant components, end-to-end in vitro system characterizations, and results for the electrical stimulation of a sciatic nerve, demonstrate the feasibility and efficacy of the proposed stimulator for peripheral nerves.

  3. Prenatal music stimulation facilitates the postnatal functional ...

    Indian Academy of Sciences (India)

    2014-01-27

    Jan 27, 2014 ... two main groups: 1. Control – incubated without any auditory stimulation and. 2. Sitar music stimulated – incubated with slow and fast sitar music. Therefore, the experimental paradigm as described by. Jain et al. (2004) for the sound stimulation was followed. Briefly, first sounds of low to mid frequencies, i.e. ...

  4. Modeling and Field Results from Seismic Stimulation

    International Nuclear Information System (INIS)

    Majer, E.; Pride, S.; Lo, W.; Daley, T.; Nakagawa, Seiji; Sposito, Garrison; Roberts, P.

    2006-01-01

    Modeling the effect of seismic stimulation employing Maxwell-Boltzmann theory shows that the important component of stimulation is mechanical rather than fluid pressure effects. Modeling using Biot theory (two phases) shows that the pressure effects diffuse too quickly to be of practical significance. Field data from actual stimulation will be shown to compare to theory

  5. Geothermal Reservoir Well Stimulation Program: technology transfer

    Energy Technology Data Exchange (ETDEWEB)

    1980-05-01

    Each of the following types of well stimulation techniques are summarized and explained: hydraulic fracturing; thermal; mechanical, jetting, and drainhole drilling; explosive and implosive; and injection methods. Current stimulation techniques, stimulation techniques for geothermal wells, areas of needed investigation, and engineering calculations for various techniques. (MHR)

  6. A Chip for an Implantable Neural Stimulator

    DEFF Research Database (Denmark)

    Gudnason, Gunnar; Bruun, Erik; Haugland, Morten

    2000-01-01

    This paper describes a chip for a multichannel neural stimulator for functional electrical stimulation (FES). The purpose of FES is to restore muscular control in disabled patients. The chip performs all the signal processing required in an implanted neural stimulator. The power and digital data...

  7. Nonlinear Optics and Applications

    Science.gov (United States)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  8. A generalized non-local optical response theory for plasmonic nanostructures

    DEFF Research Database (Denmark)

    Mortensen, N. Asger; Raza, Søren; Wubs, Martijn

    2014-01-01

    Metallic nanostructures exhibit a multitude of optical resonances associated with localized surface plasmon excitations. Recent observations of plasmonic phenomena at the sub-nanometre to atomic scale have stimulated the development of various sophisticated theoretical approaches...... for their description. Here instead we present a comparatively simple semiclassical generalized non-local optical response theory that unifies quantum pressure convection effects and induced charge diffusion kinetics, with a concomitant complex-valued generalized non-local optical response parameter. Our theory...

  9. Three-dimensional STED microscopy of aberrating tissue using dual adaptive optics.

    Science.gov (United States)

    Patton, Brian R; Burke, Daniel; Owald, David; Gould, Travis J; Bewersdorf, Joerg; Booth, Martin J

    2016-04-18

    When imaging through tissue, the optical inhomogeneities of the sample generate aberrations that can prevent effective Stimulated Emission Depletion (STED) imaging. This is particularly problematic for 3D-enhanced STED. We present here an adaptive optics implementation that incorporates two adaptive optic elements to enable correction in all beam paths, allowing performance improvement in thick tissue samples. We use this to demonstrate 3D STED imaging of complex structures in Drosophila melanogaster brains.

  10. Model study of combined electrical and near-infrared neural stimulation on the bullfrog sciatic nerve.

    Science.gov (United States)

    You, Mengxian; Mou, Zongxia

    2017-07-01

    This paper implemented a model study of combined electrical and near-infrared (808 nm) neural stimulation (NINS) on the bullfrog sciatic nerve. The model includes a COMSOL model to calculate the electric-field distribution of the surrounding area of the nerve, a Monte Carlo model to simulate light transport and absorption in the bullfrog sciatic nerve during NINS, and a NEURON model to simulate the neural electrophysiology changes under electrical stimulus and laser irradiation. The optical thermal effect is considered the main mechanism during NINS. Therefore, thermal change during laser irradiation was calculated by the Monte Carlo method, and the temperature distribution was then transferred to the NEURON model to stimulate the sciatic nerve. The effects on thermal response by adjusting the laser spot size, energy of the beam, and the absorption coefficient of the nerve are analyzed. The effect of the ambient temperature on the electrical stimulation or laser stimulation and the interaction between laser irradiation and electrical stimulation are also studied. The results indicate that the needed stimulus threshold for neural activation or inhibition is reduced by laser irradiation. Additionally, the needed laser energy for blocking the action potential is reduced by electrical stimulus. Both electrical and laser stimulation are affected by the ambient temperature. These results provide references for subsequent animal experiments and could be of great help to future basic and applied studies of infrared neural stimulation (INS).

  11. Peripheral optogenetic stimulation induces whisker movement and sensory perception in head-fixed mice.

    Science.gov (United States)

    Park, Sunmee; Bandi, Akhil; Lee, Christian R; Margolis, David J

    2016-06-08

    We discovered that optical stimulation of the mystacial pad in Emx1-Cre;Ai27D transgenic mice induces whisker movements due to activation of ChR2 expressed in muscles controlling retraction and protraction. Using high-speed videography in anesthetized mice, we characterize the amplitude of whisker protractions evoked by varying the intensity, duration, and frequency of optogenetic stimulation. Recordings from primary somatosensory cortex (S1) in anesthetized mice indicated that optogenetic whisker pad stimulation evokes robust yet longer latency responses than mechanical whisker stimulation. In head-fixed mice trained to report optogenetic whisker pad stimulation, psychometric curves showed similar dependence on stimulus duration as evoked whisker movements and S1 activity. Furthermore, optogenetic stimulation of S1 in expert mice was sufficient to substitute for peripheral stimulation. We conclude that whisker protractions evoked by optogenetic activation of whisker pad muscles results in cortical activity and sensory perception, consistent with the coding of evoked whisker movements by reafferent sensory input.

  12. High-speed stimulated Brillouin scattering spectroscopy at 780 nm

    Directory of Open Access Journals (Sweden)

    Itay Remer

    2016-09-01

    Full Text Available We demonstrate a high-speed stimulated Brillouin scattering (SBS spectroscopy system that is able to acquire stimulated Brillouin gain point-spectra in water samples and Intralipid tissue phantoms over 2 GHz within 10 ms and 100 ms, respectively, showing a 10-100 fold increase in acquisition rates over current frequency-domain SBS spectrometers. This improvement was accomplished by integrating an ultra-narrowband hot rubidium-85 vapor notch filter in a simplified frequency-domain SBS spectrometer comprising nearly counter-propagating continuous-wave pump-probe light at 780 nm and conventional single-modulation lock-in detection. The optical notch filter significantly suppressed stray pump light, enabling detection of stimulated Brillouin gain spectra with substantially improved acquisition times at adequate signal-to-noise ratios (∼25 dB in water samples and ∼15 dB in tissue phantoms. These results represent an important step towards the use of SBS spectroscopy for high-speed measurements of Brillouin gain resonances in scattering and non-scattering samples.

  13. Optical mapping of optogenetically shaped cardiac action potentials

    Science.gov (United States)

    Park, Sarah A.; Lee, Shin-Rong; Tung, Leslie; Yue, David T.

    2014-01-01

    Light-mediated silencing and stimulation of cardiac excitability, an important complement to electrical stimulation, promises important discoveries and therapies. To date, cardiac optogenetics has been studied with patch-clamp, multielectrode arrays, video microscopy, and an all-optical system measuring calcium transients. The future lies in achieving simultaneous optical acquisition of excitability signals and optogenetic control, both with high spatio-temporal resolution. Here, we make progress by combining optical mapping of action potentials with concurrent activation of channelrhodopsin-2 (ChR2) or halorhodopsin (eNpHR3.0), via an all-optical system applied to monolayers of neonatal rat ventricular myocytes (NRVM). Additionally, we explore the capability of ChR2 and eNpHR3.0 to shape action-potential waveforms, potentially aiding the study of short/long QT syndromes that result from abnormal changes in action potential duration (APD). These results show the promise of an all-optical system to acquire action potentials with precise temporal optogenetics control, achieving a long-sought flexibility beyond the means of conventional electrical stimulation. PMID:25135113

  14. Introduction to nonimaging optics

    CERN Document Server

    Chaves, Julio

    2015-01-01

    Introduction to Nonimaging Optics covers the theoretical foundations and design methods of nonimaging optics, as well as key concepts from related fields. This fully updated, revised, and expanded Second Edition: Features a new and intuitive introduction with a basic description of the advantages of nonimaging opticsAdds new chapters on wavefronts for a prescribed output (irradiance or intensity), infinitesimal étendue optics (generalization of the aplanatic optics), and Köhler optics and color mixingIncorporates new material on the simultaneous multiple surface (SMS) design method in 3-D, int

  15. From optics testing to micro optics testing

    Science.gov (United States)

    Brock, Christian; Dorn, Ralf; Pfund, Johannes

    2017-10-01

    Testing micro optics, i.e. lenses with dimensions down to 0.1mm and less, with high precision requires a dedicated design of the testing device, taking into account propagation and wave-optical effects. In this paper, we discuss testing methods based on Shack-Hartmann wavefront technology for functional testing in transmission and for the measurement of surface shape in reflection. As a first example of more conventional optics testing, i.e. optics in the millimeter range, we present the measurement of binoculars in transmission, and discuss the measured wave aberrations and imaging quality. By repeating the measurement at different wavelengths, information on chromatic effects is retrieved. A task that is often tackled using Shack-Hartman wavefront sensors is the alignment of collimation optics in front of a light source. In case of a micro-optical collimation unit with a 1/e² beam diameter of ca. 1mm, we need adapted relay optics for suitable beam expansion and well-defined imaging conditions. In this example, we will discuss the alignment process and effects of the relay optics magnification, as well as typical performance data. Oftentimes, micro optics are fabricated not as single pieces, but as mass optics, e.g. by lithographic processes. Thus, in order to reduce tooling and alignment time, an automated test procedure is necessary. We present an approach for the automated testing of wafer- or tray-based micro optics, and discuss transmission and reflection measurement capabilities. Exemplary performance data is shown for a sample type with 30 microns in diameter, where typical repeatabilities of a few nanometers (rms) are reached.

  16. Miniature Optical Isolator, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — To address NASA's need for miniature optical isolators in atom interferometry applications, Physical Optics Corporation (POC) proposes to develop a miniature optical...

  17. Stimulated emission and lasing from all-inorganic perovskite quantum dots

    Science.gov (United States)

    Sun, Handong; Wang, Yue; Li, Xiaoming; Haibo, Zeng

    We present superior optical gain and lasing properties in a new class of emerging quantum materials, the colloidal all-inorganic cesium lead halide perovskite quantum dots (IPQDs) (CsPbX3, X = Cl, Br, I). Our result has indicated that such material system show combined merits of both colloidal quantum dots and halide perovskites. Low-threshold and ultrastable stimulated emission was demonstrated under atmospheric condition. The flexibility and advantageous optical gain properties of these CsPbX3 IPQDs were manifested by demonstration of an optically pumped micro-laser. The nonlinear optical properties including the multi-photon absorption and resultant photoluminescence of the CsPbX3 nanocrystals were investigated. A large two-photon absorption cross-section of up to ~1.2×105 GM is determined from 9 nm-sized CsPbBr3 nanocrystals. Moreover, low-threshold frequency-upconverted stimulated emission by two-photon absorption was observed from the thin films of close-packed CsPbBr3 nanocrystals. We further realize the three-photon pumped stimulated emission in green spectra range from colloidal IPQD.

  18. Peptide Optical waveguides.

    Science.gov (United States)

    Handelman, Amir; Apter, Boris; Shostak, Tamar; Rosenman, Gil

    2017-02-01

    Small-scale optical devices, designed and fabricated onto one dielectric substrate, create integrated optical chip like their microelectronic analogues. These photonic circuits, based on diverse physical phenomena such as light-matter interaction, propagation of electromagnetic waves in a thin dielectric material, nonlinear and electro-optical effects, allow transmission, distribution, modulation, and processing of optical signals in optical communication systems, chemical and biological sensors, and more. The key component of these optical circuits providing both optical processing and photonic interconnections is light waveguides. Optical confinement and transmitting of the optical waves inside the waveguide material are possible due to the higher refractive index of the waveguides in comparison with their surroundings. In this work, we propose a novel field of bionanophotonics based on a new concept of optical waveguiding in synthetic elongated peptide nanostructures composed of ordered peptide dipole biomolecules. New technology of controllable deposition of peptide optical waveguiding structures by nanofountain pen technique is developed. Experimental studies of refractive index, optical transparency, and linear and nonlinear waveguiding in out-of-plane and in-plane diphenylalanine peptide nanotubes have been conducted. Optical waveguiding phenomena in peptide structures are simulated by the finite difference time domain method. The advantages of this new class of bio-optical waveguides are high refractive index contrast, wide spectral range of optical transparency, large optical nonlinearity, and electro-optical effect, making them promising for new applications in integrated multifunctional photonic circuits. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  19. Thermally stimulated scattering in plasmas

    DEFF Research Database (Denmark)

    Dysthe, K. B.; Mjølhus, E.; Pécseli, H. L.

    1985-01-01

    this experiment local heat conduction is of little importance and the dynamic evolution for the electron temperature is dominated by heating and energy exchange with the ion component. These features are incorporated in the analysis. The resulting set of equations gives a growth rate and characteristic scale size......A theory for stimulated scattering of a laser beam is formulated where the dominant nonlinearity is the ohmic heating of the plasma. The analysis is carried out with particular reference to experimental investigations of CO2 laser heating of linear discharge plasma. In the conditions characterizing...

  20. Stimulated transitions in resonant atom Majorana mixing

    Science.gov (United States)

    Bernabéu, José; Segarra, Alejandro

    2018-02-01

    Massive neutrinos demand to ask whether they are Dirac or Majorana particles. Majorana neutrinos are an irrefutable proof of physics beyond the Standard Model. Neutrinoless double electron capture is not a process but a virtual Δ L = 2 mixing between a parent A Z atom and a daughter A ( Z - 2) excited atom with two electron holes. As a mixing between two neutral atoms and the observable signal in terms of emitted two-hole X-rays, the strategy, experimental signature and background are different from neutrinoless double beta decay. The mixing is resonantly enhanced for almost degeneracy and, under these conditions, there is no irreducible background from the standard two-neutrino channel. We reconstruct the natural time history of a nominally stable parent atom since its production either by nature or in the laboratory. After the time periods of atom oscillations and the decay of the short-lived daughter atom, at observable times the relevant "stationary" states are the mixed metastable long-lived state and the non-orthogonal short-lived excited state, as well as the ground state of the daughter atom. We find that they have a natural population inversion which is most appropriate for exploiting the bosonic nature of the observed atomic transitions radiation. Among different observables of the atom Majorana mixing, we include the enhanced rate of stimulated X-ray emission from the long-lived metastable state by a high-intensity X-ray beam: a gain factor of 100 can be envisaged at current XFEL facilities. On the other hand, the historical population of the daughter atom ground state can be probed by exciting it with a current pulsed optical laser, showing the characteristic absorption lines: the whole population can be excited in a shorter time than typical pulse duration.

  1. Optical Airborne Tracker System

    Data.gov (United States)

    National Aeronautics and Space Administration — The Optical Airborne Tracker System (OATS) is an airborne dual-axis optical tracking system capable of pointing at any sky location or ground target.  The objectives...

  2. The Scanning Optical Microscope.

    Science.gov (United States)

    Sheppard, C. J. R.

    1978-01-01

    Describes the principle of the scanning optical microscope and explains its advantages over the conventional microscope in the improvement of resolution and contrast, as well as the possibility of producing a picture from optical harmonies generated within the specimen.

  3. Optics for SIERRA

    Data.gov (United States)

    National Aeronautics and Space Administration — To demonstrate a massively parallel optical ray trace to enable the design and analysis of extremely large aperture optical systems. This, in turn, enables...

  4. Fiber Optics Technology.

    Science.gov (United States)

    Burns, William E.

    1986-01-01

    Discusses various applications of fiber optics technology: information systems, industrial robots, medicine, television, transportation, and training. Types of jobs that will be available with fiber optics training (such as electricians and telephone cable installers and splicers) are examined. (CT)

  5. Fiber Optics Instrumentation Development

    Science.gov (United States)

    Chan, Patrick Hon Man; Parker, Allen R., Jr.; Richards, W. Lance

    2010-01-01

    This is a general presentation of fiber optics instrumentation development work being conducted at NASA Dryden for the past 10 years and recent achievements in the field of fiber optics strain sensors.

  6. Optical illusion: apogee development

    OpenAIRE

    Elena, Chernyсhuk; Bazylevych, Viktoriya

    2015-01-01

    The article provides a classification of optical illusions performed by the authors. Briefly described each of the 11 identified species. Offered the variants using optical illusions in the urban environment, exterior and interior.

  7. Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y.; Wuu, Cheng-Shie; Maryanski, Marek J. [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States); Department of Radiation Oncology, Columbia University, New York, New York 10032 and MGS Research Inc., Madison, Connecticut 06443 (United States)

    2010-02-15

    The dose response of the BANG 3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurements on the 18 glass vials irradiated with graded doses from 0 to 4 Gy using 6 or 10 MV large field irradiations; (b) optical-CT scanning of Barex cylinders irradiated with graded doses (0.5, 1, 1.5, and 2 Gy) from four adjacent 4x4 cm{sup 2} photon fields or 6x6 cm{sup 2} electron fields; and (c) percent depth dose (PDD) comparison of optical-CT scans with ion chamber measurements for 6x6 cm{sup 2}, 12 and 16 MeV electron fields. The dose response of the BANG 3 gel was found to be linear and energy independent within the uncertainties of the experimental methods (about 3%). The slopes of the linearly fitted dose response curves (dose sensitivities) from the four field irradiations (0.0752{+-}3%, 0.0756{+-}3%, 0.0767{+-}3%, and 0.0759{+-}3% cm{sup -1} Gy{sup -1}) and the PDD matching methods (0.0768{+-}3% and 0.0761{+-}3% cm{sup -1} Gy{sup -1}) agree within 2.2%, indicating a good reproducibility of the gel dose response within phantoms of the same geometry. The dose sensitivities from the glass vial approach are different from those of the cylindrical Barex phantoms by more than 30%, owing probably to the difference in temperature inside the two types of phantoms during gel formation and irradiation, and possible oxygen contamination of the glass vial walls. The dose response curve obtained from the PDD matching approach with 16 MeV electron field was used to calibrate the gel phantom irradiated with the 12 MeV, 6x6 cm{sup 2} electron field. Three-dimensional dose distributions

  8. Therapeutic electrical stimulation of injured peripheral nerve tissue using implantable thin-film wireless nerve stimulators.

    Science.gov (United States)

    MacEwan, Matthew R; Gamble, Paul; Stephen, Manu; Ray, Wilson Z

    2018-02-09

    OBJECTIVE Electrical stimulation of peripheral nerve tissue has been shown to accelerate axonal regeneration. Yet existing methods of applying electrical stimulation to injured peripheral nerves have presented significant barriers to clinical translation. In this study, the authors examined the use of a novel implantable wireless nerve stimulator capable of simultaneously delivering therapeutic electrical stimulation of injured peripheral nerve tissue and providing postoperative serial assessment of functional recovery. METHODS Flexible wireless stimulators were fabricated and implanted into Lewis rats. Thin-film implants were used to deliver brief electrical stimulation (1 hour, 20 Hz) to sciatic nerves after nerve crush or nerve transection-and-repair injuries. RESULTS Electrical stimulation of injured nerves via implanted wireless stimulators significantly improved functional recovery. Brief electrical stimulation was observed to increase the rate of functional recovery after both nerve crush and nerve transection-and-repair injuries. Wireless stimulators successfully facilitated therapeutic stimulation of peripheral nerve tissue and serial assessment of nerve recovery. CONCLUSIONS Implantable wireless stimulators can deliver therapeutic electrical stimulation to injured peripheral nerve tissue. Implantable wireless nerve stimulators might represent a novel means of facilitating therapeutic electrical stimulation in both intraoperative and postoperative settings.

  9. Braille line using electrical stimulation

    International Nuclear Information System (INIS)

    Puertas, A; Pures, P; Echenique, A M; Ensinck, J P Graffigna y G

    2007-01-01

    Conceived within the field of Rehabilitation Technologies for visually impaired persons, the present work aims at enabling the blind user to read written material by means of a tactile display. Once he is familiarized to operate this system, the user will be able to achieve greater performance in study, academic and job activities, thus achieving a rapid and easier social inclusion. The devise accepts any kind of text that is computer-loadable (documents, books, Internet information, and the like) which, through digital means, can be read as Braille text on the pad. This tactile display is composed of an electrodes platform that simulate, through stimulation the writing/reading Braille characters. In order to perceive said characters in similar way to the tactile feeling from paper material, the skin receptor of fingers are stimulated electrically so as to simulate the same pressure and depressions as those of the paper-based counterpart information. Once designed and developed, the display was tested with blind subjects, with relatively satisfactory results. As a continuing project, this prototype is currently being improved as regards

  10. Advanced digital optical communications

    CERN Document Server

    Binh, Le Nguyen

    2015-01-01

    This book provides a fundamental understanding of digital communication applications in optical communication technologies. Emphasizing operation principles versus mathematical analysis, the Second Edition includes new coverage of superchannel optical transmission systems, metropolitan and long-haul optical systems and networks, and Nyquist pulse shaping and high spectral efficiency of optical transmission systems, as well as new homework problems and examples. Featuring theoretical foundations as well as practical case studies, the text focuses on enhancements to digital technologies that are

  11. Emerging Correlation Optics

    DEFF Research Database (Denmark)

    Angelsky, Oleg V.; Gbur, Gregory J.; Polyanskii, Peter

    2012-01-01

    This feature issue of Applied Optics contains a series of selected papers reflecting the state-of-the-art of correlation optics and showing synergetics between the theoretical background and experimental techniques.......This feature issue of Applied Optics contains a series of selected papers reflecting the state-of-the-art of correlation optics and showing synergetics between the theoretical background and experimental techniques....

  12. Progress in optics

    CERN Document Server

    Wolf, Emil

    2009-01-01

    In the fourty-seven years that have gone by since the first volume of Progress in Optics was published, optics has become one of the most dynamic fields of science. The volumes in this series which have appeared up to now contain more than 300 review articles by distinguished research workers, which have become permanent records for many important developments.- Backscattering and Anderson localization of light- Advances in oliton manipulation in optical lattices- Fundamental quantum noise in optical amplification- Invisibility cloaks

  13. Infrared neural stimulation (INS) inhibits electrically evoked neural responses in the deaf white cat

    Science.gov (United States)

    Richter, Claus-Peter; Rajguru, Suhrud M.; Robinson, Alan; Young, Hunter K.

    2014-03-01

    Infrared neural stimulation (INS) has been used in the past to evoke neural activity from hearing and partially deaf animals. All the responses were excitatory. In Aplysia californica, Duke and coworkers demonstrated that INS also inhibits neural responses [1], which similar observations were made in the vestibular system [2, 3]. In deaf white cats that have cochleae with largely reduced spiral ganglion neuron counts and a significant degeneration of the organ of Corti, no cochlear compound action potentials could be observed during INS alone. However, the combined electrical and optical stimulation demonstrated inhibitory responses during irradiation with infrared light.

  14. Stimulated luminescence of AlN ceramics induced by ultraviolet radiation

    DEFF Research Database (Denmark)

    Trinkler, L.; Bøtter-Jensen, L.; Christensen, P.

    2001-01-01

    Properties of thermally stimulated luminescence (TL) and optically stimulated luminescence (OSL) of the ceramic material A1N-Y2O3 have been studied after exposure to ultraviolet radiation (UVR). The dosemeter material Al2O3 : C has been used for comparative measurements. The spectral sensitivity...... than that of Al2O3 : C in a broad spectral region. The possibility of using A1N-Y2O3 ceramic for UVR dosimetry is discussed. (C) 2001 Elsevier Science Ltd. All rights reserved....

  15. Thermally stimulated nonlinear refraction in gelatin stabilized Cu-PVP nanocomposite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tamgadge, Y. S., E-mail: ystamgadge@gmail.com; Atkare, D. V. [Department of Physics, Mahatma Fule Arts, Commerce & SitaramjiChoudhari Science College, Warud, Dist. Amravati (MS), India-444906 (India); Pahurkar, V. G.; Muley, G. G., E-mail: gajananggm@yahoo.co.in [Department of Physics, SantGadge Baba Amravati University, Amravati (MS), India-444602 (India); Talwatkar, S. S. [Department of Physics, D K Marathe and N G Acharya College, Chembur, Mumbai (MS), India-440071 (India); Sunatkari, A. L. [Department of Physics, Siddharth College of Arts, Science and Commerce, Fort, Mumbai (MS), India-440001 (India)

    2016-05-06

    This article illustrates investigations on thermally stimulated third order nonlinear refraction of Cu-PVP nanocomposite thin films. Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD) and Ultraviolet-visible (UV-vis) spectroscopyfor structural and linear optical studies. Third order nonlinear refraction studies have been performed using closed aperture z-scan technique under continuous wave (CW) He-Ne laser. Cu-PVP nanocomposites are found to exhibit strong nonlinear refractive index stimulated by thermal lensing effect.

  16. LM-OSL signals from some insulators: an analysis of the dependency of the detrapping probability on stimulation light intensity

    DEFF Research Database (Denmark)

    Bulur, E.; Bøtter-Jensen, L.; Murray, A.S.

    2001-01-01

    Optically stimulated luminescence (OSL) signals from various insulators including quartz, Al2O3 : C, BeO and NaCl have been studied using the linear modulation OSL (LM-OSL) technique. LM-OSL is based on the linear increase of the stimulation light power from zero to a maximum during the measurement...... is not always correct. The initial decay rates of the blue (similar to 470 nm) light stimulated constant power OSL decay curves were examined to test the relation between the detrapping rates and the stimulation light intensity. In SiO2, Al2O3 : C and BeO a linear relation between the detrapping rates....... The resultant OSL curve initially increases and then decays after reaching a maximum, The analysis of LM-OSL data usually assumes a linear relationship between the detrapping rate and the stimulation light intensity. However, experiments carried out using various insulators have shown that this assumption...

  17. Progress in optics

    CERN Document Server

    Wolf, Emil

    2015-01-01

    The Progress in Optics series contains more than 300 review articles by distinguished research workers, which have become permanent records for many important developments, helping optical scientists and optical engineers stay abreast of their fields. Comprehensive, in-depth reviewsEdited by the leading authority in the field

  18. Multiplane optical microscope

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wang, Yuan; Zhang, Xiang

    2017-11-21

    This disclosure provides systems, methods, and apparatus related to optical microscopy. In one aspect, an apparatus includes a sample holder, a first objective lens, a plurality of optical components, a second objective lens, and a mirror. The apparatus may directly image a cross-section of a sample oblique to or parallel to the optical axis of the first objective lens, without scanning.

  19. Fun with Optical Fibres

    Science.gov (United States)

    Alti, Kamlesh

    2017-01-01

    Optical fibres play a very crucial role in today's technologies. Academic courses in optical fibres start at the undergraduate level. Nevertheless, student's curiosity towards optical fibres starts from the school level. In this paper, some fun experiments have been designed for both school and college students, which have some concrete…

  20. Optical ordinal optimization

    Science.gov (United States)

    Caulfield, H. John

    2000-07-01

    Ordinal optimization is a relatively new field of mathematics that seems never to have been applied to optics. Optics has made extensive use of traditional cardinal optimization. This paper explores the possibility that ordinal optimization might be useful in optics. The conclusion is: Not directly but indirectly.

  1. Spatiotemporal dynamics of cortical perfusion in response to thalamic deep brain stimulation.

    Science.gov (United States)

    Noor, M Sohail; Murari, Kartikeya; McCracken, Clinton B; Kiss, Zelma H T

    2016-02-01

    Deep brain stimulation (DBS) has revolutionized the treatment of movement disorders. The parameters of electrical stimulation are important to its therapeutic effect and remain a source of clinical controversy. DBS exerts its actions not only locally at the site of stimulation but also remotely through afferent and efferent connections, which are vital to its clinical effects. Yet, only a few studies have examined how cortical activity changes in response to various electrical parameters. Here, we investigated how the parameters of thalamic DBS alter cortical perfusion in rats using intrinsic optical imaging. We hypothesized that thalamic DBS will increase perfusion in primary motor cortex (M1), proportional to amplitude, pulse width, or frequency of the stimulation applied. We applied 45 different combinations of amplitude, pulse width and frequency in the ventro-lateral (VL) nucleus of the thalamus in anesthetized rats while measuring perfusion in M1. VL thalamic DBS reduced cortical reflectance, which corresponds to an increase in cortical perfusion. We computed the maximum change in reflectance (MCR) as well as the spatial spread of MCR in each trial. Both MCR and spatial spread increased linearly with increases in current amplitude or pulse width of stimulation; however, the effect of frequency was non-linear. Stimulation at 20 Hz was significantly different from that at higher frequencies while stimulation at higher frequencies did not differ significantly from each other. Moreover, the effect of pulse width on MCR was larger than the effect of amplitude. The proportional increase in M1 perfusion due to increase in amplitude or pulse width suggests that both activate more neural elements and increase the volume of tissue activated. These results should help clinicians set parameters of DBS. The use of optical imaging to monitor effects of DBS on M1 may not only help understand DBS mechanisms, but may also provide feedback for closed loop DBS devices

  2. Electrical stimulation of superior colliculus affects strabismus angle in monkey models for strabismus.

    Science.gov (United States)

    Upadhyaya, Suraj; Meng, Hui; Das, Vallabh E

    2017-03-01

    Disruption of binocular vision during the critical period for development leads to eye misalignment in humans and in monkey models. We have previously suggested that disruption within a vergence circuit could be the neural basis for strabismus. Electrical stimulation in the rostral superior colliculus (rSC) leads to vergence eye movements in normal monkeys. Therefore, the purpose of this study was to investigate the effect of SC stimulation on eye misalignment in strabismic monkeys. Electrical stimulation was delivered to 51 sites in the intermediate and deep layers of the SC (400 Hz, 0.5-s duration, 10-40 μA) in 3 adult optical prism-reared strabismic monkeys. Scleral search coils were used to measure movements of both eyes during a fixation task. Staircase saccades with horizontal and vertical components were elicited by stimulation as predicted from the SC topographic map. Electrical stimulation also resulted in significant changes in horizontal strabismus angle, i.e., a shift toward exotropia/esotropia depending on stimulation site. Electrically evoked saccade vector amplitude in the two eyes was not significantly different ( P > 0.05; paired t -test) but saccade direction differed. However, saccade disconjugacy accounted for only ~50% of the change in horizontal misalignment while disconjugate postsaccadic movements accounted for the other ~50% of the change in misalignment due to electrical stimulation. In summary, our data suggest that electrical stimulation of the SC of strabismic monkeys produces a change in horizontal eye alignment that is due to a combination of disconjugate saccadic eye movements and disconjugate postsaccadic movements. NEW & NOTEWORTHY Electrical stimulation of the superior colliculus in strabismic monkeys results in a change in eye misalignment. These data support the notion of developmental disruption of vergence circuits leading to maintenance of eye misalignment in strabismus. Copyright © 2017 the American Physiological Society.

  3. Electrical stimulation of superior colliculus affects strabismus angle in monkey models for strabismus

    Science.gov (United States)

    Upadhyaya, Suraj; Meng, Hui

    2017-01-01

    Disruption of binocular vision during the critical period for development leads to eye misalignment in humans and in monkey models. We have previously suggested that disruption within a vergence circuit could be the neural basis for strabismus. Electrical stimulation in the rostral superior colliculus (rSC) leads to vergence eye movements in normal monkeys. Therefore, the purpose of this study was to investigate the effect of SC stimulation on eye misalignment in strabismic monkeys. Electrical stimulation was delivered to 51 sites in the intermediate and deep layers of the SC (400 Hz, 0.5-s duration, 10–40 μA) in 3 adult optical prism-reared strabismic monkeys. Scleral search coils were used to measure movements of both eyes during a fixation task. Staircase saccades with horizontal and vertical components were elicited by stimulation as predicted from the SC topographic map. Electrical stimulation also resulted in significant changes in horizontal strabismus angle, i.e., a shift toward exotropia/esotropia depending on stimulation site. Electrically evoked saccade vector amplitude in the two eyes was not significantly different (P > 0.05; paired t-test) but saccade direction differed. However, saccade disconjugacy accounted for only ~50% of the change in horizontal misalignment while disconjugate postsaccadic movements accounted for the other ~50% of the change in misalignment due to electrical stimulation. In summary, our data suggest that electrical stimulation of the SC of strabismic monkeys produces a change in horizontal eye alignment that is due to a combination of disconjugate saccadic eye movements and disconjugate postsaccadic movements. NEW & NOTEWORTHY Electrical stimulation of the superior colliculus in strabismic monkeys results in a change in eye misalignment. These data support the notion of developmental disruption of vergence circuits leading to maintenance of eye misalignment in strabismus. PMID:28031397

  4. Near perfect optics

    Energy Technology Data Exchange (ETDEWEB)

    Goeke, R.; Farnsworth, A.V.; Neumann, C.C.; Sweatt, W.C.; Warren, M.E.; Weed, J.W.

    1996-06-01

    This report discusses a novel fabrication process to produce nearly perfect optics. The process utilizes vacuum deposition techniques to optimally modify polished optical substrate surfaces. The surface figure, i.e. contour of a polished optical element, is improved by differentially filling in the low spots on the surface using flux from a physical vapor deposition source through an appropriate mask. The process is expected to enable the manufacture of diffraction-limited optical systems for the UV, extreme UV, and soft X-ray spectral regions, which would have great impact on photolithography and astronomy. This same technique may also reduce the fabrication cost of visible region optics with aspheric surfaces.

  5. Optical modulator including grapene

    Science.gov (United States)

    Liu, Ming; Yin, Xiaobo; Zhang, Xiang

    2016-06-07

    The present invention provides for a one or more layer graphene optical modulator. In a first exemplary embodiment the optical modulator includes an optical waveguide, a nanoscale oxide spacer adjacent to a working region of the waveguide, and a monolayer graphene sheet adjacent to the spacer. In a second exemplary embodiment, the optical modulator includes at least one pair of active media, where the pair includes an oxide spacer, a first monolayer graphene sheet adjacent to a first side of the spacer, and a second monolayer graphene sheet adjacent to a second side of the spacer, and at least one optical waveguide adjacent to the pair.

  6. Optical Binding of Nanowires

    Czech Academy of Sciences Publication Activity Database

    Simpson, Stephen Hugh; Zemánek, Pavel; Marago, O.M.; Jones, P.H.; Hanna, S.

    2017-01-01

    Roč. 17, č. 6 (2017), s. 3485-3492 ISSN 1530-6984 R&D Projects: GA ČR GB14-36681G Grant - others:AV ČR(CZ) CNR-16-12 Program:Bilaterální spolupráce Institutional support: RVO:68081731 Keywords : optical binding nanowires * Brownian motion * self -organization * non-equilibrium thermodynamics * non-equilibrium steady state * spin-orbit coupling * emergent phenomena Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 12.712, year: 2016

  7. Small scale optics

    CERN Document Server

    Yupapin, Preecha

    2013-01-01

    The behavior of light in small scale optics or nano/micro optical devices has shown promising results, which can be used for basic and applied research, especially in nanoelectronics. Small Scale Optics presents the use of optical nonlinear behaviors for spins, antennae, and whispering gallery modes within micro/nano devices and circuits, which can be used in many applications. This book proposes a new design for a small scale optical device-a microring resonator device. Most chapters are based on the proposed device, which uses a configuration know as a PANDA ring resonator. Analytical and nu

  8. [Adaptive optics for ophthalmology].

    Science.gov (United States)

    Saleh, M

    2016-04-01

    Adaptive optics is a technology enhancing the visual performance of an optical system by correcting its optical aberrations. Adaptive optics have already enabled several breakthroughs in the field of visual sciences, such as improvement of visual acuity in normal and diseased eyes beyond physiologic limits, and the correction of presbyopia. Adaptive optics technology also provides high-resolution, in vivo imaging of the retina that may eventually help to detect the onset of retinal conditions at an early stage and provide better assessment of treatment efficacy. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  9. Optic disc oedema

    DEFF Research Database (Denmark)

    Nielsen, Marianne Kromann; Hamann, Steffen

    2014-01-01

    Optic disc oedema describes the nonspecific, localized swelling of the optic nerve head regardless of aetiology. Therefore, differentiating among the various aetiologies depends on a thorough history and knowledge of the clinical characteristics of the underlying conditions. Papilloedema strictly...... refers to optic disc oedema as a consequence of elevated intracranial pressure. It is usually a bilateral condition and visual function is preserved until late. Optic disc oedema caused by an anterior optic neuropathy is usually unilateral and accompanied by the loss of visual function....

  10. Progress in optics

    CERN Document Server

    Wolf, Emil

    2006-01-01

    In the thirty-seven years that have gone by since the first volume of Progress in Optics was published, optics has become one of the most dynamic fields of science. At the time of inception of this series, the first lasers were only just becoming operational, holography was in its infancy, subjects such as fiber optics, integrated optics and optoelectronics did not exist and quantum optics was the domain of only a few physicists. The term photonics had not yet been coined. Today these fields are flourishing and have become areas of specialisation for many science and engineering students and n

  11. Progress in optics

    CERN Document Server

    Wolf, Emil

    1977-01-01

    In the thirty-seven years that have gone by since the first volume of Progress in Optics was published, optics has become one of the most dynamic fields of science. At the time of inception of this series, the first lasers were only just becoming operational, holography was in its infancy, subjects such as fiber optics, integrated optics and optoelectronics did not exist and quantum optics was the domain of only a few physicists. The term photonics had not yet been coined. Today these fields are flourishing and have become areas of specialisation for many science and engineering students and n

  12. Magnetic-motor-root stimulation: review.

    Science.gov (United States)

    Matsumoto, Hideyuki; Hanajima, Ritsuko; Terao, Yasuo; Ugawa, Yoshikazu

    2013-06-01

    Magnetic stimulation can activate the human central and peripheral nervous systems non-invasively and virtually painlessly. Magnetic stimulation over the spinal enlargements can activate spinal nerves at the neuroforamina (magnetic-neuroforamina stimulation). This stimulation method provides us with information related to the latency of compound-muscle action potential (CMAP), which is usually interpreted as peripheral motor-conduction time (PMCT). However, this stimulation method has faced several problems in clinical applications. One is that supramaximal CMAPs were unobtainable. Another is that magnetic stimulation did not usually activate the spinal nerves in the spinal canal, i.e., the cauda equina, which prevented an evaluation of its conduction. For these reasons, magnetic-neuroforamina stimulation was rarely used to evaluate the conduction of peripheral nerves. It was mainly used to evaluate the conduction of the corticospinal tract using the parameter of central motor-conduction time (CMCT), which was calculated by subtracting PMCT from the latency of motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) over the primary motor cortex. Recently, supramaximal stimulation has been achieved in magnetic-neuroforamina stimulation, and this has contributed to the measurement of both CMAP size and latency. The achievement of supramaximal stimulation is ascribed to the increase in magnetic-stimulator output and a novel coil, the magnetic augmented translumbosacral stimulation (MATS) coil. The most proximal part of the cauda equina can be reliably activated using the MATS coil (magnetic-conus stimulation), thus contributing to the measurement of cauda equina conduction time (CECT) and cortico-conus motor-conduction time (CCCT). These recent developments in magnetic-motor-root stimulation enable us to more precisely evaluate the conduction of the proximal part of peripheral nerves and that of the corticospinal tract for lower-limb muscles

  13. Behavioural modification of the optic tentacle of Helix pom atia; effect of puromycin, activity of S-100

    DEFF Research Database (Denmark)

    Christoffersen, Gert Rene Juul; Frederiksen, K; Johansen, Jørgen

    1981-01-01

    1. 1. A long-term learning phenomenon in the tentacle of Helix pomatia has been observed.   2. 2. Repeated mechanical stimulation of the optic tentacle led to habituation of the associated withdrawal-extension action pattern whereas repeated combined mechanical and electrical stimulation...

  14. Peptide Integrated Optics.

    Science.gov (United States)

    Handelman, Amir; Lapshina, Nadezda; Apter, Boris; Rosenman, Gil

    2018-02-01

    Bio-nanophotonics is a wide field in which advanced optical materials, biomedicine, fundamental optics, and nanotechnology are combined and result in the development of biomedical optical chips. Silk fibers or synthetic bioabsorbable polymers are the main light-guiding components. In this work, an advanced concept of integrated bio-optics is proposed, which is based on bioinspired peptide optical materials exhibiting wide optical transparency, nonlinear and electrooptical properties, and effective passive and active waveguiding. Developed new technology combining bottom-up controlled deposition of peptide planar wafers of a large area and top-down focus ion beam lithography provides direct fabrication of peptide optical integrated circuits. Finding a deep modification of peptide optical properties by reconformation of biological secondary structure from native phase to β-sheet architecture is followed by the appearance of visible fluorescence and unexpected transition from a native passive optical waveguiding to an active one. Original biocompatibility, switchable regimes of waveguiding, and multifunctional nonlinear optical properties make these new peptide planar optical materials attractive for application in emerging technology of lab-on-biochips, combining biomedical photonic and electronic circuits toward medical diagnosis, light-activated therapy, and health monitoring. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Socioeconomic evaluation of vagus stimulation

    DEFF Research Database (Denmark)

    Jennum, Poul; Sabers, Anne; Christensen, Jakob

    2016-01-01

    PURPOSE: We aimed to determine the health costs and social outcomes in terms of education, employment and income level after insertion of a vagus nerve stimulator (VNS) in patients with epilepsy. METHODS: This is a case-control study using Danish health care and socioeconomic register data....... The analysis of the effect involved a comparison of the health care costs, occupation and income status of VNS-treated epilepsy patients with those of a control group of epilepsy patients who had a VNS implanted during the 12 months before the index date (pre-period) and during the two years after the index...... implantation. VNS implantation was not associated with changes in occupational status (including employment and income). In fact, the number of people on disability pension increased during the period. CONCLUSIONS: VNS implantation in people with epilepsy is associated with reduced health care use...

  16. Multisensory stimulation in stroke rehabilitation

    Directory of Open Access Journals (Sweden)

    Barbro Birgitta Johansson

    2012-04-01

    Full Text Available The brain has a large capacity for automatic simultaneous processing and integration of sensory information. Combining information from different sensory modalities facilitates our ability to detect, discriminate, and recognize sensory stimuli, and learning is often optimal in a multisensory environment. Currently used multisensory stimulation methods in stroke rehabilitation include motor imagery, action observation, training with a mirror or in a virtual environment, or various kinds of music therapy. Several studies have shown positive effects been reported but to give general recommendation more studies are needed. Patient heterogeneity and the interactions of age, gender, genes and environment are discussed. Randomized controlled longitudinal trials starting earlier post stroke are needed. The advance in brain network science and neuroimaging enabling longitudinal studies of structural and functional networks are likely to have an important impact on patient selection for specific interventions in future stroke rehabilitation.

  17. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  18. Optical logic: an overview

    Science.gov (United States)

    Caulfield, H. John

    2005-05-01

    Progress of optical logic has been anything but uniform or even monotonic. The hope for "all optical computers" was largely abandoned after devastating critiques by Keyes. Over time, optical logic transformed into a very viable niche activity by the needs of optical communication for "all optical" logic and the advent of a critical component: the SOA or Semiconductor Optical Amplifier. I argue that a new phase in this uneven history can be defined - linear (single photon, not multiple entangled photon) quantum optical logic. These can perform conservative, reversible logic operations without energy or time penalties, but cascading requires the irreversible act of measurement, so only single devices or single layers can deliver those advantages.

  19. Optic nerve oxygenation

    DEFF Research Database (Denmark)

    Stefánsson, Einar; Pedersen, Daniella Bach; Jensen, Peter Koch

    2005-01-01

    The oxygen tension of the optic nerve is regulated by the intraocular pressure and systemic blood pressure, the resistance in the blood vessels and oxygen consumption of the tissue. The oxygen tension is autoregulated and moderate changes in intraocular pressure or blood pressure do not affect...... the optic nerve oxygen tension. If the intraocular pressure is increased above 40 mmHg or the ocular perfusion pressure decreased below 50 mmHg the autoregulation is overwhelmed and the optic nerve becomes hypoxic. A disturbance in oxidative metabolism in the cytochromes of the optic nerve can be seen...... at similar levels of perfusion pressure. The levels of perfusion pressure that lead to optic nerve hypoxia in the laboratory correspond remarkably well to the levels that increase the risk of glaucomatous optic nerve atrophy in human glaucoma patients. The risk for progressive optic nerve atrophy in human...

  20. Optic nerve oxygenation

    DEFF Research Database (Denmark)

    Stefánsson, Einar; Pedersen, Daniella Bach; Jensen, Peter Koch

    2005-01-01

    at similar levels of perfusion pressure. The levels of perfusion pressure that lead to optic nerve hypoxia in the laboratory correspond remarkably well to the levels that increase the risk of glaucomatous optic nerve atrophy in human glaucoma patients. The risk for progressive optic nerve atrophy in human...... glaucoma patients is six times higher at a perfusion pressure of 30 mmHg, which corresponds to a level where the optic nerve is hypoxic in experimental animals, as compared to perfusion pressure levels above 50 mmHg where the optic nerve is normoxic. Medical intervention can affect optic nerve oxygen......-oxygenase inhibitor, indomethacin, which indicates that prostaglandin metabolism plays a role. Laboratory studies suggest that carbonic anhydrase inhibitors might be useful for medical treatment of optic nerve and retinal ischemia, potentially in diseases such as glaucoma and diabetic retinopathy. However, clinical...

  1. Optical system design

    CERN Document Server

    Fischer, Robert F

    2008-01-01

    Honed for more than 20 years in an SPIE professional course taught by renowned optical systems designer Robert E. Fischer, Optical System Design, Second Edition brings you the latest cutting-edge design techniques and more than 400 detailed diagrams that clearly illustrate every major procedure in optical design. This thoroughly updated resource helps you work better and faster with computer-aided optical design techniques, diffractive optics, and the latest applications, including digital imaging, telecommunications, and machine vision. No need for complex, unnecessary mathematical derivations-instead, you get hundreds of examples that break the techniques down into understandable steps. For twenty-first century optical design without the mystery, the authoritative Optical Systems Design, Second Edition features: Computer-aided design use explained through sample problems Case studies of third-millennium applications in digital imaging, sensors, lasers, machine vision, and more New chapters on optomechanic...

  2. MEMS optical sensor

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to an all-optical sensor utilizing effective index modulation of a waveguide and detection of a wavelength shift of reflected light and a force sensing system accommodating said optical sensor. One embodiment of the invention relates to a sensor system comprising...... at least one multimode light source, one or more optical sensors comprising a multimode sensor optical waveguide accommodating a distributed Bragg reflector, at least one transmitting optical waveguide for guiding light from said at least one light source to said one or more multimode sensor optical...... waveguides, a detector for measuring light reflected from said Bragg reflector in said one or more multimode sensor optical waveguides, and a data processor adapted for analyzing variations in the Bragg wavelength of at least one higher order mode of the reflected light....

  3. Non-invasive neural stimulation

    Science.gov (United States)

    Tyler, William J.; Sanguinetti, Joseph L.; Fini, Maria; Hool, Nicholas

    2017-05-01

    Neurotechnologies for non-invasively interfacing with neural circuits have been evolving from those capable of sensing neural activity to those capable of restoring and enhancing human brain function. Generally referred to as non-invasive neural stimulation (NINS) methods, these neuromodulation approaches rely on electrical, magnetic, photonic, and acoustic or ultrasonic energy to influence nervous system activity, brain function, and behavior. Evidence that has been surmounting for decades shows that advanced neural engineering of NINS technologies will indeed transform the way humans treat diseases, interact with information, communicate, and learn. The physics underlying the ability of various NINS methods to modulate nervous system activity can be quite different from one another depending on the energy modality used as we briefly discuss. For members of commercial and defense industry sectors that have not traditionally engaged in neuroscience research and development, the science, engineering and technology required to advance NINS methods beyond the state-of-the-art presents tremendous opportunities. Within the past few years alone there have been large increases in global investments made by federal agencies, foundations, private investors and multinational corporations to develop advanced applications of NINS technologies. Driven by these efforts NINS methods and devices have recently been introduced to mass markets via the consumer electronics industry. Further, NINS continues to be explored in a growing number of defense applications focused on enhancing human dimensions. The present paper provides a brief introduction to the field of non-invasive neural stimulation by highlighting some of the more common methods in use or under current development today.

  4. Noninvasive transcranial brain stimulation and pain.

    Science.gov (United States)

    Rosen, Allyson C; Ramkumar, Mukund; Nguyen, Tam; Hoeft, Fumiko

    2009-02-01

    Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are two noninvasive brain stimulation techniques that can modulate activity in specific regions of the cortex. At this point, their use in brain stimulation is primarily investigational; however, there is clear evidence that these tools can reduce pain and modify neurophysiologic correlates of the pain experience. TMS has also been used to predict response to surgically implanted stimulation for the treatment of chronic pain. Furthermore, TMS and tDCS can be applied with other techniques, such as event-related potentials and pharmacologic manipulation, to illuminate the underlying physiologic mechanisms of normal and pathological pain. This review presents a description and overview of the uses of two major brain stimulation techniques and a listing of useful references for further study.

  5. Mimicking muscle activity with electrical stimulation

    Science.gov (United States)

    Johnson, Lise A.; Fuglevand, Andrew J.

    2011-02-01

    Functional electrical stimulation is a rehabilitation technology that can restore some degree of motor function in individuals who have sustained a spinal cord injury or stroke. One way to identify the spatio-temporal patterns of muscle stimulation needed to elicit complex upper limb movements is to use electromyographic (EMG) activity recorded from able-bodied subjects as a template for electrical stimulation. However, this requires a transfer function to convert the recorded (or predicted) EMG signals into an appropriate pattern of electrical stimulation. Here we develop a generalized transfer function that maps EMG activity into a stimulation pattern that modulates muscle output by varying both the pulse frequency and the pulse amplitude. We show that the stimulation patterns produced by this transfer function mimic the active state measured by EMG insofar as they reproduce with good fidelity the complex patterns of joint torque and joint displacement.

  6. Analysis of Facial Expression by Taste Stimulation

    Science.gov (United States)

    Tobitani, Kensuke; Kato, Kunihito; Yamamoto, Kazuhiko

    In this study, we focused on the basic taste stimulation for the analysis of real facial expressions. We considered that the expressions caused by taste stimulation were unaffected by individuality or emotion, that is, such expressions were involuntary. We analyzed the movement of facial muscles by taste stimulation and compared real expressions with artificial expressions. From the result, we identified an obvious difference between real and artificial expressions. Thus, our method would be a new approach for facial expression recognition.

  7. Accuracies Of Optical Processors For Adaptive Optics

    Science.gov (United States)

    Downie, John D.; Goodman, Joseph W.

    1992-01-01

    Paper presents analysis of accuracies and requirements concerning accuracies of optical linear-algebra processors (OLAP's) in adaptive-optics imaging systems. Much faster than digital electronic processor and eliminate some residual distortion. Question whether errors introduced by analog processing of OLAP overcome advantage of greater speed. Paper addresses issue by presenting estimate of accuracy required in general OLAP that yields smaller average residual aberration of wave front than digital electronic processor computing at given speed.

  8. Geothermal Reservoir Well Stimulation Program: technology transfer

    Energy Technology Data Exchange (ETDEWEB)

    1980-05-01

    A literature search on reservoir and/or well stimulation techniques suitable for application in geothermal fields is presented. The literature on stimulation techniques in oil and gas field applications was also searched and evaluated as to its relevancy to geothermal operations. The equivalent low-temperature work documented in the open literature is cited, and an attempt is made to evaluate the relevance of this information as far as high-temperature stimulation work is concerned. Clays play an important role in any stimulation work. Therefore, special emphasis has been placed on clay behavior anticipated in geothermal operations. (MHR)

  9. Stimulant ADHD Medications -- Methylphenidate and Amphetamines

    Science.gov (United States)

    ... prescription stimulants? dextroamphetamine (Dexedrine ® ) dextroamphetamine/amphetamine combination product (Adderall ® ) methylphenidate (Ritalin ® , Concerta ® ). Popular slang terms for prescription ...

  10. Simulation teaching method in Engineering Optics

    Science.gov (United States)

    Lu, Qieni; Wang, Yi; Li, Hongbin

    2017-08-01

    We here introduce a pedagogical method of theoretical simulation as one major means of the teaching process of "Engineering Optics" in course quality improvement action plan (Qc) in our school. Students, in groups of three to five, complete simulations of interference, diffraction, electromagnetism and polarization of light; each student is evaluated and scored in light of his performance in the interviews between the teacher and the student, and each student can opt to be interviewed many times until he is satisfied with his score and learning. After three years of Qc practice, the remarkable teaching and learning effect is obatined. Such theoretical simulation experiment is a very valuable teaching method worthwhile for physical optics which is highly theoretical and abstruse. This teaching methodology works well in training students as to how to ask questions and how to solve problems, which can also stimulate their interest in research learning and their initiative to develop their self-confidence and sense of innovation.

  11. Optical tomography of the neonatal brain

    Energy Technology Data Exchange (ETDEWEB)

    Hebden, Jeremy C. [University College London, Department of Medical Physics and Bioengineering, London (United Kingdom); Austin, Topun [University College London, Department of Paediatrics and Child Health, London (United Kingdom)

    2007-11-15

    A new method of assessing neurological function and pathology in the newborn infant is being developed based on the transmission of near-infrared light across the brain. Absorption by blood over a range of wavelengths reveals a strong dependency on oxygenation status, and measurements of transmitted light enable the spatial variation in the concentrations of the oxygenated and de-oxygenated forms of hemoglobin to be derived. Optical tomography has so far provided static three-dimensional maps of blood volume and oxygenation as well as dynamic images revealing the brain's response to sensory stimulation and global hemodynamic changes. The imaging modality is being developed as a safe and non-invasive tool that can be utilized at the cotside in intensive care. Optical tomography of the healthy infant brain is also providing a means of studying neurophysiological processes during early development and the potential consequences of prematurity. (orig.)

  12. Astrocyte glycogen metabolism is required for neural activity during aglycemia or intense stimulation in mouse white matter

    DEFF Research Database (Denmark)

    Brown, Angus M; Sickmann, Helle M; Fosgerau, Keld

    2005-01-01

    We tested the hypothesis that inhibiting glycogen degradation accelerates compound action potential (CAP) failure in mouse optic nerve (MON) during aglycemia or high-intensity stimulation. Axon function was assessed as the evoked CAP, and glycogen content was measured biochemically. Isofagomine, ...

  13. Cognitive stimulation in healthy older adults: a cognitive stimulation program using leisure activities compared to a conventional cognitive stimulation program.

    Science.gov (United States)

    Grimaud, Élisabeth; Taconnat, Laurence; Clarys, David

    2017-06-01

    The aim of this study was to compare two methods of cognitive stimulation for the cognitive functions. The first method used an usual approach, the second used leisure activities in order to assess their benefits on cognitive functions (speed of processing; working memory capacity and executive functions) and psychoaffective measures (memory span and self esteem). 67 participants over 60 years old took part in the experiment. They were divided into three groups: 1 group followed a program of conventional cognitive stimulation, 1 group a program of cognitive stimulation using leisure activities and 1 control group. The different measures have been evaluated before and after the training program. Results show that the cognitive stimulation program using leisure activities is as effective on memory span, updating and memory self-perception as the program using conventional cognitive stimulation, and more effective on self-esteem than the conventional program. There is no difference between the two stimulated groups and the control group on speed of processing. Neither of the two cognitive stimulation programs provides a benefit over shifting and inhibition. These results indicate that it seems to be possible to enhance working memory and to observe far transfer benefits over self-perception (self-esteem and memory self-perception) when using leisure activities as a tool for cognitive stimulation.

  14. Fibre-optical microendoscopy.

    Science.gov (United States)

    Gu, M; Bao, H; Kang, H

    2014-04-01

    Microendoscopy has been an essential tool in exploring micro/nano mechanisms in vivo due to high-quality imaging performance, compact size and flexible movement. The investigations into optical fibres, micro-scanners and miniature lens have boosted efficiencies of remote light delivery to sample site and signal collection. Given the light interaction with materials in the fluorescence imaging regime, this paper reviews two classes of compact microendoscopy based on a single fibre: linear optical microendoscopy and nonlinear optical microendoscopy. Due to the fact that fluorescence occurs only in the focal volume, nonlinear optical microendoscopy can provide stronger optical sectioning ability than linear optical microendoscopy, and is a good candidate for deep tissue imaging. Moreover, one-photon excited fluorescence microendoscopy as the linear optical microendoscopy suffers from severe photobleaching owing to the linear dependence of photobleaching rate on excitation laser power. On the contrary, nonlinear optical microendoscopy, including two-photon excited fluorescence microendoscopy and second harmonic generation microendoscopy, has the capability to minimize or avoid the photobleaching effect at a high excitation power and generate high image contrast. The combination of various nonlinear signals gained by the nonlinear optical microendoscopy provides a comprehensive insight into biophenomena in internal organs. Fibre-optical microendoscopy overcomes physical limitations of traditional microscopy and opens up a new path to achieve early cancer diagnosis and microsurgery in a minimally invasive and localized manner. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  15. Excitation and emission spectrometry of stimulated luminescence from quartz and feldspars

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Duller, G.A.T.; Poolton N.R.J.

    1994-01-01

    A new scanning monochromator was designed to investigate the wavelength-resolved luminescence excitation and emission characteristics of quartz and feldspar samples; results are presented together with detailed measurements of the thermal activation energies required for luminescence stimulation...... in feldspar over the wavelength range 400-1000 nm. When coupled to automated dating equipment, we demonstrate that optical characteristics of sample selected for dating can be routinely measured, or more detailed analysis of physical processes can be made....

  16. Characterisation of blue-light stimulated luminescence components in different quartz samples: Implications for dose measurement

    DEFF Research Database (Denmark)

    Jain, M.; Murray, A.S.; Bøtter-Jensen, L.

    2003-01-01

    Over the last few years, we have become increasingly confident that quartz is a reliable natural dosimeter for sediment dating. Nevertheless, there is only a limited understanding of the behaviour of the different components of optically stimulated luminescence (OSL) from quartz. Recent single-aliquot...... modulated (LM-OSL) components. We then discuss the implications of these characteristics for dose assessment using the single aliquot regeneration dose protocol. (C) 2003 Elsevier Science Ltd. All rights reserved....

  17. NATO Advanced Study Institute on Nano-Optics : Principles Enabling Basic Research and Applications

    CERN Document Server

    Collins, John; Silvestri, Luciano

    2017-01-01

    This book provides a comprehensive overview of nano-optics, including basic theory, experiment and applications, particularly in nanofabrication and optical characterization. The contributions clearly demonstrate how advances in nano-optics and photonics have stimulated progress in nanoscience and -fabrication, and vice versa. Their expert authors address topics such as three-dimensional optical lithography and microscopy beyond the Abbe diffraction limit, optical diagnostics and sensing, optical data- and telecommunications, energy-efficient lighting, and efficient solar energy conversion. Nano-optics emerges as a key enabling technology of the 21st century. This work will appeal to a wide readership, from physics through chemistry, to biology and engineering. The contributions that appear in this volume were presented at a NATO Advanced Study Institute held in Erice, 4-19 July, 2015.

  18. Optical countermeasures against CLOS weapon systems

    Science.gov (United States)

    Toet, Alexander; Benoist, Koen W.; van Lingen, Joost N. J.; Schleijpen, H. Ric M. A.

    2013-10-01

    There are many weapon systems in which a human operator acquires a target, tracks it and designates it. Optical countermeasures against this type of systems deny the operator the possibility to fulfill this visual task. We describe the different effects that result from stimulation of the human visual system with high intensity (visible) light, and the associated potential operational impact. Of practical use are flash blindness, where an intense flash of light produces a temporary "blind-spot" in (part of) the visual field, flicker distraction, where strong intensity and/or color changes at a discomfortable frequency are produced, and disability glare where a source of light leads to contrast reduction. Hence there are three possibilities to disrupt the visual task of an operator with optical countermeasures such as flares or lasers or a combination of these; namely, by an intense flash of light, by an annoying light flicker or by a glare source. A variety of flares for this purpose is now available or under development: high intensity flash flares, continuous burning flares or strobe flares which have an oscillating intensity. The use of flare arrays seems particularly promising as an optical countermeasure. Lasers are particularly suited to interfere with human vision, because they can easily be varied in intensity, color and size, but they have to be directed at the (human) target, and issues like pointing and eye-safety have to be taken into account. Here we discuss the design issues and the operational impact of optical countermeasures against human operators.

  19. Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots

    NARCIS (Netherlands)

    Geiregat, Pieter; Houtepen, Arjan J.; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; Van Thourhout, Dries; Hens, Zeger

    2017-01-01

    Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be

  20. Optical vector network analyzer with improved accuracy based on polarization modulation and polarization pulling.

    Science.gov (United States)

    Li, Wei; Liu, Jian Guo; Zhu, Ning Hua

    2015-04-15

    We report a novel optical vector network analyzer (OVNA) with improved accuracy based on polarization modulation and stimulated Brillouin scattering (SBS) assisted polarization pulling. The beating between adjacent higher-order optical sidebands which are generated because of the nonlinearity of an electro-optic modulator (EOM) introduces considerable error to the OVNA. In our scheme, the measurement error is significantly reduced by removing the even-order optical sidebands using polarization discrimination. The proposed approach is theoretically analyzed and experimentally verified. The experimental results show that the accuracy of the OVNA is greatly improved compared to a conventional OVNA.

  1. Modeling of the shape of infrared stimulated luminescence signals in feldspars

    DEFF Research Database (Denmark)

    Pagonis, Vasilis; Jain, Mayank; Murray, Andrew S.

    2012-01-01

    This paper presents a new empirical model describing infrared (IR) stimulation phenomena in feldspars. In the model electrons from the ground state of an electron trap are raised by infrared optical stimulation to the excited state, and subsequently recombine with a nearest-neighbor hole via...... a tunneling process, leading to the emission of light. The model explains the experimentally observed existence of two distinct time intervals in the luminescence intensity; a rapid initial decay of the signal followed by a much slower gradual decay of the signal with time.The initial fast decay region...... corresponds to a fast rate of recombination processes taking place along the infrared stimulated luminescence (IRSL) curves. The subsequent decay of the simulated IRSL signal is characterized by a much slower recombination rate, which can be described by a power-law type of equation.Several simulations...

  2. Fluorescence microscopy with diffraction resolution barrier broken by stimulated emission.

    Science.gov (United States)

    Klar, T A; Jakobs, S; Dyba, M; Egner, A; Hell, S W

    2000-07-18

    The diffraction barrier responsible for a finite focal spot size and limited resolution in far-field fluorescence microscopy has been fundamentally broken. This is accomplished by quenching excited organic molecules at the rim of the focal spot through stimulated emission. Along the optic axis, the spot size was reduced by up to 6 times beyond the diffraction barrier. The simultaneous 2-fold improvement in the radial direction rendered a nearly spherical fluorescence spot with a diameter of 90-110 nm. The spot volume of down to 0.67 attoliters is 18 times smaller than that of confocal microscopy, thus making our results also relevant to three-dimensional photochemistry and single molecule spectroscopy. Images of live cells reveal greater details.

  3. Dental caries imaging using hyperspectral stimulated Raman scattering microscopy

    Science.gov (United States)

    Wang, Zi; Zheng, Wei; Jian, Lin; Huang, Zhiwei

    2016-03-01

    We report the development of a polarization-resolved hyperspectral stimulated Raman scattering (SRS) imaging technique based on a picosecond (ps) laser-pumped optical parametric oscillator system for label-free imaging of dental caries. In our imaging system, hyperspectral SRS images (512×512 pixels) in both fingerprint region (800-1800 cm-1) and high-wavenumber region (2800-3600 cm-1) are acquired in minutes by scanning the wavelength of OPO output, which is a thousand times faster than conventional confocal micro Raman imaging. SRS spectra variations from normal enamel to caries obtained from the hyperspectral SRS images show the loss of phosphate and carbonate in the carious region. While polarization-resolved SRS images at 959 cm-1 demonstrate that the caries has higher depolarization ratio. Our results demonstrate that the polarization resolved-hyperspectral SRS imaging technique developed allows for rapid identification of the biochemical and structural changes of dental caries.

  4. Stimulated Brillouin scattering materials, experimental design and applications: A review

    Science.gov (United States)

    Bai, Zhenxu; Yuan, Hang; Liu, Zhaohong; Xu, Pengbai; Gao, Qilin; Williams, Robert J.; Kitzler, Ondrej; Mildren, Richard P.; Wang, Yulei; Lu, Zhiwei

    2018-01-01

    Stimulated Brillouin scattering (SBS), as one type of third-order nonlinear optics effect, is extensively exploited and rapidly developed in the field of lasers and optoelectronics. A large number of theoretical and experimental studies on SBS have been carried out in the past decades. Especially, the exploration of new SBS materials and new types of SBS modulation methods have been engaged simultaneously, as the properties of different materials have great influence on the SBS performance such as generation threshold, Brillouin amplification efficiency, frequency shift, breakdown threshold, etc. This article provides a comprehensive review of the characteristics of different types of SBS materials, SBS applications, experimental design methods, as well as the parameter optimization method, which is expected to provide reference and guidance to SBS related experiments.

  5. Optical dating of the hydroponic farm at Korea

    International Nuclear Information System (INIS)

    Hong, D.G.; Galloway, R.B.; Kim, M.J.; Park, S.B.

    2003-01-01

    For age determination, the single aliquot regenerative-dose (SAR) method was applied to quartz from archaeological materials, using luminescence stimulated by blue light. The quartz samples were extracted from sediment from the hydroponic farm related to rice cultivation in an area of archaeological interest in Buyeo, south of Seoul. The optically stimulated luminescence (OSL) dates obtained offered good agreement with the ages derived by typological assessment and 14 C ages. These ages should contribute significantly to interpretation of the history of rice cultivation in Korea. (author)

  6. Improved Selectivity From a Wavelength Addressable Device for Wireless Stimulation of Neural Tissue

    Directory of Open Access Journals (Sweden)

    Elif Ç. Seymour

    2014-02-01

    Full Text Available Electrical neural stimulation with micro electrodes is a promising technique for restoring lost functions in the central nervous system as a result of injury or disease. One of the problems related to current neural stimulators is the tissue response due to the connecting wires and the presence of a rigid electrode inside soft neural tissue. We have developed a novel, optically activated, microscale photovoltaic neurostimulator based on a custom layered compound semiconductor heterostructure that is both wireless and has a comparatively small volume. Optical activation provides a wireless means of energy transfer to the neurostimulator, eliminating wires and the associated complications. This neurostimulator was shown to evoke action potentials and a functional motor response in the rat spinal cord. In this work, we extend our design to include wavelength selectivity and thus allowing independent activation of devices. As a proof of concept, we fabricated two different microscale devices with different spectral responsivities in the near-infrared region. We assessed the improved addressability of individual devices via wavelength selectivity as compared to spatial selectivity alone through on-bench optical measurements of the devices in combination with an in vivo light intensity profile in the rat cortex obtained in a previous study. We show that wavelength selectivity improves the individual addressability of the floating stimulators, thus increasing the number of devices that can be implanted in close proximity to each other.

  7. Population response characteristics of intrinsic signals in the cat somatosensory cortex following canine mechanical stimulation.

    Science.gov (United States)

    Tao, Jianxiang; Wang, Jian; Li, Zhong; Meng, Jianjun; Yu, Hongbo

    2016-08-04

    Intrinsic signal optical imaging has been widely used to measure functional maps in various sensory cortices due to better spatial resolution and sensitivity for detecting cortical neuroplasticity. However, application of this technique in dentistry has not been reported. In this study, intrinsic signal optical imaging was used to investigate mechanically driven responses in the cat somatosensory cortex, when punctate mechanical stimuli were applied to maxillary canines. The global signal and its spatial organization pattern were obtained. Global signal strength gradually increased with stimulus strength. There was no significant difference in response strength between contralateral and ipsilateral mechanical stimulation. A slightly greater response was recorded in the sigmoidal gyrus than in the coronal gyrus. The cat somatosensory cortex activated by sensory inputs from mechanical stimulation of canines lacks both topographical and functional organization. It is not organized into columns that represent sensory input from each tooth or direction of stimulation. These results demonstrate that intrinsic signal optical imaging is a valid tool for investigating neural responses and neuroplasticity in the somatosensory cortex that represents teeth. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Advances in integrated optics

    CERN Document Server

    Chester, A; Bertolotti, M

    1994-01-01

    This volwne contains the Proceedings of a two-week summer conference titled "Advances in Integrated Optics" held June 1-9, 1993, in Erice, Sicily. This was the 18th annual course organized by the International School of Quantum Electronics, under the auspices of the "Ettore Majorana" Centre for Scientific Culture. The term Integrated Optics signifies guided-wave optical circuits consisting of two or more devices on a single substrate. Since its inception in the late 1960's, Integrated Optics has evolved from a specialized research topic into a broad field of work, ranging from basic research through commercial applications. Today many devices are available on market while a big effort is devolved to research on integrated nonlinear optical devices. This conference was organized to provide a comprehensive survey of the frontiers of this technology, including fundamental concepts, nonlinear optical materials, devices both in the linear and nonlinear regimes, and selected applications. These Proceedings update a...

  9. Silicon Optical Modulator Simulation

    Directory of Open Access Journals (Sweden)

    Soon Thor LIM

    2015-04-01

    Full Text Available We developed a way of predicting and analyzing high speed optical modulator. Our research adopted a bottom-up approach to consider high-speed optical links using an eye diagram. Our method leverages on modular mapping of electrical characteristics to optical characteristics, while attaining the required accuracy necessary for device footprint approaching sub-micron scales where electrical data distribution varies drastically. We calculate for the bias dependent phase shift (2pi/mm and loss (dB/mm for the optical modulator based on the real and imaginary part of complex effective indices. Subsequently, combine effectively both the electrical and optical profiles to construct the optical eye diagram which is the essential gist of signal integrity of such devices.

  10. Fundamentals of optical waveguides

    CERN Document Server

    Okamoto, Katsunari

    2006-01-01

    Fundamentals of Optical Waveguides is an essential resource for any researcher, professional or student involved in optics and communications engineering. Any reader interested in designing or actively working with optical devices must have a firm grasp of the principles of lightwave propagation. Katsunari Okamoto has presented this difficult technology clearly and concisely with several illustrations and equations. Optical theory encompassed in this reference includes coupled mode theory, nonlinear optical effects, finite element method, beam propagation method, staircase concatenation method, along with several central theorems and formulas. Since the publication of the well-received first edition of this book, planar lightwave circuits and photonic crystal fibers have fully matured. With this second edition the advances of these fibers along with other improvements on existing optical technologies are completely detailed. This comprehensive volume enables readers to fully analyze, design and simulate opti...

  11. Lasers and optical engineering

    CERN Document Server

    Das, P

    1991-01-01

    A textbook on lasers and optical engineering should include all aspects of lasers and optics; however, this is a large undertaking. The objective of this book is to give an introduction to the subject on a level such that under­ graduate students (mostly juniors/seniors), from disciplines like electrical engineering, physics, and optical engineering, can use the book. To achieve this goal, a lot of basic background material, central to the subject, has been covered in optics and laser physics. Students with an elementary knowledge of freshman physics and with no formal courses in electromagnetic theory should be able to follow the book, although for some sections, knowledge of electromagnetic theory, the Fourier transform, and linear systems would be highly beneficial. There are excellent books on optics, laser physics, and optical engineering. Actually, most of my knowledge was acquired through these. However, when I started teaching an undergraduate course in 1974, under the same heading as the title of th...

  12. Tunable micro-optics

    CERN Document Server

    Duppé, Claudia

    2015-01-01

    Presenting state-of-the-art research into the dynamic field of tunable micro-optics, this is the first book to provide a comprehensive survey covering a varied range of topics including novel materials, actuation concepts and new imaging systems in optics. Internationally renowned researchers present a diverse range of chapters on cutting-edge materials, devices and subsystems, including soft matter, artificial muscles, tunable lenses and apertures, photonic crystals, and complete tunable imagers. Special contributions also provide in-depth treatment of micro-optical characterisation, scanners, and the use of natural eye models as inspiration for new concepts in advanced optics. With applications extending from medical diagnosis to fibre telecommunications, Tunable Micro-optics equips readers with a solid understanding of the broader technical context through its interdisciplinary approach to the realisation of new types of optical systems. This is an essential resource for engineers in industry and academia,...

  13. Ultraviolet Stimulated Emission from Sol-Gel Spin Coated ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Ahmed S. Razeen

    2017-01-01

    Full Text Available Low cost ultraviolet stimulated emission has been generated using optical excitation of ZnO thin films deposited by sol-gel spin coating on n+ As-doped 100 Si-substrate. The number of deposited layers and the heat treatment have been investigated to obtain a film that can generate stimulated emission under optical excitation. The optimum condition for preparation of the film has been presented. X-ray diffraction and scanning electron microscope have been used for structural and morphological investigations. Input-output intensity dependence and spectral width, peak emission wavelength, and the quantum efficiency versus the pump intensity have been presented. A quantum efficiency of about 24.2% has been reported, a power exponent higher than 8 has been obtained in input-output intensity dependence, and a threshold of about 23 Mw/cm2 has been evaluated for the samples. The mechanism by which stimulated emission occurs has been discussed. The results show that sol-gel spin coating is a promising method for generating ultraviolet stimulated emission from ZnO thin films.

  14. Current density in radiation stimulated superconductors

    International Nuclear Information System (INIS)

    Wafelbakker, C.K.

    1977-01-01

    Eliashberg's theory of stimulated superconductivity is reviewed and discussed within the BCS-Mattis formalism for impure superconductors. Stimulation by microwaves as well as by acoustical fields is considered. Eliashberg's results are completed by obtaining the nonequilibrium current response to an applied transverse vector potential. The resulting expression may be used to obtain the critical current of small specimens. (Auth.)

  15. Are Prescription Stimulants “Smart Pills”?

    Science.gov (United States)

    Smith, M. Elizabeth; Farah, Martha J.

    2013-01-01

    Use of prescription stimulants by normal healthy individuals to enhance cognition is said to be on the rise. Who is using these medications for cognitive enhancement, and how prevalent is this practice? Do prescription stimulants in fact enhance cognition for normal healthy people? We review the epidemiological and cognitive neuroscience literatures in search of answers to these questions. Epidemiological issues addressed include the prevalence of nonmedical stimulant use, user demographics, methods by which users obtain prescription stimulants, and motivations for use. Cognitive neuroscience issues addressed include the effects of prescription stimulants on learning and executive function, as well as the task and individual variables associated with these effects. Little is known about the prevalence of prescription stimulant use for cognitive enhancement outside of student populations. Among college students, estimates of use vary widely but, taken together, suggest that the practice is commonplace. The cognitive effects of stimulants on normal healthy people cannot yet be characterized definitively, despite the volume of research that has been carried out on these issues. Published evidence suggests that declarative memory can be improved by stimulants, with some evidence consistent with enhanced consolidation of memories. Effects on the executive functions of working memory and cognitive control are less reliable but have been found for at least some individuals on some tasks. In closing, we enumerate the many outstanding questions that remain to be addressed by future research and also identify obstacles facing this research. PMID:21859174

  16. Swelling of rat hepatocytes stimulates glycogen synthesis

    NARCIS (Netherlands)

    Baquet, A.; Hue, L.; Meijer, A. J.; van Woerkom, G. M.; Plomp, P. J.

    1990-01-01

    In hepatocytes from fasted rats, several amino acids are known to stimulate glycogen synthesis via activation of glycogen synthase. The hypothesis that an increase in cell volume resulting from amino acid uptake may be involved in the stimulation of glycogen synthesis is supported by the following

  17. Thyroid stimulating hormone and subclinical thyroid dysfunction

    International Nuclear Information System (INIS)

    Guo Yongtie

    2008-01-01

    Subclinical thyroid dysfunction has mild clinical symptoms. It is nonspecific and not so noticeable. It performs only for thyroid stimulating hormone rise and decline. The value of early diagnosis and treatment of thyroid stimulating hormone in subclinical thyroid dysfunction were reviewed. (authors)

  18. Stimulation of seeds by low dose irradiation

    International Nuclear Information System (INIS)

    Lawson, Helen

    1976-05-01

    The first section of the bibliography lists materials on the stimulation of seeds by low dose irradiation, with particular reference to stimulation of germination and yield. The second section contains a small number of selected references on seed irradiation facilities. (author)

  19. Inhibition of Lipopolysaccharide-Stimulated Neuro- Inflammatory ...

    African Journals Online (AJOL)

    Purpose: To investigate the in vitro antioxidant and anti-neuroinflammatory effects of Tetragonia tetragonoides (Pall.) Kuntze extract (TKE) in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Methods: To evaluate the effects of TKE, LPS-stimulated BV microglia were used and the expression and production of ...

  20. Anal sphincter responses after perianal electrical stimulation

    DEFF Research Database (Denmark)

    Pedersen, Ejnar; Klemar, B; Schrøder, H D

    1982-01-01

    not fatigued by repeated stimulation, were most dependent on placement of stimulating and recording electrodes, and always had a higher threshold than the third response. The third response was constantly present in normal subjects. It had the longest EMG response and the latency decreased with increasing...