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Sample records for shorter wavelength relative

  1. Do shorter wavelengths improve contrast in optical mammography?

    International Nuclear Information System (INIS)

    Taroni, P; Pifferi, A; Torricelli, A; Spinelli, L; Danesini, G M; Cubeddu, R

    2004-01-01

    The detection of tumours with time-resolved transmittance imaging relies essentially on blood absorption. Previous theoretical and phantom studies have shown that both contrast and spatial resolution of optical images are affected by the optical properties of the background medium, and high absorption and scattering are generally beneficial. Based on these observations, wavelengths shorter than presently used (680-780 nm) could be profitable for optical mammography. A study was thus performed analysing time-resolved transmittance images at 637, 656, 683 and 785 nm obtained from 26 patients bearing 16 tumours and 15 cysts. The optical contrast proved to increase upon decreasing wavelengths for the detection of cancers in late-gated intensity images, with higher gain in contrast for lesions of smaller size (<1.5 cm diameter). For cysts either a progressive increase or decrease in contrast with wavelength was observed in scattering images

  2. Extending 3D near-cloud corrections from shorter to longer wavelengths

    International Nuclear Information System (INIS)

    Marshak, Alexander; Evans, K. Frank; Várnai, Tamás; Wen, Guoyong

    2014-01-01

    Satellite observations have shown a positive correlation between cloud amount and aerosol optical thickness (AOT) that can be explained by the humidification of aerosols near clouds, and/or by cloud contamination by sub-pixel size clouds and the cloud adjacency effect. The last effect may substantially increase reflected radiation in cloud-free columns, leading to overestimates in the retrieved AOT. For clear-sky areas near boundary layer clouds the main contribution to the enhancement of clear sky reflectance at shorter wavelengths comes from the radiation scattered into clear areas by clouds and then scattered to the sensor by air molecules. Because of the wavelength dependence of air molecule scattering, this process leads to a larger reflectance increase at shorter wavelengths, and can be corrected using a simple two-layer model [18]. However, correcting only for molecular scattering skews spectral properties of the retrieved AOT. Kassianov and Ovtchinnikov [9] proposed a technique that uses spectral reflectance ratios to retrieve AOT in the vicinity of clouds; they assumed that the cloud adjacency effect influences the spectral ratio between reflectances at two wavelengths less than it influences the reflectances themselves. This paper combines the two approaches: It assumes that the 3D correction for the shortest wavelength is known with some uncertainties, and then it estimates the 3D correction for longer wavelengths using a modified ratio method. The new approach is tested with 3D radiances simulated for 26 cumulus fields from Large-Eddy Simulations, supplemented with 40 aerosol profiles. The results showed that (i) for a variety of cumulus cloud scenes and aerosol profiles over ocean the 3D correction due to cloud adjacency effect can be extended from shorter to longer wavelengths and (ii) the 3D corrections for longer wavelengths are not very sensitive to unbiased random uncertainties in the 3D corrections at shorter wavelengths. - Highlights:

  3. Towards shorter wavelength x-ray lasers using a high power, short pulse pump laser

    International Nuclear Information System (INIS)

    Tighe, W.; Krushelnick, K.; Valeo, E.; Suckewer, S.

    1991-05-01

    A near-terawatt, KrF* laser system, focussable to power densities >10 18 W/cm 2 has been constructed for use as a pump laser in various schemes aimed at the development of x-ray lasing below 5nm. The laser system along with output characteristics such as the pulse duration, the focal spot size, and the percentage of amplified spontaneous emission (ASE) emitted along with the laser pulse will be presented. Schemes intended to lead to shorter wavelength x-ray emission will be described. The resultant requirements on the pump laser characteristics and the target design will be outlined. Results from recent solid target experiments and two-laser experiments, showing the interaction of a high-power, short pulse laser with a preformed plasma, will be presented. 13 refs., 5 figs

  4. Psoralen-mediated virus photoinactivation in platelet concentrates: enhanced specificity of virus kill in the absence of shorter UVA wavelengths

    International Nuclear Information System (INIS)

    Margolis-Nunno, Henrietta; Robinson, Richard; Horowitz, Bernard; Ben-Hur, Ehud; Geacintov, N.E.

    1995-01-01

    Treatments with psoralens and long-wavelength ultraviolet radiation (UVA, 320-400 nm; PUVA) have shown efficacy for virus sterilization of platelet concentrates (PC). We have employed the psoralen derivative 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT), and have found that platelet integrity is best preserved when rutin, a flavonoid that quenches multiple reactive oxygen species, is present during AMT/UVA treatment of PC. In this report, we examine the effects of different UVA spectra under our standard PC treatment conditions (i.e. 50 μg/mL AMT, 0.35 mM rutin and 38 J/cm 2 UVA). Added vesicular stomatitis virus (VSV; ≥ 5.5 log 10 ) was completely inactivated with the simultaneous maintenance of the platelet aggregation response (> 90% of control) when a UVA light source with transmission mainly between 360 and 370 nm (narrow UVA1) was used. In contrast, with a broad-band UVA (320-400 nm; broad UVA) light source, the aggregation response was greatly compromised (< 50% of control) with only a minor increase in the rate of VSV kill. With this lamp, platelet function could be improved to about 75% of the control by adding a long-pass filter, which reduced the transmission of shorter (≤ 345 nm) UVA wavelengths (340-400 nm; UVA1). At equivalent levels of virus kill, aggregation function was always best preserved when narrow UVA1 was used for PUVA treatment. Even in the absence of AMT, and with or without rutin present, narrow UVA1 irradiation was better tolerated by platelets than was broad UVA. (author)

  5. Plasma shifts of C VI Lyman lines to shorter wavelengths. Final report, November 4, 1981-September 30, 1983

    International Nuclear Information System (INIS)

    Griem, H.R.

    1984-07-01

    The first two years of this ongoing research program were devoted to experimental observations of shifts and widths of hydrogenic ion lines emitted by very dense plasmas. This search is an essential step in the general study of the properties of bound states of multiply charged ions in dense plasmas. This research is of importance in a number of areas, notably equilibrium statistical mechanics (equation of state), plasma radiation physics (energy transport and diagnostics) and calibration of wavelengths in the extreme vacuum uv region (10 A < lambda < 200 A). In the latter case, the wavelengths of lines from one-electron ions are generally accepted to be well known theoretically and are considered as standards for plate calibration. The question nevertheless arises whether or not significant changes in wavelength can occur, e.g., in low-inductance sparks or laser produced plasma which are often used as line sources

  6. Shorter height is related to lower cardiovascular disease risk – A narrative review

    Directory of Open Access Journals (Sweden)

    Thomas T. Samaras

    2013-01-01

    Full Text Available Numerous Western studies have shown a negative correlation between height and cardiovascular disease. However, these correlations do not prove causation. This review provides a variety of studies showing short people have little to no cardiovascular disease. When shorter people are compared to taller people, a number of biological mechanisms evolve favoring shorter people, including reduced telomere shortening, lower atrial fibrillation, higher heart pumping efficiency, lower DNA damage, lower risk of blood clots, lower left ventricular hypertrophy and superior blood parameters. The causes of increased heart disease among shorter people in the developed world are related to lower income, excessive weight, poor diet, lifestyle factors, catch-up growth, childhood illness and poor environmental conditions. For short people in developed countries, the data indicate that a plant-based diet, leanness and regular exercise can substantially reduce the risk of cardiovascular disease.

  7. Highly efficient pulsed power supply system with a two-stage LC generator and a step-up transformer for fast capillary discharge soft x-ray laser at shorter wavelength

    International Nuclear Information System (INIS)

    Sakai, Yusuke; Takahashi, Shnsuke; Komatsu, Takanori; Song, Inho; Watanabe, Masato; Hotta, Eiki

    2010-01-01

    Highly efficient and compact pulsed power supply system for a capillary discharge soft x-ray laser (SXRL) has been developed. The system consists of a 2.2 μF two-stage LC inversion generator, a 2:54 step-up transformer, a 3 nF water capacitor, and a discharge section with a few tens of centimeter length capillary. Adoption of the pulsed transformer in combination with the LC inversion generator enables us to use only one gap switch in the circuit for charging the water capacitor up to about 0.5 MV. Furthermore, step-up ratio of a water capacitor voltage to a LC inversion generator initial charging voltage is about 40 with energy transfer efficiency of about 50%. It also leads to good reproducibility of a capillary discharge which is necessary for lasing a SXRL stably. For the study of the possibility of lasing a SXRL at shorter wavelength in a small laboratory scale, high-density and high-temperature plasma column suitable for the laser can be generated relatively easily with this system.

  8. Shorter Versus Longer Shift Durations to Mitigate Fatigue and Fatigue-Related Risks in Emergency Medical Services Personnel and Related Shift Workers: A Systematic Review

    Science.gov (United States)

    2018-01-11

    Background: This study comprehensively reviewed the literature on the impact of shorter versus longer shifts on critical and important outcomes for Emergency Medical Services (EMS) personnel and related shift worker groups. Methods: Six databases (e....

  9. Shorter Leukocyte Telomere Length in Relation to Presumed Nonalcoholic Fatty Liver Disease in Mexican-American Men in NHANES 1999–2002

    Directory of Open Access Journals (Sweden)

    Janet M. Wojcicki

    2017-01-01

    Full Text Available Leukocyte telomere length is shorter in response to chronic disease processes associated with inflammation such as diabetes mellitus and coronary artery disease. Data from the National Health and Nutrition Examination Survey (NHANES from 1999 to 2002 was used to explore the relationship between leukocyte telomere length and presumed NAFLD, as indicated by elevated serum alanine aminotransferase (ALT levels, obesity, or abdominal obesity. Logistic regression models were used to evaluate the relationship between telomere length and presumed markers of NAFLD adjusting for possible confounders. There was no relationship between elevated ALT levels, abdominal obesity, or obesity and telomere length in adjusted models in NHANES (OR 1.13, 95% CI 0.48–2.65; OR 1.17, 95% CI 0.52–2.62, resp.. Mexican-American men had shorter telomere length in relation to presumed NAFLD (OR 0.07, 95% CI 0.006–0.79 and using different indicators of NAFLD (OR 0.012, 95% CI 0.0006–0.24. Mexican origin with presumed NAFLD had shorter telomere length than men in other population groups. Longitudinal studies are necessary to evaluate the role of telomere length as a potential predictor to assess pathogenesis of NALFD in Mexicans.

  10. Driving for shorter outages

    International Nuclear Information System (INIS)

    Tritch, S.

    1996-01-01

    Nuclear plant outages are necessary to complete activities that cannot be completed during the operating cycle, such as steam generator inspection and testing, refueling, installing modifications, and performing maintenance tests. The time devoted to performing outages is normally the largest contributor to plant unavailability. Similarly, outage costs are a sizable portion of the total plant budget. The scope and quality of work done during outages directly affects operating reliability and the number of unplanned outages. Improved management and planning of outages enhances the margin of safety during the outage and results in increased plant reliability. The detailed planning and in-depth preparation that has become a necessity for driving shorter outage durations has also produced safer outages and improved post-outage reliability. Short outages require both plant and vendor management to focus on all aspects of the outage. Short outage durations, such as 26 days at South Texas or 29 days at North Anna, require power plant inter-department and intra-department teamwork and communication and vendor participation. In this paper shorter and safer outage at the 3-loop plants in the United States are explained. (J.P.N.)

  11. Disparate patterns of age-related changes in lipid peroxidation in long-lived naked mole-rats and shorter-lived mice.

    Science.gov (United States)

    Andziak, Blazej; Buffenstein, Rochelle

    2006-12-01

    A key tenet of the oxidative stress theory of aging is that levels of accrued oxidative damage increase with age. Differences in damage generation and accumulation therefore may underlie the natural variation in species longevity. We compared age-related profiles of whole-organism lipid peroxidation (urinary isoprostanes) and liver lipid damage (malondialdehyde) in long living naked mole-rats [maximum lifespan (MLS) > 28.3 years] and shorter-living CB6F1 hybrid mice (MLS approximately 3.5 years). In addition, we compared age-associated changes in liver non-heme iron to assess how intracellular conditions, which may modulate oxidative processes, are affected by aging. Surprisingly, even at a young age, concentrations of both markers of lipid peroxidation, as well as of iron, were at least twofold (P naked mole tats than in mice. This refutes the hypothesis that prolonged naked mole-rat longevity is due to superior protection against oxidative stress. The age-related profiles of all three parameters were distinctly species specific. Rates of lipid damage generation in mice were maintained throughout adulthood, while accrued damage in old animals was twice that of young mice. In naked mole-rats, urinary isoprostane excretion declined by half with age (P naked mole-rats is independent of oxidative stress parameters.

  12. Wavelength conversion devices

    DEFF Research Database (Denmark)

    Mikkelsen, Benny; Durhuus, Terji; Jørgensen, Carsten

    1996-01-01

    system requirements. The ideal wavelength converter should be transparent to the bit rate and signal format and provide an unchirped output signal with both a high extinction ratio and a large signal-to-noise ratio. It should allow conversion to both shorter and longer wavelengths with equal performance...

  13. Absorption spectrum of DNA for wavelengths greater than 300 nm

    International Nuclear Information System (INIS)

    Sutherland, J.C.; Griffin, K.P.

    1981-01-01

    Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths

  14. Isolating long-wavelength fluctuation from structural relaxation in two-dimensional glass: cage-relative displacement

    Science.gov (United States)

    Shiba, Hayato; Keim, Peter; Kawasaki, Takeshi

    2018-03-01

    It has recently been revealed that long-wavelength fluctuation exists in two-dimensional (2D) glassy systems, having the same origin as that given by the Mermin-Wagner theorem for 2D crystalline solids. In this paper, we discuss how to characterise quantitatively the long-wavelength fluctuation in a molecular dynamics simulation of a lightly supercooled liquid. We employ the cage-relative mean-square displacement (MSD), defined on relative displacement to its cage, to quantitatively separate the long-wavelength fluctuation from the original MSD. For increasing system size the amplitude of acoustic long wavelength fluctuations not only increases but shifts to later times causing a crossover with structural relaxation of caging particles. We further analyse the dynamic correlation length using the cage-relative quantities. It grows as the structural relaxation becomes slower with decreasing temperature, uncovering an overestimation by the four-point correlation function due to the long-wavelength fluctuation. These findings motivate the usage of cage-relative MSD as a starting point for analysis of 2D glassy dynamics.

  15. Short wavelength FELS

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs

  16. Short wavelength FELS

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

  17. A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

    Directory of Open Access Journals (Sweden)

    M. I. Cotterell

    2017-08-01

    Full Text Available Calculations of aerosol radiative forcing require knowledge of wavelength-dependent aerosol optical properties, such as single-scattering albedo. These aerosol optical properties can be calculated using Mie theory from knowledge of the key microphysical properties of particle size and refractive index, assuming that atmospheric particles are well-approximated to be spherical and homogeneous. We provide refractive index determinations for aqueous aerosol particles containing the key atmospherically relevant inorganic solutes of NaCl, NaNO3, (NH42SO4, NH4HSO4 and Na2SO4, reporting the refractive index variation with both wavelength (400–650 nm and relative humidity (from 100 % to the efflorescence value of the salt. The accurate and precise retrieval of refractive index is performed using single-particle cavity ring-down spectroscopy. This approach involves probing a single aerosol particle confined in a Bessel laser beam optical trap through a combination of extinction measurements using cavity ring-down spectroscopy and elastic light-scattering measurements. Further, we assess the accuracy of these refractive index measurements, comparing our data with previously reported data sets from different measurement techniques but at a single wavelength. Finally, we provide a Cauchy dispersion model that parameterises refractive index measurements in terms of both wavelength and relative humidity. Our parameterisations should provide useful information to researchers requiring an accurate and comprehensive treatment of the wavelength and relative humidity dependence of refractive index for the inorganic component of atmospheric aerosol.

  18. Refractive indices of human skin tissues at eight wavelengths and estimated dispersion relations between 300 and 1600 nm

    International Nuclear Information System (INIS)

    Ding Huafeng; Lu, Jun Q; Wooden, William A; Kragel, Peter J; Hu Xinhua

    2006-01-01

    The refractive index of human skin tissues is an important parameter in characterizing the optical response of the skin. We extended a previously developed method of coherent reflectance curve measurement to determine the in vitro values of the complex refractive indices of epidermal and dermal tissues from fresh human skin samples at eight wavelengths between 325 and 1557 nm. Based on these results, dispersion relations of the real refractive index have been obtained and compared in the same spectral region

  19. In situ aerosol characterization at Cape Verde. Part 2: Parametrization of relative humidity- and wavelength-dependent aerosol optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Schladitz, Alexander; Muller, Thomas; Nordmann, Stephan; Tesche, Matthias; Wiedensohler, Alfred (Leibniz Institute for Tropospheric Research (IfT), Leipzig (Germany)), e-mail: alexander.schladitz@tropos.de; Gross, Silke; Freudenthaler, Volker; Gasteiger, Josef (Meteorological Institute, Ludwig-Maximilians-Universitaet, Munich (Germany))

    2011-09-15

    An observation-based numerical study of humidity-dependent aerosol optical properties of mixed marine and Saharan mineral dust aerosol is presented. An aerosol model was developed based on measured optical and microphysical properties to describe the marine and Saharan dust aerosol at Cape Verde. A wavelength-dependent optical equivalent imaginary part of the refractive index and a scattering non-sphericity factor for Saharan dust were derived. Simulations of humidity effects on optical properties by the aerosol model were validated with relative measurements of the extinction coefficient at ambient conditions. Parametrizations were derived to describe the humidity dependence of the extinction, scattering, and absorption coefficients as well as the asymmetry parameter and single scattering albedo. For wavelengths (300-950 nm) and dry dust volume fractions (0-1), aerosol optical properties as a function of relative humidity (RH = 0-90%) can be calculated from tabulated parameters. For instance, at a wavelength of 550 nm, a volume fraction of 0.5 of dust on the total particle volume (dry conditions) and a RH of 90%, the enhancements for the scattering, extinction and absorption coefficients are 2.55, 2.46 and 1.04, respectively, while the enhancements for the asymmetry parameter and single scattering albedo are 1.11 and 1.04

  20. The Napoleon Complex: When Shorter Men Take More.

    Science.gov (United States)

    Knapen, Jill E P; Blaker, Nancy M; Van Vugt, Mark

    2018-05-01

    Inspired by an evolutionary psychological perspective on the Napoleon complex, we hypothesized that shorter males are more likely to show indirect aggression in resource competitions with taller males. Three studies provide support for our interpretation of the Napoleon complex. Our pilot study shows that men (but not women) keep more resources for themselves when they feel small. When paired with a taller male opponent (Study 1), shorter men keep more resources to themselves in a game in which they have all the power (dictator game) versus a game in which the opponent also has some power (ultimatum game). Furthermore, shorter men are not more likely to show direct, physical aggression toward a taller opponent (Study 2). As predicted by the Napoleon complex, we conclude that (relatively) shorter men show greater behavioral flexibility in securing resources when presented with cues that they are physically less competitive. Theoretical and practical implications are discussed.

  1. Wavelength scaling of laser plasma coupling

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1983-01-01

    The use of shorter wavelength laser light both enhances collisional absorption and reduces deleterious collective plasma effects. Coupling processes which can be important in reactor-size targets are briefly reviewed. Simple estimates are presented for the intensity-wavelength regime in which collisional absorption is high and collective effects are minimized

  2. Towards short wavelengths FELs workshop

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Winick, H.

    1993-01-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program

  3. Towards short wavelengths FELs workshop

    Science.gov (United States)

    Ben-Zvi, I.; Winick, H.

    1993-11-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FEL's offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FEL's will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

  4. Implications of shorter cells in PEP

    International Nuclear Information System (INIS)

    Wiedemann, H.

    1975-01-01

    Further studies on the beam-stay-clear requirements in PEP led to the conclusion that the vertical aperture needed to be enlarged. There are two main reasons for that: Observations at SPEAR indicate that the aperture should be large enough for a fully coupled beam. Full coupling of the horizontal and vertical betatron oscillations occurs not only occasionally when the energy, tune or betatron function at the interaction point is changed but also due to the beam/endash/beam effect of two strong colliding beams. The second reason for an increased aperture requirement is the nonlinear perturbation of the particle trajectories by the sextupoles. This perturbation increases a fully coupled beam by another 50% to 80%. Both effects together with a +-5 mm allowance for closed orbit perturbation result in a vertical beam-stay-clear in the bending magnets of +-4.8 to +-5.6 cm, compared to the present +-2.0 cm. This beam-stay-clear, together with additional space for vacuum chamber, etc., leads to very costly bending magnets. In this note, a shorter cell length is proposed which would reduce considerably the vertical beam-stay-clear requirements in the bending magnets. 7 figs

  5. Wavelength dispersive X-ray fluorescence analysis using fundamental parameter approach of Catha edulis and other related plant samples

    Energy Technology Data Exchange (ETDEWEB)

    Shaltout, Abdallah A., E-mail: shaltout_a@hotmail.com [Spectroscopy Department, Physics Division, National Research Center, El Behooth Str., 12622 Dokki, Cairo (Egypt); Faculty of science, Taif University, 21974 Taif, P.O. Box 888 (Saudi Arabia); Moharram, Mohammed A. [Spectroscopy Department, Physics Division, National Research Center, El Behooth Str., 12622 Dokki, Cairo (Egypt); Mostafa, Nasser Y. [Faculty of science, Taif University, 21974 Taif, P.O. Box 888 (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia (Egypt)

    2012-01-15

    This work is the first attempt to quantify trace elements in the Catha edulis plant (Khat) with a fundamental parameter approach. C. edulis is a famous drug plant in east Africa and Arabian Peninsula. We have previously confirmed that hydroxyapatite represents one of the main inorganic compounds in the leaves and stalks of C. edulis. Comparable plant leaves from basil, mint and green tea were included in the present investigation as well as trifolium leaves were included as a non-related plant. The elemental analyses of the plants were done by Wavelength Dispersive X-Ray Fluorescence (WDXRF) spectroscopy. Standard-less quantitative WDXRF analysis was carried out based on the fundamental parameter approaches. According to the standard-less analysis algorithms, there is an essential need for an accurate determination of the amount of organic material in the sample. A new approach, based on the differential thermal analysis, was successfully used for the organic material determination. The obtained results based on this approach were in a good agreement with the commonly used methods. Depending on the developed method, quantitative analysis results of eighteen elements including; Al, Br, Ca, Cl, Cu, Fe, K, Na, Ni, Mg, Mn, P, Rb, S, Si, Sr, Ti and Zn were obtained for each plant. The results of the certified reference materials of green tea (NCSZC73014, China National Analysis Center for Iron and Steel, Beijing, China) confirmed the validity of the proposed method. - Highlights: Black-Right-Pointing-Pointer Quantitative analysis of Catha edulis was carried out using standardless WDXRF. Black-Right-Pointing-Pointer Differential thermal analysis was used for determination of the loss of ignition. Black-Right-Pointing-Pointer The existence of hydroxyapatite in Catha edulis plant has been confirmed. Black-Right-Pointing-Pointer The CRM results confirmed the validity of the developed method.

  6. Wavelength dispersive X-ray fluorescence analysis using fundamental parameter approach of Catha edulis and other related plant samples

    International Nuclear Information System (INIS)

    Shaltout, Abdallah A.; Moharram, Mohammed A.; Mostafa, Nasser Y.

    2012-01-01

    This work is the first attempt to quantify trace elements in the Catha edulis plant (Khat) with a fundamental parameter approach. C. edulis is a famous drug plant in east Africa and Arabian Peninsula. We have previously confirmed that hydroxyapatite represents one of the main inorganic compounds in the leaves and stalks of C. edulis. Comparable plant leaves from basil, mint and green tea were included in the present investigation as well as trifolium leaves were included as a non-related plant. The elemental analyses of the plants were done by Wavelength Dispersive X-Ray Fluorescence (WDXRF) spectroscopy. Standard-less quantitative WDXRF analysis was carried out based on the fundamental parameter approaches. According to the standard-less analysis algorithms, there is an essential need for an accurate determination of the amount of organic material in the sample. A new approach, based on the differential thermal analysis, was successfully used for the organic material determination. The obtained results based on this approach were in a good agreement with the commonly used methods. Depending on the developed method, quantitative analysis results of eighteen elements including; Al, Br, Ca, Cl, Cu, Fe, K, Na, Ni, Mg, Mn, P, Rb, S, Si, Sr, Ti and Zn were obtained for each plant. The results of the certified reference materials of green tea (NCSZC73014, China National Analysis Center for Iron and Steel, Beijing, China) confirmed the validity of the proposed method. - Highlights: ► Quantitative analysis of Catha edulis was carried out using standardless WDXRF. ► Differential thermal analysis was used for determination of the loss of ignition. ► The existence of hydroxyapatite in Catha edulis plant has been confirmed. ► The CRM results confirmed the validity of the developed method.

  7. Novel thermal annealing methodology for permanent tuning polymer optical fiber Bragg gratings to longer wavelengths.

    Science.gov (United States)

    Pospori, A; Marques, C A F; Sagias, G; Lamela-Rivera, H; Webb, D J

    2018-01-22

    The Bragg wavelength of a polymer optical fiber Bragg grating can be permanently shifted by utilizing the thermal annealing method. In all the reported fiber annealing cases, the authors were able to tune the Bragg wavelength only to shorter wavelengths, since the polymer fiber shrinks in length during the annealing process. This article demonstrates a novel thermal annealing methodology for permanently tuning polymer optical fiber Bragg gratings to any desirable spectral position, including longer wavelengths. Stretching the polymer optical fiber during the annealing process, the period of Bragg grating, which is directly related with the Bragg wavelength, can become permanently longer. The methodology presented in this article can be used to multiplex polymer optical fiber Bragg gratings at any desirable spectral position utilizing only one phase-mask for their photo-inscription, reducing thus their fabrication cost in an industrial setting.

  8. Short wavelength FELs using the SLAC linac

    International Nuclear Information System (INIS)

    Winick, H.; Bane, K.; Boyce, R.

    1993-08-01

    Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops

  9. 36 CFR 223.81 - Shorter advertising periods in emergencies.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Shorter advertising periods... OF AGRICULTURE SALE AND DISPOSAL OF NATIONAL FOREST SYSTEM TIMBER Timber Sale Contracts Advertisement and Bids § 223.81 Shorter advertising periods in emergencies. In emergency situations where prompt...

  10. The risk of shorter fasting time for pediatric deep sedation.

    Science.gov (United States)

    Clark, Mathew; Birisci, Esma; Anderson, Jordan E; Anliker, Christina M; Bryant, Micheal A; Downs, Craig; Dalabih, Abdallah

    2016-01-01

    Current guidelines adopted by the American Academy of Pediatrics calls for prolonged fasting times before performing pediatric procedural sedation and analgesia (PSA). PSA is increasingly provided to children outside of the operating theater by sedation trained pediatric providers and does not require airway manipulation. We investigated the safety of a shorter fasting time compared to a longer and guideline compliant fasting time. We tried to identify the association between fasting time and sedation-related complications. This is a prospective observational study that included children 2 months to 18 years of age and had an American Society of Anesthesiologists physical status classification of I or II, who underwent deep sedation for elective procedures, performed by pediatric critical care providers. Procedures included radiologic imaging studies, electroencephalograms, auditory brainstem response, echocardiograms, Botox injections, and other minor surgical procedures. Subjects were divided into two groups depending on the length of their fasting time (4-6 h and >6 h). Complication rates were calculated and compared between the three groups. In the studied group of 2487 subjects, 1007 (40.5%) had fasting time of 4-6 h and the remaining 1480 (59.5%) subjects had fasted for >6 h. There were no statistically significant differences in any of the studied complications between the two groups. This study found no difference in complication rate in regard to the fasting time among our subjects cohort, which included only healthy children receiving elective procedures performed by sedation trained pediatric critical care providers. This suggests that using shorter fasting time may be safe for procedures performed outside of the operating theater that does not involve high-risk patients or airway manipulation.

  11. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  12. One long chain among shorter chains : the Flory approach revisited

    OpenAIRE

    Raphaël , E.; Fredrickson , G.; Pincus , P.

    1992-01-01

    We consider the mean square end-to-end distance of a long chain immersed in a monodisperse, concentrated solution of shorter, chemically identical chains. In contrast with the earlier work of Flory, no simplifying assumption on the wave vector dependence of the effective potential between segments is made. In order to obtain a closed form expression for the dimension of the long chain, we first derive a general expression for the mean square end-to-end distance of a flexible chain with arbitr...

  13. Uniting ripple-formation theory under water and winds: A universal scaling relation for the wavelength of fluid-drag ripples across fluids and planetary bodies

    Science.gov (United States)

    Lapotre, M. G. A.; Lamb, M. P.; Ewing, R. C.; McElroy, B. J.

    2016-12-01

    Current ripples form on riverbeds and on the seafloor from viscous drag exerted by water flow over sand and are thought to be absent in subaerial systems, where ripple formation is dominated by a mechanism involving the impacting and splashing of sand grains. A fluid-drag mechanism, however, is not precluded in subaerial conditions and was originally hypothesized by R. A. Bagnold. Despite decades of observations in the field and in the laboratory, no universal scaling relation exists to predict the size of fluid-drag ripples. We combine dimensional analysis and a new extensive data compilation to develop a relationship and predict the equilibrium wavelength of current ripples. Our analysis shows that ripples are spaced farther apart when formed by more viscous fluids, smaller bed shear velocities, in coarser grains, or for smaller sediment specific gravity. Our scaling relation also highlights the abrupt transition between current ripples and subaqueous dunes, and thus allows for a process-based segregation of ripples from dunes. When adjusting for subaerial conditions, we predict the formation of decimeter-scale wind-drag ripples on Earth and meter-scale wind-drag ripples on Mars. The latter are ubiquitous on the Red Planet, and are found to co-exist with smaller decimeter-scale ripples, which we interpret as impact ripples. Because the predicted scale of terrestrial wind-drag ripples overlaps with that of impact ripples, it is possible that wind-drag ripples exist on Earth too, but are not recognized as such. When preserved in rocks, fluid-drag ripple stratification records flow directions and fluid properties that are crucial to constrain paleo-environments. Our new theory allows for predictions of ripple size, perhaps in both fluvial and eolian settings, and thus potentially represents a powerful tool for paleo-environmental reconstructions on different planetary bodies.

  14. Estimates of SASE power in the short wavelength region

    International Nuclear Information System (INIS)

    Kim, Kwang-Je.

    1992-03-01

    Given a sufficiently bright electron beam, the self-amplified-spontaneous emission (SASE) can provide gigawatts of short wavelength coherent radiation. The advantages of SASE approach are that is requires neither optical cavity nor an imput seed laser. In this note, we estimate the peak power performance of SASE for wavelengths shorter than 1000 Angstrom. At each wavelength, we calculate the saturated power from a uniform parameter undulator and the enhanced power from a tapered undulator. The method described here is an adaptation of that discussed by L.H. Yu, who discussed the harmonic generation scheme with seeded laser, to the case of SASE

  15. Effective wavelength calibration for moire fringe projection

    International Nuclear Information System (INIS)

    Purcell, Daryl; Davies, Angela; Farahi, Faramarz

    2006-01-01

    The fringe patterns seen when using moire instruments are similar to the patterns seen in traditional interferometry but differ in the spacing between consecutive fringes. In traditional interferometry, the spacing is constant and related to the wavelength of the source. In moire fringe projection, the spacing (the effective wavelength) may not be constant over the field of view and the spacing depends on the system geometry. In these cases, using a constant effective wavelength over the field of view causes inaccurate surface height measurements. We examine the calibration process of the moirefringe projection measurement, which takes this varying wavelength into account to produce a pixel-by-pixel wavelength map. The wavelength calibration procedure is to move the object in the out-of-plane direction a known distance until every pixel intensity value goes through at least one cycle. A sinusoidal function is then fit to the data to extract the effective wavelength pixel by pixel, yielding an effective wavelength map. A calibrated step height was used to validate the effective wavelength map with results within 1% of the nominal value of the step height. The error sources that contributed to the uncertainty in determining the height of the artifact are also investigated

  16. Wavelength conversion technology

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    1998-01-01

    Optical wavelength conversion is currently attracting much interest. This is because it enables full flexibility and eases management of WDM fibre networks. The tutorial will review existing and potential application areas. Examples of node architectures and network demonstrators that use wavelen...

  17. Wavelength sweepable laser source

    DEFF Research Database (Denmark)

    2014-01-01

    Wavelength sweepable laser source is disclosed, wherein the laser source is a semiconductor laser source adapted for generating laser light at a lasing wavelength. The laser source comprises a substrate, a first reflector, and a second reflector. The first and second reflector together defines...... and having a rest position, the second reflector and suspension together defining a microelectromechanical MEMS oscillator. The MEMS oscillator has a resonance frequency and is adapted for oscillating the second reflector on either side of the rest position.; The laser source further comprises electrical...... connections adapted for applying an electric field to the MEMS oscillator. Furthermore, a laser source system and a method of use of the laser source are disclosed....

  18. Representativeness of shorter measurement sessions in long-term indoor air monitoring.

    Science.gov (United States)

    Maciejewska, M; Szczurek, A

    2015-02-01

    Indoor air quality (IAQ) considerably influences health, comfort and the overall performance of people who spend most of their lives in confined spaces. For this reason, there is a strong need to develop methods for IAQ assessment. The fundamental issue in the quantitative determination of IAQ is the duration of measurements. Its inadequate choice may result in providing incorrect information and this potentially leads to wrong conclusions. The most complete information may be acquired through long-term monitoring. However it is typically perceived as impractical due to time and cost load. The aim of this study was to determine whether long-term monitoring can be adequately represented by a shorter measurement session. There were considered three measurable quantities: temperature, relative humidity and carbon dioxide concentration. They are commonly recognized as indicatives for IAQ and may be readily monitored. Scaled Kullback-Leibler divergence, also called relative entropy, was applied as a measure of data representativeness. We considered long-term monitoring in a range from 1 to 9 months. Based on our work, the representative data on CO2 concentration may be acquired while performing measurements during 20% of time dedicated to long-term monitoring. In the case of temperature and relative humidity the respective time demand was 50% of long-term monitoring. From our results, in indoor air monitoring strategies, there could be considered shorter measurement sessions, while still collecting data which are representative for long-term monitoring.

  19. Wavelength converter placement for different RWA algorithms in wavelength-routed all-optical networks

    Science.gov (United States)

    Chu, Xiaowen; Li, Bo; Chlamtac, Imrich

    2002-07-01

    Sparse wavelength conversion and appropriate routing and wavelength assignment (RWA) algorithms are the two key factors in improving the blocking performance in wavelength-routed all-optical networks. It has been shown that the optimal placement of a limited number of wavelength converters in an arbitrary mesh network is an NP complete problem. There have been various heuristic algorithms proposed in the literature, in which most of them assume that a static routing and random wavelength assignment RWA algorithm is employed. However, the existing work shows that fixed-alternate routing and dynamic routing RWA algorithms can achieve much better blocking performance. Our study in this paper further demonstrates that the wavelength converter placement and RWA algorithms are closely related in the sense that a well designed wavelength converter placement mechanism for a particular RWA algorithm might not work well with a different RWA algorithm. Therefore, the wavelength converter placement and the RWA have to be considered jointly. The objective of this paper is to investigate the wavelength converter placement problem under fixed-alternate routing algorithm and least-loaded routing algorithm. Under the fixed-alternate routing algorithm, we propose a heuristic algorithm called Minimum Blocking Probability First (MBPF) algorithm for wavelength converter placement. Under the least-loaded routing algorithm, we propose a heuristic converter placement algorithm called Weighted Maximum Segment Length (WMSL) algorithm. The objective of the converter placement algorithm is to minimize the overall blocking probability. Extensive simulation studies have been carried out over three typical mesh networks, including the 14-node NSFNET, 19-node EON and 38-node CTNET. We observe that the proposed algorithms not only outperform existing wavelength converter placement algorithms by a large margin, but they also can achieve almost the same performance comparing with full wavelength

  20. Women want taller men more than men want shorter women

    NARCIS (Netherlands)

    Stulp, G.; Buunk, A.P.; Pollet, T.V.

    2013-01-01

    Physical characteristics, such as height, play an important role in human mate preferences. Satisfaction with one's own height and one's partner height seem likely to be related to these preferences. Using a student sample (N= 650), we show that women are not only more selective, but also more

  1. Women want taller men more than men want shorter women

    NARCIS (Netherlands)

    Stulp, Gert; Buunk, Abraham P.; Pollet, Thomas V.

    Physical characteristics, such as height, play an important role in human mate preferences. Satisfaction with ones own height and one's partner height seem likely to be related to these preferences. Using a student sample (N = 650), we show that women are not only more selective, but also more

  2. MIT wavelength tables. Volume 2. Wavelengths by element

    International Nuclear Information System (INIS)

    Phelps, F.M. III.

    1982-01-01

    This volume is the first stage of a project to expand and update the MIT wavelength tables first compiled in the 1930's. For 109,325 atomic emission lines, arranged by element, it presents wavelength in air, wavelength in vacuum, wave number and intensity. All data are stored on computer-readable magnetic tape

  3. Medical necessity for shorter lived radionuclides, specifically pure Iodine-123

    International Nuclear Information System (INIS)

    DeNardo, G.L.; DeNardo, S.J.; Hines, H.H.; Lagunas-Solar, M.C.; Jungerman, J.A.

    1985-01-01

    Iodine-123 has physical and radiochemical characteristics ideal for most tracer procedures performed in patients. Its use is generally preferable to the use of 131 I for diagnosis. The potential for 123 I can be realized only if a radiopharmaceutical of lesser radionuclide contamination is generally and economically available. Iodine-123 produced by direct methods has significant disadvantages relative to quality of procedure and radiation dosimetry. Our experience with 123 I(p,5n) during the past 12 years causes us to vigorously encourage general availability of an 123 I radiopharmaceutical of this quality. Using this product, the authors have prepared radiopharmaceuticals for use in the study of cancer, coagulation, and renal and thyroid diseases

  4. Single wavelength standard wiggler for PEP

    International Nuclear Information System (INIS)

    Brunk, W.; Fischer, G.; Spencer, J.

    1979-03-01

    A 1lambda planar wiggler has been designed that will be used for the initial operation of the 4 to 18 GeV storage ring PEP. Three of these wigglers will be installed symmetrically around the ring at 120 0 intervals in three of six available 5 m straight sections with the purpose of providing: (1) beam size control to obtain better luminosities below 15 GeV, and (2) decreased damping times to obtain better injection rates at lower energies. Design goals are discussed and a description of the final system including cost estimates is given. Expected results and usage in PEP are discussed. Some possibilities for production of synchrotron radiation and beam monitoring with shorter wavelength, multiple-period wigglers at PEP energies are also discussed. Comparison to a wiggler now operating in SPEAR is given

  5. Association of mutations in the hemochromatosis gene with shorter life expectancy

    DEFF Research Database (Denmark)

    Bathum, L; Christiansen, L; Nybo, H

    2001-01-01

    BACKGROUND: To investigate whether the frequency of carriers of mutations in the HFE gene associated with hereditary hemochromatosis diminishes with age as an indication that HFE mutations are associated with increased mortality. It is of value in the debate concerning screening for hereditary...... hemochromatosis to determine the significance of heterozygosity. METHODS: Genotyping for mutations in exons 2 and 4 of the HFE gene using denaturing gradient gel electrophoresis in 1784 participants aged 45 to 100 years from 4 population-based studies: all 183 centenarians from the Danish Centenarian Study, 601...... in the distribution of mutations in exon 2 in the different age groups. CONCLUSIONS: In a high-carrier frequency population like Denmark, mutations in HFE show an age-related reduction in the frequency of heterozygotes for C282Y, which suggests that carrier status is associated with shorter life expectancy....

  6. Enhancement of autonomic and psychomotor arousal by exposures to blue wavelength light: importance of both absolute and relative contents of melanopic component.

    Science.gov (United States)

    Yuda, Emi; Ogasawara, Hiroki; Yoshida, Yutaka; Hayano, Junichiro

    2017-01-31

    Blue light containing rich melanopsin-stimulating (melanopic) component has been reported to enhance arousal level, but it is unclear whether the determinant of the effects is the absolute or relative content of melanopic component. We compared the autonomic and psychomotor arousal effects of melanopic-enriched blue light of organic light-emitting diode (OLED) with those of OLED lights with lesser absolute amount of melanopic component (green light) and with greater absolute but lesser relative content (white light). Using a ceiling light consisting of 120 panels (55 × 55 mm square) of OLED modules with adjustable color and brightness, we examined the effects of blue, green, and white lights (melanopic photon flux densities, 0.23, 0.14, and 0.38 μmol/m 2 /s and its relative content ratios, 72, 17, and 14%, respectively) on heart rate variability (HRV) during exposures and on the performance of psychomotor vigilance test (PVT) after exposures in ten healthy subjects with normal color vision. For each of the three colors, five consecutive 10-min sessions of light exposures were performed in the supine position, interleaved by four 10-min intervals during which 5-min PVT was performed under usual fluorescent light in sitting position. Low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.40 Hz) power and LF-to-HF ratio (LF/HF) of HRV during light exposures and reaction time (RT) and minor lapse (RT >500 ms) of PVT were analyzed. Heart rate was higher and the HF power reflecting autonomic resting was lower during exposures to the blue light than the green and white lights, while LF/HF did not differ significantly. Also, the number of minor lapse and the variation of reaction time reflecting decreased vigilance were lower after exposures to the blue light than the green light. The effects of blue OLED light for maintaining autonomic and psychomotor arousal levels depend on both absolute and relative contents of melanopic component in the light.

  7. Smoking Topography among Korean Smokers: Intensive Smoking Behavior with Larger Puff Volume and Shorter Interpuff Interval.

    Science.gov (United States)

    Kim, Sungroul; Yu, Sol

    2018-05-18

    The difference of smoker's topography has been found to be a function many factors, including sex, personality, nicotine yield, cigarette type (i.e., flavored versus non-flavored) and ethnicity. We evaluated the puffing behaviors of Korean smokers and its association with smoking-related biomarker levels. A sample of 300 participants was randomly recruited from metropolitan areas in South Korea. Topography measures during a 24-hour period were obtained using a CReSS pocket device. Korean male smokers smoked two puffs less per cigarette compared to female smokers (15.0 (13.0⁻19.0) vs. 17.5 (15.0⁻21.0) as the median (Interquartile range)), but had a significantly larger puff volume (62.7 (52.7⁻75.5) mL vs. 53.5 (42.0⁻64.2) mL); p = 0.012). The interpuff interval was similar between men and women (8.9 (6.5⁻11.2) s vs. 8.3 (6.2⁻11.0) s; p = 0.122) but much shorter than other study results. A dose-response association ( p = 0.0011) was observed between daily total puff volumes and urinary cotinine concentrations, after controlling for sex, age, household income level and nicotine addiction level. An understanding of the difference of topography measures, particularly the larger puff volume and shorter interpuff interval of Korean smokers, may help to overcome a potential underestimation of internal doses of hazardous byproducts of smoking.

  8. Wavelength division multiplexing a practical engineering guide

    CERN Document Server

    Grobe, Klaus

    2013-01-01

    In this book, Optical Wavelength Division Multiplexing (WDM) is approached from a strictly practical and application-oriented point of view. Based on the characteristics and constraints of modern fiber-optic components, transport systems and fibers, the text provides relevant rules of thumb and practical hints for technology selection, WDM system and link dimensioning, and also for network-related aspects such as wavelength assignment and resilience mechanisms. Actual 10/40 Gb/s WDM systems are considered, and a preview of the upcoming 100 Gb/s systems and technologies for even higher bit rate

  9. Action spectrum for photobleaching of human lenses by short wavelength visible irradiation

    DEFF Research Database (Denmark)

    Kessel, Line; Larsen, Michael

    2015-01-01

    transmission with increasing laser irradiation. CONCLUSIONS: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained. This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found...... an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths. The results may be used to guide experiments with two-photon bleaching....

  10. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

  11. AWG Filter for Wavelength Interrogator

    Science.gov (United States)

    Black, Richard J. (Inventor); Costa, Joannes M. (Inventor); Faridian, Fereydoun (Inventor); Moslehi, Behzad (Inventor); Sotoudeh, Vahid (Inventor)

    2015-01-01

    A wavelength interrogator is coupled to a circulator which couples optical energy from a broadband source to an optical fiber having a plurality of sensors, each sensor reflecting optical energy at a unique wavelength and directing the reflected optical energy to an AWG. The AWG has a detector coupled to each output, and the reflected optical energy from each grating is coupled to the skirt edge response of the AWG such that the adjacent channel responses form a complementary pair response. The complementary pair response is used to convert an AWG skirt response to a wavelength.

  12. "Catching my wavelength"

    DEFF Research Database (Denmark)

    Jensen, Kirsten Pryds; Bäck-Pettersson, Siv; Segesten, K

    1996-01-01

    The purpose of this article is to describe essential characteristics of an excellent nurse as perceived by women with breast cancer. A descriptive-exploratory research design was used, and 10 Danish women who had breast cancer surgery and treatment more than one year previously and who were still...... related to their perception of an excellent nurse and excellence in nursing...

  13. SHORTER MENSTRUAL CYCLES ASSOCIATED WITH CHLORINATION BY-PRODUCTS IN DRINKING WATER

    Science.gov (United States)

    Shorter Menstrual Cycles Associated with Chlorination by-Products in Drinking Water. Gayle Windham, Kirsten Waller, Meredith Anderson, Laura Fenster, Pauline Mendola, Shanna Swan. California Department of Health Services.In previous studies of tap water consumption we...

  14. Shorter Fallow Cycles Affect the Availability of Noncrop Plant Resources in a Shifting Cultivation System

    Directory of Open Access Journals (Sweden)

    Sarah Paule. Dalle

    2006-12-01

    Full Text Available Shifting cultivation systems, one of the most widely distributed forms of agriculture in the tropics, provide not only crops of cultural significance, but also medicinal, edible, ritual, fuel, and forage resources, which contribute to the livelihoods, health, and cultural identity of local people. In many regions across the globe, shifting cultivation systems are undergoing important changes, one of the most pervasive being a shortening of the fallow cycle. Although there has been much attention drawn to declines in crop yields in conjunction with reductions in fallow times, little if any research has focused on the dynamics of noncrop plant resources. In this paper, we use a data set of 26 fields of the same age, i.e., ~1.5 yr, but differing in the length and frequency of past fallow cycles, to examine the impact of shorter fallow periods on the availability of noncrop plant resources. The resources examined are collected in shifting cultivation fields by the Yucatec Maya in Quintana Roo, Mexico. These included firewood, which is cut from remnant trees and stumps spared at the time of felling, and 17 forage species that form part of the weed vegetation. Firewood showed an overall decrease in basal area with shorter fallow cycles, which was mostly related to the smaller diameter of the spared stumps and trees in short-fallow milpas. In contrast, forage species showed a mixed response. Species increasing in abundance in short-fallow milpas tended to be short-lived herbs and shrubs often with weedy habits, whereas those declining in abundance were predominantly pioneer trees and animal-dispersed species. Coppicing tree species showed a neutral response to fallow intensity. Within the cultural and ecological context of our study area, we expect that declines in firewood availability will be most significant for livelihoods because of the high reliance on firewood for local fuel needs and the fact that the main alternative source of firewood, forest

  15. Minimally invasive oesophagectomy more expensive than open despite shorter length of stay.

    Science.gov (United States)

    Dhamija, Anish; Dhamija, Ankit; Hancock, Jacquelyn; McCloskey, Barbara; Kim, Anthony W; Detterbeck, Frank C; Boffa, Daniel J

    2014-05-01

    The minimally invasive oesophagectomy (MIO) approach offers a number of advantages over open approaches including reduced discomfort, shorter length of stay and a faster recovery to baseline status. On the other hand, minimally invasive procedures typically are longer and consume greater disposable instrumentation, potentially resulting in a greater overall cost. The objective of this study was to compare costs associated with various oesophagectomy approaches for oesophageal cancer. An institutional Resource Information Management System (RIMS) was queried for cost data relating to hospital expenditures (as opposed to billings or collections). The RIMS was searched for patients undergoing oesophagectomy for oesophageal cancer between 2003 and 2012 via minimally invasive, open transthoracic (OTT) (including Ivor Lewis, modified McKeown or thoracoabdominal) or transhiatal approaches. Patients that were converted from minimally invasive to open, or involved hybrid procedures, were excluded. A total of 160 oesophagectomies were identified, including 61 minimally invasive, 35 open transthoracic and 64 transhiatal. Costs on the day of surgery averaged higher in the MIO group ($12 476 ± 2190) compared with the open groups, OTT ($8202 ± 2512, P < 0.0001) or OTH ($5809 ± 2575, P < 0.0001). The median costs associated with the entire hospitalization also appear to be higher in the MIO group ($25 935) compared with OTT ($24 440) and OTH ($15 248). The average length of stay was lowest in the MIO group (11 ± 9 days) compared with OTT (19 ± 18 days, P = 0.006) and OTH (18 ± 28 days P = 0.07). The operative mortality was similar in the three groups (MIO = 3%, OTT = 9% and OTH = 3%). The operating theatre costs associated with minimally invasive oesophagectomy are significantly higher than OTT or OTH approaches. Unfortunately, a shorter hospital stay after MIO does not consistently offset higher surgical expense, as total hospital costs trend higher in the MIO patients. In

  16. "Taller and Shorter": Human 3-D Spatial Memory Distorts Familiar Multilevel Buildings.

    Directory of Open Access Journals (Sweden)

    Thomas Brandt

    Full Text Available Animal experiments report contradictory findings on the presence of a behavioural and neuronal anisotropy exhibited in vertical and horizontal capabilities of spatial orientation and navigation. We performed a pointing experiment in humans on the imagined 3-D direction of the location of various invisible goals that were distributed horizontally and vertically in a familiar multilevel hospital building. The 21 participants were employees who had worked for years in this building. The hypothesis was that comparison of the experimentally determined directions and the true directions would reveal systematic inaccuracy or dimensional anisotropy of the localizations. The study provides first evidence that the internal representation of a familiar multilevel building was distorted compared to the dimensions of the true building: vertically 215% taller and horizontally 51% shorter. This was not only demonstrated in the mathematical reconstruction of the mental model based on the analysis of the pointing experiments but also by the participants' drawings of the front view and the ground plan of the building. Thus, in the mental model both planes were altered in different directions: compressed for the horizontal floor plane and stretched for the vertical column plane. This could be related to human anisotropic behavioural performance of horizontal and vertical navigation in such buildings.

  17. Effects of shorter versus longer storage time of transfused red blood cells in adult ICU patients

    DEFF Research Database (Denmark)

    Rygård, Sofie L; Jonsson, Andreas B; Madsen, Martin B

    2018-01-01

    on the effects of shorter versus longer storage time of transfused RBCs on outcomes in ICU patients. METHODS: We conducted a systematic review with meta-analyses and trial sequential analyses (TSA) of randomised clinical trials including adult ICU patients transfused with fresher versus older or standard issue...... blood. RESULTS: We included seven trials with a total of 18,283 randomised ICU patients; two trials of 7504 patients were judged to have low risk of bias. We observed no effects of fresher versus older blood on death (relative risk 1.04, 95% confidence interval (CI) 0.97-1.11; 7349 patients; TSA......-adjusted CI 0.93-1.15), adverse events (1.26, 0.76-2.09; 7332 patients; TSA-adjusted CI 0.16-9.87) or post-transfusion infections (1.07, 0.96-1.20; 7332 patients; TSA-adjusted CI 0.90-1.27). The results were unchanged by including trials with high risk of bias. TSA confirmed the results and the required...

  18. "Taller and Shorter": Human 3-D Spatial Memory Distorts Familiar Multilevel Buildings.

    Science.gov (United States)

    Brandt, Thomas; Huber, Markus; Schramm, Hannah; Kugler, Günter; Dieterich, Marianne; Glasauer, Stefan

    2015-01-01

    Animal experiments report contradictory findings on the presence of a behavioural and neuronal anisotropy exhibited in vertical and horizontal capabilities of spatial orientation and navigation. We performed a pointing experiment in humans on the imagined 3-D direction of the location of various invisible goals that were distributed horizontally and vertically in a familiar multilevel hospital building. The 21 participants were employees who had worked for years in this building. The hypothesis was that comparison of the experimentally determined directions and the true directions would reveal systematic inaccuracy or dimensional anisotropy of the localizations. The study provides first evidence that the internal representation of a familiar multilevel building was distorted compared to the dimensions of the true building: vertically 215% taller and horizontally 51% shorter. This was not only demonstrated in the mathematical reconstruction of the mental model based on the analysis of the pointing experiments but also by the participants' drawings of the front view and the ground plan of the building. Thus, in the mental model both planes were altered in different directions: compressed for the horizontal floor plane and stretched for the vertical column plane. This could be related to human anisotropic behavioural performance of horizontal and vertical navigation in such buildings.

  19. Quantum interference metrology at deep-UV wavelengths using phase-controlled ultrashort laser pulses

    NARCIS (Netherlands)

    Zinkstok, R. Th; Witte, S.; Ubachs, W.; Hogervorst, W.; Eikema, K. S E

    2005-01-01

    High-resolution metrology at wavelengths shorter than ultraviolet is in general hampered by a limited availability of appropriate laser sources. It is demonstrated that this limitation can be overcome by quantum-interference metrology with frequency up-converted ultrafast laser pulses. The required

  20. Synthesis and physicochemical properties of bis(L-asparaginato) zinc(II): A promising new semiorganic crystal with high laser damage threshold for shorter wavelength generation

    Science.gov (United States)

    Subhashini, R.; Arjunan, S.

    2018-05-01

    An exceedingly apparent nonlinear semiorganic optical crystals of bis(L-asparaginato)zinc(II) [BLAZ], was synthesized by a traditional slow evaporation solution growth technique. The cell parameters were estimated from single crystal X-ray diffraction analysis. Spectroscopic study substantiates the presence of functional groups. The UV spectrum shows the sustenance of wide transparency window and several optical constants, such as extinction coefficient (K), refractive index, optical conductivity and electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data. The fluorescence emission spectrum of the crystal pronounces red emission. The laser induced surface damage threshold of the crystal was measured using Nd:YAG laser. The output intensity of second harmonic generation was estimated using the Kurtz and Perry powder method. The hardness stability was investigated by Vickers microhardness test. The decomposition and thermal stability of the compound were scrutinized by TGA-DSC studies. Dielectric studies were carried out to anatomize the electrical properties of the crystal. SEM analysis reveals the existence of minute crystallites on the growth surface.

  1. Less is more: latent learning is maximized by shorter training sessions in auditory perceptual learning.

    Science.gov (United States)

    Molloy, Katharine; Moore, David R; Sohoglu, Ediz; Amitay, Sygal

    2012-01-01

    The time course and outcome of perceptual learning can be affected by the length and distribution of practice, but the training regimen parameters that govern these effects have received little systematic study in the auditory domain. We asked whether there was a minimum requirement on the number of trials within a training session for learning to occur, whether there was a maximum limit beyond which additional trials became ineffective, and whether multiple training sessions provided benefit over a single session. We investigated the efficacy of different regimens that varied in the distribution of practice across training sessions and in the overall amount of practice received on a frequency discrimination task. While learning was relatively robust to variations in regimen, the group with the shortest training sessions (∼8 min) had significantly faster learning in early stages of training than groups with longer sessions. In later stages, the group with the longest training sessions (>1 hr) showed slower learning than the other groups, suggesting overtraining. Between-session improvements were inversely correlated with performance; they were largest at the start of training and reduced as training progressed. In a second experiment we found no additional longer-term improvement in performance, retention, or transfer of learning for a group that trained over 4 sessions (∼4 hr in total) relative to a group that trained for a single session (∼1 hr). However, the mechanisms of learning differed; the single-session group continued to improve in the days following cessation of training, whereas the multi-session group showed no further improvement once training had ceased. Shorter training sessions were advantageous because they allowed for more latent, between-session and post-training learning to emerge. These findings suggest that efficient regimens should use short training sessions, and optimized spacing between sessions.

  2. Wavelength dependence of interstellar polarization

    International Nuclear Information System (INIS)

    Mavko, G.E.

    1974-01-01

    The wavelength dependence of interstellar polarization was measured for twelve stars in three regions of the Milky Way. A 120A bandpass was used to measure the polarization at a maximum of sixteen wavelengths evenly spaced between 2.78μ -1 (3600A) and 1.28μ -1 (7800A). For such a wide wavelength range, the wavelength resolution is superior to that of any previously reported polarization measurements. The new scanning polarimeter built by W. A. Hiltner of the University of Michigan was used for the observations. Very broad structure was found in the wavelength dependence of the polarization. Extensive investigations were carried out to show that the structure was not caused by instrumental effects. The broad structure observed is shown to be in agreement with concurrent extinction measurements for the same stars. Also, the observed structure is of the type predicted when a homogeneous silicate grain model is fitted to the observed extinction. The results are in agreement with the hypothesis that the very broad band structure seen in the extinction is produced by the grains. (Diss. Abstr. Int., B)

  3. Short wavelength striations on expanding plasma clouds

    International Nuclear Information System (INIS)

    Winske, D.; Gary, S.P.

    1989-01-01

    The growth and evolution of short wavelength (< ion gyroradius) flute modes on a plasma expanding across an ambient magnetic field have been actively studied in recent years, both by means of experiments in the laboratory as well as in space and through numerical simulations. We review the relevant observations and simulations results, discuss the instability mechanism and related linear theory, and describe recent work to bring experiments and theory into better agreement. 30 refs., 6 figs

  4. Negative refraction by a planar Ag/SiO2 multilayer at ultraviolet wavelength to the limit of silver

    Directory of Open Access Journals (Sweden)

    J. Zhao

    2014-04-01

    Full Text Available For planar structured hyperbolic metamaterial, the shortest wavelength achievable for negative refraction is often limited by dielectric layers, which are usually wide band gap semiconductors that absorb light strongly at wavelength shorter than their absorption edge. Here we proposed that using SiO2 may break such limitation based on effective medium theory. Through calculation and simulation we demonstrated broad angle negative refraction by a planar Ag/SiO2 layered structure at wavelength down to 326 nm. Its imaging and focusing abilities were also presented. The lower limit of wavelength here is defined by the property of silver, whose permittivity turns positive below 324 nm.

  5. An aluminium nitride light-emitting diode with a wavelength of 210 nanometres.

    Science.gov (United States)

    Taniyasu, Yoshitaka; Kasu, Makoto; Makimoto, Toshiki

    2006-05-18

    Compact high-efficiency ultraviolet solid-state light sources--such as light-emitting diodes (LEDs) and laser diodes--are of considerable technological interest as alternatives to large, toxic, low-efficiency gas lasers and mercury lamps. Microelectronic fabrication technologies and the environmental sciences both require light sources with shorter emission wavelengths: the former for improved resolution in photolithography and the latter for sensors that can detect minute hazardous particles. In addition, ultraviolet solid-state light sources are also attracting attention for potential applications in high-density optical data storage, biomedical research, water and air purification, and sterilization. Wide-bandgap materials, such as diamond and III-V nitride semiconductors (GaN, AlGaN and AlN; refs 3-10), are potential materials for ultraviolet LEDs and laser diodes, but suffer from difficulties in controlling electrical conduction. Here we report the successful control of both n-type and p-type doping in aluminium nitride (AlN), which has a very wide direct bandgap of 6 eV. This doping strategy allows us to develop an AlN PIN (p-type/intrinsic/n-type) homojunction LED with an emission wavelength of 210 nm, which is the shortest reported to date for any kind of LED. The emission is attributed to an exciton transition, and represents an important step towards achieving exciton-related light-emitting devices as well as replacing gas light sources with solid-state light sources.

  6. Wavelength conversion techniques and devices

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Mikkelsen, Benny; Hansen, Peter Bukhave

    1997-01-01

    Taking into account the requirements to the converters e.g., bit rate transparency (at least up to 10 Gbit/s), polarisation independence, wavelength independence, moderate input power levels, high signal-to-noise ratio and high extinction ratio interferometric wavelength convertors are very...... interesting for use in WDM optical fibre networks. However, the perfect converter has probably not yet been fabricated and new techniques such as conversion relying on cross-absorption modulation in electro-absorption modulators might also be considered in pursue of effective conversion devices...

  7. Sub-wavelength plasmon laser

    Science.gov (United States)

    Bora, Mihail; Bond, Tiziana C.

    2016-04-19

    A plasmonic laser device has resonant nanocavities filled with a gain medium containing an organic dye. The resonant plasmon frequencies of the nanocavities are tuned to align with both the absorption and emission spectra of the dye. Variables in the system include the nature of the dye and the wavelength of its absorption and emission, the wavelength of the pumping radiation, and the resonance frequencies of the nanocavities. In addition the pumping frequency of the dye is selected to be close to the absorption maximum.

  8. Wavelength standards in the infrared

    CERN Document Server

    Rao, KN

    2012-01-01

    Wavelength Standards in the Infrared is a compilation of wavelength standards suitable for use with high-resolution infrared spectrographs, including both emission and absorption standards. The book presents atomic line emission standards of argon, krypton, neon, and xenon. These atomic line emission standards are from the deliberations of Commission 14 of the International Astronomical Union, which is the recognized authority for such standards. The text also explains the techniques employed in determining spectral positions in the infrared. One of the techniques used includes the grating con

  9. Hypermetabolism in ALS is associated with greater functional decline and shorter survival.

    Science.gov (United States)

    Steyn, Frederik J; Ioannides, Zara A; van Eijk, Ruben P A; Heggie, Susan; Thorpe, Kathryn A; Ceslis, Amelia; Heshmat, Saman; Henders, Anjali K; Wray, Naomi R; van den Berg, Leonard H; Henderson, Robert D; McCombe, Pamela A; Ngo, Shyuan T

    2018-04-29

    To determine the prevalence of hypermetabolism, relative to body composition, in amyotrophic lateral sclerosis (ALS) and its relationship with clinical features of disease and survival. Fifty-eight patients with clinically definite or probable ALS as defined by El Escorial criteria, and 58 age and sex-matched control participants underwent assessment of energy expenditure. Our primary outcome was the prevalence of hypermetabolism in cases and controls. Longitudinal changes in clinical parameters between hypermetabolic and normometabolic patients with ALS were determined for up to 12 months following metabolic assessment. Survival was monitored over a 30-month period following metabolic assessment. Hypermetabolism was more prevalent in patients with ALS than controls (41% vs 12%, adjusted OR=5.4; pALS. Mean lower motor neuron score (SD) was greater in hypermetabolic patients when compared with normometabolic patients (4 (0.3) vs 3 (0.7); p=0.04). In the 12 months following metabolic assessment, there was a greater change in Revised ALS Functional Rating Scale score in hypermetabolic patients when compared with normometabolic patients (-0.68 points/month vs -0.39 points/month; p=0.01). Hypermetabolism was inversely associated with survival. Overall, hypermetabolism increased the risk of death during follow-up to 220% (HR 3.2, 95% CI 1.1 to 9.4, p=0.03). Hypermetabolic patients with ALS have a greater level of lower motor neuron involvement, faster rate of functional decline and shorter survival. The metabolic index could be important for informing prognosis in ALS. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  10. Prenatal paracetamol exposure is associated with shorter anogenital distance in male infants

    Science.gov (United States)

    Fisher, B.G.; Thankamony, A.; Hughes, I.A.; Ong, K.K.; Dunger, D.B.; Acerini, C.L.

    2016-01-01

    weeks of gestation, but not any other period, was associated with shorter AGD (by 0.27 SD, 95% CI 0.06–0.48, P = 0.014) from birth to 24 months of age. This reduction was independent of body size. Paracetamol exposure was not related to penile length or testicular descent. LIMITATIONS, REASONS FOR CAUTION Confounding by other drugs or endocrine-disrupting chemicals cannot be discounted. The cohort was not fully representative of pregnant women in the UK, particularly in terms of maternal ethnicity and smoking prevalence. There is likely to have been misclassification of paracetamol exposure due to recall error. WIDER IMPLICATIONS OF THE FINDINGS Our observational findings support experimental evidence that intrauterine paracetamol exposure during the MPW may adversely affect male reproductive development. STUDY FUNDING/COMPETING INTERESTS This work was supported by a European Union Framework V programme, the World Cancer Research Fund International, the Medical Research Council (UK), the Newlife Foundation for Disabled Children, the Evelyn Trust, the Mothercare Group Foundation, Mead Johnson Nutrition, and the National Institute for Health Research Cambridge Comprehensive Biomedical Research Centre. The authors declare no conflict of interest. PMID:27609981

  11. Wavelength switching in an optical klystron

    International Nuclear Information System (INIS)

    Berryman, K.W.; Smith, T.I.

    1995-01-01

    A symmetric optical klystron consists of two identical undulator sections separated a dispersive section. For a device of a given length, an optical klystron is capable of producing much more bunching, and therefore more gain, than a traditional undulator. Another consequence of introducing dispersion between two undulator sections is that the overall spontaneous radiation pattern results from the interference between the two undulator sections, and as such resembles a standard undulator radiation pattern modulated by a sinusoidal interference term. The presence of several wavelength peaks in the spontaneous lineshape implies an equal number of peaks in the gain spectrum. If the strength of the dispersion section is adjusted to provide nearly equal gain on the two largest of these peaks, then they will compete, and the FEL may switch wavelengths based on noise, cavity length, or other perturbations. We provide the first observations of this behavior, using the FIREFLY system at the Stanford Picosecond FEL Center. In FIREFLY, relative wavelength switching by more than 3%--more than twice the laser linewidth-has been observed by varying dispersion section strength, while at intermediate points stable switching has also been observed as a function of cavity length

  12. Wavelength-tunable laser based on nonlinear dispersive-wave generation in a tapered optical waveguide

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a method and a wavelength tunable laser comprising a first laser source configured to emit a first optical pulse having a pump wavelength, the first optical pulse being emitted in a first longitudinal direction. Furthermore, the wavelength tunable laser comprises...... a waveguide extending in the first longitudinal direction, the waveguide having longitudinally varying phase matching conditions, the waveguide being configured to generate a second optical pulse with a centre wavelength upon receiving the first optical pulse, wherein the wavelength tunable laser...... is configured to tune the centre wavelength of the second optical pulse by varying at least one pulse property of the first optical pulse....

  13. Wavelength dependence of the bidirectional reflectance distribution function (BRDF) of beach sands.

    Science.gov (United States)

    Doctor, Katarina Z; Bachmann, Charles M; Gray, Deric J; Montes, Marcos J; Fusina, Robert A

    2015-11-01

    The wavelength dependence of the dominant directional reflective properties of beach sands was demonstrated using principal component analysis and the related correlation matrix. In general, we found that the hyperspectral bidirectional reflectance distribution function (BRDF) of beach sands has weak wavelength dependence. Its BRDF varies slightly in three broad wavelength regions. The variations are more evident in surfaces of greater visual roughness than in smooth surfaces. The weak wavelength dependence of the BRDF of beach sand can be captured using three broad wavelength regions instead of hundreds of individual wavelengths.

  14. Review of short wavelength lasers

    International Nuclear Information System (INIS)

    Hagelstein, P.L.

    1985-01-01

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references

  15. Review of short wavelength lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hagelstein, P.L.

    1985-03-18

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.

  16. Dual-wavelength phase-shifting digital holography selectively extracting wavelength information from wavelength-multiplexed holograms.

    Science.gov (United States)

    Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro

    2015-06-15

    Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.

  17. YAOPBM-II: extension to higher degrees and to shorter time series

    Energy Technology Data Exchange (ETDEWEB)

    Korzennik, S G [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)], E-mail: skorzennik@cfa.harvard.edu

    2008-10-15

    In 2005, I presented a new fitting methodology (Yet AnOther Peak Bagging Method -YAOPBM), derived for very-long time series (2088-day-long) and applied it to low degree modes, {iota} {<=} 25. That very-long time series was also sub-divided into shorter segments (728-day-long) that were each fitted over the same range of degrees, to estimate changes with solar activity levels. I present here the extension of this method in several 'directions': a) to substantially higher degrees ({iota} {<=} 125); b) to shorter time series (364- and 182-day-long); and c) to additional 728-day-long segments, covering now some 10 years of observations. I discuss issues with the fitting, namely the leakage matrix, and the f- and p1 mode at very low frequencies, and I present some of the characteristics of the observed temporal changes.

  18. Is equity confined to the shorter term projects - and if not, what does it need?

    International Nuclear Information System (INIS)

    Cryan, T.

    1996-01-01

    There are two types of equity investor generally found in shorter term energy projects: energy project developers or sponsors who view a given project as buying or building a business; and financial investors who have viewed an investment as buying a stream of cash flows. This article examines the objectives and needs of these two investor groups, and discusses the principal issues which govern their respective decision-making process. (author)

  19. How do shorter working hours affect employee wellbeing? : Shortening working time in Finland

    OpenAIRE

    Lahdenperä, Netta

    2017-01-01

    The way work is done is dramatically changing due to digital breakthroughs. Generation Y is entering the workforce with a changed attitude towards work as organizations are increasing their focus towards employee wellbeing. Organizations who adopt the new model of work and understand the importance of the wellbeing of their staff are leading the transition to a more efficient business, better working life and a healthier planet. The thesis explores the numerous effects of shorter working...

  20. Local Analysis Approach for Short Wavelength Geopotential Variations

    Science.gov (United States)

    Bender, P. L.

    2009-12-01

    The value of global spherical harmonic analyses for determining 15 day to 30 day changes in the Earth's gravity field has been demonstrated extensively using data from the GRACE mission and previous missions. However, additional useful information appears to be obtainable from local analyses of the data. A number of such analyses have been carried out by various groups. In the energy approximation, the changes in the height of the satellite altitude geopotential can be determined from the post-fit changes in the satellite separation during individual one-revolution arcs of data from a GRACE-type pair of satellites in a given orbit. For a particular region, it is assumed that short wavelength spatial variations for the arcs crossing that region during a time T of interest would be used to determine corrections to the spherical harmonic results. The main issue in considering higher measurement accuracy in future missions is how much improvement in spatial resolution can be achieved. For this, the shortest wavelengths that can be determined are the most important. And, while the longer wavelength variations are affected by mass distribution changes over much of the globe, the shorter wavelength ones hopefully will be determined mainly by more local changes in the mass distribution. Future missions are expected to have much higher accuracy for measuring changes in the satellite separation than GRACE. However, how large an improvement in the derived results in hydrology will be achieved is still very much a matter of study, particularly because of the effects of uncertainty in the time variations in the atmospheric and oceanic mass distributions. To be specific, it will be assumed that improving the spatial resolution in continental regions away from the coastlines is the objective, and that the satellite altitude is in the range of roughly 290 to 360 km made possible for long missions by drag-free operation. The advantages of putting together the short wavelength

  1. On the influence of crystal size and wavelength on native SAD phasing.

    Science.gov (United States)

    Liebschner, Dorothee; Yamada, Yusuke; Matsugaki, Naohiro; Senda, Miki; Senda, Toshiya

    2016-06-01

    Native SAD is an emerging phasing technique that uses the anomalous signal of native heavy atoms to obtain crystallographic phases. The method does not require specific sample preparation to add anomalous scatterers, as the light atoms contained in the native sample are used as marker atoms. The most abundant anomalous scatterer used for native SAD, which is present in almost all proteins, is sulfur. However, the absorption edge of sulfur is at low energy (2.472 keV = 5.016 Å), which makes it challenging to carry out native SAD phasing experiments as most synchrotron beamlines are optimized for shorter wavelength ranges where the anomalous signal of sulfur is weak; for longer wavelengths, which produce larger anomalous differences, the absorption of X-rays by the sample, solvent, loop and surrounding medium (e.g. air) increases tremendously. Therefore, a compromise has to be found between measuring strong anomalous signal and minimizing absorption. It was thus hypothesized that shorter wavelengths should be used for large crystals and longer wavelengths for small crystals, but no thorough experimental analyses have been reported to date. To study the influence of crystal size and wavelength, native SAD experiments were carried out at different wavelengths (1.9 and 2.7 Å with a helium cone; 3.0 and 3.3 Å with a helium chamber) using lysozyme and ferredoxin reductase crystals of various sizes. For the tested crystals, the results suggest that larger sample sizes do not have a detrimental effect on native SAD data and that long wavelengths give a clear advantage with small samples compared with short wavelengths. The resolution dependency of substructure determination was analyzed and showed that high-symmetry crystals with small unit cells require higher resolution for the successful placement of heavy atoms.

  2. Making Displaced Holograms At Two Wavelengths

    Science.gov (United States)

    Witherow, William K.; Ecker, Andreas

    1989-01-01

    Two-wavelength holographic system augmented with pair of prisms to introduce small separation between holograms formed simultaneously at two wavelengths on holographic plate. Principal use in study of flows. Gradients in index of refraction of fluid caused by variations in temperature, concentration, or both. Holography at one wavelength cannot be used to distinguish between two types of variations. Difference between spacings of fringes in photographs reconstructed from holograms taken simultaneously at two different wavelengths manipulated mathematically to determine type of variation.

  3. Physical activity during video capsule endoscopy correlates with shorter bowel transit time.

    Science.gov (United States)

    Stanich, Peter P; Peck, Joshua; Murphy, Christopher; Porter, Kyle M; Meyer, Marty M

    2017-09-01

     Video capsule endoscopy (VCE) is limited by reliance on bowel motility for propulsion, and lack of physical activity has been proposed as a cause of incomplete studies. Our aim was to prospectively investigate the association between physical activity and VCE bowel transit.  Ambulatory outpatients receiving VCE were eligible for the study. A pedometer was attached at the time of VCE ingestion and step count was recorded at the end of the procedure. VCE completion was assessed by logistic regression models, which included step count (500 steps as one unit). Total transit time was analyzed by Cox proportional hazards models. The hazard ratios (HR) with 95 % confidence interval (CI) indicated the "hazard" of completion, such that HRs > 1 indicated a reduced transit time.  A total of 100 patients were included. VCE was completed in 93 patients (93 %). The median step count was 2782 steps. Step count was not significantly associated with VCE completion (odds ratio 1.45, 95 %CI 0.84, 2.49). Pedometer step count was significantly associated with shorter total, gastric, and small-bowel transit times (HR 1.09, 95 %CI 1.03, 1.16; HR 1.05, 95 %CI 1.00, 1.11; HR 1.07, 95 %CI 1.01, 1.14, respectively). Higher body mass index (BMI) was significantly associated with VCE completion (HR 1.87, 95 %CI 1.18, 2.97) and shorter bowel transit times (HR 1.05, 95 %CI 1.02, 1.08).  Increased physical activity during outpatient VCE was associated with shorter bowel transit times but not with study completion. In addition, BMI was a previously unreported clinical characteristic associated with VCE completion and should be included as a variable of interest in future studies.

  4. Homework schedule: an important factor associated with shorter sleep duration among Chinese school-aged children.

    Science.gov (United States)

    Li, Shenghui; Yang, Qian; Chen, Zhe; Jin, Xingming; Jiang, Fan; Shen, Xiaoming

    2014-09-03

    This study was designed to examine the hypothesis that homework schedule has adverse impacts on Chinese children's sleep-wake habits and sleep duration. A random sample of 19,299 children aged 5.08 to 11.99 years old participated in a large, cross-sectional survey. A parent-administered questionnaire was completed to quantify children's homework schedule and sleep behaviors. Generally, it was demonstrated that more homework schedule was significantly associated with later bedtime, later wake time, and shorter sleep duration. Among all sleep variables, bedtime and sleep duration during weekdays appeared to be most affected by homework schedule, especially homework schedule during weekdays.

  5. Reemission spectra and inelastic processes at interaction of attosecond and shorter duration electromagnetic pulses with atoms

    International Nuclear Information System (INIS)

    Makarov, D.N.; Matveev, V.I.

    2017-01-01

    Inelastic processes and the reemission of attosecond and shorter electromagnetic pulses by atoms have been considered within the analytical solution of the Schrödinger equation in the sudden perturbation approximation. A method of calculations with the exact inclusion of spatial inhomogeneity of the field of an ultrashort pulse and the momenta of photons in the reemission processes has been developed. The probabilities of inelastic processes and spectra of reemission of ultrashort electromagnetic pulses by one- and many-electron atoms have been calculated. The results have been presented in the form of analytical formulas.

  6. Wavelength-selective bleaching of the optical spectra of trapped electrons in organic glasses. II

    International Nuclear Information System (INIS)

    Paraszczak, J.; Willard, J.E.

    1979-01-01

    Further resolution of the inhomogeneous optical spectra of trapped electrons (e - /sub t/) in organic glasses has been obtained from wavelength selective bleaching and thermal decay studies on 3-methylpentane-d 14 (3MP-d 14 ) and 2-methyltetrahydrofuran (MTHF) following γ irradiation in the temperature region of 20 K, and limits on the degree of resolution achievable have been indicated. Exposure of 3MP-d 14 to light of wavelengths >2100 nm (from a tunable laser) reduces the optical densities at the bleaching wavelength and longer to zero, while ''peeling off'' a portion of the O.D. at all shorter wavelengths but leaving the remainder of the spectrum unaffected. The fraction of the integrated optical spectrum, ∫OD d (eV), removed by bleaching at each wavelength tested, and also by thermal decay, is equivalent to the fraction of the total e - /sub t/ spins removed and measured by ESR. 1064 nm light bleaches the spectrum nearly uniformly, confirming that the spectra of all of the e - /sub t/ have blue tails with similar ease of bleaching. Heretofore unobserved low temperature thermal decay of e - /sub t/ occurs at 20 and 40 K (20% of the spin concentration in 30 min, 35% in 3h). The rate of decay of the optical spectrum decreases with decreasing wavelength of observation (2.5, 2.2, 1.8, and 1.5 μ), but at each wavelength is the same at 40 K as at 20 K, consistent

  7. Shorter telomeres in peripheral blood mononuclear cells from older persons with sarcopenia: results from an exploratory study

    Directory of Open Access Journals (Sweden)

    Emanuele eMarzetti

    2014-08-01

    Full Text Available Background. Telomere shortening in peripheral blood mononuclear cells (PBMCs has been associated with biological age and several chronic degenerative diseases. However, the relationship between telomere length and sarcopenia, a hallmark of the aging process, is unknown. The aim of the present study was therefore to determine whether PBMC telomeres obtained from sarcopenic older persons were shorter relative to non-sarcopenic peers. We further explored if PBMC telomere length was associated with frailty, a major clinical correlate of sarcopenia.Methods. Analyses were conducted in 142 persons aged >/= 65 years referred to a geriatric outpatient clinic (University Hospital. The presence of sarcopenia was established according to the European Working Group on Sarcopenia in Older People criteria, with bioelectrical impedance analysis used for muscle mass estimation. The frailty status was determined by both the Fried’s criteria (physical frailty, PF and a modified Rockwood’s frailty index (FI. Telomere length was measured in PBMCs by quantitative real-time polymerase chain reaction according to the Telomere/Single copy gene ratio (T/S method.Results. Among 142 outpatients (mean age 75.0 ± 6.5 years, 59.2% women, sarcopenia was diagnosed in 23 individuals (19.3%. The PF phenotype was detected in 74 participants (52.1%. The average FI score was 0.46 ± 0.17. PBMC telomeres were shorter in sarcopenic subjects (T/S = 0.21; 95% CI: 0.18 – 0.24 relative to non-sarcopenic individuals (T/S = 0.26; 95%: CI: 0.24 – 0.28; p = 0.01, independent of age, gender, smoking habit, or comorbidity. No significant associations were determined between telomere length and either PF or FI.Conclusion. PBMC telomere length, expressed as T/S values, is shorter in older outpatients with sarcopenia. The cross-sectional assessment of PBMC telomere length is not sufficient at capturing the complex, multidimensional syndrome of frailty.

  8. Shorter preschool, leukocyte telomere length is associated with obesity at age 9 in Latino children.

    Science.gov (United States)

    Kjaer, T W; Faurholt-Jepsen, D; Mehta, K M; Christensen, V B; Epel, E; Lin, J; Blackburn, E; Wojcicki, J M

    2018-04-01

    The aim of this study was to determine the potential role of leukocyte telomere length as a biomarker for development of childhood obesity in a low-income Latino population. A birth cohort of Latino children (N = 201) in San Francisco (recruited May 2006-May 2007) was followed until age 9 and assessed annually for obesity and dietary intake. Leukocyte telomere length was measured at 4 and 5 years (n = 102) and assessed as a predictor for obesity at age 9, adjusting for known risk factors. Furthermore, leukocyte telomere length at age 4 and 5 was evaluated as a possible mediator of the relationship between excessive sugar-sweetened beverage consumption and obesity at age 9. Shorter leukocyte telomere length in preschoolers was associated with obesity at age 9 (adjusted odds ratio 0.35, 95% confidence interval 0.13-0.94) after adjustment for known risk factors. Telomere length mediated 11% of the relationship between excessive sugar-sweetened beverage consumption and obesity. Shorter leukocyte telomere length may be an indicator of future obesity risk in high-risk populations as it is particularly sensitive to damage from oxidative stress exposure, including those from sugar-sweetened beverages. © 2017 World Obesity Federation.

  9. Applicability of the shorter ‘Bangladesh regimen’ in high multidrug-resistant tuberculosis settings

    Directory of Open Access Journals (Sweden)

    Giovanni Sotgiu

    2017-03-01

    Full Text Available In spite of the recent introduction of two new drugs (delamanid and bedaquiline and a few repurposed compounds to treat multidrug-resistant and extensively drug-resistant tuberculosis (MDR- and XDR-TB, clinicians are facing increasing problems in designing effective regimens in severe cases. Recently a 9 to 12-month regimen (known as the ‘Bangladesh regimen’ proved to be effective in treating MDR-TB cases. It included an initial phase of 4 to 6 months of kanamycin, moxifloxacin, prothionamide, clofazimine, pyrazinamide, high-dose isoniazid, and ethambutol, followed by 5 months of moxifloxacin, clofazimine, pyrazinamide, and ethambutol. However, recent evidence from Europe and Latin America identified prevalences of resistance to the first-line drugs in this regimen (ethambutol and pyrazinamide exceeding 60%, and of prothionamide exceeding 50%. Furthermore, the proportions of resistance to the two most important pillars of the regimen – quinolones and kanamycin – were higher than 40%. Overall, only 14 out of 348 adult patients (4.0% were susceptible to all of the drugs composing the regimen, and were therefore potentially suitable for the ‘shorter regimen’. A shorter, cheaper, and well-tolerated MDR-TB regimen is likely to impact the number of patients treated and improve adherence if prescribed to the right patients through the systematic use of rapid MTBDRsl testing.

  10. Are Shorter Versions of the Positive and Negative Syndrome Scale (PANSS) Doable? A Critical Review.

    Science.gov (United States)

    Lindenmayer, Jean-Pierre

    2017-12-01

    The Positive and Negative Syndrome Scale (PANSS) is a well-established assessment tool for measuring symptom severity in schizophrenia. Researchers and clinicians have been interested in the development of a short version of the PANSS that could reduce the burden of its administration for patients and raters. The author presents a comprehensive overview of existing brief PANSS measures, including their strengths and limitations, and discusses some possible next steps. There are two available scales that offer a reduced number of original PANSS items: PANSS-14 and PANSS-19; and two shorter versions that include six items: Brief PANSS and PANSS-6. The PANSS-6 has been tested quite extensively in established trials and appears to demonstrate high sensitivity to change and an established cut off definition for remission. Prospective testing in new antipsychotic treatment trials is still required for these shorter versions of PANSS. In addition, they need to be supplemented with interview guides, as well as provide conversion formulas to translate total scores from the short PANSS versions to the PANSS-30. Both short versions of the PANSS are essentially designed to evaluate response to antipsychotic treatment. Future PANSS scale development needs to address specific measurement of treatment-responsive positive symptoms by including treatment-sensitive items, as well as illness-phase specific PANSS tools.

  11. Wavelength modulation spectroscopy of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kohn, S.E.

    1977-10-01

    The use of modulation spectroscopy to study the electronic properties of solids has been very productive. The construction of a wide range Wavelength Modulation Spectrometer to study the optical properties of solids is described in detail. Extensions of the working range of the spectrometer into the vacuum ultraviolet are discussed. Measurements of the reflectivity and derivative reflectivity spectra of the lead chalcogenides, the chalcopyrite ZnGeP/sub 2/, the layer compounds GaSe and GaS and their alloys, the ferroelectric SbSI, layer compounds SnS/sub 2/ and SnSe/sub 2/, and HfS/sub 2/ were made. The results of these measurements are presented along with their interpretation in terms of band structure calculations.

  12. Long-wavelength microinstabilities in toroidal plasmas

    International Nuclear Information System (INIS)

    Tang, W.W.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

  13. Dye mixtures for ultrafast wavelength shifters

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, S.; Liu, L.; Palsule, C.; Borst, W.; Wigmans, R. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Physics; Barashkov, N. [Karpov Inst. of Physical Chemistry, Moscow (Russian Federation)

    1994-12-31

    Particle detectors based on scintillation processes have been used since the discovery of radium about 100 years ago. The fast signals that can be obtained with these detectors, although often considered a nice asset, were rarely essential for the success of experiments. However, the new generation of high energy particle accelerators require particle detectors with fast response time. The authors have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5--4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations.

  14. Dye mixtures for ultrafast wavelength shifters

    International Nuclear Information System (INIS)

    Gangopadhyay, S.; Liu, L.; Palsule, C.; Borst, W.; Wigmans, R.

    1994-01-01

    Particle detectors based on scintillation processes have been used since the discovery of radium about 100 years ago. The fast signals that can be obtained with these detectors, although often considered a nice asset, were rarely essential for the success of experiments. However, the new generation of high energy particle accelerators require particle detectors with fast response time. The authors have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5--4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations

  15. Wavelength calibration of an imaging spectrometer based on Savart interferometer

    Science.gov (United States)

    Li, Qiwei; Zhang, Chunmin; Yan, Tingyu; Quan, Naicheng; Wei, Yutong; Tong, Cuncun

    2017-09-01

    The basic principle of Fourier-transform imaging spectrometer (FTIS) based on Savart interferometer is outlined. The un-identical distribution of the optical path difference which leads to the wavelength drift of each row of the interferogram is analyzed. Two typical methods for wavelength calibration of the presented system are described. The first method unifies different spectral intervals and maximum spectral frequencies of each row by a reference monochromatic light with known wavelength, and the dispersion compensation of Savart interferometer is also involved. The second approach is based on the least square fitting which builds the functional relation between recovered wavelength, row number and calibrated wavelength by concise equations. The effectiveness of the two methods is experimentally demonstrated with monochromatic lights and mixed light source across the detecting band of the system, and the results indicate that the first method has higher precision and the mean root-mean-square error of the recovered wavelengths is significantly reduced from 19.896 nm to 1.353 nm, while the second method is more convenient to implement and also has good precision of 2.709 nm.

  16. Wavelength stabilized multi-kW diode laser systems

    Science.gov (United States)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

    2015-03-01

    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  17. Discrimination of Urban Spaces with Different Level of Restorativeness Based on the Original and on a Shorter Version of Hartig et al.’s Perceived Restorativeness Scale

    Directory of Open Access Journals (Sweden)

    Fátima Negrín

    2017-10-01

    Full Text Available Restorativeness is defined as the potential of the environment to re-establish certain cognitive capacities related to human information processing. The most frequently used instrument for evaluating the restorativeness of places is the Perceived Restorativeness Scale, proposed by Hartig et al. (1991. Later on, shorter versions of the Perceived Restorativeness Scale were proposed. The aim of this work is to evaluate the discriminatory capacity of the original and of a shorter Spanish version of the PRS, considering urban settings previously selected for having different level of restorativeness, according to expert’s criteria. The study involved 244 students and used a 3 × 2 mixed experimental design, with two independent variables: Restorativeness of a place (between-subjects, which was manipulated by showing pictures of settings selected with varying levels of restorativeness (high, medium, low, and length of the scale (within-subjects, which was manipulated by asking subjects to fill in both the original and a shorter version of the PRS. The order of presentation of the two scales was counterbalanced. Results show an appropriate reliability for both version of the scale. Items of being-away, fascination, and coherence of the shorter scale correlate more strongly with the corresponding factor of the original scale, compared to the others factors. Both scales produce similar values for the perceived restorativeness of the different places, except for places with low restorativeness.

  18. The effect of shorter exposure versus prolonged exposure on treatment outcome in Tourette syndrome and chronic tic disorders - an open trial.

    Science.gov (United States)

    van de Griendt, Jolande M T M; van Dijk, Maarten K; Verdellen, Cara W J; Verbraak, Marc J P M

    2018-01-11

    Exposure and response prevention has shown to be an effective strategy and is considered a first-line intervention in the behavioural treatment of tic disorders. Prior research demonstrated significant tic reduction after 12 two hour sessions. In this open trial, the question is addressed whether, relative to these prolonged sessions, exposure sessions of shorter duration yield differential outcome for patients with tic disorders. A total of 29 patients diagnosed with Tourette syndrome (TS) or chronic tic disorder were treated with shorter exposure sessions (1 h), and these data were compared to the data from a study about prolonged exposure (2 h, n = 21). Outcome was measured by the Yale Global Tic Severity Scale (YGTSS). Results suggest that after taking the difference in illness duration between the two groups into account, the effectiveness of shorter exposure sessions is not inferior to that of prolonged exposure. Results suggest that treatment with shorter exposure might be more efficient and more patients can be reached. Future research is needed to gain more insight into the mechanisms underlying the efficacy of behavioural treatments for tics.

  19. Spindle assembly checkpoint protein expression correlates with cellular proliferation and shorter time to recurrence in ovarian cancer.

    LENUS (Irish Health Repository)

    McGrogan, Barbara

    2014-07-01

    Ovarian carcinoma (OC) is the most lethal of the gynecological malignancies, often presenting at an advanced stage. Treatment is hampered by high levels of drug resistance. The taxanes are microtubule stabilizing agents, used as first-line agents in the treatment of OC that exert their apoptotic effects through the spindle assembly checkpoint. BUB1-related protein kinase (BUBR1) and mitotic arrest deficient 2 (MAD2), essential spindle assembly checkpoint components, play a key role in response to taxanes. BUBR1, MAD2, and Ki-67 were assessed on an OC tissue microarray platform representing 72 OC tumors of varying histologic subtypes. Sixty-one of these patients received paclitaxel and platinum agents combined; 11 received platinum alone. Overall survival was available for all 72 patients, whereas recurrence-free survival (RFS) was available for 66 patients. Increased BUBR1 expression was seen in serous carcinomas, compared with other histologies (P = .03). Increased BUBR1 was significantly associated with tumors of advanced stage (P = .05). Increased MAD2 and BUBR1 expression also correlated with increased cellular proliferation (P < .0002 and P = .02, respectively). Reduced MAD2 nuclear intensity was associated with a shorter RFS (P = .03), in ovarian tumors of differing histologic subtype (n = 66). In this subgroup, for those women who received paclitaxel and platinum agents combined (n = 57), reduced MAD2 intensity also identified women with a shorter RFS (P < .007). For the entire cohort of patients, irrespective of histologic subtype or treatment, MAD2 nuclear intensity retained independent significance in a multivariate model, with tumors showing reduced nuclear MAD2 intensity identifying patients with a poorer RFS (P = .05).

  20. Wavelength Selection For Laser Raman Spectroscopy of Putative Martian Habitats and Biomolecules

    Science.gov (United States)

    Wynn-Williams, D. D.; Newton, E. M. G.; Edwards, H. G. M.

    Pigments are key potential biomarkers for any former life on Mars because of the selective pressure of solar radiation on any biological system that could have evolved at its surface. We have found that the near -Infrared laser Raman spectrometer available to use was eminently suitable for diagnostic analysis of pigments because of their minimal autofluorescence at its 1064 nm excitation wav elength. However, we have now evaluated a diverse range of excitation wavelengths to confirm this choice, to ensure that we have the best technique to seek for pigments and their derivatives from any former surface life on Mars. The Raman is weak relative to fluorescence, which results in elevated baseline and concurrent swamping of Raman bands. We confirm the molecular information available from near-IR FT Raman spectra for two highly pigmented UV-tolerant epilithic Antarctic lichens (Acarospora chlorop hana and Caloplaca saxicola) from Victoria Land, a whole endolithic microbial community and endolithic cyanobacterium Chroococcidiopsis from within translucent sandstone of the Trans -Antarctic Mountains, and the free- living cyanobacterium Nostoc commune from Alexander Island, Antarctic Peninsula region. We also show that much of the information we require on biomolecules is not evident from lasers of shorter wavelengths. A miniature 1064 nm Raman spectrometer with an In-Ga-As detector sensitive to IR is being developed by Montana State University (now existing as a prototype) as the prime instrument for a proposed UK-led Mars rover mission (Vanguard). Preliminary spectra from this system confirm the suitability of the near-IR laser.

  1. Shorter epilepsy duration is associated with better seizure outcome in temporal lobe epilepsy surgery

    Directory of Open Access Journals (Sweden)

    Lucas Crociati Meguins

    2015-03-01

    Full Text Available Objective To investigate the influence of patient’s age and seizure onset on surgical outcome of temporal lobe epilepsy (TLE. Method A retrospective observational investigation performed from a cohort of patients from 2000 to 2012. Results A total of 229 patients were included. One-hundred and eleven of 179 patients (62% were classified as Engel I in the group with < 50 years old, whereas 33 of 50 (66% in the group with ≥ 50 years old group (p = 0.82. From those Engel I, 88 (61% reported epilepsy duration inferior to 10 years and 56 (39% superior to 10 years (p < 0.01. From the total of patients not seizure free, 36 (42% reported epilepsy duration inferior to 10 years and 49 (58% superior to 10 years (p < 0.01. Conclusion Patients with shorter duration of epilepsy before surgery had better postoperative seizure control than patients with longer duration of seizures.

  2. Shorter Decentralized Attribute-Based Encryption via Extended Dual System Groups

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2017-01-01

    Full Text Available Decentralized attribute-based encryption (ABE is a special form of multiauthority ABE systems, in which no central authority and global coordination are required other than creating the common reference parameters. In this paper, we propose a new decentralized ABE in prime-order groups by using extended dual system groups. We formulate some assumptions used to prove the security of our scheme. Our proposed scheme is fully secure under the standard k-Lin assumption in random oracle model and can support any monotone access structures. Compared with existing fully secure decentralized ABE systems, our construction has shorter ciphertexts and secret keys. Moreover, fast decryption is achieved in our system, in which ciphertexts can be decrypted with a constant number of pairings.

  3. Shorter preschool, leukocyte telomere length is associated with obesity at age 9 in Latino children

    DEFF Research Database (Denmark)

    Kjaer, Thora Wesenberg; Faurholt-Jepsen, D; Mehta, K M

    2018-01-01

    The aim of this study was to determine the potential role of leukocyte telomere length as a biomarker for development of childhood obesity in a low-income Latino population. A birth cohort of Latino children (N = 201) in San Francisco (recruited May 2006-May 2007) was followed until age 9...... and assessed annually for obesity and dietary intake. Leukocyte telomere length was measured at 4 and 5 years (n = 102) and assessed as a predictor for obesity at age 9, adjusting for known risk factors. Furthermore, leukocyte telomere length at age 4 and 5 was evaluated as a possible mediator...... of the relationship between excessive sugar-sweetened beverage consumption and obesity at age 9. Shorter leukocyte telomere length in preschoolers was associated with obesity at age 9 (adjusted odds ratio 0.35, 95% confidence interval 0.13-0.94) after adjustment for known risk factors. Telomere length mediated 11...

  4. Hereditary angioedema attacks resolve faster and are shorter after early icatibant treatment.

    Directory of Open Access Journals (Sweden)

    Marcus Maurer

    Full Text Available BACKGROUND: Attacks of hereditary angioedema (HAE are unpredictable and, if affecting the upper airway, can be lethal. Icatibant is used for physician- or patient self-administered symptomatic treatment of HAE attacks in adults. Its mode of action includes disruption of the bradykinin pathway via blockade of the bradykinin B(2 receptor. Early treatment is believed to shorten attack duration and prevent severe outcomes; however, evidence to support these benefits is lacking. OBJECTIVE: To examine the impact of timing of icatibant administration on the duration and resolution of HAE type I and II attacks. METHODS: The Icatibant Outcome Survey is an international, prospective, observational study for patients treated with icatibant. Data on timings and outcomes of icatibant treatment for HAE attacks were collected between July 2009-February 2012. A mixed-model of repeated measures was performed for 426 attacks in 136 HAE type I and II patients. RESULTS: Attack duration was significantly shorter in patients treated <1 hour of attack onset compared with those treated ≥ 1 hour (6.1 hours versus 16.8 hours [p<0.001]. Similar significant effects were observed for <2 hours versus ≥ 2 hours (7.2 hours versus 20.2 hours [p<0.001] and <5 hours versus ≥ 5 hours (8.0 hours versus 23.5 hours [p<0.001]. Treatment within 1 hour of attack onset also significantly reduced time to attack resolution (5.8 hours versus 8.8 hours [p<0.05]. Self-administrators were more likely to treat early and experience shorter attacks than those treated by a healthcare professional. CONCLUSION: Early blockade of the bradykinin B(2 receptor with icatibant, particularly within the first hour of attack onset, significantly reduced attack duration and time to attack resolution.

  5. ATM/RB1 mutations predict shorter overall survival in urothelial cancer.

    Science.gov (United States)

    Yin, Ming; Grivas, Petros; Emamekhoo, Hamid; Mendiratta, Prateek; Ali, Siraj; Hsu, JoAnn; Vasekar, Monali; Drabick, Joseph J; Pal, Sumanta; Joshi, Monika

    2018-03-30

    Mutations of DNA repair genes, e.g. ATM/RB1 , are frequently found in urothelial cancer (UC) and have been associated with better response to cisplatin-based chemotherapy. Further external validation of the prognostic value of ATM/RB1 mutations in UC can inform clinical decision making and trial designs. In the discovery dataset, ATM/RB1 mutations were present in 24% of patients and were associated with shorter OS (adjusted HR 2.67, 95% CI, 1.45-4.92, p = 0.002). There was a higher mutation load in patients carrying ATM/RB1 mutations (median mutation load: 6.7 versus 5.5 per Mb, p = 0.072). In the validation dataset, ATM/RB1 mutations were present in 22.2% of patients and were non-significantly associated with shorter OS (adjusted HR 1.87, 95% CI, 0.97-3.59, p = 0.06) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, p = 0.126). Exome sequencing data of 130 bladder UC patients from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM/RB1 mutations. Results were validated in an independent cohort of 81 advanced UC patients. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI) to compare overall survival (OS). ATM/RB1 mutations may be a biomarker of poor prognosis in unselected UC patients and may correlate with higher mutational load. Further studies are required to determine factors that can further stratify prognosis and evaluate predictive role of ATM/RB1 mutation status to immunotherapy and platinum-based chemotherapy.

  6. Marital disruption is associated with shorter salivary telomere length in a probability sample of older adults.

    Science.gov (United States)

    Whisman, Mark A; Robustelli, Briana L; Sbarra, David A

    2016-05-01

    Marital disruption (i.e., marital separation, divorce) is associated with a wide range of poor mental and physical health outcomes, including increased risk for all-cause mortality. One biological intermediary that may help explain the association between marital disruption and poor health is accelerated cellular aging. This study examines the association between marital disruption and salivary telomere length in a United States probability sample of adults ≥50 years of age. Participants were 3526 individuals who participated in the 2008 wave of the Health and Retirement Study. Telomere length assays were performed using quantitative real-time polymerase chain reaction (qPCR) on DNA extracted from saliva samples. Health and lifestyle factors, traumatic and stressful life events, and neuroticism were assessed via self-report. Linear regression analyses were conducted to examine the associations between predictor variables and salivary telomere length. Based on their marital status data in the 2006 wave, people who were separated or divorced had shorter salivary telomeres than people who were continuously married or had never been married, and the association between marital disruption and salivary telomere length was not moderated by gender or neuroticism. Furthermore, the association between marital disruption and salivary telomere length remained statistically significant after adjusting for demographic and socioeconomic variables, neuroticism, cigarette use, body mass, traumatic life events, and other stressful life events. Additionally, results revealed that currently married adults with a history of divorce evidenced shorter salivary telomeres than people who were continuously married or never married. Accelerated cellular aging, as indexed by telomere shortening, may be one pathway through which marital disruption is associated with morbidity and mortality. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. A shorter and more specific oral sensitization-based experimental model of food allergy in mice.

    Science.gov (United States)

    Bailón, Elvira; Cueto-Sola, Margarita; Utrilla, Pilar; Rodríguez-Ruiz, Judith; Garrido-Mesa, Natividad; Zarzuelo, Antonio; Xaus, Jordi; Gálvez, Julio; Comalada, Mònica

    2012-07-31

    Cow's milk protein allergy (CMPA) is one of the most prevalent human food-borne allergies, particularly in children. Experimental animal models have become critical tools with which to perform research on new therapeutic approaches and on the molecular mechanisms involved. However, oral food allergen sensitization in mice requires several weeks and is usually associated with unspecific immune responses. To overcome these inconveniences, we have developed a new food allergy model that takes only two weeks while retaining the main characters of allergic response to food antigens. The new model is characterized by oral sensitization of weaned Balb/c mice with 5 doses of purified cow's milk protein (CMP) plus cholera toxin (CT) for only two weeks and posterior challenge with an intraperitoneal administration of the allergen at the end of the sensitization period. In parallel, we studied a conventional protocol that lasts for seven weeks, and also the non-specific effects exerted by CT in both protocols. The shorter protocol achieves a similar clinical score as the original food allergy model without macroscopically affecting gut morphology or physiology. Moreover, the shorter protocol caused an increased IL-4 production and a more selective antigen-specific IgG1 response. Finally, the extended CT administration during the sensitization period of the conventional protocol is responsible for the exacerbated immune response observed in that model. Therefore, the new model presented here allows a reduction not only in experimental time but also in the number of animals required per experiment while maintaining the features of conventional allergy models. We propose that the new protocol reported will contribute to advancing allergy research. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Solar Observations at Submillimeter Wavelengths

    Science.gov (United States)

    Kaufmann, P.

    We review earlier to recent observational evidences and theoretical motivations leading to a renewed interest to observe flares in the submillimeter (submm) - infrared (IR) range of wavelengths. We describe the new solar dedicated submillimeter wave telescope which began operations at El Leoncito in the Argentina Andes: the SST project. It consists of focal plane arrays of two 405 GHz and four 212 GHz radiometers placed in a 1.5-m radome-enclosed Cassegrain antenna, operating simultaneously with one millisecond time resolution. The first solar events analyzed exhibited the onset of rapid submm-wave spikes (100-300 ms), well associated to other flare manifestations, especially at X-rays. The spikes positions were found scattered over the flaring source by tens of arcseconds. For one event an excellent association was found between the gamma-ray emission time profile and the rate of occurrence of submm-wave rapid spikes. The preliminary results favour the idea that bulk burst emissions are a response to numerous fast energetic injections, discrete in time, produced at different spatial positions over the flaring region. Coronal mass ejections were associated to the events studied. Their trajectories extrapolated to the solar surface appear to correspond to the onset time of the submm-wave spikes, which might represent an early signature of the CME's initial acceleration process.

  9. Optical slotted circuit switched network: a bandwidth efficient alternative to wavelength-routed network

    Science.gov (United States)

    Li, Yan; Collier, Martin

    2007-11-01

    Wavelength-routed networks have received enormous attention due to the fact that they are relatively simple to implement and implicitly offer Quality of Service (QoS) guarantees. However, they suffer from a bandwidth inefficiency problem and require complex Routing and Wavelength Assignment (RWA). Most attempts to address the above issues exploit the joint use of WDM and TDM technologies. The resultant TDM-based wavelength-routed networks partition the wavelength bandwidth into fixed-length time slots organized as a fixed-length frame. Multiple connections can thus time-share a wavelength and the grooming of their traffic leads to better bandwidth utilization. The capability of switching in both wavelength and time domains in such networks also mitigates the RWA problem. However, TMD-based wavelength-routed networks work in synchronous mode and strict synchronization among all network nodes is required. Global synchronization for all-optical networks which operate at extremely high speed is technically challenging, and deploying an optical synchronizer for each wavelength involves considerable cost. An Optical Slotted Circuit Switching (OSCS) architecture is proposed in this paper. In an OSCS network, slotted circuits are created to better utilize the wavelength bandwidth than in classic wavelength-routed networks. The operation of the protocol is such as to avoid the need for global synchronization required by TDM-based wavelength-routed networks.

  10. Risky family processes prospectively forecast shorter telomere length mediated through negative emotions.

    Science.gov (United States)

    Brody, Gene H; Yu, Tianyi; Shalev, Idan

    2017-05-01

    This study was designed to examine prospective associations of risky family environments with subsequent levels of negative emotions and peripheral blood mononuclear cell telomere length (TL), a marker of cellular aging. A second purpose was to determine whether negative emotions mediate the hypothesized link between risky family processes and diminished telomere length. Participants were 293 adolescents (age 17 years at the first assessment) and their primary caregivers. Caregivers provided data on risky family processes when the youths were age 17 years, youths reported their negative emotions at age 18 years, and youths' TL was assayed from a blood sample at age 22 years. The results revealed that (a) risky family processes forecast heightened negative emotions (β = .316, p emotions forecast shorter TL (β = -.187, p = .012), and (c) negative emotions served as a mediator connecting risky family processes with diminished TL (indirect effect = -0.012, 95% CI [-0.036, -0.002]). These findings are consistent with the hypothesis that risky family processes presage premature cellular aging through effects on negative emotions, with potential implications for lifelong health. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  11. Gain of chromosome arm 1q in atypical meningioma correlates with shorter progression-free survival.

    LENUS (Irish Health Repository)

    2012-02-01

    Aims: Atypical (WHO grade II) meningiomas have moderately high recurrence rates; even for completely resected tumours, approximately one-third will recur. Post-operative radiotherapy (RT) may aid local control and improve survival, but carries the risk of side effects. More accurate prediction of recurrence risk is therefore needed for patients with atypical meningioma. Previously, we used high-resolution array CGH to identify genetic variations in 47 primary atypical meningiomas and found that approximately 60% of tumors show gain of 1q at 1q25.1 and 1q25.3 to 1q32.1 and that 1q gain appeared to correlate with shorter progression-free survival. This study aimed to validate and extend these findings in an independent sample. Methods: 86 completely resected atypical meningiomas (with 25 recurrences) from two neurosurgical centres in Ireland were identified and clinical follow up was obtained. Utilizing a dual-colour interphase FISH assay, 1q gain was assessed using BAC probes directed against 1q25.1 and 1q32.1. Results: The results confirm the high prevalence of 1q gain at these loci in atypical meningiomas. We further show that gain at 1q32.1 and age each correlate with progression-free survival in patients who have undergone complete surgical resection of atypical meningiomas. Conclusions: These independent findings suggest that assessment of 1q copy number status can add clinically useful information for the management of patients with atypical meningiomas.

  12. Greater reproductive investment, but shorter lifespan, in agrosystem than in natural-habitat toads

    Directory of Open Access Journals (Sweden)

    Francisco Javier Zamora-Camacho

    2017-09-01

    Full Text Available Global amphibian decline is due to several factors: habitat loss, anthropization, pollution, emerging diseases, and global warming. Amphibians, with complex life cycles, are particularly susceptible to habitat alterations, and their survival may be impaired in anthropized habitats. Increased mortality is a well-known consequence of anthropization. Life-history theory predicts higher reproductive investment when mortality is increased. In this work, we compared age, body size, and different indicators of reproductive investment, as well as prey availability, in natterjack toads (Epidalea calamita from agrosystems and adjacent natural pine groves in Southwestern Spain. Mean age was lower in agrosystems than in pine groves, possibly as a consequence of increased mortality due to agrosystem environmental stressors. Remarkably, agrosystem toads were larger despite being younger, suggesting accelerated growth rate. Although we detected no differences in prey availability between habitats, artificial irrigation could shorten aestivation in agrosystems, thus increasing energy trade. Moreover, agrosystem toads exhibited increased indicators of reproductive investment. In the light of life-history theory, agrosystem toads might compensate for lesser reproductive events—due to shorter lives—with a higher reproductive investment in each attempt. Our results show that agrosystems may alter demography, which may have complex consequences on both individual fitness and population stability.

  13. Long-wavelength microinstabilities in toroidal plasmas

    International Nuclear Information System (INIS)

    Tang, W.M.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Res. (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 29] L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

  14. Multi-Wavelength Photomagnetic Imaging for Oral Cancer

    Science.gov (United States)

    Marks, Michael

    In this study, a multi-wavelength Photomagnetic Imaging (PMI) system is developed and evaluated with experimental studies.. PMI measures temperature increases in samples illuminated by near-infrared light sources using magnetic resonance thermometry. A multiphysics solver combining light and heat transfer models the spatiotemporal distribution of the temperature change. The PMI system develop in this work uses three lasers of varying wavelength (785 nm, 808 nm, 860 nm) to heat the sample. By using multiple wavelengths, we enable the PMI system to quantify the relative concentrations of optical contrast in turbid media and monitor their distribution, at a higher resolution than conventional diffuse optical imaging. The data collected from agarose phantoms with multiple embedded contrast agents designed to simulate the optical properties of oxy- and deoxy-hemoglobin is presented. The reconstructed images demonstrate that multi-wavelength PMI can resolve this complex inclusion structure with high resolution and recover the concentration of each contrast agent with high quantitative accuracy. The modified multi-wavelength PMI system operates under the maximum skin exposure limits defined by the American National Standards Institute, to enable future clinical applications.

  15. Study of the correlation of scintillation decay and emission wavelength

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Yamaji, Akihiro; Kawaguchi, Noriaki; Kamada, Kei; Totsuka, Daisuke; Fukuda, Kentaro; Yamanoi, Kohei; Nishi, Ryosuke; Kurosawa, Shunsuke; Shimizu, Toshihiko; Sarukura, Nobuhiko

    2013-01-01

    In photoluminescence which directly excites the emission center of phosphor material is known to have a correlation between the emission wavelength and the decay time based on quantum mechanics. In scintillation phenomenon, host lattice of the material is first excited by ionizing radiation and then the excitation energy is transferred to emission centers. For the first time, we investigated the correlation between the scintillation decay and the emission wavelength by using pulse X-ray equipped streak camera system which could observe time and wavelength resolved scintillation phenomenon. Investigated materials were Ce 3+ , Pr 3+ and Nd 3+ doped oxides and fluorides which all showed 5d-4f transition based emission. As a result, we obtained the relation that τ (scintillation decay time) was proportional to the λ 2.15 (emission wavelength). -- Highlights: ► The correlation between emission wavelength and scintillation decay time is investigated. ► Photoluminescence decay times are also evaluated and compared with scintillation decay times. ► It is proved the relaxation process in emission center is dominant even in scintillation decay

  16. The Effect of Shorter Treatment Regimens for Hepatitis C on Population Health and Under Fixed Budgets.

    Science.gov (United States)

    Morgan, Jake R; Kim, Arthur Y; Naggie, Susanna; Linas, Benjamin P

    2018-01-01

    Direct acting antiviral hepatitis C virus (HCV) therapies are highly effective but costly. Wider adoption of an 8-week ledipasvir/sofosbuvir treatment regimen could result in significant savings, but may be less efficacious compared with a 12-week regimen. We evaluated outcomes under a constrained budget and cost-effectiveness of 8 vs 12 weeks of therapy in treatment-naïve, noncirrhotic, genotype 1 HCV-infected black and nonblack individuals and considered scenarios of IL28B and NS5A resistance testing to determine treatment duration in sensitivity analyses. We developed a decision tree to use in conjunction with Monte Carlo simulation to investigate the cost-effectiveness of recommended treatment durations and the population health effect of these strategies given a constrained budget. Outcomes included the total number of individuals treated and attaining sustained virologic response (SVR) given a constrained budget and incremental cost-effectiveness ratios. We found that treating eligible (treatment-naïve, noncirrhotic, HCV-RNA budget among both black and nonblack individuals, and our results suggested that NS5A resistance testing is cost-effective. Eight-week therapy provides good value, and wider adoption of shorter treatment could allow more individuals to attain SVR on the population level given a constrained budget. This analysis provides an evidence base to justify movement of the 8-week regimen to the preferred regimen list for appropriate patients in the HCV treatment guidelines and suggests expanding that recommendation to black patients in settings where cost and relapse trade-offs are considered.

  17. MO-E-BRD-02: Accelerated Partial Breast Irradiation in Brachytherapy: Is Shorter Better?

    International Nuclear Information System (INIS)

    Todor, D.

    2015-01-01

    Is Non-invasive Image-Guided Breast Brachytherapy Good? – Jess Hiatt, MS Non-invasive Image-Guided Breast Brachytherapy (NIBB) is an emerging therapy for breast boost treatments as well as Accelerated Partial Breast Irradiation (APBI) using HDR surface breast brachytherapy. NIBB allows for smaller treatment volumes while maintaining optimal target coverage. Considering the real-time image-guidance and immobilization provided by the NIBB modality, minimal margins around the target tissue are necessary. Accelerated Partial Breast Irradiation in brachytherapy: is shorter better? - Dorin Todor, PhD VCU A review of balloon and strut devices will be provided together with the origins of APBI: the interstitial multi-catheter implant. A dosimetric and radiobiological perspective will help point out the evolution in breast brachytherapy, both in terms of devices and the protocols/clinical trials under which these devices are used. Improvements in imaging, delivery modalities and convenience are among the factors driving the ultrashort fractionation schedules but our understanding of both local control and toxicities associated with various treatments is lagging. A comparison between various schedules, from a radiobiological perspective, will be given together with a critical analysis of the issues. to review and understand the evolution and development of APBI using brachytherapy methods to understand the basis and limitations of radio-biological ‘equivalence’ between fractionation schedules to review commonly used and proposed fractionation schedules Intra-operative breast brachytherapy: Is one stop shopping best?- Bruce Libby, PhD. University of Virginia A review of intraoperative breast brachytherapy will be presented, including the Targit-A and other trials that have used electronic brachytherapy. More modern approaches, in which the lumpectomy procedure is integrated into an APBI workflow, will also be discussed. Learning Objectives: To review past and current

  18. Shorter Ground Contact Time and Better Running Economy: Evidence From Female Kenyan Runners.

    Science.gov (United States)

    Mooses, Martin; Haile, Diresibachew W; Ojiambo, Robert; Sang, Meshack; Mooses, Kerli; Lane, Amy R; Hackney, Anthony C

    2018-06-25

    Mooses, M, Haile, DW, Ojiambo, R, Sang, M, Mooses, K, Lane, AR, and Hackney, AC. Shorter ground contact time and better running economy: evidence from female Kenyan runners. J Strength Cond Res XX(X): 000-000, 2018-Previously, it has been concluded that the improvement in running economy (RE) might be considered as a key to the continued improvement in performance when no further increase in V[Combining Dot Above]O2max is observed. To date, RE has been extensively studied among male East African distance runners. By contrast, there is a paucity of data on the RE of female East African runners. A total of 10 female Kenyan runners performed 3 × 1,600-m steady-state run trials on a flat outdoor clay track (400-m lap) at the intensities that corresponded to their everyday training intensities for easy, moderate, and fast running. Running economy together with gait characteristics was determined. Participants showed moderate to very good RE at the first (202 ± 26 ml·kg·km) and second (188 ± 12 ml·kg·km) run trials, respectively. Correlation analysis revealed significant relationship between ground contact time (GCT) and RE at the second run (r = 0.782; p = 0.022), which represented the intensity of anaerobic threshold. This study is the first to report the RE and gait characteristics of East African female athletes measured under everyday training settings. We provided the evidence that GCT is associated with the superior RE of the female Kenyan runners.

  19. MO-E-BRD-02: Accelerated Partial Breast Irradiation in Brachytherapy: Is Shorter Better?

    Energy Technology Data Exchange (ETDEWEB)

    Todor, D. [Virginia Commonwealth University (United States)

    2015-06-15

    Is Non-invasive Image-Guided Breast Brachytherapy Good? – Jess Hiatt, MS Non-invasive Image-Guided Breast Brachytherapy (NIBB) is an emerging therapy for breast boost treatments as well as Accelerated Partial Breast Irradiation (APBI) using HDR surface breast brachytherapy. NIBB allows for smaller treatment volumes while maintaining optimal target coverage. Considering the real-time image-guidance and immobilization provided by the NIBB modality, minimal margins around the target tissue are necessary. Accelerated Partial Breast Irradiation in brachytherapy: is shorter better? - Dorin Todor, PhD VCU A review of balloon and strut devices will be provided together with the origins of APBI: the interstitial multi-catheter implant. A dosimetric and radiobiological perspective will help point out the evolution in breast brachytherapy, both in terms of devices and the protocols/clinical trials under which these devices are used. Improvements in imaging, delivery modalities and convenience are among the factors driving the ultrashort fractionation schedules but our understanding of both local control and toxicities associated with various treatments is lagging. A comparison between various schedules, from a radiobiological perspective, will be given together with a critical analysis of the issues. to review and understand the evolution and development of APBI using brachytherapy methods to understand the basis and limitations of radio-biological ‘equivalence’ between fractionation schedules to review commonly used and proposed fractionation schedules Intra-operative breast brachytherapy: Is one stop shopping best?- Bruce Libby, PhD. University of Virginia A review of intraoperative breast brachytherapy will be presented, including the Targit-A and other trials that have used electronic brachytherapy. More modern approaches, in which the lumpectomy procedure is integrated into an APBI workflow, will also be discussed. Learning Objectives: To review past and current

  20. Are Shorter Article Titles More Attractive for Citations? Cross-sectional Study of 22 Scientific Journals

    Science.gov (United States)

    Habibzadeh, Farrokh; Yadollahie, Mahboobeh

    2010-01-01

    Aim To investigate the correlation between the length of the title of a scientific article and the number of citations it receives, in view of the common editorial call for shorter titles. Methods Title and the number of citations to all articles published in 2005 in 22 arbitrarily chosen English-language journals (n = 9031) were retrieved from citation database Scopus. The 2008 journal impact factors of these 22 journals were also retrieved from Thomson Reuters’ Journal Citation Report (JCR). Assuming the article title length as the independent variable, and the number of citations to the article as the dependent variable, a linear regression model was applied. Results The slope of the regression line for some journals (n = 6, when titles were measured in characters but 7 when titles were measured in words) was negative – none was significantly different from 0. The overall slope for all journals was 0.140 (when titles were measured in characters) and 0.778 (when titles were measured in words), significantly different from 0 (P articles with longer titles received more citations – Spearman ρ = 0.266 – when titles were measured in characters, and ρ = 0.244 when titles were measured in words (P 10 and for 2 out of 14 journals with impact factor <10 (P < 0.001, Fisher exact test). Conclusion Longer titles seem to be associated with higher citation rates. This association is more pronounced for journals with high impact factors. Editors who insist on brief and concise titles should perhaps update the guidelines for authors of their journals and have more flexibility regarding the length of the title. PMID:20401960

  1. Shorter exposures to harder X-rays trigger early apoptotic events in Xenopus laevis embryos.

    Directory of Open Access Journals (Sweden)

    JiaJia Dong

    Full Text Available BACKGROUND: A long-standing conventional view of radiation-induced apoptosis is that increased exposure results in augmented apoptosis in a biological system, with a threshold below which radiation doses do not cause any significant increase in cell death. The consequences of this belief impact the extent to which malignant diseases and non-malignant conditions are therapeutically treated and how radiation is used in combination with other therapies. Our research challenges the current dogma of dose-dependent induction of apoptosis and establishes a new parallel paradigm to the photoelectric effect in biological systems. METHODOLOGY/PRINCIPAL FINDINGS: We explored how the energy of individual X-ray photons and exposure time, both factors that determine the total dose, influence the occurrence of cell death in early Xenopus embryo. Three different experimental scenarios were analyzed and morphological and biochemical hallmarks of apoptosis were evaluated. Initially, we examined cell death events in embryos exposed to increasing incident energies when the exposure time was preset. Then, we evaluated the embryo's response when the exposure time was augmented while the energy value remained constant. Lastly, we studied the incidence of apoptosis in embryos exposed to an equal total dose of radiation that resulted from increasing the incoming energy while lowering the exposure time. CONCLUSIONS/SIGNIFICANCE: Overall, our data establish that the energy of the incident photon is a major contributor to the outcome of the biological system. In particular, for embryos exposed under identical conditions and delivered the same absorbed dose of radiation, the response is significantly increased when shorter bursts of more energetic photons are used. These results suggest that biological organisms display properties similar to the photoelectric effect in physical systems and provide new insights into how radiation-mediated apoptosis should be understood and

  2. Access to Electric Light Is Associated with Shorter Sleep Duration in a Traditionally Hunter-Gatherer Community.

    Science.gov (United States)

    de la Iglesia, Horacio O; Fernández-Duque, Eduardo; Golombek, Diego A; Lanza, Norberto; Duffy, Jeanne F; Czeisler, Charles A; Valeggia, Claudia R

    2015-08-01

    Access to electric light might have shifted the ancestral timing and duration of human sleep. To test this hypothesis, we studied two communities of the historically hunter-gatherer indigenous Toba/Qom in the Argentinean Chaco. These communities share the same ethnic and sociocultural background, but one has free access to electricity while the other relies exclusively on natural light. We fitted participants in each community with wrist activity data loggers to assess their sleep-wake cycles during one week in the summer and one week in the winter. During the summer, participants with access to electricity had a tendency to a shorter daily sleep bout (43 ± 21 min) than those living under natural light conditions. This difference was due to a later daily bedtime and sleep onset in the community with electricity, but a similar sleep offset and rise time in both communities. In the winter, participants without access to electricity slept longer (56 ± 17 min) than those with access to electricity, and this was also related to earlier bedtimes and sleep onsets than participants in the community with electricity. In both communities, daily sleep duration was longer during the winter than during the summer. Our field study supports the notion that access to inexpensive sources of artificial light and the ability to create artificially lit environments must have been key factors in reducing sleep in industrialized human societies. © 2015 The Author(s).

  3. Shorter Hospital Stays and Lower Costs for Rivaroxaban Compared With Warfarin for Venous Thrombosis Admissions.

    Science.gov (United States)

    Margolis, Jay M; Deitelzweig, Steven; Kline, Jeffrey; Tran, Oth; Smith, David M; Bookhart, Brahim; Crivera, Concetta; Schein, Jeff

    2016-10-06

    % confidence interval, $8035-$8739]; warfarin $10 275 [95% confidence interval, $9842-$10 708]). Rivaroxaban was associated with significantly shorter hospital LOS and lower hospitalization costs compared with warfarin. © 2016 The Authors, Janssen Scientific Affairs, LLC, and Truven Health Analytics. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  4. Pulmonary Embolism Inpatients Treated With Rivaroxaban Had Shorter Hospital Stays and Lower Costs Compared With Warfarin.

    Science.gov (United States)

    Margolis, Jay M; Deitelzweig, Steven; Kline, Jeffrey; Tran, Oth; Smith, David M; Crivera, Concetta; Bookhart, Brahim; Schein, Jeff

    2016-11-01

    Using real-world data, this study compares inpatient length of stay (LOS) and costs for patients with a primary diagnosis of pulmonary embolism (PE) initiating treatment with oral anticoagulation with rivaroxaban versus warfarin. Hospitalizations from MarketScan's Hospital Drug Database were selected from November 1, 2012, through December 31, 2013, for adults with a primary diagnosis of PE initiating treatment with rivaroxaban or warfarin. Warfarin patients were matched 1:1 to rivaroxaban patients using exact and propensity score matching. Hospital LOS, treatment patterns, and hospitalization costs were evaluated. Matched cohorts included 751 rivaroxaban-treated patients and 751 warfarin-treated patients. Adjusted mean LOS was 3.77 days for rivaroxaban patients (95% CI, 3.66-3.87 days) and 5.48 days for warfarin patients (95% CI, 5.33-5.63 days; P < .001). Mean (SD) LOS was shorter for patients taking rivaroxaban whether admission was for provoked PE (rivaroxaban: 5.2 [5.1] days; warfarin: 7.0 [6.5] days; P < .001) or unprovoked PE (rivaroxaban: 3.4 [2.3] days; warfarin: 5.1 [2.7] days; P < .001). Mean (SD) days from first dose to discharge were 2.5 (1.7) (rivaroxaban) and 4.0 (2.9) (warfarin) when initiated with parenteral anticoagulants (P < .001) and 2.7 (1.7) (rivaroxaban) and 4.0 (2.2) (warfarin) without parenteral anticoagulants (P < .001). The rivaroxaban cohort incurred significantly lower unadjusted mean (SD) hospitalization costs (rivaroxaban: $8473 [$9105]; warfarin: $10,291 [$9185]; P < .001), confirmed by covariate adjustment with generalized linear modeling estimating predicted mean hospitalization costs of $8266 for rivaroxaban patients (95% CI, $7851-$8681) and $10,511 for warfarin patients (95% CI, $10,031-$10,992; P < .001). patients with PE treated with rivaroxaban incurred significantly lower hospitalization costs by $2245 per admission compared with patients treated with warfarin, which was attributable to cost offsets from 1.71 fewer days of

  5. Experimental studies on the production and suppression mechanism of the hot electrons produced by short wavelength laser

    International Nuclear Information System (INIS)

    Qi Lanying; Jiang Xiaohua; Zhao Xuewei; Li Sanwei; Zhang Wenhai; Li Chaoguang; Zheng Zhijian; Ding Yongkun

    1999-12-01

    The experiments on gold-disk and hohlraum and plastic hydrocarbon (CH) film targets irradiated by laser beams with wavelength 0.35 μm (Xingguang-II) and 0.53 μm (Shenguang-I) are performed. The characteristics of hot electrons are commonly deduced from spectrum of hard X-ray. Associated with the measurement of backward SRS and 3/2ω 0 , the production mechanism of hot electrons for different target type is analyzed in laser plasma with shorter wavelength. A effective way to suppress hot electrons has been found

  6. Multi-wavelength lasers using AWGs

    NARCIS (Netherlands)

    Besten, den J.H.

    2003-01-01

    Multiwavelength lasers using AWGs can be used as digitally tunable lasers with simple channel selection, and for generating multiple wavelengths simultanously. In this paper a number of different configurations is reviewed.

  7. Investigation of Alien Wavelength Quality in Live Multi-Domain, Multi-Vendor Link Using Advanced Simulation Tool

    DEFF Research Database (Denmark)

    Petersen, Martin Nordal; Nuijts, Roeland; Bjorn, Lars Lange

    2014-01-01

    This article presents an advanced optical model for simulation of alien wavelengths in multi-domain and multi-vendor dense wavelength-division multiplexing networks. The model aids optical network planners with a better understanding of the non-linear effects present in dense wavelength-division ......This article presents an advanced optical model for simulation of alien wavelengths in multi-domain and multi-vendor dense wavelength-division multiplexing networks. The model aids optical network planners with a better understanding of the non-linear effects present in dense wavelength......-division multiplexing systems and better utilization of alien wavelengths in future applications. The limiting physical effects for alien wavelengths are investigated in relation to power levels, channel spacing, and other factors. The simulation results are verified through experimental setup in live multi...

  8. Wavelength mismatch effect in electromagnetically induced absorption

    Energy Technology Data Exchange (ETDEWEB)

    Bharti, Vineet [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Wasan, Ajay [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Natarajan, Vasant [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2016-07-15

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  9. Wavelength mismatch effect in electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Bharti, Vineet; Wasan, Ajay; Natarajan, Vasant

    2016-01-01

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  10. Wavelength dependent measurement of extinction in an extended-face crystal of zinc selenide

    International Nuclear Information System (INIS)

    Stevenson, A.W.; Barnea, Z.

    1982-01-01

    The effect of extinction on Bijvoet ratios is demonstrated. It is suggested that an observed anomaly in the wavelength dependence of ZnSe Bijvoet ratios is due to the Borrmann effect. It is shown that wavelength dependent studies of extinction may be used to obtain extinction parameters from relative intensity measurements without resorting to a refined scale factor

  11. Mode-locked Ti:sapphire laser oscillators pumped by wavelength-multiplexed laser diodes

    Science.gov (United States)

    Sugiyama, Naoto; Tanaka, Hiroki; Kannari, Fumihiko

    2018-05-01

    We directly pumped a Ti:sapphire laser by combining 478 and 520 nm laser diodes to prevent the effect of absorption loss induced by the pump laser of shorter wavelengths (∼450 nm). We obtain a continuous-wave output power of 660 mW at a total incident pump power of 3.15 W. We demonstrate mode locking using a semiconductor saturable absorber mirror, and 126 fs pulses were obtained at a repetition rate of 192 MHz. At the maximum pump power, the average output power is 315 mW. Shorter mode-locked pulses of 42 and 48 fs were respectively achieved by Kerr-lens mode locking with average output powers of 280 and 360 mW at a repetition rate of 117 MHz.

  12. Introduction: a short-wavelength-FEL/storage-ring complex

    International Nuclear Information System (INIS)

    Sessler, A.M.

    1984-01-01

    We believe that, in view of the present state of FEL understanding, it is now proper to construct a research facility devoted to the use of coherent radiation and the advancement of FEL physics technology at wavelengths shorter than 1000 A. We show a possible layout of such a facility, which will be referred to as a Coherent xuv Facility (CXF), where research can be conducted on several techniques for generating coherent radiation. Undulators are already well understood and will generate broadly tunable, spatially coherent radiation of bandwidth lambda /Δlambda approx. = 10 2 . A crossed undulator system will extend the undulator capability to include variable polarization. For full coherence, in spatial as well as in longitudinal directions, it is necessary to induce and exploit density modulation in electron beams, as is the case in the transverse optical klystrons (TOKs) and FELs. In TOKs, coherent radiation is generated at harmonics of an input laser frequency, with the electron beam playing the role of a nonlinear medium. Ultimately, FELS would deliver intense, tunable x rays and vuv radiation of extremely narrow spectral width. There are two possible routes to an FEL, one based on feedback by end mirrors, the other based on development of a high-gain, single-pass device. It can be seen, from this paper, that the photon flux increases monotonically, or the wavelength decreases monotonically, as one goes through (1) undulator radiation, (2) TOK radiation, (3) FEL oscillator radiation, to (4) FEL single-pass radiation. Each of these will demand considerable quality development effort. Each will result in photon fluxes of increased value to the users

  13. The role of romantic attraction and conflict resolution in predicting shorter and longer relationship maintenance among adolescents.

    Science.gov (United States)

    Appel, Israel; Shulman, Shmuel

    2015-04-01

    This study examined the role of romantic attraction and conflict resolution patterns in shorter and longer relationship maintenance among adolescent couples. Data were used from 55 couples aged 15-18 years. Partners completed the Romantic Attraction scale and were observed negotiating a disagreement. Three and 6 months later, they were asked to report whether they were still together. Findings indicated that partners' romantic attraction and the tendency to minimize disagreements during interaction predicted shorter relationship maintenance. In contrast, longer relationship maintenance was predicted by partners' capability to resolve conflicts constructively in a positive atmosphere. Findings are embedded and discussed within Fisher's (2004) evolutionary theory of love.

  14. Investigations of model polymers: Dynamics of melts and statics of a long chain in a dilute melt of shorter chains

    International Nuclear Information System (INIS)

    Bishop, M.; Ceperley, D.; Frisch, H.L.; Kalos, M.H.

    1982-01-01

    We report additional results on a simple model of polymers, namely the diffusion in concentrated polymer systems and the static properties of one long chain in a dilute melt of shorter chains. It is found, for the polymer sizes and time scales amenable to our computer calculations, that there is as yet no evidence for a ''reptation'' regime in a melt. There is some indication of reptation in the case of a single chain moving through fixed obstacles. No statistically significant effect of the change, from excluded volume behavior of the long chain to ideal behavior as the shorter chains grow, is observed

  15. CO ICE PHOTODESORPTION: A WAVELENGTH-DEPENDENT STUDY

    International Nuclear Information System (INIS)

    Fayolle, Edith C.; Linnartz, Harold; Bertin, Mathieu; Romanzin, Claire; Michaut, Xavier; Fillion, Jean-Hugues; Oeberg, Karin I.

    2011-01-01

    UV-induced photodesorption of ice is a non-thermal evaporation process that can explain the presence of cold molecular gas in a range of interstellar regions. Information on the average UV photodesorption yield of astrophysically important ices exists for broadband UV lamp experiments. UV fields around low-mass pre-main-sequence stars, around shocks and in many other astrophysical environments are however often dominated by discrete atomic and molecular emission lines. It is therefore crucial to consider the wavelength dependence of photodesorption yields and mechanisms. In this work, for the first time, the wavelength-dependent photodesorption of pure CO ice is explored between 90 and 170 nm. The experiments are performed under ultra high vacuum conditions using tunable synchrotron radiation. Ice photodesorption is simultaneously probed by infrared absorption spectroscopy in reflection mode of the ice and by quadrupole mass spectrometry of the gas phase. The experimental results for CO reveal a strong wavelength dependence directly linked to the vibronic transition strengths of CO ice, implying that photodesorption is induced by electronic transition (DIET). The observed dependence on the ice absorption spectra implies relatively low photodesorption yields at 121.6 nm (Lyα), where CO barely absorbs, compared to the high yields found at wavelengths coinciding with transitions into the first electronic state of CO (A 1 Π at 150 nm); the CO photodesorption rates depend strongly on the UV profiles encountered in different star formation environments.

  16. Feasibility of a shorter Goal Attainment Scaling method for a pediatric spasticity clinic - The 3-milestones GAS.

    Science.gov (United States)

    Krasny-Pacini, A; Pauly, F; Hiebel, J; Godon, S; Isner-Horobeti, M-E; Chevignard, M

    2017-07-01

    Goal Attainment Scaling (GAS) is a method for writing personalized evaluation scales to quantify progress toward defined goals. It is useful in rehabilitation but is hampered by the experience required to adequately "predict" the possible outcomes relating to a particular goal before treatment and the time needed to describe all 5 levels of the scale. Here we aimed to investigate the feasibility of using GAS in a clinical setting of a pediatric spasticity clinic with a shorter method, the "3-milestones" GAS (goal setting with 3 levels and goal rating with the classical 5 levels). Secondary aims were to (1) analyze the types of goals children's therapists set for botulinum toxin treatment and (2) compare the score distribution (and therefore the ability to predict outcome) by goal type. Therapists were trained in GAS writing and prepared GAS scales in the regional spasticity-management clinic they attended with their patients and families. The study included all GAS scales written during a 2-year period. GAS score distribution across the 5 GAS levels was examined to assess whether the therapist could reliably predict outcome and whether the 3-milestones GAS yielded similar distributions as the original GAS method. In total, 541 GAS scales were written and showed the expected score distribution. Most scales (55%) referred to movement quality goals and fewer (29%) to family goals and activity domains. The 3-milestones GAS method was feasible within the time constraints of the spasticity clinic and could be used by local therapists in cooperation with the hospital team. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. Conditional inactivation of TNFα-converting enzyme in chondrocytes results in an elongated growth plate and shorter long bones.

    Directory of Open Access Journals (Sweden)

    Kenta Saito

    Full Text Available TNFα-converting enzyme (TACE is a membrane-bound proteolytic enzyme with essential roles in the functional regulation of TNFα and epidermal growth factor receptor (EGFR ligands. Previous studies have demonstrated critical roles for TACE in vivo, including epidermal development, immune response, and pathological neoangiogenesis, among others. However, the potential contribution of TACE to skeletal development is still unclear. In the present study, we generated a Tace mutant mouse in which Tace is conditionally disrupted in chondrocytes under the control of the Col2a1 promoter. These mutant mice were fertile and viable but all exhibited long bones that were approximately 10% shorter compared to those of wild-type animals. Histological analyses revealed that Tace mutant mice exhibited a longer hypertrophic zone in the growth plate, and there were fewer osteoclasts at the chondro-osseous junction in the Tace mutant mice than in their wild-type littermates. Of note, we found an increase in osteoprotegerin transcripts and a reduction in Rankl and Mmp-13 transcripts in the TACE-deficient cartilage, indicating that dysregulation of these genes is causally related to the skeletal defects in the Tace mutant mice. Furthermore, we also found that phosphorylation of EGFR was significantly reduced in the cartilage tissue lacking TACE, and that suppression of EGFR signaling increases osteoprotegerin transcripts and reduces Rankl and Mmp-13 transcripts in primary chondrocytes. In accordance, chondrocyte-specific abrogation of Egfr in vivo resulted in skeletal defects nearly identical to those observed in the Tace mutant mice. Taken together, these data suggest that TACE-EGFR signaling in chondrocytes is involved in the turnover of the growth plate during postnatal development via the transcriptional regulation of osteoprotegerin, Rankl, and Mmp-13.

  18. A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

    Science.gov (United States)

    Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

    2017-08-01

    This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

  19. Cells, bilirubin and light: formation of bilirubin photoproducts and cellular damage at defined wavelengths

    International Nuclear Information System (INIS)

    Christensen, T.; Kinn, G.; Granli, T.; Amundsen, I.

    1994-01-01

    Cultured cells from one human and one murine cell line were treated with bilirubin and irradiated with visible light of different wavelengths, either from phototherapy lamps or from a Xenon/Mercury lamp equipped with a monochromator. Bilirubin bound to human serum albumin was also irradiated with light. After irradiation, the bilirubin and its photoisomers were extracted with High Pressure Liquid Chromatography. The formation of single strand breaks in the DNA of treated cells was studied using a fluorescence marker. Cytotoxicity in the mouse skin cell line was measured by loss of the ability to form visible colonies in vitro. Green light exposure favours the production of lumirubin, while blue light causes more DNA damage and cytotoxicity. Green light may be more efficient and safer than shorter wavelength exposure when treating jaundiced newborns with phototherapy. 27 refs., 6 figs

  20. Accelerator physics and radiometric properties of superconducting wavelength shifters

    International Nuclear Information System (INIS)

    Scheer, Michael

    2008-01-01

    Subject of this thesis is the operation of wave-length shifters at electron storage rings and their use in radiometry. The basic aspects of the radiometry, the technical requirements, the influence of wave-length shifters on the storage ring, and results of first measurements are presented for a device installed at BESSY. Most of the calculations are carried out by the program WAVE, which has been developed within this thesis. WAVE allows to calculate the synchrotron radiation spectra of wavelength shifters within an relative uncertainty of 1/100000. The properties of wave-length shifters in terms of accelerator physics as well as a generating function for symplectic tracking calculations can also be calculated by WAVE. The later was implemented in the tracking code BETA to investigate the influence of insertion devices on the dynamic aperture and emittance of the storage ring. These studies led to the concept of alternating low- and high-beta-sections at BESSY-II, which allow to operate superconducting insertion devices without a significant distortion of the magnetic optics. To investigate the experimental aspects of the radiometry at wave-length shifters, a program based on the Monte-Carlo-code GEANT4 has been developed. It allows to simulate the radiometrical measurements and the absorption properties of detectors. With the developed codes first radiometrical measurements by the PTB have been analysed. A comparison of measurements and calculations show a reasonable agreement with deviations of about five percent in the spectral range of 40-60 keV behind a 1-mm-Cu filter. A better agreement was found between 20 keV and 80 keV without Cu filter. In this case the measured data agreed within a systematic uncertainty of two percent with the results of the calculations. (orig.)

  1. Wavelength-Dependent Extinction and Grain Sizes in "Dippers"

    Science.gov (United States)

    Sitko, Michael; Russell, Ray W.; Long, Zachary; Bayyari, Ammar; Assani, Korash; Grady, Carol; Lisse, Carey Michael; Marengo, Massimo; Wisniewski, John

    2018-01-01

    We have examined inter-night variability of K2-discovered "Dippers" that are not close to being viewed edge-on (as determined from previously-reported ALMA images) using the SpeX spectrograph on NASA's Infrared Telescope facility (IRTF). The three objects observed were EPIC 203850058, EPIC 205151387, and EPIC 204638512 ( = 2MASS J16042165-2130284). Using the ratio of the fluxes from 0.7-2.4 microns between two successive nights, we find that in at least two cases, the extinction increased toward shorter wavelengths. In the case of EPIC 204638512, we find that the properties of the dust differ from that seen in the diffuse interstellar medium and denser molecular clouds. However, the grain properties needed to explain the extinction does resemble those used to model the disks of many young stellar objects. The best fit to the data on EPIC 204638512 includes grains at least 500 microns in size, but lacks grains smaller than 0.25 microns. Since EPIC 204638512 is seen nearly face-on, it is possible the grains are entrained in an accretion flow that preferentially destroys the smallest grains. However, we have no indication of significant gas accretion onto the star in the form of emission lines observed in young low-mass stars. But the He I line at 1.083 microns was seen to change from night to night, and showed a P Cygni profile on one night, suggesting the gas might be outflowing from regions near the star.

  2. Wear Fast, Die Young: More Worn Teeth and Shorter Lives in Iberian Compared to Scottish Red Deer.

    Science.gov (United States)

    Pérez-Barbería, F J; Carranza, J; Sánchez-Prieto, C

    2015-01-01

    Teeth in Cervidae are permanent structures that are not replaceable or repairable; consequently their rate of wear, due to the grinding effect of food and dental attrition, affects their duration and can determine an animal's lifespan. Tooth wear is also a useful indicator of accumulative life energy investment in intake and mastication and their interactions with diet. Little is known regarding how natural and sexual selection operate on dental structures within a species in contrasting environments and how these relate to life history traits to explain differences in population rates of tooth wear and longevity. We hypothesised that populations under harsh environmental conditions should be selected for more hypsodont teeth while sexual selection may maintain similar sex differences within different populations. We investigated the patterns of tooth wear in males and females of Iberian red deer (Cervus elaphus hispanicus) in Southern Spain and Scottish red deer (C. e. scoticus) across Scotland, that occur in very different environments, using 10343 samples from legal hunting activities. We found higher rates of both incisor and molar wear in the Spanish compared to Scottish populations. However, Scottish red deer had larger incisors at emergence than Iberian red deer, whilst molars emerged at a similar size in both populations and sexes. Iberian and Scottish males had earlier tooth depletion than females, in support of a similar sexual selection process in both populations. However, whilst average lifespan for Iberian males was 4 years shorter than that for Iberian females and Scottish males, Scottish males only showed a reduction of 1 year in average lifespan with respect to Scottish females. More worn molars were associated with larger mandibles in both populations, suggesting that higher intake and/or greater investment in food comminution may have favoured increased body growth, before later loss of tooth efficiency due to severe wear. These results

  3. Critical de Broglie wavelength in superconductors

    Science.gov (United States)

    Talantsev, E. F.

    2018-03-01

    There are growing numbers of experimental evidences that the self-field critical currents, Jc(sf,T), are a new instructive tool to investigate fundamental properties of superconductors ranging from atomically thin films [M. Liao et al., Nat. Phys. 6 (2018), https://doi.org/10.1038/s41567-017-0031-6; E. F. Talantsev et al., 2D Mater. 4 (2017) 025072; A. Fete et al., Appl. Phys. Lett. 109 (2016) 192601] to millimeter-scale samples [E. F. Talantsev et al., Sci. Rep. 7 (2017) 10010]. The basic empirical equation which quantitatively accurately described experimental Jc(sf,T) was proposed by Talantsev and Tallon [Nat. Commun. 6 (2015) 7820] and it was the relevant critical field (i.e. thermodynamic field, Bc, for type-I and lower critical field, Bc1, for type-II superconductors) divided by the London penetration depth, λL. In this paper, we report new findings relating to this empirical equation. It is that the critical wavelength of the de Broglie wave, λdB,c, of the superconducting charge carrier which within a numerical pre-factor is equal to the largest of two characteristic lengths of Ginzburg-Landau theory, i.e. the coherence length, ξ, for type-I superconductors or the London penetration depth, λL, for type-II superconductors. We also formulate a microscopic criterion for the onset of dissipative transport current flow: ps ṡ 2ṡλL ln(1+2ṡ(λL ξ )) ≥ 1 2 ṡ ( h 2π), where ps is the charge carrier momentum, h is Planck’s constant and the inequality sign “ <” is reserved for the dissipation-free flow.

  4. Wavelength dependent deformation in a laser peened Ti-2.5Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Umapathi, A., E-mail: umapathi.arimakula@gmail.com; Swaroop, S., E-mail: n.r.sathya.swaroop@gmail.com

    2017-01-27

    Laser peening without coating (LPwC) was performed on a Ti-2.5Cu alloy at wavelengths of 1064 and 532 nm and at a constant power density of approximately 7 GW cm{sup −2} with overlap rates of 53%, 63% and 73%. Surface softening due to thermal interaction of laser beam with material was observed till a depth of 500 µm (at 532 nm) and 200 µm (at 1064 nm), based on hardness data. This was corroborated (rather weakly) by residual stress analysis. In addition, softening due to mechanical effects (adiabatic heating) was observed in the bulk. Although there was an increase in mechanical softening with increase in overlap rates at 532 nm, it was observed, upon comparison with peened samples at 1064 nm, that the mechanical softening is a function of wavelength of radiation used for peening. It was observed that the onset of softening was earlier if the wavelength was shorter. Further, evidence of hardening in the form of twinning was found for the 1064 nm case while it was absent for the 532 nm case, for 73% overlap. The workhardened depth was more than 1000 µm, not observed in earlier studies based on residual stress analysis. The direct consequence of softening effect was found in the fatigue results. The fatigue life extended by a factor of 1.4 and 2.3 for the samples peened at 532 nm and 1064 nm respectively, consistent with the observed wavelength dependent onset of softening.

  5. Wavelength dependence of superhumps in VW Hyi

    International Nuclear Information System (INIS)

    Amerongen, S. van; Bovenschen, H.; Paradijs, J. van

    1987-01-01

    Results are presented of five-colour photometric observations of the SU UMa system VW Hyi, made on six nights during the November 1984 superoutburst. The light curve is dominated by superhump variations, whose amplitude in all passbands decreases with time (in the V-band from 0.16 mag about 4.5 day after the superoutburst reached maximum brightness, to 0.10 mag about 5 day later). The superhump light curve depends strongly on wavelength. In particular it appears that the light curves in different passbands are mutually shifted: the larger the wavelength, the more the light curve is delayed. (author)

  6. Short wavelength sources and atoms and ions

    International Nuclear Information System (INIS)

    Kennedy, E.T.

    2008-01-01

    The interaction of ionizing radiation with atoms and ions is a key fundamental process. Experimental progress has depended in particular on the development of short wavelength light sources. Laser-plasma and synchrotron sources have been exploited for several decades and most recently the development of short wavelength Free Electron Laser (FEL) sources is revolutionizing the field. This paper introduces laser plasma and synchrotron sources through examples of their use in studies of the interaction of ionizing radiation with atoms and ions, ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides. The new FEL source (FLASH) at DESY is introduced. (author)

  7. Nation-Scale Adoption of Shorter Breast Radiation Therapy Schedules Can Increase Survival in Resource Constrained Economies: Results From a Markov Chain Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Atif J., E-mail: atif.j.khan@rutgers.edu [Department of Radiation Oncology, Robert Wood Johnson Medical School/Cancer Institute of New Jersey, New Brunswick, New Jersey (United States); Rafique, Raza [Suleman Dawood School of Business, Lahore University of Management Sciences, Lahore (Pakistan); Zafar, Waleed [Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore (Pakistan); Shah, Chirag [Department of Radiation Oncology, Cleveland Clinic, Cleveland, Ohio (United States); Haffty, Bruce G. [Department of Radiation Oncology, Robert Wood Johnson Medical School/Cancer Institute of New Jersey, New Brunswick, New Jersey (United States); Vicini, Frank [Michigan HealthCare Professionals, Farmington Hills, Michigan (United States); Jamshed, Arif [Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore (Pakistan); Zhao, Yao [Rutgers University School of Business, Newark, New Jersey (United States)

    2017-02-01

    Purpose: Hypofractionated whole breast irradiation and accelerated partial breast irradiation (APBI) offer women options for shorter courses of breast radiation therapy. The impact of these shorter schedules on the breast cancer populations of emerging economies with limited radiation therapy resources is unknown. We hypothesized that adoption of these schedules would improve throughput in the system and, by allowing more women access to life-saving treatments, improve patient survival within the system. Methods and Materials: We designed a Markov chain model to simulate the different health states that a postlumpectomy or postmastectomy patient could enter over the course of a 20-year follow-up period. Transition rates between health states were adapted from published data on recurrence rates. We used primary data from a tertiary care hospital in Lahore, Pakistan, to populate the model with proportional use of mastectomy versus breast conservation and to estimate the proportion of patients suitable for APBI. Sensitivity analyses on the use of APBI and relative efficacy of APBI were conducted to study the impact on the population. Results: The shorter schedule resulted in more women alive and more women remaining without evidence of disease (NED) compared with the conventional schedule, with an absolute difference of about 4% and 7% at 15 years, respectively. Among women who had lumpectomies, the chance of remaining alive and with an intact breast was 62% in the hypofractionation model and 54% in the conventional fractionation model. Conclusions: Increasing throughput in the system can result in improved survival, improved chances of remaining without evidence of disease, and improved chances of remaining alive with a breast. These findings are significant and suggest that adoption of hypofractionation in emerging economies is not simply a question of efficiency and cost but one of access to care and patient survivorship.

  8. Nation-Scale Adoption of Shorter Breast Radiation Therapy Schedules Can Increase Survival in Resource Constrained Economies: Results From a Markov Chain Analysis

    International Nuclear Information System (INIS)

    Khan, Atif J.; Rafique, Raza; Zafar, Waleed; Shah, Chirag; Haffty, Bruce G.; Vicini, Frank; Jamshed, Arif; Zhao, Yao

    2017-01-01

    Purpose: Hypofractionated whole breast irradiation and accelerated partial breast irradiation (APBI) offer women options for shorter courses of breast radiation therapy. The impact of these shorter schedules on the breast cancer populations of emerging economies with limited radiation therapy resources is unknown. We hypothesized that adoption of these schedules would improve throughput in the system and, by allowing more women access to life-saving treatments, improve patient survival within the system. Methods and Materials: We designed a Markov chain model to simulate the different health states that a postlumpectomy or postmastectomy patient could enter over the course of a 20-year follow-up period. Transition rates between health states were adapted from published data on recurrence rates. We used primary data from a tertiary care hospital in Lahore, Pakistan, to populate the model with proportional use of mastectomy versus breast conservation and to estimate the proportion of patients suitable for APBI. Sensitivity analyses on the use of APBI and relative efficacy of APBI were conducted to study the impact on the population. Results: The shorter schedule resulted in more women alive and more women remaining without evidence of disease (NED) compared with the conventional schedule, with an absolute difference of about 4% and 7% at 15 years, respectively. Among women who had lumpectomies, the chance of remaining alive and with an intact breast was 62% in the hypofractionation model and 54% in the conventional fractionation model. Conclusions: Increasing throughput in the system can result in improved survival, improved chances of remaining without evidence of disease, and improved chances of remaining alive with a breast. These findings are significant and suggest that adoption of hypofractionation in emerging economies is not simply a question of efficiency and cost but one of access to care and patient survivorship.

  9. Shorter sleep duration is associated with social impairment and comorbidities in ASD.

    Science.gov (United States)

    Veatch, Olivia J; Sutcliffe, James S; Warren, Zachary E; Keenan, Brendan T; Potter, Melissa H; Malow, Beth A

    2017-07-01

    Sleep disturbance, particularly insomnia, is common in children with autism spectrum disorders (ASD). Furthermore, disturbed sleep affects core symptoms and other related comorbidities. Understanding the causes and consequences of sleep disturbances in children with ASD is an important step toward mitigating these symptoms. To better understand the connection between sleep duration and ASD severity, we analyzed ASD-related symptoms using the Autism Diagnostic Interview-Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS), IQ scores, and parent reports of the average amount of time slept per night that were available in the medical histories of 2,714 children with ASD in the Simons Simplex Collection (SSC). The mean (SD) sleep duration was 555 minutes. Sleep duration and severity of core ASD symptoms were negatively correlated, and sleep duration and IQ scores were positively correlated. Regression results indicated that more severe social impairment, primarily a failure to develop peer relationships, is the core symptom most strongly associated with short sleep duration. Furthermore, increased severity for numerous maladaptive behaviors assessed on the Child Behavior Checklist, as well as reports of attention deficit disorder, depressive disorder, and obsessive compulsive disorder were associated with short sleep duration. Severity scores for social/communication impairment and restricted and repetitive behaviors (RRB) were increased, and IQ scores were decreased, for children reported to sleep ≤420 minutes per night (lower 5th percentile) compared to children sleeping ≥660 minutes (upper 95th percentile). Our results indicate that reduced amounts of sleep are related to more severe symptoms in children with ASD. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1221-1238. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. © 2017 International Society for Autism

  10. Excision of oral mucocele by different wavelength lasers

    Directory of Open Access Journals (Sweden)

    Umberto Romeo

    2013-01-01

    Full Text Available Background: Mucocele is a common benign neoplasm of oral soft tissues and the most common after fibroma. It generally occurs in the lower lip and its treatment includes excision of cyst and the responsible salivary gland, in order to prevent recurrences. Aims: To evaluate the capability of three different lasers in performing the excision of labial mucocele with two different techniques. Materials and Methods: In the presented cases, excision was performed using two different techniques (circumferential incision technique and mucosal preservation technique and three different laser wavelengths (Er,Cr:YSGG 2780 nm, diode 808 nm, and KTP 532 nm. Results: All the tested lasers, regardless of wavelength, showed many advantages (bloodless surgical field, no postoperative pain, relative speed, and easy execution. The most useful surgical technique depends on clinical features of the lesion. Conclusion: Tested lasers, with both techniques, are helpful in the management of labial mucocele.

  11. A readout system for the wavelength-shifting optical module

    Energy Technology Data Exchange (ETDEWEB)

    Foesig, Carl-Christian; Boeser, Sebastian [Johannes Gutenberg-Universitaet, Mainz (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    The success of IceCube and the plans for an IceCube-Gen2 stimulate the development of new photo sensors. The approach of the Wavelength-shifting Optical Module is to provide a device which has a low dark noise rate combined with a high detection efficiency. A small PMT is used to detect red shifted photons guided in a coated PMMA tube, originally emitted by a wavelength shifting coating that absorbs photons in the UV Region. We have studied several PMTs for their usability with the IceCube-Gen2 readout system. Relevant parameters are the pulse widths in relation to the bandwidth of the IceCube-Gen2 readout electronics and the dark noise rates.

  12. Short wavelength limits of current shot noise suppression

    International Nuclear Information System (INIS)

    Nause, Ariel; Dyunin, Egor; Gover, Avraham

    2014-01-01

    Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect

  13. Short wavelength limits of current shot noise suppression

    Energy Technology Data Exchange (ETDEWEB)

    Nause, Ariel, E-mail: arielnau@post.tau.ac.il [Faculty of Exact Sciences, Department of Physics, Tel Aviv University, Tel Aviv (Israel); Dyunin, Egor; Gover, Avraham [Faculty of Engineering, Department of Physical Electronics, Tel Aviv University, Tel Aviv (Israel)

    2014-08-15

    Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect.

  14. A generalized non-Gaussian consistency relation for single field inflation

    Science.gov (United States)

    Bravo, Rafael; Mooij, Sander; Palma, Gonzalo A.; Pradenas, Bastián

    2018-05-01

    We show that a perturbed inflationary spacetime, driven by a canonical single scalar field, is invariant under a special class of coordinate transformations together with a field reparametrization of the curvature perturbation in co-moving gauge. This transformation may be used to derive the squeezed limit of the 3-point correlation function of the co-moving curvature perturbations valid in the case that these do not freeze after horizon crossing. This leads to a generalized version of Maldacena's non-Gaussian consistency relation in the sense that the bispectrum squeezed limit is completely determined by spacetime diffeomorphisms. Just as in the case of the standard consistency relation, this result may be understood as the consequence of how long-wavelength modes modulate those of shorter wavelengths. This relation allows one to derive the well known violation to the consistency relation encountered in ultra slow-roll, where curvature perturbations grow exponentially after horizon crossing.

  15. Shorter HBIG administration is not associated to HBV recurrence when receiving combined prophylaxis after liver transplantation.

    Science.gov (United States)

    Lens, Sabela; García-Eliz, María; Fernández, Inmaculada; Castells, Lluis; Bonacci, Martin; Mas, Antoni; Crespo, Gonzalo; Buti, María; Prieto, Martín; Forns, Xavier

    2018-04-16

    The combination of hepatitis B immunoglobulin (HBIG) and a nucleos(t)ide analogs (NA) has markedly reduced the rate of hepatitis B (HBV) recurrence after liver transplantation (LT); however, the optimal duration of HBIG has not been clarified. This lack of consensus perpetuates the use of different strategies. The aim of this study was to evaluate the risk factors associated to HBV recurrence after LT in a large cohort of patients under different HBIG regimens. Retrospective multicenter analysis of HBV-related LT recipients receiving combined prophylaxis (HBIG+NA). The strategy of short-term HBIG was compared to life-long administration. HBV recurrence was defined as positive HBsAg after LT. 338 patients were analyzed. After a median follow-up period of 72 months, 37 patients (11%) developed HBV recurrence. Hepatocellular carcinoma (HCC) recurrence and lamivudine resistance after LT were the only factors independently associated to HBV recurrence (HR 5.4[2.3-12] and 9.3[4.2-20], respectively pHBV recurrence was transient (16 patients), persistent (15) or alternant (6). The HBIG regimen did not have an impact on the rate or evolution of HBV recurrence. Overall, patient survival was good and not influenced by HBV recurrence (82% at 5 years). Fulminant liver failure, hepatitis C coinfection or HCC at LT were independent risk factors for lower survival. LT is an effective treatment for HBV-related liver disease. Since the introduction of combined prophylaxis the rate of HBV recurrence is very low. However, life-long HBIG administration does not seem necessary to reduce HBV recurrence. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  16. Topology Optimization of Sub-Wavelength Antennas

    DEFF Research Database (Denmark)

    Erentok, Aycan; Sigmund, Ole

    2011-01-01

    We propose a topology optimization strategy for the systematic design of a three-dimensional (3D), conductor-based sub-wavelength antenna. The post-processed finite-element (FE) models of the optimized structure are shown to be self-resonant, efficient and exhibit distorted omnidirectional...

  17. Characterization of ethanol concentrations at ultraviolet wavelength ...

    African Journals Online (AJOL)

    This paper presents the measurement of optical absorption spectrum for different concentrations of ethanol at ultraviolet wavelength. Ethanol absorption spectrum was measured using portable spectroscopy setup from Avantes. It consists of Balanced Deuterium Halogen light source and spectrometer. The light source can ...

  18. Smart wavelength meter for integrated photonics

    NARCIS (Netherlands)

    Benelajla, Meryem; Taballione, Caterina; Boller, Klaus J.

    2017-01-01

    Thermally tunable SiN waveguide microring resonators in connection with neural network readout algorithms appear promising for use as integrated optical wavelength meters. So far, we have observed long-term reliability and a temperature immunity of the readout across several degrees of ambient

  19. An automated wavelength selection for flame spectroscopy

    International Nuclear Information System (INIS)

    Hurteau, M.; Mislan, J.P.; Ashley, R.W.

    1976-01-01

    A simple electro-mechanical programming system is described for use with a flame spectrophotometer. Its application for automated sequential multi-element analysis is illustrated. Reproducibility of wavelength settings are within +-0.5 A. Precision and sensitivities are at least as good as those obtained for single element determinations. (author)

  20. Alien wavelength modeling tool and field trial

    DEFF Research Database (Denmark)

    Sambo, N.; Sgambelluri, A.; Secondini, M.

    2015-01-01

    A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been...

  1. Two-wavelength spatial-heterodyne holography

    Science.gov (United States)

    Hanson, Gregory R.; Bingham, Philip R.; Simpson, John T.; Karnowski, Thomas P.; Voelkl, Edgar

    2007-12-25

    Systems and methods are described for obtaining two-wavelength differential-phase holograms. A method includes determining a difference between a filtered analyzed recorded first spatially heterodyne hologram phase and a filtered analyzed recorded second spatially-heterodyned hologram phase.

  2. Why shorter half-times of repair lead to greater damage in pulsed brachytherapy

    International Nuclear Information System (INIS)

    Fowler, J.F.

    1993-01-01

    Pulsed brachytherapy consists of replacing continuous irradiation at low dose-rate with a series of medium dose-rate fractions in the same overall time and to the same total dose. For example, pulses of 1 Gy given every 2 hr or 2 Gy given every 4 hr would deliver the same 70 Gy in 140 hr as continuous irradiation at 0.5 Gy/hr. If higher dose-rates are used, even with gaps between the pulses, the biological effects are always greater. Provided that dose rates in the pulse do not exceed 3 Gy/hr, and provided that pulses are given as often as every 2 hr, the inevitable increases of biological effect are no larger than a few percent (of biologically effective dose or extrapolated response dose). However, these increases are more likely to exceed 10% (and thus become clinically significant) if the half-time of repair of sublethal damage is short (less than 1 hr) rather than long. This somewhat unexpected finding is explained in detail here. The rise and fall of Biologically Effective Dose (and hence of Relative Effectiveness, for a constant dose in each pulse) is calculated during and after single pulses, assuming a range of values of T 1/2 , the half-time of sublethal damage repair. The area under each curve is proportional to Biologically Effective Dose and therefore to log cell kill. Pulses at 3 Gy/hr do yield greater biological effect (dose x integrated Relative Effectiveness) than lower dose-rate pulses or continuous irradiation at 0.5 Gy/hr. The contrast is greater for the short T 1/2 of 0.5 hr than for the longer T 1/2 of 1.5 hr. More biological damage will be done (compared with traditional low dose rate brachytherapy) in tissues with short T 1/2 (0.1-1 hr) than in tissues with longer T 1/2 values. 8 refs., 3 figs

  3. Bleaching of the thermoluminescence of feldspars by selected wavelengths present in sunlight

    International Nuclear Information System (INIS)

    Robertson, G.B.; Prescott, J.R.; Hutton, J.T.

    1993-01-01

    Feldspars occur in many sediments, and dating them by thermoluminescence (TL) requires a knowledge of how efficiently sunlight bleaches these minerals. The relative bleaching efficiencies of various wavelengths have been investigated for four alkali feldspars and an oligoclase, using the natural TL of the samples and the artificial TL induced by laboratory irradiation, bleached by wavelengths in the range 322-550 nm. Ultraviolet wavelengths are more efficient than the longer wavelengths at bleaching all the glow-curve peaks and are responsible for most of the phototransfer from high-temperature peaks to low-temperature peaks. Some feldspars show an initial increase in TL intensity with bleaching. Two sanidines of similar bulk composition but different TL glow curves show different dependences on bleaching wavelength. In a sodic sanidine with a dominant 240 o C peak the energy required to bleach to 50% was a thousand times greater at 550 nm than at 322 nm. In contrast, another sanidine with a complex glow curve between 150 and 450 o C showed a much slower change in the 330 o C peak with wavelength - a factor of 10 between 322 and 550 nm - with a region between 400 and 500 nm which was almost independent of wavelength. This behaviour is explained by competing mechanisms of phototransfer and bleaching which depend on wavelength in different ways. (author)

  4. Sterol 27-Hydroxylase Polymorphism Significantly Associates With Shorter Telomere, Higher Cardiovascular and Type-2 Diabetes Risk in Obese Subjects

    Directory of Open Access Journals (Sweden)

    Sofia Pavanello

    2018-06-01

    Full Text Available Background/objectivesThe pathologic relationship linking obesity and lipid dismetabolism with earlier onset of aging-related disorders, including cardiovascular disease (CVD and type-2 diabetes (T2D, is not fully elucidate. Chronic inflammatory state, in obese individuals, may accelerate cellular aging. However, leukocyte telomere length (LTL, the cellular biological aging indicator, is elusively linked with obesity. Recent studies indicate that sterol 27-hydroxylase (CYP27A1 is an emerging antiatherogenic enzyme, that, by converting extrahepatic cholesterol to 27-hydroxycholesterol, facilitates cholesterol removal via high-density lipoprotein-cholesterol (HDL-C. We tested the hypothesis that obese subjects who carry at least three copies of CYP27A1 low-hydroxylation (LH activity genome-wide-validated alleles (rs4674345A, rs1554622A, and rs4674338G present premature aging, as reflected in shorter LTL and higher levels of CVD/T2D risk factors, including reduced HDL-C.Subjects/methodsObese subjects from SPHERE project {n = 1,457; overweight [body mass index (BMI 25–30 kg/m2] 65.8% and severe-obese (BMI > 30 kg/m2 34.2%} were characterized for the presence from 0 to 6 LH-CYP27A1 allele copy number. Univariate and multivariable sex–age–smoking-adjusted linear-regression models were performed to compare CVD/T2D risk factors and biological aging (LTL in relation to the combined BMI-LH groups: overweight-LH: 0–2, overweight-LH: 3–6, severe-obese-LH: 0–2, and severe-obese-LH: 3–6.ResultsHigher LTL attrition was found in severe-obese than overweight individuals (p < 0.001. Multivariable model reveals that among severe-obese patients those with LH: 3–6 present higher LTL attrition than LH: 0–2 (p < 0.05. Univariate and multivariable models remarkably show that insulin resistance is higher both in overweight-LH: 3–6 vs overweight-LH: 0–2 (p < 0.001 and in severe-obese-LH: 3–6 vs severe-obese-LH: 0–2 (p

  5. Swift Multi-wavelength Observing Campaigns: Strategies and Outcomes

    Science.gov (United States)

    Krimm, Hans A.

    2007-01-01

    The Swift gamma-ray burst explorer has been operating since December 2004 as both a gamma-ray burst (GRB) monitor and telescope and a multi-wavelength observatory, covering the energy range from V band and near UV to hard X rays above 150 keV. It is designed to rapidly repoint to observe newly discovered GRBs, and this maneuverability, combined with an easily changed observing program, allows Swift to also be an effective multiwavelength observatory for non-GRB targets, both as targets of opportunity and pre-planned multi-wavelength observing campaigns. Blazars are particularly attractive targets for coordinated campaigns with TeV experiments since many blazars are bright in both the hard X-ray and TeV energy ranges. Successful coordinated campaigns have included observations of 3C454.3 during its 2005 outburst. The latest Swift funding cycles allow for non- GRB related observations to be proposed. The Burst Alert Telescope on Swift also serves as a hard X-ray monitor with a public web page that includes light curves for over 400 X-ray sources and is used to alert the astronomical community about increased activity from both known and newly discovered sources. This presentation mill include Swift capabilities, strategies and policies for coordinated multi-wavelength observations as well as discussion of the potential outcomes of such campaigns.

  6. Linear response to long wavelength fluctuations using curvature simulations

    Energy Technology Data Exchange (ETDEWEB)

    Baldauf, Tobias; Zaldarriaga, Matias [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ (United States); Seljak, Uroš [Physics Department, Astronomy Department and Lawrence Berkeley National Laboratory, University of California, Berkeley, CA (United States); Senatore, Leonardo, E-mail: baldauf@ias.edu, E-mail: useljak@berkeley.edu, E-mail: senatore@stanford.edu, E-mail: matiasz@ias.edu [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA (United States)

    2016-09-01

    We study the local response to long wavelength fluctuations in cosmological N -body simulations, focusing on the matter and halo power spectra, halo abundance and non-linear transformations of the density field. The long wavelength mode is implemented using an effective curved cosmology and a mapping of time and distances. The method provides an alternative, more direct, way to measure the isotropic halo biases. Limiting ourselves to the linear case, we find generally good agreement between the biases obtained from the curvature method and the traditional power spectrum method at the level of a few percent. We also study the response of halo counts to changes in the variance of the field and find that the slope of the relation between the responses to density and variance differs from the naïve derivation assuming a universal mass function by approximately 8–20%. This has implications for measurements of the amplitude of local non-Gaussianity using scale dependent bias. We also analyze the halo power spectrum and halo-dark matter cross-spectrum response to long wavelength fluctuations and derive second order halo bias from it, as well as the super-sample variance contribution to the galaxy power spectrum covariance matrix.

  7. The dynamics of interacting nonlinearities governing long wavelength driftwave turbulence

    International Nuclear Information System (INIS)

    Newman, D.E.

    1993-09-01

    Because of the ubiquitous nature of turbulence and the vast array of different systems which have turbulent solutions, the study of turbulence is an area of active research. Much present day understanding of turbulence is rooted in the well established properties of homogeneous Navier-Stokes turbulence, which, due to its relative simplicity, allows for approximate analytic solutions. This work examines a group of turbulent systems with marked differences from Navier-Stokes turbulence, and attempts to quantify some of their properties. This group of systems represents a variety of drift wave fluctuations believed to be of fundamental importance in laboratory fusion devices. From extensive simulation of simple local fluid models of long wavelength drift wave turbulence in tokamaks, a reasonably complete picture of the basic properties of spectral transfer and saturation has emerged. These studies indicate that many conventional notions concerning directions of cascades, locality and isotropy of transfer, frequencies of fluctuations, and stationarity of saturation are not valid for moderate to long wavelengths. In particular, spectral energy transfer at long wavelengths is dominated by the E x B nonlinearity, which carries energy to short scale in a manner that is highly nonlocal and anisotropic. In marked contrast to the canonical self-similar cascade dynamics of Kolmogorov, energy is efficiently passed between modes separated by the entire spectrum range in a correlation time. At short wavelengths, transfer is dominated by the polarization drift nonlinearity. While the standard dual cascade applies in this subrange, it is found that finite spectrum size can produce cascades that are reverse directed and are nonconservative in enstrophy and energy similarity ranges. In regions where both nonlinearities are important, cross-coupling between the nolinearities gives rise to large no frequency shifts as well as changes in the spectral dynamics

  8. Long wavelength irregularities in the equatorial electrojet

    International Nuclear Information System (INIS)

    Kudeki, E.; Farley, D.T.; Fejer, B.G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear theory of the electrojet instability explains this and several other observed features of these dominant primary waves

  9. Design alternatives for wavelength routing networks

    Science.gov (United States)

    Miliotis, K.; Papadimitriou, G. I.; Pomportsis, A. S.

    2003-03-01

    This paper attempts to provide a high level overview of many of the technologies employed in optical networks with a focus on wavelength-routing networks. Optical networks involve a number of technologies from the physics of light through protocols and networks architectures. In fact there is so much technology and know-how that most people involved with optical networks only have a full understanding of the narrow area they deal with. We start first examining the principles that govern light and its use as a wave guide, and then turn our focus to the various components that constitute an optical network and conclude with the description of all optical networks and wavelength-routed networks in greater detail.

  10. Long wavelength irregularities in the equatorial electrojet

    OpenAIRE

    Kudeki, E.; Farley, D. T.; Fejer, Bela G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach...

  11. Optical Detection in Ultrafast Short Wavelength Science

    International Nuclear Information System (INIS)

    Fullagar, Wilfred K.; Hall, Chris J.

    2010-01-01

    A new approach to coherent detection of ionising radiation is briefly motivated and recounted. The approach involves optical scattering of coherent light fields by colour centres in transparent solids. It has significant potential for diffractive imaging applications that require high detection dynamic range from pulsed high brilliance short wavelength sources. It also motivates new incarnations of Bragg's X-ray microscope for pump-probe studies of ultrafast molecular structure-dynamics.

  12. Optically coupled cavities for wavelength switching

    Energy Technology Data Exchange (ETDEWEB)

    Costazo-Caso, Pablo A; Granieri, Sergio; Siahmakoun, Azad, E-mail: pcostanzo@ing.unlp.edu.ar, E-mail: granieri@rose-hulman.edu, E-mail: siahmako@rose-hulman.edu [Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN 47803 (United States)

    2011-01-01

    An optical bistable device which presents hysteresis behavior is proposed and experimentally demonstrated. The system finds applications in wavelength switching, pulse reshaping and optical bistability. It is based on two optically coupled cavities named master and slave. Each cavity includes a semiconductor optical amplifier (SOA), acting as the gain medium of the laser, and two pair of fiber Bragg gratings (FBG) which define the lasing wavelength (being different in each cavity). Finally, a variable optical coupler (VOC) is employed to couple both cavities. Experimental characterization of the system performance is made analyzing the effects of the coupling coefficient between the two cavities and the driving current in each SOA. The properties of the hysteretic bistable curve and switching can be controlled by adjusting these parameters and the loss in the cavities. By selecting the output wavelength ({lambda}{sub 1} or {lambda}{sub 2}) with an external filter it is possible to choose either the invert or non-invert switched signal. Experiments were developed employing both optical discrete components and a photonic integrated circuit. They show that for 8 m-long cavities the maximum switching frequency is about 500 KHz, and for 4 m-long cavities a minimum rise-time about 21 ns was measured. The switching time can be reduced by shortening the cavity lengths and using photonic integrated circuits.

  13. Multiple wavelength X-ray monochromators

    International Nuclear Information System (INIS)

    Steinmeyer, P.A.

    1992-01-01

    An improved apparatus and method is provided for separating input x-ray radiation containing first and second x-ray wavelengths into spatially separate first and second output radiation which contain the first and second x-ray wavelengths, respectively. The apparatus includes a crystalline diffractor which includes a first set of parallel crystal planes, where each of the planes is spaced a predetermined first distance from one another. The crystalline diffractor also includes a second set of parallel crystal planes inclined at an angle with respect to the first set of crystal planes where each of the planes of the second set of parallel crystal planes is spaced a predetermined second distance from one another. In one embodiment, the crystalline diffractor is comprised of a single crystal. In a second embodiment, the crystalline diffractor is comprised of a stack of two crystals. In a third embodiment, the crystalline diffractor includes a single crystal that is bent for focusing the separate first and second output x-ray radiation wavelengths into separate focal points. 3 figs

  14. 3d-4p x-ray spectrum emitted by highly ionized uranium from a laser-produced plasma in the 3.8<λ<4.4-A wavelength range

    International Nuclear Information System (INIS)

    Mandelbaum, P.; Seely, J.F.; Kania, D.R.; Kauffman, R.L.

    1992-01-01

    This work extends a previous analysis of the x-ray spectrum of a laser-produced uranium plasma [P. Mandelbaum et al., Phys. Rev. A 44, 5752 (1991)] to the longer-wavelength range (3.8 +65 ) through As-like (U +59 ) isoelectronic sequences are identified in the spectrum, in good agreement with the previous analysis of the spectrum emitted at shorter wavelengths

  15. First-Light Galaxies or Intrahalo Stars: Multi-Wavelength Measurements of the Infrared Background Anisotropies

    Science.gov (United States)

    Cooray, Asantha

    The research program described in this proposal can be broadly described as data analysis, measurement, and interpretation of the spatial fluctuations of the unresolved cosmic IR background. We will focus primarily on the background at optical and near-IR wavelengths as probed by Hubble and Spitzer. As absolute background intensity measurements are challenging, the focus is on the spatial fluctuations similar to the anisotropiesof the cosmic microwave background (CMB). Measurements of the unresolved Spitzer fluctuations by two independent teams on multiple fields agree within the measurement errors. However, there are now two interpretations on the origin of the unresolved IRAC fluctuations. One involves a population of faint sources at very high redshifts (z > 6) during the epoch of reionization. The second interpretation involves the integrated emission from intrahalo light associated with diffuse stars in the outskirts of z of 1 to 3 dark matter halos of galaxies. We now propose to further test these two interpretations with a new set of measurements at shorter IR and optical wavelengths with HST/ACS and WFC3 overlapping with deep IRAC surveys. A multi-wavelength study from 0.5 to 4.5 micron will allow us to independently determine the relative contribution of intrahalo light and z > 8 faint galaxies to the unresolved IR fluctuations. We will also place strong limits on the surface density of faint sources at z > 8. Such a limit will be useful for planning deep surveys with JWST. Moving to the recent wide IRAC fields with the warm mission, we propose to study fluctuations at tens of degree angular scales. At such large angular scales IRAC fluctuations should trace diffuse Galactic light (DGL), ISM dust-scattered starlight in our Galaxy. We will measure the amplitude and slope of the DGL power spectrum and compare them to measurements of the Galactic dust power spectrum from IRAS and Planck and study if the large degree-scale fluctuations seen in CIBER can be

  16. Optimization of a shorter variable-acquisition time for legs to achieve true whole-body PET/CT images.

    Science.gov (United States)

    Umeda, Takuro; Miwa, Kenta; Murata, Taisuke; Miyaji, Noriaki; Wagatsuma, Kei; Motegi, Kazuki; Terauchi, Takashi; Koizumi, Mitsuru

    2017-12-01

    The present study aimed to qualitatively and quantitatively evaluate PET images as a function of acquisition time for various leg sizes, and to optimize a shorter variable-acquisition time protocol for legs to achieve better qualitative and quantitative accuracy of true whole-body PET/CT images. The diameters of legs to be modeled as phantoms were defined based on data derived from 53 patients. This study analyzed PET images of a NEMA phantom and three plastic bottle phantoms (diameter, 5.68, 8.54 and 10.7 cm) that simulated the human body and legs, respectively. The phantoms comprised two spheres (diameters, 10 and 17 mm) containing fluorine-18 fluorodeoxyglucose solution with sphere-to-background ratios of 4 at a background radioactivity level of 2.65 kBq/mL. All PET data were reconstructed with acquisition times ranging from 10 to 180, and 1200 s. We visually evaluated image quality and determined the coefficient of variance (CV) of the background, contrast and the quantitative %error of the hot spheres, and then determined two shorter variable-acquisition protocols for legs. Lesion detectability and quantitative accuracy determined based on maximum standardized uptake values (SUV max ) in PET images of a patient using the proposed protocols were also evaluated. A larger phantom and a shorter acquisition time resulted in increased background noise on images and decreased the contrast in hot spheres. A visual score of ≥ 1.5 was obtained when the acquisition time was ≥ 30 s for three leg phantoms, and ≥ 120 s for the NEMA phantom. The quantitative %errors of the 10- and 17-mm spheres in the leg phantoms were ± 15 and ± 10%, respectively, in PET images with a high CV (scan mean SUV max of three lesions using the current fixed-acquisition and two proposed variable-acquisition time protocols in the clinical study were 3.1, 3.1 and 3.2, respectively, which did not significantly differ. Leg acquisition time per bed position of even 30-90

  17. Induction of a shorter compression phase is correlated with a deeper chest compression during metronome-guided cardiopulmonary resuscitation: a manikin study.

    Science.gov (United States)

    Chung, Tae Nyoung; Bae, Jinkun; Kim, Eui Chung; Cho, Yun Kyung; You, Je Sung; Choi, Sung Wook; Kim, Ok Jun

    2013-07-01

    Recent studies have shown that there may be an interaction between duty cycle and other factors related to the quality of chest compression. Duty cycle represents the fraction of compression phase. We aimed to investigate the effect of shorter compression phase on average chest compression depth during metronome-guided cardiopulmonary resuscitation. Senior medical students performed 12 sets of chest compressions following the guiding sounds, with three down-stroke patterns (normal, fast and very fast) and four rates (80, 100, 120 and 140 compressions/min) in random sequence. Repeated-measures analysis of variance was used to compare the average chest compression depth and duty cycle among the trials. The average chest compression depth increased and the duty cycle decreased in a linear fashion as the down-stroke pattern shifted from normal to very fast (pmetronome-guided cardiopulmonary resuscitation.

  18. TIA model is attainable in Wistar rats by intraluminal occlusion of the MCA for 10min or shorter.

    Science.gov (United States)

    Durukan Tolvanen, A; Tatlisumak, E; Pedrono, E; Abo-Ramadan, U; Tatlisumak, T

    2017-05-15

    Transient ischemic attack (TIA) has received only little attention in the experimental research field. Recently, we introduced a TIA model for mice, and here we set similar principles for simulating this human condition in Wistar rats. In the model: 1) transient nature of the event is ensured, and 2) 24h after the event animals are free from any sensorimotor deficit and from any detectable lesion by magnetic resonance imaging (MRI). Animals experienced varying durations of ischemia (5, 10, 12.5, 15, 25, and 30min, n=6-8pergroup) by intraluminal middle cerebral artery occlusion (MCAO). Ischemia severity and reperfusion rates were controlled by cerebral blood flow measurements. Sensorimotor neurological evaluations and MRI at 24h differentiated between TIA and ischemic stroke. Hematoxylin and eosin staining and apoptotic cell counts revealed pathological correlates of the event. We found that already 12.5min of ischemia was long enough to induce ischemic stroke in Wistar rats. Ten min or shorter durations induced neither gross neurological deficits nor infarcts visible on MRI, but histologically caused selective neuronal necrosis. A separate group of animals with 10min of ischemia followed up to 1week after reperfusion remained free of infarction and any MRI signal change. Thus, 10min or shorter focal cerebral ischemia induced by intraluminal MCAO in Wistar rats provides a clinically relevant TIA the rat. This model is useful for studying molecular correlates of TIA. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Urdu translation and validation of shorter version of Positive Affect and Negative Affect Schedule (PANAS) on Pakistani bank employees.

    Science.gov (United States)

    Akhter, Noreen

    2017-10-01

    To translate, adapt and validate shorter version of positive affect and negative affect scale on Pakistani corporate employees. This cross-sectional study was conducted in the twin cities of Islamabad and Rawalpindi from October 2014 to December 2015. The study was completed into two independent parts. In part one, the scale was translated by forward translation. Then it was pilot-tested and administered on customer services employees from commercial banks and the telecommunication sector. Data of the pilot study was analysed by using exploratory factor analysis to extract the initial factor of positive affect and negative affect scale. Part two comprised the main study. Commercial bank employees were included in the sample using convenient sampling technique. Data of the main study was analysed using confirmatory factor analysis in order to establish construct validity of positive affect and negative affect scale. There were145 participants in the first part of the study and 495 in the second. Results of confirmatory factor analysis confirmed the two-factor structure of positive affect and negative affect scale suggesting that the scale has two distinct domains, i.e. positive affect and negative affect. The shorter version of positive affect and negative affect scale was found to be a valid and reliable measure.

  20. Use of a novel shorter minimum caliber needle for creating endoscopic tattoos for preoperative localization: a comparative ex vivo study.

    Science.gov (United States)

    Imai, Kenichiro; Hotta, Kinichi; Ito, Sayo; Yamaguchi, Yuichiro; Kawakami, Takeshi; Wada, Takuya; Igarashi, Kimihiro; Kishida, Yoshihiro; Kinugasa, Yusuke; Kawata, Noboru; Tanaka, Masaki; Kakushima, Naomi; Takizawa, Kohei; Ishiwatari, Hirotoshi; Matsubayashi, Hiroyuki; Ono, Hiroyuki

    2017-06-01

    In colorectal cancer surgery, inadvertent deep injections during endoscopic tattooing can cause India ink leakage into the peritoneum, leading to complications or to poor visualization of the surgical plane. This ex vivo animal study compared the use of novel shorter, minimum caliber needles versus conventional injection needles for endoscopic tattooing. Four endoscopists used the novel needles and conventional needles to make ten endoscopic tattoos (five tattoos/needle type/endoscopist) in harvested porcine rectum using a saline test-injection method. India ink leakage and the success of the tattoo (i. e. visible, tattoos but for none of the novel needle tattoos ( P  = 0.02). Tattoos created using the novel needles were more successful than those made with the conventional needles: 18/20 (90 %) vs. 11/20 (55 %); P  = 0.01. The use of novel shorter minimum caliber needles may be safe and effective for endoscopic tattooing for preoperative localization prior to colorectal cancer surgery.

  1. Wavelength tuning of porous silicon microcavities

    International Nuclear Information System (INIS)

    Mulders, J.; Reece, P.; Zheng, W.H.; Lerondel, G.; Sun, B.; Gal, M.

    2002-01-01

    Full text: In the last decade much attention has been given to porous silicon (PS) for optoelectronic applications, which include efficient room temperature light emission as well as microcavity formation. Due to the large specific surface area, the use of porous silicon microcavities (PSMs) has been proposed for chemical sensing. Large wavelength shifts have indicated that the optical properties of PSMs are indeed strongly dependent on the environment. In this paper, we report the shifting of the resonance frequency of high quality PSMs, with the aim of tuning a future PS device to a certain required wavelength. The PSM samples were prepared by anodically etching p + -doped (5mΩcm) bulk silicon wafer in a solution (25%) of aqueous HF and ethanol. The device structure consisted of a PS layer sandwiched between 2 stacks of thin PS layers with alternating high and low effective refractive indices (RI), i.e. distributed Bragg mirrors (DBM). The layer thickness depends on the etch time while the porosity and hence refractive index is determined by the current density as the Si is etched. The position and the width of the stop-band can be fully controlled by the design of the DBMs, with the microcavity resonance mode sitting within the stop-band. We achieved tuning of the microcavity resonance by a number of methods, including temperature dependent tuning. The temperature induced wavelength shift was found to be of the order of 10 -15 nm. Computer modeling of these changes in the reflectivity spectra allowed us to quantify the changes of the effective refractive index and the respective layer thicknesses

  2. A radiation research apparatus sensitive to wavelength

    International Nuclear Information System (INIS)

    1980-01-01

    The apparatus described is equipped with a radiation source with a tuning device for the generation of X radiation of at least two different wavelength spectra. The detector with ionisation chamber is able to discriminate between these spectra. This is done with the aid of an auxillary electrode between the entrance window and a high voltage electrode. With a lower source of voltage this electrode has a potential equal to the high voltage electrode potential and with a higher voltage source it has a potential equal to the signal electrode potential. (Th.P.)

  3. Wavelength-agnostic WDM-PON System

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael; Zou, S.

    2016-01-01

    on the standardization status of this lowcost system in the new ITU-T G.metro draft recommendation, in the context of autonomous tuning. We also discuss some low-effort implementations of the pilot-tone labels and investigate the impact of these labels on the transmission channels.......Next-generation WDM-PON solutions for metro and access systems will take advantage of remotely controlled wavelength-tunable ONUs to keep system costs as low as possible. For such a purpose, each ONU signal can be labeled by a pilot tone modulated onto the optical data stream. We report...

  4. Sub-wavelength imaging at radio frequency

    International Nuclear Information System (INIS)

    Wiltshire, M C K; Pendry, J B; Hajnal, J V

    2006-01-01

    A slab of material with a negative permeability can act as a super-lens for magnetic fields and generate images with a sub-wavelength resolution. We have constructed an effective medium using a metamaterial with negative permeability in the region of 24 MHz, and used this to form images in free space of radio frequency magnetic sources. Measurements of these images show that a resolution of approximately λ/64 has been achieved, consistent with both analytical and numerical predictions. (letter to the editor)

  5. Gold Photoluminescence: Wavelength and Polarization Engineering

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Pors, Anders Lambertus; Bozhevolnyi, Sergey I.

    2015-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes...... and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we...

  6. Wavelength converter placement in optical networks with dynamic traffic

    DEFF Research Database (Denmark)

    Buron, Jakob Due; Ruepp, Sarah Renée; Wessing, Henrik

    2008-01-01

    We evaluate the connection provisioning performance of GMPLS-controlled wavelength routed networks under dynamic traffic load and using three different wavelength converter placement heuristics. Results show that a simple uniform placement heuristic matches the performance of complex heuristics...

  7. At least 10% shorter C–H bonds in cryogenic protein crystal structures than in current AMBER forcefields

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Yuan-Ping, E-mail: pang@mayo.edu

    2015-03-06

    High resolution protein crystal structures resolved with X-ray diffraction data at cryogenic temperature are commonly used as experimental data to refine forcefields and evaluate protein folding simulations. However, it has been unclear hitherto whether the C–H bond lengths in cryogenic protein structures are significantly different from those defined in forcefields to affect protein folding simulations. This article reports the finding that the C–H bonds in high resolution cryogenic protein structures are 10–14% shorter than those defined in current AMBER forcefields, according to 3709 C–H bonds in the cryogenic protein structures with resolutions of 0.62–0.79 Å. Also, 20 all-atom, isothermal–isobaric, 0.5-μs molecular dynamics simulations showed that chignolin folded from a fully-extended backbone formation to the native β-hairpin conformation in the simulations using AMBER forcefield FF12SB at 300 K with an aggregated native state population including standard error of 10 ± 4%. However, the aggregated native state population with standard error reduced to 3 ± 2% in the same simulations except that C–H bonds were shortened by 10–14%. Furthermore, the aggregated native state populations with standard errors increased to 35 ± 3% and 26 ± 3% when using FF12MC, which is based on AMBER forcefield FF99, with and without the shortened C–H bonds, respectively. These results show that the 10–14% bond length differences can significantly affect protein folding simulations and suggest that re-parameterization of C–H bonds according to the cryogenic structures could improve the ability of a forcefield to fold proteins in molecular dynamics simulations. - Highlights: • Cryogenic crystal structures are commonly used in computational studies of proteins. • C–H bonds in the cryogenic structures are shorter than those defined in forcefields. • A survey of 3709 C–H bonds shows that the cryogenic bonds are 10–14% shorter. • The

  8. Passively synchronized dual-wavelength Q-switched lasers

    DEFF Research Database (Denmark)

    Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

    We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG.......We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

  9. Meter-wavelength VLBI. III. Pulsars

    International Nuclear Information System (INIS)

    Vandenberg, N.R.; Clark, T.A.; Clark, W.C.; Erickson, W.C.; Resch, G.M.; Broderick, J.J.

    1976-01-01

    The results and analysis of observations of pulsars, especially the Crab Nebula pulsar, taken during a series of meter-wavelength very long baseline interferometry (VLBI) experiments are discussed. Based on a crude 144 MHz visibility curve which is consistent with a Gaussian brightness distribution, the measured visibilities at 196, 111, and 74 MHz were interpreted to yield apparent angular diameters (at half-power) of 0 .03 +- 0 .01, 0 .07 +- 0 .01, and 0 .18 +- 0 .01, respectively. These sizes scale approximately as wavelength-squared, and the 74 MHz size agrees with recent observations using interplanetary scintillation techniques.The VLBI-measured total flux densities lie on the extrapolation from higher frequencies of the pulsing flux densities. Variations in the total flux density up to 25 percent were observed. A lack of fine structure other than the pulsar in the nebula is indicated by our simple visibility curves. The pulse shapes observed with the interferometer are similar to single-dish measurements at 196 MHz but reveal a steady, nonpulsing component at 111 MHz. The ratio of pulsing to total power was approximately equal to one-half but varied with time. No pulsing power was detected at 74 MHz. It was found that four strong, low-dispersion pulsars were only slightly resolved

  10. Coherence techniques at extreme ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chang [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on coherence propagation of an EUV undulator beamline. A numerical simulation based on the Huygens-Fresnel principle is performed.

  11. Observation of magnon-phonon interaction at short wavelengths

    International Nuclear Information System (INIS)

    Dolling, G.; Cowley, R.A.

    1966-01-01

    Measurements have been made of the magnon and phonon dispersion relations in uranium dioxide at 9 o K. These measurements provide evidence of a strong interaction between the magnon and phonon excitations and enable a value to be deduced for the coupling constant. The interaction of long-wavelength magnons in ferromagnetic materials has been studied previously with ultrasonic techniques; however, inelastic scattering of slow neutrons enables both the magnon and phonon dispersion relations to be determined for short wavelengths. In those magnetic materials which have been studied by earlier workers, the magnons and phonons either interacted with one another very weakly or else their frequencies were very different. The results could then be understood without introducing any magnon-phonon interaction. In this note we report measurements of both the magnon and the phonon spectra of antiferromagnetic uranium dioxide, which lead to a magnon-phonon coupling constant of 9.6 ± 1.6 o K. Since the Neel temperature is 30.8 o K, this coupling constant is of a similar magnitude to the direct magnetic interactions. (author)

  12. A Kinetic Model Explains Why Shorter and Less Affine Enzyme-recruiting Oligonucleotides Can Be More Potent

    Directory of Open Access Journals (Sweden)

    Lykke Pedersen

    2014-01-01

    Full Text Available Antisense oligonucleotides complementary to RNA targets promise generality and ease of drug design. The first systemically administered antisense drug was recently approved for treatment and others are in clinical development. Chemical modifications that increase the hybridization affinity of oligonucleotides are reasoned to confer higher potency, i.e., modified oligonucleotides can be dosed at lower concentrations to achieve the same effect. Surprisingly, shorter and less affine oligonucleotides sometimes display increased potency. To explain this apparent contradiction, increased uptake or decreased propensity to form structures have been suggested as possible mechanisms. Here, we provide an alternative explanation that invokes only the kinetics behind oligonucleotide-mediated cleavage of RNA targets. A model based on the law of mass action predicts, and experiments support, the existence of an optimal binding affinity. Exaggerated affinity, and not length per se, is detrimental to potency. This finding clarifies how to optimally apply high-affinity modifications in the discovery of potent antisense oligonucleotide drugs.

  13. WDM cross-connect cascade based on all-optical wavelength converters for routing and wavelength slot interchanging using a reduced number of internal wavelengths

    DEFF Research Database (Denmark)

    Pedersen, Rune Johan Skullerud; Mikkelsen, Benny; Jørgensen, Bo Foged

    1998-01-01

    interchanging can be used to create a robust and nonblocking OXC. However, for an OXC with n fiber inlets each carrying m wavelengths the OXC requires n×m internal wavelengths, which constrains the size of the cross-connect. In this paper we therefore propose and demonstrate an architecture that uses a reduced......Optical transport layers need rearrangeable wavelength-division multiplexing optical cross-connects (OXCs) to increase the capacity and flexibility of the network. It has previously been shown that a cross-connect based on all-optical wavelength converters for routing as well as wavelength slot...... set of internal wavelengths without sacrificing cross-connecting capabilities. By inserting a partly equipped OXC with the new architecture in a 10-Gbit/s re-circulating loop setup we demonstrate the possibility of cascading up to ten OXCs. Furthermore, we investigate the regenerating effect...

  14. The association between post-traumatic stress disorder and shorter telomere length: A systematic review and meta-analysis.

    Science.gov (United States)

    Li, Xuemei; Wang, Jiang; Zhou, Jianghua; Huang, Pan; Li, Jiping

    2017-08-15

    Post-traumatic stress disorder (PTSD) is a common psychiatric disorder, which may accelerate aging. Many study have investigated the association between telomeres length and PTSD, but results from published studies are contradictory. Therefore, Meta-analysis approaches were conducted to give more precise estimate of relationship between telomere length and PTSD. We systematically reviewed the databases of PUBMED, PsycINFO, Medline(Ovid SP) and EMBASE for all articles on the association between telomere length and PTSD. Data were summarized by using random-effects in the meta-analysis. The heterogeneity among studies were examined by using Cochrane's Q statistic and I-squared. Five eligible studies containing 3851 participants were included in our meta-analysis. Shorten telomere length was significantly associated with PTSD with mean difference of -0.19( 95% CI: -0.27, -0.01; P<0.001) with I-square of 96%. The results from subgroup analysis demonstrated that shorter telomere length was significantly associated with PTSD across all gender groups, with mean difference of -0.15( 95% CI: -0.29, -0.01; P=0.04) for female, mean difference of -0.17( 95% CI: -0.19, -0.15; P<0.001) for male. Meanwhile, shorten telomere length was significantly associated with sexual assault(mean difference =-0.15, 95% CI: -0.29, -0.01), childhood trauma (mean difference =-0.08, 95% CI: -0.19, -0.07), but not combat (mean difference =-0.39, 95% CI: -0.83, 0.05). Compared to the individuals without PTSD, individuals with PTSD have shorter telomere length, which has implications for early intervention and timely treatment to prevent future adverse health outcomes. Copyright © 2017. Published by Elsevier B.V.

  15. Objective identification of informative wavelength regions in galaxy spectra

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Ching-Wa; Szalay, Alexander S.; Budavári, Tamás; Wyse, Rosemary F. G. [Department of Physics and Astronomy, The Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218 (United States); Mahoney, Michael W. [Department of Mathematics, Stanford University, Stanford, CA 94305 (United States); Csabai, István; Dobos, Laszlo, E-mail: cwyip@pha.jhu.edu, E-mail: szalay@jhu.edu, E-mail: mmahoney@cs.stanford.edu [Department of Physics of Complex Systems, Eötvös Loránd University, H-1117 Budapest (Hungary)

    2014-05-01

    Understanding the diversity in spectra is the key to determining the physical parameters of galaxies. The optical spectra of galaxies are highly convoluted with continuum and lines that are potentially sensitive to different physical parameters. Defining the wavelength regions of interest is therefore an important question. In this work, we identify informative wavelength regions in a single-burst stellar population model using the CUR Matrix Decomposition. Simulating the Lick/IDS spectrograph configuration, we recover the widely used D {sub n}(4000), Hβ, and Hδ {sub A} to be most informative. Simulating the Sloan Digital Sky Survey spectrograph configuration with a wavelength range 3450-8350 Å and a model-limited spectral resolution of 3 Å, the most informative regions are: first region—the 4000 Å break and the Hδ line; second region—the Fe-like indices; third region—the Hβ line; and fourth region—the G band and the Hγ line. A principal component analysis on the first region shows that the first eigenspectrum tells primarily the stellar age, the second eigenspectrum is related to the age-metallicity degeneracy, and the third eigenspectrum shows an anti-correlation between the strengths of the Balmer and the Ca K and H absorptions. The regions can be used to determine the stellar age and metallicity in early-type galaxies that have solar abundance ratios, no dust, and a single-burst star formation history. The region identification method can be applied to any set of spectra of the user's interest, so that we eliminate the need for a common, fixed-resolution index system. We discuss future directions in extending the current analysis to late-type galaxies. ASCII formatted tables of the regional eigenspectra are available.

  16. Progesterone-releasing devices for cattle estrus induction and synchronization: Device optimization to anticipate shorter treatment durations and new device developments.

    Science.gov (United States)

    de Graaff, W; Grimard, B

    2018-05-01

    Synchronization programs using progesterone-releasing intravaginal devices that allow for fixed time artificial insemination are still finding increasing application in bovine reproduction. This practice is useful for rationalizing livestock management because an increased number of cows can be inseminated in one session without the need for estrus detection. Although much of the innovation related to the design and development of intravaginal devices for use in cattle took place in the previous century, progress in understanding the physiology of the bovine estrous cycle resulted in shorter treatment durations, a trend which is still continuing. In this competitive market, with little functional differentiation between the existing devices, the shorter treatment duration prompted for optimization of the progesterone content in the device, as the cost of the drug significantly contributes to the price per unit. For CIDR ® a reduction of the progesterone content of about 30 per cent was realized. Price reduction remained an important target for further device development. Next to reduction of progesterone content, cheaper and easier to process materials like polyethylene vinyl acetate (EVA) copolymers have been explored to replace the commonly used silicone elastomers. The reengineering effort of CIDR ® demonstrated that knowledge of release kinetics and insight into gradual depletion patterns in the device is critical for optimization of drug content without compromising performance (blood levels). More recent publications related to the use of alternative polymers like EVA and polyisoprene (IP) indicated encouraging results regarding further reduction of progesterone content. The use of EVA seems most promising, because it is in principle a low-cost polymer available in many grades and this thermoplastic polymer can be processed easily by means of commonly used techniques like injection molding and extrusion. The use of thermoplastic polymers, however, requires

  17. Dynamic Sensor Interrogation Using Wavelength-Swept Laser with a Polygon-Scanner-Based Wavelength Filter

    Science.gov (United States)

    Kwon, Yong Seok; Ko, Myeong Ock; Jung, Mi Sun; Park, Ik Gon; Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Park, Kyung Hyun; Jeon, Min Yong

    2013-01-01

    We report a high-speed (∼2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement. PMID:23899934

  18. Temperature Characteristics of Monolithically Integrated Wavelength-Selectable Light Sources

    International Nuclear Information System (INIS)

    Han Liang-Shun; Zhu Hong-Liang; Zhang Can; Ma Li; Liang Song; Wang Wei

    2013-01-01

    The temperature characteristics of monolithically integrated wavelength-selectable light sources are experimentally investigated. The wavelength-selectable light sources consist of four distributed feedback (DFB) lasers, a multimode interferometer coupler, and a semiconductor optical amplifier. The oscillating wavelength of the DFB laser could be modulated by adjusting the device operating temperature. A wavelength range covering over 8.0nm is obtained with stable single-mode operation by selecting the appropriate laser and chip temperature. The thermal crosstalk caused by the lateral heat spreading between lasers operating simultaneously is evaluated by oscillating-wavelength shift. The thermal crosstalk approximately decreases exponentially as the increasing distance between lasers

  19. Analysis of subsystems in wavelength-division-multiplexing networks

    DEFF Research Database (Denmark)

    Liu, Fenghai

    2001-01-01

    Wavelength division multiplexing (WDM) technology together with optical amplification has created a new era for optical communication. Transmission capacity is greatly increased by adding more and more wavelength channels into a single fiber, as well as by increasing the line rate of each channel...... in semiconductor optical amplifiers (SOAs), and dispersion managed fiber sections. New subsystems are also proposed in the thesis: a modular 2×2 multiwavelength cross-connect using wavelength switching blocks, a wavelength converter based on cross phase modulation in a semiconductor modulator, a wavelength...

  20. Short-wavelength soft-x-ray laser pumped in double-pulse single-beam non-normal incidence

    International Nuclear Information System (INIS)

    Zimmer, D.; Ros, D.; Guilbaud, O.; Habib, J.; Kazamias, S.; Zielbauer, B.; Bagnoud, V.; Ecker, B.; Aurand, B.; Kuehl, T.; Hochhaus, D. C.; Neumayer, P.

    2010-01-01

    We demonstrated a 7.36 nm Ni-like samarium soft-x-ray laser, pumped by 36 J of a neodymium:glass chirped-pulse amplification laser. Double-pulse single-beam non-normal-incidence pumping was applied for efficient soft-x-ray laser generation. In this case, the applied technique included a single-optic focusing geometry for large beam diameters, a single-pass grating compressor, traveling-wave tuning capability, and an optimized high-energy laser double pulse. This scheme has the potential for even shorter-wavelength soft-x-ray laser pumping.

  1. Underdense radiation sources: Moving towards longer wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Back, C.A.; Kilkenny, J.D. [General Atomics, San Diego, California (United States); Seely, J.F.; Weaver, J.L. [Naval Research Laboratory, Washington, DC (United States); Feldman, U. [Artep Inc., Ellicott City, MD (United States); Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A. [Lawrence Livermore National Laboratory, California (United States); Tillack, M. [U. C. San Diego, La Jolla, CA (United States)

    2006-06-15

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO{sub 2} aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  2. Underdense radiation sources: Moving towards longer wavelengths

    International Nuclear Information System (INIS)

    Back, C.A.; Kilkenny, J.D.; Seely, J.F.; Weaver, J.L.; Feldman, U.; Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A.; Tillack, M.

    2006-01-01

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO 2 aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  3. Spin and wavelength multiplexed nonlinear metasurface holography

    Science.gov (United States)

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-06-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

  4. Aligning of single and multiple wavelength chromatographic

    DEFF Research Database (Denmark)

    Nielsen, Niels-Peter Vest; Carstensen, Jens Michael; Smedsgaard, Jørn

    1998-01-01

    optimised warping (COW) using two input parameters which can be estimated from the observed peak width. COW is demonstrated on constructed single trace chromatograms and on single and multiple wavelength chromatograms obtained from HPLC diode detection analyses of fungal extractsA copy of the C program......The use of chemometric data processing is becoming an important part of modern chromatography. Most chemometric analyses are performed on reduced data sets using areas of selected peaks detected in the chromatograms, which means a loss of data and introduces the problem of extracting peak data from...... to utilise the entire data matrix or rely on peak detection, thus having the same limitations as the commonly used chemometric procedures. The method presented uses the entire chromatographic data matrices and does not require any preprocessing e.g., peak detection. It relies on piecewise linear correlation...

  5. Self Referencing Heterodyne Transient Grating Spectroscopy with Short Wavelength

    Directory of Open Access Journals (Sweden)

    Jakob Grilj

    2015-04-01

    Full Text Available Heterodyning by a phase stable reference electric field is a well known technique to amplify weak nonlinear signals. For short wavelength, the generation of a reference field in front of the sample is challenging because of a lack of suitable beamsplitters. Here, we use a permanent grating which matches the line spacing of the transient grating for the creation of a phase stable reference field. The relative phase among the two can be changed by a relative translation of the permanent and transient gratings in direction orthogonal to the grating lines. We demonstrate the technique for a transient grating on a VO2 thin film and observe constructive as well as destructive interference signals.

  6. The Change of the Family Life Affected by the Shorter Working Time : From the Point of View of the Home Management

    OpenAIRE

    平田, 道憲

    1994-01-01

    In Japan, the working time has been decreasing. However, Japanese working people spend more hours per year to work than those in Western countries. The policy of the shorter working time is conducted by the Japanese Government in order that the working people get more free time. This paper examines whether the shorter working time of working members in the family enrich the time use of the other members of the family. Especially, the effect of the shorter working time of husbands to wives...

  7. Wavelength-stepped, actively mode-locked fiber laser based on wavelength-division-multiplexed optical delay lines

    Science.gov (United States)

    Lee, Eunjoo; Kim, Byoung Yoon

    2017-12-01

    We propose a new scheme for an actively mode-locked wavelength-swept fiber laser that produces a train of discretely wavelength-stepped pulses from a short fiber cavity. Pulses with different wavelengths are split and combined by standard wavelength division multiplexers with fiber delay lines. As a proof of concept, we demonstrate a laser using an erbium doped fiber amplifier and commercially available wavelength-division multiplexers with wavelength spacing of 0.8 nm. The results show simultaneous mode-locking at three different wavelengths. Laser output parameters in time domain, optical and radio frequency spectral domain, and the noise characteristics are presented. Suggestions for the improved design are discussed.

  8. High-accuracy measurements of snow Bidirectional Reflectance Distribution Function at visible and NIR wavelengths – comparison with modelling results

    Directory of Open Access Journals (Sweden)

    M. Dumont

    2010-03-01

    Full Text Available High-accuracy measurements of snow Bidirectional Reflectance Distribution Function (BRDF were performed for four natural snow samples with a spectrogonio-radiometer in the 500–2600 nm wavelength range. These measurements are one of the first sets of direct snow BRDF values over a wide range of lighting and viewing geometry. They were compared to BRDF calculated with two optical models. Variations of the snow anisotropy factor with lighting geometry, wavelength and snow physical properties were investigated. Results show that at wavelengths with small penetration depth, scattering mainly occurs in the very top layers and the anisotropy factor is controlled by the phase function. In this condition, forward scattering peak or double scattering peak is observed. In contrast at shorter wavelengths, the penetration of the radiation is much deeper and the number of scattering events increases. The anisotropy factor is thus nearly constant and decreases at grazing observation angles. The whole dataset is available on demand from the corresponding author.

  9. Elevated CD147 expression is associated with shorter overall survival in non-small cell lung cancer.

    Science.gov (United States)

    Zhang, Xiaojun; Tian, Tian; Zhang, Xiaofeng; Liu, Changting; Fang, Xiangqun

    2017-06-06

    A number of studies have reported on the prognostic role of CD147 expression in non-small cell lung cancer (NSCLC); however, the results remain controversial. This study aims to investigate the impact of CD147 on the prognosis of NSCLC by means of a meta-analysis. A literature search was performed for relevant studies published before October 29, 2016. The hazard ratios (HRs), odds ratios (ORs), and 95% confidence intervals (CIs) were calculated as effective measures. Sensitivity analysis and publication bias examination were also conducted. Ten eligible studies with a total of 1605 patients were included in this meta-analysis. CD147 overexpression was correlated with poor overall survival (OS) (HR=1.59, 95% CI=1.32-1.91, pCD147 expression was associated with the presence of lymph node metastasis (OR=2.31, 95% CI=1.74-3.07, pCD147 and sex, age, differentiation, or histology was found. No evidence of significant publication bias was identified. This meta-analysis revealed that overexpression of CD147 was associated with shorter OS, the presence of lymph node metastasis and advanced TNM stage in NSCLC. Therefore, CD147 could serve as a potential prognostic marker for NSCLC.

  10. Dyslexics' faster decay of implicit memory for sounds and words is manifested in their shorter neural adaptation.

    Science.gov (United States)

    Jaffe-Dax, Sagi; Frenkel, Or; Ahissar, Merav

    2017-01-24

    Dyslexia is a prevalent reading disability whose underlying mechanisms are still disputed. We studied the neural mechanisms underlying dyslexia using a simple frequency-discrimination task. Though participants were asked to compare the two tones in each trial, implicit memory of previous trials affected their responses. We hypothesized that implicit memory decays faster among dyslexics. We tested this by increasing the temporal intervals between consecutive trials, and by measuring the behavioral impact and ERP responses from the auditory cortex. Dyslexics showed a faster decay of implicit memory effects on both measures, with similar time constants. Finally, faster decay of implicit memory also characterized the impact of sound regularities in benefitting dyslexics' oral reading rate. Their benefit decreased faster as a function of the time interval from the previous reading of the same non-word. We propose that dyslexics' shorter neural adaptation paradoxically accounts for their longer reading times, since it reduces their temporal window of integration of past stimuli, resulting in noisier and less reliable predictions for both simple and complex stimuli. Less reliable predictions limit their acquisition of reading expertise.

  11. Shorter duration of non-rapid eye movement sleep slow waves in EphA4 knockout mice.

    Science.gov (United States)

    Freyburger, Marlène; Poirier, Gaétan; Carrier, Julie; Mongrain, Valérie

    2017-10-01

    Slow waves occurring during non-rapid eye movement sleep have been associated with neurobehavioural performance and memory. In addition, the duration of previous wakefulness and sleep impacts characteristics of these slow waves. However, molecular mechanisms regulating the dynamics of slow-wave characteristics remain poorly understood. The EphA4 receptor regulates glutamatergic transmission and synaptic plasticity, which have both been linked to sleep slow waves. To investigate if EphA4 regulates slow-wave characteristics during non-rapid eye movement sleep, we compared individual parameters of slow waves between EphA4 knockout mice and wild-type littermates under baseline conditions and after a 6-h sleep deprivation. We observed that, compared with wild-type mice, knockout mice display a shorter duration of positive and negative phases of slow waves under baseline conditions and after sleep deprivation. However, the mutation did not change slow-wave density, amplitude and slope, and did not affect the sleep deprivation-dependent changes in slow-wave characteristics, suggesting that EphA4 is not involved in the response to elevated sleep pressure. Our present findings suggest a role for EphA4 in shaping cortical oscillations during sleep that is independent from sleep need. © 2017 European Sleep Research Society.

  12. Alternative promoter usage generates novel shorter MAPT mRNA transcripts in Alzheimer's disease and progressive supranuclear palsy brains.

    Science.gov (United States)

    Huin, Vincent; Buée, Luc; Behal, Hélène; Labreuche, Julien; Sablonnière, Bernard; Dhaenens, Claire-Marie

    2017-10-03

    Alternative promoter usage is an important mechanism for transcriptome diversity and the regulation of gene expression. Indeed, this alternative usage may influence tissue/subcellular specificity, protein translation and function of the proteins. The existence of an alternative promoter for MAPT gene was considered for a long time to explain differential tissue specificity and differential response to transcription and growth factors between mRNA transcripts. The alternative promoter usage could explain partly the different tau proteins expression patterns observed in tauopathies. Here, we report on our discovery of a functional alternative promoter for MAPT, located upstream of the gene's second exon (exon 1). By analyzing genome databases and brain tissue from control individuals and patients with Alzheimer's disease or progressive supranuclear palsy, we identified novel shorter transcripts derived from this alternative promoter. These transcripts are increased in patients' brain tissue as assessed by 5'RACE-PCR and qPCR. We suggest that these new MAPT isoforms can be translated into normal or amino-terminal-truncated tau proteins. We further suggest that activation of MAPT's alternative promoter under pathological conditions leads to the production of truncated proteins, changes in protein localization and function, and thus neurodegeneration.

  13. Cleavage of SNAP25 and its shorter versions by the protease domain of serotype A botulinum neurotoxin.

    Directory of Open Access Journals (Sweden)

    Rahman M Mizanur

    Full Text Available Various substrates, catalysts, and assay methods are currently used to screen inhibitors for their effect on the proteolytic activity of botulinum neurotoxin. As a result, significant variation exists in the reported results. Recently, we found that one source of variation was the use of various catalysts, and have therefore evaluated its three forms. In this paper, we characterize three substrates under near uniform reaction conditions using the most active catalytic form of the toxin. Bovine serum albumin at varying optimum concentrations stimulated enzymatic activity with all three substrates. Sodium chloride had a stimulating effect on the full length synaptosomal-associated protein of 25 kDa (SNAP25 and its 66-mer substrates but had an inhibitory effect on the 17-mer substrate. We found that under optimum conditions, full length SNAP25 was a better substrate than its shorter 66-mer or 17-mer forms both in terms of kcat, Km, and catalytic efficiency kcat/Km. Assay times greater than 15 min introduced large variations and significantly reduced the catalytic efficiency. In addition to characterizing the three substrates, our results identify potential sources of variations in previous published results, and underscore the importance of using well-defined reaction components and assay conditions.

  14. Shorter time since inflammatory bowel disease diagnosis in children is associated with lower mental health in parents.

    Science.gov (United States)

    Werner, H; Braegger, Cp; Buehr, P; Koller, R; Nydegger, A; Spalinger, J; Heyland, K; Schibli, S; Landolt, Ma

    2015-01-01

    This study assessed the mental health of parents of children with inflammatory bowel disease (IBD), compared their mental health with age-matched and gender-matched references and examined parental and child predictors for mental health problems. A total of 125 mothers and 106 fathers of 125 children with active and inactive IBD from the Swiss IBD multicentre cohort study were included. Parental mental health was assessed by the Symptom Checklist 27 and child behaviour problems by the Strengths and Difficulties Questionnaire. Child medical data were extracted from hospital records. While the mothers reported lower mental health, the fathers' mental health was similar, or even better, than in age-matched and gender-matched community controls. In both parents, shorter time since the child's diagnosis was associated with poorer mental health. In addition, the presence of their own IBD diagnosis and child behaviour problems predicted maternal mental health problems. Parents of children with IBD may need professional support when their child is diagnosed, to mitigate distress. This, in turn, may help the child to adjust better to IBD. Particular attention should be paid to mothers who have their own IBD diagnosis and whose children display behaviour problems. ©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  15. SHORTER, Aylward. African recruits and missionary conscripts: the White Fathers and the Great War (1914 – 1922. London: Missionaries of Africa History Project, 2007. 270 p. ISBN: 9780955523502

    Directory of Open Access Journals (Sweden)

    Jefferson Olivatto da Silva

    2011-09-01

    Full Text Available Resenha do livroSHORTER, Aylward. African recruits and missionary conscripts: the White Fathers and the Great War (1914 – 1922. London: Missionaries of Africa History Project, 2007. 270 p. ISBN: 9780955523502

  16. Metasurface axicon lens design at visible wavelengths

    Science.gov (United States)

    Alyammahi, Saleimah; Zhan, Qiwen

    2017-08-01

    The emerging field of metasurfaces is promising to realize novel optical devices with miniaturized flat format and added functionalities. Metasurfaces have been demonstrated to exhibit full control of amplitude, phase and polarization of electromagnetic waves. Using the metasurface, the wavefront of light can be manipulated permitting new functionalities such as focusing and steering of the beams and imaging. One optical component which can be designed using metasurfaces is the axicon. Axicons are conical lenses used to convert Gaussian beams into nondiffraction Bessel beams. These unique devices are utilized in different applications ranging from optical trapping and manipulation, medical imaging, and surgery. In this work, we study axicon lens design comprising of planar metasurfaces which generate non-diffracting Bessel beams at visible wavelengths. Dielectric metasurfaces have been used to achieve high efficiency and low optical loss. We measured the spot size of the resulted beams at different planes to demonstrate the non-diffraction properties of the resulted beams. We also investigated how the spot size is influenced by the axicon aperture. Furthermore, we examined the achromatic properties of the designed axicon. Comparing with the conventional lens, the metasurface axicon lens design enables the creation of flat optical device with wide range of depth of focus along its optical axis.

  17. Photoemission electron microscopy of localized surface plasmons in silver nanostructures at telecommunication wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Mårsell, Erik; Larsen, Esben W.; Arnold, Cord L.; Xu, Hongxing; Mauritsson, Johan; Mikkelsen, Anders, E-mail: anders.mikkelsen@sljus.lu.se [Department of Physics, Lund University, P.O. Box 118, 22 100 Lund (Sweden)

    2015-02-28

    We image the field enhancement at Ag nanostructures using femtosecond laser pulses with a center wavelength of 1.55 μm. Imaging is based on non-linear photoemission observed in a photoemission electron microscope (PEEM). The images are directly compared to ultra violet PEEM and scanning electron microscopy (SEM) imaging of the same structures. Further, we have carried out atomic scale scanning tunneling microscopy on the same type of Ag nanostructures and on the Au substrate. Measuring the photoelectron spectrum from individual Ag particles shows a larger contribution from higher order photoemission processes above the work function threshold than would be predicted by a fully perturbative model, consistent with recent results using shorter wavelengths. Investigating a wide selection of both Ag nanoparticles and nanowires, field enhancement is observed from 30% of the Ag nanoparticles and from none of the nanowires. No laser-induced damage is observed of the nanostructures neither during the PEEM experiments nor in subsequent SEM analysis. By direct comparison of SEM and PEEM images of the same nanostructures, we can conclude that the field enhancement is independent of the average nanostructure size and shape. Instead, we propose that the variations in observed field enhancement could originate from the wedge interface between the substrate and particles electrically connected to the substrate.

  18. The return trip is felt shorter only postdictively: A psychophysiological study of the return trip effect [corrected].

    Directory of Open Access Journals (Sweden)

    Ryosuke Ozawa

    Full Text Available The return trip often seems shorter than the outward trip even when the distance and actual time are identical. To date, studies on the return trip effect have failed to confirm its existence in a situation that is ecologically valid in terms of environment and duration. In addition, physiological influences as part of fundamental timing mechanisms in daily activities have not been investigated in the time perception literature. The present study compared round-trip and non-round-trip conditions in an ecological situation. Time estimation in real time and postdictive estimation were used to clarify the situations where the return trip effect occurs. Autonomic nervous system activity was evaluated from the electrocardiogram using the Lorenz plot to demonstrate the relationship between time perception and physiological indices. The results suggest that the return trip effect is caused only postdictively. Electrocardiographic analysis revealed that the two experimental conditions induced different responses in the autonomic nervous system, particularly in sympathetic nervous function, and that parasympathetic function correlated with postdictive timing. To account for the main findings, the discrepancy between the two time estimates is discussed in the light of timing strategies, i.e., prospective and retrospective timing, which reflect different emphasis on attention and memory processes. Also each timing method, i.e., the verbal estimation, production or comparative judgment, has different characteristics such as the quantification of duration in time units or knowledge of the target duration, which may be responsible for the discrepancy. The relationship between postdictive time estimation and the parasympathetic nervous system is also discussed.

  19. Wavelength encoding technique for particle analyses in hematology analyzer

    Science.gov (United States)

    Rongeat, Nelly; Brunel, Patrick; Gineys, Jean-Philippe; Cremien, Didier; Couderc, Vincent; Nérin, Philippe

    2011-07-01

    The aim of this study is to combine multiple excitation wavelengths in order to improve accuracy of fluorescence characterization of labeled cells. The experimental demonstration is realized with a hematology analyzer based on flow cytometry and a CW laser source emitting two visible wavelengths. A given optical encoding associated to each wavelength allows fluorescence identification coming from specific fluorochromes and avoiding the use of noisy compensation method.

  20. Performance evaluation of distributed wavelength assignment in WDM optical networks

    Science.gov (United States)

    Hashiguchi, Tomohiro; Wang, Xi; Morikawa, Hiroyuki; Aoyama, Tomonori

    2004-04-01

    In WDM wavelength routed networks, prior to a data transfer, a call setup procedure is required to reserve a wavelength path between the source-destination node pairs. A distributed approach to a connection setup can achieve a very high speed, while improving the reliability and reducing the implementation cost of the networks. However, along with many advantages, several major challenges have been posed by the distributed scheme in how the management and allocation of wavelength could be efficiently carried out. In this thesis, we apply a distributed wavelength assignment algorithm named priority based wavelength assignment (PWA) that was originally proposed for the use in burst switched optical networks to the problem of reserving wavelengths of path reservation protocols in the distributed control optical networks. Instead of assigning wavelengths randomly, this approach lets each node select the "safest" wavelengths based on the information of wavelength utilization history, thus unnecessary future contention is prevented. The simulation results presented in this paper show that the proposed protocol can enhance the performance of the system without introducing any apparent drawbacks.

  1. Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

    DEFF Research Database (Denmark)

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron

    2014-01-01

    numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model...... is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken...

  2. Span Restoration in Optical Networks with Limited Wavelength Conversion

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Buron, Jakob Due; Andriolli, N

    2007-01-01

    Next generation optical networks provide functionalities to dynamically provision and recover connections, while emerging technologies allow for the conversion between wavelengths. These devices are however expensive and hence it is likely that only few are deployed throughout the network...... converter-saving wavelength assignment in GMPLS networks. The converter saving property of the Suggested Vector is particularly desirable in span restoration, where the pre-failure path stubs have to be merged to the restoration path at the failure-adjacent nodes. In order to avoid wavelength conversion....... Furthermore, we describe different scenarios to extend the suggested vector wavelength assignment scheme to multi-domain networks with focus on span restoration....

  3. A new diagnostic for the tritium phase of JET covering the visible and UV wavelength range

    International Nuclear Information System (INIS)

    Morsi, H.W.; Hatzky, R.; Hellermann, M. von

    1991-01-01

    The objectives of an active-phase direct optical link between the JET tokamak and spectral instruments beyond the biological shield are manifold. The present optical fibre links, which are used as a standard at JET, may be subjected to much enhanced radiation levels in future operations with D-T plasmas, and a direct optical link, based on a system of remotely controllable relay mirrors, will be a vital test for future activated fusion devices. A further aim is to extend the spectral range of exploitable charge exchange (CX) lines to shorter wavelengths, which is presently limited by the transmission of quartz fibres to CX lines above 4000 A. The latter aspect is particularly relevant in the case of HeII where the sole CX line of HeII (n = 4 to 3) in the visible, is superimposed by a BeIV CX line (n = 8 to 6) at the same wavelength (4685 A). This fact constraints the present helium analysis to plasma conditions with n(Be)<0.3·n(He). For future alpha particle studies, especially at low alpha particle densities, this constraint may require either sophisticated analysis procedures or alternatively the use of other less ''disturbed'' lines, possibly in the UV wavelength range. Finally the UV link is intended to provide an optical transfer channel for short optical jumpers to other JET observation ports - for example coherent fibre bundles imaging the X-point strike zone - to the diagnostic instruments in the roof laboratory of JET. (author) 1 ref., 6 figs

  4. Parallel implementation of the PHOENIX generalized stellar atmosphere program. II. Wavelength parallelization

    International Nuclear Information System (INIS)

    Baron, E.; Hauschildt, Peter H.

    1998-01-01

    We describe an important addition to the parallel implementation of our generalized nonlocal thermodynamic equilibrium (NLTE) stellar atmosphere and radiative transfer computer program PHOENIX. In a previous paper in this series we described data and task parallel algorithms we have developed for radiative transfer, spectral line opacity, and NLTE opacity and rate calculations. These algorithms divided the work spatially or by spectral lines, that is, distributing the radial zones, individual spectral lines, or characteristic rays among different processors and employ, in addition, task parallelism for logically independent functions (such as atomic and molecular line opacities). For finite, monotonic velocity fields, the radiative transfer equation is an initial value problem in wavelength, and hence each wavelength point depends upon the previous one. However, for sophisticated NLTE models of both static and moving atmospheres needed to accurately describe, e.g., novae and supernovae, the number of wavelength points is very large (200,000 - 300,000) and hence parallelization over wavelength can lead both to considerable speedup in calculation time and the ability to make use of the aggregate memory available on massively parallel supercomputers. Here, we describe an implementation of a pipelined design for the wavelength parallelization of PHOENIX, where the necessary data from the processor working on a previous wavelength point is sent to the processor working on the succeeding wavelength point as soon as it is known. Our implementation uses a MIMD design based on a relatively small number of standard message passing interface (MPI) library calls and is fully portable between serial and parallel computers. copyright 1998 The American Astronomical Society

  5. A simple wavelength division multiplexing system for active learning teaching

    Science.gov (United States)

    Zghal, Mourad; Ghalila, Hassen; Ben Lakhdar, Zohra

    2009-06-01

    The active learning project consists in a series of workshops for educators, researchers and students and promotes an innovative method of teaching physics using simple, inexpensive materials that can be fabricated locally. The objective of the project is to train trainers and inspire students to learn physics. The workshops are based on the use of laboratory work and hands-on activities in the classroom. The interpretation of these experiments is challenging for some students, and the experiments can lead to a significant amount of discussion. The workshops are organized within the framework of the project ``Active Learning in Optics and Photonics" (ALOP) mainly funded by UNESCO, with the support of ICTP (Abdus Salam International Centre for Theoretical Physics) and SPIE. ALOP workshops offer high school, college or university physics teachers the opportunity to improve their conceptual understanding of optics. These workshops usually run for five days and cover several of the topics usually found in any introductory university physics program. Optics and photonics are used as subject matter because it is relevant as well as adaptable to research and educational conditions in many developing countries [1]. In this paper, we will mainly focus on a specific topic of the ALOP workshops, namely optical communications and Wavelength Division Multiplexing technology (WDM). This activity was originally developed by Mazzolini et al [2]. WDM is a technology used in fibre-optic communications for transmitting two or more separate signals over a single fibre optic cable by using a separate wavelength for each signal. Multiple signals are carried together as separate wavelengths of light in a multiplexed signal. Simple and inexpensive WDM system was implemented in our laboratory using light emitting diodes or diode lasers, plastic optical fibres, a set of optical filters and lenses, prism or grating, and photodiodes. Transmission of audio signals using home-made, simple

  6. Dual wavelength multiple-angle light scattering system for cryptosporidium detection

    Science.gov (United States)

    Buaprathoom, S.; Pedley, S.; Sweeney, S. J.

    2012-06-01

    A simple, dual wavelength, multiple-angle, light scattering system has been developed for detecting cryptosporidium suspended in water. Cryptosporidium is a coccidial protozoan parasite causing cryptosporidiosis; a diarrheal disease of varying severity. The parasite is transmitted by ingestion of contaminated water, particularly drinking-water, but also accidental ingestion of bathing-water, including swimming pools. It is therefore important to be able to detect these parasites quickly, so that remedial action can be taken to reduce the risk of infection. The proposed system combines multiple-angle scattering detection of a single and two wavelengths, to collect relative wavelength angle-resolved scattering phase functions from tested suspension, and multivariate data analysis techniques to obtain characterizing information of samples under investigation. The system was designed to be simple, portable and inexpensive. It employs two diode lasers (violet InGaN-based and red AlGaInP-based) as light sources and silicon photodiodes as detectors and optical components, all of which are readily available. The measured scattering patterns using the dual wavelength system showed that the relative wavelength angle-resolved scattering pattern of cryptosporidium oocysts was significantly different from other particles (e.g. polystyrene latex sphere, E.coli). The single wavelength set up was applied for cryptosporidium oocysts'size and relative refractive index measurement and differential measurement of the concentration of cryptosporidium oocysts suspended in water and mixed polystyrene latex sphere suspension. The measurement results showed good agreement with the control reference values. These results indicate that the proposed method could potentially be applied to online detection in a water quality control system.

  7. Compactly packaged monolithic four-wavelength VCSEL array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport.

    Science.gov (United States)

    Lee, Eun-Gu; Mun, Sil-Gu; Lee, Sang Soo; Lee, Jyung Chan; Lee, Jong Hyun

    2015-01-12

    We report a cost-effective transmitter optical sub-assembly using a monolithic four-wavelength vertical-cavity surface-emitting laser (VCSEL) array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport using the data rate of common public radio interface option 6. The wavelength spacing is achieved using selectively etched cavity control layers and fine current adjustment. The differences in operating current and output power for maintaining the wavelength spacing of four VCSELs are fiber without any dispersion-compensation techniques.

  8. Highly accurate Michelson type wavelength meter that uses a rubidium stabilized 1560 nm diode laser as a wavelength reference

    International Nuclear Information System (INIS)

    Masuda, Shin; Kanoh, Eiji; Irisawa, Akiyoshi; Niki, Shoji

    2009-01-01

    We investigated the accuracy limitation of a wavelength meter installed in a vacuum chamber to enable us to develop a highly accurate meter based on a Michelson interferometer in 1550 nm optical communication bands. We found that an error of parts per million order could not be avoided using famous wavelength compensation equations. Chromatic dispersion of the refractive index in air can almost be disregarded when a 1560 nm wavelength produced by a rubidium (Rb) stabilized distributed feedback (DFB) diode laser is used as a reference wavelength. We describe a novel dual-wavelength self-calibration scheme that maintains high accuracy of the wavelength meter. The method uses the fundamental and second-harmonic wavelengths of an Rb-stabilized DFB diode laser. Consequently, a highly accurate Michelson type wavelength meter with an absolute accuracy of 5x10 -8 (10 MHz, 0.08 pm) over a wide wavelength range including optical communication bands was achieved without the need for a vacuum chamber.

  9. Wavelength comparison for laser induced breakdown spectroscopy caries detection

    Science.gov (United States)

    Amaral, Marcello M.; Raele, Marcus P.; Ana, Patrícia A.; Núñez, Sílvia C.; Zamataro, Claudia B.; Zezell, Denise M.

    2018-02-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a technique capable to perform elemental analyses of a variety of samples, independent of matter state. Other spectroscopy techniques may require a destructive and time-consuming sample preparation. On the other hand, LIBS is a less destructive technique with no (or considerably less) sample preparation, using a relatively simple experimental setup. LIBS also provides a multielement analysis into one single spectrum acquisition, applying a Nd:YAG short-pulsed laser to ensure the stoichiometry between the sample and the generated plasma. LIBS have been applied on the study of carious lesions using a Nd:YAG into its fundamental emission at 1064 nm. It was shown that ratio of P/Ca and Zn/Ca can be used to monitor the cariogenic process. Another minor elements, e.g. C and Cu, associated with bacteria biofilm were also measured with the Nd:YAG laser. The fundamental wavelength emission (1064 nm) of Nd:YAG is coincident with a hydroxyapatite transmission window and it may affect the result. In order to address this issue a study used the second harmonic of the Nd:YAG laser at 532 nm. It was show that it is also possible perform LIBS on carious lesion using the Nd:YAG at 532 nm. However, there is not a work direct comparing the LIBS at 532 nm and 1064 nm for carious lesion detection. So, the aim of this work was to investigate the influence of laser wavelength on the LIBS performance for carious lesion detection. In both cases the carious lesion was detected with the advantage of no interference with hydroxyapatite at 532 nm.

  10. Sub-half-wavelength localization of an atom via trichromatic phase control

    International Nuclear Information System (INIS)

    Xu Jun; Hu Xiangming

    2007-01-01

    We show that the trichromatic manipulation of the absorption spectrum leads to sub-half-wavelength atom localization. In particular, a three-level atom in the Λ configuration is considered, in which one transition is coupled by a trichromatic field with one sideband component being a standing-wave field while the other transition is probed by a weak monochromatic field. By varying the sum of relative phases of the sideband components of the trichromatic field to the central component, the atom is localized in either of the two half-wavelength regions with 50% detecting probability when the absorption spectrum is measured

  11. Long-wavelength instability of periodic flows and whistler waves in electron magnetohydrodynamics

    International Nuclear Information System (INIS)

    Lakhin, V.P.; Levchenko, V.D.

    2003-01-01

    Stability analysis of periodic flows and whistlers with respect to long-wavelength perturbations within the framework of dissipative electron magnetohydrodynamics (EMHD) based on two-scale asymptotic expansion technique is presented. Several types of flows are considered: two-dimensional Kolmogorov-like flow, helical flow, and anisotropic helical flow. It is shown hat the destabilizing effect on the long-wavelength perturbations is due to either the negative resistivity effect related to flow anisotropy or α-like effect to its micro helicity. The criteria of the corresponding instabilities are obtained. Numerical simulations of EMHD equations with the initial conditions corresponding to two types of periodic flows are presented. (author)

  12. Optical fibre Bragg gratings at harmonics of the Bragg wavelength and their sensing properties

    International Nuclear Information System (INIS)

    Collins, Stephen F; Sidiroglou, Fotios; Bal, Harpreet K; Baxter, Greg W; Wade, Scott A

    2013-01-01

    Spectral features in optical fibre Bragg gratings (FBGs) at various harmonics of the Bragg wavelength arise due to saturation of the writing process. Additionally, phase-mask-produced FBGs possess a complex refractive index pattern, producing an extra periodicity equal to the phase-mask periodicity that supplements the desired periodicity of half that of the phase-mask, as shown via differential interference contrast microscopy. Some spectral peaks or dips occur as doublets with a wavelength spacing that depends upon fibre alignment relative to the phase mask. These spectral properties are of importance, as they allow the realization of alternative FBG sensors of various measurands. (paper)

  13. Comparison of wavelength conversion efficiency between silicon waveguide and microring resonator

    DEFF Research Database (Denmark)

    Xiong, Meng; Ding, Yunhong; Ou, Haiyan

    2016-01-01

    Wavelength conversion based on degenerate four-wave mixing (FWM) was demonstrated and compared between silicon nanowire and microring resonator (MRR). 15 dB enhancement of conversion efficiency (CE) with relatively low input pump power (5 mW) was achieved experimentally in an MRR. The impacts...

  14. A New Indicator for Optimal Preprocessing and Wavelengths Selection of Near-Infrared Spectra

    NARCIS (Netherlands)

    Skibsted, E.; Boelens, H.F.M.; Westerhuis, J.A.; Witte, D.T.; Smilde, A.K.

    2004-01-01

    Preprocessing of near-infrared spectra to remove unwanted, i.e., non-related spectral variation and selection of informative wavelengths is considered to be a crucial step prior to the construction of a quantitative calibration model. The standard methodology when comparing various preprocessing

  15. New indicator for optimal preprocessing and wavelength selection of near-infrared spectra

    NARCIS (Netherlands)

    Skibsted, E. T. S.; Boelens, H. F. M.; Westerhuis, J. A.; Witte, D. T.; Smilde, A. K.

    2004-01-01

    Preprocessing of near-infrared spectra to remove unwanted, i.e., non-related spectral variation and selection of informative wavelengths is considered to be a crucial step prior to the construction of a quantitative calibration model. The standard methodology when comparing various preprocessing

  16. Notes on the apparent discordance of pulse oximetry and multi-wavelength haemoglobin photometry

    NARCIS (Netherlands)

    Nijland, R.; Jongsma, H.W.; Nijhuis, J.G.; Oeseburg, Berend; Zijlstra, Willem

    1995-01-01

    Multi-wavelength photometers, blood gas analysers and pulse oximeters are widely used to measure various oxygen-related quantities. The definitions of these quantities are not always correct. This paper gives insight in the various definitions for oxygen quantities. Furthermore, the possible

  17. The Interpretation of Wavelengths and Periods as Measured from Atmospheric Balloons.

    Science.gov (United States)

    de La Torre, Alejandro; Alexander, Pedro

    1995-12-01

    Transformations that take into account the characteristics of balloon motion and wave propagation to infer the `real' wavelengths and frequencies from the `apparent' ones measured during sounding are derived. To estimate the differences that may arise in the observations of internal gravity waves, a statistical relation between their wavelength and period recently found from theory and experiment is applied. It is shown that it may not be possible to determine from each apparent datum a unique real value, because up to four different transformations may be applicable for each experimental datum of wavelength or frequency. However, under certain conditions this ambiguity can be removed. The omission of the appropriate transformation may lead one to seriously misinterpret the data.

  18. Double wavelength differential absorption as a technique for early diagnosis of breast cancer

    Science.gov (United States)

    Liger, Vladimir V.; Zybin, Alexander V.; Niemax, Kay; Kuritsyn, Yuri A.; Bolshov, Mikhail A.

    2005-08-01

    The double-wavelength differential molecular absorption technique with diode lasers is proposed for sensitive detection of functional status of breast tissues. The method is based on the measurement of the transmitted intensity differences of the two beams of diode lasers tuned to selected wavelengths within a broad absorption band of a human breast tissue within 700 - 800 nm spectral range. The strategy for the optimum selection of the diode laser wavelengths and initial adjustment of the detection scheme is developed. The method is demonstrated by the detection of the relative concentrations of two dyes, the optical properties of which are similar to those of a mixture of oxy- and deoxy- hemoglobin. The results of the first clinical tests of the proposed technique are briefly described.

  19. Multiple scattering wavelength dependent backscattering of kaolin dust in the IR: Measurements and theory

    Science.gov (United States)

    Ben-David, Avishai

    1992-01-01

    Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.

  20. Technologies for all-optical wavelength conversion in DWDM networks

    DEFF Research Database (Denmark)

    Wolfson, David; Fjelde, Tina; Kloch, Allan

    2001-01-01

    Different techniques for all-optical wavelength conversion are reviewed and the advantages and disadvantages seen from a system perspective are highlighted. All-optical wavelength conversion will play a major role in making cost-effective network nodes in future high-speed WDM networks, where...

  1. Experimental determination of the slow-neutron wavelength distribution

    DEFF Research Database (Denmark)

    Lebech, Bente; Mikke, K.; Sledziewska-Blocka, D.

    1970-01-01

    Different experiments for determining the slow-neutron wavelength distribution in the region 227-3 meV have been carried out, and the results compared. It is concluded that the slow-neutron wave-length distribution can be determined accurately by elastic scattering on a pure incoherent or a pure...

  2. Emission wavelength of multilayer distributed feedback dye lasers

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron L. C.; Brøkner Christiansen, Mads

    2012-01-01

    Precise emission wavelength modeling is essential for understanding and optimization of distributed feedback (DFB) lasers. An analytical approach for determining the emission wavelength based on setting the propagation constant of the Bragg condition and solving for the resulting slab waveguide m...

  3. Sub-wavelength resonances in polygonal metamaterial cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2008-01-01

    It has been shown that the sub-wavelength resonances of circular MTM cylinders also occur for polygonal MTM cylinders. This is the case for lossless and non-dispersive cylinders as well as lossy and dispersive cylinders. The sub-wavelength resonances are thus not limited to structures of canonical...

  4. Systematic wavelength selection for improved multivariate spectral analysis

    Science.gov (United States)

    Thomas, Edward V.; Robinson, Mark R.; Haaland, David M.

    1995-01-01

    Methods and apparatus for determining in a biological material one or more unknown values of at least one known characteristic (e.g. the concentration of an analyte such as glucose in blood or the concentration of one or more blood gas parameters) with a model based on a set of samples with known values of the known characteristics and a multivariate algorithm using several wavelength subsets. The method includes selecting multiple wavelength subsets, from the electromagnetic spectral region appropriate for determining the known characteristic, for use by an algorithm wherein the selection of wavelength subsets improves the model's fitness of the determination for the unknown values of the known characteristic. The selection process utilizes multivariate search methods that select both predictive and synergistic wavelengths within the range of wavelengths utilized. The fitness of the wavelength subsets is determined by the fitness function F=.function.(cost, performance). The method includes the steps of: (1) using one or more applications of a genetic algorithm to produce one or more count spectra, with multiple count spectra then combined to produce a combined count spectrum; (2) smoothing the count spectrum; (3) selecting a threshold count from a count spectrum to select these wavelength subsets which optimize the fitness function; and (4) eliminating a portion of the selected wavelength subsets. The determination of the unknown values can be made: (1) noninvasively and in vivo; (2) invasively and in vivo; or (3) in vitro.

  5. Sub-wavelength metamaterial cylinders with multiple dipole resonances

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2009-01-01

    It has been shown that the sub-wavelength resonances of the individual MTM cylinders also occur for electrically small configurations combining 2 or 4 cylinders. For the 2-and 4-cylinder configurations the overall size is 1/20 and 1/12.5 of the smallest wavelength, respectively. These MTM...... configuration thus offer the possibility for multi-resonant electrically small configurations....

  6. Modulating wavelength discrimination in goldfish with ethambutol and stimulus intensity

    NARCIS (Netherlands)

    Sjoerdsma, T.; Kamermans, M.; Spekreijse, H.

    1996-01-01

    Wavelength discrimination in goldfish was measured behaviourally. Both acute application of ethambutol injected into the eye and chronic application by feeding the animals daily 25 mg ethambutol for 1 month had the same effect on wavelength discrimination in the range of 560-640 nm. This means that:

  7. Influence of laser wavelength on the thermal responses of port wine stain lesions in light, moderate and heavy pigmented skin

    International Nuclear Information System (INIS)

    Li, D.; Chen, B.; Wu, W.J.; Ying, Z.X.

    2017-01-01

    Highlights: • Laser surgery for port wine stain (PWS) was studied by local non-equilibrium theory. • Wavelength selection in laser surgery under various skin pigmentation was explored. • High pigmented skin prefers to 585 nm rather then 595 nm. • Dual-wavelength laser (585/595 + 1064 nm) has better clinic effect than single one. • Deep buried blood vessels can be damaged by 595/1064 nm dual-wavelength laser. - Abstract: Pulsed dye laser (PDL) in visible band (e.g. 585 or 595 nm) together with cryogen spray cooling has become the golden standard for treatment of vascular malformation such as port wine stain (PWS). However, due to the limited energy penetration depth of the PDL, deeply buried blood vessels are likely to survive from the laser irradiation. Nd:YAG laser in near infrared (1064 nm) has great potential in the laser treatment of PWS due to its deeper penetration depth. In this study, the influence of laser wavelength in treating PWS lesions with various melanin concentrations in epidermis was theoretically investigated by a two-temperature model following the local thermal non-equilibrium theory of porous media. The results showed that deeply buried blood vessels can be coagulated by dual-wavelength laser combing 585 or 595 nm with 1064 nm laser. Furthermore, the therapeutic results by dual-wavelength laser were highly related to the melanin concentration in epidermis. In the light and moderate pigmented skin, the 595/1064 nm dual-wavelength laser showed better treatment effect in treating PWS with deeply-buried blood vessels than of 585/1064 nm dual-wavelength laser. For a high pigmented skin, the 585/1064 nm dual-wavelength laser showed better treatment effect than 595/1064 nm dual-wavelength laser.

  8. Optimal wavelength band clustering for multispectral iris recognition.

    Science.gov (United States)

    Gong, Yazhuo; Zhang, David; Shi, Pengfei; Yan, Jingqi

    2012-07-01

    This work explores the possibility of clustering spectral wavelengths based on the maximum dissimilarity of iris textures. The eventual goal is to determine how many bands of spectral wavelengths will be enough for iris multispectral fusion and to find these bands that will provide higher performance of iris multispectral recognition. A multispectral acquisition system was first designed for imaging the iris at narrow spectral bands in the range of 420 to 940 nm. Next, a set of 60 human iris images that correspond to the right and left eyes of 30 different subjects were acquired for an analysis. Finally, we determined that 3 clusters were enough to represent the 10 feature bands of spectral wavelengths using the agglomerative clustering based on two-dimensional principal component analysis. The experimental results suggest (1) the number, center, and composition of clusters of spectral wavelengths and (2) the higher performance of iris multispectral recognition based on a three wavelengths-bands fusion.

  9. Dual-Frequency Bistatic Radar Probing of Mars: Potential and Pitfalls for Depth Sounding at Centimeter Wavelengths

    Science.gov (United States)

    Simpson, R. A.; Tyler, G. L.; Paetzold, M.; Haeusler, B.; Asmar, S. W.

    2009-12-01

    Early spacecraft-to-Earth bistatic radar (BSR) probing of Mars' surface emphasized measurement of rms surface slopes on scales of centimeters to a few meters, information of particular interest to the design and deployment of landers and rovers. Shorter wavelengths yielded higher values, consistent with fractal models in which surface texture becomes rougher as the measuring instrument senses more detail. Although Mars Express (MEX) has found the smoothest extraterrestrial solid surface yet observed by radar (0.17 deg rms in the north polar region), its antenna pattern typically illuminates only part of the scattering surface, making rms slope determination difficult. With careful calibration, however, the ratio of echo power in its two orthogonal polarizations can be used to infer the dielectric constant of the surface material from the Fresnel reflection coefficients. Early results showed larger dielectric constant at 12.6 cm than 3.6 cm, consistent with materials which become more densely packed at depth; as the data collection continued, regional variations became apparent. More puzzling, are cases in which the derived dielectric constant is 30 percent larger at the shorter wavelength, suggesting a centimeter of crust (invisible at 12.6 cm wavelength) overlying less dense regolith below. Duricrust layers have been inferred in some of these areas from thermal measurements; and a layer of gravel, stripped of finer particles, could produce similar effects. Earth-to-spacecraft BSR could improve measurement sensitivity by factors of 100-1000; spacecraft-to-spacecraft experiments could improve surface coverage. All three configurations, including the conventional 'downlink' experiments now being conducted, can provide basic information on surface structure to depths of a few centimeters.

  10. High lung cancer surgical procedure volume is associated with shorter length of stay and lower risks of re-admission and death

    DEFF Research Database (Denmark)

    Møller, Henrik; Riaz, Sharma P; Holmberg, Lars

    2016-01-01

    It is debated whether treating cancer patients in high-volume surgical centres can lead to improvement in outcomes, such as shorter length of hospital stay, decreased frequency and severity of post-operative complications, decreased re-admission, and decreased mortality. The dataset for this anal......It is debated whether treating cancer patients in high-volume surgical centres can lead to improvement in outcomes, such as shorter length of hospital stay, decreased frequency and severity of post-operative complications, decreased re-admission, and decreased mortality. The dataset...... to their geographical population. Higher volume hospitals had shorter length of stay and the odds of re-admission were 15% lower in the highest hospital volume quintile compared with the lowest quintile. Mortality risks were 1% after 30 d and 3% after 90 d. Patients from hospitals in the highest volume quintile had...

  11. Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale

    Science.gov (United States)

    Cruikshank, D.P.; Meyer, A.W.; Brown, R.H.; Clark, R.N.; Jaumann, R.; Stephan, K.; Hibbitts, C.A.; Sandford, S.A.; Mastrapa, R.M.E.; Filacchione, G.; Ore, C.M.D.; Nicholson, P.D.; Buratti, B.J.; McCord, T.B.; Nelson, R.M.; Dalton, J.B.; Baines, K.H.; Matson, D.L.

    2010-01-01

    Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO2) at or near the nominal solid-phase laboratory wavelength of 4.2675 ??m (2343.3 cm-1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We report here on an analysis of the variation in wavelength and width of the CO2 absorption band in the spectra of Phoebe, Iapetus, Hyperion, and Dione. Comparisons are made to laboratory spectra of pure CO2, CO2 clathrates, ternary mixtures of CO2 with other volatiles, implanted and adsorbed CO2 in non-volatile materials, and ab initio theoretical calculations of CO2 * nH2O. At the wavelength resolution of VIMS, the CO2 on Phoebe is indistinguishable from pure CO2 ice (each molecule's nearby neighbors are also CO2) or type II clathrate of CO2 in H2O. In contrast, the CO2 band on Iapetus, Hyperion, and Dione is shifted to shorter wavelengths (typically ???4.255 ??m (???2350.2 cm-1)) and broadened. These wavelengths are characteristic of complexes of CO2 with different near-neighbor molecules that are encountered in other volatile mixtures such as with H2O and CH3OH, and non-volatile host materials like silicates, some clays, and zeolites. We suggest that Phoebe's CO2 is native to the body as part of the initial inventory of condensates and now exposed on the surface, while CO2 on the other three satellites results at least in part from particle or UV irradiation of native H2O plus a source of C, implantation or accretion from external sources, or redistribution of native CO2 from the interior. The analysis presented here depends on an accurate VIMS wavelength scale. In preparation for this work, the baseline wavelength calibration for the Cassini VIMS was found to be distorted around 4.3 ??m, apparently as a consequence of telluric CO2 gas absorption in the pre-launch calibration. The effect can be reproduced by convolving a sequence of model detector

  12. SARAS MEASUREMENT OF THE RADIO BACKGROUND AT LONG WAVELENGTHS

    International Nuclear Information System (INIS)

    Patra, Nipanjana; Subrahmanyan, Ravi; Sethi, Shiv; Shankar, N. Udaya; Raghunathan, A.

    2015-01-01

    SARAS is a correlation spectrometer connected to a frequency independent antenna that is purpose-designed for precision measurements of the radio background at long wavelengths. The design, calibration, and observing strategies admit solutions for the internal additive contributions to the radiometer response, and hence a separation of these contaminants from the antenna temperature. We present here a wideband measurement of the radio sky spectrum by SARAS that provides an accurate measurement of the absolute brightness and spectral index between 110 and 175 MHz. Accuracy in the measurement of absolute sky brightness is limited by systematic errors of magnitude 1.2%; errors in calibration and in the joint estimation of sky and system model parameters are relatively smaller. We use this wide-angle measurement of the sky brightness using the precision wide-band dipole antenna to provide an improved absolute calibration for the 150 MHz all-sky map of Landecker and Wielebinski: subtracting an offset of 21.4 K and scaling by a factor of 1.05 will reduce the overall offset error to 8 K (from 50 K) and scale error to 0.8% (from 5%). The SARAS measurement of the temperature spectral index is in the range −2.3 to −2.45 in the 110–175 MHz band and indicates that the region toward the Galactic bulge has a relatively flatter index

  13. GaAsSb/InGaAs type-II quantum wells for long-wavelength lasers on GaAs substrates

    International Nuclear Information System (INIS)

    Klem, J. F.; Blum, O.; Kurtz, S. R.; Fritz, I. J.; Choquette, K. D.

    2000-01-01

    We have investigated the properties of GaAsSb/InGaAs type-II bilayer quantum-well structures grown by molecular-beam epitaxy for use in long-wavelength lasers on GaAs substrates. Structures with layer strains and thicknesses designed to be thermodynamically stable against dislocation formation exhibit room-temperature photoluminescence at wavelengths as long as 1.43 μm. The photoluminescence emission wavelength is significantly affected by growth temperature and the sequence of layer growth (InGaAs/GaAsSb versus GaAsSb/InGaAs), suggesting that Sb and/or In segregation results in nonideal interfaces under certain growth conditions. At low-injection currents, double-heterostructure lasers with GaAsSb/InGaAs bilayer quantum-well active regions display electroluminescence at wavelengths comparable to those obtained in photoluminescence, but at higher currents the electroluminescence shifts to shorter wavelengths. Lasers have been obtained with threshold current densities of 120 A/cm2 at 1.17 μm, and 2.1 kA/cm2 at 1.21 μm. (c) 2000 American Vacuum Society

  14. Wavelength selection-based nonlinear calibration for transcutaneous blood glucose sensing using Raman spectroscopy

    Science.gov (United States)

    Dingari, Narahara Chari; Barman, Ishan; Kang, Jeon Woong; Kong, Chae-Ryon; Dasari, Ramachandra R.; Feld, Michael S.

    2011-01-01

    While Raman spectroscopy provides a powerful tool for noninvasive and real time diagnostics of biological samples, its translation to the clinical setting has been impeded by the lack of robustness of spectroscopic calibration models and the size and cumbersome nature of conventional laboratory Raman systems. Linear multivariate calibration models employing full spectrum analysis are often misled by spurious correlations, such as system drift and covariations among constituents. In addition, such calibration schemes are prone to overfitting, especially in the presence of external interferences that may create nonlinearities in the spectra-concentration relationship. To address both of these issues we incorporate residue error plot-based wavelength selection and nonlinear support vector regression (SVR). Wavelength selection is used to eliminate uninformative regions of the spectrum, while SVR is used to model the curved effects such as those created by tissue turbidity and temperature fluctuations. Using glucose detection in tissue phantoms as a representative example, we show that even a substantial reduction in the number of wavelengths analyzed using SVR lead to calibration models of equivalent prediction accuracy as linear full spectrum analysis. Further, with clinical datasets obtained from human subject studies, we also demonstrate the prospective applicability of the selected wavelength subsets without sacrificing prediction accuracy, which has extensive implications for calibration maintenance and transfer. Additionally, such wavelength selection could substantially reduce the collection time of serial Raman acquisition systems. Given the reduced footprint of serial Raman systems in relation to conventional dispersive Raman spectrometers, we anticipate that the incorporation of wavelength selection in such hardware designs will enhance the possibility of miniaturized clinical systems for disease diagnosis in the near future. PMID:21895336

  15. Demonstrated Wavelength Portability of Raman Reference Data for Explosives and Chemical Detection

    Directory of Open Access Journals (Sweden)

    Timothy J. Johnson

    2012-01-01

    Full Text Available As Raman spectroscopy continues to evolve, questions arise as to the portability of Raman data: dispersive versus Fourier transform, wavelength calibration, intensity calibration, and in particular the frequency of the excitation laser. While concerns about fluorescence arise in the visible or ultraviolet, most modern (portable systems use near-infrared excitation lasers, and many of these are relatively close in wavelength. We have investigated the possibility of porting reference data sets from one NIR wavelength system to another: We have constructed a reference library consisting of 145 spectra, including 20 explosives, as well as sundry other compounds and materials using a 1064 nm spectrometer. These data were used as a reference library to evaluate the same 145 compounds whose experimental spectra were recorded using a second 785 nm spectrometer. In 128 cases of 145 (or 88.3% including 20/20 for the explosives, the compounds were correctly identified with a mean “hit score” of 954 of 1000. Adding in criteria for when to declare a correct match versus when to declare uncertainty, the approach was able to correctly categorize 134 out of 145 spectra, giving a 92.4% accuracy. For the few that were incorrectly identified, either the matched spectra were spectroscopically similar to the target or the 785 nm signal was degraded due to fluorescence. The results indicate that imported data recorded at a different NIR wavelength can be successfully used as reference libraries, but key issues must be addressed: the reference data must be of equal or higher resolution than the resolution of the current sensor, the systems require rigorous wavelength calibration, and wavelength-dependent intensity response should be accounted for in the different systems.

  16. Single Mode Fiber Optic Transceiver Using Short Wavelength Active Devices In Long Wavelength Fiber

    Science.gov (United States)

    Gillham, Frederick J.; Campbell, Daniel R.; Corke, Michael; Stowe, David W.

    1990-01-01

    Presently, single mode optical fiber technology is being utilized in systems to supply telephone service to the subscriber. However, in an attempt to be competitive with copper based systems, there are many development programs underway to determine the most cost effective solution while still providing a service that will either satisfy or be upgradeable to satisfy the demands of the consumer for the next 10 to 20 years. One such approach is to combine low cost laser transmitters and silicon receivers, which have been developed for the "compact disc" industry, with fiber that operates in the single mode regime at 1300 nm. In this paper, an optical transceiver will be presented, consisting of a compact disc laser, a silicon detector and a single mode coupler at 1300 nm. A possible system layout is presented which operates at 780 nm bi-directionally for POTS and upgradeable to 1300 nm for video services. There are several important design criteria that have to be considered in the development of such a system which will be addressed. These include: 1. Optimization of coupled power from laser to fiber while maintaining stable launched conditions over a wide range of environmental conditions. 2. Consideration of the multimode operation of the 1300 nm single mode fiber while operating in the 780 nm wavelength region. 3. Development of a low cost pseudo-wavelength division multiplexer for 1300 nm single mode/780 nm multimode operation and a low cost dual mode 50/50, 780 nm splitter using 1300 nm fiber. Details will be given of the design criteria and solution in terms of optimized design. Results of the performance of several prototype devices will be given with indications of the merits of this approach and where further development effort should be applied.

  17. Free-space wavelength-multiplexed optical scanner.

    Science.gov (United States)

    Yaqoob, Z; Rizvi, A A; Riza, N A

    2001-12-10

    A wavelength-multiplexed optical scanning scheme is proposed for deflecting a free-space optical beam by selection of the wavelength of the light incident on a wavelength-dispersive optical element. With fast tunable lasers or optical filters, this scanner features microsecond domain scan setting speeds and large- diameter apertures of several centimeters or more for subdegree angular scans. Analysis performed indicates an optimum scan range for a given diffraction order and grating period. Limitations include beam-spreading effects based on the varying scanner aperture sizes and the instantaneous information bandwidth of the data-carrying laser beam.

  18. Rational choices for the wavelengths of a two color interferometer

    International Nuclear Information System (INIS)

    Jobes, F.C.

    1995-07-01

    If in a two color interferometer for plasma density measurements, the two wavelengths are chosen to have a ratio that is a rational number, and if the signals from each of the wavelengths are multiplied in frequency by the appropriate integer of the rational number and then heterodyned together, the resultant signal will have all effects of component motion nulled out. A phase measurement of this signal will have only plasma density information in it. With CO 2 lasers, it is possible to find suitable wavelength pairs which are close enough to rational numbers to produce an improvement of about 100 in density resolution, compared to standard two color interferometers

  19. Radiative flux calculations at UV and visible wavelengths

    International Nuclear Information System (INIS)

    Grossman, A.S.; Grant, K.E.; Wuebbles, D.J.

    1993-10-01

    A radiative transfer model to calculate the short wavelength fluxes at altitudes between 0 and 80 km has been developed at LLNL. The wavelength range extends from 175--735 nm. This spectral range covers the UV-B wavelength region, 250--350 nm, with sufficient resolution to allow comparison of UV-B measurements with theoretical predictions. Validation studies for the model have been made for both UV-B ground radiation calculations and tropospheric solar radiative forcing calculations for various ozone distributions. These studies indicate that the model produces results which agree well with respect to existing UV calculations from other published models

  20. Lethal action of ultraviolet and visible (blue violet) radiations at defined wavelengths on human lymphoblastoid cells; action spectra and interaction sites

    Energy Technology Data Exchange (ETDEWEB)

    Tyrrell, R.M.; Werfelli, P.; Moraes, E.C. (Institut Suisse de Recherches Experimentales sur le Cancer, Lausanne)

    1984-02-01

    The repair proficient human lymphoblastoid line (TK6) has been employed to construct an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254 to 434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the 334 to 405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources.

  1. Lethal action of ultraviolet and visible (blue violet) radiations at defined wavelengths on human lymphoblastoid cells; action spectra and interaction sites

    International Nuclear Information System (INIS)

    Tyrrell, R.M.; Werfelli, P.; Moraes, E.C.

    1984-01-01

    The repair proficient human lymphoblastoid line (TK6) has been employed to construct an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254 to 434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the 334 to 405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources. (author)

  2. Relativity

    CERN Document Server

    Einstein, Albert

    2013-01-01

    Time magazine's ""Man of the Century"", Albert Einstein is the founder of modern physics and his theory of relativity is the most important scientific idea of the modern era. In this short book, Einstein explains, using the minimum of mathematical terms, the basic ideas and principles of the theory that has shaped the world we live in today. Unsurpassed by any subsequent books on relativity, this remains the most popular and useful exposition of Einstein's immense contribution to human knowledge.With a new foreword by Derek Raine.

  3. 42 CFR 137.78 - May a Self-Governance Tribe negotiate a funding agreement for a term longer or shorter than one...

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false May a Self-Governance Tribe negotiate a funding agreement for a term longer or shorter than one year? 137.78 Section 137.78 Public Health PUBLIC HEALTH... SERVICES TRIBAL SELF-GOVERNANCE Funding General § 137.78 May a Self-Governance Tribe negotiate a funding...

  4. Cost-effectiveness of longer-term versus shorter-term provision of antibiotics in patients with persistent symptoms attributed to Lyme disease

    NARCIS (Netherlands)

    Berende, A.; Nieuwenhuis, L.; Hofstede, H.J.M. ter; Vos, F.J.; Vogelaar, M.L.; Tromp, M.A.; Middendorp, H. van; Donders, A.R.T.; Evers, A.W.M.; Kullberg, B.J.; Adang, E.M.M.

    2018-01-01

    BACKGROUND: The treatment of persistent symptoms attributed to Lyme disease remains controversial. Recently, the PLEASE study did not demonstrate any additional clinical benefit of longer-term versus shorter-term antibiotic treatment. However, the economic impact of the antibiotic strategies has not

  5. N-Terminal Domains in Two-Domain Proteins Are Biased to Be Shorter and Predicted to Fold Faster Than Their C-Terminal Counterparts

    Directory of Open Access Journals (Sweden)

    Etai Jacob

    2013-04-01

    Full Text Available Computational analysis of proteomes in all kingdoms of life reveals a strong tendency for N-terminal domains in two-domain proteins to have shorter sequences than their neighboring C-terminal domains. Given that folding rates are affected by chain length, we asked whether the tendency for N-terminal domains to be shorter than their neighboring C-terminal domains reflects selection for faster-folding N-terminal domains. Calculations of absolute contact order, another predictor of folding rate, provide additional evidence that N-terminal domains tend to fold faster than their neighboring C-terminal domains. A possible explanation for this bias, which is more pronounced in prokaryotes than in eukaryotes, is that faster folding of N-terminal domains reduces the risk for protein aggregation during folding by preventing formation of nonnative interdomain interactions. This explanation is supported by our finding that two-domain proteins with a shorter N-terminal domain are much more abundant than those with a shorter C-terminal domain.

  6. Ghostly Glow Reveals a Hidden Class of Long-Wavelength Radio Emitters

    Science.gov (United States)

    2008-10-01

    (Washington, DC. 08)- A team of scientists, including astronomers from the Naval Research Laboratory (NRL), have detected long wavelength radio emission from a colliding, massive galaxy cluster which, surprisingly, is not detected at the shorter wavelengths typically seen in these objects. The discovery implies that existing radio telescopes have missed a large population of these colliding objects. It also provides an important confirmation of the theoretical prediction that colliding galaxy clusters accelerate electrons and other particles to very high energies through the process of turbulent waves. The team revealed their findings in the October 16, 2008 edition of Nature. This new population of objects is most easily detected at long wavelengths. Professor Greg Taylor of the University of New Mexico and scientific director of the Long Wavelength Array (LWA) points out, "This result is just the tip of the iceberg. When an emerging suite of much more powerful low frequency telescopes, including the LWA in New Mexico, turn their views to the cosmos, the sky will 'light up' with hundreds or even thousands of colliding galaxy clusters." NRL has played a key role in promoting the development of this generation of new instruments and is currently involved with the development of the LWA. NRL radio astronomer and LWA Project Scientist Namir Kassim says "Our discovery of a previously hidden class of low frequency cluster-radio sources is particularly important since the study of galaxy clusters was a primary motivation for development of the LWA." The discovery of the emission in the galaxy cluster Abell 521 (or A521 for short) was made using the Giant Metrewave Radiotelescope (GMRT) in India, and its long wavelength nature was confirmed by the National Science Foundation's (NRAO) Very Large Array (VLA) radio telescope in New Mexico. The attached image shows the radio emission at a wavelength of 125cm in red superimposed on a blue image made from data taken by the

  7. Effect of wavelength shifters on water Cherenkov detectors

    Energy Technology Data Exchange (ETDEWEB)

    Badino, G; Galeotti, P; Periale, L; Saavedra, O; Turtelli, A [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale)

    1981-06-15

    We report the results of a test showing that concentrations of approx. equal to 2 mg/l of wavelength shifter in water give almost the maximum efficiency of detection without losing the directionality of Cherenkov light.

  8. Two-wavelength HeNe laser interferometer

    International Nuclear Information System (INIS)

    Granneman, E.H.A.

    1981-01-01

    This paper presents an interferometer set-up in which two wavelengths are used simultaneously. This enables one to determine separately the phase shifts caused by changes in plasma density and by mechanical vibrations of the interferometer structure

  9. Multi-wavelength Ocean Profiling and Atmospheric Lidar

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build and demonstrate the world's first multi-wavelength ocean-profiling high spectral resolution lidar (HSRL). The lidar will provide profiles of...

  10. Isoplanatic patch of the human eye for arbitrary wavelengths

    Science.gov (United States)

    Han, Guoqing; Cao, Zhaoliang; Mu, Quanquan; Wang, Yukun; Li, Dayu; Wang, Shaoxin; Xu, Zihao; Wu, Daosheng; Hu, Lifa; Xuan, Li

    2018-03-01

    The isoplanatic patch of the human eye is a key parameter for the adaptive optics system (AOS) designed for retinal imaging. The field of view (FOV) usually sets to the same size as the isoplanatic patch to obtain high resolution images. However, it has only been measured at a specific wavelength. Here we investigate the wavelength dependence of this important parameter. An optical setup is initially designed and established in a laboratory to measure the isoplanatic patch at various wavelengths (655 nm, 730 nm and 808 nm). We established the Navarro wide-angle eye model in Zemax software to further validate our results, which suggested high consistency between the two. The isoplanatic patch as a function of wavelength was obtained within the range of visible to near-infrared, which can be expressed as: θ=0.0028 λ - 0 . 74. This work is beneficial for the AOS design for retinal imaging.

  11. Portable Long-Wavelength Infrared Camera for Civilian Application

    Science.gov (United States)

    Gunapala, S. D.; Krabach, T. N.; Bandara, S. V.; Liu, J. K.

    1997-01-01

    In this paper, we discuss the performance of this portable long-wavelength infrared camera in quantum efficiency, NEAT, minimum resolvable temperature differnce (MRTD), uniformity, etc. and its application in science, medicine and defense.

  12. Infrared presensitization photography at deuterium fluoride laser wavelengths

    International Nuclear Information System (INIS)

    Geary, J.M.; Ross, K.; Suter, K.

    1989-01-01

    Near-field irradiance distributions of a deuterium flouride laser system are obtained using infrared presensitization photography. This represents the shortest wavelength region to employ this technique thus far

  13. Self-amplified spontaneous emission for short wavelength coherent radiation

    International Nuclear Information System (INIS)

    Kim, K.J.; Xie, M.

    1992-09-01

    We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented

  14. Valuing spectrum at mm wavelengths for cellular networks

    OpenAIRE

    Shaw, B. A.; Beltrán, H. F.; Sowerby, K. W.

    2017-01-01

    This paper investigates the economic value of spectrum at mm wavelengths. The analysis uses four techniques to value spectrum, namely a benchmarking comparison, a discounted cash flow analysis, a real options approach and a deprival method. The methods to calculate spectrum value presented in this paper can be used for any spectrum band and in any country. However, to determine the value of mm wavelengths for cellular networks, we have used data from New Zealand, specifically for the existing...

  15. Long wavelength scintillators for fiber-optic applications

    International Nuclear Information System (INIS)

    Lyons, P.B.; Franks, L.; Lutz, S.; Flournoy, J.; Fullman, E.

    1980-01-01

    The use of fiber optics in plasma diagnostics has spurred the development of long wavelength scintillators with fast temporal characteristics. In this paper we describe several new liquid scintillator systems with fluorescent emissions maxima up to 730 nm. Subnanosecond scintillator FWHM response times have been obtained by the operation of liquid scintillators at elevated temperatures. Data on fiber system sensitivity versus fiber length and scintillator emission wavelength will be presented

  16. Short-wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1985-01-01

    Recent observations with the ISEE 1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emission has a characteristic parabola shape or ''festoon'' shape. The low-frequency cutoff ranges from 100 to 400 Hz, while the high-frequency limit ranges from about 1 to 4 kHz. The bandwidth is found to minimize for antenna orientations parallel to the wave vectors. The wave vector does not appear to be related to the local magnetic field, the plasma flow velocity, or the spacecraft-sun directions. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler-shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest frame wave vectors and frequencies indicate that emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 40 and 600 m. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  17. The Support of Long Wavelength Loads on Venus

    Science.gov (United States)

    Benerdt, W. B.; Saunders, R. S.

    1985-01-01

    One of the great surprises of the Pioneer Venus mission was the high degree of correlation between topography and gravity found at all wavelengths. This implies a close relationship between topography and lateral subsurface density anomalies, such as those due to passive or dynamic compensation. Sleep-Phillips type compensation model with a variable crustal thickness and a variable upper mantle density was developed. The thin shell theory was used to investigate three end member cases: (1) loading by topographic construction, resulting in a downward deflection of the surface (no mantle support); (2) completely compensated support of a constructional load (no surface deflection); and (3) topography due entirely to upward deflection of the surface supported by a low density upper mantle (no surface load). In general, the models imply relatively thick crust and dense upper mantle for Ishtar Terra and Ovda Regio (western Aphrodite), thinned crust and buoyant upper mantle for Tethus Regio and regions near Sappho and Alpha Regio, and a nearly uniform crust with a buoyant upper mantle for Beta Regio and Atla Regio (eastern Aphrodite).

  18. Josephson frequency meter for millimeter and submillimeter wavelengths

    International Nuclear Information System (INIS)

    Anischenko, S.E.; Larkin, S.Y.; Chaikovsky, V.I.

    1994-01-01

    Frequency measurements of electromagnetic oscillations of millimeter and submillimeter wavebands with frequency growth due to a number of reasons become more and more difficult. First, these frequencies are considered to be cutoff for semiconductor converting devices and one has to use optical measurement methods instead of traditional ones with frequency transfer. Second, resonance measurement methods are characterized by using relatively narrow bands and optical ones are limited in frequency and time resolution due to the limited range and velocity of movement of their mechanical elements as well as the efficiency of these optical techniques decreases with the increase of wavelength due to diffraction losses. That requires the apriori information on the radiation frequency band of the source involved. Method of measuring frequency of harmonic microwave signals in millimeter and submillimeter wavebands based on the ac Josephson effect in superconducting contacts is devoid of all the above drawbacks. This approach offers a number of major advantages over the more traditional measurement methods, that is the one based on frequency conversion, resonance and interferrometric techniques. It can be characterized by high potential accuracy, wide range of frequencies measured, prompt measurement and the opportunity to obtain panoramic display of the results as well as full automation of the measuring process

  19. Josephson frequency meter for millimeter and submillimeter wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Anischenko, S.E.; Larkin, S.Y.; Chaikovsky, V.I. [State Research Center, Kiev (Ukraine)] [and others

    1994-12-31

    Frequency measurements of electromagnetic oscillations of millimeter and submillimeter wavebands with frequency growth due to a number of reasons become more and more difficult. First, these frequencies are considered to be cutoff for semiconductor converting devices and one has to use optical measurement methods instead of traditional ones with frequency transfer. Second, resonance measurement methods are characterized by using relatively narrow bands and optical ones are limited in frequency and time resolution due to the limited range and velocity of movement of their mechanical elements as well as the efficiency of these optical techniques decreases with the increase of wavelength due to diffraction losses. That requires the apriori information on the radiation frequency band of the source involved. Method of measuring frequency of harmonic microwave signals in millimeter and submillimeter wavebands based on the ac Josephson effect in superconducting contacts is devoid of all the above drawbacks. This approach offers a number of major advantages over the more traditional measurement methods, that is the one based on frequency conversion, resonance and interferrometric techniques. It can be characterized by high potential accuracy, wide range of frequencies measured, prompt measurement and the opportunity to obtain panoramic display of the results as well as full automation of the measuring process.

  20. Dielectric properties of alumina/zirconia composites at millimeter wavelengths

    International Nuclear Information System (INIS)

    Molla, J.; Heidinger, R.; Ibarra, A.; Link, G.

    1994-01-01

    Alumina-zirconia composites with ZrO 2 contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO 2 is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO 2 , t-ZrO 2 ). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al 2 O 3 , 14-21 for m-ZrO 2 and 40-45 for t-ZrO 2 . The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO 2 ; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO 2 , which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO 2 strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO 2 is avoided

  1. Line identification studies using traditional techniques and wavelength coincidence statistics

    International Nuclear Information System (INIS)

    Cowley, C.R.; Adelman, S.J.

    1990-01-01

    Traditional line identification techniques result in the assignment of individual lines to an atomic or ionic species. These methods may be supplemented by wavelength coincidence statistics (WCS). The strength and weakness of these methods are discussed using spectra of a number of normal and peculiar B and A stars that have been studied independently by both methods. The present results support the overall findings of some earlier studies. WCS would be most useful in a first survey, before traditional methods have been applied. WCS can quickly make a global search for all species and in this way may enable identifications of an unexpected spectrum that could easily be omitted entirely from a traditional study. This is illustrated by O I. WCS is a subject to well known weakness of any statistical technique, for example, a predictable number of spurious results are to be expected. The danger of small number statistics are illustrated. WCS is at its best relative to traditional methods in finding a line-rich atomic species that is only weakly present in a complicated stellar spectrum

  2. Using a fast dual-wavelength imaging ellipsometric system to measure the flow thickness profile of an oil thin film

    Science.gov (United States)

    Kuo, Chih-Wei; Han, Chien-Yuan; Jhou, Jhe-Yi; Peng, Zeng-Yi

    2017-11-01

    Dual-wavelength light sources with stroboscopic illumination technique were applied in a process of photoelastic modulated ellipsometry to retrieve two-dimensional ellipsometric parameters of thin films on a silicon substrate. Two laser diodes were alternately switched on and modulated by a programmable pulse generator to generate four short pulses at specific temporal phase angles in a modulation cycle, and short pulses were used to freeze the intensity variation of the PEM modulated signal that allows ellipsometric images to be captured by a charge-coupled device. Although the phase retardation of a photoelastic modulator is related to the light wavelength, we employed an equivalent phase retardation technique to avoid any setting from the photoelastic modulator. As a result, the ellipsometric parameters of different wavelengths may be rapidly obtained using this dual-wavelength ellipsometric system every 4 s. Both static and dynamic experiments are demonstrated in this work.

  3. Long-wavelength fluctuations and the glass transition in two dimensions and three dimensions.

    Science.gov (United States)

    Vivek, Skanda; Kelleher, Colm P; Chaikin, Paul M; Weeks, Eric R

    2017-02-21

    Phase transitions significantly differ between 2D and 3D systems, but the influence of dimensionality on the glass transition is unresolved. We use microscopy to study colloidal systems as they approach their glass transitions at high concentrations and find differences between two dimensions and three dimensions. We find that, in two dimensions, particles can undergo large displacements without changing their position relative to their neighbors, in contrast with three dimensions. This is related to Mermin-Wagner long-wavelength fluctuations that influence phase transitions in two dimensions. However, when measuring particle motion only relative to their neighbors, two dimensions and three dimensions have similar behavior as the glass transition is approached, showing that the long-wavelength fluctuations do not cause a fundamental distinction between 2D and 3D glass transitions.

  4. Optical cross-connect circuit using hitless wavelength selective switch.

    Science.gov (United States)

    Goebuchi, Yuta; Hisada, Masahiko; Kato, Tomoyuki; Kokubun, Yasuo

    2008-01-21

    We have proposed and demonstrated the basic elements of a full matrix optical switching circuit (cross-connect circuit) using a hitless wavelength selective switch (WSS). The cross-connect circuits are made of a multi-wavelength channel selective switch consisting of cascaded hitless WSSs, and a multi-port switch. These switching elements are realized through the individual Thermo-Optic (TO) tuning of a series-coupled microring resonator, and can switch arbitrary wavelength channels without blocking other wavelength channels during tuning. We demonstrate a four wavelength selective switch using a parallel topology of double series coupled microring resonators and a three wavelength selective switch using a parallel topology of quadruple series coupled microring resonators. Since the spectrum shape of quadruple series coupled microring is much more box-like than the double series, a high extinction ratio of 39.0-46.6 dB and low switching cross talk of 19.3-24.5 dB were achieved.

  5. Impact of beacon wavelength on phase-compensation performance

    Science.gov (United States)

    Enterline, Allison A.; Spencer, Mark F.; Burrell, Derek J.; Brennan, Terry J.

    2017-09-01

    This study evaluates the effects of beacon-wavelength mismatch on phase-compensation performance. In general, beacon-wavelength mismatch occurs at the system level because the beacon-illuminator laser (BIL) and high-energy laser (HEL) are often at different wavelengths. Such is the case, for example, when using an aperture sharing element to isolate the beam-control sensor suite from the blinding nature of the HEL. With that said, this study uses the WavePlex Toolbox in MATLAB® to model ideal spherical wave propagation through various atmospheric-turbulence conditions. To quantify phase-compensation performance, we also model a nominal adaptive-optics (AO) system. We achieve correction from a Shack-Hartmann wavefront sensor and continuous-face-sheet deformable mirror using a least-squares phase reconstruction algorithm in the Fried geometry and a leaky integrator control law. To this end, we plot the power in the bucket metric as a function of BIL-HEL wavelength difference. Our initial results show that positive BIL-HEL wavelength differences achieve better phase compensation performance compared to negative BIL-HEL wavelength differences (i.e., red BILs outperform blue BILs). This outcome is consistent with past results.

  6. Electronic band-gap modified passive silicon optical modulator at telecommunications wavelengths.

    Science.gov (United States)

    Zhang, Rui; Yu, Haohai; Zhang, Huaijin; Liu, Xiangdong; Lu, Qingming; Wang, Jiyang

    2015-11-13

    The silicon optical modulator is considered to be the workhorse of a revolution in communications. In recent years, the capabilities of externally driven active silicon optical modulators have dramatically improved. Self-driven passive modulators, especially passive silicon modulators, possess advantages in compactness, integration, low-cost, etc. Constrained by a large indirect band-gap and sensitivity-related loss, the passive silicon optical modulator is scarce and has been not advancing, especially at telecommunications wavelengths. Here, a passive silicon optical modulator is fabricated by introducing an impurity band in the electronic band-gap, and its nonlinear optics and applications in the telecommunications-wavelength lasers are investigated. The saturable absorption properties at the wavelength of 1.55 μm was measured and indicates that the sample is quite sensitive to light intensity and has negligible absorption loss. With a passive silicon modulator, pulsed lasers were constructed at wavelengths at 1.34 and 1.42 μm. It is concluded that the sensitive self-driven passive silicon optical modulator is a viable candidate for photonics applications out to 2.5 μm.

  7. High-efficiency and low-loss gallium nitride dielectric metasurfaces for nanophotonics at visible wavelengths

    Science.gov (United States)

    Emani, Naresh Kumar; Khaidarov, Egor; Paniagua-Domínguez, Ramón; Fu, Yuan Hsing; Valuckas, Vytautas; Lu, Shunpeng; Zhang, Xueliang; Tan, Swee Tiam; Demir, Hilmi Volkan; Kuznetsov, Arseniy I.

    2017-11-01

    The dielectric nanophotonics research community is currently exploring transparent material platforms (e.g., TiO2, Si3N4, and GaP) to realize compact high efficiency optical devices at visible wavelengths. Efficient visible-light operation is key to integrating atomic quantum systems for future quantum computing. Gallium nitride (GaN), a III-V semiconductor which is highly transparent at visible wavelengths, is a promising material choice for active, nonlinear, and quantum nanophotonic applications. Here, we present the design and experimental realization of high efficiency beam deflecting and polarization beam splitting metasurfaces consisting of GaN nanostructures etched on the GaN epitaxial substrate itself. We demonstrate a polarization insensitive beam deflecting metasurface with 64% and 90% absolute and relative efficiencies. Further, a polarization beam splitter with an extinction ratio of 8.6/1 (6.2/1) and a transmission of 73% (67%) for p-polarization (s-polarization) is implemented to demonstrate the broad functionality that can be realized on this platform. The metasurfaces in our work exhibit a broadband response in the blue wavelength range of 430-470 nm. This nanophotonic platform of GaN shows the way to off- and on-chip nonlinear and quantum photonic devices working efficiently at blue emission wavelengths common to many atomic quantum emitters such as Ca+ and Sr+ ions.

  8. Selective binding of carotenoids with a shorter conjugated chain to the LH2 antenna complex and those with a longer conjugated chain to the reaction center from Rubrivivax gelatinosus.

    Science.gov (United States)

    Kakitani, Yoshinori; Fujii, Ritsuko; Hayakawa, Yoshihiro; Kurahashi, Masahiro; Koyama, Yasushi; Harada, Jiro; Shimada, Keizo

    2007-06-19

    Rubrivivax gelatinosus having both the spheroidene and spirilloxanthin biosynthetic pathways produces carotenoids (Cars) with a variety of conjugated chains, which consist of different numbers of conjugated double bonds (n), including the C=C (m) and C=O (o) bonds. When grown under anaerobic conditions, the wild type produces Cars for which n = m = 9-13, whereas under semiaerobic conditions, it additionally produces Cars for which n = m + o = 10 + 1, 13 + 1, and 13 + 2. On the other hand, a mutant, in which the latter pathway is genetically blocked, produces only Cars for which n = 9 and 10 under anaerobic conditions and n = 9, 10, and 10 + 1 under semianaerobic conditions. Those Cars that were extracted from the LH2 complex (LH2) and the reaction center (RC), isolated from the wild-type and the mutant Rvi. gelatinosus, were analyzed by HPLC, and their structures were determined by mass spectrometry and 1H NMR spectroscopy. The selective binding of Cars to those pigment-protein complexes has been characterized as follows. (1) Cars with a shorter conjugated chain are selectively bound to LH2 whereas Cars with a longer conjugated chain to the RC. (2) Shorter chain Cars with a hydroxyl group are bound to LH2 almost exclusively. This rule holds either in the absence or in the presence of the keto group. The natural selection of shorter chain Cars by LH2 and longer chain Cars by the RC is discussed, on the basis of the results now available, in relation to the light-harvesting and photoprotective functions of Cars.

  9. Wavelength selection in the crown splash

    Science.gov (United States)

    Zhang, Li V.; Brunet, Philippe; Eggers, Jens; Deegan, Robert D.

    2010-12-01

    The impact of a drop onto a liquid layer produces a splash that results from the ejection and dissolution of one or more liquid sheets, which expand radially from the point of impact. In the crown splash parameter regime, secondary droplets appear at fairly regularly spaced intervals along the rim of the sheet. By performing many experiments for the same parameter values, we measure the spectrum of small-amplitude perturbations growing on the rim. We show that for a range of parameters in the crown splash regime, the generation of secondary droplets results from a Rayleigh-Plateau instability of the rim, whose shape is almost cylindrical. In our theoretical calculation, we include the time dependence of the base state. The remaining irregularity of the pattern is explained by the finite width of the Rayleigh-Plateau dispersion relation. Alternative mechanisms, such as the Rayleigh-Taylor instability, can be excluded for the experimental parameters of our study.

  10. The wavelength dependence of polarization in NGC 2023

    International Nuclear Information System (INIS)

    Rolph, C. D.; Scarrott, S. M.

    1989-01-01

    NGC 2023 is a bright reflection nebula illuminated by the central star HD37903. At 2 microns the nebula is seen solely by reflected light from the central star but in the NIR there is excess radiation that is supposed to arise from thermal emission from a population of small grains (Sellgren, 1984). The unexpectedly high surface brightness at R and I wavelengths has led to the suggestion that even at these wavelengths there is a significant contribution from this thermal emission process (Witt, Schild, and Kraiman, 1984). If the nebula is seen by reflected starlight then this radiation will be linearly polarized. The level of polarization depends on the scattering geometry, grain size distribution, etc., and is typically 20 to 40 percent for nebulae such as NGC 1999 which is morphologically similar to NGC 2023. If, in any waveband, there is a contribution of radiation from emission processes this radiation will be unpolarized and will serve to dilute the scattered radiation to give a lower level of observed polarization. A study of the wavelength dependence of polarization in nebulae in which there may be thermal emission from grains will indicate the contribution from this process to the total luminosity. Polarization maps were produced in BVRI wavebands for the NGC 2023 nebulosity which confirm that at all wavelengths it is a reflection nebula illuminated by a central star. The wavelength dependence of polarization at representative points in the nebula and in a scatter plot of polarization in V and I wavebands at all points at which measurements are given. Results indicate that throughout the nebula there is a general trend for the level of polarization to increase with wavelength and that maximum levels of polarization occur at the longest wavelengths. No evidence is seen in the data for any significant contribution from the thermal emission from grains in the BVRI luminosity of NGC 2023

  11. Laser wavelength dependent properties of YBa2Cu3O7-δ thin films deposited by laser ablation

    International Nuclear Information System (INIS)

    Koren, G.; Gupta, A.; Baseman, R.J.; Lutwyche, M.I.; Laibowitz, R.B.

    1989-01-01

    YBa 2 Cu 3 O 7-δ thin films were deposited onto (100) SrTiO 3 substrates using 1064, 532, 355, 248, and 193 nm laser ablation. Transport measurements show lower normal-state resistivities and higher critical currents in films deposited by the shorter wavelength lasers. The surface morphology of the films was rough with large particulates when the 1064 nm laser was used whereas much smoother surfaces with fewer and smaller particulates were obtained with the UV lasers. It is suggested that the better film quality obtained when the UV lasers are used is due to a small absorption depth of the UV photons in the ceramic target and to higher absorption by the ablated fragments. This leads to smaller ablated species and further fragmentation in the hotter plume and, therefore, to smoother and denser films

  12. Toward Shorter Hospitalization After Endoscopic Transsphenoidal Pituitary Surgery: Day-by-Day Analysis of Early Postoperative Complications and Interventions.

    Science.gov (United States)

    Shimanskaya, Viktoria E; Wagenmakers, Margreet A E M; Bartels, Ronald H M A; Boogaarts, Hieronymus D; Grotenhuis, J André; Hermus, Ad R M M; van de Ven, Annenienke C; van Lindert, Erik J

    2018-03-01

    It is unclear which patients have the greatest risk of developing complications in the first days after endoscopic transsphenoidal pituitary surgery (ETS) and how long patients should stay hospitalized after surgery. The objective of this study is to identify which patients are at risk for early postoperative medical and surgical reinterventions to optimize the length of hospitalization. The medical records of 146 patients who underwent ETS for a pituitary adenoma between January 2013 and July 2016 were reviewed retrospectively. Data were collected on baseline patient-related characteristics, characteristics of the pituitary adenoma, perioperative complications and interventions, and postoperative outcomes. Patients who underwent additional interventions on days 2, 3, and 4 after ETS were identified as cases, and patients who did not have any interventions after day 1 postoperatively were identified as controls. Diabetes mellitus (odds ratio [OR], 4.279; 95% confidence interval [CI], 1.149-15.933; P = 0.03), incomplete adenoma resection (OR, 2.840; 95% CI, 1.228-6.568; P = 0.02) and increased morning sodium concentration on day 2 after surgery (OR, 5.211; 95% CI, 2.158-12.579; P surgery have an increased chance on reinterventions. In addition, patients without any interventions on day 1 and 2 are at low risk for later reinterventions. These patients could be suitable candidates for early hospital discharge. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Shorter maintenance therapy in childhood Acute Lymphoblastic Leukemia. The experience of the prospective, randomized Brazilian GBTLI ALL-93 protocol.

    Directory of Open Access Journals (Sweden)

    Silvia Regina Brandalise

    2016-10-01

    Full Text Available Maintenance therapy is an important phase of the childhood ALL treatment, requiring 2-year long therapy adherence of the patients and families. Weekly methotrexate (MTX with daily 6-mercaptopurine (6MP constitutes the backbone of maintenance therapy. Reduction in the maintenance therapy could overweight problems related with poverty of children with ALL living in Limited-Income countries (LIC. Objective: To compare, prospectively, the EFS rates of children with ALL treated according to two maintenance regimens: 18 vs 24 months duration. Materials and Methods: From October 1993 to September 1999, 867 consecutive untreated ALL patients 10 years and high WBC at diagnosis. Overall death in remission rate was 6.85% (56 patients. Deaths during maintenance were 13 in group 1 and 12 in group 2, all due to infection. Over 15 years of follow-up, two patients both from Group 2 presented a second malignancy (Hodgkin’s disease and thyroid carcinoma after 8.3 and 11 years off therapy, respectively. Conclusion: Six-month reduction of maintenance therapy in ALL children treated according to the GBTLI ALL-93 protocol, provided the same overall outcome as 2-year duration regimen.

  14. All-optical 40 Gbit/s compact integrated interferometric wavelength converter

    DEFF Research Database (Denmark)

    Jørgensen, Carsten; Danielsen, Søren Lykke; Hansen, Peter Bukhave

    1997-01-01

    An interferometric Michelson wavelength converter is presented that combines a speed-optimized semiconductor optical amplifier technology with the benefits of the integrated interferometer showing 40-Gbit/s wavelength conversion. The optimized wavelength converter demonstrates noninverted converted...

  15. Laboratory study of nitrate photolysis in Antarctic snow. II. Isotopic effects and wavelength dependence

    Energy Technology Data Exchange (ETDEWEB)

    Berhanu, Tesfaye A.; Erbland, Joseph; Savarino, Joël [Laboratoire de Glaciologie et Géophysique de l’Environnement, CNRS, F-38041 Grenoble (France); Univ. Grenoble Alpes, LGGE, F-38041 Grenoble (France); Meusinger, Carl; Johnson, Matthew S. [Copenhagen Center for Atmospheric Research (CCAR), Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Jost, Rémy [Laboratoire de Interdisciplinaire de Physique (LIPHY) Univ. de Grenoble, Grenoble (France); Bhattacharya, S. K. [Research Center for Environmental Changes, Academia Sinica, Nangang, Taipei 115, Taiwan (China)

    2014-06-28

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [“Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry,” J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate ({sup 15}N, {sup 17}O, and {sup 18}O) provide additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters. The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ{sup 15}N, δ{sup 18}O, and Δ{sup 17}O). From these measurements an average photolytic isotopic fractionation of {sup 15}ε = (−15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation of the intense absorption band of nitrate around 200 nm in addition to the weaker band centered at 305 nm followed by photodissociation. An experiment with a filter blocking wavelengths shorter than 320 nm, approximating the actinic flux spectrum at Dome C, yielded a photolytic isotopic fractionation of {sup 15}ε = (−47.9 ± 6.8)‰, in good agreement with fractionations determined by previous studies for the East Antarctic Plateau which range from −40 to −74.3‰. We describe a new semi-empirical zero point energy shift model used to derive the absorption cross sections of {sup 14}NO{sub 3}{sup −} and {sup 15}NO{sub 3}{sup −} in snow at a chosen temperature. The nitrogen isotopic fractionations obtained by applying

  16. AlGaN-based laser diodes for the short-wavelength ultraviolet region

    International Nuclear Information System (INIS)

    Yoshida, Harumasa; Kuwabara, Masakazu; Yamashita, Yoji; Takagi, Yasufumi; Uchiyama, Kazuya; Kan, Hirofumi

    2009-01-01

    We have demonstrated the room-temperature operation of GaN/AlGaN and indium-free AlGaN multiple-quantum-well (MQW) laser diodes under the pulsed-current mode. We have successfully grown low-dislocation-density AlGaN films with AlN mole fractions of 20 and 30% on sapphire substrates using the hetero-facet-controlled epitaxial lateral overgrowth (hetero-FACELO) method. GaN/AlGaN and AlGaN MQW laser diodes have been fabricated on the low-dislocation-density Al 0.2 Ga 0.8 N and Al 0.3 Ga 0.7 N films, respectively. The GaN/AlGaN MQW laser diodes lased at a peak wavelength ranging between 359.6 and 354.4 nm. A threshold current density of 8 kA cm -2 , an output power as high as 80 mW and a differential external quantum efficiency (DEQE) of 17.4% have been achieved. The AlGaN MQW laser diodes lased at a peak wavelength down to 336.0 nm far beyond the GaN band gap. For the GaN/AlGaN MQW laser diodes, the modal gain coefficient and the optical internal loss are estimated to be 4.7±0.6 cm kA -1 and 10.6±2.7 cm -1 , respectively. We have observed that the characteristic temperature T 0 ranges from 132 to 89 K and DEQE shows an almost stable tendency with increase of temperature. A temperature coefficient of 0.049 nm K -1 is also found for the GaN/AlGaN MQW laser diode. The results for the AlGaN-based laser diodes grown on high-quality AlGaN films presented here will be essential for the future development of laser diodes emitting much shorter wavelengths.

  17. Comparison of different Aethalometer correction schemes and a reference multi-wavelength absorption technique for ambient aerosol data

    Science.gov (United States)

    Saturno, Jorge; Pöhlker, Christopher; Massabò, Dario; Brito, Joel; Carbone, Samara; Cheng, Yafang; Chi, Xuguang; Ditas, Florian; Hrabě de Angelis, Isabella; Morán-Zuloaga, Daniel; Pöhlker, Mira L.; Rizzo, Luciana V.; Walter, David; Wang, Qiaoqiao; Artaxo, Paulo; Prati, Paolo; Andreae, Meinrat O.

    2017-08-01

    Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP) data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA), which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June-September 2014). The mean absorption coefficient (at 637 nm) during this period was 1.8 ± 2.1 Mm-1, with a maximum of 15.9 Mm-1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption Ångström exponent (åABS) retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct åABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the åABS retrieved from offline MWAA measurements.

  18. Influence of opalescence and fluorescence properties on the light transmittance of resin composite as a function of wavelength.

    Science.gov (United States)

    Lee, Yong-Keun; Powers, John M

    2006-10-01

    To determine the influence of opalescence and fluorescence properties on the light transmittance of resin composites as a function of wavelength (410-750 nm). Spectral distribution of seven resin composites of A2 shade was measured according to the CIELAB color scale relative to the standard illuminant D65 in the reflectance and transmittance modes. Opalescence spectrum (OPS) was calculated as the subtraction spectrum (i.e., the spectrum measured in the transmittance mode subtracted at each wavelength from the spectrum measured in the reflectance mode). UV component of the illuminant was included and excluded to calculate the fluorescence spectrum (FLR and FLT in the reflectance and transmittance mode, respectively). Contrast ratio (CR) was calculated as the ratio of reflectance over a black background and over a white background. The total transmittance spectral distribution (TSD) value was used as the parameter to indicate masking ability of the resin composites over background color. Multiple regression analyses were performed among TSD and other optical parameters at the significance level of 0.05. In all the resin composites and wavelength range, correlation between CR and TSD was very high (r = -0.99). Correlations between each parameters varied by the wavelength range of fluorescence (410-500 nm) and no-fluorescence (510-750 nm). Correlation between OPS and TSD varied by the wavelength range (r = -0.86 to -0.94, Popalescence and fluorescence of resin composite varied by the wavelength.

  19. Accelerator physics and radiometric properties of superconducting wavelength shifters; Beschleunigerphysik und radiometrische Eigenschaften supraleitender Wellenlaengenschieber

    Energy Technology Data Exchange (ETDEWEB)

    Scheer, Michael

    2008-11-17

    Subject of this thesis is the operation of wave-length shifters at electron storage rings and their use in radiometry. The basic aspects of the radiometry, the technical requirements, the influence of wave-length shifters on the storage ring, and results of first measurements are presented for a device installed at BESSY. Most of the calculations are carried out by the program WAVE, which has been developed within this thesis. WAVE allows to calculate the synchrotron radiation spectra of wavelength shifters within an relative uncertainty of 1/100000. The properties of wave-length shifters in terms of accelerator physics as well as a generating function for symplectic tracking calculations can also be calculated by WAVE. The later was implemented in the tracking code BETA to investigate the influence of insertion devices on the dynamic aperture and emittance of the storage ring. These studies led to the concept of alternating low- and high-beta-sections at BESSY-II, which allow to operate superconducting insertion devices without a significant distortion of the magnetic optics. To investigate the experimental aspects of the radiometry at wave-length shifters, a program based on the Monte-Carlo-code GEANT4 has been developed. It allows to simulate the radiometrical measurements and the absorption properties of detectors. With the developed codes first radiometrical measurements by the PTB have been analysed. A comparison of measurements and calculations show a reasonable agreement with deviations of about five percent in the spectral range of 40-60 keV behind a 1-mm-Cu filter. A better agreement was found between 20 keV and 80 keV without Cu filter. In this case the measured data agreed within a systematic uncertainty of two percent with the results of the calculations. (orig.)

  20. Long wavelength infrared radiation thermometry for non-contact temperature measurements in gas turbines

    Science.gov (United States)

    Manara, J.; Zipf, M.; Stark, T.; Arduini, M.; Ebert, H.-P.; Tutschke, A.; Hallam, A.; Hanspal, J.; Langley, M.; Hodge, D.; Hartmann, J.

    2017-01-01

    The objective of the EU project "Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (acronym STARGATE)" is the development of a suite of advanced sensors, instrumentation and related systems in order to contribute to the developing of the next generation of green and efficient gas turbine engines. One work package of the project deals with the design and development of a long wavelength infrared (LWIR) radiation thermometer for the non-contact measurement of the surface temperature of thermal barrier coatings (TBCs) during the operation of gas turbine engines. For opaque surfaces (e.g. metals or superalloys) radiation thermometers which are sensitive in the near or short wavelength infrared are used as state-of-the-art method for non-contact temperature measurements. But this is not suitable for oxide ceramic based TBCs (e.g. partially yttria stabilized zirconia) as oxide ceramics are semi-transparent in the near and short wavelength infrared spectral region. Fortunately the applied ceramic materials are non-transparent in the long wavelength infrared and additionally exhibit a high emittance in this wavelength region. Therefore, a LWIR pyrometer can be used for non-contact temperature measurements of the surfaces of TBCs as such pyrometers overcome the described limitation of existing techniques. For performing non-contact temperature measurements in gas turbines one has to know the infrared-optical properties of the applied TBCs as well as of the hot combustion gas in order to properly analyse the measurement data. For reaching a low uncertainty on the one hand the emittance of the TBC should be high (>0.9) in order to reduce reflections from the hot surrounding and on the other hand the absorbance of the hot combustion gas should be low (<0.1) in order to decrease the influence of the gas on the measured signal. This paper presents the results of the work performed by the authors with focus on the implementation of the LWIR pyrometer and the

  1. Selection of Quantum Dot Wavelengths for Biomedical Assays and Imaging

    Directory of Open Access Journals (Sweden)

    Yong Taik Lim

    2003-01-01

    Full Text Available Fluorescent semiconductor nanocrystals (quantum dots [QDs] are hypothesized to be excellent contrast agents for biomedical assays and imaging. A unique property of QDs is that their absorbance increases with increasing separation between excitation and emission wavelengths. Much of the enthusiasm for using QDs in vivo stems from this property, since photon yield should be proportional to the integral of the broadband absorption. In this study, we demonstrate that tissue scatter and absorbance can sometimes offset increasing QD absorption at bluer wavelengths, and counteract this potential advantage. By using a previously validated mathematical model, we explored the effects of tissue absorbance, tissue scatter, wavelength dependence of the scatter, water-to- hemoglobin ratio, and tissue thickness on QD performance. We conclude that when embedded in biological fluids and tissues, QD excitation wavelengths will often be quite constrained, and that excitation and emission wavelengths should be selected carefully based on the particular application. Based on our results, we produced near-infrared QDs optimized for imaging surface vasculature with white light excitation and a silicon CCD camera, and used them to image the coronary vasculature in vivo. Taken together, our data should prove useful in designing fluorescent QD contrast agents optimized for specific biomedical applications.

  2. A Multi-Wavelength IR Laser for Space Applications

    Science.gov (United States)

    Li, Steven X.; Yu, Anthony W.; Sun, Xiaoli; Fahey, Molly E.; Numata, Kenji; Krainak, Michael A.

    2017-01-01

    We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to mid-infrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 microns, 2.7 microns and 3.4 microns. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated.

  3. Choice of the laser wavelength for a herpetic keratitis treatment

    Science.gov (United States)

    Razhev, Alexander M.; Bagayev, Sergei N.; Chernikh, Valery V.; Kargapoltsev, Evgeny S.; Trunov, Alexander; Zhupikov, Andrey A.

    2002-06-01

    For the first time the effect of the UV laser radiation to human eye cornea with herpetic keratitis was experimentally investigated. In experiments the UV radiation of ArF (193 nm), KrCl (223 nm), KrF (248 nm) excimer lasers were used. Optimal laser radiation parameters for the treatment of the herpetic keratitis were determined. The immuno-biochemical investigations were carried out and the results of clinical trials are presented. The maximum ablation rate was obtained for the 248 nm radiation wavelength. The process of healing was successful but in some cases the haze on the surface of the cornea was observed. When used the 193 nm radiation wavelength the corneal surface was clear without any hazes but the epithelization process was slower than for 248 nm wavelength and in some cases the relapse was occurred. The best results for herpetic keratitis treatment have been achieved by utilizing the 223 nm radiation wavelength of the KrCl excimer laser. The use of the 223 nm radiation wavelength allows treating the herpetic keratitis with low traumatic process of ablation and provides high quality of corneal surface.

  4. Wavelength calibration of imaging spectrometer using atmospheric absorption features

    Science.gov (United States)

    Zhou, Jiankang; Chen, Yuheng; Chen, Xinhua; Ji, Yiqun; Shen, Weimin

    2012-11-01

    Imaging spectrometer is a promising remote sensing instrument widely used in many filed, such as hazard forecasting, environmental monitoring and so on. The reliability of the spectral data is the determination to the scientific communities. The wavelength position at the focal plane of the imaging spectrometer will change as the pressure and temperature vary, or the mechanical vibration. It is difficult for the onboard calibration instrument itself to keep the spectrum reference accuracy and it also occupies weight and the volume of the remote sensing platform. Because the spectral images suffer from the atmospheric effects, the carbon oxide, water vapor, oxygen and solar Fraunhofer line, the onboard wavelength calibration can be processed by the spectral images themselves. In this paper, wavelength calibration is based on the modeled and measured atmospheric absorption spectra. The modeled spectra constructed by the atmospheric radiative transfer code. The spectral angle is used to determine the best spectral similarity between the modeled spectra and measured spectra and estimates the wavelength position. The smile shape can be obtained when the matching process across all columns of the data. The present method is successful applied on the Hyperion data. The value of the wavelength shift is obtained by shape matching of oxygen absorption feature and the characteristics are comparable to that of the prelaunch measurements.

  5. Improving the submicro determination of vanadium in natural water using primary-secondary wavelength spectrophotometry

    International Nuclear Information System (INIS)

    Khongven Gao

    1999-01-01

    In acidic solution and in the presence of ammonium persulfate, the conventional reaction of vanadium(5) with gallic acid to form an orange complex has been used for the improvement of the determination of trace amounts of vanadium in water by the updated method named primary-secondary wavelength spectrophotometry. The results show that the analytical precision and accuracy were improved and gave higher determination sensitivity than ordinary spectrophotometry. The relative standard deviations were less than 5.6 % [ru

  6. Optical Code-Division Multiple-Access and Wavelength Division Multiplexing: Hybrid Scheme Review

    OpenAIRE

    P. Susthitha Menon; Sahbudin Shaari; Isaac A.M. Ashour; Hesham A. Bakarman

    2012-01-01

    Problem statement: Hybrid Optical Code-Division Multiple-Access (OCDMA) and Wavelength-Division Multiplexing (WDM) have flourished as successful schemes for expanding the transmission capacity as well as enhancing the security for OCDMA. However, a comprehensive review related to this hybrid system are lacking currently. Approach: The purpose of this paper is to review the literature on OCDMA-WDM overlay systems, including our hybrid approach of one-dimensional coding of SAC OCDMA with WDM si...

  7. Doubly differential star-16-QAM for fast wavelength switching coherent optical packet transceiver.

    Science.gov (United States)

    Liu, Fan; Lin, Yi; Walsh, Anthony J; Yu, Yonglin; Barry, Liam P

    2018-04-02

    A coherent optical packet transceiver based on doubly differential star 16-ary quadrature amplitude modulation (DD-star-16-QAM) is presented for spectrally and energy efficient reconfigurable networks. The coding and decoding processes for this new modulation format are presented, simulations and experiments are then performed to investigate the performance of the DD-star-16-QAM in static and dynamic scenarios. The static results show that the influence of frequency offset (FO) can be cancelled out by doubly differential (DD) coding and the correction range is only limited by the electronic bandwidth of the receivers. In the dynamic scenario with a time-varying FO and linewidth, the DD-star-16-QAM can overcome the time-varying FO, and the switching time of around 70 ns is determined by the time it takes the dynamic linewidth to reach the requisite level. This format can thus achieve a shorter waiting time after switching tunable lasers than the commonly used square-16-QAM, in which the transmission performance is limited by the frequency transients after the wavelength switch.

  8. Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths.

    Directory of Open Access Journals (Sweden)

    Martin Olofsson

    2010-05-01

    Full Text Available Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function.Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head.In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.

  9. Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths.

    Science.gov (United States)

    Olofsson, Martin; Vallin, Adrian; Jakobsson, Sven; Wiklund, Christer

    2010-05-24

    Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function. Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head. In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.

  10. Short-wavelength out-of-band EUV emission from Sn laser-produced plasma

    Science.gov (United States)

    Torretti, F.; Schupp, R.; Kurilovich, D.; Bayerle, A.; Scheers, J.; Ubachs, W.; Hoekstra, R.; Versolato, O. O.

    2018-02-01

    We present the results of spectroscopic measurements in the extreme ultraviolet regime (7-17 nm) of molten tin microdroplets illuminated by a high-intensity 3 J, 60 ns Nd:YAG laser pulse. The strong 13.5 nm emission from this laser-produced plasma (LPP) is of relevance for next-generation nanolithography machines. Here, we focus on the shorter wavelength features between 7 and 12 nm which have so far remained poorly investigated despite their diagnostic relevance. Using flexible atomic code calculations and local thermodynamic equilibrium arguments, we show that the line features in this region of the spectrum can be explained by transitions from high-lying configurations within the Sn{}8+-Sn{}15+ ions. The dominant transitions for all ions but Sn{}8+ are found to be electric-dipole transitions towards the n = 4 ground state from the core-excited configuration in which a 4p electron is promoted to the 5s subshell. Our results resolve some long-standing spectroscopic issues and provide reliable charge state identification for Sn LPP, which could be employed as a useful tool for diagnostic purposes.

  11. Laser spectroscopy on atoms and ions using short-wavelength radiation

    International Nuclear Information System (INIS)

    Larsson, Joergen.

    1994-05-01

    Radiative properties and energy structures in atoms and ions have been investigated using UV/VUV radiation. In order to obtain radiation at short wavelengths, frequency mixing of pulsed laser radiation in crystals and gases has been performed using recently developed frequency-mixing schemes. To allow the study of radiative lifetimes shorter than the pulses from standard Q-switched lasers, different techniques have been used to obtain sufficiently short pulses. The Hanle effect has been employed following pulsed laser excitation for the same purpose. High-resolution spectroscopic techniques have been adapted for use with the broad-band, pulsed laser sources which are readily available in the UV/VUV spectral region. In order to investigate sources of radiation in the XUV and soft X-ray spectral regions, harmonic generation in rare gases has been studied. The generation of coherent radiation by the interaction between laser radiation and relativistic electrons in a synchrotron storage ring has also been investigated. 60 refs

  12. Wavelength selection in traveling-wave convection in a fluid mixture

    International Nuclear Information System (INIS)

    Surko, C.M.; Eaton, K.D.; Baxter, G.W.; Iwata, K.

    1993-01-01

    The mechanisms by which a one-dimensional pattern of traveling waves changes wavelength (i.e. the Eckhaus instability) is studied in a binary fluid mixture. Propagating wavelength modulations develop when the Rayleigh number of the system is decreased below a wavelength-dependent threshold, commonly referred to as the Eckhaus boundary. These wavelength modulations increase in amplitude and narrow in spatial extent until they trigger the creation or annihilation of convection roll pairs and thereby change the average wavelength of the system. The authors find qualitatively different dynamics for wavelength-increasing events and wavelength-decreasing events; these differences are due to the strong wavelength dependence of the group velocity

  13. Effect of graphene on plasmonic metasurfaces at infrared wavelengths

    Directory of Open Access Journals (Sweden)

    Shinpei Ogawa

    2013-11-01

    Full Text Available Significant enhancement of infrared transmittance by the presence of a graphene layer on a plasmonic metasurface (PLM has been demonstrated. PLMs with different configurations were fabricated, and their transmittance with and without graphene was compared. Selective enhancement by graphene occurred at the plasmon resonance wavelength. The degree of enhancement was found to depend on the width of the gap between the periodic metal regions in the PLM. A maximum enhancement of ∼210% was achieved at a wavelength of 10 μm. The ability to achieve such a drastic increase in transmittance at the plasmon resonant wavelength is expected to lead to improvements in the performance of energy collecting devices and optical sensors.

  14. In-vacuum long-wavelength macromolecular crystallography.

    Science.gov (United States)

    Wagner, Armin; Duman, Ramona; Henderson, Keith; Mykhaylyk, Vitaliy

    2016-03-01

    Structure solution based on the weak anomalous signal from native (protein and DNA) crystals is increasingly being attempted as part of synchrotron experiments. Maximizing the measurable anomalous signal by collecting diffraction data at longer wavelengths presents a series of technical challenges caused by the increased absorption of X-rays and larger diffraction angles. A new beamline at Diamond Light Source has been built specifically for collecting data at wavelengths beyond the capability of other synchrotron macromolecular crystallography beamlines. Here, the theoretical considerations in support of the long-wavelength beamline are outlined and the in-vacuum design of the endstation is discussed, as well as other hardware features aimed at enhancing the accuracy of the diffraction data. The first commissioning results, representing the first in-vacuum protein structure solution, demonstrate the promising potential of the beamline.

  15. Method of stabilizing a laser apparatus with wavelength converter

    DEFF Research Database (Denmark)

    2013-01-01

    and to output the frequency-converted radiation (213), the frequency-converted radiation having at least a second wavelength different from the first wavelength, the diode laser (10) comprising at least a first and a second section (222,223), a first contact (220) for injecting a first current (I1......) into the first section (222), a second contact (221) for injecting a second current (I2) into the second section (223), and means for controlling a temperature of the diode laser; wherein the method comprises monitoring a first parameter indicative of the power content of a dominant lobe of the first radiation......A method of controlling beam quality and stability of a laser apparatus, the laser apparatus comprising, a diode laser (10) providing first radiation of at least a first wavelength, and a frequency conversion unit (12) configured to frequency-convert the first radiation from the diode laser...

  16. Cluster dynamics at different cluster size and incident laser wavelengths

    International Nuclear Information System (INIS)

    Desai, Tara; Bernardinello, Andrea

    2002-01-01

    X-ray emission spectra from aluminum clusters of diameter -0.4 μm and gold clusters of dia. ∼1.25 μm are experimentally studied by irradiating the cluster foil targets with 1.06 μm laser, 10 ns (FWHM) at an intensity ∼10 12 W/cm 2 . Aluminum clusters show a different spectra compared to bulk material whereas gold cluster evolve towards bulk gold. Experimental data are analyzed on the basis of cluster dimension, laser wavelength and pulse duration. PIC simulations are performed to study the behavior of clusters at higher intensity I≥10 17 W/cm 2 for different size of the clusters irradiated at different laser wavelengths. Results indicate the dependence of cluster dynamics on cluster size and incident laser wavelength

  17. Enhanced Plasmonic Wavelength Selective Infrared Emission Combined with Microheater

    Directory of Open Access Journals (Sweden)

    Hiroki Ishihara

    2017-09-01

    Full Text Available The indirect wavelength selective thermal emitter that we have proposed is constructed using a new microheater, demonstrating the enhancement of the emission peak generated by the surface plasmon polariton. The thermal isolation is improved using a 2 μm-thick Si membrane having 3.6 and 5.4 mm outer diameter. The emission at around the wavelength of the absorption band of CO2 gas is enhanced. The absorption signal increases, confirming the suitability for gas sensing. Against input power, the intensity at the peak wavelength shows a steeper increasing ratio than the background intensity. The microheater with higher thermal isolation gives larger peak intensity and its increasing ratio against the input power.

  18. Interferometry on small quantum systems at short wavelength

    International Nuclear Information System (INIS)

    Usenko, Sergey

    2017-01-01

    The present work concentrates on prototypical studies of light-induced correlated many-body dynamics in complex systems. In its course a reflective split-and-delay unit (SDU) for phase-resolved one-color pump-probe experiments with gas phase samples using VUV-XUV laser pulses was built. The collinear propagation of pump and probe pulses is ensured by the special geometry of the SDU and allows to perform phase-resolved (coherent) autocorrelation measurements. The control of the pump-probe delay with attosecond precision is established by a specially developed diagnostic tool based on an in-vacuum white light interferometer that allows to monitor the relative displacement of the SDU reflectors with nanometer resolution. Phase-resolved (interferometric) pump-probe experiments with developed SDU require spatially-resolved imaging of the ionization volume. For this an electron-ion coincidence spectrometer was built. The spectrometer enables coincident detection of photoionization products using velocity map imaging (VMI) technique for electrons and VMI or spatial imaging for ions. In first experiments using the developed SDU and the spectrometer in the ion spatial-imaging mode linear field autocorrelation of free-electron laser pulses at the central wavelength of 38 nm was recorded. A further focus of the work were energy- and time-resolved resonant two-photon ionization experiments using short tunable UV laser pulses on C_6_0 fullerene. The experiments demonstrated that dipole-selective excitation on a timescale faster than the characteristic intramolecular energy dissipation limits the number of accessible excitation pathways and thus results in a narrow resonance. Time-dependent one-color pump-probe study showed that nonadiabatic (vibron) coupling is the dominant energy dissipation mechanism for high-lying electronic excited states in C_6_0.

  19. Interferometry on small quantum systems at short wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Usenko, Sergey

    2017-01-15

    The present work concentrates on prototypical studies of light-induced correlated many-body dynamics in complex systems. In its course a reflective split-and-delay unit (SDU) for phase-resolved one-color pump-probe experiments with gas phase samples using VUV-XUV laser pulses was built. The collinear propagation of pump and probe pulses is ensured by the special geometry of the SDU and allows to perform phase-resolved (coherent) autocorrelation measurements. The control of the pump-probe delay with attosecond precision is established by a specially developed diagnostic tool based on an in-vacuum white light interferometer that allows to monitor the relative displacement of the SDU reflectors with nanometer resolution. Phase-resolved (interferometric) pump-probe experiments with developed SDU require spatially-resolved imaging of the ionization volume. For this an electron-ion coincidence spectrometer was built. The spectrometer enables coincident detection of photoionization products using velocity map imaging (VMI) technique for electrons and VMI or spatial imaging for ions. In first experiments using the developed SDU and the spectrometer in the ion spatial-imaging mode linear field autocorrelation of free-electron laser pulses at the central wavelength of 38 nm was recorded. A further focus of the work were energy- and time-resolved resonant two-photon ionization experiments using short tunable UV laser pulses on C{sub 60} fullerene. The experiments demonstrated that dipole-selective excitation on a timescale faster than the characteristic intramolecular energy dissipation limits the number of accessible excitation pathways and thus results in a narrow resonance. Time-dependent one-color pump-probe study showed that nonadiabatic (vibron) coupling is the dominant energy dissipation mechanism for high-lying electronic excited states in C{sub 60}.

  20. Study and realisation of a femtosecond dye laser operating at different wavelengths. Ultrashort pulses compression and amplification

    International Nuclear Information System (INIS)

    Georges, Patrick

    1989-01-01

    We present the study and the realization of a passively mode-locked dye laser producing pulses shorter than 100 femto-seconds (10 -13 s). In a ring cavity with an amplifier medium (Rhodamine 60) and a saturable absorber (DODCI), a sequence of four prisms controls the group velocity dispersion and allows the generation of very short pulses. Then we have studied the production of femtosecond pulses at other wavelengths directly from the femtosecond dye laser. For the first rime, 60 fs pulses at 685 nm and pulses shorter than 50 fs between 775 nm and 800 nm have been produced by passive mode locking. These near infrared pulses have been used to study the absorption saturation kinetics in semiconductors multiple quantum wells GaAs/GaAlAs. We have observed a singular behavior of the laser operating at 685 nm and analyzed the produced pulses in terms of optical solitons. To perform time resolved spectroscopy with shortest pulses, we have studied a pulse compressor and a multipass amplifier to increase the pulses energy. Pulses of 20 fs and 10 micro-joules (peak power: 0.5 GW) have been obtained at low repetition rate (10 Hz) and pulses of 16 fs and 0.6 micro-joules pulses have been generated at high repetition rate (11 kHz) using a copper vapor laser. These pulses have been used to study the absorption saturation kinetics of an organic dye (the Malachite Green). (author) [fr

  1. Broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity

    Science.gov (United States)

    Li, Q.; Jia, Z. X.; Weng, H. Z.; Li, Z. R.; Yang, Y. D.; Xiao, J. L.; Chen, S. W.; Huang, Y. Z.; Qin, W. P.; Qin, G. S.

    2018-05-01

    We demonstrate broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm and a frequency separation of ~9.28 GHz generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity. By using one continuous-wave laser as the pump source, multi-wavelength Brillouin lasers with an operating wavelength range of 1554–1574 nm were generated via cascaded Brillouin scattering and four-wave mixing. Interestingly, when pumped by two continuous-wave lasers with an appropriate frequency separation, the operating wavelength range of the multi-wavelength Brillouin lasers was increased to 1500–1600 nm due to cavity-enhanced cascaded four-wave mixing among the frequency components generated by two pump lasers in the dual wavelength Brillouin laser cavity.

  2. Three wavelength optical alignment of the Nova laser

    International Nuclear Information System (INIS)

    Swift, C.D.; Bliss, E.S.; Jones, W.A.; Seppala, L.G.

    1983-01-01

    The Nova laser, presently under construction at Lawrence Livermore National Laboratory, will be capable of delivering more than 100 kJ of focused energy to an Inertial Confinement Fusion (ICF) target. Operation at the fundamental wavelength of the laser (1.05 μm) and at the second and third harmonic will be possible. This paper will discuss the optical alignment systems and techniques being implemented to align the laser output to the target at these wavelengths prior to each target irradiation. When experiments require conversion of the laser light to wavelengths of 0.53 μm and 0.35 μm prior to target irradiation, this will be accomplished in harmonic conversion crystals located at the beam entrances to the target chamber. The harmonic alignment system will be capable of introducing colinear alignment beams of all three wavelengths into the laser chains at the final spatial filter. The alignment beam at 1.05 μm will be about three cm in diameter and intense enough to align the conversion crystals. Beams at 0.53 μm and 0.35 μm will be expanded by the spatial filter to full aperture (74 cm) and used to illuminate the target and other alignment aids at the target chamber focus. This harmonic illumination system will include viewing capability as well. A final alignment sensor will be located at the target chamber. It will view images of the chamber focal plane at all three wavelengths. In this way, each beam can be aligned at the desired wavelength to produce the focal pattern required for each target irradiation. The design of the major components in the harmonic alignment system will be described, and a typical alignment sequence for alignment to a target will be presented

  3. Analysis of calibration-free wavelength-scanned wavelength modulation spectroscopy for practical gas sensing using tunable diode lasers

    Science.gov (United States)

    Sun, K.; Chao, X.; Sur, R.; Goldenstein, C. S.; Jeffries, J. B.; Hanson, R. K.

    2013-12-01

    A novel strategy has been developed for analysis of wavelength-scanned, wavelength modulation spectroscopy (WMS) with tunable diode lasers (TDLs). The method simulates WMS signals to compare with measurements to determine gas properties (e.g., temperature, pressure and concentration of the absorbing species). Injection-current-tuned TDLs have simultaneous wavelength and intensity variation, which severely complicates the Fourier expansion of the simulated WMS signal into harmonics of the modulation frequency (fm). The new method differs from previous WMS analysis strategies in two significant ways: (1) the measured laser intensity is used to simulate the transmitted laser intensity and (2) digital lock-in and low-pass filter software is used to expand both simulated and measured transmitted laser intensities into harmonics of the modulation frequency, WMS-nfm (n = 1, 2, 3,…), avoiding the need for an analytic model of intensity modulation or Fourier expansion of the simulated WMS harmonics. This analysis scheme is valid at any optical depth, modulation index, and at all values of scanned-laser wavelength. The method is demonstrated and validated with WMS of H2O dilute in air (1 atm, 296 K, near 1392 nm). WMS-nfm harmonics for n = 1 to 6 are extracted and the simulation and measurements are found in good agreement for the entire WMS lineshape. The use of 1f-normalization strategies to realize calibration-free wavelength-scanned WMS is also discussed.

  4. Cycle 24 COS FUV Internal/External Wavelength Scale Monitor

    Science.gov (United States)

    Fischer, William J.

    2018-02-01

    We report on the monitoring of the COS FUV wavelength scale zero-points during Cycle 24 in program 14855. Select cenwaves were monitored for all FUV gratings at Lifetime Position 3. The target and cenwaves have remained the same since Cycle 21, with a change only to the target acquisition sequence. All measured offsets are within the error goals, although the G140L cenwaves show offsets at the short-wavelength end of segment A that are approaching the tolerance. This behavior will be closely monitored in subsequent iterations of the program.

  5. Intensities of decimetric-wavelength radio recombination lines

    International Nuclear Information System (INIS)

    Parrish, A.; Pankonin, V.

    1975-01-01

    We summarize the intensity results of some of the 221 and 248α recombination-line observations taken with the Arecibo telescope, and report additional results including 166α observations from the NRAO 300-foot (91 m) telescope. The brightness temperatures of these lines increase sharply with wavelength. We show that these results require that the upper levels of the recombining atoms be overpopulated with respect to LTE conditions. The most reasonable interpretation of the results is that the line emission at these decimetric wavelengths is stimulated by a background source of continuum radiation

  6. Single-wavelength functional photoacoustic microscopy in biological tissue.

    Science.gov (United States)

    Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

    2011-03-01

    Recently, we developed a reflection-mode relaxation photoacoustic microscope, based on saturation intensity, to measure picosecond relaxation times using a nanosecond laser. Here, using the different relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, the oxygen saturation was quantified in vivo with single-wavelength photoacoustic microscopy. All previous functional photoacoustic microscopy measurements required imaging with multiple-laser-wavelength measurements to quantify oxygen saturation. Eliminating the need for multiwavelength measurements removes the influence of spectral properties on oxygenation calculations and improves the portability and cost-effectiveness of functional or molecular photoacoustic microscopy.

  7. OMEGA: a short-wavelength laser for fusion experiments

    International Nuclear Information System (INIS)

    Soures, J.M.; Hutchison, R.J.; Jacobs, S.D.; Lund, L.D.; McCrory, R.L.; Richardson, M.C.

    1983-01-01

    The OMEGA, Nd:glass laser facility was constructed for the purpose of investigating the feasibility of direct-drive laser fusion. With 24 beams producing a total energy of 4 kJ or a peak power of 12 TW, OMEGA is capable of nearly uniform illumination of spherical targets. Six of the OMEGA beams have recently been converted to short-wavelength operation (351 nm). In this paper, we discuss details of the system design and performance, with particular emphasis on the frequency-conversion system and multi-wavelength diagnostic system

  8. Wavelength-encoded OCDMA system using opto-VLSI processors.

    Science.gov (United States)

    Aljada, Muhsen; Alameh, Kamal

    2007-07-01

    We propose and experimentally demonstrate a 2.5 Gbits/sper user wavelength-encoded optical code-division multiple-access encoder-decoder structure based on opto-VLSI processing. Each encoder and decoder is constructed using a single 1D opto-very-large-scale-integrated (VLSI) processor in conjunction with a fiber Bragg grating (FBG) array of different Bragg wavelengths. The FBG array spectrally and temporally slices the broadband input pulse into several components and the opto-VLSI processor generates codewords using digital phase holograms. System performance is measured in terms of the autocorrelation and cross-correlation functions as well as the eye diagram.

  9. An algorithm for link restoration of wavelength routing optical networks

    DEFF Research Database (Denmark)

    Limal, Emmanuel; Stubkjær, Kristian

    1999-01-01

    We present an algorithm for restoration of single link failure in wavelength routing multihop optical networks. The algorithm is based on an innovative study of networks using graph theory. It has the following original features: it (i) assigns working and spare channels simultaneously, (ii......) prevents the search for unacceptable routing paths by pointing out channels required for restoration, (iii) offers a high utilization of the capacity resources and (iv) allows a trivial search for the restoration paths. The algorithm is for link restoration of networks without wavelength translation. Its...

  10. Wavelength-encoded OCDMA system using opto-VLSI processors

    Science.gov (United States)

    Aljada, Muhsen; Alameh, Kamal

    2007-07-01

    We propose and experimentally demonstrate a 2.5 Gbits/sper user wavelength-encoded optical code-division multiple-access encoder-decoder structure based on opto-VLSI processing. Each encoder and decoder is constructed using a single 1D opto-very-large-scale-integrated (VLSI) processor in conjunction with a fiber Bragg grating (FBG) array of different Bragg wavelengths. The FBG array spectrally and temporally slices the broadband input pulse into several components and the opto-VLSI processor generates codewords using digital phase holograms. System performance is measured in terms of the autocorrelation and cross-correlation functions as well as the eye diagram.

  11. Aperture Mask for Unambiguous Parity Determination in Long Wavelength Imagers

    Science.gov (United States)

    Bos, Brent

    2011-01-01

    A document discusses a new parity pupil mask design that allows users to unambiguously determine the image space coordinate system of all the James Webb Space Telescope (JWST) science instruments by using two out-of-focus images. This is an improvement over existing mask designs that could not completely eliminate the coordinate system parity ambiguity at a wavelength of 5.6 microns. To mitigate the problem of how the presence of diffraction artifacts can obscure the pupil mask detail, this innovation has been created with specifically designed edge features so that the image space coordinate system parity can be determined in the presence of diffraction, even at long wavelengths.

  12. Aluminum nitride nanophotonic circuits operating at ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Stegmaier, M.; Ebert, J.; Pernice, W. H. P., E-mail: wolfram.pernice@kit.edu [Institute of Nanotechnology, Karlsruhe Institute of Technology, 76133 Karlsruhe (Germany); Meckbach, J. M.; Ilin, K.; Siegel, M. [Institute of Micro- und Nanoelectronic Systems, Karlsruhe Institute of Technology, 76187 Karlsruhe (Germany)

    2014-03-03

    Aluminum nitride (AlN) has recently emerged as a promising material for integrated photonics due to a large bandgap and attractive optical properties. Exploiting the wideband transparency, we demonstrate waveguiding in AlN-on-Insulator circuits from near-infrared to ultraviolet wavelengths using nanophotonic components with dimensions down to 40 nm. By measuring the propagation loss over a wide spectral range, we conclude that both scattering and absorption of AlN-intrinsic defects contribute to strong attenuation at short wavelengths, thus providing guidelines for future improvements in thin-film deposition and circuit fabrication.

  13. MODIS Aqua Optical Throughput Degradation Impact on Relative Spectral Response and Calibration on Ocean Color Products

    Science.gov (United States)

    Lee, Shihyan; Meister, Gerhard

    2017-01-01

    Since Moderate Resolution Imaging Spectroradiometer Aqua's launch in 2002, the radiometric system gains of the reflective solar bands have been degrading, indicating changes in the systems optical throughput. To estimate the optical throughput degradation, the electronic gain changes were estimated and removed from the measured system gain. The derived optical throughput degradation shows a rate that is much faster in the shorter wavelengths than the longer wavelengths. The wavelength-dependent optical throughput degradation modulated the relative spectral response (RSR) of the bands. In addition, the optical degradation is also scan angle-dependent due to large changes in response versus the scan angle over time. We estimated the modulated RSR as a function of time and scan angles and its impacts on sensor radiometric calibration for the ocean science. Our results show that the calibration bias could be up to 1.8 % for band 8 (412 nm) due to its larger out-of-band response. For the other ocean bands, the calibration biases are much smaller with magnitudes at least one order smaller.

  14. Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, M.; Hamadeh, H., E-mail: scientific@aec.org.sy [Department of Physics, Atomic Energy Commission of Syria (AECS), P.O. Box 6091 Damascus (Syrian Arab Republic)

    2009-08-31

    The effect of low power density of {approx} 5 {mu}W/cm{sup 2} monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Two-peak PL 'red' and 'green' is resolved in PS samples etched under blue-green wavelength illumination; 480, 533 and 580 nm. It is found that the weight of 'green' PL has maxima for the sample illuminated with 533 nm wavelength. Whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit 'green' PL band, but shows considerable enhancement in the 'red' PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS.

  15. Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

    International Nuclear Information System (INIS)

    Naddaf, M.; Hamadeh, H.

    2010-01-01

    The effect of low power density of ∼5 μWcm - 2 monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Tow peak PL red and green is resolved in PS samples etched under blue-green wavelength illumination; 480,533 and 580 nm. It is found that the weight of green PL has maxima for the sample illuminated with 533 nm wavelength whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit green PL band, but shows considerable enhancement in the red PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS. (author)

  16. Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

    International Nuclear Information System (INIS)

    Naddaf, M.; Hamadeh, H.

    2009-01-01

    The effect of low power density of ∼ 5 μW/cm 2 monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Two-peak PL 'red' and 'green' is resolved in PS samples etched under blue-green wavelength illumination; 480, 533 and 580 nm. It is found that the weight of 'green' PL has maxima for the sample illuminated with 533 nm wavelength. Whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit 'green' PL band, but shows considerable enhancement in the 'red' PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS.

  17. Enhanced Deformation of Azobenzene-Modified Liquid Crystal Polymers under Dual Wavelength Exposure: A Photophysical Model

    Science.gov (United States)

    Liu, Ling; Onck, Patrick R.

    2017-08-01

    Azobenzene-embedded liquid crystal polymers can undergo mechanical deformation in response to ultraviolet (UV) light. The natural rodlike trans state azobenzene absorbs UV light and isomerizes to a bentlike cis state, which disturbs the order of the polymer network, leading to an anisotropic deformation. The current consensus is that the magnitude of the photoinduced deformation is related to the statistical building up of molecules in the cis state. However, a recent experimental study [Liu and Broer, Nat. Commun. 6 8334 (2015)., 10.1038/ncomms9334] shows that a drastic (fourfold) increase of the photoinduced deformation can be generated by exposing the samples simultaneously to 365 nm (UV) and 455 nm (visible) light. To elucidate the physical mechanism that drives this increase, we develop a two-light attenuation model and an optomechanical constitutive relation that not only accounts for the statistical accumulation of cis azobenzenes, but also for the dynamic trans-cis-trans oscillatory isomerization process. Our experimentally calibrated model predicts that the optimal single-wavelength exposure is 395 nm light, a pronounced shift towards the visible spectrum. In addition, we identify a range of optimal combinations of two-wavelength lights that generate a favorable response for a given amount of injected energy. Our model provides mechanistic insight into the different (multi)wavelength exposures used in experiments and, at the same time, opens new avenues towards enhanced, multiwavelength optomechanical behavior.

  18. Absolute distance measurement with micrometer accuracy using a Michelson interferometer and the iterative synthetic wavelength principle.

    Science.gov (United States)

    Alzahrani, Khaled; Burton, David; Lilley, Francis; Gdeisat, Munther; Bezombes, Frederic; Qudeisat, Mohammad

    2012-02-27

    We present a novel system that can measure absolute distances of up to 300 mm with an uncertainty of the order of one micrometer, within a timeframe of 40 seconds. The proposed system uses a Michelson interferometer, a tunable laser, a wavelength meter and a computer for analysis. The principle of synthetic wave creation is used in a novel way in that the system employs an initial low precision estimate of the distance, obtained using a triangulation, or time-of-flight, laser system, or similar, and then iterates through a sequence of progressively smaller synthetic wavelengths until it reaches micrometer uncertainties in the determination of the distance. A further novel feature of the system is its use of Fourier transform phase analysis techniques to achieve sub-wavelength accuracy. This method has the major advantages of being relatively simple to realize, offering demonstrated high relative precisions better than 5 × 10(-5). Finally, the fact that this device does not require a continuous line-of-sight to the target as is the case with other configurations offers significant advantages.

  19. Line ratios and wavelengths of helium-like argon n=2 satellite transitions and resonance lines

    International Nuclear Information System (INIS)

    Biedermann, C.; Radtke, R.; Fournier, K.

    2003-01-01

    The characteristic X-ray emission from helium-like argon was investigated as a mean to diagnose hot plasmas. We have measured the radiation from n=2-1 parent lines and from KLn dielectronic recombination satellites with high wavelength resolution as function of the excitation energy using the Berlin Electron Beam Ion Trap. Values of wavelength relative to the resonance and forbidden line are tabulated and compared with references. The line intensity observed over a wide range of excitation energies is weighted with a Maxwellian electron-energy distribution to analyze line ratios as function of plasma temperature. Line ratios (j+z)/w and k/w compare nicely with theoretical predictions and demonstrate their applicability as temperature diagnostic. The ratio z/(x+y) shows not to depend on the electron density

  20. All-Optical Regeneration System for Optical Wavelength Division Multiplexed Communication Systems

    DEFF Research Database (Denmark)

    2014-01-01

    The invention relates to an all-optical regeneration system for regeneration of optical wavelength division multiplexed WDM data signals in an optical WDM communication system. The system comprises a WDM-to-Optical time domain multiplexing OTDM, WDM-to-OTDM, converter, capable of converting....... The system additionally comprises an OTDM-to-WDM converter for converting the output OTDM data signal to an output WDM data signal. An input of the all-optical regenerator unit is in optical communication with an output of the WDM-to-OTDM converter, and an output of the all-optical regenerator unit...... an input WDM data signal comprising multiple wavelength channels into an input OTDM data signal comprising multiple time multiplexed time channels. The system further comprises an all-optical regenerator unit being configured for regenerating the input OTDM data signal into an output OTDM data signal...

  1. Liquid argon scintillation detection utilizing wavelength-shifting plates and light guides

    Science.gov (United States)

    Howard, B.

    2018-02-01

    In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

  2. Liquid Argon Scintillation Detection Utilizing Wavelength-Shifting Plates and Light Guides

    Energy Technology Data Exchange (ETDEWEB)

    Howard, B. [Indiana U.

    2018-02-06

    In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

  3. Simultaneous wavelength and orbital angular momentum demultiplexing using tunable MEMS-based Fabry-Perot filter

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir; Porfirev, Alexey P.; Gurbatov, Stanislav O.

    2017-01-01

    In this paper, we experimentally demonstrate simultaneous wavelength and orbital angular momentum (OAM) multiplexing/demultiplexing of 10 Gbit/s data streams using a new on-chip micro-component-tunable MEMS-based Fabry-Perot filter integrated with a spiral phase plate. In the experiment, two......, maximum power penalties at the HD-FEC BER threshold relative to the 0.8 nm wavelength spacing read 0.83, 0.84 and 1.15 dB when multiplexing a Gaussian beam and OAM beams of 1st, 2nd and 3rd orders respectively. The novelty and impact of the proposed filter design is in providing practical, integrable...

  4. Urban blackbirds have shorter telomeres

    NARCIS (Netherlands)

    Ibanez-Alamo, Juan Diego; Pineda-Pampliega, Javier; Thomson, Robert L.; Aguirre, Jose I.; Diez-Fernandez, Alazne; Faivre, Bruno; Figuerola, Jordi; Verhulst, Simon

    Urbanization, one of the most extreme human-induced environmental changes, represents a major challenge for many organisms. Anthropogenic habitats can have opposing effects on different fitness components, for example, by decreasing starvation risk but also health status. Assessment of the net

  5. Choice of Eye-Safe Radiation Wavelength in UV and Near IR Spectral Bands for Remote Sensing

    Directory of Open Access Journals (Sweden)

    M. L. Belov

    2016-01-01

    Full Text Available The introduction of laser remote sensing systems carries a particular risk to the human’s sense of vision. A structure of the eye, and especially the retina, is the main critical organ as related to the laser radiation.The work uses the optical models of the atmosphere, correctly working in both the UV and the near-IR band, to select the eye-safe radiation wavelengths in the UV (0.355 m and near-IR (~ 1.54 and ~ 2 m spectral bands from the point of view of recorded lidar signal value to fulfill the tasks of laser sensing the natural formations and laser aerosol sensing in the atmosphere.It is shown that the remote sensing lasers with appropriate characteristics can be selected both in the UV band (at a wavelength of 0.355 μm and in the near-IR band (at wavelengths of 1.54 ~ or ~ 2 μm.Molecular scattering has its maximum (for the selected wavelength at a wavelength of 0.355 μm in the UV band, and the minimum at the wavelengths of 1.54 and 2.09 μm in the near -IR band. The main contribution to the molecular absorption at a wavelength of 0.355 μm is made by ozone. In the near-IR spectral band the radiation is absorbed due to water vapor and carbon dioxide.Calculations show that the total effect of the molecular absorption and scattering has no influence on radiation transmission for both the wavelength of 0.355 μm in the UV band, and the wavelengths of 1.54 and 2.09 μm in the near-IR band for sensing trails ~ 1 km.One of the main factors of laser radiation attenuation in the Earth's atmosphere is radiation scattering by aerosol particles.The results of calculations at wavelengths of 0.355 μm, 1.54 μm and 2.09 μm for the several models of the atmosphere show that a choice of the most effective (in terms of the recorded signal of lidar and eye-safe radiation wavelength depends strongly on the task of sensing.To fulfill the task of laser sensing the natural formations, among the eye-safe wavelengths there is one significantly advantageous

  6. Systemic lupus erythematosus and vitamin D deficiency are associated with shorter telomere length among African Americans: a case-control study.

    Directory of Open Access Journals (Sweden)

    Brett M Hoffecker

    Full Text Available Systemic lupus erythematosus (SLE is a chronic systemic autoimmune disease that disproportionately affects African American females. The causes of SLE are unknown but postulated to be a combination of genetic predisposition and environmental triggers. Vitamin D deficiency is one of the possible environmental triggers. In this study we evaluated relationships between vitamin D status, cellular aging (telomere length and anti-telomere antibodies among African American Gullah women with SLE. The study population included African American female SLE patients and unaffected controls from the Sea Island region of South Carolina. Serum 25-hydroxyvitamin D levels were measured using a nonchromatographic radioimmunoassay. Telomere length was measured in genomic DNA of peripheral blood mononuclear cells (PBMCs by monochrome multiplex quantitative PCR. Anti-telomere antibody levels were measured by enzyme-linked immunosorbent assay (ELISA. Patients with SLE had significantly shorter telomeres and higher anti-telomere antibody titers compared to age- and gender-matched unaffected controls. There was a positive correlation between anti-telomere antibody levels and disease activity among patients and a significant correlation of shorter telomeres with lower 25-hydroxyvitamin D levels in both patients and controls. In follow-up examination of a subset of the patients, the patients who remained vitamin D deficient tended to have shorter telomeres than those patients whose 25-hydroxyvitamin D levels were repleted. Increasing 25-hydroxyvitamin D levels in African American patients with SLE may be beneficial in maintaining telomere length and preventing cellular aging. Moreover, anti-telomere antibody levels may be a promising biomarker of SLE status and disease activity.

  7. Long-Term Costs and Health Consequences of Issuing Shorter Duration Prescriptions for Patients with Chronic Health Conditions in the English NHS.

    Science.gov (United States)

    Martin, Adam; Payne, Rupert; Wilson, Edward Cf

    2018-06-01

    The National Health Service (NHS) in England spends over £9 billion on prescription medicines dispensed in primary care, of which over two-thirds is accounted for by repeat prescriptions. Recently, GPs in England have been urged to limit the duration of repeat prescriptions, where clinically appropriate, to 28 days to reduce wastage and hence contain costs. However, shorter prescriptions will increase transaction costs and thus may not be cost saving. Furthermore, there is evidence to suggest that shorter prescriptions are associated with lower adherence, which would be expected to lead to lower clinical benefit. The objective of this study is to estimate the cost-effectiveness of 3-month versus 28-day repeat prescriptions from the perspective of the NHS. We adapted three previously developed UK policy-relevant models, incorporating transaction (dispensing fees, prescriber time) and drug wastage costs associated with 3-month and 28-day prescriptions in three case studies: antihypertensive medications for prevention of cardiovascular events; drugs to improve glycaemic control in patients with type 2 diabetes; and treatments for depression. In all cases, 3-month prescriptions were associated with lower costs and higher QALYs than 28-day prescriptions. This is driven by assumptions that higher adherence leads to improved disease control, lower costs and improved QALYs. Longer repeat prescriptions may be cost-effective compared with shorter ones. However, the quality of the evidence base on which this modelling is based is poor. Any policy rollout should be within the context of a trial such as a stepped-wedge cluster design.

  8. Organic wavelength selective mirrors for luminescent solar concentrators

    NARCIS (Netherlands)

    Verbunt, P.P.C.; Debije, M.G.; Broer, D.J.; Bastiaansen, C.W.M.; Boer, de D.K.G.; Wehrspohn, R.; Gombert, A.

    2012-01-01

    Organic polymeric chiral nematic liquid crystalline (cholesteric) wavelength selective mirrors can increase the efficiency of luminescent solar concentrators (LSCs) when they are illuminated with direct sunlight normal to the device. However, due to the angular dependence of the reflection band, at

  9. Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

    International Nuclear Information System (INIS)

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron L. C.; Kristensen, Anders

    2014-01-01

    A class of photonic crystal resonant reflectors known as guided mode resonant filters are optical structures that are widely used in the field of refractive index sensing, particularly in biosensing. For the purposes of understanding and design, their behavior has traditionally been modeled numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken into account. Furthermore, it is demonstrated that the model is valid beyond the limit of low grating modulation, for periodically discontinuous waveguide layers, high refractive index contrasts, and highly dispersive media.

  10. [Wavelength Selection in Hemolytic Evaluation Systems with Spectrophotometry Detection].

    Science.gov (United States)

    Zhang, Hong; Su, Baochang; Ye, Xunda; Luo, Man

    2016-04-01

    Spectrophotometry is a simple hemolytic evaluation method commonly used in new drugs,biomedical materials and blood products.It is for the quantitative analysis of the characteristic absorption peaks of hemoglobin.Therefore,it is essential to select the correct detection wavelength when the evaluation system has influences on the conformation of hemoglobin.Based on the study of changes in the characteristic peaks over time of the hemolysis supernatant in four systems,namely,cell culture medium,phosphate buffered saline(PBS),physiological saline and banked blood preservation solution,using continuous wavelength scanning,the selections of detection wavelength were proposed as follows.In the cell culture medium system,the wavelength of 415 nm should be selected within 4h;,near 408 nm should be selected within 4~72h.In PBS system,within 4h,541 nm,577nm or 415 nm should be selected;4~72h,541 nm,577nm or near 406 nm should be selected.In physiological saline system,within 4h,414 nm should be selected;4~72h,near 405 nm should be selected;within 12 h,541nm or 577 nm could also be selected.In banked blood preservation solution system,within 72 h,415nm,540 nm or 576 nm should be selected.

  11. Metallic nano-cavity lasers at near infrared wavelengths

    NARCIS (Netherlands)

    Hill, M.T.; Stockman, M.I.

    2009-01-01

    There has been considerable interest in nano-cavity lasers, both from a scientific perspective for investigating fundamental properties of lasers and cavities, and also to produce smaller and better lasers for low-power applications. Light confinement on a wavelength scale has been reported in

  12. Pilot tones in WDM networks with wavelength converters

    DEFF Research Database (Denmark)

    Kloch, Allan; Mikkelsen, Benny; Stubkjær, Kristian

    1997-01-01

    Here we investigate the transmission of a pilot tone through an interferometric wavelength converter (IWC) in conjunction with a 2.5 Gbit/s experiment. The pilot tone is added by sinusoidal modulation of the bias current to the signal laser. After the IWC (Michelson interferometer) the converted...

  13. Wavelength selection method with standard deviation: application to pulse oximetry.

    Science.gov (United States)

    Vazquez-Jaccaud, Camille; Paez, Gonzalo; Strojnik, Marija

    2011-07-01

    Near-infrared spectroscopy provides useful biological information after the radiation has penetrated through the tissue, within the therapeutic window. One of the significant shortcomings of the current applications of spectroscopic techniques to a live subject is that the subject may be uncooperative and the sample undergoes significant temporal variations, due to his health status that, from radiometric point of view, introduce measurement noise. We describe a novel wavelength selection method for monitoring, based on a standard deviation map, that allows low-noise sensitivity. It may be used with spectral transillumination, transmission, or reflection signals, including those corrupted by noise and unavoidable temporal effects. We apply it to the selection of two wavelengths for the case of pulse oximetry. Using spectroscopic data, we generate a map of standard deviation that we propose as a figure-of-merit in the presence of the noise introduced by the living subject. Even in the presence of diverse sources of noise, we identify four wavelength domains with standard deviation, minimally sensitive to temporal noise, and two wavelengths domains with low sensitivity to temporal noise.

  14. Single-wavelength functional photoacoustic microscopy in biological tissue

    OpenAIRE

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2011-01-01

    Recently, we developed a reflection-mode relaxation photoacoustic microscope, based on saturation intensity, to measure picosecond relaxation times using a nanosecond laser. Here, using the different relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, the oxygen saturation was quantified in vivo with single-wavelength photoacoustic microscopy. All previous functional photoacoustic microscopy measurements required ima...

  15. POF based glucose sensor incorporating grating wavelength filters

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Aasmul, Søren; Bang, Ole

    2014-01-01

    AND RESEARCH IN POLYMER OPTICAL DEVICES; TRIPOD. Within the domain of TRIPOD, research is conducted on "Plastic Optical Fiber based Glucose Sensors Incorporating Grating Wavelength Filters". Research will be focused to optimized fiber tips for better coupling efficiency, reducing the response time of sensor...

  16. Compact titanium dioxide waveguides with high nonlinearity at telecommunication wavelengths

    DEFF Research Database (Denmark)

    Guan, Xiaowei; Hu, Hao; Oxenløwe, Leif Katsuo

    2018-01-01

    .43 mu m(2)) and a low loss (5.4 +/- 1 dB/cm) at telecommunication wavelengths around 1550 nm have been fabricated and measured. A microring resonator having a 50 mu m radius has been measured to have a loaded quality factor of 53500. Four-wave mixing experiments reveal a nonlinear parameter...

  17. Agility of Felix Regarding Wavelength and Micropulse Shape

    NARCIS (Netherlands)

    Bakker, R. J.; van der Geer, C. A. J.; Jaroszynski, D. A.; van der Meer, A. F. G.; Oepts, D.; van Amersfoort, P. W.; Anderegg, V.; van Son, P. C.

    1993-01-01

    The user-facility FELIX employs two FELs together covering the spectral range from 6.5 to 110 mum. Adjustment of the undulator strength permits wavelength tuning over a factor of two within two minutes while continuously providing several kilowatts of output power. As FELIX combines short electron

  18. Nonlinear propagation of short wavelength drift-Alfven waves

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

  19. Enabling Searches on Wavelengths in a Hyperspectral Indices Database

    Science.gov (United States)

    Piñuela, F.; Cerra, D.; Müller, R.

    2017-10-01

    Spectral indices derived from hyperspectral reflectance measurements are powerful tools to estimate physical parameters in a non-destructive and precise way for several fields of applications, among others vegetation health analysis, coastal and deep water constituents, geology, and atmosphere composition. In the last years, several micro-hyperspectral sensors have appeared, with both full-frame and push-broom acquisition technologies, while in the near future several hyperspectral spaceborne missions are planned to be launched. This is fostering the use of hyperspectral data in basic and applied research causing a large number of spectral indices to be defined and used in various applications. Ad hoc search engines are therefore needed to retrieve the most appropriate indices for a given application. In traditional systems, query input parameters are limited to alphanumeric strings, while characteristics such as spectral range/ bandwidth are not used in any existing search engine. Such information would be relevant, as it enables an inverse type of search: given the spectral capabilities of a given sensor or a specific spectral band, find all indices which can be derived from it. This paper describes a tool which enables a search as described above, by using the central wavelength or spectral range used by a given index as a search parameter. This offers the ability to manage numeric wavelength ranges in order to select indices which work at best in a given set of wavelengths or wavelength ranges.

  20. Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

    DEFF Research Database (Denmark)

    Lawætz, Peter

    1969-01-01

    The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering...... of the very-short-range nature of interactions in a covalent semiconductor....

  1. Wavelength-converted long-reach reconfigurable optical access network

    NARCIS (Netherlands)

    Tran, N.C.; Tangdiongga, E.; Koonen, A.M.J.

    2012-01-01

    Next generation optical access networks should not only increase the capacity but also be able to redistribute the capacity on the fly in order to manage more fluctuated traffic patterns. Wavelength reconfigurability is the instrument to enable such capability of network-wide bandwidth

  2. Vertical integration of dual wavelength index guided lasers

    NARCIS (Netherlands)

    Karouta, F.; Tan, H.H.; Jagadish, C.; Roy, van B.H.

    1999-01-01

    The vertical integration of two GaAs-based lasers operating at different wavelengths has been achieved with the use of re-growth technology. A V-channel substrate inner stripe structure was used for the bottom laser and a ridge waveguide for the top laser. Both lasers shared a common electrode and

  3. Recent advances in long wavelength quantum dot lasers and amplifiers

    NARCIS (Netherlands)

    Nötzel, R.; Bente, E.A.J.M.; Smit, M.K.; Dorren, H.J.S.

    2009-01-01

    We demonstrate 1.55-µm InAs/InGaAsP/InP (100) quantum dot (QD) shallow and deep etched Fabry-Pérot and ring lasers, micro-ring lasers, mode-locked lasers, Butt-joint integrated lasers, polarization control of gain, and wavelength conversion in QD amplifiers.

  4. Wavelength-dependent Faraday–Tyndall effect on laser-induced microbubble in gold colloid

    International Nuclear Information System (INIS)

    Liaw, Jiunn-Woei; Tsai, Shiao-Wen; Lin, Hung-Hsun; Yen, Tzu-Chen; Chen, Bae-Renn

    2012-01-01

    The cavitation microbubbles in dilute gold colloids of different concentrations (2–10 ppm) induced by a focused nanosecond-pulsed laser beam were measured and characterized at different wavelengths by using the passive and active ultrasound measurements. Three colloids with gold nanoparticles (GNPs) of different sizes (10, 45, and 75 nm) were used for experiment. The results show that the lifespan of the microbubble is reduced as the concentration of GNP increases, particularly at the wavelength of 532 nm, the surface plasmon resonance (SPR) of GNP. In contrast, at the off-resonant wavelength (e.g. 700 nm), the lifespan reduction is relatively small. This wavelength-dependent cavitation is attributed to the Faraday–Tyndall effect, a strong light scattering by GNPs. A slight defocusing of the Gaussian beam in gold colloid was proposed. Hence, the waist of the focused beam increases to reduce the optical breakdown in gold colloid. For simplicity, a linear relation between the incremental waist radius of Gaussian beam and the concentration of GNP was assumed. According to this formulation, the theoretical results are consistent with the experimental ones. In addition, the dynamics of the microbubble in gold colloid measured by the active ultrasound method agree with the Rayleigh–Plesset model. -- Highlights: ► The Faraday–Tyndall effect of gold colloid on laser induced microbubble is studied. ► Faraday–Tyndall effect of gold colloid causes the defocusing of laser beam. ► Lifespan of the microbubble is reduced as the concentration of GNP increases. ► Light scattering of laser beam at the surface plasmon resonance of GNP is the maximum.

  5. Interstitial lung abnormalities in treatment-naïve advanced non-small-cell lung cancer patients are associated with shorter survival

    Energy Technology Data Exchange (ETDEWEB)

    Nishino, Mizuki, E-mail: Mizuki_Nishino@DFCI.HARVARD.EDU [Department of Radiology, Brigham and Women' s Hospital, 75 Francis St., Boston, MA 02115 (United States); Department of Imaging, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02215 (United States); Cardarella, Stephanie [Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02215, (United States); Dahlberg, Suzanne E. [Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02215 (United States); Araki, Tetsuro [Department of Radiology, Brigham and Women' s Hospital, 75 Francis St., Boston, MA 02115 (United States); Lydon, Christine; Jackman, David M.; Rabin, Michael S. [Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02215, (United States); Hatabu, Hiroto [Department of Radiology, Brigham and Women' s Hospital, 75 Francis St., Boston, MA 02115 (United States); Johnson, Bruce E. [Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02215, (United States)

    2015-05-15

    Highlights: • Interstitial lung abnormalities were present in 14% of stage IV NSCLC patients. • ILA was more common in older patients with heavier smoking history. • ILA was associated with shorter survival after adjusting for smoking and therapy. • ILA could be an additional independent marker for survival in advanced NSCLC. - Abstract: Objective: Interstitial lung diseases are associated with increased risk of lung cancer. The prevalence of ILA at diagnosis of advanced non-small-cell lung cancer (NSCLC) and its impact on overall survival (OS) remain to be investigated. Materials and method: The study included 120 treatment-naïve stage IV NSCLC patients (53 males, 67 females). ILA was scored on CT prior to any systemic therapy using a 4-point scale [0 = no evidence of ILA, 1 = equivocal for ILA, 2 = suspicious for ILA, 3 = ILA] by a sequential reading method previously reported. ILA scores of 2 or 3 indicated the presence of ILA. Results: ILA was present in 17 patients (14%) with advanced NSCLC prior to any treatment (score3: n = 2, score2: n = 15). These 17 patients were significantly older (median age: 69 vs. 63, p = 0.04) and had a heavier smoking history (median: 40 vs. 15.5 pack-year, p = 0.003) than those with ILA score 0 or 1. Higher ILA scores were associated with shorter OS (p = 0.001). Median OS of the 17 patients with ILA was 7.2 months [95%CI: 2.9–9.4] compared to 14.8 months [95%CI: 11.1–18.4] in patients with ILA score 0 or 1 (p = 0.002). In a multivariate model, the presence of ILA remained significant for increased risk for death (HR = 2.09, p = 0.028) after adjusting for first-line systemic therapy (chemotherapy, p < 0.001; TKI, p < 0.001; each compared to no therapy) and pack years of smoking (p = 0.40). Conclusion: Radiographic ILA was present in 14% of treatment-naïve advanced NSCLC patients. Higher ILA scores were associated with shorter OS, indicating that ILA could be a marker of shorter survival in advanced NSCLC.

  6. The Glycated Albumin (GA) to HbA1c Ratio Reflects Shorter-Term Glycemic Control than GA: Analysis of Patients with Fulminant Type 1 Diabetes.

    Science.gov (United States)

    Koga, Masafumi; Inada, Shinya; Nakao, Taisei; Kawamori, Ryuzo; Kasayama, Soji

    2017-01-01

    Glycated albumin (GA) reflects shorter-term glycemic control than HbA1c. We have reported that HbA1c is paradoxically increased in diabetic patients whose glycemic control deteriorated before ameliorating. In this study, we analyzed paradoxical increases of glycemic control indicators after treatment in patients with fulminant type 1 diabetes (FT1D). We also investigated whether the GA/HbA1c ratio may reflect shorter-term glycemic control than GA. Five FT1D patients whose post-treatment HbA1c and GA levels were measured were enrolled. We also used a formula to estimate HbA1c and GA from the fictitious models of changes in plasma glucose in FT1D patients. In this model, the periods during which HbA1c, GA, and the GA/HbA1c ratio were higher than at the first visit were compared. In addition, the half-life for the GA/HbA1c ratio was calculated in accordance with the half-lives for HbA1c and GA (36 and 14 days, respectively). In all FT1D patients, HbA1c levels 2-4 weeks after treatment were increased, with three patients (60%) experiencing an increase of GA levels. In contrast, an increase of the GA/HbA1c ratio was observed in only one patient. In all of the different models of changes in plasma glucose in FT1D patients, the length of time during which the values were higher than at the first visit was in the order of HbA1c > GA > GA/HbA1c ratio. The half-life for the GA/HbA1c ratio was 9 days, shorter than GA. These findings suggest that the GA/HbA1c ratio reflects shorter-term glycemic control than GA. © 2016 Wiley Periodicals, Inc.

  7. All optical wavelength conversion and parametric amplification in Ti:PPLN channel waveguides for telecommunication applications

    Energy Technology Data Exchange (ETDEWEB)

    Nouroozi, Rahman

    2010-10-19

    Efficient ultra-fast integrated all-optical wavelength converters and parametric amplifiers transparent to the polarization, phase, and modulation-level and -format are investigated. The devices take advantage of the optical nonlinearity of Ti:PPLN waveguides exploiting difference frequency generation (DFG). In a DFG, the signal ({lambda}{sub s}) is mixed with a pump ({lambda}{sub p}) to generate a wavelength shifted idler (1/{lambda}{sub i}=1/{lambda}{sub p}-1/{lambda}{sub s}). Efficient generation of the pump in Ti:PPLN channel guides is investigated using different approaches. In the waveguide resonators, first a resonance of the fundamental wave alone is considered. It is shown that the maximum power enhancement of the fundamental wave, and therefore the maximum second-harmonic generation (SHG) efficiency, can be achieved with low loss matched resonators. By this way, SHG efficiency of {proportional_to}10300%/W (10.3 %/mW) has been achieved in a 65 mm long waveguide resonator. Its operation for cSHG/DFG requires narrowband reflector for fundamental wave only. Thus, the SH (pump) wave resonator is investigated. The SH-wave resonator enhances the intracavity SH power only. Based on this scheme, an improvement of {proportional_to}10 dB for cSHG/DFG based wavelength conversion efficiency has been achieved with 50 mW of coupled fundamental power in a 30 mm long Ti:PPLN. However, operation was limited to relatively small fundamental power levels (<50 mW) due to the onset of photorefractive instabilities destroying the cavity stabilization. The cSHG/DFG efficiency can be considerably improved by using a double-pass configuration in which all the interacting waves were reflected by a broadband dielectric mirror deposited on the one endface of the waveguide. Three different approaches are investigated and up to 9 dB improvement of the wavelength conversion efficiency in comparison with the single-pass configuration is achieved. Polarization-insensitive wavelength

  8. Long-wavelength photonic integrated circuits and avalanche photodetectors

    Science.gov (United States)

    Tsou, Yi-Jen D.; Zaytsev, Sergey; Pauchard, Alexandre; Hummel, Steve; Lo, Yu-Hwa

    2001-10-01

    Fast-growing internet traffic volume require high data communication bandwidth over longer distances. Access network bottlenecks put pressure on short-range (SR) telecommunication systems. To effectively address these datacom and telecom market needs, low-cost, high-speed laser modules at 1310 to 1550 nm wavelengths and avalanche photodetectors are required. The great success of GaAs 850nm VCSEls for Gb/s Ethernet has motivated efforts to extend VCSEL technology to longer wavelengths in the 1310 and 1550 nm regimes. However, the technological challenges associated with materials for long wavelength VCSELs are tremendous. Even with recent advances in this area, it is believed that significant additional development is necessary before long wavelength VCSELs that meet commercial specifications will be widely available. In addition, the more stringent OC192 and OC768 specifications for single-mode fiber (SMF) datacom may require more than just a long wavelength laser diode, VCSEL or not, to address numerous cost and performance issues. We believe that photonic integrated circuits (PICs), which compactly integrate surface-emitting lasers with additional active and passive optical components with extended functionality, will provide the best solutions to today's problems. Photonic integrated circuits have been investigated for more than a decade. However, they have produced limited commercial impact to date primarily because the highly complicated fabrication processes produce significant yield and device performance issues. In this presentation, we will discuss a new technology platform of InP-based PICs compatible with surface-emitting laser technology, as well as a high data rate externally modulated laser module. Avalanche photodetectors (APDs) are the key component in the receiver to achieve high data rate over long transmission distance because of their high sensitivity and large gain- bandwidth product. We have used wafer fusion technology to achieve In

  9. Wavelength dependence of pyrimidine dimer formation in DNA of human skin irradiated in situ with ultraviolet light

    International Nuclear Information System (INIS)

    Freeman, S.E.; Hacham, H.; Gange, R.W.; Maytum, D.J.; Sutherland, J.C.; Sutherland, B.M.

    1989-01-01

    The UV components of sunlight are believed to be a major cause of human skin caner, and DNA is though to be the principal molecular target. Alterations of the intensity and wavelength distribution of solar UV radiation reaching the surface of the earth, for example by depletion of stratospheric ozone, will change the effectiveness of solar radiation in damaging DNA in human skin. Evaluation of the magnitude of such effects requires knowledge of the altered sunlight spectrum and of the action spectrum for damaging DNA in human skin. The authors have determined an action spectrum for the frequency of pyrimidine dimer formation induced in the DNA of human skin per unit dose of UV incident on the skin surface. The peak of this action spectrum is near 300 nm and decreases rapidly at both longer and shorter wavelengths. The decrease in the action spectrum for wavelengths <300 nm is attributed to the absorption of the upper layers of the skin. Convolution of the dimer action spectrum with the solar spectra corresponding to a solar angle of 40 degree under current levels of stratospheric ozone and those for 50% ozone depletion, indicate about a 2.5-fold increase in dimer formation. If the action spectrum for DNA damage that results in skin cancer resembles that for dimer induction in skin, these results suggest that a 50% decrease in stratospheric ozone would increase the incidence of nonmelanoma skin cancers among white males in Seattle, Washington, by 7.5- to 8-fold, to a higher incidence than is presently seen in the corresponding population of Albuquerque, New Mexico

  10. Construction of a single/multiple wavelength RZ optical pulse source at 40 GHz by use of wavelength conversion in a high-nonlinearity DSF-NOLM

    DEFF Research Database (Denmark)

    Yu, Jianjun; Yujun, Qian; Jeppesen, Palle

    2001-01-01

    A single or multiple wavelength RZ optical pulse source at 40 GHz is successfully obtained by using wavelength conversion in a nonlinear optical loop mirror consisting of high nonlinearity-dispersion shifted fiber.......A single or multiple wavelength RZ optical pulse source at 40 GHz is successfully obtained by using wavelength conversion in a nonlinear optical loop mirror consisting of high nonlinearity-dispersion shifted fiber....

  11. Measurement and modeling of low-wavelength losses in silica fibers and their impact at communication Wavelengths

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Grüner-Nielsen, Lars; Rottwitt, Karsten

    2009-01-01

    Using the cutback technique, the attenuation of four different silica step-index fibers is measured in the very wide wavelength range of 190-1700 nm. The measured spectra are deconvolved into components describing Rayleigh scattering, infrared losses, Urbach edge, anomalous loss, and different...

  12. Is Alcohol Use Disorder Identification Test (AUDIT or its shorter versions more useful to identify risky drinkers in a Chinese population? A diagnostic study.

    Directory of Open Access Journals (Sweden)

    Benjamin H K Yip

    Full Text Available To examine the diagnostic performance of shorter versions of Alcohol Use Disorder Identification Test (AUDIT, including Alcohol Consumption (AUDIT-C, in identifying risky drinkers in primary care settings using conventional performance measures, supplemented by decision curve analysis and reclassification table.A cross-sectional study of adult males in general outpatient clinics in Hong Kong. The study included only patients who reported at least sometimes drinking alcoholic beverages. Timeline follow back alcohol consumption assessment method was used as the reference standard. A Chinese translated and validated 10-item AUDIT (Ch-AUDIT was used as a screening tool of risky drinking.Of the participants, 21.7% were classified as risky drinkers. AUDIT-C has the best overall performance among the shorter versions of Ch-AUDIT. The AUC of AUDIT-C was comparable to Ch-AUDIT (0.898 vs 0.901, p-value = 0.959. Decision curve analysis revealed that when the threshold probability ranged from 15-30%, the AUDIT-C had a higher net-benefit than all other screens. AUDIT-C improved the reclassification of risky drinking when compared to Ch-AUDIT (net reclassification improvement = 0.167. The optimal cut-off of AUDIT-C was at ≥5.Given the rising levels of alcohol consumption in the Chinese regions, this Chinese translated 3-item instrument provides convenient and time-efficient risky drinking screening and may become an increasingly useful tool.

  13. On very-large-scale motions (VLSMs) and long-wavelength patterns in turbine wakes

    Science.gov (United States)

    Önder, Asim; Meyers, Johan

    2017-11-01

    It is now widely accepted that very-large-scale motions (VLSMs) are a prominent feature of thermally-neutral atmospheric boundary layers (ABL). Up to date, the influence of these very long active motions on wind-energy harvesting is not sufficiently explored. This work is an effort in this direction. We perform large-eddy simulation of a turbine row operating under neutral conditions. The ABL data is produced separately in a very long domain of 240 δ . VLSMs are isolated from smaller-scale ABL and wake motions using a spectral cutoff at streamwise wavelength λx = 3.125 δ . Reynolds-averaging of low-pass filtered fields shows that the interaction of VLSMs and turbines produce very-long-wavelength motions in the wake region, which contain about 20 % of the Reynolds-shear stress, and 30 % of the streamwise kinetic energy. A conditional analysis of filtered fields further reveals that these long-wavelength wakes are produced by modification of very long velocity streaks in ABL. In particular, the turbine row acts as a sharp boundary between low and high velocity streaks, and accompanying roller structures remain relatively unaffected. This reorganization creates a two-way flux towards the wake region, which elucidates the side-way domination in turbulent transport. The authors acknowledg funding from ERC Grant No 306471.

  14. Wavelength prediction of laser incident on amorphous silicon detector by neural network

    International Nuclear Information System (INIS)

    Esmaeili Sani, V.; Moussavi-Zarandi, A.; Kafaee, M.

    2011-01-01

    In this paper we present a method based on artificial neural networks (ANN) and the use of only one amorphous semiconductor detector to predict the wavelength of incident laser. Amorphous semiconductors and especially amorphous hydrogenated silicon, a-Si:H, are now widely used in many electronic devices, such as solar cells, many types of position sensitive detectors and X-ray imagers for medical applications. In order to study the electrical properties and detection characteristics of thin films of a-Si:H, n-i-p structures have been simulated by SILVACO software. The basic electronic properties of most of the materials used are known, but device modeling depends on a large number of parameters that are not all well known. In addition, the relationship between the shape of the induced anode current and the wavelength of the incident laser leads to complicated calculations. Soft data-based computational methods can model multidimensional non-linear processes and represent the complex input-output relation between the form of the output signal and the wavelength of incident laser.

  15. Wavelength prediction of laser incident on amorphous silicon detector by neural network

    Energy Technology Data Exchange (ETDEWEB)

    Esmaeili Sani, V., E-mail: vaheed_esmaeely80@yahoo.com [Amirkabir University of Technology, Faculty of Physics, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of); Moussavi-Zarandi, A.; Kafaee, M. [Amirkabir University of Technology, Faculty of Physics, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of)

    2011-10-21

    In this paper we present a method based on artificial neural networks (ANN) and the use of only one amorphous semiconductor detector to predict the wavelength of incident laser. Amorphous semiconductors and especially amorphous hydrogenated silicon, a-Si:H, are now widely used in many electronic devices, such as solar cells, many types of position sensitive detectors and X-ray imagers for medical applications. In order to study the electrical properties and detection characteristics of thin films of a-Si:H, n-i-p structures have been simulated by SILVACO software. The basic electronic properties of most of the materials used are known, but device modeling depends on a large number of parameters that are not all well known. In addition, the relationship between the shape of the induced anode current and the wavelength of the incident laser leads to complicated calculations. Soft data-based computational methods can model multidimensional non-linear processes and represent the complex input-output relation between the form of the output signal and the wavelength of incident laser.

  16. Effect of light with different wavelengths on Nostoc flagelliforme cells in liquid culture.

    Science.gov (United States)

    Dai, Yu-Jie; Li, Jing; Wei, Shu-Mei; Chen, Nan; Xiao, Yu-Peng; Tan, Zhi-Lei; Jia, Shi-Ru; Yuan, Nan-Nan; Tan, Ning; Song, Yi-Jie

    2013-04-01

    The effects of lights with different wavelengths on the growth and the yield of extracellular polysaccharides of Nostoc flagelliforme cells were investigated in a liquid cultivation. N. flagelliforme cells were cultured for 16 days in 500 ml conical flasks containing BG11 culture medium under 27 micromol·m-2·s-1 of light intensity and 25 degrees C on a rotary shaker (140 rpm). The chlorophyll a, phycocyanin, allophycocyanin, and phycoerythrin contents in N. flagelliforme cells under the lights of different wavelengths were also measured. It was found that the cell biomass and the yield of polysaccharide changed with different wavelengths of light. The biomass and the yield of extracellular polysaccharides under the red or violet light were higher than those under other light colors. Chlorophyll a, phycocyanin, and allophycocyanin are the main pigments in N. flagelliforme cells. The results showed that N. flagelliforme, like other cyanobacteria, has the ability of adjusting the contents and relative ratio of its pigments with the light quality. As a conclusion, N. flagelliforme cells favor red and violet lights and perform the complementary chromatic adaptation ability to acclimate to the changes of the light quality in the environment.

  17. 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.

  18. Smartphone snapshot mapping of skin chromophores under triple-wavelength laser illumination

    Science.gov (United States)

    Spigulis, Janis; Oshina, Ilze; Berzina, Anna; Bykov, Alexander

    2017-09-01

    Chromophore distribution maps are useful tools for skin malformation severity assessment and for monitoring of skin recovery after burns, surgeries, and other interactions. The chromophore maps can be obtained by processing several spectral images of skin, e.g., captured by hyperspectral or multispectral cameras during seconds or even minutes. To avoid motion artifacts and simplify the procedure, a single-snapshot technique for mapping melanin, oxyhemoglobin, and deoxyhemoglobin of in-vivo skin by a smartphone under simultaneous three-wavelength (448-532-659 nm) laser illumination is proposed and examined. Three monochromatic spectral images related to the illumination wavelengths were extracted from the smartphone camera RGB image data set with respect to crosstalk between the RGB detection bands. Spectral images were further processed accordingly to Beer's law in a three chromophore approximation. Photon absorption path lengths in skin at the exploited wavelengths were estimated by means of Monte Carlo simulations. The technique was validated clinically on three kinds of skin lesions: nevi, hemangiomas, and seborrheic keratosis. Design of the developed add-on laser illumination system, image-processing details, and the results of clinical measurements are presented and discussed.

  19. Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar.

    Science.gov (United States)

    Li, Zhan; Jupp, David L B; Strahler, Alan H; Schaaf, Crystal B; Howe, Glenn; Hewawasam, Kuravi; Douglas, Ewan S; Chakrabarti, Supriya; Cook, Timothy A; Paynter, Ian; Saenz, Edward J; Schaefer, Michael

    2016-03-02

    Radiometric calibration of the Dual-Wavelength Echidna(®) Lidar (DWEL), a full-waveform terrestrial laser scanner with two simultaneously-pulsing infrared lasers at 1064 nm and 1548 nm, provides accurate dual-wavelength apparent reflectance (ρ(app)), a physically-defined value that is related to the radiative and structural characteristics of scanned targets and independent of range and instrument optics and electronics. The errors of ρ(app) are 8.1% for 1064 nm and 6.4% for 1548 nm. A sensitivity analysis shows that ρ(app) error is dominated by range errors at near ranges, but by lidar intensity errors at far ranges. Our semi-empirical model for radiometric calibration combines a generalized logistic function to explicitly model telescopic effects due to defocusing of return signals at near range with a negative exponential function to model the fall-off of return intensity with range. Accurate values of ρ(app) from the radiometric calibration improve the quantification of vegetation structure, facilitate the comparison and coupling of lidar datasets from different instruments, campaigns or wavelengths and advance the utilization of bi- and multi-spectral information added to 3D scans by novel spectral lidars.

  20. Multi-wavelength investigations on feedback of massive star formation

    Science.gov (United States)

    Yuan, Jinghua

    2014-05-01

    In the course of massive star formation, outflows, ionizing radiation and intense stellar winds could heavily affect their adjacent environs and natal clouds. There are several outstanding open questions related to these processes: i) whether they can drive turbulence in molecular clouds; ii) whether they are able to trigger star formation; iii) whether they can destroy natal clouds to terminate star formation at low efficiencies. This thesis investigates feedback in different stages of massive star formation. Influence of such feedback to the ambient medium has been revealed. A new type of millimeter methanol maser is detected for the first time. An uncommon bipolar outflow prominent in the mid-infrared is discovered. And features of triggered star formation are found on the border of an infrared bubble and in the surroundings of a Herbig Be star. Extended green objects (EGOs) are massive outflow candidates showing prominent shocked features in the mid-infrared. We have carried out a high resolution study of the EGO G22.04+0.22 (hereafter, G22) based on archived SMA data. Continuum and molecular lines at 1.3 mm reveal that G22 is still at a hot molecular core stage. A very young multi-polar outflow system is detected, which is interacting with the adjacent dense gas. Anomalous emission features from CH3OH (8,-1,8 - 7,0,7) and CH3OH (4,2,2 - 3,1,2) are proven to be millimeter masers. It is the first time that maser emission of CH3OH (8,-1,8 - 7,0,7) at 218.440 GHz is detected in a massive star-forming region. Bipolar outflows have been revealed and investigated almost always in the microwave or radio domain. It's sort of rare that hourglass-shaped morphology be discovered in the mid-infrared. Based on GLIMPSE data, we have discovered a bipolar object resembling an hourglass at 8.0 um. It is found to be associated with IRAS 18114-1825. Analysis based on fitted SED, optical spectroscopy, and infrared color indices suggests IRAS 18114-1825 is an uncommon bipolar

  1. Rigorous Progress on Algorithms Based Routing and Wavelength Assignment in Trans-Egypt Network (TEGYNET) Management

    OpenAIRE

    Abd El–Naser A. Mohammed; Ahmed Nabih Zaki Rashed; Osama S. Fragallah; Mohamed G. El-Abyad

    2013-01-01

    In simple wavelength-division multiplexed (WDM) networks, a connection must be established along a route using a common wavelength on all of the links along the route. The introduction of wavelength converters into WDM cross connects increases the hardware cost and complexity. Given a set of connection requests, the routing and wavelength assignment problem involves finding a route (routing) and assigning a wavelength to each request. This paper has presented the WDM technology is being exten...

  2. THE EFFICIENCY AND WAVELENGTH DEPENDENCE OF NEAR-INFRARED INTERSTELLAR POLARIZATION TOWARD THE GALACTIC CENTER

    Energy Technology Data Exchange (ETDEWEB)

    Hatano, Hirofumi; Kurita, Mikio; Kanai, Saori; Sato, Shuji [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Nishiyama, Shogo; Nakajima, Yasushi; Tamura, Motohide; Kandori, Ryo [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8858 (Japan); Nagata, Tetsuya; Yoshikawa, Tatsuhito [Department of Astronomy, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Kato, Daisuke [Department of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sato, Yaeko; Suenaga, Takuya, E-mail: hattan@z.phys.nagoya-u.ac.jp, E-mail: shogo.nishiyama@nao.ac.jp [Department of Astronomical Sciences, Graduate University for Advanced Studies (Sokendai), Mitaka, Tokyo 181-8858 (Japan)

    2013-04-15

    Near-infrared polarimetric imaging observations toward the Galactic center (GC) have been carried out to examine the efficiency and wavelength dependence of interstellar polarization. A total area of about 5.7 deg{sup 2} is covered in the J, H, and K{sub S} bands. We examined the polarization efficiency, defined as the ratio of the degree of polarization to color excess. The interstellar medium between the GC and us shows a polarization efficiency lower than that in the Galactic disk by a factor of three. Moreover we investigated the spatial variation of the polarization efficiency by comparing it with that of the color excess, degree of polarization, and position angle. The spatial variations of color excess and degree of polarization depend on the Galactic latitude, while the polarization efficiency varies independently of the Galactic structure. Position angles are nearly parallel to the Galactic plane, indicating a longitudinal magnetic field configuration between the GC and us. The polarization efficiency anticorrelates with dispersions of position angles. The low polarization efficiency and its spatial variation can be explained by the differences in the magnetic field directions along the line of sight. From the lower polarization efficiency, we suggest a higher strength of a random component relative to a uniform component of the magnetic field between the GC and us. We also derived the ratios of degree of polarization p{sub H} /p{sub J} = 0.581 {+-} 0.004 and p{sub K{sub S}}/p{sub H} = 0.620 {+-} 0.002. The power-law indices of the wavelength dependence of polarization are {beta}{sub JH} = 2.08 {+-} 0.02 and {beta}{sub HK{sub S}} = 1.76 {+-} 0.01. Therefore, the wavelength dependence of interstellar polarization exhibits flattening toward longer wavelengths in the range of 1.25-2.14 {mu}m. The flattening would be caused by aligned large-size dust grains.

  3. SPP-assisted sub-wavelength reflection-type THz imaging with THz time-domain spectrometer

    Science.gov (United States)

    Lai, Senfeng; Wu, Yanghui; Wu, Wen; Gu, Wenhua

    2017-08-01

    THz imaging has become a hot research topic in recent years, thanks to its merits of non-contact, strong penetration, immunity to hostile environments, and nondestructive detection. However, its spatial resolution is limited by the relatively long wavelength, so the location and measurement precision can only reach the level of the imaging wavelength, which has become a severe limitation of THz imaging. A simple way using surface plasmonic polartons (SPPs) to improve the location and measurement precision of THz by one order of magnitude was proposed in this manuscript, which can realize subwavelength THz imaging.

  4. Influence of ns-laser wavelength in laser-induced breakdown spectroscopy for discrimination of painting techniques

    Science.gov (United States)

    Bai, Xueshi; Syvilay, Delphine; Wilkie-Chancellier, Nicolas; Texier, Annick; Martinez, Loic; Serfaty, Stéphane; Martos-Levif, Dominique; Detalle, Vincent

    2017-08-01

    The influence of ns-laser wavelength to discriminate ancient painting techniques such as are fresco, casein, animal glue, egg yolk and oil was investigated in this work. This study was carried out with a single shot laser on samples covered by a layer made of a mixture of the cinnabar pigment and different binders. Three wavelengths based on Nd: YAG laser were investigated (1064, 532 and 266 nm). The plasma is controlled at the same electron temperature after an adjustment of pulse energy for these three wavelengths on a fresco sample without organic binder. This approach allows to eliminate the effects of laser pulse energy and the material laser absorption. Afterwards, the emission spectra were compared to separate different techniques. The organic binding media has been separated based on the relative emission intensity of the present CN or C2 rovibrational emissions. In order to test the capability of separating or identifying, the chemometric approach (PCA) was applied to the different matrix. The different solutions in term of wavelength range to optimise the identification was investigated. We focused on the evaluation for the laser wavelength to insure a better separation. The different capacity was interpreted by differentiating the binders by the altered interaction mechanisms between the laser photon and the binders. Also, the electron temperature in the plasma was estimated, which provided the evidences to our findings.

  5. Dual wavelength Mode-Locking of InAs/InP quantum dot laser diodes at 1.5µm

    NARCIS (Netherlands)

    Tahvili, M.S.; Heck, M.J.R.; Nötzel, R.; Smit, M.K.; Bente, E.A.J.M.

    2011-01-01

    We report on stable dual-wavelength mode-locking of 3.1GHz and 10GHz two-section InAs/InP(100) quantum dot laser diodes. Evaluation of relative time delay between different spectral components indicates opposite sign of chirp over the two spectral lobes

  6. Multi-Wavelength Polarimetry of Isolated Neutron Stars

    Directory of Open Access Journals (Sweden)

    Roberto P. Mignani

    2018-03-01

    Full Text Available Isolated neutron stars are known to be endowed with extreme magnetic fields, whose maximum intensity ranges from 10 12 – 10 15 G, which permeates their magnetospheres. Their surrounding environment is also strongly magnetized, especially in the compact nebulae powered by the relativistic wind from young neutron stars. The radiation from isolated neutron stars and their surrounding nebulae is, thus, supposed to bring a strong polarization signature. Measuring the neutron star polarization brings important information about the properties of their magnetosphere and of their highly magnetized environment. Being the most numerous class of isolated neutron stars, polarization measurements have been traditionally carried out for radio pulsars, hence in the radio band. In this review, I summarize multi-wavelength linear polarization measurements obtained at wavelengths other than radio both for pulsars and other types of isolated neutron stars and outline future perspectives with the upcoming observing facilities.

  7. Cavity-enhanced resonant tunneling photodetector at telecommunication wavelengths

    International Nuclear Information System (INIS)

    Pfenning, Andreas; Hartmann, Fabian; Langer, Fabian; Höfling, Sven; Kamp, Martin; Worschech, Lukas

    2014-01-01

    An AlGaAs/GaAs double barrier resonant tunneling diode (RTD) with a nearby lattice-matched GaInNAs absorption layer was integrated into an optical cavity consisting of five and seven GaAs/AlAs layers to demonstrate cavity enhanced photodetection at the telecommunication wavelength 1.3 μm. The samples were grown by molecular beam epitaxy and RTD-mesas with ring-shaped contacts were fabricated. Electrical and optical properties were investigated at room temperature. The detector shows maximum photocurrent for the optical resonance at a wavelength of 1.29 μm. At resonance a high sensitivity of 3.1×10 4 A/W and a response up to several pA per photon at room temperature were found

  8. Automated dual-wavelength spectrophotometer optimized for phytochrome assay

    International Nuclear Information System (INIS)

    Pratt, L.H.; Wampler, J.E.; Rich, E.S. Jr.

    1985-01-01

    A microcomputer-controlled dual-wavelength spectrophotometer suitable for automated phytochrome assay is described. The optomechanical unit provides for sequential irradiation of the sample by the two measuring wavelengths with intervening dark intervals and for actinic irradiation to interconvert phytochrome between its two forms. Photomultiplier current is amplified, converted to a digital value and transferred into the computer using a custom-designed IEEE-488 bus interface. The microcomputer calculates mathematically both absorbance and absorbance difference values with dynamic correction for photomultiplier dark current. In addition, the computer controls the operating parameters of the spectrophotometer via a separate interface. These parameters include control of the durations of measuring and actinic irradiation intervals and their sequence. 14 references, 4 figures

  9. Wavelength shifting reflector foils for liquid Ar scintillation light

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Manuel [Physik Institut, Universitaet Zuerich (Switzerland); Collaboration: GERDA-Collaboration

    2013-07-01

    Liquid argon is used as a scintillator in several present and upcoming experiments. In Gerda it is used as a coolant, shielding and will be instrumented to become an active veto in Phase II. Its scintillation light has a wavelength of 128 nm, that gets absorbed by quartz. In order to measure the light using photo multiplier tubes (PMT) for cryogenic temperatures which have a quartz window, it is converted to longer wavelength by coated reflector foils. The conversion efficiency and stability of several such coatings was optimized using VM2000 and Tetratex separately as reflector foils. The efficiency has been measured in a liquid Ar set up build especially for this purpose. It employs a 3'' low radioactivity PMT of type R11065-10 from Hamamatsu, the favorite photo sensor candidate to be used in Gerda.

  10. High accuracy wavelength calibration for a scanning visible spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Scotti, Filippo; Bell, Ronald E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2010-10-15

    Spectroscopic applications for plasma velocity measurements often require wavelength accuracies {<=}0.2 A. An automated calibration, which is stable over time and environmental conditions without the need to recalibrate after each grating movement, was developed for a scanning spectrometer to achieve high wavelength accuracy over the visible spectrum. This method fits all relevant spectrometer parameters using multiple calibration spectra. With a stepping-motor controlled sine drive, an accuracy of {approx}0.25 A has been demonstrated. With the addition of a high resolution (0.075 arc sec) optical encoder on the grating stage, greater precision ({approx}0.005 A) is possible, allowing absolute velocity measurements within {approx}0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

  11. Microscopic single-crystal refractometry as a function of wavelength

    International Nuclear Information System (INIS)

    DeLoach, L.D.

    1994-01-01

    The refractive indices of crystal fragments 50--200 μm in size can be measured for light wavelengths between 365 and 1100 nm with a spindle-stage refractometer. Established methods from optical crystallograpy are used to orient a crystal on the microscope spindle stage and then to match its refractive index to an immersion fluid. The refractive index of the fluid for the wavelength of light and matching temperature is determined by comparison of a reference crystal on a second spindle axis with the fluid under the match conditions. Investigations of new nonlinear-optical crystals admirably demonstrate the advantages of measuring the refractive index to ± 0.0004 in small single crystals

  12. Dual-Wavelength Sensitized Photopolymer for Holographic Data Storage

    Science.gov (United States)

    Tao, Shiquan; Zhao, Yuxia; Wan, Yuhong; Zhai, Qianli; Liu, Pengfei; Wang, Dayong; Wu, Feipeng

    2010-08-01

    Novel photopolymers for holographic storage were investigated by combining acrylate monomers and/or vinyl monomers as recording media and liquid epoxy resins plus an amine harder as binder. In order to improve the holographic performances of the material at blue-green wavelength band two novel dyes were used as sensitizer. The methods of evaluating the holographic performances of the material, including the shrinkage and noise characteristics, are described in detail. Preliminary experiments show that samples with optimized composite have good holographic performances, and it is possible to record dual-wavelength hologram simultaneously in this photopolymer by sharing the same optical system, thus the storage density and data rate can be doubly increased.

  13. Light Wavelength Correlation on the Effect of Hair Growth

    International Nuclear Information System (INIS)

    Wan Saffiey Wan Abdullah

    2010-01-01

    The use of laser light as a bio stimulator at certain wavelength is a new development in laser photonics and become an acceptable tool in medical therapy. It based on low power and low energy laser light. The effect of biological cells behaviour to low power laser light stimulates various studies in many areas such as for medical and cosmetic applications. This paper discusses some results of low power laser light that is used for stimulating the hair growth of skinned mouse by using an optically expanded low power laser light. The study indicates that the red light laser provide a significant growth of mouse hair with exposure duration of two hours daily for 24 consecutive days. Apart from that the green laser light is also used in this study; however result shows no significant influence to the growth of mouse hair in this light wavelength. (author)

  14. Comparison of different wavelength pump sources for Tm subnanosecond amplifier

    Science.gov (United States)

    Cserteg, Andras; Guillemet, Sébastien; Hernandez, Yves; Giannone, Domenico

    2012-06-01

    We report here a comparison of different pumping wavelengths for short pulse Thulium fibre amplifiers. We compare the results in terms of efficiency and required fibre length. As we operate the laser in the sub-nanosecond regime, the fibre length is a critical parameter regarding non linear effects. With 793 nm clad-pumping, a 4 m long active fibre was necessary, leading to strong spectral deformation through Self Phase Modulation (SPM). Core-pumping scheme was then more in-depth investigated with several wavelengths tested. Good results with Erbium and Raman shifted pumping sources were obtained, with very short fibre length, aiming to reach a few micro-joules per pulse without (or with limited) SPM.

  15. Approaches for a quantum memory at telecommunication wavelengths

    International Nuclear Information System (INIS)

    Lauritzen, Bjoern; Minar, Jiri; Riedmatten, Hugues de; Afzelius, Mikael; Gisin, Nicolas

    2011-01-01

    We report experimental storage and retrieval of weak coherent states of light at telecommunication wavelengths using erbium ions doped into a solid. We use two photon-echo-based quantum storage protocols. The first one is based on controlled reversible inhomogeneous broadening (CRIB). It allows the retrieval of the light on demand by controlling the collective atomic coherence with an external electric field, via the linear Stark effect. We study how atoms in the excited state affect the signal-to-noise ratio of the CRIB memory. Additionally we show how CRIB can be used to modify the temporal width of the retrieved light pulse. The second protocol is based on atomic frequency combs. Using this protocol we verify that the reversible mapping is phase preserving by performing an interference experiment with a local oscillator. These measurements are enabling steps toward solid-state quantum memories at telecommunication wavelengths. We also give an outlook on possible improvements.

  16. System and Method for Multi-Wavelength Optical Signal Detection

    Science.gov (United States)

    McGlone, Thomas D. (Inventor)

    2017-01-01

    The system and method for multi-wavelength optical signal detection enables the detection of optical signal levels significantly below those processed at the discrete circuit level by the use of mixed-signal processing methods implemented with integrated circuit technologies. The present invention is configured to detect and process small signals, which enables the reduction of the optical power required to stimulate detection networks, and lowers the required laser power to make specific measurements. The present invention provides an adaptation of active pixel networks combined with mixed-signal processing methods to provide an integer representation of the received signal as an output. The present invention also provides multi-wavelength laser detection circuits for use in various systems, such as a differential absorption light detection and ranging system.

  17. Optogalvanic wavelength calibration for laser monitoring of reactive atmospheric species

    Science.gov (United States)

    Webster, C. R.

    1982-01-01

    Laser-based techniques have been successfully employed for monitoring atmospheric species of importance to stratospheric ozone chemistry or tropospheric air quality control. When spectroscopic methods using tunable lasers are used, a simultaneously recorded reference spectrum is required for wavelength calibration. For stable species this is readily achieved by incorporating into the sensing instrument a reference cell containing the species to be monitored. However, when the species of interest is short-lived, this approach is unsuitable. It is proposed that wavelength calibration for short-lived species may be achieved by generating the species of interest in an electrical or RF discharge and using optogalvanic detection as a simple, sensitive, and reliable means of recording calibration spectra. The wide applicability of this method is emphasized. Ultraviolet, visible, or infrared lasers, either CW or pulsed, may be used in aircraft, balloon, or shuttle experiments for sensing atoms, molecules, radicals, or ions.

  18. Linear programming phase unwrapping for dual-wavelength digital holography.

    Science.gov (United States)

    Wang, Zhaomin; Jiao, Jiannan; Qu, Weijuan; Yang, Fang; Li, Hongru; Tian, Ailing; Asundi, Anand

    2017-01-20

    A linear programming phase unwrapping method in dual-wavelength digital holography is proposed and verified experimentally. The proposed method uses the square of height difference as a convergence standard and theoretically gives the boundary condition in a searching process. A simulation was performed by unwrapping step structures at different levels of Gaussian noise. As a result, our method is capable of recovering the discontinuities accurately. It is robust and straightforward. In the experiment, a microelectromechanical systems sample and a cylindrical lens were measured separately. The testing results were in good agreement with true values. Moreover, the proposed method is applicable not only in digital holography but also in other dual-wavelength interferometric techniques.

  19. Observation of Rayleigh - Taylor growth to short wavelengths on Nike

    International Nuclear Information System (INIS)

    Pawley, C.J.; Bodner, S.E.; Dahlburg, J.P.; Obenschain, S.P.; Schmitt, A.J.; Sethian, J.D.; Sullivan, C.A.; Gardner, J.H.; Aglitskiy, Y.; Chan, Y.; Lehecka, T.

    1999-01-01

    The uniform and smooth focal profile of the Nike KrF laser [S. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to ablatively accelerate 40 μm thick polystyrene planar targets with pulse shaping to minimize shock heating of the compressed material. The foils had imposed small-amplitude sinusoidal wave perturbations of 60, 30, 20, and 12.5 μm wavelength. The shortest wavelength is near the ablative stabilization cutoff for Rayleigh - Taylor growth. Modification of the saturated wave structure due to random laser imprint was observed. Excellent agreement was found between the two-dimensional simulations and experimental data for most cases where the laser imprint was not dominant. copyright 1999 American Institute of Physics

  20. Dual-wavelength laser transmission photoscanner for breast cancer detection

    International Nuclear Information System (INIS)

    Kaneko, M.; He, P.; Tanaka, H.; Takahashi, M.; Takai, M.; Baba, K.; Yamashita, Y.; Ohta, K.

    1989-01-01

    This paper reports on the prototype of a laser transmission photoscanner (LTPS) constructed and used for the detection of breast cancer and compared with x-ray mammography. LTPS has been improved to enable spectroanalysis and application in breast cancer screening. The new type is introduced. In order to obtain higher sensitivity, the output of lasers was increased in intensity. The signal integration time was increased 10-fold, and the width of the detector area was doubled. The gated operation of the detector enables the good throughput. Simultaneous scanning in the dual wavelengths of 630 and 830 nm makes it possible to differentiate hemoglobin (Hb) and oxyhemoglobin (HbO 2 ) in spectroanalysis by means of Lambert--Beer's law. Clinical application of dual-wavelength LTPS shows good correlation with pathology

  1. MULTI-WAVELENGTH AFTERGLOWS OF FAST RADIO BURSTS

    International Nuclear Information System (INIS)

    Yi, Shuang-Xi; Gao, He; Zhang, Bing

    2014-01-01

    The physical origin of fast radio bursts (FRBs) is unknown. Detecting electromagnetic counterparts to FRBs in other wavelengths is essential to measure their distances and to determine their physical origin. Assuming that at least some of them are of cosmological origin, we calculate their afterglow light curves in multiple wavelengths (X-rays, optical, and radio) by assuming a range of total kinetic energies and redshifts. We focus on forward shock emission, but also consider the possibility that some of the FRBs might have bright reverse shock emission. In general, FRB afterglows are too faint to be detected by current detectors. Only if an FRB has a very low radiative efficiency in radio (hence, a very large kinetic energy), and when it is close enough to observe can its afterglow be detected in the optical and radio bands. We discuss observational strategies for detecting these faint afterglows using future telescopes such as Large Synoptic Survey Telescope and Expanded Very Large Array

  2. Multi-Wavelength Monitoring of GRS 1915+105

    Science.gov (United States)

    Bandyopadhyay, R.; Martini, P.; Gerard, E.; Charles, P. A.; Wagner, R. M.; Shrader, C.; Shahbaz, T.; Mirabel, I. F.

    1997-01-01

    Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here first results from a multi-wavelength campaign undertaken from July to September 1996. This study includes X-ray data from the RXTE All Sky Monitor and BATSE, two-frequency data from the Nancay radio telescope, and infrared photometry from the 1.8 m Perkins telescope at Lowell Observatory. The first long-term well-sampled IR light curve of GRS 1915+105 is presented herein and is consistent with the interpretation of this source as a long-period binary. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities.

  3. Laser-assisted decontamination—A wavelength dependent study

    Science.gov (United States)

    Nilaya, J. Padma; Raote, Pallavi; Kumar, Aniruddha; Biswas, Dhruba J.

    2008-09-01

    We present here the experimental results on cleaning of radioactive dielectric particulates, loosely deposited on stainless steel, by coherent light of 1064 nm wavelength and its three harmonics occurring at 532 nm, 355 nm and 266 nm, derived from an Nd-YAG laser. For the initial few exposures, the decontamination factor has been found to be highest when exposed to 1064 nm radiation. With increasing number of exposures, however, the radiation with reducing wavelength assumes a more important role as a cleaning agent. The observation of almost no cleaning with 1064 nm and much reduced cleaning with its harmonics when the contamination is deposited on a transparent substrate confirms the dominant role played by metal substrate towards expelling the loose particulates from its surface.

  4. The sub-wavelength imaging performance of disordered wire media

    International Nuclear Information System (INIS)

    Powell, David A.

    2008-01-01

    An analysis of the sub-wavelength imaging performance of disordered thin wire media is undertaken, in order to understand how its performance may be affected by manufacturing errors. The structure is found to be extremely robust to disorder which keeps the wires parallel. Variation in the orientation of the wires and their longitudinal position causes more significant degradation in the image quality, which is quantified numerically

  5. Dual wavelength operation in diode-end-pumped hybrid vanadate ...

    Indian Academy of Sciences (India)

    Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd3+-doped birefringent YVO4 and GdVO4 crystals is demon-strated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition ...

  6. Properties of Sub-wavelength Resonances in Metamaterial Cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Clausen, N.C.J.; Pedersen, R.R.

    2008-01-01

    The analytical solution for the canonical configuration with electric line source illumination of concentric metamaterial cylinders is employed to study the properties of the observed sub-wavelength resonances. The near- and far-field distributions, the frequency and geometry bandwidths, and the ......, and the line source impedance are investigated for varying electromagnetic and geometrical parameters. The results of this study are of importance for metamaterial-based miniaturization of antennas....

  7. Wavelength-independent all-fiber mode converters.

    Science.gov (United States)

    Lai, K; Leon-Saval, S G; Witkowska, A; Wadsworth, W J; Birks, T A

    2007-02-15

    We have used two different photonic crystal fiber (PCF) techniques to make all-fiber mode converters. An LP(01) to LP(11) mode converter was made by the ferrule technique on a drawing tower, and an LP(01) to LP(02) mode converter was made by controlled hole inflation of an existing PCF on a tapering rig. Both devices rely on adiabatic propagation rather than resonant coupling; so high extinction was achieved across a wide wavelength range.

  8. Free-space wavelength-multiplexed optical scanner demonstration.

    Science.gov (United States)

    Yaqoob, Zahid; Riza, Nabeel A

    2002-09-10

    Experimental demonstration of a no-moving-parts free-space wavelength-multiplexed optical scanner (W-MOS) is presented. With fast tunable lasers or optical filters and planar wavelength dispersive elements such as diffraction gratings, this microsecond-speed scanner enables large several-centimeter apertures for subdegree angular scans. The proposed W-MOS design incorporates a unique optical amplifier and variable optical attenuator combination that enables the calibration and modulation of the scanner response, leading to any desired scanned laser beam power shaping. The experimental setup uses a tunable laser centered at 1560 nm and a 600-grooves/mm blazed reflection grating to accomplish an angular scan of 12.92 degrees as the source is tuned over an 80-nm bandwidth. The values for calculated maximum optical beam divergance, required wavelength resolution, beam-pointing accuracy, and measured scanner insertion loss are 1.076 mrad, 0.172 nm, 0.06 mrad, and 4.88 dB, respectively.

  9. Long wavelength limit of evolution of nonlinear cosmological perturbations

    International Nuclear Information System (INIS)

    Hamazaki, Takashi

    2008-01-01

    In the general matter composition where the multiple scalar fields and the multiple perfect fluids coexist, in the leading order of the gradient expansion, we construct all of the solutions of the nonlinear evolutions of the locally homogeneous universe. From the momentum constraint, we derive the constraints which the solution constants of the locally homogeneous universe must satisfy. We construct the gauge invariant perturbation variables in the arbitrarily higher order nonlinear cosmological perturbation theory around the spatially flat Friedmann-Robertson-Walker universe. We construct the nonlinear long wavelength limit formula representing the long wavelength limit of the evolution of the nonlinear gauge invariant perturbation variables in terms of perturbations of the evolutions of the locally homogeneous universe. By using the long wavelength limit formula, we investigate the evolution of nonlinear cosmological perturbations in the universe dominated by the multiple slow rolling scalar fields with an arbitrary potential. The τ function and the N potential introduced in this paper make it possible to write the evolution of the multiple slow rolling scalar fields with an arbitrary interaction potential and the arbitrarily higher order nonlinear Bardeen parameter at the end of the slow rolling phase analytically. It is shown that the nonlinear parameters such as f NL and g NL are suppressed by the slow rolling expansion parameters.

  10. New preemptive scheduling for OBS networks considering cascaded wavelength conversion

    Science.gov (United States)

    Gao, Xingbo; Bassiouni, Mostafa A.; Li, Guifang

    2009-05-01

    In this paper we introduce a new preemptive scheduling technique for next generation optical burst-switched networks considering the impact of cascaded wavelength conversions. It has been shown that when optical bursts are transmitted all optically from source to destination, each wavelength conversion performed along the lightpath may cause certain signal-to-noise deterioration. If the distortion of the signal quality becomes significant enough, the receiver would not be able to recover the original data. Accordingly, subject to this practical impediment, we improve a recently proposed fair channel scheduling algorithm to deal with the fairness problem and aim at burst loss reduction simultaneously in optical burst switching. In our scheme, the dynamic priority associated with each burst is based on a constraint threshold and the number of already conducted wavelength conversions among other factors for this burst. When contention occurs, a new arriving superior burst may preempt another scheduled one according to their priorities. Extensive simulation results have shown that the proposed scheme further improves fairness and achieves burst loss reduction as well.

  11. Effective long wavelength scalar dynamics in de Sitter

    Energy Technology Data Exchange (ETDEWEB)

    Moss, Ian; Rigopoulos, Gerasimos, E-mail: ian.moss@newcastle.ac.uk, E-mail: gerasimos.rigopoulos@ncl.ac.uk [School of Mathematics and Statistics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU U.K. (United Kingdom)

    2017-05-01

    We discuss the effective infrared theory governing a light scalar's long wavelength dynamics in de Sitter spacetime. We show how the separation of scales around the physical curvature radius k / a ∼ H can be performed consistently with a window function and how short wavelengths can be integrated out in the Schwinger-Keldysh path integral formalism. At leading order, and for time scales Δ t >> H {sup −1}, this results in the well-known Starobinsky stochastic evolution. However, our approach allows for the computation of quantum UV corrections, generating an effective potential on which the stochastic dynamics takes place. The long wavelength stochastic dynamical equations are now second order in time, incorporating temporal scales Δ t ∼ H {sup −1} and resulting in a Kramers equation for the probability distribution—more precisely the Wigner function—in contrast to the more usual Fokker-Planck equation. This feature allows us to non-perturbatively evaluate, within the stochastic formalism, not only expectation values of field correlators, but also the stress-energy tensor of φ.

  12. Research with high-power short-wavelength lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Campbell, E.M.; Lindl, J.D.; Storm, E.

    1985-01-01

    Three important high-temperature, high-density experiments were conducted recently using the 10-TW, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. These experiments demonstrated successful solutions to problems that arose during previous experiments with long wavelength lasers (lambda greater than or equal to 1μm) in which inertial confinement fusion (ICF), x-ray laser, and other high-temperature physics concepts were being tested. The demonstrations were: (1) large-scale plasmas (typical dimensions of up to 1000 laser wavelengths) were produced in which potentially deleterious laser-plasma instabilities were collisionally damped. (2) Deuterium-tritium fuel was imploded to a density of 20 g/cm 3 and a pressure of 10 10 atm. (3) A 700-fold amplification of soft x rays by stimulated emission at 206 and 209 A (62 eV) from Se +24 ions was observed in a laser-generated plasma. Isoelectronic scaling to 155 A (87 eV) in Y +29 was also demonstrated

  13. Photoacoustic imaging at 1064nm wavelength with exogenous contrast agents

    Science.gov (United States)

    Upputuri, Paul Kumar; Jiang, Yuyan; Pu, Kanyi; Pramanik, Manojit

    2018-02-01

    Photoacoustic (PA) imaging is a promising imaging modality for both preclinical research and clinical practices. Laser wavelengths in the first near infrared window (NIR-I, 650-950 nm) have been widely used for photoacoustic imaging. As compared with NIR-I window, scattering of photons by biological tissues is largely reduced in the second NIR (NIR-II) window, leading to enhanced imaging fidelity. However, the lack of biocompatible NIR-II absorbing exogenous agents prevented the use of this window for in vivo imaging. In recent years, few studies have been reported on photoacoustic imaging in NIR-II window using exogenous contrast agents. In this work, we discuss the recent work on PA imaging using 1064 nm wavelength, the fundamental of Nd:YAG laser, as an excitation wavelength. The PA imaging at 1064 nm is advantageous because of the low and homogeneous signal from tissue background, enabling high contrast in PA imaging when NIR-II absorbing contrast agents are employed.

  14. Wavelength and ambient luminance dependence of laser eye dazzle.

    Science.gov (United States)

    Williamson, Craig A; McLin, Leon N; Rickman, J Michael; Manka, Michael A; Garcia, Paul V; Kinerk, Wesley T; Smith, Peter A

    2017-10-10

    A series of experiments has been conducted to quantify the effects of laser wavelength and ambient luminance on the severity of laser eye dazzle experienced by human subjects. Eight laser wavelengths in the visible spectrum were used (458-647 nm) across a wide range of ambient luminance conditions (0.1-10,000  cd·m -2 ). Subjects were exposed to laser irradiance levels up to 600  μW·cm -2 and were asked to recognize the orientation of optotypes at varying eccentricities up to 31.6 deg of visual angle from the laser axis. More than 40,000 data points were collected from 14 subjects (ages 23-64), and these were consolidated into a series of obscuration angles for comparison to a theoretical model of laser eye dazzle. Scaling functions were derived to allow the model to predict the effects of laser dazzle on vision more accurately by including the effects of ambient luminance and laser wavelength. The updated model provides an improved match to observed laser eye dazzle effects across the full range of conditions assessed. The resulting model will find use in a variety of laser safety applications, including the estimation of maximum dazzle exposure and nominal ocular dazzle distance values.

  15. Mid-wavelength infrared unipolar nBp superlattice photodetector

    Science.gov (United States)

    Kazemi, Alireza; Myers, Stephen; Taghipour, Zahra; Mathews, Sen; Schuler-Sandy, Ted; Lee, Seunghyun; Cowan, Vincent M.; Garduno, Eli; Steenbergen, Elizabeth; Morath, Christian; Ariyawansa, Gamini; Scheihing, John; Krishna, Sanjay

    2018-01-01

    We report a Mid-Wavelength Infrared (MWIR) barrier photodetector based on the InAs/GaSb/AlSb type-II superlattice (T2SL) material system. The nBp design consists of a single unipolar barrier (InAs/AlSb SL) placed between a 4 μm thick p-doped absorber (InAs/GaSb SL) and an n-type contact layer (InAs/GaSb SL). At 80 K, the device exhibited a 50% cut-off wavelength of 5 μm, was fully turned-ON at zero bias and the measured QE was 50% (front side illumination with no AR coating) at 4.5 μm with a dark current density of 4.7 × 10-6 A/cm2 at Vb = 50 mV. At 150 K and Vb = 50 mV, the 50% cut-off wavelength increased to 5.3 μm, and the QE was 54% at 4.5 μm with a dark current of 5.0 × 10-4 A/cm2.

  16. SPLASH-SXDF Multi-wavelength Photometric Catalog

    Science.gov (United States)

    Mehta, Vihang; Scarlata, Claudia; Capak, Peter; Davidzon, Iary; Faisst, Andreas; Hsieh, Bau Ching; Ilbert, Olivier; Jarvis, Matt; Laigle, Clotilde; Phillips, John; Silverman, John; Strauss, Michael A.; Tanaka, Masayuki; Bowler, Rebecca; Coupon, Jean; Foucaud, Sébastien; Hemmati, Shoubaneh; Masters, Daniel; McCracken, Henry Joy; Mobasher, Bahram; Ouchi, Masami; Shibuya, Takatoshi; Wang, Wei-Hao

    2018-04-01

    We present a multi-wavelength catalog in the Subaru/XMM-Newton Deep Field (SXDF) as part of the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH). We include the newly acquired optical data from the Hyper-Suprime-Cam Subaru Strategic Program, accompanied by IRAC coverage from the SPLASH survey. All available optical and near-infrared data is homogenized and resampled on a common astrometric reference frame. Source detection is done using a multi-wavelength detection image including the u-band to recover the bluest objects. We measure multi-wavelength photometry and compute photometric redshifts as well as physical properties for ∼1.17 million objects over ∼4.2 deg2, with ∼800,000 objects in the 2.4 deg2 HSC-Ultra-Deep coverage. Using the available spectroscopic redshifts from various surveys over the range of 0 fraction of 3.2%. The SPLASH-SXDF catalog is a valuable, publicly available resource, perfectly suited for studying galaxies in the early universe and tracing their evolution through cosmic time.

  17. Fabrication of sub-wavelength photonic structures by nanoimprint lithography

    Energy Technology Data Exchange (ETDEWEB)

    Kontio, J.

    2013-11-01

    Nanoimprint lithography (NIL) is a novel but already a mature lithography technique. In this thesis it is applied to the fabrication of nanophotonic devices using its main advantage: the fast production of sub-micron features in high volume in a cost-effective way. In this thesis, fabrication methods for conical metal structures for plasmonic applications and sub-wavelength grating based broad-band mirrors are presented. Conical metal structures, nanocones, with plasmonic properties are interesting because they enable concentrating the energy of light in very tight spots resulting in very high local intensities of electromagnetic energy. The nanocone formation process is studied with several metals. Enhanced second harmonic generation using gold nanocones is presented. Bridged-nanocones are used to enhance Raman scattering from a dye solution. The sub-wavelength grating mirror is an interesting structure for photonics because it is very simple to fabricate and its reflectivity can be extended to the far infrared wavelength range. It also has polarization dependent properties which are used in this thesis to stabilize the output beam of infrared semiconductor disk laser. NIL is shown to be useful a technique in the fabrication of nanophotonic devices in the novel and rapidly growing field of plasmonics and also in more traditional, but still developing, semiconductor laser applications (orig.)

  18. High Numbers of Stromal Cancer-Associated Fibroblasts Are Associated With a Shorter Survival Time in Cats With Oral Squamous Cell Carcinoma.

    Science.gov (United States)

    Klobukowska, H J; Munday, J S

    2016-11-01

    Cancer-associated fibroblasts (CAFs) are fibroblastic cells that express α-smooth muscle actin and have been identified in the stroma of numerous epithelial tumors. The presence of CAFs within the tumor stroma has been associated with a poorer prognosis in some human cancers, including oral squamous cell carcinomas (SCCs). Cats frequently develop oral SCCs, and although these are generally highly aggressive neoplasms, there is currently a lack of prognostic markers for these tumors. The authors investigated the prognostic value of the presence of CAFs within the stroma of oral SCC biopsy specimens from 47 cats. In addition, several epidemiologic, clinical, and histologic variables were also assessed for prognostic significance. A CAF-positive stroma was identified in 35 of 47 SCCs (74.5%), and the median survival time (ST) of cats with CAF-positive SCCs (35 days) was significantly shorter than that of cats with CAF-negative SCCs (48.5 days) (P = .031). ST was also associated with the location of the primary tumor (P = .0018): the median ST for oropharyngeal SCCs (179 days) was significantly longer than for maxillary (43.5 days; P = .047), mandibular (42 days; P = .022), and sublingual SCCs (22.5 days; P = .0005). The median ST of sublingual SCCs was also shorter compared with maxillary SCCs (P = .0017). Furthermore, a significant association was identified between site and the presence of stromal CAFs (P = .025). On the basis of this retrospective study, evaluating the tumor stroma for CAFs in feline oral SCC biopsy specimens may be of potential prognostic value. © The Author(s) 2016.

  19. Self-produced Time Intervals Are Perceived as More Variable and/or Shorter Depending on Temporal Context in Subsecond and Suprasecond Ranges

    Directory of Open Access Journals (Sweden)

    Keita eMitani

    2016-06-01

    Full Text Available The processing of time intervals is fundamental for sensorimotor and cognitive functions. Perceptual and motor timing are often performed concurrently (e.g., playing a musical instrument. Although previous studies have shown the influence of body movements on time perception, how we perceive self-produced time intervals has remained unclear. Furthermore, it has been suggested that the timing mechanisms are distinct for the sub- and suprasecond ranges. Here, we compared perceptual performances for self-produced and passively presented time intervals in random contexts (i.e., multiple target intervals presented in a session across the sub- and suprasecond ranges (Experiment 1 and within the sub- (Experiment 2 and suprasecond (Experiment 3 ranges, and in a constant context (i.e., a single target interval presented in a session in the sub- and suprasecond ranges (Experiment 4. We show that self-produced time intervals were perceived as shorter and more variable across the sub- and suprasecond ranges and within the suprasecond range but not within the subsecond range in a random context. In a constant context, the self-produced time intervals were perceived as more variable in the suprasecond range but not in the subsecond range. The impairing effects indicate that motor timing interferes with perceptual timing. The dependence of impairment on temporal contexts suggests multiple timing mechanisms for the subsecond and suprasecond ranges. In addition, violation of the scalar property (i.e., a constant variability to target interval ratio was observed between the sub- and suprasecond ranges. The violation was clearer for motor timing than for perceptual timing. This suggests that the multiple timing mechanisms for the sub- and suprasecond ranges overlap more for perception than for motor. Moreover, the central tendency effect (i.e., where shorter base intervals are overestimated and longer base intervals are underestimated disappeared with subsecond

  20. Effect of Group Exercising and Adjusting the Brace at Shorter Intervals on Cobb Angle and Quality of Life of Patients with Idiopathic Scoliosis

    Directory of Open Access Journals (Sweden)

    Zahra Hedayati

    2016-01-01

    Full Text Available Objective: Bracing along with exercising is the most effective protocol in patients with idiopathic scoliosis which have Cobb angles of 25 to 45 degrees. However, since the psychological aspects of scoliosis treatment may affect the quality of life, and the exact time for adjusting the pads of Milwaukee brace is unknown; Therefore the aim of this study was evaluating the effect of exercising in a group, with adjusting the brace in shorter intervals, in compare to routine protocol, in the treatment of idiopathic scoliosis. Matterials & Methods: Thirty-four patients with idiopathic scoliosis which had Cobb angles of 50 to 15 degrees were included in this study and were divided into experimental and control groups. The patients of two groups participated in an eleven-week treatment program, differ between the two groups. Quality of life scores of both groups were evaluated before and after intervention using SRS-22 questionnaire, as well as scoliosis angles before and after the intervention according to the primary and secondary radiographic X-rays. Results: Statistical analysis was performed using Paired T-Test in each group, and Independent T-Test between the two groups before and after treatment. The severity of scoliosis curvature and satisfaction domain of the experimental group was reduced significantly in compared with the control group, after intervention (P=0.04. Moreover in the case of  the quality of life in patients with Cobb angles less than 30 degrees, compared with patients with Cobb angles greater than 31 degrees, in the domains of self-image, satisfaction, and total score, the difference was significant (P<0.05. Conclusion: Adjusting the brace at shorter intervals along with exercising as a group, during the eleven weeks of treatment, has increased satisfaction and reduced the scoliosis Cobb angles of patients.

  1. Mutation induction by and mutational interaction between monochromatic wavelength radiations in the near-ultraviolet and visible ranges

    International Nuclear Information System (INIS)

    Tyrrell, R.M.

    1980-01-01

    The induction of mutations (reversion to tryptophan independence) by various UV (254, 313, 334 and 365 nm) and visible (405 and 434 nm) wavelengths was measured in exponential phase populations of Escherichia coli B/r thy trp and B/r thy trp uvr A by assay of irradiated populations on semi-enriched media. No mutations were induced in the repair proficient strain at wavelengths longer than 313 nm. Mutations were induced to the excisionless strain at wavelengths as long as 405 nm but less than expected from the known amount of DNA damage induced. Irradiation at the long wavelenths (434, 405, 365 and 334 nm) suppressed the appearance of 254- or 313 nm-induced mutations in the repair competent strain but not in the excision deficient strain. The relative dose-requirement for mutation suppression was related to the relative efficiency of these wavelengths in inducing growth delay. These results suggest that the growth delay induced by near-UV and visible wavelenghts allows more time for the 'error-free' excision repair process to act on the potentially mutagenic lesions induced by 254- and 313-nm radiations, thereby reducing the mutation frequency observed in the repair-proficient strain. The level of near-UV mutation induced in the excision deficient strain is lower than expected from the DNA damage known to be induced. It is possible that near-UV radiation induces a class of lethal lesions that are not susceptible to error-prone repair. (author)

  2. Analysis of Saturn's Thermal Emission at 2.2-cm Wavelength: Spatial Distribution of Ammonia Vapor

    Science.gov (United States)

    Laraia, A. L.; Ingersoll, A. P.; Janssen, Michael A.; Gulkis, Samuel; Oyafuso, Fabiano A.; Allison, Michael D.

    2013-01-01

    This work focuses on determining the latitudinal structure of ammonia vapor in Saturn's cloud layer near 1.5 bars using the brightness temperature maps derived from the Cassini RADAR (Elachi et al., 2004) instrument, which works in a passive mode to measure thermal emission from Saturn at 2.2-cm wavelength. We perform an analysis of five brightness temperature maps that span epochs from 2005 to 2011, which are presented in a companion paper by Janssen et al. (2013a, this issue). The brightness temperature maps are representative of the spatial distribution of ammonia vapor, since ammonia gas is the only effective opacity source in Saturn's atmosphere at 2.2-cm wavelength. Relatively high brightness temperatures indicate relatively low ammonia relative humidity (RH), and vice versa. We compare the observed brightness temperatures to brightness temperatures computed using the Juno atmospheric microwave radiative transfer (JAMRT) program which includes both the means to calculate a tropospheric atmosphere model for Saturn and the means to carry out radiative transfer calculations at microwave frequencies. The reference atmosphere to which we compare has a 3x solar deep mixing ratio of ammonia (we use 1.352x10(exp -4) for the solar mixing ratio of ammonia vapor relative to H2; see Atreya, 2010) and is fully saturated above its cloud base. The maps are comprised of residual brightness temperatures-observed brightness temperature minus the model brightness temperature of the saturated atmosphere.

  3. Comprehensive Wavelengths, Energy Levels, and Hyperfine Structure Parameters of Singly-Ionized Iron-Group Elements

    Science.gov (United States)

    Nave, Gillian

    We propose to measure wavelengths, energy levels, and hyperfine structure parameters of Ni II, Mn II, Sc II and other singly-ionized iron-group elements, covering the wavelength range 80 nm to 5500 nm. We shall use archival data from spectrometers at NIST and Kitt Peak National Observatory for spectra above 140 nm. Additional experimental observations will be taken if needed using Fourier transform spectrometers at NIST. Spectra will be taken using our normal incidence grating spectrograph to provide better sensitivity than the FT spectra and to extend the wavelength range down to 80 nm. We aim to produce a comprehensive description of the spectra of all singly-ionized iron- group elements. The wavelength uncertainty of the strong lines will be better than 1 part in 10^7. For most singly-ionized iron-group elements available laboratory data have uncertainties an order of magnitude larger than astronomical observations over wide spectra ranges. Some of these laboratory measurements date back to the 1960's. Since then, Fourier transform spectroscopy has made significant progress in improving the accuracy and quantity of data in the UV-vis-IR region, but high quality Fourier transform spectra are still needed for Mn II, Ni II and Sc II. Fourier transform spectroscopy has low sensitivity in the VUV region and is limited to wavelengths above 140 nm. Spectra measured with high-resolution grating spectrographs are needed in this region in order to obtain laboratory data of comparable quality to the STIS and COS spectrographs on the Hubble Space Telescope. Currently, such data exist only for Fe II and Cr II. Lines of Sc II, V II, and Mn II show hyperfine structure, but hyperfine structure parameters have been measured for relatively few lines of these elements. Significant errors can occur if hyperfine structure is neglected when abundances are determined from stellar spectra. Measurements of hyperfine structure parameters will be made using Fourier transform spectroscopy

  4. Sub-half-wavelength atom localization via phase control of a pair of bichromatic fields

    International Nuclear Information System (INIS)

    Xu Jun; Hu Xiangming

    2007-01-01

    We propose a scheme of atom localization based on the interaction of the atom in the Λ configuration with a strong bichromatic coupling field and a weak bichromatic probe field with equal frequency difference. One of the bichromatic coupling components is a standing-wave field, which imposes position information on the Rabi frequency. By varying the difference between the relative phases of the two bichromatic fields, the atom is localized in either of the two half-wavelength regions with 50% probability provided the population in the upper state is detected

  5. Scaling of laser-plasma interactions with laser wavelength and plasma size

    International Nuclear Information System (INIS)

    Max, C.E.; Campbell, E.M.; Mead, W.C.; Kruer, W.L.; Phillion, D.W.; Turner, R.E.; Lasinski, B.F.; Estabrook, K.G.

    1983-01-01

    Plasma size is an important parameter in wavelength-scaling experiments because it determines both the threshold and potential gain for a variety of laser-plasma instabilities. Most experiments to date have of necessity produced relatively small plasmas, due to laser energy and pulse-length limitations. We have discussed in detail three recent Livermore experiments which had large enough plasmas that some instability thresholds were exceeded or approached. Our evidence for Raman scatter, filamentation, and the two-plasmon decay instability needs to be confirmed in experiments which measure several instability signatures simultaneously, and which produce more quantitative information about the local density and temperature profiles than we have today

  6. Scaling of laser-plasma interactions with laser wavelength and plasma size

    Energy Technology Data Exchange (ETDEWEB)

    Max, C.E.; Campbell, E.M.; Mead, W.C.; Kruer, W.L.; Phillion, D.W.; Turner, R.E.; Lasinski, B.F.; Estabrook, K.G.

    1983-01-25

    Plasma size is an important parameter in wavelength-scaling experiments because it determines both the threshold and potential gain for a variety of laser-plasma instabilities. Most experiments to date have of necessity produced relatively small plasmas, due to laser energy and pulse-length limitations. We have discussed in detail three recent Livermore experiments which had large enough plasmas that some instability thresholds were exceeded or approached. Our evidence for Raman scatter, filamentation, and the two-plasmon decay instability needs to be confirmed in experiments which measure several instability signatures simultaneously, and which produce more quantitative information about the local density and temperature profiles than we have today.

  7. Surface photo-discoloration and degradation of dyed wood veneer exposed to different wavelengths of artificial light

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States); Shao, Lingmin [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Gao, Jianmin, E-mail: jmgao@bjfu.edu.cn [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Guo, Hongwu, E-mail: hwg5052@163.com [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Chen, Yao [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Cheng, Qingzheng; Via, Brian K. [Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States)

    2015-03-15

    Highlights: • Investigate the selective absorption of different wavelengths of UV–vis light by dyed wood chromophores. • Identify connection between light wavelengths and surface color changes and chemical structure degradation. • Study hypochromic effect based on surface reflectance and K/S absorption changes during UV–vis irradiation. - Abstract: The surface of dyed wood is prone to discoloration when exposed to light irradiation which significantly decreases its decorative effect and shortens its service life. The influence of light wavelength exposure to the surface of dyed wood was investigated to study the effect on discoloration and degradation. Acid Blue V and Acid Red GR dyed wood veneers were subjected to light exposure with different wavelengths from the UV to visible region (254–420 nm). Results showed that the surface discoloration of dyed wood was linearly related to lignin concentration and dyes degradation and the consequent transformation of chromophoric groups such as aromatic (C=C) and carbonyl (C=O) through methoxy reaction. The dyes, lignin and some active constituents were degraded severely, even at short exposures. Acid Blue V dyed wood exhibited greater discoloration than the Acid Red GR treatment. The reflectance and K/S absorption curve showed a hypochromic effect on the dyed wood surface. The dyes and wood chemical structure played a complex and combined role on the selective absorption of different wavelengths of light. The color change rate was apparent with 254 nm exposure in the initial stages, but a greater discoloration rate occurred on the samples irradiated at 313 and 340 nm than at 254 and 420 nm with the time prolonged. The degradation rate and degree of discoloration correlated well with the light energy and wavelength.

  8. Comparison of different Aethalometer correction schemes and a reference multi-wavelength absorption technique for ambient aerosol data

    Directory of Open Access Journals (Sweden)

    J. Saturno

    2017-08-01

    Full Text Available Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA, which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June–September 2014. The mean absorption coefficient (at 637 nm during this period was 1.8 ± 2.1 Mm−1, with a maximum of 15.9 Mm−1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption Ångström exponent (åABS retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct åABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the åABS retrieved from offline MWAA measurements.

  9. Immersion lithography defectivity analysis at DUV inspection wavelength

    Science.gov (United States)

    Golan, E.; Meshulach, D.; Raccah, N.; Yeo, J. Ho.; Dassa, O.; Brandl, S.; Schwarz, C.; Pierson, B.; Montgomery, W.

    2007-03-01

    Significant effort has been directed in recent years towards the realization of immersion lithography at 193nm wavelength. Immersion lithography is likely a key enabling technology for the production of critical layers for 45nm and 32nm design rule (DR) devices. In spite of the significant progress in immersion lithography technology, there remain several key technology issues, with a critical issue of immersion lithography process induced defects. The benefits of the optical resolution and depth of focus, made possible by immersion lithography, are well understood. Yet, these benefits cannot come at the expense of increased defect counts and decreased production yield. Understanding the impact of the immersion lithography process parameters on wafer defects formation and defect counts, together with the ability to monitor, control and minimize the defect counts down to acceptable levels is imperative for successful introduction of immersion lithography for production of advanced DR's. In this report, we present experimental results of immersion lithography defectivity analysis focused on topcoat layer thickness parameters and resist bake temperatures. Wafers were exposed on the 1150i-α-immersion scanner and 1200B Scanner (ASML), defect inspection was performed using a DUV inspection tool (UVision TM, Applied Materials). Higher sensitivity was demonstrated at DUV through detection of small defects not detected at the visible wavelength, indicating on the potential high sensitivity benefits of DUV inspection for this layer. The analysis indicates that certain types of defects are associated with different immersion process parameters. This type of analysis at DUV wavelengths would enable the optimization of immersion lithography processes, thus enabling the qualification of immersion processes for volume production.

  10. EFFECTS OF LIGHT WAVELENGTHS AND COHERENCE ON BASIDIOSPORES GERMINATION

    Directory of Open Access Journals (Sweden)

    Natalia Poyedinok

    2015-02-01

    Full Text Available The effects of light wavelengths and coherence on basidiospore germination of Agaricus bisporus, Flammulina velutipes, Ganoderma applanatum, Ganoderma lucidum, Hericium erinaceus, Lentinus edodes and Pleurotus ostreatus have been studied. Short-term low-intensity irradiation by coherent (laser light wavelength 488.0 nm and 632.8 nm at doses 45 and 230 mJ/cm2 has significantly increased the number of germinated basidiospores. It has established that there are differences in the photosensitivity not only between species but also between strains. Spores irradiation by 514.5 nm light has been either neutral or inhibitory. A comparative analysis of basidiospores sensitivity to laser and LED light has also been conducted. To stimulate germination of basidiospores and growth of monokaryons the most suitable solution was to use red coherent and incoherent light of 632.8 nm and 660,0 nm for A. bisporus, G. applanatum and P. ostreatus, red and blue coherent light of 632.8 nm and 488,0 nm for F. velutipes, and both red and blue laser and LED light G. lucidum and H. erinaceus and for L. edodes. No essential difference of a continuous wave mode and intermittent mode light effect at the same doses and wavelength on spore germination were revealed. Light influence has reduced germination time and formation of aerial mycelium on agar medium as compared to the original value and increased the growth rate of monosporous isolates. Characterization of basidiospores photosensitivity and development of environmentally friendly stimulating methods of their germination is important for creating highly effective technologies of mushrooms selection and cultivation.

  11. Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

    Science.gov (United States)

    Rodger, Andrew; Labrosse, Nicolas

    2017-09-01

    Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter/submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using the densities of electrons, hydrogen, and helium obtained from a radiative transfer code under non-local thermodynamic equilibrium (non-LTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 - 9.6 mm), however, we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 - 3.6 mm (Band 3) and 1.1 - 1.4 mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.

  12. The fabrication of millimeter-wavelength accelerating structures

    International Nuclear Information System (INIS)

    Chou, P.J.; Bowden, G.B.; Copeland, M.R.

    1996-11-01

    There is a growing interest in the development of high gradient (≥ 1 GeV/m) accelerating structures. The need for high gradient acceleration based on current microwave technology requires the structures to be operated in the millimeter wavelength. Fabrication of accelerating structures at millimeter scale with sub-micron tolerances poses great challenges. The accelerating structures impose strict requirements on surface smoothness and finish to suppress field emission and multipactor effects. Various fabrication techniques based on conventional machining and micromachining have been evaluated and tested. These will be discussed and measurement results presented

  13. Long wavelength limit of the current convective instability

    International Nuclear Information System (INIS)

    Huba, J.D.

    1984-01-01

    A linear theory is presented of the current convective instability in the long wavelength limit, i.e., kL >ω) and inertial (ν/sub i/n>>ω) limits where ω is the wave frequency and ν/sub i/n is the ion-neutral collision frequency. It is shown that the growth rate scales as k in the collisional limit and as k/sup 2/3/ in the inertial limit. The analytical solutions are compared to exact numerical solutions, and very good agreement is found. Applications to the auroral ionosphere are discussed

  14. Multi-Wavelength Interferometric Observations of YSO Disks

    Science.gov (United States)

    Ragland, Sam; Akeson, R.; Armandroff, T.; Colavita, M.; Cotton, W.; Danchi, W.; Hillenbrand, L.; Millan-Gabet, R.; Ridgway, S. T.; Traub, W.; Wizinowich, P.

    2010-01-01

    We initiated a multi-color interferometric study of YSO disks in the K, L and N bands using the Keck Interferometer. The initial results on two Herbig Ae/Be stars will be presented. Our observations are sensitive to the radial distribution of temperature in the inner region of the YSO disks. The geometric models show that the apparent size increases linearly with wavelength, suggesting that the disk is extended with a temperature gradient. We will discuss our results in conjunction with the previous measurements of these targets.

  15. Short-wavelength magnetic recording new methods and analyses

    CERN Document Server

    Ruigrok, JJM

    2013-01-01

    Short-wavelength magnetic recording presents a series of practical solutions to a wide range of problems in the field of magnetic recording. It features many new and original results, all derived from fundamental principles as a result of up-to-date research.A special section is devoted to the playback process, including the calculations of head efficiency and head impedance, derived from new theorems.Features include:A simple and fast method for measuring efficiency; a simple method for the accurate separation of the read and write behaviour of magnetic heads; a new concept - the bandpass hea

  16. Transmission of electromagnetic waves through sub-wavelength channels

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Luo, Yu; Mortensen, Asger

    2010-01-01

    We propose a method of tunneling electromagnetic (EM) waves through a channel with sub-wavelength cross section. By filling the channel with high-ε isotropic material and implementing two matching layers with uniaxial metamterial substrates, the guided waves can go through the narrow channel...... without being cut off, as if it has just passed through the original empty waveguide. Both the magnitude and phase information of the EM fields can be effectively restored after passing this channel, regardless of the polarization of the incoming wave. The performance of this subwavelength channel, which...

  17. Silicon nitride photonics: from visible to mid-infrared wavelengths

    Science.gov (United States)

    Micó, Gloria; Bru, Luis A.; Pastor, Daniel; Doménech, David; Fernández, Juan; Sánchez, Ana; Cirera, Josep M.; Domínguez, Carlos; Muñoz, Pascual

    2018-02-01

    Silicon nitride has received a lot of attention during the last ten years, for applications such as bio-photonics, tele/datacom, optical signal processing and sensing. In this paper, firstly an updated review of the state of the art of silicon nitride photonics integration platforms will be provided. Secondly, our developments on a moderate confinement Si3N4 platform in the near-infrared will be presented. Finally, our steps towards establishing a Si3N4 based platform for broadband operation spanning from visible to mid-infrared wavelengths will be introduced.

  18. Experimental tests of induced spatial incoherence using short laser wavelength

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Grun, J.; Herbst, M.J.

    1986-01-01

    The authors have developed a laser beam smoothing technique called induced spatial incoherence (ISI), which can produce the highly uniform focal profiles required for direct-drive laser fusion. Uniform well-controlled focal profiles are required to obtain the highly symmetric pellet implosions needed for high-energy gain. In recent experiments, the authors' tested the effects of ISI on high-power laser-target interaction. With short laser wavelength, the coupling physics dramatically improved over that obtained with an ordinary laser beam

  19. Modeling the DBR laser used as wavelength conversion device

    DEFF Research Database (Denmark)

    Braagaard, Carsten; Mikkelsen, Benny; Durhuus, Terji

    1994-01-01

    In this paper, a novel and efficient way to model the dynamic field in optical DBR-type semiconductor devices is presented. The model accounts for the longitudinal carrier, photon, and refractive index distribution. Furthermore, the model handles both active and passive sections that may include...... gratings. Thus, simulations of components containing, e.g., gain sections, absorptive sections, phase sections, and gratings, placed arbitrarily along the longitudinal direction of the cavity, are possible. Here, the model has been used for studying the DBR laser as a wavelength converter. Particularly...

  20. Tunable Optical Tweezers for Wavelength-dependent Measurements

    Science.gov (United States)

    2012-04-23

    have been studied in an optical levitation scheme over short laser wavelength ranges20 and for dye-loaded di- electric particles.21 In the first case...M. Block, IEEE J. Sel. Top. Quantum Electron. 2, 1066 (1996). 7K. Dholakia, W. M. Lee, L. Paterson, M. P. MacDonald, I. Andreev, P. Mthunzi, C. T. A...Brown, R. F. Marchington, and A. C. Riches, IEEE J. Sel. Top. Quantum Electron. 13, 1646 (2007). 8K. Dholakia, M. P. MacDonald, P. Zemanek, and T

  1. Reflective optical imaging system for extreme ultraviolet wavelengths

    Science.gov (United States)

    Viswanathan, V.K.; Newnam, B.E.

    1993-05-18

    A projection reflection optical system has two mirrors in a coaxial, four reflection configuration to reproduce the image of an object. The mirrors have spherical reflection surfaces to provide a very high resolution of object feature wavelengths less than 200 [mu]m, and preferably less than 100 [mu]m. An image resolution of features less than 0.05-0.1 [mu]m, is obtained over a large area field; i.e., 25.4 mm [times] 25.4 mm, with a distortion less than 0.1 of the resolution over the image field.

  2. Student Performance in Measuring Distance with Wavelengths in Various Settings

    Science.gov (United States)

    White, Gary

    2015-04-01

    When physics students are asked to measure the distance between two fixed locations using a pre-defined wavelength as a ruler, there is a surprising failure rate, at least partially due to the fact that the ``ruler'' to be used is not fixed in length (see ``Is a Simple Measurement Task a Roadblock to Student Understanding of Wave Phenomena?,'' by and references therein). I will show some data from introductory classes (algebra- and calculus-based) that replicate this result, and also show some interesting features when comparing a setting involving slinkies with a setting involving surface waves on water.

  3. Hot-plasma decoupling condition for long-wavelength modes

    International Nuclear Information System (INIS)

    Berk, H.L.; Van Dam, J.W.; Spong, D.

    1982-10-01

    The stability of layer modes is analyzed for z-pinch and bumpy cylinder models. These modes are long wavelength across the layer and flute-like along the field line. The stability condition can be expressed in terms of the ratio of hot to core plasma density. It is shown that to achieve conditions close to the Nelson, Lee-Van Dam core beta limit, one needs a considerably smaller hot to core plasma density than is required to achieve stability at zero core beta

  4. Characteristics of Smith-Purcell radiation in millimeter wavelength region

    International Nuclear Information System (INIS)

    Naumenko, G A; Potylitsyn, A P; Sukhikh, L G; Shevelev, M V; Popov, Yu; Karataev, P; Bleko, V

    2016-01-01

    Investigations of the Smith-Purcell radiation (SPR) were began with non-relativistic electron beams with some unexpected experimental results. Further the experimental investigations were performed with relativistic electron beams for application to beam diagnostics. Large discrepancy between different theoretical models significantly increases the role of experimental studies of this phenomenon. In this report we present some problems and features of experimental investigations of SPR in millimeter wavelength region. The problems of prewave zone and coherent effects are considered. The shadowing effect, focusing of radiation using a parabolic SPR target and effect of inclination of target strips were investigated with moderately relativistic electron beam. (paper)

  5. Wavelength variation of a standing wave along a vertical spring

    Science.gov (United States)

    Welsch, Dylan; Baker, Blane

    2018-03-01

    Hand-driven resonance can be observed readily in a number of mechanical systems including thin boards, rods, strings, and springs. In order to show such behavior in the vertical spring pictured in Fig. 1, a section of spring is grasped at a location about one meter from its free end and driven by small, circular motions of the hand. At driving frequencies of a few hertz, a dramatic standing wave is generated. One of the fascinating features of this particular standing wave is that its wavelength varies along the length of the spring.

  6. Wavelength-independent fringe spacing in rainbows from falling neutrons

    International Nuclear Information System (INIS)

    Berry, M.V.

    1982-01-01

    For particles with speed upsilon and mass m emitted isotropically from a point source and falling under gravity g, the quantal probability density is dominated by a paraboloidal caustic decorated with paraboloidal interference fringes. Near the caustic, the fringes have a spacing independent of upsilon and hence of wavelength, given by ΔR=3.53897x(h 2 /m 2 g)sup(1/3) for the first two (brightest) fringes at the level of the source. For neutrons in the Earth's field, ΔR=0.02617mm. The effect might be difficult to detect. (author)

  7. Molecular transport network security using multi-wavelength optical spins.

    Science.gov (United States)

    Tunsiri, Surachai; Thammawongsa, Nopparat; Mitatha, Somsak; Yupapin, Preecha P

    2016-01-01

    Multi-wavelength generation system using an optical spin within the modified add-drop optical filter known as a PANDA ring resonator for molecular transport network security is proposed. By using the dark-bright soliton pair control, the optical capsules can be constructed and applied to securely transport the trapped molecules within the network. The advantage is that the dark and bright soliton pair (components) can securely propagate for long distance without electromagnetic interference. In operation, the optical intensity from PANDA ring resonator is fed into gold nano-antenna, where the surface plasmon oscillation between soliton pair and metallic waveguide is established.

  8. Tropospheric aerosol backscatter background mode at CO2 wavelengths

    Science.gov (United States)

    Rothermel, Jeffry; Bowdle, David A.; Menzies, Robert T.; Post, Madison J.; Vaughan, J. Michael

    1989-01-01

    A comparison is made between three climatologies of backscatter measurements in the troposphere and lower stratosphere at CO2 wavelengths. These were obtained from several locations using ground-based and airborne lidar systems. All three measurement sets show similar features, specifically, a high frequency of occurrence of low backscatter over a limited range of values in the middle and upper atmosphere (the 'background mode'). This background mode is important for the design and performance simulation of the prospective satellite sensors that rely on atmospheric aerosols as scattering targets.

  9. Stability of short wavelength tearing and twisting modes

    International Nuclear Information System (INIS)

    Waelbroeck, F.L.

    1998-01-01

    The stability and mutual interaction of tearing and twisting modes in a torus is governed by matrices that generalize the well-known Δ' stability index. The diagonal elements of these matrices determine the intrinsic stability of modes that reconnect the magnetic field at a single resonant surface. The off-diagonal elements indicate the strength of the coupling between the different modes. The author shows how the elements of these matrices can be evaluated, in the limit of short wavelength, from the free energy driving radially extended ballooning modes. The author applies the results by calculating the tearing and twisting Δ' for a model high-beta equilibrium with circular flux surfaces

  10. Spin-wave wavelength down-conversion at thickness steps

    Science.gov (United States)

    Stigloher, Johannes; Taniguchi, Takuya; Madami, Marco; Decker, Martin; Körner, Helmut S.; Moriyama, Takahiro; Gubbiotti, Gianluca; Ono, Teruo; Back, Christian H.

    2018-05-01

    We report a systematic experimental study on the refraction and reflection of magnetostatic spin-waves at a thickness step between two Permalloy films of different thickness. The transmitted spin-waves for the transition from a thick film to a thin film have a higher wave vector compared to the incoming waves. Consequently, such systems may find use as passive wavelength transformers in magnonic networks. We investigate the spin-wave transmission behavior by studying the influence of the external magnetic field, incident angle, and thickness ratio of the films using time-resolved scanning Kerr microscopy and micro-focused Brillouin light scattering.

  11. Arbitrarily high super-resolving phase measurements at telecommunication wavelengths

    International Nuclear Information System (INIS)

    Kothe, Christian; Bjoerk, Gunnar; Bourennane, Mohamed

    2010-01-01

    We present two experiments that achieve phase super-resolution at telecommunication wavelengths. One of the experiments is realized in the space domain and the other is realized in the time domain. Both experiments show high visibility and are performed with standard lasers and single-photon detectors. The first experiment uses six-photon coincidences, whereas the latter experiment needs no coincidence measurements, is easy to perform, and achieves, in principle, arbitrarily high phase super-resolution. Here, we demonstrate a 30-fold increase of the resolution. We stress that neither entanglement nor joint detection is needed in these experiments, which demonstrates that neither is necessary to achieve phase super-resolution.

  12. Do Dysphagic Patients with an Absent Pharyngeal Swallow Have a Shorter Survival than Dysphagic Patients with Pharyngeal Swallow? Prognostic Importance of a Therapeutic Videoradiographic Swallowing Study (TVSS)

    International Nuclear Information System (INIS)

    Buelow, M.; Olsson, R.; Ekberg, O.

    2005-01-01

    Purpose: To study survival in two groups of dysphagic patients - one group unable to elicit the pharyngeal stage of swallow (APS) and another group with pharyngeal swallow (WPS) - and to compare recommendations regarding nutrition and therapeutic strategies based on the therapeutic swallowing study. Material and Methods: In this retrospective study, the records of dysphagic patients who have undergone a therapeutic videoradiographic swallowing study (TVSS) were reviewed. Forty patients without pharyngeal swallow were matched for age and gender with 40 patients with pharyngeal swallow; altogether 80 patients were included in the study. Survival was registered at 3, 12, and 72 months after the TVSS. Results: In this study, the APS group had a significantly shorter survival time compared to the WPS group when followed-up at 12 months. In the APS group, most patients (37.5% (15/40)) died within the 3 months after TVSS. At 72 months, 62.5% (25/40) of the patients in the APS group had died. In the WPS group, 5% (2/40) had died within 3 months and 47.4% (19/40) after 12 months. At 72 months, 52.5% (21/40) of the patients in the WPS group had died. Regarding nutritional and therapeutic recommendations based on TVSS, 34/40 in the APS group were recommended no oral intake. Eighteen naso-gastric tubes were placed directly after TVSS. The therapeutic strategies recommended were head-positioning, thermal tactile stimulation, and tongue exercises (in 8 patients). In the WPS group, all patients were recommended oral intake. Diet modification was recommended in 29 patients. The therapeutic strategies recommended were head-positioning, thermal tactile stimulation, tongue exercises, supraglottic swallow, and effortful swallow (in 24 patients). Conclusion: Patients unable to elicit the pharyngeal stage of swallow had a shorter survival time than patients with pharyngeal swallow, probably due to a more severe underlying disease. Tube feeding was more frequent in the APS group. Fewer

  13. The prosurvival activity of ascites against TRAIL is associated with a shorter disease-free interval in patients with ovarian cancer

    Directory of Open Access Journals (Sweden)

    Lane Denis

    2010-01-01

    associated with shorter disease-free interval. Conclusions The prosurvival activity of ascites against TRAIL is associated with shorter disease-free interval, which may be explained, at least in part, by ascites-induced cisplatin/paclitaxel resistance. Our findings suggest that ascites may contain prosurvival factors that protect against TRAIL and chemotherapy and consequently affect disease progression.

  14. An algorithm and a Tool for Wavelength Allocation in OMS-SP Ring Architecture

    DEFF Research Database (Denmark)

    Riaz, Muhammad Tahir; Pedersen, Jens Myrup; Madsen, Ole Brun

    2006-01-01

    OMS-SP ring is one of the well known architectures in Wavelength Division Multiplexing based optical fiber networks. The architecture supports a restorable full mesh in an optical fiber ring using multiple light wavelengths. The paper presents an algorithm to allocate wavelengths in the OMS-SP ri...... architecture. A tool is also introduced which implements the algorithm and assigns wavelengths. The proposed algorithm uses fewer number of wavelengths than the classical allocation method. The algorithm is described and results are presented.......OMS-SP ring is one of the well known architectures in Wavelength Division Multiplexing based optical fiber networks. The architecture supports a restorable full mesh in an optical fiber ring using multiple light wavelengths. The paper presents an algorithm to allocate wavelengths in the OMS-SP ring...

  15. The wavelength frame multiplication chopper system for the ESS test beamline at the BER II reactor—A concept study of a fundamental ESS instrument principle

    International Nuclear Information System (INIS)

    Strobl, M.; Bulat, M.; Habicht, K.

    2013-01-01

    Contributing to the design update phase of the European Spallation Source ESS–scheduled to start operation in 2019–a test beamline is under construction at the BER II research reactor at Helmholtz Zentrum Berlin (HZB). This beamline offers experimental test capabilities of instrument concepts viable for the ESS. The experiments envisaged at this dedicated beamline comprise testing of components as well as of novel experimental approaches and methods taking advantage of the long pulse characteristic of the ESS source. Therefore the test beamline will be equipped with a sophisticated chopper system that provides the specific time structure of the ESS and enables variable wavelength resolutions via wavelength frame multiplication (WFM), a fundamental instrument concept beneficial for a number of instruments at ESS. We describe the unique chopper system developed for these purposes, which allows constant wavelength resolution for a wide wavelength band. Furthermore we discuss the implications for the conceptual design for related instrumentation at the ESS

  16. Optimization of top coupling grating for very long wavelength QWIP based on surface plasmon

    Science.gov (United States)

    Wang, Guodong; Shen, Junling; Liu, Xiaolian; Ni, Lu; Wang, Saili

    2017-09-01

    The relative coupling efficiency of two-dimensional (2D) grating based on surface plasmon for very long wavelength quantum well infrared detector is analyzed by using the three-dimensional finite-difference time domain (3D-FDTD) method algorithm. The relative coupling efficiency with respect to the grating parameters, such as grating pitch, duty ratio, and grating thickness, is analyzed. The calculated results show that the relative coupling efficiency would reach the largest value for the 14.5 μm incident infrared light when taking the grating pitch as 4.4 μm, the duty ratio as 0.325, and the grating thickness as 0.07 μm, respectively.

  17. Fully reconfigurable 2x2 optical cross-connect using tunable wavelength switching modules

    DEFF Research Database (Denmark)

    Liu, Fenghai; Zheng, Xueyan; Pedersen, Rune Johan Skullerud

    2001-01-01

    A modular tunable wavelength switching module is proposed and used to construct 2x2 fully reconfigurable optical cross-connects. Large size optical switch is avoided in the OXC and it is easy to upgrade to more wavelength channels.......A modular tunable wavelength switching module is proposed and used to construct 2x2 fully reconfigurable optical cross-connects. Large size optical switch is avoided in the OXC and it is easy to upgrade to more wavelength channels....

  18. Wavelength-Converter Saving Span Restoration in GMPLS Controlled WDM Optical Networks

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Buron, Jakob Due; Andriolli, N.

    2006-01-01

    We present two label preference schemes to reduce wavelength-conversion during restoration path setup in GMPLS controlled optical networks exploiting span restoration. The amount of required wavelength-conversions can be reduced up to 34 percent.......We present two label preference schemes to reduce wavelength-conversion during restoration path setup in GMPLS controlled optical networks exploiting span restoration. The amount of required wavelength-conversions can be reduced up to 34 percent....

  19. Wavelength selectivity of on-axis surface plasmon laser filters

    International Nuclear Information System (INIS)

    Harmer, S W; Townsend, P D

    2002-01-01

    Excitation of surface plasmons on a metal substrate, via the attenuated total reflection method can theoretically offer preferential absorption of light at one particular wavelength, whilst reflecting the nearby spectrum. Normally this 'filtering' action is limited to removal of p-polarized light, and the acceptance angle of such a filtering device is very narrow, which limits practical applications, such as separation of fundamental and laser harmonics. The possibility of avoiding this angular precision is explored by considering the complex permittivity of metal composites. By using a two or more layer structure, as opposed to a single metal substrate, the acceptance angle of the device can be broadened, by a factor of about 15 times. An example is discussed for separation of the fundamental and harmonics from a Nd : YAG laser. Variants of the structure allow the design of an in-line transmission filter for the various wavelengths with sufficient angular tolerance to include focusing lenses. Avoidance of laser ablation of the metal is discussed

  20. Implications of a wavelength dependent PSF for weak lensing measurements.

    Science.gov (United States)

    Eriksen, Martin; Hoekstra, Henk

    2018-05-01

    The convolution of galaxy images by the point-spread function (PSF) is the dominant source of bias for weak gravitational lensing studies, and an accurate estimate of the PSF is required to obtain unbiased shape measurements. The PSF estimate for a galaxy depends on its spectral energy distribution (SED), because the instrumental PSF is generally a function of the wavelength. In this paper we explore various approaches to determine the resulting `effective' PSF using broad-band data. Considering the Euclid mission as a reference, we find that standard SED template fitting methods result in biases that depend on source redshift, although this may be remedied if the algorithms can be optimised for this purpose. Using a machine-learning algorithm we show that, at least in principle, the required accuracy can be achieved with the current survey parameters. It is also possible to account for the correlations between photometric redshift and PSF estimates that arise from the use of the same photometry. We explore the impact of errors in photometric calibration, errors in the assumed wavelength dependence of the PSF model and limitations of the adopted template libraries. Our results indicate that the required accuracy for Euclid can be achieved using the data that are planned to determine photometric redshifts.

  1. Energy Levels, wavelengths and hyperfine structure measurements of Sc II

    Science.gov (United States)

    Hala, Fnu; Nave, Gillian

    2018-01-01

    Lines of singly ionized Scandium (Sc II) along with other Iron group elements have been observed [1] in the region surrounding the massive star Eta Carinae [2,3] called the strontium filament (SrF). The last extensive analysis of Sc II was the four-decade old work of Johansson & Litzen [4], using low-resolution grating spectroscopy. To update and extend the Sc II spectra, we have made observation of Sc/Ar, Sc/Ne and Sc/Ge/Ar hollow cathode emission spectrum on the NIST high resolution FT700 UV/Vis and 2 m UV/Vis/IR Fourier transform spectrometers (FTS). More than 850 Sc II lines have been measured in the wavelength range of 187 nm to 3.2 μm. connecting a total of 152 energy levels. The present work also focuses to resolve hyperfine structure (HFS) in Sc II lines. We aim to obtain accurate transition wavelengths, improved energy levels and HFS constants of Sc II. The latest results from work in progress will be presented.Reference[1] Hartman H, Gull T, Johansson S and Smith N 2004 Astron. Astrophys. 419 215[2] Smith N, Morse J A and Gull T R 2004 Astrophys. J. 605 405[3] Davidson K and Humphreys R M 1997 Annu. Rev. Astron. Astrophys. 35[4] Johansson S and Litzén U 1980 Phys. Scr. 22 49

  2. CBET Experiments with Wavelength Shifting at the Nike Laser

    Science.gov (United States)

    Weaver, James; McKenty, P.; Bates, J.; Myatt, J.; Shaw, J.; Obenschain, K.; Oh, J.; Kehne, D.; Obenschain, S.; Lehmberg, R. H.; Tsung, F.; Schmitt, A. J.; Serlin, V.

    2016-10-01

    Studies conducted at NRL during 2015 searched for cross-beam energy transport (CBET) in small-scale plastic targets with strong gradients in planar, cylindrical, and spherical geometries. The targets were irradiated by two widely separated beam arrays in a geometry similar to polar direct drive. Data from these shots will be presented that show a lack of a clear CBET signature even with wavelength shifting of one set of beams. This poster will discuss the next campaign being planned, in part, with modelling codes developed at LLE. The next experiments will use a target configuration optimized to create stronger SBS growth. The primary path under consideration is to increase scale lengths 5-10x over the previous study by using exploding foils or low density foams. In addition to simulations, the presentation will also discuss improvements to the diagnostic suite and laser operations; for example, a new set of etalons will be available for the next campaign that should double the range of wavelength shifting between the two beam arrays. Work supported by DoE/NNSA.

  3. Multi-client quantum key distribution using wavelength division multiplexing

    International Nuclear Information System (INIS)

    Grice, Warren P.; Bennink, Ryan S.; Earl, Dennis Duncan; Evans, Philip G.; Humble, Travis S.; Pooser, Raphael C.; Schaake, Jason; Williams, Brian P.

    2011-01-01

    Quantum Key Distribution (QKD) exploits the rules of quantum mechanics to generate and securely distribute a random sequence of bits to two spatially separated clients. Typically a QKD system can support only a single pair of clients at a time, and so a separate quantum link is required for every pair of users. We overcome this limitation with the design and characterization of a multi-client entangled-photon QKD system with the capacity for up to 100 clients simultaneously. The time-bin entangled QKD system includes a broadband down-conversion source with two unique features that enable the multi-user capability. First, the photons are emitted across a very large portion of the telecom spectrum. Second, and more importantly, the photons are strongly correlated in their energy degree of freedom. Using standard wavelength division multiplexing (WDM) hardware, the photons can be routed to different parties on a quantum communication network, while the strong spectral correlations ensure that each client is linked only to the client receiving the conjugate wavelength. In this way, a single down-conversion source can support dozens of channels simultaneously--and to the extent that the WDM hardware can send different spectral channels to different clients, the system can support multiple client pairings. We will describe the design and characterization of the down-conversion source, as well as the client stations, which must be tunable across the emission spectrum.

  4. Wavelength dependency in high power laser cutting and welding

    Science.gov (United States)

    Havrilla, David; Ziermann, Stephan; Holzer, Marco

    2012-03-01

    Laser cutting and welding have been around for more than 30 years. Within those three decades there has never been a greater variety of high power laser types and wavelengths to choose from than there is today. There are many considerations when choosing the right laser for any given application - capital investment, cost of ownership, footprint, serviceability, along with a myriad of other commercial & economic considerations. However, one of the most fundamental questions that must be asked and answered is this - "what type of laser is best suited for the application?". Manufacturers and users alike are realizing what, in retrospect, may seem obvious - there is no such thing as a universal laser. In many cases there is one laser type and wavelength that clearly provides the highest quality application results. This paper will examine the application fields of high power, high brightness 10.6 & 1 micron laser welding & cutting and will provide guidelines for selecting the laser that is best suited for the application. Processing speed & edge quality serve as key criteria for cutting. Whereas speed, seam quality & spatter ejection provide the paradigm for welding.

  5. Remote sub-wavelength focusing of ultrasonically activated Lorentz current

    Science.gov (United States)

    Rekhi, Angad S.; Arbabian, Amin

    2017-04-01

    We propose the use of a combination of ultrasonic and magnetic fields in conductive media for the creation of RF electrical current via the Lorentz force, in order to achieve current generation with extreme sub-wavelength resolution at large depth. We demonstrate the modeling, generation, and measurement of Lorentz current in a conductive solution and show that this current can be localized at a distance of 13 cm from the ultrasonic source to a region about three orders of magnitude smaller than the corresponding wavelength of electromagnetic waves at the same operation frequency. Our results exhibit greater depth, tighter localization, and closer agreement with prediction than previous work on the measurement of Lorentz current in a solution of homogeneous conductivity. The proposed method of RF current excitation overcomes the trade-off between focusing and propagation that is fundamental in the use of RF electromagnetic excitation alone and has the potential to improve localization and depth of operation for RF current-based biomedical applications.

  6. Patients with Duchenne muscular dystrophy are significantly shorter than those with Becker muscular dystrophy, with the higher incidence of short stature in Dp71 mutated subgroup.

    Science.gov (United States)

    Matsumoto, Masaaki; Awano, Hiroyuki; Lee, Tomoko; Takeshima, Yasuhiro; Matsuo, Masafumi; Iijima, Kazumoto

    2017-11-01

    Duchenne and Becker muscular dystrophy (DMD/BMD) are caused by mutations in the dystrophin gene and are characterized by severe and mild progressive muscle wasting, respectively. Short stature has been reported as a feature of DMD in the Western hemisphere, but not yet confirmed in Orientals. Height of young BMD has not been fully characterized. Here, height of ambulant and steroid naive Japanese 179 DMD and 42 BMD patients between 4 and 10 years of age was retrospectively examined using height standard deviation score (SDS). The mean height SDS of DMD was -1.08 SD that was significantly smaller than normal (p < 0.001), indicating short stature of Japanese DMD. Furthermore, the mean height SDS of BMD was -0.27 SD, suggesting shorter stature than normal. Remarkably, the mean height SDS of DMD was significantly smaller than that of BMD (p < 0.0001). In DMD higher incidence of short stature (height SDS < -2.5 SD) was observed in Dp71 subgroup having mutations in dystrophin exons 63-79 than others having mutations in exons 1-62 (27.8% vs. 7.5%, p = 0.017). These suggested that height is influenced by dystrophin in not only DMD but also BMD and that dystrophin Dp71 has a role in height regulation. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Aiming for a shorter rheumatoid arthritis MRI protocol: can contrast-enhanced MRI replace T2 for the detection of bone marrow oedema?

    Energy Technology Data Exchange (ETDEWEB)

    Stomp, Wouter; Bloem, Johan L.; Reijnierse, Monique [Leiden University Medical Center, Department of Radiology, P.O. Box 9600, Leiden (Netherlands); Krabben, Annemarie; Heijde, Desiree van der; Huizinga, Tom W.J.; Helm-van Mil, Annette H.M. van der [Leiden University Medical Center, Department of Rheumatology, P.O. Box 9600, Leiden (Netherlands)

    2014-10-15

    To determine whether T1 post-gadolinium chelate images (T1Gd) can replace T2-weighted images (T2) for evaluating bone marrow oedema (BME), thereby allowing a shorter magnetic resonance imaging (MRI) protocol in rheumatoid arthritis (RA). In 179 early arthritis patients and 43 advanced RA patients, wrist and metacarpophalangeal joints were examined on a 1.5-T extremity MRI system with a standard protocol (coronal T1, T2 fat-saturated and coronal and axial T1 fat-saturated after Gd). BME was scored according to OMERACT RAMRIS by two observers with and without T2 images available. Agreement was assessed using intraclass correlation coefficients (ICCs) for semi-quantitative scores and test characteristics with T2 images as reference. Agreement between scores based on T2 and T1Gd images was excellent ICC (0.80-0.99). At bone level, sensitivity and specificity of BME on T1Gd compared to T2 were high for both patient groups and both readers (all ≥80 %). T1Gd and T2 images are equally suitable for evaluating BME. Because contrast is usually administered to assess (teno)synovitis, a short MRI protocol of T1 and T1Gd is sufficient in RA. (orig.)

  8. Shorter Exciton Lifetimes via an External Heavy-Atom Effect: Alleviating the Effects of Bimolecular Processes in Organic Light-Emitting Diodes.

    Science.gov (United States)

    Einzinger, Markus; Zhu, Tianyu; de Silva, Piotr; Belger, Christian; Swager, Timothy M; Van Voorhis, Troy; Baldo, Marc A

    2017-10-01

    Multiexcited-state phenomena are believed to be the root cause of two exigent challenges in organic light-emitting diodes; namely, efficiency roll-off and degradation. The development of novel strategies to reduce exciton densities under heavy load is therefore highly desirable. Here, it is shown that triplet exciton lifetimes of thermally activated delayed-fluorescence-emitter molecules can be manipulated in the solid state by exploiting intermolecular interactions. The external heavy-atom effect of brominated host molecules leads to increased spin-orbit coupling, which in turn enhances intersystem crossing rates in the guest molecule. Wave function overlap between the host and the guest is confirmed by combined molecular dynamics and density functional theory calculations. Shorter triplet exciton lifetimes are observed, while high photoluminescence quantum yields and essentially unaltered emission spectra are maintained. A change in the intersystem crossing rate ratio due to increased dielectric constants leads to almost 50% lower triplet exciton densities in the emissive layer in the steady state and results in an improved onset of the photoluminescence quantum yield roll-off at high excitation densities. Efficient organic light-emitting diodes with better roll-off behavior based on these novel hosts are fabricated, demonstrating the suitability of this concept for real-world applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Aiming for a shorter rheumatoid arthritis MRI protocol: can contrast-enhanced MRI replace T2 for the detection of bone marrow oedema?

    International Nuclear Information System (INIS)

    Stomp, Wouter; Bloem, Johan L.; Reijnierse, Monique; Krabben, Annemarie; Heijde, Desiree van der; Huizinga, Tom W.J.; Helm-van Mil, Annette H.M. van der

    2014-01-01

    To determine whether T1 post-gadolinium chelate images (T1Gd) can replace T2-weighted images (T2) for evaluating bone marrow oedema (BME), thereby allowing a shorter magnetic resonance imaging (MRI) protocol in rheumatoid arthritis (RA). In 179 early arthritis patients and 43 advanced RA patients, wrist and metacarpophalangeal joints were examined on a 1.5-T extremity MRI system with a standard protocol (coronal T1, T2 fat-saturated and coronal and axial T1 fat-saturated after Gd). BME was scored according to OMERACT RAMRIS by two observers with and without T2 images available. Agreement was assessed using intraclass correlation coefficients (ICCs) for semi-quantitative scores and test characteristics with T2 images as reference. Agreement between scores based on T2 and T1Gd images was excellent ICC (0.80-0.99). At bone level, sensitivity and specificity of BME on T1Gd compared to T2 were high for both patient groups and both readers (all ≥80 %). T1Gd and T2 images are equally suitable for evaluating BME. Because contrast is usually administered to assess (teno)synovitis, a short MRI protocol of T1 and T1Gd is sufficient in RA. (orig.)

  10. Contrast-enhanced photoacoustic imaging with an optical wavelength of 1064 nm

    Science.gov (United States)

    Kim, Jeesu; Park, Sara; Park, Gyeong Bae; Choi, Wonseok; Jeong, Unyong; Kim, Chulhong

    2018-02-01

    Photoacoustic (PA) imaging is a biomedical imaging method that can provide both structural and functional information of living tissues beyond the optical diffusion limit by combining the concepts of conventional optical and ultrasound imaging methods. Although endogenous chromophores can be utilized to acquire PA images of biological tissues, exogenous contrast agents that absorb near-infrared (NIR) lights have been extensively explored to improve the contrast and penetration depth of PA images. Here, we demonstrate Bi2Se3 nanoplates, that strongly absorbs NIR lights, as a contrast agent for PA imaging. In particularly, the Bi2Se3 nanoplates produce relatively strong PA signals with an optical wavelength of 1064 nm, which has several advantages for deep tissue imaging including: (1) relatively low absorption by other intrinsic chromophores, (2) cost-effective light source using Nd:YAG laser, and (3) higher available energy than other NIR lights according to American National Standards Institute (ANSI) safety limit. We have investigated deep tissue imaging capability of the Bi2Se3 nanoplates by acquiring in vitro PA images of microtubes under chicken breast tissues. We have also acquired in vivo PA images of bladders, gastrointestinal tracts, and sentinel lymph nodes in mice after injection of the Bi2Se3 nanoplates to verify their applicability to a variety of biomedical research. The results show the promising potential of the Bi2Se3 nanoplates as a PA contrast agent for deep tissue imaging with an optical wavelength of 1064 nm.

  11. Deriving Quantitative Crystallographic Information from the Wavelength-Resolved Neutron Transmission Analysis Performed in Imaging Mode

    Directory of Open Access Journals (Sweden)

    Hirotaka Sato

    2017-12-01

    Full Text Available Current status of Bragg-edge/dip neutron transmission analysis/imaging methods is presented. The method can visualize real-space distributions of bulk crystallographic information in a crystalline material over a large area (~10 cm with high spatial resolution (~100 μm. Furthermore, by using suitable spectrum analysis methods for wavelength-dependent neutron transmission data, quantitative visualization of the crystallographic information can be achieved. For example, crystallographic texture imaging, crystallite size imaging and crystalline phase imaging with texture/extinction corrections are carried out by the Rietveld-type (wide wavelength bandwidth profile fitting analysis code, RITS (Rietveld Imaging of Transmission Spectra. By using the single Bragg-edge analysis mode of RITS, evaluations of crystal lattice plane spacing (d-spacing relating to macro-strain and d-spacing distribution’s FWHM (full width at half maximum relating to micro-strain can be achieved. Macro-strain tomography is performed by a new conceptual CT (computed tomography image reconstruction algorithm, the tensor CT method. Crystalline grains and their orientations are visualized by a fast determination method of grain orientation for Bragg-dip neutron transmission spectrum. In this paper, these imaging examples with the spectrum analysis methods and the reliabilities evaluated by optical/electron microscope and X-ray/neutron diffraction, are presented. In addition, the status at compact accelerator driven pulsed neutron sources is also presented.

  12. New types of 2×2 wavelength-switching blocks for optical cross-connects

    DEFF Research Database (Denmark)

    Liu, Fenghai; Zheng, Xueyan; Pedersen, Rune Johan Skullerud

    2001-01-01

    Two types of modular 2×2 wavelength-switching blocks are proposed in this letter. A 2×2 fixed wavelength-switching block can cross-connect two fixed channels between two fibers, and a 2×2 tunable wavelength-switching block can cross-connect any two channels between two fibers. These modular blocks...

  13. A MULTI-WAVELENGTH 3D MODEL OF BD+30°3639

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, M. J.; Kastner, Joel H. [Chester F. Carlson Center for Imaging Science, School of Physics and Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester NY 14623 (United States)

    2016-10-01

    We present a 3D multi-wavelength reconstruction of BD+30°3639, one of the best-studied planetary nebulae in the solar neighborhood. BD+30°3639, which hosts a [WR]-type central star, has been imaged at wavelength regimes that span the electromagnetic spectrum, from radio to X-rays. We have used the astrophysical modeling software SHAPE to construct a 3D morpho-kinematic model of BD+30°3639. This reconstruction represents the most complete 3D model of a PN to date from the standpoint of the incorporation of multi-wavelength data. Based on previously published kinematic data in optical emission lines and in lines of CO (radio) and H{sub 2} (near-IR), we were able to reconstruct BD+30's basic velocity components assuming a set of homologous velocity expansion laws combined with collimated flows along the major axis of the nebula. We confirm that the CO “bullets” in the PN lie along an axis that is slightly misaligned with respect to the major axis of the optical nebula, and that these bullets are likely responsible for the disrupted structures of the ionized and H{sub 2}-emitting shells within BD+30. Given the relative geometries and thus dynamical ages of BD+30's main structural components, it is furthermore possible that the same jets that ejected the CO bullets are responsible for the generation of the X-ray-emitting hot bubble within the PN. Comparison of alternative viewing geometries for our 3D reconstruction of BD+30°3639 with imagery of NGC 40 and NGC 6720 suggests a common evolutionary path for these nebulae.

  14. Differentiation of ocular fundus fluorophores by fluorescence lifetime imaging using multiple excitation and emission wavelengths

    Science.gov (United States)

    Hammer, M.; Schweitzer, D.; Schenke, S.; Becker, W.; Bergmann, A.

    2006-10-01

    Ocular fundus autofluorescence imaging has been introduced into clinical diagnostics recently. It is in use for the observation of the age pigment lipofuscin, a precursor of age - related macular degeneration (AMD). But other fluorophores may be of interest too: The redox pair FAD - FADH II provides information on the retinal energy metabolism, advanced glycation end products (AGE) indicate protein glycation associated with pathologic processes in diabetes as well as AMD, and alterations in the fluorescence of collagen and elastin in connective tissue give us the opportunity to observe fibrosis by fluorescence imaging. This, however, needs techniques able to differentiate particular fluorophores despite limited permissible ocular exposure as well as excitation wavelength (limited by the transmission of the human ocular lens to >400 nm). We present an ophthalmic laser scanning system (SLO), equipped with picosecond laser diodes (FWHM 100 ps, 446 nm or 468 nm respectively) and time correlated single photon counting (TCSPC) in two emission bands (500 - 560 nm and 560 - 700 nm). The decays were fitted by a bi-exponential model. Fluorescence spectra were measured by a fluorescence spectrometer fluorolog. Upon excitation at 446 nm, the fluorescence of AGE, FAD, and lipofuscin were found to peak at 503 nm, 525 nm, and 600 nm respectively. Accordingly, the statistical distribution of the fluorescence decay times was found to depend on the different excitation wavelengths and emission bands used. The use of multiple excitation and emission wavelengths in conjunction with fluorescence lifetime imaging allows us to discriminate between intrinsic fluorophores of the ocular fundus. Taken together with our knowledge on the anatomical structure of the fundus, these findings suggest an association of the short, middle and long fluorescence decay time to the retinal pigment epithelium, the retina, and connective tissue respectively.

  15. Room-temperature nine-µm-wavelength photodetectors and GHz-frequency heterodyne receivers

    Science.gov (United States)

    Palaferri, Daniele; Todorov, Yanko; Bigioli, Azzurra; Mottaghizadeh, Alireza; Gacemi, Djamal; Calabrese, Allegra; Vasanelli, Angela; Li, Lianhe; Davies, A. Giles; Linfield, Edmund H.; Kapsalidis, Filippos; Beck, Mattias; Faist, Jérôme; Sirtori, Carlo

    2018-04-01

    Room-temperature operation is essential for any optoelectronics technology that aims to provide low-cost, compact systems for widespread applications. A recent technological advance in this direction is bolometric detection for thermal imaging, which has achieved relatively high sensitivity and video rates (about 60 hertz) at room temperature. However, owing to thermally induced dark current, room-temperature operation is still a great challenge for semiconductor photodetectors targeting the wavelength band between 8 and 12 micrometres, and all relevant applications, such as imaging, environmental remote sensing and laser-based free-space communication, have been realized at low temperatures. For these devices, high sensitivity and high speed have never been compatible with high-temperature operation. Here we show that a long-wavelength (nine micrometres) infrared quantum-well photodetector fabricated from a metamaterial made of sub-wavelength metallic resonators exhibits strongly enhanced performance with respect to the state of the art up to room temperature. This occurs because the photonic collection area of each resonator is much larger than its electrical area, thus substantially reducing the dark current of the device. Furthermore, we show that our photonic architecture overcomes intrinsic limitations of the material, such as the drop of the electronic drift velocity with temperature, which constrains conventional geometries at cryogenic operation. Finally, the reduced physical area of the device and its increased responsivity allow us to take advantage of the intrinsic high-frequency response of the quantum detector at room temperature. By mixing the frequencies of two quantum-cascade lasers on the detector, which acts as a heterodyne receiver, we have measured a high-frequency signal, above four gigahertz (GHz). Therefore, these wide-band uncooled detectors could benefit technologies such as high-speed (gigabits per second) multichannel coherent data

  16. A long-wavelength target station for the spallation neutron source

    International Nuclear Information System (INIS)

    Carpenter, J.M.; Mason, T.E.

    2005-01-01

    The Spallation Neutron Source (SNS), a major new user facility for studies of the structure and dynamics of materials, funded by the US Department of Energy (DOE), is under construction at Oak Ridge National Laboratory (ORNL). Details about the project are available in a recent paper and on the SNS Web site [MRS Bull. 28 (12) (2003) 923]. A Long-Wavelength Target Station (LWTS) [Technical Concepts for a Long-Wavelength Target Station for the Spallation Neutron Source, Argonne National Laboratory Report ANL-02/16, Oak Ridge National Laboratory Report ORNL/SNS-TM-2001/163, November 2002. See also www.pns.anl.gov/related/] will complement the High-Power Target Station (HPTS) facility of the SNS and will build upon the significant investment in the remainder of the installation by providing important new scientific opportunities. For areas of science using the optimized long-wavelength beam lines, the LWTS will at least double the overall scientific capability of the SNS and provide for up to an order of magnitude performance gain over the initial HPTS. The fully equipped SNS has the prospect to offer capabilities for neutron-scattering studies of the structure and dynamics of materials with sensitivity, resolution, dynamic range, and speed that are unparalleled in the world. Preliminary assessments of the performance of the several instruments treated in detail in the body of the paper bear out this expectation. The LWTS concept has been developed in close consultation with the scientific community through a series of workshops and conferences jointly sponsored by DOE's Office of Basic Energy Science and the National Science Foundation. We describe the principal features of the LWTS concept, and provide a preliminary summary of some neutron scattering instruments suited to exploit the unique features of the LWTS. It remains to develop concepts and designs for a full suite of instruments that exploit the capabilities of LWTS, a process that has begun in collaboration

  17. Many faces of compact objects: distance, optical extinction and multi-wavelength behaviour

    International Nuclear Information System (INIS)

    Corbel, Stephane

    1999-01-01

    This thesis is devoted to a multi-wavelength study of accretion-ejection phenomena around compact stars (black holes and neutron stars). The first part of this manuscript describes problems related to the determination of the distance and the optical extinction to compact objects - fundamental parameters for the evaluation of the energy budget of these systems. To this end, the structure and the dynamics of the Galaxy are studied by observations of the atomic and molecular gas along the line of sight to compact stars. This method leads to the first evaluation of the distance to two Soft Gamma Repeaters: SGR 1806-20 and SGR 1627-41. We then draw some conclusions on the nature of these sources of recurrent gamma-ray bursts. The above method is then applied to two X-ray binaries: Cir X-1 and GX 339-4. In the second part of this thesis, we present a multi-wavelength study of the Galactic black hole candidate GX 339-4. We first discuss the characteristics of the radio emission from GX 339-4. In 1998, GX 339-4 underwent a transition to a soft-high X-ray state and observations in three wavelength regimes (radio, soft and hard X-rays) revealed new patterns of behaviour. This allowed us to constrain the region of origin of the radio emission (a compact jet) in GX 339-4 and allowed a better understanding of the physical coupling between accretion and ejection in GX 339-4. An analogy with the black hole candidate Cyg X-1 is then presented. Finally, these results are discussed in the context of micro-quasars and active galactic nuclei in order to gain a deeper insight into the accretion-ejection coupling around compact objects. (author) [fr

  18. Derivation of gravity wave intrinsic parameters and vertical wavelength using a single scanning OH(3-1) airglow spectrometer

    Science.gov (United States)

    Wüst, Sabine; Offenwanger, Thomas; Schmidt, Carsten; Bittner, Michael; Jacobi, Christoph; Stober, Gunter; Yee, Jeng-Hwa; Mlynczak, Martin G.; Russell, James M., III

    2018-05-01

    For the first time, we present an approach to derive zonal, meridional, and vertical wavelengths as well as periods of gravity waves based on only one OH* spectrometer, addressing one vibrational-rotational transition. Knowledge of these parameters is a precondition for the calculation of further information, such as the wave group velocity vector.OH(3-1) spectrometer measurements allow the analysis of gravity wave ground-based periods but spatial information cannot necessarily be deduced. We use a scanning spectrometer and harmonic analysis to derive horizontal wavelengths at the mesopause altitude above Oberpfaffenhofen (48.09° N, 11.28° E), Germany for 22 nights in 2015. Based on the approximation of the dispersion relation for gravity waves of low and medium frequencies and additional horizontal wind information, we calculate vertical wavelengths. The mesopause wind measurements nearest to Oberpfaffenhofen are conducted at Collm (51.30° N, 13.02° E), Germany, ca. 380 km northeast of Oberpfaffenhofen, by a meteor radar.In order to compare our results, vertical temperature profiles of TIMED-SABER (thermosphere ionosphere mesosphere energetics dynamics, sounding of the atmosphere using broadband emission radiometry) overpasses are analysed with respect to the dominating vertical wavelength.

  19. Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry

    Science.gov (United States)

    Kindt, Joel D.

    A microfluidic refractometer was designed based on previous optofluidic intracavity spectroscopy (OFIS) chips utilized to distinguish healthy and cancerous cells. The optofluidic cavity is realized by adding high reflectivity dielectric mirrors to the top and bottom of a microfluidic channel. This creates a plane-plane Fabry-Perot optical cavity in which the resonant wavelengths are highly dependent on the optical path length inside the cavity. Refractometry is a useful method to determine the nature of fluids, including the concentration of a solute in a solvent as well as the temperature of the fluid. Advantages of microfluidic systems are the easy integration with lab-on-chip devices and the need for only small volumes of fluid. The unique abilities of the microfluidic refractometer in this thesis include its spatial, temperature, and wavelength dependence. Spatial dependence of the transmission spectrum is inherent through a spatial filtering process implemented with an optical fiber and microscope objective. A sequence of experimental observations guided the change from using the OFIS chip as a cell discrimination device to a complimentary refractometer. First, it was noted the electrode structure within the microfluidic channel, designed to trap and manipulate biological cells with dielectrophoretic (DEP) forces, caused the resonant wavelengths to blue-shift when the electrodes were energized. This phenomenon is consistent with the negative dn/dT property of water and water-based solutions. Next, it was necessary to develop a method to separate the optical path length into physical path length and refractive index. Air holes were placed near the microfluidic channel to exclusively measure the cavity length with the known refractive index of air. The cavity length was then interpolated across the microfluidic channel, allowing any mechanical changes to be taken into account. After the separation of physical path length and refractive index, it was of interest

  20. Temperature and current coefficients of lasing wavelength in tunable diode laser spectroscopy.

    Science.gov (United States)

    Fukuda, M; Mishima, T; Nakayama, N; Masuda, T

    2010-08-01

    The factors determining temperature and current coefficients of lasing wavelength are investigated and discussed under monitoring CO(2)-gas absorption spectra. The diffusion rate of Joule heating at the active layer to the surrounding region is observed by monitoring the change in the junction voltage, which is a function of temperature and the wavelength (frequency) deviation under sinusoidal current modulation. Based on the experimental results, the time interval of monitoring the wavelength after changing the ambient temperature or injected current (scanning rate) has to be constant at least to eliminate the monitoring error induced by the deviation of lasing wavelength, though the temperature and current coefficients of lasing wavelength differ with the rate.

  1. Areca nut is associated with younger age of diagnosis, poor chemoradiotherapy response, and shorter overall survival in esophageal squamous cell carcinoma.

    Directory of Open Access Journals (Sweden)

    Chang-Han Chen

    Full Text Available Areca nut chewing is carcinogenic to humans. However, little is known about the impact of areca nut chewing on esophageal squamous cell carcinoma (ESCC.We retrospectively reviewed 286 ESCC patients who received surgery or preoperative chemoradiotherapy followed by surgery at our institution. Background characteristics including areca nut chewing history were analyzed. The 4-nitroquinoline 1-oxide (4-NQO-induced murine ESCC model was used to test the impact of arecoline, a main constituent of areca nut, on ESCC.Compared to patients without areca nut chewing history, patients with areca nut chewing history had overall a younger age of onset (Mean age: 56.75 versus 52.68 yrs, P<0.001 and significantly worse overall survival than those without areca nut chewing history (P = 0.026. Among patients who received surgery, the overall survival rates were not significantly different between those with or without areca nut chewing history. Among patients who received preoperative chemoradiotherapy followed by surgery, those with areca nut chewing history had a significantly lower pathologic complete response rate (P = 0.002 and lower overall survival rate (P = 0.002 than those without. In the murine ESCC model, the incidence of esophageal invasive squamous cell carcinoma was 40% in mice exposed to concomitant 4-NQO and arecoline treatment for 8 weeks and 6% in mice exposed to 4-NQO only for 8 weeks (P = 0.037.Our results indicate that areca nut chewing history is significantly associated with younger age of onset, poor response to chemoradiotherapy, and shorter overall survival in ESCC patients. Arecoline, a main constituent of areca nut, accelerates esophageal tumorigenesis in the 4-NQO-induced murine ESCC model.

  2. One Gene and Two Proteins: a Leaderless mRNA Supports the Translation of a Shorter Form of the Shigella VirF Regulator

    Directory of Open Access Journals (Sweden)

    Maria Letizia Di Martino

    2016-11-01

    Full Text Available VirF, an AraC-like activator, is required to trigger a regulatory cascade that initiates the invasive program of Shigella spp., the etiological agents of bacillary dysentery in humans. VirF expression is activated upon entry into the host and depends on many environmental signals. Here, we show that the virF mRNA is translated into two proteins, the major form, VirF30 (30 kDa, and the shorter VirF21 (21 kDa, lacking the N-terminal segment. By site-specific mutagenesis and toeprint analysis, we identified the translation start sites of VirF30 and VirF21 and showed that the two different forms of VirF arise from differential translation. Interestingly, in vitro and in vivo translation experiments showed that VirF21 is also translated from a leaderless mRNA (llmRNA whose 5′ end is at position +309/+310, only 1 or 2 nucleotides upstream of the ATG84 start codon of VirF21. The llmRNA is transcribed from a gene-internal promoter, which we identified here. Functional analysis revealed that while VirF30 is responsible for activation of the virulence system, VirF21 negatively autoregulates virF expression itself. Since VirF21 modulates the intracellular VirF levels, this suggests that transcription of the llmRNA might occur when the onset of the virulence program is not required. We speculate that environmental cues, like stress conditions, may promote changes in virF mRNA transcription and preferential translation of llmRNA.

  3. All-optical multi-wavelength conversion with negative power penalty by a commercial SOA-MZI for WDM wavelength multicast

    NARCIS (Netherlands)

    Yan, N.; Jung, H.D.; Tafur Monroy, I.; Waardt, de H.; Koonen, A.M.J.

    2007-01-01

    WDM wavelength multicast is demonstrated by all-optical multi-wavelength conversion at 10 Gb/s using a commercial SOA-MZI. We report for the first time simultaneous one-to-four conversion with negative power penalty of 1.84 dB.

  4. The power of the kashrut: older but shorter. The impact of religious nutritional and hygienic rules on stature and life expectancy of Jewish conscripts in the early 19th century.

    Science.gov (United States)

    Tassenaar, V; Karel, E H

    2016-06-01

    We test the impact of several demographic, economic and social factors on stature in an early nineteenth century environment. We use a database of conscripts from the period 1818-1860 of a rural province in The Netherlands (Drenthe). This area had a rather high biological standard of living. This database of 413 conscripts contains information about family structure, family rank order, height, tax income, occupation and age of death. Conscripts came from two communities: one from a particular village (Oosterhesselen) and the other was Jewish conscripts that came from the countryside of the province. Our statistical analysis shows a positive significant relationship between family size and height, which confirms the resource dilution theory. Remarkably, the sign of the relation between family size and life expectancy is inverse. Other factors such as the potato crisis and income had the expected effect on conscript heights. The community effect was strong. Jewish conscripts were much shorter than their counterparts. Access to nutrition, the specific food laws and other factors can explain this difference. An increasing sibship size had a negative impact on body height but positive effects on life expectancy when adulthood was reached. Specifically for the Jewish community was the positive effect of the death of the father on conscript height. The mechanisms behind this phenomenon are unclear and open for further research.

  5. High-Sensitivity AGN Polarimetry at Sub-Millimeter Wavelengths

    Directory of Open Access Journals (Sweden)

    Ivan Martí-Vidal

    2017-10-01

    Full Text Available The innermost regions of radio loud Active Galactic Nuclei (AGN jets are heavily affected by synchrotron self-absorption, due to the strong magnetic fields and high particle densities in these extreme zones. The only way to overcome this absorption is to observe at sub-millimeter wavelengths, although polarimetric observations at such frequencies have so far been limited by sensitivity and calibration accuracy. However, new generation instruments such as the Atacama Large mm/sub-mm Array (ALMA overcome these limitations and are starting to deliver revolutionary results in the observational studies of AGN polarimetry. Here we present an overview of our state-of-the-art interferometric mm/sub-mm polarization observations of AGN jets with ALMA (in particular, the gravitationally-lensed sources PKS 1830−211 and B0218+359, which allow us to probe the magneto-ionic conditions at the regions closest to the central black holes.

  6. Long-wavelength germanium photodetectors by ion implantation

    International Nuclear Information System (INIS)

    Wu, I.C.; Beeman, J.W.; Luke, P.N.; Hansen, W.L.; Haller, E.E.

    1990-11-01

    Extrinsic far-infrared photoconductivity in thin high-purity germanium wafers implanted with multiple-energy boron ions has been investigated. Initial results from Fourier transform spectrometer(FTS) measurements have demonstrated that photodetectors fabricated from this material have an extended long-wavelength threshold near 192μm. Due to the high-purity substrate, the ability to block the hopping conduction in the implanted IR-active layer yields dark currents of less than 100 electrons/sec at temperatures below 1.3 K under an operating bias of up to 70 mV. Optimum peak responsivity and noise equivalent power (NEP) for these sensitive detectors are 0.9 A/W and 5 x 10 -16 W/Hz 1/2 at 99 μm, respectively. The dependence of the performance of devices on the residual donor concentration in the implanted layer will be discussed. 12 refs., 4 figs

  7. Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging

    Science.gov (United States)

    Chattopadhyay, Goutam; Gill, John J.; Skalare, Anders; Lee, Choonsup; Llombart, Nuria; Siegel, Peter H.

    2011-01-01

    Most optical systems require antennas with directive patterns. This means that the physical area of the antenna will be large in terms of the wavelength. When non-cooled systems are used, the losses of microstrip or coplanar waveguide lines impede the use of standard patch or slot antennas for a large number of elements in a phased array format. Traditionally, this problem has been solved by using silicon lenses. However, if an array of such highly directive antennas is to be used for imaging applications, the fabrication of many closely spaced lenses becomes a problem. Moreover, planar antennas are usually fed by microstrip or coplanar waveguides while the mixer or the detector elements (usually Schottky diodes) are coupled in a waveguide environment. The coupling between the antenna and the detector/ mixer can be a fabrication challenge in an imaging array at submillimeter wavelengths. Antennas excited by a waveguide (TE10) mode makes use of dielectric superlayers to increase the directivity. These antennas create a kind of Fabry- Perot cavity between the ground plane and the first layer of dielectric. In reality, the antenna operates as a leaky wave mode where a leaky wave pole propagates along the cavity while it radiates. Thanks to this pole, the directivity of a small antenna is considerably enhanced. The antenna consists of a waveguide feed, which can be coupled to a mixer or detector such as a Schottky diode via a standard probe design. The waveguide is loaded with a double-slot iris to perform an impedance match and to suppress undesired modes that can propagate on the cavity. On top of the slot there is an air cavity and on top, a small portion of a hemispherical lens. The fractional bandwidth of such antennas is around 10 percent, which is good enough for heterodyne imaging applications.The new geometry makes use of a silicon lens instead of dielectric quarter wavelength substrates. This design presents several advantages when used in the submillimeter

  8. Long-wavelength Radar Studies of the Lunar Maria

    Science.gov (United States)

    Campbell, Bruce A.; Hawke, B. Ray; Thompson, Thomas W.

    1995-01-01

    Radar measurements at 70 cm and 7.5 m wavelengths provide insight into the structure and chemical properties of the upper 5-100 m of the lunar regolith and crust. Past work has identified a number of anomalous regions and changes in echo strength, some attributed to differences in titanium content. There has been little opportunity, however, to compare calibrated long-wavelength backscatter among different units or to theoretical model results. We combine recent high-resolution (3-5 km) 70-cm radar data for the nearside with earlier calibrated full-disk observations to provide a reasonable estimate of the true lunar backscatter coefficient. These data are tested against models for quasi-specular scattering from the surface, echoes from a buried substrate, and Mie scattering from surface and buried rocks. We find that 70 cm echoes likely arise from Mie scattering by distributed rocks within the soil, consistent with earlier hypotheses. Returns from a buried substrate would provide a plausible fit to the observations only if the regolith depth were 3 m or less and varied little across the maria. Depolarized echoes are due to some combination of single and multiple scattering events, but it appears that single scattering alone could account for the observed echo power, based on comparisons with terrestrial rocky surfaces. Backscatter strength from the regolith is most strongly affected by the loss tangent, whose variation with mineral content is still poorly defined. We compared the backscatter values for the mare deposits to the oxide contents inferred from spectral ratio methods, and found that in general the unit boundaries evident in radar images closely follow those seen in color difference images. The 70-cm data are not well correlated with TiO2 values found using the Charette relationship nor with Fe abundances derived from Clementine observations. The lack of a relationship between radar echo and Fe content is reasonable given the distribution of iron among

  9. PMT signal increase using a wavelength shifting paint

    Energy Technology Data Exchange (ETDEWEB)

    Allada, K. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hurlbut, Ch. [Eljen Technology, Sweetwater, TX 79556 (United States); Ou, L.; Schmookler, B. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Shahinyan, A. [Yerevan Physics Institute, Yerevan (Armenia); Wojtsekhowski, B., E-mail: bogdanw@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

    2015-05-11

    We report a 1.65 times increase of the PMT signal and a simple procedure of application of a new wavelength shifting (WLS) paint for PMTs with non-UV-transparent windows. Samples of four different WLS paints, made from hydrocarbon polymers and organic fluors, were tested on a 5-in. PMT (ET 9390KB) using Cherenkov radiation produced in fused silica disks by {sup 106}Ru electrons on a ‘table-top’ setup. The best performing paint was employed on two different types of 5-in. PMTs (ET 9390KB and XP4572B), installed in atmospheric pressure CO{sub 2} gas Cherenkov detectors, and tested using GeV electrons.

  10. A SURVEY ON WAVELENGTH DIVISION MULTIPLEXING (WDM NETWORKS

    Directory of Open Access Journals (Sweden)

    G. Ramesh

    2010-03-01

    Full Text Available Communication networks have emerged as a source of empowerment in today’s society. At the global level, the Internet is becoming the backbone of the modern economy. The new generations in developed countries cannot even conceive of a world without broadband access to the Internet. The inability of the current Internet infrastructure to cope with the wide variety and ever growing number of users, emerging networked applications, usage patterns and business models is increasingly being recognized worldwide. The dynamic growth of Internet traffic and its bursty nature requires high transmission rate. With the advances and the progress in Wavelength Division Multiplexing (WDM technology, the amount of raw bandwidth available in fiber links has increased to high magnitude. This paper presents a survey on WDM networks from its development to the current status. Also an analysis on buffer size in optical networks for real time traffic was performed.

  11. All-fiber femtosecond Cherenkov laser at visible wavelengths

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe Visbech

    2013-01-01

    -matching condition [1]. The resonant ultrafast wave conversion via the fiber-optic CR mechanism is instrumental for applications in biophotonics such as bio-imaging and microscopy [2]. In this work, we demonstrate a highly-stable all-fiber, fully monolithic CR system based on an Yb-fiber femtosecond laser, producing...... to be as low as -103 dBc/Hz. This is 2 orders of magnitudes lower noise as compared to spectrally-sliced supercontinuum, which is the current standard of ultrafast fiber-optic generation at visible wavelength. The layout of the laser system is shown in Fig. 1(a). The system consists of two parts: an all-fiber......Fiber-optic Cherenkov radiation (CR), also known as dispersive wave generation or non-solitonic radiation, is produced in small-core photonic crystal fibers (PCF) when a soliton perturbed by fiber higher-order dispersion co-propagates with a dispersive wave fulfilling a certain phase...

  12. Accuracy optimization with wavelength tunability in overlay imaging technology

    Science.gov (United States)

    Lee, Honggoo; Kang, Yoonshik; Han, Sangjoon; Shim, Kyuchan; Hong, Minhyung; Kim, Seungyoung; Lee, Jieun; Lee, Dongyoung; Oh, Eungryong; Choi, Ahlin; Kim, Youngsik; Marciano, Tal; Klein, Dana; Hajaj, Eitan M.; Aharon, Sharon; Ben-Dov, Guy; Lilach, Saltoun; Serero, Dan; Golotsvan, Anna

    2018-03-01

    As semiconductor manufacturing technology progresses and the dimensions of integrated circuit elements shrink, overlay budget is accordingly being reduced. Overlay budget closely approaches the scale of measurement inaccuracies due to both optical imperfections of the measurement system and the interaction of light with geometrical asymmetries of the measured targets. Measurement inaccuracies can no longer be ignored due to their significant effect on the resulting device yield. In this paper we investigate a new approach for imaging based overlay (IBO) measurements by optimizing accuracy rather than contrast precision, including its effect over the total target performance, using wavelength tunable overlay imaging metrology. We present new accuracy metrics based on theoretical development and present their quality in identifying the measurement accuracy when compared to CD-SEM overlay measurements. The paper presents the theoretical considerations and simulation work, as well as measurement data, for which tunability combined with the new accuracy metrics is shown to improve accuracy performance.

  13. Phase and fringe order determination in wavelength scanning interferometry.

    Science.gov (United States)

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-04-18

    A method to obtain unambiguous surface height measurements using wavelength scanning interferometry with an improved repeatability, comparable to that obtainable using phase shifting interferometry, is reported. Rather than determining the conventional fringe frequency-derived z height directly, the method uses the frequency to resolve the fringe order ambiguity, and combine this information with the more accurate and repeatable fringe phase derived z height. A theoretical model to evaluate the method's performance in the presence of additive noise is derived and shown to be in good agreement with experiments. The measurement repeatability is improved by a factor of ten over that achieved when using frequency information alone, reaching the sub-nanometre range. Moreover, the z-axis non-linearity (bleed-through or ripple error) is reduced by a factor of ten. These order of magnitude improvements in measurement performance are demonstrated through a number of practical measurement examples.

  14. Estimation of Snow Parameters from Dual-Wavelength Airborne Radar

    Science.gov (United States)

    Liao, Liang; Meneghini, Robert; Iguchi, Toshio; Detwiler, Andrew

    1997-01-01

    Estimation of snow characteristics from airborne radar measurements would complement In-situ measurements. While In-situ data provide more detailed information than radar, they are limited in their space-time sampling. In the absence of significant cloud water contents, dual-wavelength radar data can be used to estimate 2 parameters of a drop size distribution if the snow density is assumed. To estimate, rather than assume, a snow density is difficult, however, and represents a major limitation in the radar retrieval. There are a number of ways that this problem can be investigated: direct comparisons with in-situ measurements, examination of the large scale characteristics of the retrievals and their comparison to cloud model outputs, use of LDR measurements, and comparisons to the theoretical results of Passarelli(1978) and others. In this paper we address the first approach and, in part, the second.

  15. Quantum metropolitan optical network based on wavelength division multiplexing.

    Science.gov (United States)

    Ciurana, A; Martínez-Mateo, J; Peev, M; Poppe, A; Walenta, N; Zbinden, H; Martín, V

    2014-01-27

    Quantum Key Distribution (QKD) is maturing quickly. However, the current approaches to its application in optical networks make it an expensive technology. QKD networks deployed to date are designed as a collection of point-to-point, dedicated QKD links where non-neighboring nodes communicate using the trusted repeater paradigm. We propose a novel optical network model in which QKD systems share the communication infrastructure by wavelength multiplexing their quantum and classical signals. The routing is done using optical components within a metropolitan area which allows for a dynamically any-to-any communication scheme. Moreover, it resembles a commercial telecom network, takes advantage of existing infrastructure and utilizes commercial components, allowing for an easy, cost-effective and reliable deployment.

  16. The At-Wavelength Metrology Facility at BESSY-II

    Directory of Open Access Journals (Sweden)

    Franz Schäfers

    2016-02-01

    Full Text Available The At-Wavelength Metrology Facility at BESSY-II is dedicated to short-term characterization of novel UV, EUV and XUV optical elements, such as diffraction gratings, mirrors, multilayers and nano-optical devices like reflection zone plates. It consists of an Optics Beamline PM-1 and a Reflectometer in a clean-room hutch as a fixed end station. The bending magnet Beamline is a Plane Grating Monochromator beamline (c-PGM equipped with an SX700 monochromator. The beamline is specially tailored for efficient high-order suppression and stray light reduction. The versatile 11-axes UHV-Reflectometer can house life-sized optical elements, which are fully adjustable and of which the reflection properties can be measured in the full incidence angular range as well as in the full azimuthal angular range to determine polarization properties.

  17. Wavelength dispersive μPIXE setup for the ion microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Fazinić, S., E-mail: stjepko.fazinic@irb.hr [Laboratory for Ion Beam Interactions, Division of Experimental Physics, Rudjer Bošković Institute, Bijenicka cesta 54, 10000 Zagreb (Croatia); Božičević Mihalić, I.; Tadić, T.; Cosic, D.; Jakšić, M. [Laboratory for Ion Beam Interactions, Division of Experimental Physics, Rudjer Bošković Institute, Bijenicka cesta 54, 10000 Zagreb (Croatia); Mudronja, D. [Croatian Conservation Institute, Grškovićeva 23, 10000 Zagreb (Croatia)

    2015-11-15

    We have developed a small wavelength dispersive X-ray spectrometer to explore the possibility of performing chemical speciation on microscopic samples utilizing focused ion beams available at the Rudjer Boskovic Institute ion microprobe. Although PIXE spectra are in principle chemically invariant, small influence of chemical effects could be observed even with Si(Li) or SDD detectors. Such chemical effects can be clearly seen with high resolution crystal X-ray spectrometers having energy resolution of several eV. A dedicated vacuum chamber, housing the diffraction crystal, sample holder and CCD X-ray detector, was constructed and positioned behind the main ion microprobe vacuum chamber. Here we will briefly describe the spectrometer, and illustrate its capabilities on measured K X-ray spectra of selected sulfur compounds. We will also demonstrate its abilities to resolve K and M X-ray lines irresolvable by solid state ED detectors usually used in PIXE.

  18. Laser frequency stabilization using a commercial wavelength meter

    Science.gov (United States)

    Couturier, Luc; Nosske, Ingo; Hu, Fachao; Tan, Canzhu; Qiao, Chang; Jiang, Y. H.; Chen, Peng; Weidemüller, Matthias

    2018-04-01

    We present the characterization of a laser frequency stabilization scheme using a state-of-the-art wavelength meter based on solid Fizeau interferometers. For a frequency-doubled Ti-sapphire laser operated at 461 nm, an absolute Allan deviation below 10-9 with a standard deviation of 1 MHz over 10 h is achieved. Using this laser for cooling and trapping of strontium atoms, the wavemeter scheme provides excellent stability in single-channel operation. Multi-channel operation with a multimode fiber switch results in fluctuations of the atomic fluorescence correlated to residual frequency excursions of the laser. The wavemeter-based frequency stabilization scheme can be applied to a wide range of atoms and molecules for laser spectroscopy, cooling, and trapping.

  19. Plasmonic Nanowires for Wide Wavelength Range Molecular Sensing

    KAUST Repository

    Marinaro, Giovanni

    2018-05-17

    In this paper, we propose the use of a standing nanowires array, constituted by plasmonic active gold wires grown on iron disks, and partially immersed in a supporting alumina matrix, for surface-enhanced Raman spectroscopy applications. The galvanic process was used to fabricate nanowires in pores of anodized alumina template, making this device cost-effective. This fabrication method allows for the selection of size, diameter, and spatial arrangement of nanowires. The proposed device, thanks to a detailed design analysis, demonstrates a broadband plasmonic enhancement effect useful for many standard excitation wavelengths in the visible and NIR. The trigonal pores arrangement gives an efficiency weakly dependent on polarization. The devices, tested with 633 and 830 nm laser lines, show a significant Raman enhancement factor, up to around 6 × 10⁴, with respect to the flat gold surface, used as a reference for the measurements of the investigated molecules.

  20. Single-photon generator for optical telecommunication wavelength

    International Nuclear Information System (INIS)

    Usuki, T; Sakuma, Y; Hirose, S; Takemoto, K; Yokoyama, N; Miyazawa, T; Takatsu, M; Arakawa, Y

    2006-01-01

    We report on the generation of single-photon pulses from a single InAs/InP quantum dot in telecommunication bands (1.3-1.55 μm: higher transmittance through an optical fiber). First we prepared InAs quantum dots on InP (0 0 1) substrates in a low-pressure MOCVD by using a so-called InP 'double-cap' procedure. The quantum dots have well-controlled photo emission wavelength in the telecommunication bands. We also developed a single-photon emitter in which quantum dots were embedded. Numerical simulation designed the emitter to realize efficient injection of the emitted photons into a single-mode optical fiber. Using a Hanbury-Brown and Twiss technique has proved that the photons through the fiber were single photons