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1

Age Effect on Retina and Optic Disc Normal Values  

Microsoft Academic Search

Purpose: To investigate retinal thickness and optic disc parameters by the Retinal Thickness Analyzer (RTA) glaucoma program in older normal subjects and to determine any age effect. Methods: Subjects over 40 years of age without any prior history of eye diseases were recruited. Only subjects completely normal on clinical ophthalmologic examination and on visual field testing by Humphrey Field Analyzer

Aljoscha S. Neubauer; Christos Chryssafis; Martin Thiel; Ioannis Tsinopoulos; Christoph Hirneiss; Anselm Kampik

2005-01-01

2

Abnormalities of the optic disc  

Microsoft Academic Search

The optic disc represents the anterior end of the optic nerve, the most forward extension of the central nervous system (CNS). The optic disc gives a rare glimpse into the CNS. Hence, diseases of the CNS are often manifested on fundus examination. Abnormalities of the optic disc may reflect eye disease (such as glaucoma), problems in development (as in various

Alfredo A. Sadun; Michelle Y. Wang

2011-01-01

3

The Chemistry of Optical Discs.  

ERIC Educational Resources Information Center

Explains the chemistry used in compact discs (CD), digital versatile discs (DVD), and magneto-optical (MO) discs focusing on the steps of initial creation of the mold, the molding of the polycarbonate, the deposition of the reflective layers, the lacquering of the CDs, and the bonding of DVDs. (Contains 15 references.) (YDS)

Birkett, David

2002-01-01

4

Medical Information on Optical Disc*  

PubMed Central

Optical discs may permit a revolutionary change in the distribution and use of medical information. A single compact disc, similar in size to that used for digital audio recording, can contain over 500 million characters of information that is accessible by a Personal Computer. These discs can be manufactured at a cost lower than that of print on paper, at reasonable volumes. Software can provide the health care professional with nearly instantaneous access to the information. Thus, for the first time, the opportunity exists to have large local medical information collections. This paper describes an application of this technology in the field of Oncology.

Schipma, Peter B.; Cichocki, Edward M.; Ziemer, Susan M.

1987-01-01

5

The Optical Disc Roundup.  

ERIC Educational Resources Information Center

Provides an update on optical disk technology as a means of digital media storage and explains why it may become a standard storage technology for telemedia technology. Topics discussed include read-only formats; write-once formats, including WORM and CD-WORM; rewritable formats; videodiscs; and future possibilities. (LRW)

Galbreath, Jeremy

1993-01-01

6

Computer animation via optical video disc  

E-print Network

This paper explores the notion of marrying two technologies: raster-scan computer animation and optical video discs. Animated sequences, generated at non real-time rates, then transfered to video disc, can be recalled under ...

Bender, Walter

1981-01-01

7

512 GB recording on 16-layer optical disc with Blu-ray Disc based optics  

Microsoft Academic Search

We confirmed the feasibility of a 16-layer write once disc based on Blu-ray Disc optics that was fabricated with inorganic recording material Bi-Ge-O. The total capacity of the disc achieved 400 GB and 512 GB per single disc side with BD 1x recording speed utilizing conventional BD technique.

Motohiro Inoue; Atsuko Kosuda; Koji Mishima; Tomoki Ushida; Takashi Kikukawa

2010-01-01

8

512 GB recording on 16-layer optical disc with Blu-ray Disc based optics  

NASA Astrophysics Data System (ADS)

We confirmed the feasibility of a 16-layer write once disc based on Blu-ray Disc optics that was fabricated with inorganic recording material Bi-Ge-O. The total capacity of the disc achieved 400 GB and 512 GB per single disc side with BD 1x recording speed utilizing conventional BD technique.

Inoue, Motohiro; Kosuda, Atsuko; Mishima, Koji; Ushida, Tomoki; Kikukawa, Takashi

2010-06-01

9

Reading of cracked optical discs using Iterative Learning Control  

Microsoft Academic Search

Optical discs, including Compact Discs (CDs), Digital Versatile Discs (DVDs), and Blu-ray Discs (BDs), can get cracked during storage and usage. Such cracks commonly lead to discontinuities in the data track, potentially preventing reading of the data on the disc. The aim of the present paper is to improve tracking performance of the optical disc drive in the presence of

Maarten Steinbuch; Koos van Berkel; George Leenknegt; TAE Oomen; Jeroen van de Wijdeven

2009-01-01

10

Miniaturized Optical Pickup and Mechanism for Mobile Optical Disc Drive  

Microsoft Academic Search

Recently, the market for portable instruments has been increasing markedly. If a very small optical disc drive can be realized, it is expected that a new market for memories will be created, because the running cost of an optical disc is very low. The main issues in such realization are miniaturization of a loading mechanism with a disc cartridge and

Mitsuhiro Togashi; Takayuki Sasaoka; Ho-Cheol Lee; Ho-Seop Jeong

2004-01-01

11

The cell biology of intervertebral disc aging and degeneration  

Microsoft Academic Search

Intervertebral disc degeneration, which mimics disc aging but occurs at an accelerated rate, is considered to be related to neck or low back pain and disc herniation. Degenerated discs show breakdown of the extracellular matrix and thus fail to bear the daily loadings exerted on the spine. Rather than a passive process of wear and tear, disc degeneration is an

Chang-Qing Zhao; Li-Min Wang; Lei-Sheng Jiang; Li-Yang Dai

2007-01-01

12

Pharmacological mydriasis and optic disc examination  

PubMed Central

AIM—To determine whether pharmacological mydriasis leads to a significant difference in interobserver agreement of optic disc measurement compared with examination without mydriasis.?METHOD—A cross sectional study was performed with a pair of observers examining the optic disc of two randomised groups of patients, one group before diagnostic mydriasis, and the other afterwards. Horizontal and vertical disc diameters and cup/disc ratios were measured with a 78 dioptre lens. The study was repeated with another observer pair and two further groups of patients.?RESULTS—In study A 86 subjects were examined in total (52 without and 34 with mydriasis). In study B 87 subjects were examined (45 without and 42 with mydriasis). The 95% limits of agreement of the cup/disc ratio measurement differences were significantly larger without mydriasis (p<0.001 for all studies (F test)). For both studies examination after mydriasis gave significantly greater agreement for vertical and horizontal cup/disc ratios. The cases with good agreement (0.1 difference or better) for vertical cup/disc ratios were 37/52 (72%) and 34 /45 (76%) without mydriasis and 33/34 (97%) and 40/42 (95%) respectively with mydriasis. Similar differences were recorded for horizontal cup/disc ratios. Disc diameter measurement results showed similar differences in study A but were not affected by mydriasis in study B.?CONCLUSIONS—Examination of the optic disc without pharmacological mydriasis gives significantly poorer interobserver agreement. In this study, the mean 95% limits of agreement values for all cup/disc ratio values were 0.27 for examination without mydriasis and 0.13 for examination with mydriasis. A measure outside these limits would suggest a real difference. This study indicates that mydriasis is important for reproducible clinical examination in glaucoma.?? PMID:10906099

Kirwan, J.; Gouws, P.; Linnell, A.; Crowston, J.; Bunce, C.

2000-01-01

13

Disc excavation in dominant optic atrophy  

Microsoft Academic Search

ObjectiveIn patients with dominant optic atrophy (DOA, Kjer type), excavation of the optic nerve develops, and these patients may be misdiagnosed as having normal tension glaucoma (NTG). This study examined disc morphologic features in patients with DOA and explored features that help distinguish this condition from NTG.

Annick V Fournier; Karim F Damji; David L Epstein; Stephen C Pollock

2001-01-01

14

Dependence of optic disc parameters on disc area according to Heidelberg Retina Tomograph: Part II.  

NASA Astrophysics Data System (ADS)

With the help of Heidelberg Retina Tomograph (HRT-II) optic disc parameters in 211 eyes of 115 healthy patients with refraction Em +/- 3,0 D and 96 eyes of 72 patients with myopia 3,5-14,0 D without any signs of glaucoma were studied. Analysis of optic disc parameters were carried out in 5 groups of patients according to disc area: less than 1,5 mm2, 1,5- 2,5 mm2, 2,5-3,0 mm2, 3,0-3,5 mm2 and more than 3,5 mm2. An accurate depending on disc area was revealed for all optic disc parameters in all sectors, which was manifested by increasing cup disc and rim disc (area and volume) and other parameters. We consider it is necessary to use the proper tables for right interpretation of received data for early diagnosis of glaucoma.

Machekhin, V.; Manaenkova, G.; Bondarenko, O.

2007-05-01

15

Study of optical destruction techniques for optical discs  

NASA Astrophysics Data System (ADS)

The topic of this dissertation is on the investigation of optical techniques for completely destroying data stored in optical discs. Complete and secure destruction of data is important when disposal of an optical disc containing sensitive and possibly classified information is concerned, since some information can be retrieved even from a fragment of a disc. After several candidate techniques and related systems are examined and fundamental system components are identified, an optical data destruction (ODD) system using a focused high power laser beam is devised, and a prototype system is designed and constructed. The ODD system uses a high power laser diode (HPLD) to expose data marks on optical discs and maintains the focused laser beam on a data layer by a focus servo using a diffractive optical element (DOE). The optical characteristics of the beam emitted from an HPLD are thoroughly investigated, and a few methods of modeling an HPLD beam in an optical system are studied. With the understanding of the HPLD beam properties, a limited-divergence raytracing (LDRT) model is developed to predict the propagation behavior of the HPLD beam in an optical system and shows good agreement with the real HPLD beam. This LDRT method is used to model the HPLD beam in the ODD system and simulate the resultant focus error signal with and without fabrication errors. The DOE focus sensor overcomes the problems in conventional focus sensors associated with the use of an intense line beam. The DOE comprising two angled gratings is designed to use only two weak 3rd order beams for focus sensing and fabricated on a chrome-coated glass substrate using a maskless lithography tool. The constructed ODD system is then used to perform destruction tests on various optical discs, which are examined using static and dynamic methods of data observation and retrieval. The observations show that data marks are optical invisible or completely covered with numerous micro-bubbles. These test results demonstrate that secure and complete destruction of data on optical discs is achieved using an ODD system. Successful destruction, however, depends greatly on exposure conditions and the type of optical media.

Choi, Taeyoung

16

Interactive Optical Disc Systems: Part 1: Analog Storage.  

ERIC Educational Resources Information Center

Details distinction between digital and analog data, advantages of analog storage, and optical disc use to store analog data. Configuration and potential of three levels of laser disc systems are explained. Selection of display devices for use with laser disc systems and accessing audio data are addressed. (Continued in next issue.) (EJS)

Hessler, David W.

1984-01-01

17

Comparison of Optic Disc Morphology of Optic Nerve Atrophy between Compressive Optic Neuropathy and Glaucomatous Optic Neuropathy  

PubMed Central

Objectives To compare the optic nerve head (ONH) structure between compressive optic neuropathy (CON) and glaucomatous optic neuropathy (GON), and to determine whether selected ONH quantitative parameters effectively discriminate between GON and CON, especially CON cases presenting with a glaucoma-like disc. Methods We prospectively assessed 34 patients with CON, 34 age-matched patients with moderate or severe GON, and 34 age-matched healthy control subjects. The quantitative parameters of ONH structure were compared using the Heidelberg Retina Tomograph 2 (HRT2) and Spectralis optical coherence tomography with an enhanced depth imaging method. Results The mean and maximum cup depths of CON were significantly smaller than those with GON (P<0.001 and P<0.001, respectively). The distance between Bruch's membrane opening and anterior surface of the lamina cribrosa (BMO-anterior LC) of CON was also significantly smaller than that of glaucoma but was similar to that of the healthy group (P<0.001 and P?=?0.47, respectively). Based on Moorfields regression analysis of the glaucoma classification of HRT2, 15 eyes with CON were classified with a glaucoma-like disc. The cup/disc area ratio did not differ between cases of CON with a glaucoma-like disc and cases of GON (P?=?0.16), but the BMO-anterior LC and mean and maximum cup depths of CON cases with a glaucoma-like disc were smaller than those in GON (P?=?0.005, P?=?0.003, and P?=?0.001, respectively). Conclusions Measurements of the cup depths and the LC depth had good ability to differentiate between CON with a glaucoma-like disc and glaucoma. There was no laminar remodeling detected by laminar surface position in the patients with CON compared to those with GON. PMID:25375855

Hata, Masayuki; Miyamoto, Kazuaki; Oishi, Akio; Makiyama, Yukiko; Gotoh, Norimoto; Kimura, Yugo; Akagi, Tadamichi; Yoshimura, Nagahisa

2014-01-01

18

Comparison of Optic Disc Margin Identified by Color Disc Photography and High-Speed Ultrahigh-Resolution Optical Coherence Tomography  

PubMed Central

Objective To determine the correspondence between optic disc margins evaluated using disc photography (DP) and optical coherence tomography (OCT). Methods From May 1, 2005, through November 10, 2005, 17 healthy volunteers (17 eyes) had raster scans (180 frames, 501 samplings per frame) centered on the optic disc taken with stereo-optic DP and high-speed ultrahigh-resolution OCT (hsUHR-OCT). Two image outputs were derived from the hsUHR-OCT data set: an en face hsUHR-OCT fundus image and a set of 180 frames of cross-sectional images. Three ophthalmologists independently and in a masked, randomized fashion marked the disc margin on the DP, hsUHR-OCT fundus, and cross-sectional images using custom software. Disc size (area and horizontal and vertical diameters) and location of the geometric disc center were compared among the 3 types of images. Results The hsUHR-OCT fundus image definition showed a significantly smaller disc size than the DP definition (P<.001, mixed-effects analysis). The hsUHR-OCT cross-sectional image definition showed a significantly larger disc size than the DP definition (P<.001). The geometric disc center location was similar among the 3 types of images except for the y-coordinate, which was significantly smaller in the hsUHR-OCT fundus images than in the DP images. Conclusion The optic disc margin as defined by hsUHR-OCT was significantly different than the margin defined by DP. PMID:18195219

Manassakorn, Anita; Ishikawa, Hiroshi; Kim, Jong S.; Wollstein, Gadi; Bilonick, Richard A.; Kagemann, Larry; Gabriele, Michelle L.; Sung, Kyung Rim; Mumcuoglu, Tarkan; Duker, Jay S.; Fujimoto, James G.; Schuman, Joel S.

2009-01-01

19

Pharmacological enhancement of disc diffusion and differentiation of healthy, ageing and degenerated discs  

Microsoft Academic Search

Degenerative disc disease (DDD) is still a poorly understood phenomenon because of the lack of availability of precise definition\\u000a of healthy, ageing and degenerated discs. Decreased nutrition is the final common pathway for DDD and the status of the endplate\\u000a (EP) plays a crucial role in controlling the extent of diffusion, which is the only source of nutrition. The vascular

S. Rajasekaran; K. Venkatadass; J. Naresh Babu; K. Ganesh; Ajoy P. Shetty

2008-01-01

20

Multilayer optical disc system using homodyne detection  

NASA Astrophysics Data System (ADS)

A write/read system using high-productivity multilayer optical discs was developed. The recording medium used in the system consists of planar recording layers and a separated guide layer, and is fabricated by web coating and lamination process. The recording layers in the medium are made of one-photon-absorption material, on which data can be recorded with a normal laser diode. The developed system is capable of focusing and tracking on the medium and amplifying readout signals by using phase-diversity homodyne detection. A highly layer-selective focusing method using homodyne detection was also proposed. This method obtains stable focus-error signals with clearly separated S-shaped curves even when layer spacing is quite narrow, causing large interlayer crosstalk. Writing on the medium and reading with the signal amplification effect of homodyne detection was demonstrated. In addition, the effectiveness of the method was experimentally evaluated.

Kurokawa, Takahiro; Ide, Tatsuro; Tanaka, Yukinobu; Watanabe, Koichi

2014-09-01

21

Optic disc detection using ant colony optimization  

NASA Astrophysics Data System (ADS)

The retinal fundus images are used in the treatment and diagnosis of several eye diseases, such as diabetic retinopathy and glaucoma. This paper proposes a new method to detect the optic disc (OD) automatically, due to the fact that the knowledge of the OD location is essential to the automatic analysis of retinal images. Ant Colony Optimization (ACO) is an optimization algorithm inspired by the foraging behaviour of some ant species that has been applied in image processing for edge detection. Recently, the ACO was used in fundus images to detect edges, and therefore, to segment the OD and other anatomical retinal structures. We present an algorithm for the detection of OD in the retina which takes advantage of the Gabor wavelet transform, entropy and ACO algorithm. Forty images of the retina from DRIVE database were used to evaluate the performance of our method.

Dias, Marcy A.; Monteiro, Fernando C.

2012-09-01

22

Preliminary optical coherence tomography investigation of the temporo-mandibular joint disc  

NASA Astrophysics Data System (ADS)

Aim and objectives. The morphology and position of the temporo-mandibular disc are key issues in the diagnosis and treatment of arthrogenous temporo-mandibular disorders. Magnetic resonance imaging and arthroscopy are used today to identify: flattening of the pars posterior of the disc, perforation and/or adhesions in the pars intermedia of the disc and disc displacements. The present study proposes the investigation of the temporo-mandibular joint disc by optical coherence tomography (OCT). Material and methods. 8 human temporo-mandibular joint discs were harvested from dead subjects, under 40 year of age, and conserved in formalin. They had a normal morphology, with a thicker pars posterior (2,6 mm on the average) and a thinner pars intermedia (1mm on the average). We investigated the disc samples using two different OCT systems: an en-face OCT (time domain (TD)-OCT) system, working at 1300 nm (C-scan and B-scan mode) and a spectral OCT system (a Fourier domain (FD)-OCT) system , working at 840 nm (B-scan mode). Results. The OCT investigation of the temporo-mandibular joint discs revealed a homogeneous microstructure. The longer wavelength of the TD-OCT offers a higher penetration depth (2,5 mm in air), which is important for the analysis of the pars posterior, while the FD-OCT is much faster. Conclusions: OCT is a promising imaging method for the microstructural characterization of the temporo-mandibular disc.

M?rc?uteanu, Corina; Demjan, Enikö; Sinescu, Cosmin; Negrutiu, Meda; Motoc, Adrian; Lighezan, Rodica; Vasile, Liliana; Hughes, Mike; Bradu, Adrian; Dobre, George; Podoleanu, Adrian G.

2010-02-01

23

Precision manufacture of optical disc master stampers  

E-print Network

industry term for the mold used to replicate polymer compact discs (CDs) in an injection molding device are not required, and a ceramic master is used directly as a stamper for injection molding. In the new process and photoresist, this nickel stamper can be used in an injection molding system to replicate polymer discs

24

High-resolution optical coherence tomography demonstration of membranes spanning optic disc pits and colobomas  

Microsoft Academic Search

Objectives:To demonstrate the features of optic disc pits and colobomas revealed by high-resolution optical coherence tomography (OCT) and their association with the development of maculopathy.Methods:Subjects with disc pits or colobomas and no other ocular history underwent full ophthalmic examinations including logMAR visual acuity and contrast sensitivity. Fundus photographs and high-resolution OCT images were obtained.Results:Seven patients were identified with optic disc

E Doyle; D Trivedi; P Good; R A Scott; G R Kirkby

2009-01-01

25

78 FR 55292 - Certain Optical Disc Drives, Components Thereof, and Products Containing the Same; Notice of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...COMMISSION [Docket No. 2977] Certain Optical Disc Drives, Components Thereof, and...received a complaint entitled Certain Optical Disc Drives, Components Thereof, and...Practice and Procedure filed on behalf of Optical Devices, LLC on September 3,...

2013-09-10

26

Recovering Data from Cracked Optical Discs using Hankel Iterative Learning Control  

Microsoft Academic Search

\\u000a Optical discs, including Compact Discs (CDs), Digital Versatile Discs (DVDs), and Blu-ray Discs (BDs), can get cracked during\\u000a storage and usage. Such cracks commonly lead to discontinuities in the data track, potentially preventing reading of the data\\u000a on the disc. The aim of the present paper is to improve tracking performance of the optical disc drive in the presence of

Maarten Steinbuch; Jeroen van de Wijdeven; Tom Oomen; Koos van Berkel; George Leenknegt

2009-01-01

27

Progranulin knockout accelerates intervertebral disc degeneration in aging mice.  

PubMed

Intervertebral disc (IVD) degeneration is a common degenerative disease, yet much is unknown about the mechanisms during its pathogenesis. Herein we investigated whether progranulin (PGRN), a chondroprotective growth factor, is associated with IVD degeneration. PGRN was detectable in both human and murine IVD. The levels of PGRN were upregulated in murine IVD tissue during aging process. Loss of PGRN resulted in an early onset of degenerative changes in the IVD tissue and altered expressions of the degeneration-associated molecules in the mouse IVD tissue. Moreover, PGRN knockout mice exhibited accelerated IVD matrix degeneration, abnormal bone formation and exaggerated bone resorption in vertebra with aging. The acceleration of IVD degeneration observed in PGRN null mice was probably due to the enhanced activation of NF-?B signaling and ?-catenin signaling. Taken together, PGRN may play a critical role in homeostasis of IVD, and may serve as a potential molecular target for prevention and treatment of disc degenerative diseases. PMID:25777988

Zhao, Yun-Peng; Tian, Qing-Yun; Liu, Ben; Cuellar, Jason; Richbourgh, Brendon; Jia, Tang-Hong; Liu, Chuan-Ju

2015-01-01

28

When do optic disc edema and peripheral neuropathy constitute poetry?  

PubMed

A patient with chronic, bilateral optic disc edema developed multiple systemic manifestations of POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes). A serum immunoelectrophoresis showed an abnormal serum IgG lambda protein, and urine immunoelectrophoresis revealed a monoclonal lambda protein plus an IgG lambda fragment. Bone survey and MRI scan revealed a sclerotic lesion of the first lumbar vertebra, and lymph node biopsy showed changes consistent with Castleman's disease. Thus, his optic disc edema was the presenting feature of the POEMS syndrome and osteosclerotic myeloma. PMID:2177227

Brazis, P W; Liesegang, T J; Bolling, J P; Kashii, S; Trachtman, M; Burde, R M

1990-01-01

29

Optic Disc Hemorrhage Is Related to Various Hemodynamic Findings by Disc Angiography  

PubMed Central

Background To investigate the hemodynamic characteristics of glaucoma eyes with disc hemorrhage (DH) by disc fluorescein angiography, and its relationship with glaucomatous changes of the optic disc and surrounding retinal nerve fiber layer (RNFL). Methods This study included 35 glaucoma eyes with DH who were followed up at least 5 years and had DH at presentation. Eyes were classified as eyes with DH at the border of localized RNFL defects and eyes with DH not related to localized RNFL defects. Prevalence of DH and location of the proximal border were recorded from disc photographs. Fluorescein angiography was performed 3 months after detecting the DH. Arm-retina time, arteriovenous transit time, disc filling time, choroidal filling time, and venous filling time were measured as retinal circulation parameters. The presence of disc filling defects and disc leaks were evaluated. Results There were 19 (54.3%) eyes with DH accompanying localized RNFL defects. The arm-retina time was prolonged in eyes with DH not related to RNFL defects (P = 0.044) and the arteriovenous transit time was prolonged in eyes with DH accompanying RNFL defects (P = 0.029). Among eyes with DH accompanying RNFL defects, 11 (57.9%) had vessel filling defects or delayed filling indicating blood flow stasis at the cup margin proximal to where DH occurred. Eyes with DH not related to RNFL defects did not show vessel filling defects or delayed filling. Conclusions and Relevance Eyes with DH related to RNFL defects showed prolonged arteriovenous transit time and had frequent vessel filling defects or delayed filling indicating blood flow stasis and thrombus formation at the site DH occurred. These findings suggest that vascular and hemodynamic changes due to glaucomatous structural changes cause DH in relation to localized RNFL defects. PMID:25879852

Park, Hae Young Lopilly; Jeong, Hyun Jin; Kim, Yoon Hee; Park, Chan Kee

2015-01-01

30

Vertical cup/disc ratio in relation to optic disc size: its value in the assessment of the glaucoma suspect  

PubMed Central

AIMS—The vertical cup/disc ratio (CDR) has long been used in the assessment of the glaucoma suspect, though the wide range of CDR values in the normal population limits its use. Cup size is related physiologically to disc size and pathologically to glaucomatous damage. Disc size can be measured at the slit lamp as the vertical disc diameter (DD). The ability of the CDR, in relation to DD, to identify glaucomatous optic discs was investigated.?METHODS—88 normal, 53 early glaucoma, and 59 ocular hypertensive subjects underwent stereoscopic optic disc photography and clinical biometry. Photographs were analysed in a masked fashion by computer assisted planimetry. The relation between vertical cup diameter and DD was explored by linear regression, and expressed in terms of CDR. The upper limit of normal was defined by the 95% prediction intervals of this regression (method 1) and by the upper 97.5 percentile for CDR (method 2). The sensitivity and specificity of CDR to identify an optic disc as glaucomatous was tested with these disc size dependent and disc size independent cut offs in small, medium, and large discs.?RESULTS—The CDR was related to DD by the equation CDR = (?1.31 + (1.194 × DD))/DD. The sensitivity in small, medium, and large discs was 80%, 60%, and 38% respectively for method 1 and 33%, 67%, and 63% respectively for method 2. Specificity was 98.9% (method 1) and 97.7% (method 2).?CONCLUSIONS—The CDR, relative to disc size, is useful clinically, especially to assist in identifying small glaucomatous discs.?? Keywords: cup/disc ratio; glaucoma; imaging PMID:9924296

Garway-Heath, D.; Ruben, S.; Viswanathan, A.; Hitchings, R.

1998-01-01

31

Optical channel modeling for InSb-based super-resolution disc storage  

Microsoft Academic Search

A complete optical channel model of a super-resolution optical disc system is developed that includes not only the optical pick-up but also the super-resolution disc, using InSb for the mask layer. This is a candidate technology for a next generation of optical discs after the Blu-ray Disc. Model parameters have been derived to match former static experiments. The model is

Dietmar Hepper; Deutsche Thomson

2011-01-01

32

Lamina Cribrosa Defects and Optic Disc Morphology in Primary Open Angle Glaucoma with High Myopia  

PubMed Central

Purpose To investigate whether lamina cribrosa (LC) defects are associated with optic disc morphology in primary open angle glaucoma (POAG) eyes with high myopia. Methods A total of 129 POAG patients and 55 age-matched control subjects with high myopia were evaluated. Three-dimensional scan images obtained by swept source optical coherence tomography were used to detect LC defects. Radial B-scans and infrared images obtained by spectral domain optical coherence tomography were used to measure ?-peripapillary atrophy (PPA) lengths with and without Bruch's membrane (BM) (temporal, nasal, superior, and inferior), tilt angle (vertical and horizontal), and disc diameter (transverse and longitudinal). Peripapillary intrachoroidal cavitations (PICCs), disc area, ovality index, and cyclotorsion of the optic disc were analyzed as well. Results LC defects were found in 70 of 129 (54.2%) POAG eyes and 1 of 55 (1.8%) control eyes (P<0.001). Age, sex, spherical equivalent, axial length, intraocular pressure, and central corneal thickness were not significantly different among POAG eyes with LC defects, POAG eyes without LC defects, and control eyes. Temporal PPA lengths without BM in all three groups correlated significantly with vertical and horizontal tilt angles, although no PPA length with BM correlated significantly with any tilt angle. PICCs were detected more frequently in POAG eyes with LC defects than those without LC defects (P?=?0.01) and control eyes (P?=?0.02). POAG eyes with LC defects showed a smaller ovality index (P?=?0.004), longer temporal PPA without BM (P<0.001), and larger vertical/horizontal tilt angles (vertical, P<0.001; horizontal, P?=?0.01), and transverse diameter (P?=?0.01). In multivariate analysis for the presence of LC defects, presence of POAG (P<0.001) and vertical tilt angle (P<0.001) were identified as significant. Conclusions The presence of LC defects was associated with myopic optic disc morphology in POAG eyes with high myopia. PMID:25531656

Kimura, Yugo; Akagi, Tadamichi; Hangai, Masanori; Takayama, Kohei; Hasegawa, Tomoko; Suda, Kenji; Yoshikawa, Munemitsu; Yamada, Hiroshi; Nakanishi, Hideo; Unoki, Noriyuki; Ikeda, Hanako Ohashi; Yoshimura, Nagahisa

2014-01-01

33

[Optic disc drusen - current diagnostic possibilities].  

PubMed

Authors present the findings of two patients with optic nerve drusen, and an overview of current examination techniques in the diagnostics of optic nerve drusen including ultrasound examination, fundus photography, florescein angiography, computerized perimetry, auto-florescence fundus examination, examination of the nerve fibre layer using optical coherence tomography (OCT) or nerve fibres layer analyzer (GDx). In the first case, the patient was recommended to be supervised without any therapy. The second patient with regard to perimeter finding, loss of nerve fibre layer and increase of the intraocular pressure was prescribed local anti-glaucoma therapy. PMID:24862373

Ziak, P; Jarabáková, K; Koyšová, M

2014-02-01

34

Optic disc topography of normal tension glaucoma patients in Malaysia.  

PubMed

There are limited data in the literature on the optic disc topography in normal tension glaucoma (NTG) patients in Asian countries, especially in Southeast Asia. This study is aimed at comparing optic disc topography in NTG patients and a control group in Malaysia, and we discuss the literature on NTG studies in other Asian populations. A comparative cross-sectional study was conducted in two hospitals with glaucoma services in Malaysia from November 2010 to February 2012. A total of 109 eyes of 109 Malay patients were included in this study: 32 NTG patients and 77 subjects in the control group. All participants underwent a thorough ocular examination, including visual acuity, subjective refraction, anterior segment and fundus examinations, Humphrey visual field 24-2, intraocular pressure measurement, gonioscopy examination and fundus photography. Optic disc topography was assessed using the Heidelberg Retinal Tomograph III by an identified masked investigator in each hospital. NTG patients had a notably larger disc area (2.65 (0.41) vs 2.19 (0.43) mm(2), respectively), larger cupping (1.54 (0.43) vs 0.63 (0.40) mm(2), respectively), smaller retinal rim areas (1.12 (0.41) vs 1.56 (0.33) mm(2), respectively), higher cup volume (0.47 (0.28) vs 0.11 (0.19) mm(3), respectively), reduced rim volume (0.23 (0.13) vs 0.41 (0.16) mm(3), respectively), higher cup to disc area ratio (0.58 (0.14) vs 0.27 (0.15), respectively), higher linear cup to disc ratio (0.76 (0.09) vs 0.49 (0.17) mm(2), respectively), higher mean cup depth (0.37 (0.09) vs 0.22 (0.09) mm, respectively), higher maximum cup depth (0.77 (0.16) vs 0.59 (0.20) mm, respectively), higher mean of cup shape measure (-0.04 (0.06) vs -0.16 (0.07), respectively), and thinner mean retinal nerve fibre layer thickness (0.15 (0.15) vs 0.24 (0.07) mm, respectively) compared to the control group (p<0.05). In conclusion, most of the optic disc parameters were significantly different in NTG patients compared to healthy individuals in Malaysia. Our findings are comparable to those reported in NTG studies in other Asian countries. PMID:24145263

Adlina, Abdul Rahim; Shatriah, Ismail; Liza Sharmini, Ahmad Tajudin; Ahmad, Mt Saad

2013-08-01

35

Measurement of the Optic Disc Vertical Tilt Angle With Spectral-Domain Optical Coherence Tomography and  

E-print Network

Measurement of the Optic Disc Vertical Tilt Angle With Spectral-Domain Optical Coherence Tomography, AND KOUROS NOURI-MAHDAVI PURPOSE: To report a novel method for measuring the vertical tilt angle-domain optical coherence tomography (SDOCT). The vertical tilt angle was measured on high-resolution cross

Levine, Alex J.

36

Chondroadherin fragmentation mediated by the protease HTRA1 distinguishes human intervertebral disc degeneration from normal aging.  

PubMed

Chondroadherin, a member of the leucine-rich repeat family, has previously been demonstrated to be fragmented in some juveniles with idiopathic scoliosis. This observation led us to investigate adults with disc degeneration. Immunoblotting analysis demonstrated that non-degenerate discs from three different age groups show no chondroadherin fragmentation. Furthermore, the chondroadherin fragments in adult degenerate disc and the juvenile scoliotic disc were compared via immunoblot analysis and appeared to have a similar size. We then investigated whether or not chondroadherin fragmentation increases with the severity of disc degeneration. Three different samples with different severities were chosen from the same disc, and chondroadherin fragmentation was found to be more abundant with increasing severity of degeneration. This observation led us to the creation of a neoepitope antibody to the cleavage site observed. We then observed that the cleavage site in adult degenerate discs and juvenile scoliotic discs was identical as confirmed by the neoepitope antibody. Consequently, investigation of the protease capable of cleaving chondroadherin at this site was necessary. In vitro digests of disc tissue demonstrated that ADAMTS-4 and -5; cathepsins K, B, and L; and MMP-3, -7, -12, and -13 were incapable of cleavage of chondroadherin at this site and that HTRA1 was indeed the only protease capable. Furthermore, increased protein levels of the processed form of HTRA1 were demonstrated in degenerate disc tissues via immunoblotting. The results suggest that chondroadherin fragmentation can be used as a biomarker to distinguish the processes of disc degeneration from normal aging. PMID:23673665

Akhatib, Bashar; Onnerfjord, Patrik; Gawri, Rahul; Ouellet, Jean; Jarzem, Peter; Heinegård, Dick; Mort, John; Roughley, Peter; Haglund, Lisbet

2013-06-28

37

Bilateral optic disc oedema and associated optic neuropathy in the setting of FOLFOX chemotherapy  

PubMed Central

Background To report a case of bilateral optic disc oedema and associated optic neuropathy in the setting of FOLFOX chemotherapy. Case presentation A case of a 57-year-old male being treated with FOLFOX chemotherapy for stage 3B colorectal cancer, who developed bilateral optic disc oedema and associated left sided optic neuropathy is described. The patient presented following cycles 7, 8 and 9 of chemotherapy with a history of bilateral simultaneous intermittent inferior altitudinal field defects. These episodes progressed to bilateral optic nerve oedema and a subsequent left sided optic neuropathy. The patient’s symptoms and oedema regressed with discontinuation of chemotherapy. Conclusion This is the first report suggesting a vasospastic role of 5-fluoruracil in 5-FU associated optic neuropathy. It highlights that 5-FU may have the potential to cause arterial vasospasm outside the cardiac vasculature, resulting in end-organ optic nerve ischaemia. PMID:23926927

2013-01-01

38

78 FR 64009 - Certain Optical Disc Drives, Components Thereof, and Products Containing the Same; Institution of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Investigation No. 337-TA-897] Certain Optical Disc Drives, Components Thereof, and...amended, 19 U.S.C. 1337, on behalf of Optical Devices, LLC of Peterborough, New Hampshire...United States after importation of certain optical disc drives, components thereof,...

2013-10-25

39

Cup-To-Disc Ratio Of The Optic Disc By Image Analysis To Assist Diagnosis Of Glaucoma Risk And Evolution  

NASA Astrophysics Data System (ADS)

This work builds an image analysis algorithm to give assistance in the cup to disc ratio estimation of glaucomatous eyes. Often the contours of both the optic cup and disc are faint and intersected by entangled veins that make it difficult to draw their silhouettes. The algorithm, which takes into account the viewing conditions of the specialist, is based on the information of color, the color differences between neighbor pixels and the geometry of the areas involved.

Valencia, Edison; Millán, María S.; Kotynski, Rafal

2006-10-01

40

Optic nerve axons and acquired alterations in the appearance of the optic disc.  

PubMed Central

The pathophysiologic events in optic nerve axons have recently been recognized as crucial to an understanding of clinically significant acquired alterations in the ophthalmoscopic appearance of the optic disc. Stasis and related abnormalities of axonal transport appear to explain most aspects of optic nerve head swelling, including optic disc drusen and retinal cottonwool spots. Loss of axoplasm and axonal death can be invoked to interpret optic disc pallor, thinning and narrowing of rim tissue, changes in the size and outline of the optic cup, laminar dots, atrophy of the retinal nerve fiber layer, and acquired demyelination and myelination of the retinal nerve fiber layer. It is speculated that the axons may also play a role in the mechanical support of the lamina cribrosa in resisting the pressure gradient across the pars scleralis of the optic nerve head. Axons and their associated glial cells may be involved in those cases where "reversibility" of cupping of the optic disc has been reported. The structure, physiology, and experimental pathologic findings of the optic nerve head have been reviewed. Many aspects concerning the final anatomic appearance of the optic nerve head have been explained. However, many questions remain concerning the intermediate mechanisms by which increased intracranial pressure retards the various components of axonal transport in papilledema and by which increased IOP causes axonal loss in glaucoma. Investigation of the molecular biology of axonal constituents and their responses to abnormalities in their physical and chemical milieu could extend our understanding of the events that result from mechanical compression and local ischemia. Moreover, we have identified a need to further explore the role of axons in the pathophysiology of optic disc cupping. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 11 FIGURE 12 FIGURE 13 PMID:6203209

Wirtschafter, J D

1983-01-01

41

Liquid immersion deep-UV optical disc mastering for high data capacity ROM discs  

Microsoft Academic Search

In this paper we describe the liquid immersion mastering technique and its application to the mastering of ROM discs for the Blu-ray Disc system and for ROM discs with considerably higher data densities. Replicated 25GB BD-ROM discs were evaluated using a standard blue test player (lambda=405nm, NA=0.85). A bottom jitter value with limit equalizer of less than 5% was measured.

Jaap H. M. Neijzen; Erwin R. Meinders; Marius I. Boamfa; Dianyong Chen

2005-01-01

42

Automatic optic disc segmentation based on image brightness and contrast  

NASA Astrophysics Data System (ADS)

Untreated glaucoma leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness. As glaucoma often produces additional pathological cupping of the optic disc (OD), cupdisc- ratio is one measure that is widely used for glaucoma diagnosis. This paper presents an OD localization method that automatically segments the OD and so can be applied for the cup-disc-ratio based glaucoma diagnosis. The proposed OD segmentation method is based on the observations that the OD is normally much brighter and at the same time have a smoother texture characteristics compared with other regions within retinal images. Given a retinal image we first capture the ODs smooth texture characteristic by a contrast image that is constructed based on the local maximum and minimum pixel lightness within a small neighborhood window. The centre of the OD can then be determined according to the density of the candidate OD pixels that are detected by retinal image pixels of the lowest contrast. After that, an OD region is approximately determined by a pair of morphological operations and the OD boundary is finally determined by an ellipse that is fitted by the convex hull of the detected OD region. Experiments over 71 retinal images of different qualities show that the OD region overlapping reaches up to 90.37% according to the OD boundary ellipses determined by our proposed method and the one manually plotted by an ophthalmologist.

Lu, Shijian; Liu, Jiang; Lim, Joo Hwee; Zhang, Zhuo; Tan, Ngan Meng; Wong, Wing Kee; Li, Huiqi; Wong, Tien Yin

2010-03-01

43

Twenty-Layer Optical Disc Fabricated by Web Coating and Lamination  

NASA Astrophysics Data System (ADS)

We developed a new fabrication method for multilayer optical discs for the high-throughput production of such discs. We used web coating and lamination to prepare a stacked unit. The stacked unit was a layered structure consisting of a recording layer, a UV resin layer, a recording layer, and a pressure-sensitive adhesive layer. We obtained a 20-layer disc simply by laminating the stacked units 10 times. The transmittance of the 20 recording layers was 87% owing to the high transparency of the two-photon recording material. A scanning electron microscopy (SEM) image of the disc showed a clear multilayer structure. The recording layers of the disc were recorded using a pulse laser without interlayer cross write. The thickness variation of the transparent part of the disc was within +/-2 µm, and the tilt angles of the disc satisfied the Blu-ray disc (BD) specifications.

Mikami, Tatsuo; Mochizuki, Hidehiro; Sasaki, Toshio; Kitahara, Toshiyuki; Tsuyama, Hiroaki; Inoue, Kenichirou; Ito, Masaharu

2013-09-01

44

Double-Vitrectomy for Optic Disc Pit Maculopathy  

PubMed Central

Background The origin of the fluid and precise pathophysiology of optic pit maculopathy remain unclear. It has been suggested that submacular fluid originates either from vitreous or cerebrospinal fluid. We report a case of optic pit maculopathy which was unsuccessfully treated with vitrectomy and internal limiting membrane (ILM) peeling, and subsequently resolved with revision of vitrectomy and gas tamponade. Methods We report a case of optic disc pit maculopathy, well documented by spectral- domain optical coherence tomography, before and after pars plana vitrectomy with ILM peeling, and its revision with gas tamponade. Results After ILM peeling, there was no improvement either in visual acuity or in the tomographic aspect of the retina. A revision of the surgery was then needed and gas tamponade was performed, which resulted in a complete resolution of the optic pit maculopathy. Conclusion The absence of improvement after ILM peeling during the first surgical procedure, accompanied by resolution of the clinical picture with gas tamponade during the second surgical procedure, sustained the hypothesis of a subarachnoidal origin of the fluid. PMID:22679433

Pichi, Francesco; Morara, Mariachiara; Veronese, Chiara; Lembo, Andrea; Vitale, Lucia; Ciardella, Antonio P.; Nucci, Paolo

2012-01-01

45

Automatic Optic Disc Detection in OCT Slices via Low-Rank Reconstruction.  

PubMed

Optic disc measurements provide useful diagnostic information as they have correlations with certain eye diseases. In this paper, we provide an automatic method for detecting the optic disc in a single OCT slice. Our method is developed from the observation that the retinal pigment epithelium (RPE) which bounds the optic disc has a low-rank appearance structure that differs from areas within the disc. To detect the disc, our method acquires from the OCT image an RPE appearance model that is specific to the patient and imaging conditions, by learning a lowrank dictionary from image areas known to be part of the RPE according to priors on ocular anatomy. The edge of the RPE, where the optic disc is located, is then found by traversing the retinal layer containing the RPE, reconstructing local appearance with the low-rank model, and detecting the point at which appearance starts to deviate (i.e., increased reconstruction error). To aid in this detection, we also introduce a geometrical constraint called the distance bias that accounts for the smooth shape of the RPE. Experiments demonstrate that our method outperforms other OCT techniques in localizing the optic disc and estimating disc width. Moreover, we also show the potential usage of our method on optic disc area detection in 3D OCT volumes. PMID:25438300

Fu, Huazhu; Xu, Dong; Lin, Stephen; Wong, Wing Kee; Liu, Jiang

2014-11-26

46

Parapapillary atrophy and optic disc region assessment (PANDORA): retinal imaging tool for assessment of the optic disc and parapapillary atrophy  

NASA Astrophysics Data System (ADS)

We describe a computer-aided measuring tool, named parapapillary atrophy and optic disc region assessment (PANDORA), for automated detection and quantification of both the parapapillary atrophy (PPA) and the optic disc (OD) regions in two-dimensional color retinal fundus images. The OD region is segmented using a combination of edge detection and ellipse fitting methods. The PPA region is identified by the presence of bright pixels in the temporal zone of the OD, and it is segmented using a sequence of techniques, including a modified Chan-Vese approach, thresholding, scanning filter, and multiseed region growing. PANDORA has been tested with 133 color retinal images (82 with PPA; 51 without PPA) drawn randomly from the Lothian Birth Cohort (LBC) database, together with a "ground truth" estimate from an ophthalmologist. The PPA detection rate is 89.47% with a sensitivity of 0.83 and a specificity of 1. The mean accuracy in defining the OD region is 81.31% (SD=10.45) when PPA is present and 95.32% (SD=4.36) when PPA is absent. The mean accuracy in defining the PPA region is 73.57% (SD=11.62). PANDORA demonstrates for the first time how to quantify the OD and PPA regions using two-dimensional fundus images, enabling ophthalmologists to study ocular diseases related to PPA using a standard fundus camera.

Lu, Cheng-Kai; Tang, Tong Boon; Laude, Augustinus; Dhillon, Baljean; Murray, Alan F.

2012-10-01

47

Fast localization of optic disc and fovea in retinal images for eye disease screening  

NASA Astrophysics Data System (ADS)

Optic disc (OD) and fovea locations are two important anatomical landmarks in automated analysis of retinal disease in color fundus photographs. This paper presents a new, fast, fully automatic optic disc and fovea localization algorithm developed for diabetic retinopathy (DR) screening. The optic disc localization methodology comprises of two steps. First, the OD location is identified using template matching and directional matched filter. To reduce false positives due to bright areas of pathology, we exploit vessel characteristics inside the optic disc. The location of the fovea is estimated as the point of lowest matched filter response within a search area determined by the optic disc location. Second, optic disc segmentation is performed. Based on the detected optic disc location, a fast hybrid level-set algorithm which combines the region information and edge gradient to drive the curve evolution is used to segment the optic disc boundary. Extensive evaluation was performed on 1200 images (Messidor) composed of 540 images of healthy retinas, 431 images with DR but no risk of macular edema (ME), and 229 images with DR and risk of ME. The OD location methodology obtained 98.3% success rate, while fovea location achieved 95% success rate. The average mean absolute distance (MAD) between the OD segmentation algorithm and "gold standard" is 10.5% of estimated OD radius. Qualitatively, 97% of the images achieved Excellent to Fair performance for OD segmentation. The segmentation algorithm performs well even on blurred images.

Yu, H.; Barriga, S.; Agurto, C.; Echegaray, S.; Pattichis, M.; Zamora, G.; Bauman, W.; Soliz, P.

2011-03-01

48

Optic disc edema in non-arteritic anterior ischemic optic neuropathy  

Microsoft Academic Search

We investigated the clinical characteristics, time to resolution and the factors that influence it, and evolutionary pattern\\u000a of optic disc edema (ODE) in non-arteritic anterior ischemic optic neuropathy (NA-AION). Our study was conducted in 591 consecutive\\u000a patients (749 eyes) with NA-AION who fulfilled our inclusion criteria. On their first visit to our clinic, all patients had\\u000a a detailed ophthalmic and

Sohan Singh Hayreh; M. Bridget Zimmerman

2007-01-01

49

Liquid immersion deep-UV optical disc mastering for high data capacity ROM discs  

NASA Astrophysics Data System (ADS)

In this paper we describe the liquid immersion mastering technique and its application to the mastering of ROM discs for the Blu-ray Disc system and for ROM discs with considerably higher data densities. Replicated 25GB BD-ROM discs were evaluated using a standard blue test player (?=405nm, NA=0.85). A bottom jitter value with limit equalizer of less than 5% was measured. Also the values of asymmetry, normalized push pull and symbol error rate were well within the Blu-ray Disc format specification, offering a large process window. Full-format BD-ROM test discs with high definition video content were mastered and their successful read-back was demonstrated. In addition we show that liquid immersion mastering can successfully be applied for mastering of considerably higher densities. Measurements on replicated discs up to data densities above 40GB per layer are discussed. The present results demonstrate that liquid immersion mastering is a proven technology for the mass-production of high data capacity ROM discs.

Neijzen, Jaap H. M.; Meinders, Erwin R.; Boamfa, Marius I.; Chen, Dianyong

2005-09-01

50

Aquaporin-1 and Aquaporin-3 Expressions in the Intervertebral Disc of Rats with Aging  

PubMed Central

Objective: The intervertebral disc (IVD) undergoes biochemical and morphologic degenerative changes during the process of aging. Aquaporins (AQPs) are a family of water channel proteins that facilitate water and small solute movement in tissues and may have a potential role in the aging degeneration of IVDs. One of the important problems in understanding disc degeneration is to find cellular molecules which contribute to the pathogenesis of IVDs. XThe aim of this study was to demonstrate the expression of aquaporin 1 and 3 in nucleus pulposus (NP), annulus fibrosus (AF) cells of rat lumbar intervertebral discs from both young and aged animals using immunohistochemistry. Material and Methods: Twenty Wistar-albino rats were included in the study. The rats were separated into two groups: 2-month-old rats (n=10) as the young group, 18-month-old rats (n=10) as the old group. The intervertebral disc tissues obtained from the lumbar spine (L1–L4, 4 discs) were used for immunohistochemical staining of AQP-1 and 3. Results: This study demonstrated that AQP-1 and AQP-3 immunoreactivity significantly decreased in NP and AF of aged rats compared to the young rats. Conclusion: We suggest that AQP-1 and 3 may contribute to the age related degeneration of the intervertebral disc. PMID:25207032

Ta?, Ufuk; Çayl?, Sevil; ?nan?r, Ahmet; Özyurt, Birsen; Ocakl?, Seda; Karaca, Zafer ?smail; Sars?lmaz, Mustafa

2012-01-01

51

Compact design for a unitary photo detector and single-path combo optical pickup head for Blu-ray disc, digital versatile disc and compact disc systems  

NASA Astrophysics Data System (ADS)

We present a compact design for a unitary photo detector and single-path combination optical pickup head (OPH) which can be used for Blu-ray Disc, digital versatile disc and compact disc systems. The number of components in the OPH design can be reduced by focusing three discrete wavelength laser beams on the photo detector. The three laser diode chips and a photo detector can be encapsulated within an integrated optical unit (IOU), which is then combined with a compensator and rhomboid beam-splitter prism. The blazed holographic optical elements (HOEs) are designed for concentrating the diffracted light power to the 0th-order and the 1st-order to improve the round-trip efficiency. The simulation results, including the S-curve and optical efficiency, are compared for this combo-OPH with three IOUs. The optical efficiency of the proposed OPH for BD/DVD/CD systems as detected by the photo detector are 5.545%, 3.889%, and 3.517%, respectively. Our design results show that the combo-OPH with one IOU is better than the combo-OPH with three IOUs.

Sun, Wen-Shing; Lin, Yan-Nan; Tien, Chuen-Lin; Tsuei, Chih-Hsuan; Kuo, Chien-Cheng; Chang, Jenq-Yang

2012-09-01

52

Polarization-Free Blu-ray Disc/Digital Versatile Disc Compatible Optical Pick-up  

NASA Astrophysics Data System (ADS)

We have developed Blu-ray disc (BD)/digital versatile disc (DVD) compatible technology employing a polarization-free wavefront correction element. The polarization-free wavefront correction elements have high diffraction efficiencies for both BD and DVD. Also, this element has a large decentering tolerance for the objective lens. The effectiveness of this element was confirmed by examining wavefront aberrations for DVD and readout signal waveforms for both BD and DVD.

Saito, Ryo; Ito, Fumihiko; Yokochi, Yoshinari; Saito, Toshiya; Ohira, Takuji; Sato, Hidetoshi; Itonaga, Makoto

2004-07-01

53

Polarization-Free Blu-ray Disc\\/Digital Versatile Disc Compatible Optical Pick-up  

Microsoft Academic Search

We have developed Blu-ray disc (BD)\\/digital versatile disc (DVD) compatible technology employing a polarization-free wavefront correction element. The polarization-free wavefront correction elements have high diffraction efficiencies for both BD and DVD. Also, this element has a large decentering tolerance for the objective lens. The effectiveness of this element was confirmed by examining wavefront aberrations for DVD and readout signal waveforms

Ryo Saito; Fumihiko Ito; Yoshinari Yokochi; Toshiya Saito; Takuji Ohira; Hidetoshi Sato; Makoto Itonaga

2004-01-01

54

Biostereometrics In Ophthalmology For Measurement Of The Optic Disc Cup In Glaucoma  

NASA Astrophysics Data System (ADS)

Glaucoma is a disease characterized by increased ocular pressure with optic nerve atrophy and loss of visual field or side vision which eventually leads to blindness. The surface of the portion of the optic nerve within the eye, the optic disc, becomes depressed and its contours are altered. The optic disc becomes more cupped with increasing progress of the disease. For measurement of the cup, retinal cameras can provide simultaneous stereo photographs of the optic disc taken through the pupil. However, the photographs have to be obtained at a narrow angle due to the limit of the size of the dilated pupil. Our studies of the geometry of the stereo photographs show a greater error in depth compared to horizontal dimensions because of this biological limit. Similarly, data for the optimal conditions for photography of the optic disc, including aperture size and magnification have been obtained. Since the changes in the optic disc can progress with increase of the desease, photogrammetric techniques for measuring relative changes in the dimensions of the cup have been developed. Both subsequent and initial photographs are measured after being similarly oriented in space. The photogrammetric measurement of changes in the optic disc cup in glaucoma has potential as a useful technique which can have wide clinical application.

Schwartz, Bernard; Takamoto, Takenori

1980-07-01

55

Biostereometrics in Ophthalmology: Topographic Analysis of the Optic Disc Cup in Glaucoma  

NASA Astrophysics Data System (ADS)

Glaucoma is a disease characterized by increased ocular pressure with optic nerve atrophy and loss of visual field, or side vision, which eventually leads to blindness. The optic disc becomes more cupped with increasing progress of the disease. We have devised a system for the use of the Donaldson simultaneous stereophotographic fundus camera to obtain optimal reproducibility and sensitivity of measurements from optic disc stereophotographs. Stereomodel deformations caused by eye-to-camera optical variables (photographic magnification, working distance, relative orientation between the camera optical axis and the optic disc, and position of the optic disc image in the film frame) were evaluated. We developed an analytical correction method for stereomodel deformations and evaluated the impact on measurement of optic disc cupping. We have evaluated the reproducibility of new techniques for measurement of cup parameters such as volume, depth, and area of the cup relative to the disc area; slope of the cup floor, wall, and rim; and cup shape using volume profiles in which contour areas were plotted of the cup depth from the top to the bottom.

Takamoto, Takenori; Schwartz, Bernard

1986-07-01

56

Retinal imaging tool for assessment of the parapapillary atrophy and the optic disc   

E-print Network

Ophthalmic diseases such as glaucoma are associated with progressive changes in the structure of the optic disc (OD) and parapapillary atrophy (PPA). These structural changes may therefore have relevance to other systemic ...

Lu, Cheng-Kai

2012-11-29

57

Detection of optic disc glaucoma damages using image analysis and artificial neural net  

NASA Astrophysics Data System (ADS)

A new method of the optic disc glaucomatous damage detection and the diagnosis determination is presented in this paper. This method is based on the measurement of the relative size of the representative pallor area on the color digital optic disc image and its evaluation using a statistical method and computer-simulated artificial neural net. Finally, the dependence of the relative pallor area size of the glaucomatous eye and glaucomatous visual field changes is studied.

Pluhacek, Frantisek; Pospisil, Jaroslav; Kubena, Tomas; Maresova, Klara

2003-10-01

58

Increasing the storage density for a 4th-Generation Optical Disc  

Microsoft Academic Search

While CD, DVD and Blu-ray disc (BD) are on the market, attempts are being made by industry and research facilities to further increase the storage density for the next or 4th generation of optical storage. The objective is an increase by a factor of 3...4 compared to BD. The European funded project MobileDrive\\/4GOOD (4th-Generation, omni-purpose optical disc-system) chose the super-resolution

Dietmar Hepper; Xiao-Ming Chen; Stephan Knappmann; Gaël Pilard; Hartmut Richter; Oliver Theis; M. Wuttig

2009-01-01

59

Dissecting simulated disc galaxies - I. The structure of mono-age populations  

NASA Astrophysics Data System (ADS)

We study seven simulated disc galaxies, three with a quiescent merger history, and four with mergers in their last 9 Gyr of evolution. We compare their structure at z = 0 by decomposing them into `mono-age populations' (MAPs) of stars within 500 Myr age bins. All studied galaxies undergo a phase of merging activity at high redshift, so that stars older than 9 Gyr are found in a centrally concentrated component, while younger stars are mostly found in discs. We find that most MAPs have simple exponential radial and vertical density profiles, with a scaleheight that typically increases with age. Because a large range of merger histories can create populations with simple structures, this suggests that the simplicity of the structure of mono-abundance populations observed in the Milky Way by Bovy et al. is not necessarily a direct indicator of a quiescent history for the Milky Way. Similarly, the anticorrelation between scalelength and scaleheight does not necessarily imply a merger-free history. However, mergers produce discontinuities between thin and thick disc components, and jumps in the age-velocity relation. The absence of a structural discontinuity between thin and thick disc observed in the Milky Way would seem to be a good indicator that no merger with a mass ratio larger than 1:15-1:10 occurred in the last 9 Gyr. Mergers at higher redshift might nevertheless be necessary to produce the thickest, hottest components of the Milky Way's disc.

Martig, Marie; Minchev, Ivan; Flynn, Chris

2014-08-01

60

Recording Characteristics of 10-Layer Recordable Optical Disc and a Prospect for Over 500 Gbyte Recording  

NASA Astrophysics Data System (ADS)

A 10-layer recordable optical disc with an inorganic recording material, Bi-Ge-O, was fabricated and the recording characteristics were measured using a Blu-ray Disc-based apparatus with a wavelength of 405 nm and a numerical aperture of 0.85. Practical signal quality was obtained from all the layers at densities of 25 and 32 Gbyte per layer. A 16-layer recordable optical disc was also fabricated and measured. Practical signal quality was also obtained from both the 1st layer and the 16th layer.

Kikukawa, Takashi; Inoue, Motohiro; Mishima, Koji; Ushida, Tomoki

2010-08-01

61

Assessment of the Optic Disc Morphology Using Spectral-Domain Optical Coherence Tomography and Scanning Laser Ophthalmoscopy  

PubMed Central

Objective. To compare the equivalent optic nerve head (OHN) parameters obtained with confocal scanning laser ophthalmoscopy (HRT3) and spectral-domain optical coherence tomography (OCT) in healthy and glaucoma patients. Methods. One hundred and eighty-two consecutive healthy subjects and 156 patients with open-angle glaucoma were divided into 2 groups according to intraocular pressure and visual field outcomes. All participants underwent imaging of the ONH with the HRT3 and the Cirrus OCT. The ONH parameters and the receiver operating characteristic (ROC) curves were compared between both groups. Results. Mean age did not differ between the normal and glaucoma groups (59.55 ± 9.7 years and 61.05 ± 9.4 years, resp.; P = 0.15). Rim area, average cup-to-disc (C/D) ratio, vertical C/D ratio, and cup volume were different between both instruments (P < 0.001). All equivalent ONH parameters, except disc area, were different between both groups (P < 0.001). The best areas under the ROC curve were observed for vertical C/D ratio (0.980 for OCT and 0.942 for HRT3; P = 0.11). Sensitivities at 95% fixed-specificities of OCT parameters were higher than those of HRT3. Conclusions. Equivalent ONH parameters of Cirrus OCT and HRT3 are different and cannot be used interchangeably. ONH parameters measured with OCT yielded a slightly better diagnostic performance. PMID:25110668

Calvo, Pilar; Ferreras, Antonio; Abadia, Beatriz; Ara, Mirian; Figus, Michele; Pablo, Luis E.; Frezzotti, Paolo

2014-01-01

62

Bit-Error-Rate-Based Evaluation of Energy-Gap-Induced Super-Resolution Read-Only-Memory Disc in Blu-ray Disc Optics  

Microsoft Academic Search

Bit error rate (bER) of an energy-gap-induced super-resolution (EG-SR) read-only-memory (ROM) disc with a zinc oxide (ZnO) film was measured in Blu-ray Disc (BD) optics by the partial response maximum likelihood (PRML) detection method. The experimental capacity was 40 GB in a single-layered 120 mm disc, which was about 1.6 times as high as the commercially available BD with 25

Hideharu Tajima; Hirohisa Yamada; Tetsuya Hayashi; Masaki Yamamoto; Yasuhiro Harada; Go Mori; Jun Akiyama; Shigemi Maeda; Yoshiteru Murakami; Akira Takahashi

2008-01-01

63

Triplet collimator lens design of blu-ray disc optical pick-up  

Microsoft Academic Search

During the design process of Blu-ray Disc Optical Pick-Up (BD OPU), the optical system design plays a significant role, and the collimator lens design is especially important. According to the PW optical design formulas, this paper calculates the initial parameters of collimator lens. It chooses the triplet type collimator lens instead of aspheric lens to design in order to reduce

Lihua Li; Junhui Lu; Longfa Pan; Jianshe Ma

2008-01-01

64

In Vivo Adaptive Optics Imaging of the Temporal Raphe and Its Relationship to the Optic Disc and Fovea in the Human Retina  

PubMed Central

Purpose. To investigate the anatomy of the temporal raphe and its angular relationship to the optic disc and fovea in the human retina in vivo. Methods. Adaptive optics scanning laser ophthalmoscope (AOSLO) was used to image the temporal raphe in 11 young subjects. The raphe's angle relative to a horizontal line and the raphe-fovea-disc angle (angle between the raphe and the line connecting the disc and fovea center) were determined. In addition, to investigate the impact of aging on the raphe, we imaged the raphe at 9° eccentricity in 10 additional older healthy subjects and compared the raphe's anatomy between the two age groups. Results. The raphe's in vivo appearance was generally in agreement with major findings of ex vivo studies. The raphe angle was ?1.67° ± 4.8°, with the ranges from ?9° to 6°. It was related to the angle of the foveal depression relative to the disc. The raphe-fovea-disc angle was 170.3° ± 3.6°. The raphe gap, defined as the averaged distance between superior and inferior bundles, was significantly larger in the older subjects than in younger subjects (230.83 ± 113.22 ?m vs. 1.93 ± 68.73 ?m, P < 0.0001). Conclusions. The angle of the raphe in the study was not consistent with classic raphe models. While the angle showed relatively large individual variability, there seems to be a systematic relation between the disc, fovea, and raphe. It may be useful for individualizing retinal measurement strategies with regard to perimetry. PMID:25146991

Huang, Gang; Gast, Thomas J.; Burns, Stephen A.

2014-01-01

65

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability  

NASA Astrophysics Data System (ADS)

The physical mechanisms of the quasar ultraviolet (UV)-optical variability are not well understood despite the long history of observations. Recently, Dexter & Agol presented a model of quasar UV-optical variability, which assumes large local temperature fluctuations in the quasar accretion discs. This inhomogeneous accretion disc model is claimed to describe not only the single-band variability amplitude, but also microlensing size constraints and the quasar composite spectral shape. In this work, we examine the validity of the inhomogeneous accretion disc model in the light of quasar UV-optical spectral variability by using five-band multi-epoch light curves for nearly 9 000 quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 region. By comparing the values of the intrinsic scatter ?int of the two-band magnitude-magnitude plots for the SDSS quasar light curves and for the simulated light curves, we show that Dexter & Agol's inhomogeneous accretion disc model cannot explain the tight inter-band correlation often observed in the SDSS quasar light curves. This result leads us to conclude that the local temperature fluctuations in the accretion discs are not the main driver of the several years' UV-optical variability of quasars, and consequently, that the assumption that the quasar accretion discs have large localized temperature fluctuations is not preferred from the viewpoint of the UV-optical spectral variability.

Kokubo, Mitsuru

2015-05-01

66

Genotoxic stress accelerates age-associated degenerative changes in intervertebral discs  

PubMed Central

Intervertebral disc degeneration (IDD) is the leading cause of debilitating spinal disorders such as chronic lower back pain. Aging is the greatest risk factor for IDD. Previously, we demonstrated IDD in a murine model of a progeroid syndrome caused by reduced expression of a key DNA repair enzyme. This led us to hypothesize that DNA damage promotes IDD. To test our hypothesis, we chronically exposed adult wild-type (Wt) and DNA repair-deficient Ercc1?/? mice to the cancer therapeutic agent mechlorethamine (MEC) or ionization radiation (IR) to induce DNA damage and measured the impact on disc structure. Proteoglycan, a major structural matrix constituent of the disc, was reduced 3-5x in the discs of MEC- and IR-exposed animals compared to untreated controls. Expression of the protease ADAMTS4 and aggrecan proteolytic fragments were significantly increased. Additionally, new PG synthesis was reduced 2-3x in MEC- and IR-treated discs compared to untreated controls. Both cellular senescence and apoptosis were increased in discs of treated animals. The effects were more severe in the DNA repair-deficient Ercc1?/? mice than in Wt littermates. Local irradiation of the vertebra in Wt mice elicited a similar reduction in PG. These data demonstrate that genotoxic stress drives degenerative changes associated with IDD. PMID:23262094

Nasto, Luigi A.; Wang, Dong; Robinson, Andria R.; Clauson, Cheryl L.; Ngo, Kevin; Dong, Qing; Roughley, Peter; Epperly, Michael; Huq, Saiful M.; Pola, Enrico; Sowa, Gwendolyn; Robbins, Paul D.; Kang, James; Niedernhofer, Laura J.; Vo, Nam V.

2013-01-01

67

Morphological Features and Important Parameters of Large Optic Discs for Diagnosing Glaucoma  

PubMed Central

Purpose To compare the optic disc parameters of glaucomatous eyes to those of non-glaucomatous eyes with large discs. Methods We studied 225 consecutive eyes with large optic discs (>2.82 mm2): 91 eyes with glaucoma and 134 eyes without glaucoma. An eye was diagnosed with glaucoma when visual field defects were detected by the Humphrey Field Analyzer. All of the Heidelberg Retina Tomograph II (HRT II) parameters were compared between the non-glaucomatous and glaucomatous eyes. A logistic regression analysis of the HRT II parameters was used to establish a new formula for diagnosing glaucoma, and the sensitivity and specificity of the Moorfields Regression Analysis (MRA) was compared to the findings made by our analyses. Results The mean disc area was 3.44±0.50 mm2 in the non-glaucomatous group and 3.40±0.52 mm2 in the glaucoma group. The cup area, cup volume, cup-to-disc area ratio, linear cup/disc ratio, mean cup depth, and the maximum cup depth were significantly larger in glaucomatous eyes than in the non-glaucomatous eyes. The rim area, rim volume, cup shape measurement, mean retinal nerve fiber layer (RNFL) thickness, and RFNL cross-sectional area were significantly smaller in glaucomatous eyes than in non-glaucomatous eyes. The cup-to-disc area ratio, the height variation contour (HVC), and the RNFL cross-sectional area were important parameters for diagnosing the early stage glaucoma, and the cup-to-disc area ratio and cup volume were useful for diagnosing advanced stage glaucoma in eyes with a large optic disc. The new formula had higher sensitivity and specificity for diagnosing glaucoma than MRA. Conclusions The cup-to-disc area ratio, HVC, RNFL cross-sectional area, and cup volume were important parameters for diagnosing glaucoma in eyes with a large optic disc. The important disc parameters to diagnose glaucoma depend on the stage of glaucoma in patients with large discs. PMID:25798580

Okimoto, Satoshi; Yamashita, Keiko; Shibata, Tetsuo; Kiuchi, Yoshiaki

2015-01-01

68

The inner diameter of the optic disc pit decreases with pars plana vitrectomy.  

PubMed

To report a patient with optic disc pit who showed decreased inner diameter of the optic disc pit along with resolution of recurrent macular detachment after pars plana vitrectomy. Pneumatic retinopexy and peripapillary laser photocoagulation was performed in a 28-year-old female with optic disc pit and serous macular detachment. Two months after the initial therapy, serous macular detachment recurred. Then, pars plana vitrectomy with removal of the posterior hyaloid was performed, and intraocular perfluoro-octane (C3F8) tamponade was used. Fundus photography and ocular coherence tomography were obtained at each visit. The patient was followed up for 1 year. Visual acuity was 20/400 (Snellen) at first presentation, improved to 20/40 at 2 weeks after pneumatic retinopexy and peripapillary laser treatment. Then, 2 months later visual acuity decreased to 20/200, improved to 20/40 at 2 weeks after the vitreoretinal surgery, and stayed stable during the 1-year follow-up. It was also noticed on clinical examinations as well as fundus photographs that the inner diameter of the optic disc pit had decreased significantly. Vitreous traction plays an important role in the formation of serous macular detachments with optic disc pits. In these patients, pars plana vitrectomy and posterior hyaloid removal may be an effective treatment for reduction of the inner diameter of the optic pit and resolution of the serous macular detachments. PMID:23111570

Pinarci, Eylem Yaman; Karacal, Humeyra; Oncel, Banu; Bayar, Sezin Akca; Karakaya, Muharrem

2013-04-01

69

Playback Signal Processing System Using Improved Waveform Correction for High Density Optical Disc  

NASA Astrophysics Data System (ADS)

A new playback signal processing system capable of large-capacity optical disc playback of over 25GB in the same optical format as the Blu-ray Disc has been developed. Generally, as optical disc capacity increases, the read-out signal of minimum pits is markedly degraded due to inter-symbol interference (ISI) from adjacent pits, asymmetries caused by pit-form distortion, and the frequency characteristics of optical transfer function (OTF). Partial Response Maximum Likelihood (PRML) is known to effectively improve ISI and asymmetries by compensating for these factors electrically. However, in high-density optical discs greater than 25GB, bit errors frequently occur even when PRML is applied. This proposed system consists of a PRML circuit and Improved Waveform Correction circuit that control only read-out signals of minimum pits more surely. Bit error rate (BER) measurements of the playback of a 30GB optical disc showed better BER performance. The system can be realized without major changes to the current PRML system.

Sugiyama, Kazuhiro; Michihata, Satoshi; Fujiyama, Naoyuki; Yoshida, Hideo

70

Familial cavitary optic disc anomalies: Identification of a novel genetic locus  

PubMed Central

PURPOSE To identify the chromosomal location of the gene involved in the pathogenesis of cavitary optic disc anomalies in a large pedigree with autosomal dominant inheritance of disease. DESIGN Linkage analysis of a pedigree affected with cavitary optic disc anomalies. METHODS Optic disc photographs were examined for the presence of cavitary optic disc anomalies. Sixteen affected family members and one obligate carrier were identified and studied with linkage analysis using both microarrays of single nucleotide polymorphisms (SNPs) and short tandem repeat polymorphism (STRP) markers. RESULTS Multipoint linkage analysis of SNP genotypes yielded a maximum nonparametric LOD score of 21.7 with markers located on chromosome 12q. Linkage was confirmed with 16 STRP markers in the 12q region. A maximum two point LOD score of 4.06 (?=0) was obtained with marker D12S1700. The disease interval defined by observed recombinants is 9.1 cM, which corresponds to 13.5 Mbp. Three candidate genes (GDF-11, NEUROD4, and WIF1) in the chromosome 12q locus were evaluated as possible disease-causing genes. No mutations were detected in the coding sequence of these genes. DISCUSSION The discovery of the chromosomal location of a gene responsible for cavitary optic disc anomalies is a key step in identifying the genetic basis of this condition and may ultimately provide important insight into the pathogenesis of more common optic nerve diseases such as normal tension glaucoma and primary open angle glaucoma. PMID:17368552

Fingert, John H.; Honkanen, Robert A.; Shankar, Suma P.; Affatigato, Louisa M.; Ehlinger, Mary A.; Moore, Michael D.; Jampol, Lee M.; Sheffield, Val C.; Stone, Edwin M.; Alward, Wallace L.M.

2007-01-01

71

Optic Disc and Cup Segmentation from Color Fundus Photograph Using Graph Cut with Priors  

PubMed Central

For automatic segmentation of optic disc and cup from color fundus photograph, we describe a fairly general energy function that can naturally fit into a global optimization framework with graph cut. Distinguished from most previous work, our energy function includes priors on the shape & location of disc & cup, the rim thickness and the geometric interaction of “disc contains cup”. These priors together with the effective optimization of graph cut enable our algorithm to generate reliable and robust solutions. Our approach is able to outperform several state-of-the-art segmentation methods, as shown by a set of experimental comparisons with manual delineations and a series of results of correlations with the assessments of a merchant-provided software from Optical Coherence Tomography (OCT) regarding several cup and disc parameters. PMID:24579126

Zheng, Yuanjie; Stambolian, Dwight; O’Brien, Joan; Gee, James C.

2014-01-01

72

Snapshot of degenerative aging of porcine intervertebral disc: a model to unravel the molecular mechanisms  

PubMed Central

Larger animal models, such as porcine, have been validated as appropriate models of the human disc with respect to biomechanics and biochemistry. They are advantageous for research as the models are relatively straightforward to prepare and easily obtainable for research to perform surgical techniques. The intention of this study was to quantitatively analyze gene expression for collagen and proteoglycan components of the extracellular matrix and for collagenase (MMP-1) in porcine discs of varying ages (Newborn; 2-3weeks, Mature; 6-9 month, Older; 2-3 years). In this study, we observed that the cell number and GAG (glycosaminoglycan) formation dramatically decreased with aging. Also, gene expression in the annulus fibrosus (AF) and nucleus pulposus (NP) cells changed with aging. The level of MMP-1 mRNA increased with age and both type I, II collagens decreased with age. The level of aggrecan mRNA was highest in the mature group and decreased significantly with aging. In the mature group, MMP-1 expression was minimal compared to the newborn group. In AF cells, type II collagen was expressed at a high level in the mature group with a higher level of aggrecan, when aged NP showed a decrease in type II collagen. The model of IVD degeneration in the porcine disc shows many changes in gene expression with age that have been previously documented for human and may serve as a model for studying changes in IVD metabolism with age. We concluded that the porcine model is excellent to test hypotheses related to disc degeneration while permitting time-course study in biologically active systems. PMID:21499012

Cho, Hongsik; Park, Sang-Hyug; Lee, Sangmin; Kang, Miji

2011-01-01

73

Agreement of glaucoma specialists and experienced optometrists in gonioscopy and optic disc evaluation  

PubMed Central

Purpose To compare the diagnostic performance of glaucoma specialists and experienced optometrists in gonioscopy and optic disc assessment. Methods This study was done to validate the diagnostic performance of two experienced optometrists for using their skills of detecting glaucoma using gonioscopy and optic disc assessment in a major epidemiological study, the L V Prasad Eye Institute Glaucoma Epidemiology and Molecular Genetics Study (LVPEI-GLEAMS). Gonioscopic findings for 150 eyes were categorized as 0, 1 and 2 for open angle, primary angle closure suspect (PACS) and primary angle closure (PAC) respectively. Optic disc findings for 200 eyes were categorized as 0, 1 and 2 for normal, suspects and glaucomatous respectively. Weighted kappa (?) and diagnostic accuracy parameters were calculated. Two optometrists (#1 and #2) participated in the study. Results Agreement between glaucoma specialists and optometrist for interpretation of gonioscopy to discriminate PACS and PAC from open angles and for interpretation of optic disc to discriminate glaucomatous and suspicious discs from normal, the kappa (?) was 0.92 and 0.84 and 0.90 and 0.89 for optometrists #1 and #2 respectively. Sensitivities and specificities were above 90% for gonioscopy. Optic disc evaluation had specificities greater than 95% to discriminate normal from glaucomatous discs while the sensitivities were 83% and 93% for optometrists #1 and #2 respectively. Conclusion Agreement between optometrists and glaucoma specialists, in diagnostic performance of gonioscopy and optic assessment was excellent with high sensitivity and specificity. Hence, we conclude that the experienced optometrists can detect glaucoma accurately in the LVPEI-GLEAMS.

Kumar, Addepalli U.; Jonnadula, Ganesh B.; Garudadri, Chandrasekhar; Rao, Harsha L.; Senthil, Sirisha; Papas, Eric B.; Sankaridurg, Padmaja; Khanna, Rohit C.

2013-01-01

74

Advanced optimization method for spherical aberration and focus offset for optical disc drive  

NASA Astrophysics Data System (ADS)

We developed an optimization method for spherical aberration and focus offset for an optical disc drive using an elliptical approximation. This method measures the small number of points that are located at specific positions. Furthermore, it approximates a characteristic distribution to an ellipse and calculates the center of the ellipse as the optimal point. The effectiveness of this method is experimentally confirmed using Blu-ray discs with three types of protective layer of various thicknesses.

Kishigami, Tomo; Kanatake, Yusuke; Takeshita, Nobuo

2014-09-01

75

Development of Integrated Small-Form-Factor Optical Pickup with Blu-ray Disc Specification  

Microsoft Academic Search

In this study, a small-form-factor optical pickup (SFFOP), corresponding to the Blu-ray disc (BD) specifications has been developed. The developed SFFOP is composed of an integrated optical pickup and a swing-arm-type actuator. The integrated optical pickup has been developed in the form of an array using wafer-level fabrication technology. The developed SFFOP is composed of the fundamental optics which yields

Sung-Mook Kang; Jin-Eui Lee; Wan-Chin Kim; No-Cheol Park; Young-Pil Park; Eun-Hyoung Cho; Jin-Seung Sohn; Sung-Dong Suh

2006-01-01

76

The Spectrum of Optic Disc Ischemia in Patients Younger than 50 Years (An Amercian Ophthalmological Society Thesis)  

PubMed Central

Purpose: To identify the spectrum of clinical and fluorescein angiographic features of optic disc ischemia in patients younger than 50 years. Methods: This retrospective comparative case series from a university consultative neuro-ophthalmology practice consisted of two phases. The first compared 108 cases of nonarteritic anterior ischemic optic neuropathy in patients younger than 50 years (NAIONy) to a cohort of 108 cases in patients 50 years or older (NAIONo). Predisposing risk factors, fluorescein angiographic features, and clinical course were compared. In the second phase, 12 cases of diabetic papillopathy under age 50 were assessed by fluorescein angiographic criteria for evidence of optic disc ischemia and compared to patients with NAIONy. Results: NAIONy comprised 108 (12.7%) of 848 NAION cases reviewed. Chronic renal failure with dialysis and migraine were more common in NAIONy. Fellow eye involvement rate was significantly higher for NAIONy patients (46/108, 42.6%) than for NAIONo patients (32/108, 29.6%). Fluorescein angiographic features of ischemia were documented in 44 (81.5%) of 54 eyes studied. In one case, these features were documented in pre-NAION edema. Diabetic papillopathy demonstrated delayed filling consistent with ischemia in 7 of 10 (70.0%), without significant visual field loss. Conclusions: Ischemic optic neuropathy in patients younger than 50 years is not rare. Fellow eye involvement is more frequent in younger patients. Fluorescein angiography confirmation of impaired perfusion in multiple syndromes of optic neuropathy corroborates a spectrum of optic disc ischemia ranging from perfusion delay without visual loss to severely impaired perfusion and visual loss and incorporates optic neuropathies previously considered nonischemic. PMID:24167327

Arnold, Anthony C.; Costa, Roberta M. S.; Dumitrascu, Oana M.

2013-01-01

77

Aging changes of the optic nerve head in relation to open angle glaucoma  

PubMed Central

AIMS—To determine the age related changes in optic nerve head structure in a group of normal subjects and assess the significance of any changes in relation to those found in open angle glaucoma.?METHODS—A group of 88 white volunteers and friends and spouses of patients with a normal visual field and normal intraocular pressure was studied. Two different imaging and measurement devices were used (computer assisted planimetry and scanning laser ophthalmoscopy), and the results from each were compared. Measurements were made of the optic disc, optic cup, and neuroretinal rim areas, and the vertical optic disc diameter and cup/disc diameter ratio.?RESULTS—Neuroretinal rim area declined at the rate of between 0.28% and 0.39% per year. Vertical optic cup diameter and optic cup area increased with age. The mean cup/disc diameter ratio increased by about 0.1 between the ages of 30 and 70 years.?CONCLUSIONS—Age related changes are significant and measurable, and should be taken into account when assessing the glaucoma suspect, and when estimating the rate of progression of glaucomatous optic neuropathy in patients with established disease.?? PMID:9486023

Garway-Heath, D; Wollstein, G; Hitchings, R

1997-01-01

78

Teaching of optics in the optics age  

NASA Astrophysics Data System (ADS)

The present Optics Age of science had not been foreseen by curriculum- makers in many countries. The result is that during the last 25 years when activity in science, engineering, technology and industry related to optics and lasers was exploding in the advanced countries optics was being de-emphasized in curricula in these countries. The consequence is that these countries including India have not played good enough a role. It is shown that the changes needed are more in attitude, pedagogic tools, terminology, and teaching methodology than in curricular contents. Examples: (1) The sequence of topics be changed, (2) The concept of coherence be introduced by considering thought experiments with different light sources; it is shown that the Michelson interferometer along with an HeNe laser can be used to introduce spatial as well as temporal coherence, (3) Modern terminology be used, (4) Crystal optics which is difficult be divorced from the concept of polarization which is simple; greater attention be paid to polarization helix than to polarization ellipse so that the confusion in 'handedness' is eliminated, (5) Group velocity be introduced as related to stationary phase approximation, (6) Modern terms like irradiance, temporal, spatial, frequency spectrum, spatial frequency, etc be used extensively, and so on.

Parasnis, A. S.

1995-10-01

79

Exhaustion of nucleus pulposus progenitor cells with ageing and degeneration of the intervertebral disc  

PubMed Central

Despite the high prevalence of intervertebral disc disease, little is known about changes in intervertebral disc cells and their regenerative potential with ageing and intervertebral disc degeneration. Here we identify populations of progenitor cells that are Tie2 positive (Tie2+) and disialoganglioside 2 positive (GD2+), in the nucleus pulposus from mice and humans. These cells form spheroid colonies that express type II collagen and aggrecan. They are clonally multipotent and differentiated into mesenchymal lineages and induced reorganization of nucleus pulposus tissue when transplanted into non-obese diabetic/severe combined immunodeficient mice. The frequency of Tie2+ cells in tissues from patients decreases markedly with age and degeneration of the intervertebral disc, suggesting exhaustion of their capacity for regeneration. However, progenitor cells (Tie2+GD2+) can be induced from their precursor cells (Tie2+GD2?) under simple culture conditions. Moreover, angiopoietin-1, a ligand of Tie2, is crucial for the survival of nucleus pulposus cells. Our results offer insights for regenerative therapy and a new diagnostic standard. PMID:23232394

Sakai, Daisuke; Nakamura, Yoshihiko; Nakai, Tomoko; Mishima, Taishi; Kato, Shunichi; Grad, Sibylle; Alini, Mauro; Risbud, Makarand V.; Chan, Danny; Cheah, Kathryn S.E.; Yamamura, Ken-ichi; Masuda, Koichi; Okano, Hideyuki; Ando, Kiyoshi; Mochida, Joji

2012-01-01

80

Optic Disc Segmentation by Balloon Snake with Texture from Color Fundus Image  

PubMed Central

A well-established method for diagnosis of glaucoma is the examination of the optic nerve head based on fundus image as glaucomatous patients tend to have larger cup-to-disc ratios. The difficulty of optic segmentation is due to the fuzzy boundaries and peripapillary atrophy (PPA). In this paper a novel method for optic nerve head segmentation is proposed. It uses template matching to find the region of interest (ROI). The method of vessel erasing in the ROI is based on PDE inpainting which will make the boundary smoother. A novel optic disc segmentation approach using image texture is explored in this paper. A cluster method based on image texture is employed before the optic disc segmentation step to remove the edge noise such as cup boundary and vessels. We replace image force in the snake with image texture and the initial contour of the balloon snake is inside the optic disc to avoid the PPA. The experimental results show the superior performance of the proposed method when compared to some traditional segmentation approaches. An average segmentation dice coefficient of 94% has been obtained.

Sun, Jinyang; Luan, Fangjun; Wu, Hanhui

2015-01-01

81

Liquid Immersion Deep-UV Optical Disc Mastering for Blu-ray Disc Read-Only Memory  

Microsoft Academic Search

The liquid immersion mastering technique has been successfully applied to the mastering of read-only memory (ROM) discs for the Blu-ray disc (BD) system. Replicated discs with a density corresponding to 25 GB in a single layer on a 12 cm disc showed a bottom jitter of less than 5%. Results concerning process latitude and disc uniformity are presented. A full-format

Jaap H. M. Neijzen; Erwin R. Meinders; Helmar van Santen

2004-01-01

82

Evaluation of subjects with a moderate cup to disc ratio using optical coherence tomography and Heidelberg retina tomograph 3: Impact of the disc area  

PubMed Central

Aim: The aim was to evaluate subjects with a moderate cup to disc ratio using optical coherence tomograph (OCT) and Heidelberg retina tomograph (HRT) 3. Settings and Design: We included 80 patients with early glaucoma and 80 nonglaucomatous subjects with moderate cup/disc ratio (range of 0.5–0.8) to this cross-sectional study. Subjects and Methods: We compared results of color-coded algorithms of HRT 3 (Moorfields regression analysis [MRA] and Glaucoma probability score [GPS]) and OCT. All outputs are classified into three categories: Within normal limits (WNLs), borderline and outside normal limits (ONLs). Diagnostic accuracies of algorithms were determined using the highest sensitivity criteria. Results: The sensitivities of global MRA, GPS and OCT were 0.75, 0.925 and 0.725, respectively, in average disc area group and 0.85, 1.0 and 0.425, respectively, in large disc area group. The specificities of global MRA, GPS and OCT were 0.55, 0.15 and 0.85, respectively, in average disc area group and 0.425, 0.025 and 0.80, respectively, in large disc area group. Area under receiver operating characteristic curve (AUROC) of global MRA, GPS and OCT were 0.667, 0.617 and 0.792, respectively, in average disc area group and 0.746, 0.576 and 0.627, respectively, in large disc area group. AUROC of global MRA and OCT combination in the average and large disc area groups were 0.828 and 0.825, respectively. Conclusions: In contrast to GPS and OCT algorithms, diagnostic performance of MRA algorithm increased in large disc area group. Combining MRA and OCT algorithms produced satisfactory diagnostic performance in subjects with an average and large disc area. PMID:25686054

Ula?, Fatih; Do?an, Ümit; Kaymaz, Abdulgani; Çelik, Fatih; Çelebi, Serdal

2015-01-01

83

Optical effects related to Keplerian discs orbiting Kehagias-Sfetsos naked singularities  

NASA Astrophysics Data System (ADS)

We demonstrate possible optical signatures of the Kehagias-Sfetsos (KS) naked singularity spacetimes representing a spherically symmetric vacuum solution of the modified Ho?ava gravity. In such spacetimes, accretion structures significantly different from those present in standard black hole spacetimes occur due to the ‘antigravity’ effect, which causes an internal static sphere surrounded by Keplerian discs. We focus our attention on the optical effects related to the Keplerian accretion discs, constructing the optical appearance of the Keplerian discs, the spectral continuum due to their thermal radiation, and the spectral profiled lines generated in the innermost parts of such discs. The KS naked singularity signature is strongly encoded in the characteristics of predicted optical effects, especially in cases where the spectral continuum and spectral lines are profiled by the strong gravity of the spacetimes due to the vanishing region of the angular velocity gradient influencing the effectiveness of the viscosity mechanism. We can conclude that optical signatures of KS naked singularities can be well distinguished from the signatures of standard black holes.

Stuchlík, Zden?k; Schee, Jan

2014-10-01

84

Promising Rapid Access High-Capacity Mass Storage Technique For Diagnostic Information Utilizing Optical Disc  

NASA Astrophysics Data System (ADS)

The optical disc has become a new technique for mass digital data storage of X-ray images from examinations and films in todays hospitals. Up to 36,000 X-ray images can be stored on one side of a 12-inch disc by melting holes 0.015 mils in size in an ablative material such as tellerium with a laser beam. This unique characteristic makes the disc suitable for storage and retrieval of X-rays in a record and playback system in either a single disc or multiple disc "jukebox" configuration. Doctors, nurses, technicians and other hospital personnel can call up a particular X-ray in less than 0.6 of a second in an on-line single disc system and up to less than 6 seconds in an on-line "jukebox" system. The jukebox is configured to hold up to 100 discs, thus storing 3,600,000 X-rays in hospitals with a bed size of greater than 500. The estimated exposed films on file in those hospitals is 327,400,000 and the estimated annual X-ray exams are 44,300. Thus, a single disc system could be used for an all electronic X-ray scanning system for annual X-ray exams. The jukebox configuration, which has expansion capability for servicing multiple simultaneous user request, can be applied to large archival mass storage. These systems could store the existing exposed films in hospitals with bed size greater than 500 at record and playback data rates of 50 Mb/s with access times of less than 15 seconds.

Colby, R. L.; Bartuska, A. J.; Herzog, D. G.

1982-01-01

85

Choosing an Optical Disc System: A Guide for Users and Resellers.  

ERIC Educational Resources Information Center

Presents a guide for selecting an optional disc system. Highlights include storage hierarchy; standards; data life cycles; security; implementing an optical jukebox system; optimizing the system; performance; quality and reliability; software; cost of online versus near-line; and growing opportunities. Sidebars provide additional information on…

Vane-Tempest, Stewart

1995-01-01

86

Blu-ray Disc\\/DVD Compa tible Optical Slim Pickup for Video Camera Drives  

Microsoft Academic Search

A blu-ray disc (BD) \\/ DVD compatible optical slim pickup for video camera drives has been developed. In order to achieve both BD \\/ DVD compatibility and the compact size, a dual objective lens method, collimator lens actuation for spherical aberration compensation, and shared front monitor (FM) were newly developed.

K. Yamazaki; H. Mori; T. Kawamura; Y. Kitada; T. Kamisada

2008-01-01

87

Surgical treatment of macular detachment secondary to congenital pit of the optic disc: case report.  

PubMed

The authors describe a patient with macular detachment in the right eye, secondary to congenital pit of the optic disc, submitted to vitrectomy, drainage of the subretinal fluid, perfluorocarbon, endolaser and perfluoropropane gas (C3F8). A sample of the vitreous humor was taken for comparative analysis with the subretinal fluid. Results of retinography, optical coherence tomography, and illustrations of the surgical procedure are presented. Optical coherence tomography revealed the detachment resolved 6 months after surgery. Visual acuity improved from 20/400 to 20/30. This surgical technique can lead to successful reattachment of the macula and improvement of central vision. Additionally, a qualitative and comparative analysis showed a similar biochemical composition of the subretinal fluid and the vitreous. Despite technical limitations, this analysis can confirm the pathophysiology of the disease, suggesting that the subretinal fluid may originate from the vitreous cavity in macular detachment secondary to congenital pit of the optic disc. PMID:19169525

Maia, Otacilio de Oliveira; Soriano, Danilo Sone; Takahashi, Walter Yukihiko; Suzuki, Hisashi

2008-01-01

88

MEMS focus control and spherical aberration correction for multilayer optical discs  

NASA Astrophysics Data System (ADS)

We present the use of a large-stroke deformable membrane mirror at 45° incidence to achieve a very compact optical system capable of fast multi-layer focusing in an optical disc unit. The MEMS mirror replaces a lens translation mechanism and liquid crystal compensator, resulting in a single optical element to control both focus depth and compensation of attendant focus-dependent spherical aberration. We outline the membrane optical requirements in terms of stroke and aberration compensation required for multi-layer focusing for current DVD and BD standards. We demonstrate an adjustable range of at least 1.6 ?m peak wavefront spherical aberration correction at a membrane displacement of 7 ?m, which should be sufficient capability for quadruple layer BDXL™ discs.

Lukes, Sarah J.; Dickensheets, David L.

2012-03-01

89

Unifying disc-jet behaviour in X-ray binaries: an optical/IR approach  

E-print Network

Synchrotron emission from jets produced by X-ray binaries can be detected at optical and infrared (IR) frequencies. I show that optical/IR colour-magnitude diagrams of the outbursts of nine X-ray binaries successfully separate thermal disc emission from non-thermal jet emission, in both black hole and neutron star sources. A heated single-temperature blackbody is able to reproduce the observed relations between colour and magnitude, except when excursions are made to a redder colour than expected, which is due to jet emission. The general picture that is developed is then incorporated into the unified picture of disc-jet behaviour in black hole X-ray binaries. At a given position of a source in the X-ray hardness-intensity diagram, the radio, IR and optical properties can be inferred. Similarly, it is possible to predict the X-ray and radio luminosities and spectral states from optical/IR monitoring.

David M. Russell; Dipankar Maitra; Rob P. Fender; Fraser Lewis

2008-11-18

90

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability  

E-print Network

The physical mechanisms of the quasar ultraviolet (UV)-optical variability are not well understood despite the long history of observations. Recently, Dexter & Agol presented a model of quasar UV-optical variability, which assumes large local temperature fluctuations in the quasar accretion discs. This inhomogeneous accretion disc model is claimed to describe not only the single-band variability amplitude, but also microlensing size constraints and the quasar composite spectral shape. In this work, we examine the validity of the inhomogeneous accretion disc model in the light of quasar UV-optical spectral variability by using five-band multi-epoch light curves for nearly 9 000 quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 region. By comparing the values of the intrinsic scatter $\\sigma_{\\text{int}}$ of the two-band magnitude-magnitude plots for the SDSS quasar light curves and for the simulated light curves, we show that Dexter & Agol's inhomogeneous accretion disc model cannot explain the ...

Kokubo, Mitsuru

2015-01-01

91

Glaucoma-Induced Optic Disc Morphometric Changes and Glaucoma Diagnostic Ability of Heidelberg Retina Tomograph II in Highly Myopic Eyes  

PubMed Central

Purpose This study was performed to first investigate the morphological differences in the optic nerve head between highly myopic non-glaucomatous controls and highly myopic glaucomatous eyes in comparison with the differences between emmetropic non-glaucomatous controls and emmetropic glaucomatous eyes using confocal scanning laser ophthalmoscopy. Further, the ability of the apparatus in glaucoma diagnosis in highly myopic eyes was compared with that in emmetropic eyes. Methods Healthy subjects and age-matched patients with early-stage open-angle glaucoma were divided into two groups: emmetropic eyes (?1.0 to +1.0 diopters) and highly myopic eyes (?12.0 to ?5.0 diopters).The participants were comprised of 65 emmetropic normal eyes, 59 emmetropic glaucomatous eyes, 62 highly myopic normal eyes, and 68 highly myopic glaucomatous eyes and eyes with pathologic myopia were carefully excluded. Confocal scanning laser tomographic parameters were compared among all subjects after adjustment for age and disc area. The ROC curves and sensitivity and specificity for glaucoma detection using several clinical methods were then compared between the emmetropic and highly myopic eyes. Results Rim area, cup/disc area ratio, mean cup depth, and cup shape measure of glaucoma eyes are significantly different from those of normal eyes in both highly myopic eyes and emmetropic eyes. Methodological overestimation of retinal nerve fiber layer cross sectional area due to optic disc tilting was suggested in the highly myopic eyes. The diagnostic performance of glaucoma using several discriminant methods significantly deteriorated in the highly myopic eyes. Conclusions In the highly myopic glaucomatous eyes, confocal scanning laser tomographic parameters were significantly different from that of non-glaucomatous highly myopic eyes but diagnostic performance of glaucoma was deteriorated than that in emmetropic eyes. These findings demonstrate the utility and limitations of the apparatus in diagnosing glaucoma in highly myopic patients. PMID:24475117

Mayama, Chihiro; Tsutsumi, Tae; Saito, Hitomi; Asaoka, Ryo; Tomidokoro, Atsuo; Iwase, Aiko; Otani, Shinichiro; Miyata, Kazunori; Araie, Makoto

2014-01-01

92

Point-of-care ultrasonography for the identification of 2 children with optic disc drusen mimicking papilledema.  

PubMed

We present 2 cases of asymptomatic patients who were found to have raised and blurred optic discs on physical examination, suggestive of papilledema. Evaluation in the emergency department revealed 2 well-appearing children with normal vital signs and neurologic evaluation results, without symptoms of increased intracranial pressure. Point-of-care ocular ultrasonography was performed on both children, demonstrating calcification at the optic nerve, which is diagnostic of optic disc drusen. Optic disc drusen is caused by the deposition of calcified axonal debris and is often buried within the optic disc in pediatric patients. It can cause some changes in visual acuity and visual fields, but patients who are otherwise asymptomatic can be easily diagnosed through point-of-care ultrasound, thereby sparing patients an aggressive workup if their clinical picture is otherwise reassuring. PMID:24987997

Braun, Alanna; Doniger, Stephanie J

2014-07-01

93

Single intravitreal ranibizumab injection for optic disc neovascularisation due to possibly traumatic, direct carotid cavernous fistula.  

PubMed

We report a patient with optic disc neovasculariation due to possibly traumatic direct carotid cavernous fistula treated by a single dose of intravitreal ranibizumab prior to neurointervention. A 25-year-old man had a 10-month history of bilateral proptosis and left sixth nerve paralysis was evaluated. Conjunctival vessels were markedly dilated, especially in the left eye. Clinical examination and fundus fluorescein angiography revealed disc neovascularisation in the left eye with subtle peripheral retinal ischaemia. Magnetic resonance imaging suggested a high-flow carotid cavernous fistula on the left side and this was confirmed by catheter angiography. A single dose of intravitreal ranibizumab was injected prior to neuro-intervention. The disc neovascularisation regressed completely three days later. The left direct carotid cavernous fistula was later treated successfully with coil embolisation. Optic disc neovascularisation is a very rare feature of carotid cavernous fistula and intravitreal ranibizumab may be a useful therapeutic adjunct prior to neuro-interventional techniques to reduce neovascularisation-induced haemorrhage following the intervention. PMID:23560946

Saatci, Ali Osman; Selver, Ozlem Barut; Men, Suleyman; Bajin, Meltem Soylev

2014-01-01

94

Expression and regulation of metalloproteinases and their inhibitors in intervertebral disc aging and degeneration  

PubMed Central

BACKGROUND CONTEXT Destruction of extracellular matrix (ECM) leads to intervertebral disc degeneration (IDD), which underlies many spine-related disorders. Matrix metalloproteinases (MMPs), and disintegrins and metalloproteinases with thrombospondin motifs (ADAMTSs) are believed to be the major proteolytic enzymes responsible for ECM degradation in the intervertebral disc (IVD). PURPOSE To summarize the current literature on gene expression and regulation of MMPs, ADAMTSs, and tissue inhibitors of metalloproteinases (TIMPs) in IVD aging and IDD. METHODS A comprehensive literature review of gene expression of MMP, ADAMTS, and TIMP in human IDD and reported studies on regulatory factors controlling their expressions and activities in both human and animal model systems. RESULTS Upregulation of specific MMPs (MMP-1, -2, -3, -7, -8, -10, and -13) and ADAMTS (ADAMTS-1, -4, and -15) were reported in human degenerated IVDs. However, it is still unclear from conflicting published studies whether the expression of ADAMTS-5, the predominant aggrecanase, is increased with IDD. Tissue inhibitors of metalloproteinase-3 is downregulated, whereas TIMP-1 is upregulated in human degenerated IVDs relative to nondegenerated IVDs. Numerous studies indicate that the expression levels of MMP and ADAMTS are modulated by a combination of many factors, including mechanical, inflammatory, and oxidative stress, some of which are mediated in part through the p38 mitogen-activated protein kinase pathway. Genetic predisposition also plays an important role in determining gene expression of MMP-1, -2, -3, and -9. CONCLUSIONS Upregulation of MMP and ADAMTS expression and enzymatic activity is implicated in disc ECM destruction, leading to the development of IDD. Future IDD therapeutics depends on identifying specific MMPs and ADAMTSs whose dysregulation result in pathological proteolysis of disc ECM. PMID:23369495

Vo, Nam V.; Hartman, Robert A.; Yurube, Takashi; Jacobs, Lloydine J.; Sowa, Gwendolyn A.; Kang, James D.

2013-01-01

95

ISSLS PRIZE WINNER: INHIBITION OF NF-?B ACTIVITY AMELIORATES AGE-ASSOCIATED DISC DEGENERATION IN A MOUSE MODEL OF ACCELERATED AGING  

PubMed Central

Study Design NF-?B activity was pharmacologically and genetically blocked in an accelerated aging mouse model to mitigate age-related disc degenerative changes. Objective To study the mediatory role of NF-?B signaling pathway in age-dependent intervertebral disc degeneration. Summary of Background Data Aging is a major contributor to intervertebral disc degeneration (IDD), but the molecular mechanism behind this process is poorly understood. NF-?B is a family of transcription factors which play a central role in mediating cellular response to damage, stress, and inflammation. Growing evidence implicates chronic NF-?B activation as a culprit in many aging-related diseases, but its role in aging-related IDD has not been adequately explored. We studied the effects of NF-?B inhibition on IDD using a DNA repair-deficient mouse model of accelerated aging (Ercc1-/? mice) previously been reported to exhibit age-related IDD. Methods Systemic inhibition of NF-?B activation was achieved either genetically by deletion of one allele of the NF-?B subunit p65 (Ercc1-/?p65+/- mice) or pharmacologically by chronic intra-peritoneal administration of the Nemo Binding Domain (8K-NBD) peptide to block the formation of the upstream activator of NF-?B, I?B Inducible Kinase (IKK), in Ercc1-/? mice. Disc cellularity, total proteoglycan content and proteoglycan synthesis of treated mice and untreated controls were assessed. Results Decreased disc matrix proteoglycan content, a hallmark feature of IDD, and elevated disc NF-?B activity were observed in discs of progeroid Ercc1-/? mice and naturally aged wild-type compared to young WT mice. Systemic inhibition of NF-?B by the 8K-NBD peptide in Ercc1-/? mice increased disc proteoglycan synthesis and ameriolated loss disc cellularity and matrix proteoglycan. These results were confirmed genetically by using the p65 haploinsufficient Ercc1-/?p65+/- mice. Conclusion These findings demonstrate that the IKK/NF-?B signaling pathway is a key mediator of age-dependent IDD and represents a therapeutic target for mitigating disc degenerative diseases associated with aging. PMID:22343279

Nasto, Luigi A.; Seo, Hyoung-Yeon; Robinson, Andria R.; Tilstra, Jeremy S.; Clauson, Cheryl L.; Sowa, Gwendolyn A.; Ngo, Kevin; Dong, Qing; Pola, Enrico; Lee, Joon Y.; Niedernhofer, Laura J.; Kang, James D.; Robbins, Paul D.; Vo, Nam V.

2012-01-01

96

Two-stage feedforward tracking control system with error-based disturbance observer for optical discs  

NASA Astrophysics Data System (ADS)

Recently, the scaling up of the storage capacity and data transfer rate of digital storage media has been required. However, increasing in the storage capacity and transfer rate makes optical head control more difficult. Thus, a tracking control system for optical discs must exhibit a high degree of precision control. Consequently, a new two-stage feedforward control (TSFFC) system for high-precision control is proposed in this paper. The proposed system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and an error-based disturbance observer (EDOB) that uses a notch filter to suppress non periodic disturbances. The proposed control system is designed for DDU-1000 for digital versatile discs (DVDs). The experimental results demonstrate that the proposed system effectively suppresses tracking errors.

Sakimura, Naohide; Ohashi, Takahiro; Ohishi, Kiyoshi; Miyazaki, Toshimasa

2014-09-01

97

Method and system for assigning a confidence metric for automated determination of optic disc location  

DOEpatents

A method for assigning a confidence metric for automated determination of optic disc location that includes analyzing a retinal image and determining at least two sets of coordinates locating an optic disc in the retinal image. The sets of coordinates can be determined using first and second image analysis techniques that are different from one another. An accuracy parameter can be calculated and compared to a primary risk cut-off value. A high confidence level can be assigned to the retinal image if the accuracy parameter is less than the primary risk cut-off value and a low confidence level can be assigned to the retinal image if the accuracy parameter is greater than the primary risk cut-off value. The primary risk cut-off value being selected to represent an acceptable risk of misdiagnosis of a disease having retinal manifestations by the automated technique.

Karnowski, Thomas P. (Knoxville, TN); Tobin, Jr., Kenneth W. (Harriman, TN); Muthusamy Govindasamy, Vijaya Priya (Knoxville, TN); Chaum, Edward (Memphis, TN)

2012-07-10

98

Multimodal segmentation of optic disc and cup from stereo fundus and SD-OCT images  

NASA Astrophysics Data System (ADS)

Glaucoma is one of the major causes of blindness worldwide. One important structural parameter for the diagnosis and management of glaucoma is the cup-to-disc ratio (CDR), which tends to become larger as glaucoma progresses. While approaches exist for segmenting the optic disc and cup within fundus photographs, and more recently, within spectral-domain optical coherence tomography (SD-OCT) volumes, no approaches have been reported for the simultaneous segmentation of these structures within both modalities combined. In this work, a multimodal pixel-classification approach for the segmentation of the optic disc and cup within fundus photographs and SD-OCT volumes is presented. In particular, after segmentation of other important structures (such as the retinal layers and retinal blood vessels) and fundus-to-SD-OCT image registration, features are extracted from both modalities and a k-nearest-neighbor classification approach is used to classify each pixel as cup, rim, or background. The approach is evaluated on 70 multimodal image pairs from 35 subjects in a leave-10%-out fashion (by subject). A significant improvement in classification accuracy is obtained using the multimodal approach over that obtained from the corresponding unimodal approach (97.8% versus 95.2%; p < 0:05; paired t-test).

Miri, Mohammad Saleh; Lee, Kyungmoo; Niemeijer, Meindert; Abràmoff, Michael D.; Kwon, Young H.; Garvin, Mona K.

2013-03-01

99

One-Beam Push-Pull Method with Simple Holographic Optical Element for Multilayer Blu-ray Discs  

NASA Astrophysics Data System (ADS)

The use of a multilayer is efficient for increasing the recording capacity of optical discs, but the unnecessary layer cross talk affected by the stray light is also increased. Layer crosstalk should be suppressed to realize a stable tracking servo system. A one-beam push-pull method with a simple holographic optical element for a multilayer Blu-ray disc is proposed, and its effectiveness in suppressing the layer crosstalk was experimentally confirmed.

Nakahara, Hironori; Ohmaki, Masayuki; Shinoda, Masahisa; Matozaki, Toshiya; Takeshita, Nobuo

2011-09-01

100

Quantitative chemical tagging, stellar ages and the chemo-dynamical evolution of the Galactic disc  

NASA Astrophysics Data System (ADS)

The early science results from the new generation of high-resolution stellar spectroscopic surveys, such as Galactic Archaeology with HERMES (GALAH) and the Gaia European Southern Observatory survey (Gaia-ESO), will represent major milestones in the quest to chemically tag the Galaxy. Yet this technique to reconstruct dispersed coeval stellar groups has remained largely untested until recently. We build on previous work that developed an empirical chemical tagging probability function, which describes the likelihood that two field stars are conatal, that is, they were formed in the same cluster environment. In this work, we perform the first ever blind chemical tagging experiment, i.e. tagging stars with no known or otherwise discernible associations, on a sample of 714 disc field stars with a number of high-quality high-resolution homogeneous metal abundance measurements. We present evidence that chemical tagging of field stars does identify coeval groups of stars, yet these groups may not represent distinct formation sites, e.g. as in dissolved open clusters, as previously thought. Our results point to several important conclusions, among them that group finding will be limited strictly to chemical abundance space, e.g. stellar ages, kinematics, colours, temperature and surface gravity do not enhance the detectability of groups. We also demonstrate that in addition to its role in probing the chemical enrichment and kinematic history of the Galactic disc, chemical tagging represents a powerful new stellar age determination technique.

Mitschang, A. W.; De Silva, G.; Zucker, D. B.; Anguiano, B.; Bensby, T.; Feltzing, S.

2014-03-01

101

Reproducibility of RTVue Retinal Nerve Fiber Layer Thickness and Optic Disc Measurements and Agreement with Stratus Optical Coherence Tomography Measurements  

PubMed Central

PURPOSE To evaluate RTVue spectral-domain optical coherence tomography (OCT) (Optovue Inc, Fremont, California, USA) reproducibility and to assess agreement with Stratus time-domain OCT (Carl Zeiss Meditec, Dublin, California, USA) measurements. DESIGN Observational clinical study. METHODS Scans were obtained from both eyes of all participants 3 times using the RTVue nerve head map 4-mm diameter protocol and once using Stratus OCT within the same session. RTVue reproducibility and agreement with Stratus OCT were evaluated for retinal nerve fiber layer (RNFL) and optic disc measurements. RESULTS Thirty healthy participants (60 eyes) and 38 glaucoma patients (76 eyes) were included in the study. RTVue reproducibility was good in both healthy participants and patients. For average RNFL thickness, the intraclass correlation coefficients in healthy eyes and patient eyes were 0.97 whereas for rim area they were 0.97 and 0.96, respectively. The correlation between RTVue and Stratus measurements generally was good, especially for average RNFL thickness (healthy eyes and patient eyes, r2 = 0.82 and 0.86, respectively) and rim volume (healthy eyes and patient eyes, r2 = 0.78 and 0.76, respectively). Bland-Altman plots showed good agreement between the instruments, with better agreement for average RNFL thickness (95% limits of agreement in healthy eyes and patient eyes, ?8.6 to 12 µm and ?5.6 to ?14.8 µm, respectively) than optic disc parameters. Cup-to-disc ratio 95% limits of agreement in healthy eyes and patient eyes were ?0.3 to 0.4 and ?0.2 to 0.3, respectively. Optic disc measurements with RTVue were smaller than those with Stratus OCT (eg, disc area was on average 0.4 mm2 smaller and rim area was 0.3 mm2 smaller with RTVue). CONCLUSIONS Reproducibility of RTVue RNFL and optic disc measurements was excellent in both groups. The level of agreement between RTVue and Stratus measurements suggests that RTVue has the potential to detect glaucomatous structural changes. PMID:19268891

González-García, Alberto O.; Vizzeri, Gianmarco; Bowd, Christopher; Medeiros, Felipe A.; Zangwill, Linda M.; Weinreb, Robert N.

2009-01-01

102

Digital stereo-optic disc image analyzer for monitoring progression of glaucoma  

NASA Astrophysics Data System (ADS)

This paper describes an automated 3-D surface recovery algorithm for consistent and quantitative evaluation of the deformation in the ONH (optic nerve head). Additional measures, such as the changes in the volume of the cup and the disc as an improvement to the traditional cup to disc ratios, can thus be developed for longitudinal follow-up study of a patient. We propose an automated computerized technique for stereo pair registration and surface visualization of the ONH. Power cepstrum and zero mean cross correlation are embedded in the registration and a 3-D surface recovery technique is proposed. Preprocessing, as well as an overall registration, is performed upon stereo pairs. Then a coarse to fine feature matching strategy is used to reduce the ambiguity in finding the conjugate pair of the same point within the constraints of the epipolar plane. A cubic B-spline interpolation smooths the representation of the ONH obtained, while superimposition of features such as blood vessels is added. Studies show high correlation between traditional cup/disc measures derived from manual segmentation by ophthalmologists and computer generated cup/disc volume ratio. Such longitudinal studies over a large population of glaucoma patients are currently in progress for validation of the surface recovery algorithm.

Corona, Enrique; Mitra, Sunanda; Wilson, Mark P.; Soliz, Peter

2002-05-01

103

Displacement of foveal area toward optic disc after macular hole surgery with internal limiting membrane peeling  

PubMed Central

Purpose To determine whether there is a displacement of the fovea toward the optic disc after successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling. Methods The medical records of 54 eyes of 53 patients that had undergone pars plana vitrectomy with ILM peeling and gas or air tamponade for an idiopathic MH were evaluated. Spectral-domain optical coherence tomography (OCT) had been performed before and >6 months after the surgery. The preoperative distances between the center of the MH and the optic disc (MH-OD), center of the MH and the bifurcation or crossing of retinal vessels (MH-RV) were measured in the OCT images. In addition, the postoperative distance between the center of the fovea and optic disc (F-OD) and the center of the fovea and the same bifurcation or crossing of retinal vessels (F-RV) were measured in the OCT images. Results The F-OD was 2.67±0.33 disc diameters (DD), which was significantly shorter than that of the MH-OD of 2.77±0.33 DD (P<0.001). The F-RV was also significantly shorter than the MH-RV on the inner nasal area (from 0.85±0.16DD to 0.79±0.15DD; P<0.001), the inner temporal area (from 0.82±0.15DD to 0.77±0.14DD; P<0.001), and outer nasal area (from 1.70±0.31DD to 1.65±0.32DD; P<0.001), but it was significantly longer than the MH-RV in the outer temporal area (from 1.65±0.29DD to 1.68±0.29DD; P<0.001). Conclusion Our results showed that successful closure of a MH by vitrectomy with ILM peeling and gas tamponade leads to a displacement of the center of the macula toward the optic disc. PMID:23703632

Kawano, K; Ito, Y; Kondo, M; Ishikawa, K; Kachi, S; Ueno, S; Iguchi, Y; Terasaki, H

2013-01-01

104

Posterior staphyloma is related to optic disc morphology and the location of visual field defect in normal tension glaucoma patients with myopia.  

PubMed

PurposeTo determine the morphologic features of the optic disc and the location of visual field (VF) defect in relation to posterior staphyloma in normal tension glaucoma (NTG) eyes with myopia.MethodsOne hundred and thirty-four NTG patients with myopia were enrolled. B-scan ultrasonography was performed in enrolled patients. Disc tilt ratio, disc torsion, and area of peripapillary atrophy were measured from disc photographs. Patients were classified according to the presence of posterior staphyloma and its location: staphyloma involving the optic disc, staphyloma involving either the supero-temporal side of the optic disc or the infero-temporal side of the optic disc. The relationship between the location of the posterior staphyloma and that of the VF defect was analyzed.ResultsAmong 134 eyes, 74 eyes (55.2%) had posterior staphyloma on B-scan ultrasonography. Mean torsion degree was significantly greater in eyes with staphyloma involving the temporal side of the optic disc (19.78±18.00°) compared with eyes with staphyloma involving the optic disc (4.65±4.92°, P=0.001). The frequency of the location of VF damage differed significantly between eyes with staphyloma involving the supero-temporal side and those involving the infero-temporal side of the optic disc (P=0.008), which was not significant in eyes with staphyloma involving the optic disc (P=0.813).ConclusionsOptic disc torsion was a prominent finding in myopic NTG eyes when posterior staphyloma was located temporal to the optic disc. The location of posterior staphyloma was related to the direction of disc torsion and the location of VF defect. PMID:25376120

Park, H-Yl; Jung, Y; Park, C K

2015-03-01

105

Are the broad optical Balmer lines in PG 1613+658 from the central accretion disc?  

NASA Astrophysics Data System (ADS)

In this letter, we report on the positive correlations between the broad-line width and broad-line flux for the broad Balmer lines of the active galactic nucleus (AGN) PG 1613+658, which has been observed for a long time. Rather than the expected negative correlations that come with the widely accepted virialization assumption for AGN broad emission-line regions (BLRs), the positive correlations indicate very different BLR structures of PG 1613+658 from the commonly considered BLR structures that are dominated by the equilibrium between radiation pressure and gas pressure. Therefore, it is preferable to assume that the observed broad single-peaked optical Balmer lines of PG 1613+658 originate from the accretion disc, because the mainly gravity-dominated disc-like BLRs with radial structures have few effects from radiation pressure.

Zhang, Xue-Guang

2015-02-01

106

Reduction of Interlayer Crosstalk of Multilayer Optical Disc by Using Phase-Diversity Homodyne Detection  

NASA Astrophysics Data System (ADS)

We theoretically and experimentally studied the effects of phase-diversity homodyne detection on the interlayer crosstalk of a multilayer optical disc by comparison with those of conventional intensity detection. From analytical studies, we clarified the differences in interlayer crosstalk of both detections. Interlayer crosstalk consists of two noises, the intensity of the stray light N1 and the interference between the signal and stray light N2. The noise N1, which is dominant between these two, drastically decreases with layer spacing in phase-diversity homodyne detection owing to mismatch in the phase distribution between reference and stray light compared with that in intensity detection. Simulations and experiments on a dual-layer Blu-ray DiscTM having a layer spacing less than 10 µm demonstrated that phase-diversity homodyne detection provided higher tolerance to interlayer crosstalk than the conventional intensity detection.

Ide, Tatsuro; Osawa, Kentaro; Mikami, Hideharu; Watanabe, Koichi

2012-08-01

107

On the optical--infra-red continuum emission from equatorial discs of supergiant B[e] stars  

E-print Network

Two models of the circumstellar disc around supergiant B[e] stars are discussed: an equatorial wind model produced by wind bi-stability, and a Keplerian viscous disc model. Both models are successful in providing a site for dust formation once they have cooled sufficiently. However, the optical--infra-red continuum is calculated and it is found that both models have significant trouble in accounting for observations. In particular the optical--near-IR emission is accounted for, but the dust emission is underestimated by at least an order of magnitude. Variations in the structure of the models (the temperature variation with radius, the density structure and the dust opacity) are investigated to assess how (in)appropriate the standard models are for supergiant B[e] star discs. Changing the temperature structure, and making simple dust opacity changes within the disc has little effect on the resultant continuum emission. By altering the density structure of the discs, the continuum may be accounted for by both models: the equatorial wind model requires a very flat density profile which is impossible to explain with any accelerating wind, and the viscous disc model's density structure is required to fall off less steeply with radius than would have been expected, although this may be explained from consideration of viscous processes in the disc. It is recognised that both theoretical interpretations have difficulties and unsolved problems.

John M. Porter

2002-11-20

108

Eccentricity Compensation Mechanism for Improving Reliability of Removable Performance in Near-Field Optical Disc Drive System  

NASA Astrophysics Data System (ADS)

In this paper, we propose the eccentricity-compensating actuator mechanism for near-field (NF) optical disc drives. In this proposed dual-stage compensating actuator mechanism, the disc-spindle unit is actuated instead of the solid immersion lens (SIL) along the tracking axis to cancel out an eccentricity less than 20 µmpp (pp: peak to peak), which is the required criterion for NF discs of 160 nm track pitch. As a result, the proposed method enables the decrease in the required residual tracking error to lower than the criteria of 4.5 nm in NF optical disc drive (ODD) even when using the tracking servo of moderate performance. The proposed active eccentricity compensation method can be effective and applicable to dealing with the eccentricity problem in NF ODD, which we verified experimentally.

Kim, Sunmin; Ishimoto, Tsutomu; Nakaoki, Ariyoshi; Kawakubo, Osamu

2008-07-01

109

Genome-wide association identifies ATOH7 as a major gene determining human optic disc size.  

PubMed

Optic nerve assessment is important for many blinding diseases, with cup-to-disc ratio (CDR) assessments commonly used in both diagnosis and progression monitoring of glaucoma patients. Optic disc, cup, rim area and CDR measurements all show substantial variation between human populations and high heritability estimates within populations. To identify loci underlying these quantitative traits, we performed a genome-wide association study in two Australian twin cohorts and identified rs3858145, P=6.2x10(-10), near the ATOH7 gene as associated with the mean disc area. ATOH7 is known from studies in model organisms to play a key role in retinal ganglion cell formation. The association with rs3858145 was replicated in a cohort of UK twins, with a meta-analysis of the combined data yielding P=3.4x10(-10). Imputation further increased the evidence for association for several SNPs in and around ATOH7 (P=1.3x10(-10) to 4.3x10(-11), top SNP rs1900004). The meta-analysis also provided suggestive evidence for association for the cup area at rs690037, P=1.5x10(-7), in the gene RFTN1. Direct sequencing of ATOH7 in 12 patients with optic nerve hypoplasia, one of the leading causes of blindness in children, revealed two novel non-synonymous mutations (Arg65Gly, Ala47Thr) which were not found in 90 unrelated controls (combined Fisher's exact P=0.0136). Furthermore, the Arg65Gly variant was found to have very low frequency (0.00066) in an additional set of 672 controls. PMID:20395239

Macgregor, Stuart; Hewitt, Alex W; Hysi, Pirro G; Ruddle, Jonathan B; Medland, Sarah E; Henders, Anjali K; Gordon, Scott D; Andrew, Toby; McEvoy, Brian; Sanfilippo, Paul G; Carbonaro, Francis; Tah, Vikas; Li, Yi Ju; Bennett, Sonya L; Craig, Jamie E; Montgomery, Grant W; Tran-Viet, Khanh-Nhat; Brown, Nadean L; Spector, Timothy D; Martin, Nicholas G; Young, Terri L; Hammond, Christopher J; Mackey, David A

2010-07-01

110

New optical architecture for holographic data storage system compatible with Blu-ray Disc™ system  

NASA Astrophysics Data System (ADS)

A new optical architecture for holographic data storage system which is compatible with a Blu-ray Disc™ (BD) system is proposed. In the architecture, both signal and reference beams pass through a single objective lens with numerical aperture (NA) 0.85 for realizing angularly multiplexed recording. The geometry of the architecture brings a high affinity with an optical architecture in the BD system because the objective lens can be placed parallel to a holographic medium. Through the comparison of experimental results with theory, the validity of the optical architecture was verified and demonstrated that the conventional objective lens motion technique in the BD system is available for angularly multiplexed recording. The test-bed composed of a blue laser system and an objective lens of the NA 0.85 was designed. The feasibility of its compatibility with BD is examined through the designed test-bed.

Shimada, Ken-ichi; Ide, Tatsuro; Shimano, Takeshi; Anderson, Ken; Curtis, Kevin

2014-02-01

111

Identification of Optic Disc Elevation and the Crescent Sign Using Point-of-Care Ocular Ultrasound in Children.  

PubMed

Point-of-care ocular ultrasound has been used to detect papilledema. In previous studies, investigators have evaluated only optic nerve sheath diameter as a screen for increased intracranial pressure. In this series of 4 children, we demonstrate 2 additional optic nerve abnormalities using point-of-care ocular ultrasound: optic disc elevation and the crescent sign. Assessing the optic nerve for each of these 3 findings may assist the examiner in detecting papilledema. PMID:25831036

Marchese, Ronald F; Mistry, Rakesh D; Scarfone, Richard J; Chen, Aaron E

2015-04-01

112

The role of optical coherence tomography raster imaging as a valuable diagnostic tool in the differential between optic disc hemorrhage and vitreopapillary traction.  

PubMed

An acute presentation of an optic disc hemorrhage can indicate true optic nerve head damage or can be a result of tractional forces on the vitreopapillary interface. An isolated optic disc hemorrhage secondary to vitreopapillary traction (VPT) can mimic the clinical presentation of a glaucomatous process or that of an underlying ocular or systemic condition. This article highlights the use of spectral domain optical coherence tomography (SD-OCT) 5 line raster (5LR) in differentiating true optic disc hemorrhages from those as a result of tractional forces. Two examples are given of patients presenting to our clinic with unilateral optic disc hemorrhages and various underlying disease processes as risk factors. With the use of SD-OCT 5LR imaging, VPT was implicated as the cause of the disc hemorrhages in both patients. Although this imaging tool alone is not enough to rule out a disease process such as glaucoma or prevent the need for additional diagnostic testing, SD-OCT 5LR is a noninvasive and valuable clinical tool in distinguishing VPT from other etiologies of an optic nerve hemorrhage. PMID:23198516

Wong, Anna; Kokolakis, Pagona; Rodriguez, Alexis; Pearcy-Baluyot, Mischelle

2012-11-01

113

Interlayer crosstalk reduction of a multilayer Blu-ray Disc using a grating in a three beam optical system.  

PubMed

In multilayer optical discs, light reflected by out-of-focus layers, which we call interlayer crosstalk, causes the tracking error signal to fluctuate, making the readout signal unstable. We previously proposed a novel method to use a grating along the optical axis in the return path of a pickup to suppress the fluctuation of a differential push-pull (DPP) signal. We develop a pickup and evaluate its performance to stabilize the DPP signal experimentally. DPP signal fluctuation is suppressed to one-third (6% to 2%), and also satisfactory readout jitters (about 8%) are obtained for a triple-layer Blu-ray Disc (BD), which demonstrate the validity of this method to reduce interlayer crosstalk of multilayer optical discs. PMID:20411010

Ide, Tatsuro; Kimura, Shigeharu; Tatsu, Eriko; Kurokawa, Takahiro; Watanabe, Koichi; Anzai, Yumiko; Shintani, Toshimichi

2010-04-20

114

Development of Integrated Small-Form-Factor Optical Pickup with Blu-ray Disc Specification  

NASA Astrophysics Data System (ADS)

In this study, a small-form-factor optical pickup (SFFOP), corresponding to the Blu-ray disc (BD) specifications has been developed. The developed SFFOP is composed of an integrated optical pickup and a swing-arm-type actuator. The integrated optical pickup has been developed in the form of an array using wafer-level fabrication technology. The developed SFFOP is composed of the fundamental optics which yields a numerical aperture (NA) of 0.85 and uses a blue laser diode having a short wavelength of 407 nm and a silicon optical bench, which consists of a laser diode, a photodiode and several mounts for the laser diode, an objective lens and mirrors. The micro objective lens is bonded to the lens holder on the SFFOP by an active alignment using a modified Mach-Zehnder interferometer. Also, a static focus error signal was detected to assemble a polarized holographic optical element. Through the measurement of the focus error signal with a swing-arm-type actuator, which was developed for the SFFOP, it is estimated that the developed SFFOP satisfies the BD specifications with the balance of the focus error signal below 10%.

Kang, Sung?Mook; Lee, Jin?Eui; Kim, Wan?Chin; Park, No?Cheol; Park, Young?Pil; Cho, Eun?Hyoung; Sohn, Jin?Seung; Suh, Sung?Dong

2006-08-01

115

Long-term outcomes of pars plana vitrectomy without internal limiting membrane peeling for optic disc pit maculopathy  

PubMed Central

Purpose To evaluate the results of surgical treatment of maculopathy secondary to congenital optic pit anomaly with pars plana vitrectomy (PPV), endolaser to the temporal edge of the optic disc and C3F8 tamponade without internal limiting membrane (ILM) peeling. Patients and methods Thirteen eyes of 12 patients with serous macular detachment and/or macular retinoschisis secondary to congenital optic disc pit (ODP) were included in the study. All eyes underwent PPV, posterior hyaloid removal, endolaser photocoagulation on the temporal margin of the optic disc and 12% C3F8 gas tamponade. Anatomic success and functional outcome determined retrospectively by optical coherence tomography and measurement of best corrected visual acuity (BCVA), respectively were the main outcome parameters. Results Two lines or more improvement in BCVA was obtained in 11 eyes and 6 of these eyes had 20/40 or better BCVA at the final visit. Subretinal or intraretinal fluid was completely resorbed postoperatively in 12 eyes but a little intraretinal fluid persisted in one eye at the 16-month follow-up. Better visual improvement was observed in patients treated by earlier surgical intervention. Conclusion PPV, C3F8 gas tamponade and endolaser to the optic disc margin without ILM peeling may yield favourable results in the treatment of ODP maculopathy. PMID:24037231

Avci, R; Yilmaz, S; Inan, U U; Kaderli, B; Kurt, M; Yalcinbayir, O; Yildiz, M; Yucel, A

2013-01-01

116

Triple-write One-lens Optical Pickup for Blu-ray Disc\\/DVD\\/CD Supporting 4x Blu-ray Read\\/Write  

Microsoft Academic Search

Blu-ray disc (BD)\\/digital versatile disc (DVD)\\/compact disc (CD) compatible optical pickup supporting Blu-ray 4times read\\/write has been developed. To achieve 4times speed for BD, a one-lens-type objective lens was adopted to ensure stability for high-speed tracking servo control. Optical system, signal characteristics, and actuator vibration characteristics of the developed pickup are presented.

F. Issiki; N. Maeda; K. Kimura; H. Suenaga; T. Kurokawa

2007-01-01

117

Optical Spectroscopic Monitoring of Parachute Yarn Aging  

SciTech Connect

Optical spectroscopic techniques were evaluated as nondestructive monitors of the aging of parachutes in nuclear weapons. We analyzed thermally aged samples of nylon and Kevlar webbing by photoluminescence spectroscopy and reflection spectroscopy. Infrared analysis was also performed to help understand the degradation mechanisms of the polymer materials in the webbing. The photoluminescence and reflection spectra were analyzed by chemometric data treatment techniques to see if aged-induced changes in the spectra correlated to changes in measured tensile strength. A correlation was found between the shapes of the photoluminescent bands and the measured tensile strengths. Photoluminescent spectra can be used to predict the tensile strengths of nylon and Kevlar webbing with sufficient accuracy to categorize the webbing sample as above rated tensile strength, marginal or below rated tensile strength. The instrumentation required to perform the optical spectroscopic measurement can be made rugged, compact and portable. Thus, optical spectroscopic techniques offer a means for nondestructive field monitoring of parachutes in the enduring stockpile/

Tallant, D.R.; Garcia, M.J.; Simpson, R.L.; Behr, V.L.; Whinery, L.D.; Peng, L.W.

1999-04-01

118

Comparing acromegalic patients to healthy controls with respect to intraocular pressure, central corneal thickness, and optic disc topography findings  

PubMed Central

Aims: The aim was to compare the intraocular pressure (IOP), central corneal thickness (CCT), and optic disc topography findings of biochemically controlled acromegalic patients and the control group and to evaluate the effect of the duration of acromegaly and serum growth hormone and insulin-like growth factor-1 (IGF-1) levels on these ocular parameters. Materials and Methods: IOP measurement with Goldmann applanation tonometry, CCT measurement with ultrasonic pachymetry, and topographic analysis with Heidelberg retinal tomograph III were performed on 35 biochemically controlled acromegalic patients and 36 age- and gender-matched controls. Results: Mean IOP and CCT were 14.7 ± 2.9 mmHg and 559.5 ± 44.9 ?m in the acromegaly patients and 13.0 ± 1.6 mmHg and 547.1 ± 26.7 ?m in controls (P = 0.006 and P = 0.15, respectively). A significant moderate correlation was found between the duration of acromegaly and CCT (r = 0.391) and IOP (r = 0.367). Mean retinal nerve fiber layer (RNFL) thickness was significantly lower in the acromegalic patients (0.25 ± 0.05 mm) as compared to controls (0.31 ± 0.09 mm) (P = 0.01). A significant moderate correlation was detected between IGF-1 level and disc area (r = 0.362), cup area (r = 0.389) and cup volume (r = 0.491). Conclusion: Biochemically controlled acromegalic patients showed significantly higher CCT and IOP levels and lower RNFL thickness compared to healthy controls and the duration of disease was correlated with CCT and IOP levels. PMID:25230958

Sen, Emine; Tutuncu, Yasemin; Elgin, Ufuk; Balikoglu-Yilmaz, Melike; Berker, Dilek; Aksakal, F. Nur; Ozturk, Faruk; Guler, Serdar

2014-01-01

119

Meta-analysis of Genome-Wide Association Studies Identifies Novel Loci Associated With Optic Disc Morphology.  

PubMed

Primary open-angle glaucoma is the most common optic neuropathy and an important cause of irreversible blindness worldwide. The optic nerve head or optic disc is divided in two parts: a central cup (without nerve fibers) surrounded by the neuroretinal rim (containing axons of the retinal ganglion cells). The International Glaucoma Genetics Consortium conducted a meta-analysis of genome-wide association studies consisting of 17,248 individuals of European ancestry and 6,841 individuals of Asian ancestry. The outcomes of the genome-wide association studies were disc area and cup area. These specific measurements describe optic nerve morphology in another way than the vertical cup-disc ratio, which is a clinically used measurement, and may shed light on new glaucoma mechanisms. We identified 10 new loci associated with disc area (CDC42BPA, F5, DIRC3, RARB, ABI3BP, DCAF4L2, ELP4, TMTC2, NR2F2, and HORMAD2) and another 10 new loci associated with cup area (DHRS3, TRIB2, EFEMP1, FLNB, FAM101, DDHD1, ASB7, KPNB1, BCAS3, and TRIOBP). The new genes participate in a number of pathways and future work is likely to identify more functions related to the pathogenesis of glaucoma. PMID:25631615

Springelkamp, Henriët; Mishra, Aniket; Hysi, Pirro G; Gharahkhani, Puya; Höhn, René; Khor, Chiea-Chuen; Cooke Bailey, Jessica N; Luo, Xiaoyan; Ramdas, Wishal D; Vithana, Eranga; Koh, Victor; Yazar, Seyhan; Xu, Liang; Forward, Hannah; Kearns, Lisa S; Amin, Najaf; Iglesias, Adriana I; Sim, Kar-Seng; van Leeuwen, Elisabeth M; Demirkan, Ayse; van der Lee, Sven; Loon, Seng-Chee; Rivadeneira, Fernando; Nag, Abhishek; Sanfilippo, Paul G; Schillert, Arne; de Jong, Paulus T V M; Oostra, Ben A; Uitterlinden, André G; Hofman, Albert; Zhou, Tiger; Burdon, Kathryn P; Spector, Timothy D; Lackner, Karl J; Saw, Seang-Mei; Vingerling, Johannes R; Teo, Yik-Ying; Pasquale, Louis R; Wolfs, Roger C W; Lemij, Hans G; Tai, E-Shyong; Jonas, Jost B; Cheng, Ching-Yu; Aung, Tin; Jansonius, Nomdo M; Klaver, Caroline C W; Craig, Jamie E; Young, Terri L; Haines, Jonathan L; MacGregor, Stuart; Mackey, David A; Pfeiffer, Norbert; Wong, Tien-Yin; Wiggs, Janey L; Hewitt, Alex W; van Duijn, Cornelia M; Hammond, Christopher J

2015-03-01

120

Optic disc topography in Malay patients with normal-tension glaucoma and primary open-angle glaucoma  

PubMed Central

Background There are limited data concerning the optic disc topography in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG) patients living in Southeast Asian countries. This study aims to compare optic disc parameters in patients with NTG and POAG in Malaysia and to discuss the results in comparison with studies of NTG and POAG in other Asian countries. Methods This prospective cross-sectional study was performed in two hospitals with glaucoma service in Malaysia from 2010 to 2012. Seventy-seven patients of Malay ethnicity were enrolled in this study, including 32 NTG patients and 45 POAG patients. Using the Heidelberg Retinal Tomograph III, we measured optic disc area, cup area, rim area, cup volume, rim volume, cup-to-disc area ratio, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area. Results The eyes for NTG patients had significantly larger optic disc areas (2.65 [standard deviation, 0.41] vs 2.40 [standard deviation, 0.36] mm2, respectively; P=0.006) and cup areas (1.54 [standard deviation, 0.43] vs 1.32 [standard deviation, 0.40] mm2, respectively; P=0.027) compared with the eyes of POAG patients. Comparison of the other parameters between the two groups revealed no significant difference (P>0.050). The moderate and severe NTG patients showed significantly deeper cups and larger disc and cup areas when compared with the moderate and severe POAG patients (P<0.050). Conclusion The NTG patients in this study have notably larger optic disc and cup areas than the POAG patients. Our observations are consistent with those reported in studies of NTG and POAG patients in Korea. The deeper cups and larger disc and cup areas may serve as indicators of severity when comparing NTG with POAG. However, these findings require verification with IOP and visual field results. PMID:25540578

Adlina, Abdul Rahim; Alisa-Victoria, Koh; Shatriah, Ismail; Liza-Sharmini, Ahmad Tajudin; Ahmad, Mt Saad

2014-01-01

121

Structural and Optical Properties of Disc-in-Wire InGaN/GaN LEDs.  

PubMed

This study examines the role of the microstructure and optical properties of InGaN/GaN nanowire LED structures on Si(111) having different nanowire coverages. Cathodoluminescence (CL) measurements show that all samples exhibit broad emission around the intended energy, 1.95 eV (635 nm). While the absolute emission intensity is hard to compare for CL measurement, the bandgap emission (?3.4 eV) coming from the GaN root is more pronounced as coverage of nanowires decreases, which has less coalescence formation. The width of the emission peak is likely due to variations in the morphology of the InGaN discs within the wires, as faceted layers with different thicknesses and quantum dots are observed by transmission electron microscopy. Nonepitaxial six-fold symmetric lateral branching, called "nanocrowns," emanate from stacking faults within the active regions. These features likely reduce optical emission as a result of grain boundaries between the nanocrown and nanowire. PMID:25658444

Yan, Lifan; Jahangir, Shafat; Wight, Scott A; Nikoobakht, Babak; Bhattacharya, Pallab; Millunchick, Joanna M

2015-03-11

122

A Multilayered Blu-Ray Disc readout technique with an optical longitudinal filter for reducing interlayer crosstalk in a three-beam optical system  

Microsoft Academic Search

A Multilayered Blu-ray Disc (BD) readout technique-using an optical longitudinal filter (OLF) and differential push-pull (DPP)-to reduce interlayer crosstalk was demonstrated. DPP signal fluctuation was suppressed to one-third (6% to 2%), and satisfactory readout jitters (about 8%) were obtained for a triple-layered BD.

Tatsuro Ide; Shigeharu Kimura; Eriko Tatsu; Takahiro Kurokawa; Koichi Watanabe; Yumiko Anzai; Toshimichi Shintani

2009-01-01

123

Super-Resolution Optical Disc with Radial Density Increased by Narrowed Track Pitch Corresponding to Diffraction Limit  

NASA Astrophysics Data System (ADS)

In-Sb-based super-resolution near-field structure read-only-memory discs with radial density increased by introducing a narrow track pitch corresponding to the diffraction limit of an optical system were developed. Using an optical system with a laser diode with a wavelength of 405 nm and an objective lens with a numerical aperture of 0.85, we confirmed that differential phase detection (DPD) could detect track errors from disc samples recorded random data including a minimum pit length of 75 nm in a 240 nm track period. It has higher capability of track error detection than push-pull detection at a narrowed track pitch. Moreover, bit error rates satisfying the criterion of 3.0×10-4 were experimentally obtained for 66.7-GB-capacity disc samples with a 240 nm track pitch through signal processing with the partial response maximum likelihood of the (1,2,2,1)-type, by applying DPD to tracking servo control. The feasibility of increasing the track density of the Blu-ray DiscTM physical format by 1.33 times was indicated.

Nakai, Kenya; Ohmaki, Masayuki; Takeshita, Nobuo; Hyot, Bérangère; André, Bernard; Poupinet, Ludovic; Shima, Takayuki

2013-09-01

124

Optical-to-virial velocity ratios of local disc galaxies from combined kinematics and galaxy-galaxy lensing  

NASA Astrophysics Data System (ADS)

In this paper, we measure the optical-to-virial velocity ratios Vopt/V200c of disc galaxies in the Sloan Digital Sky Survey (SDSS) at a mean redshift of = 0.07 and with stellar masses 109 < M* < 1011 M?. Vopt/V200c, the ratio of the circular velocity measured at the optical radius of the disc (˜10 kpc) to that at the virial radius of the dark matter halo (˜150 kpc), is a powerful observational constraint on disc galaxy formation. It links galaxies to their dark matter haloes dynamically and constrains the total mass profile of disc galaxies over an order of magnitude in length scale. For this measurement, we combine Vopt derived from the Tully-Fisher relation (TFR) from Reyes et al. with V200c derived from halo masses measured with galaxy-galaxy lensing. In anticipation of this combination, we use similarly selected galaxy samples for both the TFR and lensing analysis. For three M* bins with lensing-weighted mean stellar masses of 0.6, 2.7 and 6.5 × 1010 M?, we find halo-to-stellar mass ratios M200c/M* = 41, 23 and 26, with 1? statistical uncertainties of around 0.1 dex, and Vopt/V200c = 1.27 ± 0.08, 1.39 ± 0.06 and 1.27 ± 0.08 (1?), respectively. Our results suggest that the dark matter and baryonic contributions to the mass within the optical radius are comparable, if the dark matter halo profile has not been significantly modified by baryons. The results obtained in this work will serve as inputs to and constraints on disc galaxy formation models, which will be explored in future work. Finally, we note that this paper presents a new and improved galaxy shape catalogue for weak lensing that covers the full SDSS Data Release 7 footprint.

Reyes, R.; Mandelbaum, R.; Gunn, J. E.; Nakajima, R.; Seljak, U.; Hirata, C. M.

2012-10-01

125

Morphology of Optic Disc Through Heidelberg Retina Tomograph in Retinal Vein Occlusions Alone or in Combination with Primary Open Angle Glaucoma§  

PubMed Central

Purpose: To evaluate the morphology of optic discs in eyes suffering from retinal vein occlusion (RVO) alone or in combination with primary open-angle glaucoma (POAG). Methods: Prospective, observational study. 48 consecutive patients were enrolled, 30 with unilateral RVO diagnosis, 18 with unilateral retinal vein occlusion (RVO) associated with POAG. We divided RVOs on the basis of occlusion site: arterio-venous crossing (AV-RVO), optic cup (OC-RVO), optic nerve (ON-RVO) with head nerve swelling (ONHS-RVO) or without it (NONHS-RVO). A control group of 25 patients who were sex and age matched was selected. Results: Comparing the fellow eyes of the patients with RVO and control healthy eyes, no differences emerged in cup/disc ratio but they came out for the HRT values in Rim Area, cup shape measure and height variation contour (p<0.05). The most frequent occlusion site was at the level of an arteriovenous crossing in patients not suffering from POAG (36.7%) and at the level of the optic cup in patients with RVO and POAG (50%). In the RVO group without POAG, the OC-RVO subgroup has shown an higher cup area (0.366±0.094) and cup/disc area ratio (0.184±0.063), a lower rim volume (0.374±0.021) and a different cup shape measure (-0.221±0.066) (p<0.05) compared with the AV and NONHS sites. Compared with NONHS group differences emerged also for the fibres parameters and in the height variation contour (0.346±0.081). Also in the RVO group with POAG significant differences (p<0.05) have been surveyed between OC-RVO and other occlusion sites in cup area (0.119±0.029), cup/disc area ratio (0.532±0.09), rim volume (0.374±0.07), cup/shape measure (-0.079±0.013). Conclusions: Classification of the analyzed parameters on the basis of the occlusion site provides a basis for which clinical decisions and research on causal factors in future studies can be based on. PMID:23961303

Actis, Alessandro Guido; Belli, Luca; Dall’orto, Laura; Penna, Rachele; Brogliatti, Beatrice; Rolle, Teresa

2013-01-01

126

Age related reduction of T1rho and T2 magnetic resonance relaxation times of lumbar intervertebral disc  

PubMed Central

This report aims to study the age related T1rho and T2 relaxation time changes in lumbar intervertebral disc. Lumbar sagittal magnetic resonance imaging (MRI) was performed with a 3 Tesla scanner in 52 subjects. With a spin-lock frequency of 500 Hz, T1rho was measured using a rotary echo spin-lock pulse embedded in a 3D balanced fast field echo sequence. A multi-echo turbo spin echo sequence was used for T2 mapping. Regions-of-interest were drawn over the T1rho and T2 maps, including nucleus pulposus and annulus fibrosus. For L1/2-L4/5 discs, results showed the age associated reduction of T1rho of nucleus pulposus had a of slope of –1.06, the reduction of T2 of nucleus pulposus had a slope of –1.47, the reduction of T1rho of annulus fibrosus had a slope of –0.25, and the reduction of T2 of annulus fibrosus had a slope of –0.18, with all the slopes significantly non-zero. In nucleus pulposus the slope of T2 was slightly steeper than that of T1rho (P=0.085), while in annulus fibrosus the slope of T1rho was slightly steeper than that of T2 (P=0.31). We conclude that significant age related reduction of T1rho and T2 magnetic resonance relaxation times of lumbar intervertebral disc was observed, however, the relative performances of T1rho vs. T2 were broadly similar. PMID:25202661

Griffith, James F.; Leung, Jason C. S.; Yuan, Jing

2014-01-01

127

Evolution from protoplanetary to debris discs: the transition disc around HD 166191  

NASA Astrophysics Data System (ADS)

HD 166191 has been identified by several studies as hosting a rare and extremely bright warm debris disc with an additional outer cool disc component. However, an alternative interpretation is that the star hosts a disc that is currently in transition between a full gas disc and a largely gas-free debris disc. With the help of new optical to mid-infrared (IR) spectra and Herschel imaging, we argue that the latter interpretation is supported in several ways: (i) we show that HD 166191 is comoving with the ˜4-Myr-old Herbig Ae star HD 163296, suggesting that the two have the same age; (ii) the disc spectrum of HD 166191 is well matched by a standard radiative transfer model of a gaseous protoplanetary disc with an inner hole and (iii) the HD 166191 mid-IR silicate feature is more consistent with similarly primordial objects. We note some potential issues with the debris disc interpretation that should be considered for such extreme objects, whose lifetime at the current brightness is much shorter than the stellar age, or in the case of the outer component requires a mass comparable to the solid component of the solar nebula. These aspects individually and collectively argue that HD 166191 is a 4-5 Myr old star that hosts a gaseous transition disc. Though it does not argue in favour of either scenario, we find strong evidence for 3-5 ?m disc variability. We place HD 166191 in context with discs at different evolutionary stages, showing that it is a potentially important object for understanding the protoplanetary to debris disc transition.

Kennedy, G. M.; Murphy, S. J.; Lisse, C. M.; Ménard, F.; Sitko, M. L.; Wyatt, M. C.; Bayliss, D. D. R.; DeMeo, F. E.; Crawford, K. B.; Kim, D. L.; Rudy, R. J.; Russell, R. W.; Sibthorpe, B.; Skinner, M. A.; Zhou, G.

2014-03-01

128

The mass distribution in early-type disc galaxies: declining rotation curves and correlations with optical properties  

Microsoft Academic Search

We present rotation curves for 19 early-type disc galaxies (S0-Sab). The galaxies span a B-band absolute magnitude range from -17.5 to -22, but the majority have a high luminosity with MB < -20. Rotation velocities are measured from a combination of HI velocity fields and long-slit optical emission line spectra along the major axis; the resulting rotation curves probe the

E. Noordermeer; J. M. van der Hulst; R. Sancisi; R. S. Swaters; T. S. van Albada

2007-01-01

129

Resonance measurements techniques of optical whispering gallery mode mini-disc resonators for microwave photonics applications  

NASA Astrophysics Data System (ADS)

The aim of this work is to compare advantages and disadvantages of different techniques for coupling a mini-discoptical- resonator to determine quality factor of its resonance. Optical fiber coupled to a resonator consists in a mini disc with whispering gallery modes at its circumference. We choose to work with three materials and design compact miniresonators. Fused silica is found to be suitable for these applications thanks to its hardness in the range 6-7 and the behavior to mechanical shocks, despite its sensitivity to water pollution. With its tetragonal crystal and a good behavior with risk of water pollution, Calcium fluoride is a good candidate despite sensitivity to mechanical shocks. Magnesium fluoride is the third material used. As a critical step, taper coupling is set with a 20nm resolution positioning system. Miniresonator is excited from a system equipped with a tunable laser diode with a tunability from 1490 to 1640 nm and a linewidth narrower than 300kHz. Light is coupled into the microsphere either from glass or fiber prism or with fiber taper via evanescent field. We have also used a single frequency 660nm laser diode with a linewidth narrower than 100kHz which can be tuned about 10pm to test a single resonant peak. Both sources are used with either a tapered fiber or a filed fiber. Resonance is observed and quality factor of the resonators is found to be in the range of 108.

Salzenstein, Patrice; Jelínek, Michal; Chembo, Yanne K.; Pogurmiskiy, Maxim; Tavernier, Hervé; Volyanskiy, Kirill; Phan Huy, Kien; Chauvet, Mathieu; Larger, Laurent; Kubecek, Václav

2011-06-01

130

Measurement of optic disc size: equivalence of methods to correct for ocular magnification  

PubMed Central

AIMS—To compare methods available to correct the magnification of images that result from the optics of the eye and identify errors, and source of error, of the methods.?METHODS—11 methods were applied to ocular biometry data from three independent cohorts. Each method was compared with the method of Bennett, which uses most biometric data. The difference between each method and Bennett's is the "error" of the method. The relation between the error and axial length, ametropia, and keratometry was explored by linear regression analysis.?RESULTS—Methods using axial length had the lowest mean (+0.5 to +2.6%) and standard deviation (0.6 to 1.2%) of errors. Of methods using keratometry and ametropia only, the lowest mean (?1.4% to +4.4%) and standard deviation (2.9 to 4.3%) of errors was found for a new method described in this paper, and that used by the Heidelberg retina tomograph (HRT). The highest mean error (+2.2 to +7.1%) was found for Littmann's method. Littmann's correction was larger than the HRT's by 3.5 to 3.7%. The mean difference between the new and HRT methods and the "abbreviated axial length" method of Bennett is ?1.3 to +2.0%. The error of the "keratometry and ametropia" methods is related to axial length.?CONCLUSIONS—Methods using axial length are most accurate. The abbreviated axial length method of Bennett differs little from more detailed calculations and is appreciably more accurate than methods using keratometry and ametropia alone. If axial length is unknown, the new and the HRT methods give results closest to the abbreviated axial length method.?? Keywords: Littmann; magnification; optic disc; imaging PMID:9797665

Garway-Heath, D; Rudnicka, A; Lowe, T; Foster, P; Fitzke, F; Hitchings, R

1998-01-01

131

Scattered depressions with temporal preponderance in visual field test coexisting with optic disc temporal atrophy in cerebral arteriovenous malformation  

PubMed Central

In this article, the unusual association of optic disc temporal atrophy associated with scattered depressions with temporal preponderance in visual field test resembling incomplete bitemporal hemianopsia is reported. A 22-year-old man with cerebral arteriovenous malformation (AVM), which was located adjacent to the inferomedial portion of the posterior limb of the right internal capsule at the level of lateral ventricle, revealed interesting and unexpected ophthalmological findings. Possible mechanisms including anatomical variant, previously larger AVM, and retrograde optic neuropathy were mentioned. This case also highlighted that the usual complaint of visual disturbance might associate with unusual visual field defect in cerebral AVMs. PMID:24143070

Gokce, Gokcen; Oren, Nisa Cem; Ceylan, Osman Melih; Mumcuoglu, Tarkan; Hurmeric, Volkan

2013-01-01

132

Circumpapillary Course of Retinal Pigment Epithelium Can Be Fit to Sine Wave and Amplitude of Sine Wave Is Significantly Correlated with Ovality Ratio of Optic Disc  

PubMed Central

The purpose of this study was to develop a method of quantifying the degree of optic disc tilt in normal eyes. This was a prospective, observational cross sectional study of 126 right eyes of 126 healthy volunteers. The optic disc tilt was determined from the circular peripapillary optical coherence tomographic (OCT) scan images. The course of the retinal pigment epithelium (RPE) layer in the peripapillary cross sectional scan images was fit to a sine wave curve, and the amplitude of the sine curve was used to reflect the degree of the optic disc tilt in the optical axis. The repeatability of the amplitude determinations was calculated. The correlation between the amplitude and the ovality ratio of the optic disc was determined. The correlation between the amplitude and the body height was also calculated. The mean amplitudewas 36.6 ± 17.5 pixels, which was significantly and inversely correlated with the ovality ratio of the optic disc (R = -0.59, P<0.001). The intra-rater and inter-rater correlation coefficients of the amplitude were significant high (P<0.001, both). The amplitude was significantly and inversely correlated with the body height (R = -0.38, P<0.001), but not with the axial length. In conclusion, a sine wave function can be used to describe the course of the RPE in the circumpapillary OCT images. The results indicate that the amplitude of the sine wave can be used to represent the degree of optic disc tilt. Thus, the sine wave analyses can be used as a quantifiable and repeatable method to determine the optic disc tilt. PMID:25848777

Yoshihara, Naoya; Terasaki, Hiroto; Kii, Yuya; Tanaka, Minoru; Nakao, Kumiko

2015-01-01

133

Changes of number of cells expressing proliferation and progenitor cell markers with age in rabbit intervertebral discs.  

PubMed

Basic knowledge about the normal regeneration process within the intervertebral disc (IVD) is important to the understanding of the underlying biology. The presence of progenitor and stem cells in IVD has been verified. However, changes of number of progenitor and stem cells with age are still unknown. In this study, changes of cell proliferation and progenitor cell markers with age in IVD cells from rabbits of two different ages were investigated using flow cytometry, immunohistochemistry, real-time polymerase chain reaction, and western blot analysis. Proliferating cell nuclear antigen (PCNA) was chosen as a marker for proliferation, and Notch1, Jagged1, C-KIT, CD166 were chosen as stem/progenitor cell markers. Cell cycle analysis showed that cell number in the G2/M phase of the young rabbits was significantly higher than that of mature rabbits. Immunohistochemical staining demonstrated the expression of PCNA, C-KIT, CD166, Notch1, and Jagged1 in both young and mature annulus fibrosus (AF). Protein expressions of these cell markers in the young rabbits were all significantly higher than those in the mature rabbits. The expression levels of PCNA, CD166, C-KIT, Jagged1 were significantly higher in the AF, and PCNA, C-KIT in the nucleus pulposus from young rabbits than those from the mature rabbits. These findings demonstrated that both proliferation and progenitor cells exist in rabbit IVDs and the number of cells expressing proliferation and progenitor cell markers decreases with age in the rabbit IVD cells. Methods that are designed to maintain the endogenous progenitor cells and stimulate their proliferation could be successful in preventing or inhibiting degenerative disc disease. PMID:23449074

Yasen, Miersalijiang; Fei, Qinming; Hutton, William C; Zhang, Jian; Dong, Jian; Jiang, Xiaoxing; Zhang, Feng

2013-05-01

134

Impact of sintering temperature on the structural, electrical, and optical properties of doped ZnO nanoparticle-based discs  

NASA Astrophysics Data System (ADS)

In the current study, 20 nm zinc oxide (ZnO) nanoparticles were used to make high-density ZnO discs doped with Bi2O3 and Mn2O3 via the conventional ceramic processing method. Different sintering temperatures were found to have significant impacts on the ZnO discs, especially on enhancing grain growth even at a low sintering temperature of only 980 °C. The strong solid-state reaction during sintering may be attributed to the high surface area of the 20 nm ZnO nanoparticles that promoted a strong surface reaction even at low sintering temperatures. Moreover, the sintering process also improved the grain crystallinity, as shown in the lowering of the intrinsic compressive stress based on the X-ray diffraction lattice constant and full-wave half-maximum data. The sintering temperatures also significantly influenced the electrical properties of the doped ZnO discs with a marked drop in the breakdown voltage from 330 V (sample at 980 °C) to 80 V (sample at 1380 °C). The resistivity also experienced a dramatic drop from 304.4 k? cm (sample at 980 °C) to 98.86 k? cm (sample at 1380 °C). The observed shift in the energy band-gap from a higher to a lower value may be attributed to the conversion of compressive stress to tensile stress with increasing sintering temperature. The Raman spectra indicate that the sintering temperatures and dopants in the discs had significant effects on the E2(high) phonon mode and ZnO crystal structures. Therefore, the sintering process can be used as a new technique for controlling the breakdown voltage of doped ZnO discs made from ZnO nanoparticles with improved structural and optical properties.

Sendi, Rabab Khalid; Mahmud, Shahrom

2012-11-01

135

Minimal invasive localization of the germinal disc in ovo for subsequent chicken sexing using optical coherence tomography  

NASA Astrophysics Data System (ADS)

Reason for using optical coherence tomography (OCT) to locate the germinal disc is the questionable and ethically alarming killing of male layer chickens because for the layer line only the females are necessary. To avoid this and to protect the animal rights, the sex of the fertilized chicken egg has to be determined as early as possible in the unincubated state. Because the information whether the chick becomes male or female can be found in the germinal disc an accurate localization for sexing is essential. The germinal disc is located somewhere on top of the yolk and has a diameter of approximately 4 - 5 mm. Different imaging methods like ultrasonography, 3D-X-ray micro computed tomography and magnetic resonance imaging were used for localization until now, but found to be impractical. The goal of this study is to prove if OCT can be a moderate approach for the precise in ovo localization. Because the eggshell is an impenetrable barrier for OCT and to minimize the penetration of germs a very small hole is placed in the eggshell and a fan-shaped optical scanning pattern is used.

Burkhardt, Anke; Geissler, Stefan; Cimalla, Peter; Walther, Julia; Koch, Edmund

2010-02-01

136

Obtaining optic disc center and pixel region by automatic thresholding methods on morphologically processed fundus images.  

PubMed

Development of automatic retinal disease diagnosis systems based on retinal image computer analysis can provide remarkably quicker screening programs for early detection. Such systems are mainly focused on the detection of the earliest ophthalmic signs of illness and require previous identification of fundal landmark features such as optic disc (OD), fovea or blood vessels. A methodology for accurate center-position location and OD retinal region segmentation on digital fundus images is presented in this paper. The methodology performs a set of iterative opening-closing morphological operations on the original retinography intensity channel to produce a bright region-enhanced image. Taking blood vessel confluence at the OD into account, a 2-step automatic thresholding procedure is then applied to obtain a reduced region of interest, where the center and the OD pixel region are finally obtained by performing the circular Hough transform on a set of OD boundary candidates generated through the application of the Prewitt edge detector. The methodology was evaluated on 1200 and 1748 fundus images from the publicly available MESSIDOR and MESSIDOR-2 databases, acquired from diabetic patients and thus being clinical cases of interest within the framework of automated diagnosis of retinal diseases associated to diabetes mellitus. This methodology proved highly accurate in OD-center location: average Euclidean distance between the methodology-provided and actual OD-center position was 6.08, 9.22 and 9.72 pixels for retinas of 910, 1380 and 1455 pixels in size, respectively. On the other hand, OD segmentation evaluation was performed in terms of Jaccard and Dice coefficients, as well as the mean average distance between estimated and actual OD boundaries. Comparison with the results reported by other reviewed OD segmentation methodologies shows our proposal renders better overall performance. Its effectiveness and robustness make this proposed automated OD location and segmentation method a suitable tool to be integrated into a complete prescreening system for early diagnosis of retinal diseases. PMID:25433912

Marin, Diego; Gegundez-Arias, Manuel E; Suero, Angel; Bravo, Jose M

2015-02-01

137

Uveal melanomas near the optic disc or fovea. Visual results after proton beam irradiation  

SciTech Connect

Proximity to the disc and fovea is a risk factor for visual loss after proton beam irradiation of uveal melanomas. Of 562 eyes treated over a 10-year period with pretreatment visual acuity of 20/200 or better, 363 (64.6%) contained tumors within 2 disc diameters (DD) of the disc or fovea. Rates of visual loss after treatment to worse than 20/200 and causes of visual decline were evaluated using Kaplan-Meier analysis. Cumulative rates of visual loss among subjects with tumors near the disc or fovea were 33 and 47% 1 and 2 years after treatment compared to 17 and 28%, respectively, for subjects with tumors located farther from both structures. The leading cause of visual loss in the first year among eyes with tumors near the disc or fovea was retinal detachment. Controlling for other predictors of visual loss to worse than 20/200, location near the disc or fovea was independently related to visual loss primarily due to retinal detachment, cataract, and radiation retinopathy. Despite the unfavorable location of these tumors, over half of patients with 20/200 or better pretreatment visual acuity had useful vision 2 years after treatment.

Seddon, J.M.; Gragoudas, E.S.; Egan, K.M.; Glynn, R.J.; Munzenrider, J.E.; Austin-Seymour, M.; Goitein, M.; Verhey, L.; Urie, M.; Koehler, A.

1987-04-01

138

[Evaluation of stereometric parameters of optic disc and nerve fiber layer using HRT III. Report 1: reproducibility and intraobserver variability coefficients].  

PubMed

29 patients with initial primary open angle glaucoma were examined using Heidelberg retinal tomograph III (HRT III). In one visit 2 observers took 2 measurements. Intra- and interobserver errors (reproducibility and intraobserver variability coefficient) were calculated for 13 stereometric parameters of optic disc and retinal nerve fiber layer (RNFL). Rim area, cup depth (mean, maximum) and linear cup/disc ratios showed to be minimally variable. Cup area and volume, disc/cup area ratio were found to have greater variability. When performed by different observers (each entering his own contour) reproducibility was 1,4 fold lower compared with intraobserver reproducibility. PMID:21721272

Shpak, A A; Malakhanova, M K; Shormaz, I N

2011-01-01

139

Ultrahigh-Sensitivity Biomarker Sensing System Based on the Combination of Optical Disc Technologies and Nanobead Technologies  

NASA Astrophysics Data System (ADS)

The detection of biomarkers in body fluids is useful for the early detection of diseases or preventive medical care. Various types of equipment that detect biomarkers have been developed and used for various occasions. It is expected that further improvement of the detection sensitivity of biomarkers will enable the extension for their applications to various diseases. In this paper, we propose a new biomarker sensing system with higher sensitivity. In the system, by combining optical disc technologies and nanobead technologies, we developed a new sensing method. Target biomarkers are specifically immobilized onto the optical disc surface through an antigen-antibody reaction, then the nanobeads are immobilized on top of the biomarkers. Since the biomarkers and beads bind to each other one-on-one, the number of target biomarkers can be measured by counting the number of nanobeads using an optical pickup. The most significant advantage of this method is that measurement can be carried out in a fully digital scheme, in contrast to current sensing systems which measure light intensity in an analog scheme.

Tsujita, Koji; Hasegawa, Yuichi; Ono, Masayuki; Itonaga, Makoto; Sakamoto, Satoshi; Hatakeyama, Mamoru; Handa, Hiroshi

2013-09-01

140

Measurement of edge verticality of optical recording bits on blu-ray discs using scanning probe microscopy.  

PubMed

This work investigates recording bits on recordable and rewritable blu-ray discs using atomic force microscopy and conducting atomic force microscopy with high contrast, respectively. The geometric structure of the recording bits is clearly observed in images, which, when coupled with cross-section analysis, yields precise bit dimensions, and edge horizontal extended length values. The microscopic results are a valuable reference for increasing the recognition rate of digital signals in optical storage media. Furthermore, such a rapid and convenient measuring mode is an indispensable research tool for developing new recording materials and improving formation mechanisms. PMID:19484780

Chen, Sy-Hann; Lin, Wen-Siou; Wang, Wen-Ching

2010-01-01

141

Comparison of optical and electrical investigations of meat ageing  

NASA Astrophysics Data System (ADS)

Different ultrasonic, electromagnetic, electrical and optical methods are used for meat ageing detection. Muscles are turbid anisotropic media, they exhibit changes in electrical and optical properties according to the direction of the electrical and optical fields in the sample. The work assesses the feasibility of impedance measurements for meat ageing detection and their comparison with optical measurement of scattered light. The pork chop slices were used for their relative homogeneity. An investigation was carried out for the detection of the ageing of unpacked slices exposed directly to the air, and other packed in polyethylene bags. The electrical method is a promising method due to the possibility of getting much information and realizing cheap and fast enough measurement systems. The optical method allows measure the rotation of polarization plane in the range of 95 degrees within considered period. Nevertheless, further work has to be provided to determine closer relationships between optical scattering characteristics, electrical anisotropy in ageing-related tissue structural properties.

Prokopyeva, Elena; Tománek, Pavel; Kocová, Lucie; Palai-Dany, Tomáš; Balík, Zden?k.; Škarvada, Pavel; Grmela, Lubomír.

2013-05-01

142

A novel collinear optical system with annulus mirrors for holographic disc driver  

NASA Astrophysics Data System (ADS)

This paper focus on a novel collinear lens system with annulus mirrors for holographic disc driver, both information beam and reference beam are use same laser beam. The expanded and parallel laser beam, center part of it as the information beam then through Fourier transform lens, the beam around center part as a reference beam. On this axis, the ring reference beam reflected by two annulus shaped mirrors, then became a convergent beam, together with the information beam which through the first Fourier transform lens then produce holographic pattern to be write into the holographic disc behind of them, this lens system with two mirrors made the angle between information beam and reference beam more wide, can improved the multiplex level of holographic storage. Pair of Fourier transform lens with advance performance is designed in this paper.

Wang, Ye

2008-12-01

143

Run-to-run control of CMP process considering aging effects of pad and disc  

Microsoft Academic Search

CMP processes are known to be erratic and unstable. A simple control strategy is to predict the run-to-run process removal rate and then adjust the processing time based on the prediction. EWMA and PCC techniques are two most often used prediction techniques. In this work, we revise the PCC design to take into account the ages of the abrasive pad

Argon Chen; Ruey-Shan Guo; Y. L. Chou; C. L. Lin; Jowei Dun; S. A. Wu

1999-01-01

144

Heterozygous triplication of upstream regulatory sequences leads to dysregulation of matrix metalloproteinase 19 in patients with cavitary optic disc anomaly.  

PubMed

Patients with a congenital optic nerve disease, cavitary optic disc anomaly (CODA), are born with profound excavation of the optic nerve resembling glaucoma. We previously mapped the gene that causes autosomal-dominant CODA in a large pedigree to a chromosome 12q locus. Using comparative genomic hybridization and quantitative PCR analysis of this pedigree, we report identifying a 6-Kbp heterozygous triplication upstream of the matrix metalloproteinase 19 (MMP19) gene, present in all 17 affected family members and no normal members. Moreover, the triplication was not detected in 78 control subjects or in the Database of Genomic Variants. We further detected the same 6-Kbp triplication in one of 24 unrelated CODA patients and in none of 172 glaucoma patients. Analysis with a Luciferase assay showed that the 6-Kbp sequence has transcription enhancer activity. A 773-bp fragment of the 6-Kbp DNA segment increased downstream gene expression eightfold, suggesting that triplication of this sequence may lead to dysregulation of the downstream gene, MMP19, in CODA patients. Lastly, immunohistochemical analysis of human donor eyes revealed strong expression of MMP19 in optic nerve head. These data strongly suggest that triplication of an enhancer may lead to overexpression of MMP19 in the optic nerve that causes CODA. PMID:25581579

Hazlewood, Ralph J; Roos, Benjamin R; Solivan-Timpe, Frances; Honkanen, Robert A; Jampol, Lee M; Gieser, Stephen C; Meyer, Kacie J; Mullins, Robert F; Kuehn, Markus H; Scheetz, Todd E; Kwon, Young H; Alward, Wallace L M; Stone, Edwin M; Fingert, John H

2015-03-01

145

Blu-ray disc  

Microsoft Academic Search

A key aspect of any novel optical disc format is compatibility with existing, widely used formats. For BD this means that the optical disc drive must be able to read and write BDs as well as DVDs and CDs, i.e. the dual CD\\/DVD compatibility of present day drives must be enlarged to triple CD\\/DVD\\/BD-compatibility. The main obstacle originates from the

S. Stallinga

2005-01-01

146

Lumbar Disc Herniation in Adolescence  

Microsoft Academic Search

Lumbar disc herniation very rarely occurs in adolescence. The aim of this study was to assess the radiological, clinical and surgical features and case outcomes for adolescents with lumbar disc herniation, and to compare with adult cases. The cases of 17 adolescents (7 girls and 10 boys, age range 13–17 years) who were surgically treated for lumbar disc herniation in

Serdar Ozgen; Deniz Konya; O. Zafer Toktas; Adnan Dagcinar; M. Memet Ozek

2007-01-01

147

Optical Coherence Tomography Study of Retinal Changes in Normal Aging and after Ischemia.  

PubMed

Purpose. Age-related thinning of the retinal ganglion cell axons in the nerve fiber layer has been measured in humans using optical coherence tomography (OCT). In this study, we used OCT to measure inner retinal changes in 3-months-, one-year, and two-year-old mice and after experimental anterior ischemic optic neuropathy (AION). Methods. We used OCT to quantify retinal thickness in over 200 eyes at different ages before and after photochemical thrombosis model of AION. The scans were manually or automatically segmented. Results. In normal aging, there was 1.3 µm thinning of the ganglion cell complex (GCC) between 3-months and 1-year (P < 0.0001) and no further thinning at 2-years. In studying age-related inner retinal changes, measurement of the GCC (circular scan) was superior to the total retinal thickness (posterior pole scan) despite the need for manual segmentation because it was not contaminated by outer retinal changes. Three-weeks after AION, there was 8.9 µm thinning of the GCC (circular scan; P < 0.0001) and 50 µm thinning of the optic disc (posterior pole scan; P < 0.0001), and 17 µm thinning of the retinae (posterior pole scan; P < 0.0001) in the 3 months-old group. Changes in the older eyes were similar to that of the 3-month-old group. Conclusions. OCT imaging of a large number eyes showed that, like humans, mice exhibited small, age-related inner retinal thinning. GCC was superior to quantify age-related changes after AION, and both circular and posterior pole scans were useful to track short-term changes after AION. PMID:25414186

Shariati, Mohammad Ali; Ho, Joyce K; Liao, Yaping Joyce

2014-11-20

148

Design, Installation and Post-Implementation Assessment of an Optical Disc Based Storage and Retrieval System for Images of Engineering Contract Documents.  

ERIC Educational Resources Information Center

Describes an image storage system for contract documentation in the Engineering Directorate of Thames Water Utilities (England) which uses optical disc storage and a relational database for indexing and retrieval of nearly 500,000 pages in compressed image format, and provides end user access through 7 workstations. Requirements, feasibility…

Ashford, J. H.; Masters, A. M.

1992-01-01

149

Diagnosis of diabetic retinopathy: automatic extraction of optic disc and exudates from retinal images using marker-controlled watershed transformation.  

PubMed

Due to increasing number of diabetic retinopathy cases, ophthalmologists are experiencing serious problem to automatically extract the features from the retinal images. Optic disc (OD), exudates, and cotton wool spots are the main features of fundus images which are used for diagnosing eye diseases, such as diabetic retinopathy and glaucoma. In this paper, a new algorithm for the extraction of these bright objects from fundus images based on marker-controlled watershed segmentation is presented. The proposed algorithm makes use of average filtering and contrast adjustment as preprocessing steps. The concept of the markers is used to modify the gradient before the watershed transformation is applied. The performance of the proposed algorithm is evaluated using the test images of STARE and DRIVE databases. It is shown that the proposed method can yield an average sensitivity value of about 95%, which is comparable to those obtained by the known methods. PMID:20703768

Reza, Ahmed Wasif; Eswaran, C; Dimyati, Kaharudin

2011-12-01

150

Optics in the Age of Euler  

NASA Astrophysics Data System (ADS)

This book studies the eighteenth-century origins and early phase of a fundamental debate in optics: whether light is a particle or wave. Specifically, it is the first in-depth study of the contents and reception of Leonhard Euler's wave theory of light. The author shows that contrary to what has been assumed, the debate did not start in 1672 with Newton's particle theory of light. Rather, it only really got under way after Euler published his wave theory in 1746. He also corrects the misapprehension that Newton's theory was prevalently held in Germany in the early years of the debate, but really only became dominant around 1795. In his discussion, Professor Hakfoort demonstrates in dramatic fashion the relevance of chemical experiments on physical optics. Finally, in the epilogue, the author reflects on the mathematical, experimental, and metaphysical aspects of physical optics that shaped early modern science.

Hakfoort, Casper

1995-01-01

151

Lens Design of Compatible Objective Lens for Blu-ray Disc and Digital Versatile Disk with Diffractive Optical Element and Phase Steps  

Microsoft Academic Search

A two-element objective lens which is compatible with for digital versatile disk (DVD) and Blu-ray Disc (BD) and has adequate optical performances in terms of off-axis wavefront and on-axis chromatic aberration for both optical heads has been designed. The first-order diffracted light is used for DVD and the second-order one is used for BD. We analyzed chromatic spherical aberration and

Yasuhiro Tanaka; Yoshiaki Komma; Yoshiyuki Shimizu; Tomoaki Shimazaki; Jun Murata; Sadao Mizuno

2004-01-01

152

Optical fiber corrosion sensors for aging aircraft  

NASA Astrophysics Data System (ADS)

Optical fiber corrosion sensors are being developed to address the high service costs associated with current structural maintenance procedures for civilian and military assets. A distributed optical fiber sensor system will help reduce the costs associated with corrosion damage and extend the lifetime of existing assets. Annual national losses in time, labor, materials and systems has been estimated in the billions of dollars. Additional costs arise from system downtime that results from disassembly procedures necessary to locate corrosion damage in remote locations. Furthermore, the potential to damage other system parts during maintenance is increased when disassembly and reassembly occurs. The development of on-line optical fiber sensors capable of detecting corrosion would eliminate a significant portion of the maintenance costs. We present recent test results using optical fiber long-period grating (LPG) corrosion sensors. With the appropriate coating, the sensors can be designed to detect water or metal ions in otherwise inaccessible regions of the aircraft. The LPG sensors can be designed with low temperature cross-sensitivity, multiplexed along a single fiber, and can be demodulated using a simple, low-cost spectrum analyzer.

Greene, Jonathan A.; Jones, Mark E.; Bailey, Timothy A.; Perez, Ignacio M.

1998-03-01

153

Optical properties of GaN-based nanowires containing a single Al(0.14)Ga(0.86)N/GaN quantum disc.  

PubMed

The optical properties of wurtzite GaN nanowires containing single Al0.14Ga0.86N/GaN quantum discs of different thickness have been investigated. The dependence of the photoluminescence (PL) transition energy on the quantum disc thickness and the thickness of a lateral AlGaN shell has been simulated in the framework of a three-dimensional effective mass model, accounting for the presence of a lateral AlGaN shell, strain state and the piezoelectric and spontaneous polarization. The predicted transition energies are in good agreement with the statistics realized on more than 40 single nanowire emission spectra and PL spectra of ensembles of nanowires. The emission spectra of the single quantum discs exhibit a Lorentzian shape with a homogeneous line width as low as 3 meV. Finally, we discuss the dependence of the interband transition energy on diameter. PMID:23459100

Jacopin, G; Rigutti, L; Teubert, J; Julien, F H; Furtmayr, F; Komninou, Ph; Kehagias, Th; Eickhoff, M; Tchernycheva, M

2013-03-29

154

Macular Pigment Optical Density in an Ageing Irish Population: The Irish Longitudinal Study on Ageing  

Microsoft Academic Search

Purpose: The 3 carotenoids lutein, zeaxanthin, and meso-zeaxanthin, which account for the ‘yellow spot’ at the macula and which are referred to as macular pigment (MP), are believed to play a role in visual function and protect against age-related macular degeneration (AMD) via their optical and antioxidant properties. This study was undertaken to compare MP optical density (MPOD) in a

John M. Nolan; Roseanne Kenny; Claire O’Regan; Hilary Cronin; James Loughman; Eithne E. Connolly; Patricia Kearney; Edward Loane; Stephen Beatty

2010-01-01

155

Free space optical communications: coming of age  

NASA Astrophysics Data System (ADS)

Information superiority, where for the military or business, is the decisive advantage of the 21st Century. While business enjoys the information advantage of robust, high-bandwidth fiber optic connectivity that heavily leverages installed commercial infrastructure and service providers, mobile military forces need the wireless equivalent to leverage that advantage. In other words, an ability to deploy anywhere on the globe and maintain a robust, reliable communications and connectivity infrastructure, equivalent to that enjoyed by a CONUS commercial user, will provide US forces with information superiority. Assured high-data-rate connectivity to the tactical user is the biggest gap in developing and truly exploiting the potential of the information superiority weapon. Though information superiority is much discussed and its potential is well understood, a robust communications network available to the lowest military echelons is not yet an integral part of the force structure, although high data rate RF communications relays, e.g., Tactical Common Data Link, and low data SATCOM, e.g, Ku Spread Spectrum, are deployed and used by the military. This may change with recent advances in laser communications technologies created by the fiber optic communications revolution. This paper will provide a high level overview of the various laser communications programs conducted over the last 30 plus years, and proposed efforts to get these systems finally deployed.

Stotts, Larry B.; Stadler, Brian; Lee, Gary

2008-04-01

156

A characteristic optic disc appearance associated with myopia in subjects with Graves’ ophthalmopathy and in subjects with primary open-angle glaucoma  

PubMed Central

Purpose To determine if qualitatively defining the appearance of optic disc change was a valid characteristic of myopia in subjects with Graves’ ophthalmopathy (GO) or primary open-angle glaucoma (POAG). Methods We defined typical tilt appearance as the simultaneous presence of the following: an elliptical optic disc, a crescent, unequal sharpness of the cupping margin (horizontally), and nasally displaced vessels in the optic cup. Ninety-two eyes from 92 subjects each with GO or with POAG and no severe complications were included in the study after matching for spherical refractive errors. Using our definition of tilt appearance, two independent observers subjectively judged optic disc photographs. One observer repeated judgments in 70 randomly selected eyes and judgment reproducibility was assessed using kappa statistics. Tilt ratio was used as a quantitative parameter. Results The numbers of eyes judged as having a typical tilt appearance in the GO group and in the POAG group were 25 (27.2%) and 39 (42.4%), respectively, by one observer (P = 0.0297), and 12 (13%) and 44 (47.8%), respectively, by another observer (P < 0.0001). Intra- and interobserver reproducibility of tilt judgment were very good (kappa = 0.93) and good (kappa = 0.65), respectively. Tilt ratio did not significantly differ between the two groups. Analytical results including background factors were essentially the same for the two observers: multivariate logistic regression for one observer’s judgment showed that the presence of the typical tilt appearance was associated with belonging to the glaucoma group (odds ratio [OR], 6.25; P = 0.0054), tilt ratio (OR per 0.01, 0.77; P < 0.0001), and spherical refractive error (OR per diopter, 0.80; P < 0.003). Conclusion The optic disc feature we designated as typical tilt was associated with myopia, and its frequency was higher in subjects with POAG compared to those with GO. PMID:23326183

Yamazaki, Sei; Inoue, Rishu; Tsuboi, Toshikazu; Kozaki, Ai; Inoue, Toshu; Inoue, Toyoko; Inoue, Yoichi

2013-01-01

157

The Coming of Age of Adaptive Optics  

NASA Astrophysics Data System (ADS)

How Ground-Based Astronomers Beat the Atmosphere Adaptive Optics (AO) is the new ``wonder-weapon'' in ground-based astronomy. By means of advanced electro-optical devices at their telescopes, astronomers are now able to ``neutralize'' the image-smearing turbulence of the terrestrial atmosphere (seen by the unaided eye as the twinkling of stars) so that much sharper images can be obtained than before. In practice, this is done with computer-controlled, flexible mirrors which refocus the blurred images up to 100 times per second, i.e. at a rate that is faster than the changes in the atmospheric turbulence. This means that finer details in astronomical objects can be studied and also - because of the improved concentration of light in the telescope's focal plane - that fainter objects can be observed. At the moment, Adaptive Optics work best in the infrared part of spectrum, but at some later time it may also significantly improve observations at the shorter wavelengths of visible light. The many-sided aspects of this new technology and its impact on astronomical instrumentation was the subject of a recent AO conference [1] with over 150 participants from about 30 countries, presenting a total of more than 100 papers. The Introduction of AO Techniques into Astronomy The scope of this meeting was the design, fabrication and testing of AO systems, characterisation of the sources of atmospheric disturbance, modelling of compensation systems, individual components, astronomical AO results, non-astronomical applications, laser guide star systems, non-linear optical phase conjugation, performance evaluation, and other areas of this wide and complex field, in which front-line science and high technology come together in a new and powerful symbiosis. One of the specific goals of the meeting was to develop contacts between AO scientists and engineers in the western world and their colleagues in Russia and Asia. For the first time at a conference of this type, nine Russian scientists were invited to give presentations; this was made possible by a grant from the European Office of Aerospace Research and Development (EOARD) Following the declassification of much AO technology and the introduction of AO into regular astronomical research several years ago, first at ESO with the ``Come-On'' system at La Silla [2], the fundamental importance of AO to ground-based astronomy has now become widely recognised. Since the last AO meeting that was held in Garching in August 1993, many groups in different countries have been developing such systems and have begun to use them. As Fritz Merkle (Carl Zeiss, Jena) emphasized during a review talk, there has also been an interesting opening of new commercial and industrial AO applications, such as for high power lasers and for laser communications systems. However, the chief field of AO development and application remains astronomy and the vast majority of papers presented at the conference were concerned, directly or indirectly, with this science. Towards Scientific and Technological Maturity According to Martin Cullum (ESO), the organiser of this conference, it is apparent that a certain technological maturity has been reached during the past two years. However, it is also much more widely realised that it is not straightforward to produce good science, even with a high-performance AO system. A detailed characterization of the atmosphere, painstaking system calibrations and a lot of hard work during the astronomical observations and especially at the time of the reduction and interpretation of the voluminous datasets are necessary to obtain reliable results of high quality. Many of the presentations reflected this fact. From the technical standpoint, highlights of the meeting included the significant progress that was reported in the development of adaptive secondary mirrors for the upgrade of the Multi-Mirror-Telescope (MMT) in Arizona, the initial tests of the laser guide-star AO system installed on the Lick 3-metre telescope in California, as well as the development of an advanced visible-light AO

1995-10-01

158

Accelerated optical polymer aging studies for LED luminaire applications  

NASA Astrophysics Data System (ADS)

There is a need in the lighting industry to design and implement accelerated aging methods that accurately simulate the aging process of LED luminaire components. In response to this need, we have built a flexible and reliable system to study the aging characteristics of optical polymer materials, and we have employed it to study a commercially available LED luminaire diffuser made of PMMA. The experimental system consists of a "Blue LED Emitter" and a working surface. Both the temperatures of the samples and the optical powers of the LEDs are appropriately characterized in the system. Several accelerated aging experiments are carried out at different temperatures and optical powers over a 90 hour period and the measured transmission values are used as inputs to a degradation model derived using plausibility arguments. This model seems capable of predicting the behavior of the material as a function of time, temperature and optical power. The model satisfactorily predicts the measured transmission values of diffusers aged in luminaires at two different times and thus can be used to make application recommendations for this material. Specifically, at 35000 hours (the manufacturer's stated life of the luminaire) and at the typical operational temperature of the diffuser, the model predicts a transmission loss of only a few percent over the original transmission of the material at 450 nm, which renders this material suitable for this application.

Estupiñán, Edgar; Wendling, Peter; Kostrun, Marijan; Garner, Richard

2013-09-01

159

Inter- and intraobserver variation in the analysis of optic disc images: comparison of the Heidelberg retina tomograph and computer assisted planimetry  

PubMed Central

AIMS—The development of imaging and measurement techniques has brought the prospect of greater objectivity in the measurement of optic disc features, and therefore better agreement between observers. The purpose of this study was to quantify and compare the variation between observers using two measurement devices.?METHODS—Optic disc photographs and images from the Heidelberg retina tomograph (HRT) of 30 eyes of 30 subjects were presented to six observers for analysis, and to one observer on five separate occasions. Agreement between observers was studied by comparing the analysis of each observer with the median result of the other five, and expressed as the mean difference and standard deviation of differences between the observer and the median. Inter- and intraobserver variation was calculated as a coefficient of variation (mean SD/mean × 100).?RESULTS—For planimetry, agreement between observers was dependent on observer experience, for the HRT it was independent. Agreement between observers (SD of differences as a percentage of the median) for optic disc area was 4.0% to 7.2% (planimetry) and 3.3% to 6.0% (HRT), for neuroretinal rim area it was 10.8% to 21.0% (planimetry) and 5.2% to 9.6% (HRT). The mean interobserver coefficient of variation for optic disc area was 8.1% (planimetry) and 4.4% (HRT), for neuroretinal rim area it was 16.3% (planimetry) and 8.1% (HRT), and (HRT only) for rim volume was 16.3%, and reference height 9.1%. HRT variability was greater for the software version 1.11 reference plane than for version 1.10. The intraobserver coefficient of variation for optic disc area was 1.5% (planimetry) and 2.4% (HRT), for neuroretinal rim area it was 4.0% (planimetry) and 4.5% (HRT).?CONCLUSIONS—Variation between observers is greatly reduced by the HRT when compared with planimetry. However, levels of variation, which may be clinically significant, remain for variables that depend on the subjective drawing of the disc margin.?? PMID:10340972

Garway-Heath, D; Poinoosawmy, D; Wollstein, G; Viswanathan, A; Kamal, D; Fontana, L; Hitchings, R

1999-01-01

160

AUTOMATIC EXTRACTION OF THE OPTIC DISC BOUNDARY FOR DETECTING RETINAL DISEASES  

E-print Network

Boundary extraction, fundus image, Automatic Feature Detection, Glaucoma, Active Shape Model 1 Introduction or geometrical, can be used to determine the occurrence of retinal diseases such as Glaucoma. Glaucoma is one.7% of the cases being affected by it [19]. Glaucoma leads to irreversible structural changes in the Optic Nerve

Li, Baihua

161

Disc-loss episode in the Be shell optical counterpart to the high-mass X-ray binary IGR J21343+4738  

NASA Astrophysics Data System (ADS)

Context. Present X-ray missions are regularly discovering new X-ray and ?-ray sources. The identification of their counterparts at other wavelengths allows us to determine their nature. Aims: The main goal of this work is to determine the properties of the optical counterpart to the INTEGRAL source IGR J21343+4738, and to study its long-term optical variability. Although its nature as a Be/X-ray binary has been suggested, little is known about its physical parameters. Methods: We have been monitoring IGR J21343+4738 since 2009 in the optical band. We present BVRI optical photometric and spectroscopic observations covering the wavelength band 4000-7500 Å. The photometric data allowed us to derive the colour excess E(B - V) and estimate the distance. The blue-end spectra were used to determine the spectral type of the optical companion, while the spectra around the H? line allowed us to study the long-term structural changes in the circumstellar disc. Results: We find that the optical counterpart to IGR J21343+4738 is a V = 14.1 B1IVe shell star located at a distance of ~8.5 kpc. The H? line changed from an absorption-dominated profile to an emission-dominated profile, and then back again into absorption. In addition, fast line profile asymmetries were observed once the disc developed. Although the Balmer lines are the most strongly affected by shell absorption, we find that shell characteristics are also observed in He I lines. Conclusions: The optical spectral variability of IGR J21343+4738 is attributed to the formation of an equatorial disc around the Be star and the development of an enhanced density perturbation that revolves inside the disc. We have witnessed the formation and dissipation of the circumstellar disc. The strong shell profile of the H? and He I lines and the fact that no transition from the shell phase to a pure emission phase is observed imply that we are seeing the system near edge-on. The reduced spectra are available as FITS files at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A137

Reig, P.; Zezas, A.

2014-01-01

162

Bilateral ischemic optic neuropathy after transurethral prostatic resection: a case report  

Microsoft Academic Search

BACKGROUND: Nonarteritic ischemic optic neuropathy affects the anterior portion of the optic nerve and is characterized by sudden, painless visual loss. The affected eye has a relative afferent pupillary defect. The typical funduscopic appearance includes optic disc edema, with associated nerve fiber layer hemorrhage. Risk factors include advanced age, systemic hypertension, nocturnal hypotension, diabetes mellitus, and a small cup-to-disc ratio.

Luis M Sadaba; Alfredo Garcia-Layana; Miguel J Maldonado; Jose M Berian

2006-01-01

163

Multilayer Optical Read-Only-Memory Disk Applicable to Blu-ray Disc Standard Using a Photopolymer Sheet with a Recording Capacity of 100 GB  

Microsoft Academic Search

We have been investigating a multilayer optical disk applicable to Blu-ray Disc (BD) standard using a photopolymer (2P) sheet in order to realize a recording capacity of 100 GB on a 12-cm-diameter disk. We had already developed a 2P sheet utilizing the multilayer disk. In this study, we developed a BD-type quad-layer disk using the 2P sheet, and investigated readout

Noriyoshi Shida; Takanobu Higuchi; Yasuo Hosoda; Hiroko Miyoshi; Akio Nakano; Katsunori Tsuchiya

2004-01-01

164

A comparative study of argon laser and krypton laser in the treatment of diabetic optic disc neovascularisation  

Microsoft Academic Search

A comparative study of the relative efficacy of the krypton and argon lasers in the treatment of disc new vessels in diabetic retinopathy was made. Resolution of the disc new vessels was achieved in both instances. There were clinical differences in the use and effects of the 2 lasers.

W E Schulenburg; A M Hamilton; R K Blach

1979-01-01

165

A survey of 286 Virgo cluster galaxies at optical griz and near-IR H band: surface brightness profiles and bulge-disc decompositions  

NASA Astrophysics Data System (ADS)

We present and g-, r-, i-, z- and H-band surface brightness profiles and bulge-disc decompositions for a morphologically broad sample of 286 Virgo Cluster Catalogue (VCC) galaxies. The H-band data come from a variety of sources including our survey of 171 VCC galaxies at the University of Hawaii (UH) 2.2-m telescope, Canada-France-Hawaii Telescope (CFHT) and United Kingdom Infrared Telescope (UKIRT), and another 115 galaxies from the Two Micron All Sky Survey (2MASS) and GOLDMine archives. The optical data for all 286 VCC galaxies were extracted from the Sloan Digital Sky Survey (SDSS) images. The H-band and the SDSS griz data were analysed in a homogeneous manner using our own software, yielding a consistent set of deep, multiband surface brightness profiles for each galaxy. Average surface brightness profiles per morphological bin were created in order to characterize the variety of galaxy light profiles across the Hubble sequence. The 1D bulge-disc decomposition parameters, as well as non-parametric galaxy measures, such as effective radius, effective surface brightness and light concentration, are presented for all 286 VCC galaxies in each of the five optical/near-infrared wavebands. The profile decompositions account for bulge and disc components, spiral arms, nucleus and atmospheric blurring. The Virgo spiral galaxy bulges typically have a Sérsic index n˜ 1, while elliptical galaxies prefer n˜ 2. No galaxy spheroid requires n > 3. The light profiles for 70 per cent of the Virgo elliptical galaxies reveal the presence of both a spheroid and disc component. A more in-depth discussion of the structural parameter trends can be found in McDonald, Courteau & Tully. The data provided here should serve as a base for studies of galaxy structure and stellar populations in the cluster environment. The galaxy light profiles and bulge-disc decomposition results are available at the Centre de Données astronomiques de Strasbourg (CDS; ) and the author's own website ().

McDonald, Michael; Courteau, Stéphane; Tully, R. Brent; Roediger, Joel

2011-07-01

166

Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing  

NASA Astrophysics Data System (ADS)

In most industrial states a huge amount of newly hatched male layer chickens are usually killed immediately after hatching by maceration or gassing. The reason for killing most of the male chickens of egg producing races is their slow growth rate compared to races specialized on meat production. When the egg has been laid, the egg contains already a small disc of cells on the surface of the yolk known as the blastoderm. This region is about 4 - 5 mm in diameter and contains the information whether the chick becomes male or female and hence allows sexing of the chicks by spectroscopy and other methods in the unincubated state. Different imaging methods like sonography, 3D-X-ray micro computed tomography and magnetic resonance imaging were used for localization of the blastoderm until now, but found to be impractical for different reasons. Optical coherence tomography (OCT) enables micrometer-scale, subsurface imaging of biological tissue and could therefore be a suitable technique for an accurate localization. The intention of this study is to prove if OCT can be an appropriate approach for the precise in ovo localization.

Burkhardt, Anke; Geissler, Stefan; Koch, Edmund

2010-04-01

167

Indium Phosphide Planar Integrated Optics Comes of Age Jens Noeckel  

E-print Network

Indium Phosphide Planar Integrated Optics Comes of Age Jens Noeckel Tom Pierson Jane Zucker exceeds supply. Indium Phosphide: Adapting Form to Function PLCs can serve many roles in fiberoptic of the spectrum, the current material of choice is indium phosphide. When compared with the sophistication

Nöckelm, Jens

168

Accretion discs  

NASA Astrophysics Data System (ADS)

Accretion discs are flattened astronomical objects made of rapidly rotating gas which slowly spirals onto a central gravitating body. The gravitational energy of infalling matter extracted in accretion discs powers stellar binaries, active galactic nuclei, proto-planetary discs and some gamma-ray bursts. The black hole accretion in quasars is the most powerful and efficient stationary engine known in the universe. In accretion discs the high angular momentum of rotating matter is gradually transported outwards by stresses (related to turbulence, viscosity, shear and magnetic fields). This gradual loss of angular momentum allows matter to progressively move inwards, towards the centre of gravity. The gravitational energy of the gaseous matter is thereby converted to heat. A fraction of the heat is converted into radiation, which partially escapes and cools down the accretion disc. Accretion disc physics is thus governed by a non-linear combination of many processes, includ! ing gravity, hydrodynamics, viscosity, radiation and magnetic fields.

Abramowicz, Marek A.; Straub, Odele

2014-08-01

169

Compatible Objective Lens for Blu-ray Disc and Degital Versatile Disc Using Diffractive Optical Element and Phase-Step Element which Corrects both Chromatic and Spherical Aberrations  

Microsoft Academic Search

A compatible lens with a diffractive optical element that overcomes differences in disk thickness and longitudinal chromatic aberration and phase steps that eliminate chromatic spherical aberrations are proposed. Both blue and red parallel incident rays can be converged on both disks; therefore, the servo and readout signals can be detected by a single common photodetector. A compatible optical head, which

Yoshiaki Komma; Yasuhiro Tanaka; Sadao Mizuno

2004-01-01

170

A trifurcated fiber-optic-probe-based optical system designed for AGEs measurement  

NASA Astrophysics Data System (ADS)

Advanced Glycation End-products (AGEs) are biochemical end-products of non-enzymatic glycation and are formed irreversibly in human serum and skin tissue. AGEs are thought to play an important role in the pathogenesis of diabetes and corresponding complications. All conventional methods for measuring AGEs must take sampling and measure in vitro. These methods are invasive and have the problem of relatively time-consuming. AGEs have fluorescent characteristics. Skin AGEs can be assessed noninvasively by collecting the fluorescence emitted from skin tissue when excited with proper light. However, skin tissue has absorption and scattering effects on fluorescence of AGEs, it is not reliable to evaluate the accumulation of AGEs according the emitted fluorescence but not considering optical properties of skin tissue. In this study, a portable system for detecting AGEs fluorescence and skin reflectance spectrum simultaneously has been developed. The system mainly consists of an ultraviolet light source, a broadband light source, a trifurcated fiber-optic probe, and a compact charge coupled device (CCD) spectrometer. The fiber-optic probe consists of 36 optical fibers which are connected to the ultraviolet light source, 6 optical fibers connected to the broadband light source, and a core fiber connected to the CCD spectrometer. Demonstrative test measurements with the system on skin tissue of 40 healthy subjects have been performed. Using parameters that are calculated from skin reflectance spectrum, the distortion effects caused by skin absorption and scattering can be eliminated, and the integral intensity of corrected fluorescence has a strong correlation with the accumulation of AGEs. The system looks very promising for both laboratory and clinical applications to monitor AGEs related diseases, especially for chronic diabetes and complications.

Wang, Yikun; Zhang, Long; Zhu, Ling; Liu, Yong; Zhang, Gong; Wang, An

2012-03-01

171

A trifurcated fiber-optic-probe-based optical system designed for AGEs measurement  

NASA Astrophysics Data System (ADS)

Advanced Glycation End-products (AGEs) are biochemical end-products of non-enzymatic glycation and are formed irreversibly in human serum and skin tissue. AGEs are thought to play an important role in the pathogenesis of diabetes and corresponding complications. All conventional methods for measuring AGEs must take sampling and measure in vitro. These methods are invasive and have the problem of relatively time-consuming. AGEs have fluorescent characteristics. Skin AGEs can be assessed noninvasively by collecting the fluorescence emitted from skin tissue when excited with proper light. However, skin tissue has absorption and scattering effects on fluorescence of AGEs, it is not reliable to evaluate the accumulation of AGEs according the emitted fluorescence but not considering optical properties of skin tissue. In this study, a portable system for detecting AGEs fluorescence and skin reflectance spectrum simultaneously has been developed. The system mainly consists of an ultraviolet light source, a broadband light source, a trifurcated fiber-optic probe, and a compact charge coupled device (CCD) spectrometer. The fiber-optic probe consists of 36 optical fibers which are connected to the ultraviolet light source, 6 optical fibers connected to the broadband light source, and a core fiber connected to the CCD spectrometer. Demonstrative test measurements with the system on skin tissue of 40 healthy subjects have been performed. Using parameters that are calculated from skin reflectance spectrum, the distortion effects caused by skin absorption and scattering can be eliminated, and the integral intensity of corrected fluorescence has a strong correlation with the accumulation of AGEs. The system looks very promising for both laboratory and clinical applications to monitor AGEs related diseases, especially for chronic diabetes and complications.

Wang, Yikun; Zhang, Long; Zhu, Ling; Liu, Yong; Zhang, Gong; Wang, An

2011-11-01

172

Degeneration of the intervertebral disc  

Microsoft Academic Search

The intervertebral disc is a cartilaginous structure that resembles articular cartilage in its biochemistry, but morphologically it is clearly different. It shows degenerative and ageing changes earlier than does any other connective tissue in the body. It is believed to be important clinically because there is an association of disc degeneration with back pain. Current treatments are predominantly conservative or,

Jill PG Urban; Sally Roberts

2003-01-01

173

Degenerative disc and vertebral disease – basic sciences  

Microsoft Academic Search

This article summarizes the pathophysiology of spinal degeneration from a mechanistic basic sciences viewpoint, emphasizing the interdependence of discs and vertebrae. Intervertebral disc degeneration differs from normal ageing by involving physical disruption, typically in the form of annular fissures, prolapse or endplate fracture. Frustrated attempts to heal this large avascular tissue give rise to the typical biological features of disc

Michael A. Adams

2009-01-01

174

Combined Anti-Inflammatory and Anti-AGE Drug Treatments Have a Protective Effect on Intervertebral Discs in Mice with Diabetes  

PubMed Central

Objective Diabetes and low back pain are debilitating diseases and modern epidemics. Diabetes and obesity are also highly correlated with intervertebral disc (IVD) degeneration and back pain. Advanced-glycation-end-products (AGEs) increase reactive-oxygen-species (ROS) and inflammation, and are one cause for early development of diabetes mellitus. We hypothesize that diabetes results in accumulation of AGEs in spines and associated spinal pathology via increased catabolism. We present a mouse model showing that: 1) diabetes induces pathological changes to structure and composition of IVDs and vertebrae; 2) diabetes is associated with accumulation of AGEs, TNF?, and increased catabolism spinal structures; and 3) oral-treatments with a combination of anti-inflammatory and anti-AGE drugs mitigate these diabetes-induced degenerative changes to the spine. Methods Three age-matched groups of ROP-Os mice were compared: non-diabetic, diabetic (streptozotocin (STZ)-induced), or diabetic mice treated with pentosan-polysulfate (anti-inflammatory) and pyridoxamine (AGE-inhibitor). Mice were euthanized and vertebra-IVD segments were analyzed by ?CT, histology and Immunohistochemistry. Results Diabetic mice exhibited several pathological changes including loss in IVD height, decreased vertebral bone mass, decreased glycosaminoglycan content and morphologically altered IVDs with focal deposition of tissues highly expressing TNF?, MMP-13 and ADAMTS-5. Accumulation of larger amounts of methylglyoxal suggested that AGE accumulation was associated with these diabetic degenerative changes. However, treatment prevented or reduced these pathological effects on vertebrae and IVD. Conclusion This is the first study to demonstrate specific degenerative changes to nucleus pulposus (NP) morphology and their association with AGE accumulation in a diabetic mouse model. Furthermore, this is the first study to demonstrate that oral-treatments can inhibit AGE-induced ROS and inflammation in spinal structures and provide a potential treatment to slow progression of degenerative spine changes in diabetes. Since diabetes, IVD degeneration, and accumulation of AGEs are frequent consequences of aging, early treatments to reduce AGE-induced ROS and Inflammation may have broad public-health implications. PMID:23691192

Illien-Junger, Svenja; Grosjean, Fabrizio; Laudier, Damien M.; Vlassara, Helen; Striker, Gary E.; Iatridis, James C.

2013-01-01

175

Aging-caused changes in optical anisotropy of fibrous tissues  

NASA Astrophysics Data System (ADS)

Energy density approach as a modification of the coherent potential approximation was applied to analyze the influence of aging-caused changes in the fibrous tissue on its birefringence. The real fibrous tissue such as tendon was modeled by disordered array of partially oriented dielectric cylinders illuminated by a normally incident linearly polarized plane wave. The supraspinatus human tendon was taken as an object for theoretical modeling. The morphological features of the studied tissue were considered for a system of collagen fiber bundles embedded in a carbohydrate matrix. The latter one is a mixture of glycosaminoglycans and proteoglycans. Age-caused changes of the fibers and matrix influence on the spectral dependence of optical anisotropy spectrum.

Mikhailova, Alyona D.; Ermolenko, Sergey B.; Zimnyakov, Dmitry A.; Angelsky, Oleg V.

2009-10-01

176

Slope analysis of the optic disc in eyes with ocular hypertension and early normal tension glaucoma by confocal scanning laser ophthalmoscope  

Microsoft Academic Search

AIMSTo determine whether quantitative differences in sector based slope can differentiate between eyes with ocular hypertension with and without glaucomatous disc changes and eyes with normal tension glaucoma with glaucomatous disc changes.METHODSSeventy six eyes with ocular hypertension or early glaucomatous disc changes were consecutively categorised into three groups: 22 eyes with ocular hypertension and no glaucomatous disc changes (OHND); 35

J Dong; E Chihara

2001-01-01

177

Optical characters and texture maps of skin and the aging mechanism by use of multiphoton microscopy and optical coherence tomography  

NASA Astrophysics Data System (ADS)

Cutaneous aging is a complicated biological process affecting different constituents of skin, which can be divided into two types: the chronological aging and the photo-aging. The two cutaneous aging processes often co-exist accompanying with each other. The effects are often overlapped including changes in epithelium and dermis. The degeneration of collagen is a major factor in dermal alteration with aging. In this study, multiphoton microscopy (MPM) with its high resolution imaging and optical coherence tomography (OCT) with its depth resolved imaging were used to study the anti-aging dermatology in vivo. It was attempted to make the optical parameter and texture feature to evaluate the process of aging skin using mathematical image processing. The links among optical parameter, spectrum and texture feature in collagen with aging process were established to uncover mechanism of aging skin.

Wu, Shulian; Li, Hui; Zhang, Xiaoman; Huang, Yudian; Xu, Xiaohui

2012-03-01

178

Morning glory disc anomaly, midline cranial defects and abnormal carotid circulation: an association worth looking for  

Microsoft Academic Search

We report on a 4-year-old boy who presented to the ophthalmology department for assessment of convergent strabismus. Ophthalmic examination showed a left morning glory optic disc anomaly and retinal detachment. Plain films obtained for investigation of short stature prior to ophthalmic examination revealed delayed bone age. Ophthalmological findings prompted CT and MRI imaging and angiographic investigations. Midline cranial defects and

Boon Long Quah; Jill Hamilton; Susan Blaser; Elise Héon; Nasrin N. Tehrani

2005-01-01

179

Alteration of lunar optical properties: age and composition effects.  

PubMed

A model for lunar surface processes is presented which explains the main albedo and color contrasts and the temporal changes in these optical properties. Evidence from Apollo 11 and Apollo 12 samples and telescopic spectral reflectivity measurements indicates that the maria are similar in mineralogy on a regional scale and that the highlands are consistent with an anorthositic-gabbro composition. Bright craters and rays in both regions expose materials that are relatively crystalline compared with their backgrounds, which are richer in dark glass. With age, bright craters and rays in the maria darken in place by meteorite impact-induced vitrification and mixing with the surrounding material. Highland bright craters and rays may, however, darken primarily through regional contamination by iron- and titanium-rich mare material. PMID:17734782

Adams, J B; McCord, T B

1971-02-12

180

An Analysis of Burst Disc Pressure Instability  

SciTech Connect

During the development stage of the 1X Acorn burst disc, burst pressure test results exhibited an unexpected increase of 8 to 14% over times of 90--100 days from initial fabrication. This increase is a concern where design constraints require stability. The disc material, 316L stainless steel sheet, is formed to a dome-like geometry and scored to produce a thin-walled, high-strength ligament. The fracture events controlling burst occur in that ligament. Thus it has been characterized both for tensile properties and microstructure through nanoindentation, magnetic measurements, optical and transmission electron microscopy. These results compare favorably with finite element simulation of the properties of the ligament. The ligament exhibits a highly heterogeneous microstructure; its small volume and microstructural heterogeneity make it difficult to identify which microstructural feature controls fracture and hence burst pressure. Bulk mechanical test specimens were fabricated to emulate mid-ligament properties, and aged at both room and elevated temperatures to characterize and accelerate the temporal behavior of the burst disc. Property changes included yield and ultimate tensile strength increases, and fracture strain decreases with aging. Specimens were subjected to a reversion anneal identical to that given the burst disc to eliminate the martensite phase formed during rolling. Reversion-annealed samples exhibited no change in properties in room temperature or accelerated aging, showing that the reversion-anneal eliminated the aging phenomenon. Aging was analyzed in terms of diffusion controlled precipitate growth kinetics, showing that carbon migration to dislocations is consistent with the strength increases. A vacancy-assisted diffusion mechanism for carbon transport is proposed, giving rise to rapid aging, which replaces interstitial carbon diffusion until excess vacancies from deformation are consumed. Mechanical activation parameters in stress relaxation were measured, indicating that the deformation structures formed at high strains typical of the score ligament are resistant to annealing, and mimic the behavior of a thermal obstacles. This model also qualitatively explains the different rates of aging resulting from a range of levels of cold work.

S. L. Robinson; B. C. Odegard, Jr.; N. r. Moody; S. H. Goods

2000-06-01

181

No Acceleration of Intervertebral Disc Degeneration after a Single Injection of Bupivacaine in Young Age Group with Follow-Up of 5 Years  

PubMed Central

Study Design Prospective study of changes in intervertebral disc degeneration after injection of bupivacaine. Purpose To examine whether injection of bupivacaine into human intervertebral discs accelerates their degeneration. Overview of Literature Bupivacaine is commonly used for therapy and diagnosis of discogenic low back pain. However, several in vitro studies have reported toxic effects of bupivacaine to disc cells. We sought to evaluate whether this finding is clinically relevant. Methods We selected 46 patients with low back pain who showed disc degeneration at only one level (L4-L5 or L5-S1) on magnetic resonance imaging (MRI) (discography group, n=18), discoblock group (injection of bupivacaine, n=18), and a control group, n=10). There were no significant differences in baseline characteristics across the 3 groups. The two experimental groups underwent either discography or anesthetic discoblock, respectively. All three groups were followed up 5 years after the examination. Results At 5 years follow-up, there was no significant difference in the rate of disc degeneration among the 3 groups (p>0.1). Moreover, X-ray images showed that there was no significant difference in disc height, range of motion, or translation between flex and extension position (p>0.1). Conclusions In conclusion, radiologic and MRI findings did not show acceleration of intervertebral disc degeneration at 5 years after a single injection of bupivacaine into human discs. PMID:24066217

Inoue, Gen; Orita, Sumihisa; Eguchi, Yawara; Ochiai, Nobuyasu; Kishida, Shunji; Kuniyoshi, Kazuki; Nakamura, Junichi; Aoki, Yasuchika; Ishikawa, Tetsuhiro; Miyagi, Masayuki; Kamoda, Hiroto; Suzuki, Miyako; Takaso, Masashi; Toyone, Tomoaki; Kubota, Gou; Sakuma, Yoshihiro; Oikawa, Yasuhiro; Inage, Kazuhide; Sainoh, Takeshi; Takahashi, Kazuhisa

2013-01-01

182

Blu-ray Disc\\/Digital Versatile Disc Recording and Reproducing Compatible Use Technology in the 2nd Generation Pick Up for Blu-ray Disc  

Microsoft Academic Search

We developed a 2nd generation pick up for the Blu-ray disc (BD), which makes possible recording and reproducing on both BD and digital versatile disc (DVD), and has a size for audio and visual (AV) and personal computer (PC) applications. These properties are realized by a single objective lens and a newly developed hologram element. The next generation optical disc

Ichiro Morishita; Hiroyuki Shindo; Noriyoshi Takeya; Hoseop Jeong; Yonghan Yoon; Incheol Chang; Hyungjin Kim; Dongwoo Lee; Chonsu Kyong

2004-01-01

183

Fast and automatic algorithm for optic disc extraction in retinal images using principle-component-analysis-based preprocessing and curvelet transform.  

PubMed

Optic disc or optic nerve (ON) head extraction in retinal images has widespread applications in retinal disease diagnosis and human identification in biometric systems. This paper introduces a fast and automatic algorithm for detecting and extracting the ON region accurately from the retinal images without the use of the blood-vessel information. In this algorithm, to compensate for the destructive changes of the illumination and also enhance the contrast of the retinal images, we estimate the illumination of background and apply an adaptive correction function on the curvelet transform coefficients of retinal images. In other words, we eliminate the fault factors and pave the way to extract the ON region exactly. Then, we detect the ON region from retinal images using the morphology operators based on geodesic conversions, by applying a proper adaptive correction function on the reconstructed image's curvelet transform coefficients and a novel powerful criterion. Finally, using a local thresholding on the detected area of the retinal images, we extract the ON region. The proposed algorithm is evaluated on available images of DRIVE and STARE databases. The experimental results indicate that the proposed algorithm obtains an accuracy rate of 100% and 97.53% for the ON extractions on DRIVE and STARE databases, respectively. PMID:23455998

Shahbeig, Saleh; Pourghassem, Hossein

2013-01-01

184

Percutaneous diode laser disc nucleoplasty  

NASA Astrophysics Data System (ADS)

The treatment of herniated disc disease (HNP) over the years involved different miniinvasive surgical options. The classical microsurgical approach has been substituted over the years both by endoscopic approach in which is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc nucleoplasty. In the last ten years, the percutaneous laser disc nucleoplasty have been done worldwide in more than 40000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by the disc protrusion pressing against the nerve root, a 980 nm Diode laser introduced via a 22G needle under X-ray guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Material and method: to date, 130 patients (155 cases) suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Eightyfour (72%) males and 46 (28%) females had a percutaneous laser disc nucleoplasty. The average age of patients operated was 48 years (22 - 69). The level of disc removal was L3/L4 in 12 cases, L4/L5 in 87 cases and L5/S1 in 56 cases. Two different levels were treated at the same time in 25 patients. Results: the success rate at a minimum follow-up of 6 months was 88% with a complication rate of 0.5%.

Menchetti, P. P.; Longo, Leonardo

2004-09-01

185

Adaptive optics-assisted optical coherence tomography for imaging of patients with age related macular degeneration  

NASA Astrophysics Data System (ADS)

We developed an optical coherence tomography (OCT) prototype with a sample arm that uses a 3.4 mm beam, which is considerably larger than the 1.2 to 1.5 mm beam that is used in commercialized OCT systems. The system is equipped with adaptive optics (AO), and to distinguish it from traditional AO-OCT systems with a larger 6 mm beam we have coined this concept AO-assisted OCT. Compared to commercialized OCT systems, the 3.4 mm aperture combined with AO improves light collection efficiency and imaging lateral resolution. In this paper, the performance of the AOa-OCT system was compared to a standard OCT system and demonstrated for imaging of age-related macular degeneration (AMD). Measurements were performed on the retinas of three human volunteers with healthy eyes and on one eye of a patient diagnosed with AMD. The AO-assisted OCT system imaged retinal structures of healthy human eyes and a patient eye affected by AMD with higher lateral resolution and a 9° by 9° field of view. This combination of a large isoplanatic patch and high lateral resolution can be expected to fill a gap between standard OCT with a 1.2 mm beam and conventional AO-OCT with a 6 mm beam and a 1.5° by 1.5° isoplanatic patch.

Sudo, Kenta; Cense, Barry

2013-03-01

186

Rapid evolution of the innermost dust disc of protoplanetary discs surrounding intermediate-mass stars  

NASA Astrophysics Data System (ADS)

We derived the intermediate-mass (?1.5-7 M?) disc fraction (IMDF) in the near-infrared JHK photometric bands as well as in the mid-infrared (MIR) bands for young clusters in the age range of 0 to ˜10 Myr. From the JHK IMDF, the lifetime of the innermost dust disc (˜0.3 au; hereafter the K disc) is estimated to be ˜3 Myr, suggesting a stellar mass (M*) dependence of K-disc lifetime (?1.5-7 M?). However, from the MIR IMDF, the lifetime of the inner disc (˜5 au; hereafter the MIR disc) is estimated to be ˜6.5 Myr, suggesting a very weak stellar mass dependence (M*). The much shorter K-disc lifetime compared to the MIR-disc lifetime for intermediate-mass (IM) stars suggests that IM stars with transition discs, which have only MIR excess emission but no K-band excess emission, are more common than classical Herbig Ae/Be stars, which exhibit both. We suggest that this prominent early disappearance of the K disc for IM stars is due to dust settling/growth in the protoplanetary disc, and it could be one of the major reasons for the paucity of close-in planets around IM stars.

Yasui, Chikako; Kobayashi, Naoto; Tokunaga, Alan T.; Saito, Masao

2014-08-01

187

Intra- and inter-observer variation of optic nerve head measurements in glaucoma suspects using disc-data  

Microsoft Academic Search

The aim of this study was to determine the intra- and inter-observer variation in the use of a system designed for exact measurements from standard optic nerve head photographs. The commercially available system consisted of a colour CCD Videocamera, a dedicated frame grabber and customised software run on a IBM AT compatible computer. Masked measurements were made 3 times by

Jörg Stürmer; Darmalingam Poinoosawmy; David C. Broadway; Roger A. Hitchings

1992-01-01

188

A study of axonal degeneration in the optic nerves of aging mice  

NASA Technical Reports Server (NTRS)

The optic nerves of C57BL/6J mice ranging from 3 to 30 months were examined by electron microscopy. At all ages investigated, optic nerve axons contained enlarged mitochondria with abnormal cristae. With increasing age, a large number of necrotic axons were observed and were in the process of being phagocytized. The abnormal mitochondria may represent preliminary changes that eventually lead to necrosis of the axon.

Johnson, J. E., Jr.; Philpott, D. E.; Miquel, J.

1978-01-01

189

Study of the shape of an optical window in a super-resolution state by electromagnetic-thermal coupled simulation: Effects of melting of an active layer in an optical disc  

SciTech Connect

We performed a multi-physics simulation for the propagation of electromagnetic waves and heat conduction in a super-resolution optical disc that includes an active layer of InSb. Because the change in the optical constant of InSb due to the phase transition is taken into account, the melting of the active layer can be realistically simulated in our calculation. It was found that in the case of an incident light power (P) of 2 mW, a profile of the electric field intensity transmitted through the InSb layer has an asymmetric shape with a narrow peak. This beam-narrowing was suggested to be an essential mechanism of the super-resolution, because a narrower light beam allows the detection of a smaller pit structure than the optical diffraction limit. This beam-narrowing was found to be originating from a small molten region produced in the InSb layer, which works as a mask for light exposure.

Sano, Haruyuki, E-mail: h-sano@ishikawa-nct.ac.jp [Ishikawa National College of Technology, Kitacyujo, Tsubata, Ishikawa 929-0392 (Japan); Shima, Takayuki; Kuwahara, Masashi [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565 (Japan); Fujita, Yoshiya; Uchiyama, Munehisa; Aono, Yoshiyuki [Pulstec Industrial Co., Ltd., 7000-35, Nakagawa, Hosoe-cho, Kita-ku, Hamamatsu 431-1304 (Japan)

2014-04-21

190

ON THE AGE AND METALLICITY ESTIMATION OF SPIRAL GALAXIES USING OPTICAL AND NEAR-INFRARED PHOTOMETRY  

E-print Network

ON THE AGE AND METALLICITY ESTIMATION OF SPIRAL GALAXIES USING OPTICAL AND NEAR-INFRARED PHOTOMETRY-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming headinggs: galaxies: abundances -- galaxies: evolution -- galaxies: photometry -- galaxies: spiral

Lee, Hyun-chul

191

Quaternary Science Reviews 23 (2004) 11731182 Optical and radiocarbon ages of stacked paleosols and dune sands  

E-print Network

, because radiocarbon dating of buried soil humus provides limiting ages for eolian sand above or below resolution of dune field chronology than is possible with radiocarbon dating of soil organic matter. AlthoughQuaternary Science Reviews 23 (2004) 1173­1182 Optical and radiocarbon ages of stacked paleosols

Loope, David B.

192

Autonomous Optical Sensor System for the Monitoring of Nitrogen Dioxide from Aging Rocket Propellant  

Microsoft Academic Search

An optical sensor system has been developed for the autonomous monitoring of NOâ evolution in energetic material aging studies. The system is minimally invasive, requiring only the presence of a small sensor film within the aging chamber. The sensor material is a perylene\\/PMMA film that is excited by a blue LED light source and the fluorescence detected with a CCD

TRISHA D. COX; SEEMA SINGH; JOHN A. HUNTER; GARY D. JONES; MICHAEL B. SINCLAIR; LAUREN E. S. ROHWER; PHILLIP I. POHL; WILLIAM ANDRZEJEWSKI; DARRYL Y. SASAKI

2001-01-01

193

Blu-ray Disc/Digital Versatile Disc Recording and Reproducing Compatible Use Technology in the 2nd Generation Pick Up for Blu-ray Disc  

NASA Astrophysics Data System (ADS)

We developed a 2nd generation pick up for the Blu-ray disc (BD), which makes possible recording and reproducing on both BD and digital versatile disc (DVD), and has a size for audio and visual (AV) and personal computer (PC) applications. These properties are realized by a single objective lens and a newly developed hologram element. The next generation optical disc system, which is expected to enable over 15 GB recording and reproducing on an optical disc, is also expected to record and reproduce on DVD or compact disc (CD), using one pick up. In order to satisfy such demand, we have developed an objective lens with a long working distance and proposed a BD/DVD/CD compatible use technology. This paper reports the details of how we achieved a proper sized AV/PC for common use, BD/DVD recording and reproducing compatible use and the dual layer disc in the 2nd generation pick up for BD.

Morishita, Ichiro; Shindo, Hiroyuki; Takeya, Noriyoshi; Jeong, Hoseop; Yoon, Yonghan; Chang, Incheol; Kim, Hyungjin; Lee, Dongwoo; Kyong, Chonsu

2004-07-01

194

Counterrotating stars in simulated galaxy discs  

NASA Astrophysics Data System (ADS)

Counterrotating stars in disc galaxies are a puzzling dynamical feature whose origin has been ascribed to either satellite accretion events or to disc instabilities triggered by deviations from axisymmetry. We use a cosmological simulation of the formation of a disc galaxy to show that counterrotating stellar disc components may arise naturally in hierarchically clustering scenarios even in the absence of merging. The simulated disc galaxy consists of two coplanar, overlapping stellar components with opposite spins: an inner counterrotating bar-like structure made up mostly of old stars surrounded by an extended, rotationally supported disc of younger stars. The opposite-spin components originate from material accreted from two distinct filamentary structures which at turn around, when their net spin is acquired, intersect delineating a `V'-like structure. Each filament torques the other in opposite directions; the filament that first drains into the galaxy forms the inner counterrotating bar, while material accreted from the other filament forms the outer disc. Mergers do not play a substantial role and most stars in the galaxy are formed in situ; only 9 per cent of all stars are contributed by accretion events. The formation scenario we describe here implies a significant age difference between the co- and counterrotating components, which may be used to discriminate between competing scenarios for the origin of counterrotating stars in disc galaxies.

Algorry, David G.; Navarro, Julio F.; Abadi, Mario G.; Sales, Laura V.; Steinmetz, Matthias; Piontek, Franziska

2014-02-01

195

Percutaneous cervical disc decompression  

Microsoft Academic Search

Background  Cervical disc nucleoplasty is a significant and clinically demonstrated innovation in percutaneous disc decompression in case\\u000a of non-herniated disc protrusions or prolpase. It allows a percutaneous decompression via a 19-gauge needle under utilization\\u000a of the Coblation® technique and under C-arm control. Until now the patients suffering of a cervicobrachialgia in cause of a disc prolapse had\\u000a only the therapeutical solution

Klaus Birnbaum

2009-01-01

196

Automotive disc brake squeal  

Microsoft Academic Search

Disc brake squeal remains an elusive problem in the automotive industry. Since the early 20th century, many investigators have examined the problem with experimental, analytical, and computational techniques, but there is as yet no method to completely suppress disc brake squeal. This paper provides a comprehensive review and bibliography of works on disc brake squeal. In an effort to make

N. M. Kinkaid; O. M. O'Reilly; P. Papadopoulos

2003-01-01

197

Turbine disc sealing assembly  

DOEpatents

A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

Diakunchak, Ihor S.

2013-03-05

198

Artificial Discs for Lumbar and Cervical Degenerative Disc Disease –Update  

PubMed Central

Executive Summary Objective To assess the safety and efficacy of artificial disc replacement (ADR) technology for degenerative disc disease (DDD). Clinical Need Degenerative disc disease is the term used to describe the deterioration of 1 or more intervertebral discs of the spine. The prevalence of DDD is roughly described in proportion to age such that 40% of people aged 40 years have DDD, increasing to 80% among those aged 80 years or older. Low back pain is a common symptom of lumbar DDD; neck and arm pain are common symptoms of cervical DDD. Nonsurgical treatments can be used to relieve pain and minimize disability associated with DDD. However, it is estimated that about 10% to 20% of people with lumbar DDD and up to 30% with cervical DDD will be unresponsive to nonsurgical treatments. In these cases, surgical treatment is considered. Spinal fusion (arthrodesis) is the process of fusing or joining 2 bones and is considered the surgical gold standard for DDD. Artificial disc replacement is the replacement of the degenerated intervertebral disc with an artificial disc in people with DDD of the lumbar or cervical spine that has been unresponsive to nonsurgical treatments for at least 6 months. Unlike spinal fusion, ADR preserves movement of the spine, which is thought to reduce or prevent the development of adjacent segment degeneration. Additionally, a bone graft is not required for ADR, and this alleviates complications, including bone graft donor site pain and pseudoarthrosis. It is estimated that about 5% of patients who require surgery for DDD will be candidates for ADR. Review Strategy The Medical Advisory Secretariat conducted a computerized search of the literature published between 2003 and September 2005 to answer the following questions: What is the effectiveness of ADR in people with DDD of the lumbar or cervical regions of the spine compared with spinal fusion surgery? Does an artificial disc reduce the incidence of adjacent segment degeneration (ASD) compared with spinal fusion? What is the rate of major complications (device failure, reoperation) with artificial discs compared with surgical spinal fusion? One reviewer evaluated the internal validity of the primary studies using the criteria outlined in the Cochrane Musculoskeletal Injuries Group Quality Assessment Tool. The quality of concealment allocation was rated as: A, clearly yes; B, unclear; or C, clearly no. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to evaluate the overall quality of the body of evidence (defined as 1 or more studies) supporting the research questions explored in this systematic review. A random effects model meta-analysis was conducted when data were available from 2 or more randomized controlled trials (RCTs) and when there was no statistical and or clinical heterogeneity among studies. Bayesian analyses were undertaken to do the following: Examine the influence of missing data on clinical success rates; Compute the probability that artificial discs were superior to spinal fusion (on the basis of clinical success rates); Examine whether the results were sensitive to the choice of noninferiority margin. Summary of Findings The literature search yielded 140 citations. Of these, 1 Cochrane systematic review, 1 RCT, and 10 case series were included in this review. Unpublished data from an RCT reported in the grey literature were obtained from the manufacturer of the device. The search also yielded 8 health technology assessments evaluating ADR that are also included in this review. Six of the 8 health technology assessments concluded that there is insufficient evidence to support the use of either lumbar or cervical ADR. The results of the remaining 2 assessments (one each for lumbar and cervical ADR) led to a National Institute for Clinical Excellence guidance document supporting the safety and effectiveness of lumbar and cervical ADR with the proviso that an ongoing audit of all clinical outcomes be undertaken owing to a lack of long-term outcome data from clinical trials. Regard

2006-01-01

199

A revised burial dose estimation procedure for optical dating of youngand modern-age sediments  

USGS Publications Warehouse

The presence of genuinely zero-age or near-zero-age grains in modern-age and very young samples poses a problem for many existing burial dose estimation procedures used in optical (optically stimulated luminescence, OSL) dating. This difficulty currently necessitates consideration of relatively simplistic and statistically inferior age models. In this study, we investigate the potential for using modified versions of the statistical age models of Galbraith et??al. [Galbraith, R.F., Roberts, R.G., Laslett, G.M., Yoshida, H., Olley, J.M., 1999. Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: Part I, experimental design and statistical models. Archaeometry 41, 339-364.] to provide reliable equivalent dose (De) estimates for young and modern-age samples that display negative, zero or near-zero De estimates. For this purpose, we have revised the original versions of the central and minimum age models, which are based on log-transformed De values, so that they can be applied to un-logged De estimates and their associated absolute standard errors. The suitability of these 'un-logged' age models is tested using a series of known-age fluvial samples deposited within two arroyo systems from the American Southwest. The un-logged age models provide accurate burial doses and final OSL ages for roughly three-quarters of the total number of samples considered in this study. Sensitivity tests reveal that the un-logged versions of the central and minimum age models are capable of producing accurate burial dose estimates for modern-age and very young (<350??yr) fluvial samples that contain (i) more than 20% of well-bleached grains in their De distributions, or (ii) smaller sub-populations of well-bleached grains for which the De values are known with high precision. Our results indicate that the original (log-transformed) versions of the central and minimum age models are still preferable for most routine dating applications, since these age models are better suited to the statistical properties of typical single-grain and multi-grain single-aliquot De datasets. However, the unique error properties of modern-age samples, combined with the problems of calculating natural logarithms of negative or zero-Gy De values, mean that the un-logged versions of the central and minimum age models currently offer the most suitable means of deriving accurate burial dose estimates for very young and modern-age samples. ?? 2009 Elsevier Ltd. All rights reserved.

Arnold, L.J.; Roberts, R.G.; Galbraith, R.F.; DeLong, S.B.

2009-01-01

200

Percutaneous Treatment of Intervertebral Disc Herniation  

Microsoft Academic Search

\\u000a Disc herniation is defined as rupture of the fibrocartilagenous annulus fibrosus that surrounds the intervertebral disc, associated\\u000a with the release of the central gelatinous nucleus pulposus. Most herniations take place in the lumbar area of the spine.\\u000a They occur more frequently in middle aged and older men, especially those involved in strenuous physical activity. They cause\\u000a physical disability with significant

Xavier Buy; Afshin Gangi; Stéphane Guth; Ali Guermazi

201

Lumbar Disc Degenerative Disease: Disc Degeneration Symptoms and Magnetic Resonance Image Findings  

PubMed Central

Study Design Cross sectional and observational. Purpose To evaluate the different aspects of lumbar disc degenerative disc disease and relate them with magnetic resonance image (MRI) findings and symptoms. Overview of Literature Lumbar disc degenerative disease has now been proven as the most common cause of low back pain throughout the world. It may present as disc herniation, lumbar spinal stenosis, facet joint arthropathy or any combination. Presenting symptoms of lumbar disc degeneration are lower back pain and sciatica which may be aggravated by standing, walking, bending, straining and coughing. Methods This study was conducted from January 2012 to June 2012. Study was conducted on the diagnosed patients of lumbar disc degeneration. Diagnostic criteria were based upon abnormal findings in MRI. Patients with prior back surgery, spine fractures, sacroiliac arthritis, metabolic bone disease, spinal infection, rheumatoid arthritis, active malignancy, and pregnancy were excluded. Results During the targeted months, 163 patients of lumbar disc degeneration with mean age of 43.92±11.76 years, came into Neurosurgery department. Disc degeneration was most commonly present at the level of L4/L5 105 (64.4%).Commonest types of disc degeneration were disc herniation 109 (66.9%) and lumbar spinal stenosis 37 (22.7%). Spondylolisthesis was commonly present at L5/S1 10 (6.1%) and associated mostly with lumbar spinal stenosis 7 (18.9%). Conclusions Results reported the frequent occurrence of lumbar disc degenerative disease in advance age. Research efforts should endeavor to reduce risk factors and improve the quality of life. PMID:24353850

Saleem, Shafaq; Rehmani, Muhammad Asim Khan; Raees, Aisha; Alvi, Arsalan Ahmad; Ashraf, Junaid

2013-01-01

202

Annulo-nucleoplasty using Disc-FX in the management of lumbar disc pathology: Early results  

PubMed Central

Background Back pain due to Lumbar Disc Disease is a major clinical problem. The treatment options range from physiotherapy to fusion surgery. A number of minimally invasive procedures have also been developed in the recent past for its management. Disc-FX is a new minimally invasive technique that combines percutaneous discectomy, nuclear ablation and annular modification. Literature on its role in the management of lumbar disc pathology is scarce. Methods We included 24 consecutive patients who underwent the Disc-FX for back pain due to lumbar disc pathology non-responsive to non-operative treatment for a period of at least 6 months. Based on Magnetic Resonance Imaging (MRI) these patients fell into 2 groups – those with degenerative disc disease (DDD) (n = 12) and those with a contained lumbar disc herniation (CLDH)(n = 12). They were evaluated using the Visual analogue scale (VAS), Oswestry Disability Index (ODI) and Short Form-36 (SF-36) scores preoperatively and postoperatively. Results The mean age was 37.9 years (21-53 years). There were 17 males and 7 females. One patient in each subgroup was excluded from the final evaluation. Significant improvement was seen in all outcome measures. The overall rate of reintervention for persistent symptoms was 18.18% (4/22); in the CLDH subgroup, it was 36.36% (4/11). Conclusions and level of evidence Early results after the Disc-FX procedure suggest that it s a reasonable treatment option for patients with back pain due to lumbar disc disease, especially for those with DDD who fail conservative treatment. It could be an alternative to procedures like fusion or disc replacement. This study presents Level IV evidence. Clinical relevance We feel that our study establishes Disc-FX as a modality of treating symptomatic lumbar disc disease due to DDD. However, longer term prospective studies are needed to prove this and to evaluate its role in the treatment of patients with CLDH. PMID:25694914

Kumar, Aravind; Siddharth M, Shah; Sambhav P, Shah; Tan, Justin

2014-01-01

203

Changes in diffusion path length with old age in diffuse optical tomography  

NASA Astrophysics Data System (ADS)

Diffuse, optical near infrared imaging is increasingly being used in various neurocognitive contexts where changes in optical signals are interpreted through activation maps. Statistical population comparison of different age or clinical groups rely on the relative homogeneous distribution of measurements across subjects in order to infer changes in brain function. In the context of an increasing use of diffuse optical imaging with older adult populations, changes in tissue properties and anatomy with age adds additional confounds. Few studies investigated these changes with age. Duncan et al. measured the so-called diffusion path length factor (DPF) in a large population but did not explore beyond the age of 51 after which physiological and anatomical changes are expected to occur [Pediatr. Res. 39(5), 889-894 (1996)]. With increasing interest in studying the geriatric population with optical imaging, we studied changes in tissue properties in young and old subjects using both magnetic resonance imaging (MRI)-guided Monte-Carlo simulations and time-domain diffuse optical imaging. Our results, measured in the frontal cortex, show changes in DPF that are smaller than previously measured by Duncan et al. in a younger population. The origin of these changes are studied using simulations and experimental measures.

Bonnéry, Clément; Leclerc, Paul-Olivier; Desjardins, Michèle; Hoge, Rick; Bherer, Louis; Pouliot, Philippe; Lesage, Frédéric

2012-05-01

204

Changes in diffusion path length with old age in diffuse optical tomography.  

PubMed

Diffuse, optical near infrared imaging is increasingly being used in various neurocognitive contexts where changes in optical signals are interpreted through activation maps. Statistical population comparison of different age or clinical groups rely on the relative homogeneous distribution of measurements across subjects in order to infer changes in brain function. In the context of an increasing use of diffuse optical imaging with older adult populations, changes in tissue properties and anatomy with age adds additional confounds. Few studies investigated these changes with age. Duncan et al. measured the so-called diffusion path length factor (DPF) in a large population but did not explore beyond the age of 51 after which physiological and anatomical changes are expected to occur [Pediatr. Res. 39(5), 889-894 (1996)]. With increasing interest in studying the geriatric population with optical imaging, we studied changes in tissue properties in young and old subjects using both magnetic resonance imaging (MRI)-guided Monte-Carlo simulations and time-domain diffuse optical imaging. Our results, measured in the frontal cortex, show changes in DPF that are smaller than previously measured by Duncan et al. in a younger population. The origin of these changes are studied using simulations and experimental measures. PMID:22612125

Bonnéry, Clément; Leclerc, Paul-Olivier; Desjardins, Michèle; Hoge, Rick; Bherer, Louis; Pouliot, Philippe; Lesage, Frédéric

2012-05-01

205

Optical properties of neonatal skin measured in vivo as a function of age and skin pigmentation  

NASA Astrophysics Data System (ADS)

Knowledge of the optical properties of neonatal skin is invaluable when developing new, or improving existing optical techniques for use at the neonatal intensive care. In this article, we present in vivo measurements of the absorption ?a and reduced scattering coefficient ?s' of neonatal skin between 450 and 600 nm and assess the influence of age and skin pigmentation on the optical properties. The optical properties were measured using a spatially resolved, steady state diffuse reflectance spectroscopy setup, combined with a modified spatially resolved diffusion model. The method was validated on phantoms with known values for the absorption and reduced scattering coefficient. Values of ?a and ?s' were obtained from the skin at four different body locations (forehead, sternum, hand, and foot) of 60 neonates with varying gestational age, postnatal age, and skin pigmentation. We found that ?a ranged from 0.02 to 1.25 mm-1 and ?s' was in the range of 1 to 2.8 mm-1 (5th to 95th percentile of the patient population), independent of body location. In contrast to previous studies, no to very weak correlation was observed between the optical properties and gestational maturity, but a strong dependency of the absorption coefficient on postnatal age was found for dark skinned patients.

Bosschaart, Nienke; Mentink, Rosaline; Kok, Joke H.; van Leeuwen, Ton G.; Aalders, Maurice C. G.

2011-09-01

206

A corona plus disc model for Cygnus X-1  

NASA Astrophysics Data System (ADS)

The author has constructed a model for Cygnus X-1 consisting of an outer optically thick and geometrically thin disc, an inner optically thin and geometrically thick disc and above it, a coronal region that scatters photons from the outer disc to the inner disc, where they are inverse comptonized. This model reproduces the observed spectrum of Cygnus X-1 quite well. Using a local stability criterion, and taking into account the contribution of the turbulent pressure pulsations in hydrostatic equilibrium, it is shown that the inner region is thermally unstable against small perturbations in the radial direction. For the outer disc it is seen that instability sets in the disc as long as the radiation pressure exceeds a critical value. This value, however, depends on the turbulent Mach number.

Meirelles Filho, C.

1987-12-01

207

Spectroscopic Parameters of Lumbar Intervertebral Disc Material  

NASA Astrophysics Data System (ADS)

There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 ?m thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the needle can give additional information of needle position, assuring the needle tip is directed into intervertebral disc material. Spectroscopic analysis of intervertebral disc removed during open surgery, creates background for further investigation on intervertebral disc degeneration spectral classification.

Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

2009-06-01

208

Episodic accretion in magnetically layered protoplanetary discs  

E-print Network

We study protoplanetary disc evolution assuming that angular momentum transport is driven by gravitational instability at large radii, and magnetohydrodynamic (MHD) turbulence in the hot inner regions. At radii of the order of 1 AU such discs develop a magnetically layered structure, with accretion occurring in an ionized surface layer overlying quiescent gas that is too cool to sustain MHD turbulence. We show that layered discs are subject to a limit cycle instability, in which accretion onto the protostar occurs in bursts with an accretion rate of 10^{-5} solar masses / yr, separated by quiescent intervals where the accretion rate is 10^{-8} solar masses / yr. Such bursts could lead to repeated episodes of strong mass outflow in Young Stellar Objects. The transition to this episodic mode of accretion occurs at an early epoch (t < 1 Myr), and the model therefore predicts that many young pre-main-sequence stars should have low rates of accretion through the inner disc. At ages of a few Myr, the discs are up to an order of magnitude more massive than the minimum mass solar nebula, with most of the mass locked up in the quiescent layer of the disc at around 1 AU. The predicted rate of low mass planetary migration is reduced at the outer edge of the layered disc, which could lead to an enhanced probability of giant planet formation at radii of 1-3 AU.

Philip J. Armitage; Mario Livio; J. E. Pringle

2001-01-16

209

Optical aberrations of the human cornea as a function of age.  

PubMed

We investigated how the optical aberrations associated with the anterior surface of the human cornea change with age in a normal population. Aberrations were computed for a central part of the cornea (4, 5, and 6 mm in diameter) from the elevation data provided by a videokeratographic system. Measurements were obtained in 59 normal healthy, near-emmetropic [spherical equivalent lower than 2 diopters (D)] subjects of three age ranges: younger (20-30 years old), middle-aged (40-50 years old), and older (60-70 years old). The average corneal radius decreased with age and the cornea became more spherical. As a consequence, spherical aberration was significantly larger in the middle-aged and older corneas. Coma and other higher-order aberrations also were correlated with age. The root mean square of the wave aberration exhibited a linear positive correlation (P < 0.003) with age for the three ranges of pupil diameter. Despite a large intersubject variability, the average amount of aberration in the human cornea tends to increase moderately with age. However, this increase alone is not enough to explain the substantial reduction previously found in retinal image quality with age. The change in the aberrations of the lens with age and the possible loss of part of the balance between corneal and lenticular aberrations in youth may be the main factors responsible for the reduction of retinal image quality through the life span. PMID:11028517

Guirao, A; Redondo, M; Artal, P

2000-10-01

210

Twin disc gear tooth simulator  

Microsoft Academic Search

This report describes the results of an effort to develop a disc on disc test rig for evaluating lubricant load capacity. The goal of the program has been to develop a reliable disc on disc (or Twin Disc) test rig capable of providing more reliable and lower cost evaluation of lubricant load capacity than the Ryder gear test which is

Martin W. Eusepi; James F. Dill

1994-01-01

211

Childhood intervertebral disc calcification  

Microsoft Academic Search

Two cases of intervertebral disc calcification in children are reported. A 13-year-old boy presented with right subscapular pain radiating into the axilla with radiographic demonstration of multiple calcified intervertebral discs and a herniated fragment of calcified nucleus pulposus at T2–3. His condition improved with conservative therapy, and follow-up radiographic evaluation revealed resolution of the herniated calcified disc material. A second

B. Theo Mellion; John P. Laurent; William C. Watters

1993-01-01

212

50 GB read only memory disc with dual layer structure  

Microsoft Academic Search

Recently, a Blu-ray Disc (BD) has been proposed as a rewritable optical disc, in which HDTV digital data can be recorded for two hours or more. It has a capacity of about 25 GB with a size of 120 mm in diameter. It employs a blue laser of 405 nm wavelength and an objective lens with an NA of 0.85

M. Tsukuda; E. Ito; M. Tomiyama; S. Abe; S. Furumiya; E. Ohno

2002-01-01

213

The Evolution of Massive Disc Galaxies with Environment and Redshift  

Microsoft Academic Search

This thesis examines the evolution of massive disc galaxies as a function of cosmic time and environment by analysing a sample of luminous disc galaxies, located in the field and rich clusters at intermediate redshifts. The data utilised for this study are two-dimensional optical spectra obtained with the FORS2 instrument on the VLT, along with imaging from a variety of

Steven P. Bamford

2006-01-01

214

The effectiveness of percutaneous laser disc decompression for the prolapsed lumbar intervertebral disc  

NASA Astrophysics Data System (ADS)

Objective: to investigate the role of associated factors in the effectiveness of laser treatment for prolapsed lumber intervertebral disc. Method: 302 prolapsed lumber intervertebral discs in 212 patients were treated with percutaneous laser disc decompression (PLDD). Patients were followed up by 12month, the associated factors which affecting the effectiveness of treatment, ie age, duration of illness were analyzed. Results: Punctual Success rate was 100%. After 12 month's follow up, 86% successful outcomes were obtained, in which 93% successful outcomes were obtained in patients less than 50 years old, 92% successful outcomes was obtained in the patients whose duration of illness less than 1 year.

Mu, Ming Wei; Liu, Wei; Feng, Wei; Ma, Nan

2009-07-01

215

Aging Related Changes of Retina and Optic Nerve of Uromastyx aegyptia and Falco tinnunculus  

PubMed Central

Aging is a biological phenomenon that involves gradual degradation of the structure and function of the retina and optic nerve. To our knowledge, little is known about the aging-related ocular cell loss in avian (Falco tinnunculus) and reptilian species (Uromastyx aegyptia). A selected 90 animals of pup, middle, and old age U. aegyptia (reptilian) and F. tinnunculus (avian) were used. The retinae and optic nerves were investigated by light and transmission electron microscopy (TEM) and assessments of neurotransmitters, antioxidant enzymes (catalase, superoxide dismustase and glutathione s transferase), caspase-3 and -7, malonadialdhyde, and DNA fragmentation. Light and TEM observations of the senile specimens revealed apparent deterioration of retinal cell layers, especially the pigmented epithelium and photoreceptor outer segments. Their inclusions of melanin were replaced by lipofuscins. Also, vacuolar degeneration and demyelination of the optic nerve axons were detected. Concomitantly, there was a marked increase of oxidative stress involved reduction of neurotransmitters and antioxidant enzymes and an increase of lipid peroxidation, caspase-3 and -7, subG0/G1 apoptosis, and P53. We conclude that aging showed an inverse relationship with the neurotransmitters and antioxidant enzymes and a linear relationship of caspases, malondialdhyde, DNA apoptosis, and P53 markers of cell death. These markers reflected the retinal cytological alterations and lipofuscin accumulation within inner segments. PMID:24215233

2013-01-01

216

Dark Matter in Disc Galaxies  

E-print Network

Recent work on the mass distribution in spiral galaxies, using mainly HI observations, is reviewed. The principal problem is still to determine to what extent the dark matter is important in the inner parts of a galaxy, or in other words, how dominant is the self-gravitation of the disc. Studies of the shapes of rotation curves show that in detail there is sufficient individuality in spiral galaxies to prohibit the construction of ``Universal Rotation Curves''. A detailed account is given of the method of Athanassoula et al. (1987), where swing amplifier criteria are applied to set a range in the mass-to-light ratio of the disc. To restrict this range further, other methods might be useful. For a number of bright spirals the rotation curve drops just outside the optical image, but this feature by itself cannot constrain unambiguously the mass models. The use of velocity dispersions seems a promising way, though the observational problems are hard. Within the uncertainties, discs can be close to ``maximum'', even though a range of values cannot be excluded.

A. Bosma

1998-12-01

217

Autonomous Optical Sensor System for the Monitoring of Nitrogen Dioxide from Aging Rocket Propellant  

SciTech Connect

An optical sensor system has been developed for the autonomous monitoring of NO{sub 2} evolution in energetic material aging studies. The system is minimally invasive, requiring only the presence of a small sensor film within the aging chamber. The sensor material is a perylene/PMMA film that is excited by a blue LED light source and the fluorescence detected with a CCD spectrometer. Detection of NO{sub 2} gas is done remotely through the glass window of the aging chamber. Irreversible reaction of NO{sub 2} with perylene, producing the non-fluorescent nitroperylene, provides the optical sensing scheme. The rate of fluorescence intensity loss over time can be modeled using a numerical solution to the coupled diffusion and a nonlinear chemical reaction problem to evaluate NO{sub 2} concentration levels. The light source, spectrometer, spectral acquisition, and data processing were controlled through a Labivew program run by a laptop PC. Due to the long times involved with materials aging studies the system was designed to turn on, warm up, acquire data, power itself off, then recycle at a specific time interval. This allowed the monitoring of aging HE material over the period of several weeks with minimal power consumption and stable LED light output. Despite inherent problems with gas leakage of the aging chamber they were able to test the sensor system in the field under an accelerated aging study of rocket propellant. They found that the propellant evolved NO{sub 2} at a rate that yielded a concentration of between 10 and 100 ppm. The sensor system further revealed that the propellant, over an aging period of 25 days, evolves NO{sub 2} with cyclic behavior between active and dormant periods.

COX, TRISHA D.; SINGH, SEEMA; HUNTER, JOHN A.; JONES, GARY D.; SINCLAIR, MICHAEL B.; ROHWER, LAUREN E. S.; POHL, PHILLIP I.; ANDRZEJEWSKI, WILLIAM; SASAKI, DARRYL Y.

2001-09-01

218

High Response Twin-Objective Actuator with Radial Tilt Function for Blu-ray Disc Recorder  

Microsoft Academic Search

We have developed Blu-ray Disc (BD) optical pick-up with a twin-objective lens actuator which is compatible with compact disc (CD) and digital versatile disc (DVD) in the high-speed BD-read only memory (ROM) and BD Recorder. In order to readout CD and DVD in BD Recorder, we adopted twin-objective lens actuator in consideration of optical utilization efficiency, optical performance and insurance

Seok Jung Kim; Tae Youn Heor; Tae Kyung Kim; Young Man Ahn; Chong Sam Chung; Soo Han Park

2005-01-01

219

Proteomic Signature of the Murine Intervertebral Disc  

PubMed Central

Low back pain is the most common musculoskeletal problem and the single most common cause of disability, often attributed to degeneration of the intervertebral disc. Lack of effective treatment is directly related to our limited understanding of the pathways responsible for maintaining disc health. While transcriptional analysis has permitted initial insights into the biology of the intervertebral disc, complete proteomic characterization is required. We therefore employed liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) protein/peptide separation and mass spectrometric analyses to characterize the protein content of intervertebral discs from skeletally mature wild-type mice. A total of 1360 proteins were identified and categorized using PANTHER. Identified proteins were primarily intracellular/plasma membrane (35%), organelle (30%), macromolecular complex (10%), extracellular region (9%). Molecular function categorization resulted in three distinct categories: catalytic activity (33%), binding (molecule interactions) (29%), and structural activity (13%). To validate our list, we confirmed the presence of 14 of 20 previously identified IVD-associated markers, including matrix proteins, transcriptional regulators, and secreted proteins. Immunohistochemical analysis confirmed distinct localization patterns of select protein with the intervertebral disc. Characterization of the protein composition of healthy intervertebral disc tissue is an important first step in identifying cellular processes and pathways disrupted during aging or disease progression. PMID:25689066

McCann, Matthew R.; Patel, Priya; Frimpong, Agya; Xiao, Yizhi; Siqueira, Walter L.; Séguin, Cheryle A.

2015-01-01

220

Advances in susceptibility genetics of intervertebral degenerative disc disease.  

PubMed

The traditional view that the etiology of lumbar disc herniation is primarily due to age, gender, occupation, smoking and exposure to vehicular vibration dominated much of the last century. Recent research indicates that heredity may be largely responsible for the degeneration as well as herniation of intervertebral discs. Since 1998, genetic influences have been confirmed by the identification of several genes forms associated with disc degeneration. These researches are paving the way for a better understanding of the biologic mechanisms. Now, many researchers unanimously agree that lumbar disc herniation appears to be similar to other complex diseases, whose etiology has both environmental and hereditary influence, each with a part of contribution and relative risk. Then addressing the etiological of lumbar disc herniation, it is important to integrate heredity with the environment factors. For the purpose of this review, we have limited our discussion to several susceptibility genes associated with disc degeneration. PMID:18781226

Zhang, Yin'gang; Sun, Zhengming; Liu, Jiangtao; Guo, Xiong

2008-01-01

221

New DPD tracking servo method by signal processing for high-density ROM discs  

Microsoft Academic Search

Differential phase detection (DPD) is the most popular tracking error detection method for read-only optical discs (ROM discs). However, DPD tracking-error signals deteriorate for high-density discs such as over 30-GB Blu-ray discs (BDs) where zero-cross detection becomes inaccurate. To solve this problem, we propose a new zero-cross-detection-free DPD (ZF-DPD) method by applying the least-mean-square (LMS) algorithm adaptive equalizer. We experimentally

Junya Shiraishi; Tsutomu Maruyama; Yoshihiro Takemoto; Isao Ichimura; Shoei Kobayashi

2007-01-01

222

Discs gone with the wind?  

Microsoft Academic Search

We examine the conditions imposed on the vertical structure of accretion discs for them to exist. We find that a wind powered by a thermal instability exists in all discs with certain opacity laws. We find that for discs dominated by bremsstrahlung radiation, an inner hole develops below a certain accretion rate, and that for very low accretion rates, discs

G. Shaviv; D. Wickramasinghe; R. Wehrse

1999-01-01

223

An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils  

USGS Publications Warehouse

There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

Mahan, S.A.; Brown, D.J.

2007-01-01

224

Herniated Lumbar Disc  

MedlinePLUS

... be treated with nonprescription medications such as aspirin, ibuprofen, naproxen or acetaminophen. If you have severe persistent ... a result of disc herniation. These include asprin, ibuprofen, naproxen and a variety of prescription drugs. If ...

225

Artificial Disc Replacement  

MedlinePLUS

... each other. Most nucleus replacement devices are made of plastic-like (biopolymer) materials. One such material is called ... disc nucleus. Another design consists of a piece of a plastic-like material that coils around to fill the ...

226

Morphology of young and old cervical spine intervertebral disc tissues.  

PubMed

The intervertebral disc of the cervical spine undergoes degenerative changes during the aging process. Although many studies have reported the qualitative changes in the disc, methodology to quantify these changes is lacking. The present study was designed to quantify the geometrical variations of the nucleus pulposus, annulus fibrosus and uncovertebral joints. The age groups of specimens were classified as juvenile, adult and aged. Fresh intervertebral discs with adjacent vertebral bodies of the lower cervical spine of primates were isolated. The specimens were sectioned sequentially in a coronal plane. Sections were stained with Hematoxylin and Eosin, Verhoeff's, Safranin O, and Trichrome methods to distinguish the nucleus, annulus and uncovertebral joints. Histological images were examined using light microscopy and processed using a computer imaging program to trace the boundaries of the disc components. Dorsal-to-ventral depth and medial-to-lateral width of the nucleus pulposus, and its relative location to the annulus pulposus were also obtained. In the juvenile and adult discs, the nucleus appeared as a light opaque region with scattered notochordal cells with a clear distinction from the annulus region. In contrast, in the aged discs, the nucleus appeared as a dense region of amorphous, irregular collagen materials with less distinction from the annulus region. With the progression of aging, the dorsal-to-ventral depth of the nucleus decreased considerably compared to medial-to-lateral width. The uncovertebral joints were clear in the adult discs. The joints were less distinct in the aged discs and their size decreased. Quantification of three-dimensional geometrical variations will assist in better defining the disc tissue in the mathematical models. PMID:10834223

Kumaresan, S; Yoganandan, N; Pintar, F A; Macias, M; Cusick, J F

2000-01-01

227

Optic disc boundary segmentation from diffeomorphic demons registration of monocular fundus image sequences versus 3D visualization of stereo fundus image pairs for automated early stage glaucoma assessment  

NASA Astrophysics Data System (ADS)

Despite the current availability in resource-rich regions of advanced technologies in scanning and 3-D imaging in current ophthalmology practice, world-wide screening tests for early detection and progression of glaucoma still consist of a variety of simple tools, including fundus image-based parameters such as CDR (cup to disc diameter ratio) and CAR (cup to disc area ratio), especially in resource -poor regions. Reliable automated computation of the relevant parameters from fundus image sequences requires robust non-rigid registration and segmentation techniques. Recent research work demonstrated that proper non-rigid registration of multi-view monocular fundus image sequences could result in acceptable segmentation of cup boundaries for automated computation of CAR and CDR. This research work introduces a composite diffeomorphic demons registration algorithm for segmentation of cup boundaries from a sequence of monocular images and compares the resulting CAR and CDR values with those computed manually by experts and from 3-D visualization of stereo pairs. Our preliminary results show that the automated computation of CDR and CAR from composite diffeomorphic segmentation of monocular image sequences yield values comparable with those from the other two techniques and thus may provide global healthcare with a cost-effective yet accurate tool for management of glaucoma in its early stage.

Gatti, Vijay; Hill, Jason; Mitra, Sunanda; Nutter, Brian

2014-03-01

228

Bryan total disc arthroplasty: a replacement disc for cervical disc disease  

PubMed Central

Total disc arthroplasty is a new option in the treatment of cervical degenerative disc disease. Several types of cervical disc prostheses currently challenge the gold-standard discectomy and fusion procedures. This review describes the Bryan Cervical Disc System and presents the Bryan prosthesis, its indications, surgical technique, complications, and outcomes, as given in the literature. PMID:22915917

Wenger, Markus; Markwalder, Thomas-Marc

2010-01-01

229

Changes in quantitative 3D shape features of the optic nerve head associated with age  

NASA Astrophysics Data System (ADS)

Optic nerve head (ONH) structure is an important biological feature of the eye used by clinicians to diagnose and monitor progression of diseases such as glaucoma. ONH structure is commonly examined using stereo fundus imaging or optical coherence tomography. Stereo fundus imaging provides stereo views of the ONH that retain 3D information useful for characterizing structure. In order to quantify 3D ONH structure, we applied a stereo correspondence algorithm to a set of stereo fundus images. Using these quantitative 3D ONH structure measurements, eigen structures were derived using principal component analysis from stereo images of 565 subjects from the Ocular Hypertension Treatment Study (OHTS). To evaluate the usefulness of the eigen structures, we explored associations with the demographic variables age, gender, and race. Using regression analysis, the eigen structures were found to have significant (p < 0.05) associations with both age and race after Bonferroni correction. In addition, classifiers were constructed to predict the demographic variables based solely on the eigen structures. These classifiers achieved an area under receiver operating characteristic curve of 0.62 in predicting a binary age variable, 0.52 in predicting gender, and 0.67 in predicting race. The use of objective, quantitative features or eigen structures can reveal hidden relationships between ONH structure and demographics. The use of these features could similarly allow specific aspects of ONH structure to be isolated and associated with the diagnosis of glaucoma, disease progression and outcomes, and genetic factors.

Christopher, Mark; Tang, Li; Fingert, John H.; Scheetz, Todd E.; Abramoff, Michael D.

2013-02-01

230

Changes in angle of optic nerve and angle of ocular orbit with increasing age in Japanese children  

PubMed Central

Purpose To study changes in the opening angle of the optic nerve and the angle of the ocular orbit with increasing age in normal Japanese children. Methods We studied 147 normal children (aged 6?months to 18?years) who had undergone CT as a diagnostic procedure. Measurements were performed on axial CT images that included the entire optic nerve of both eyes. The opening angle of the optic nerve was defined as the angle formed by the intersection of a line running through the left optic nerve and a vertical line passing through the centre of the nose. The opening angle of the orbit was defined as the angle formed by the intersection of a line running tangentially along the deep lateral wall of the left orbit and a vertical line passing through the centre of the nose. The relationship between age and these opening angles was analysed by regression analysis. Results The correlation between age and opening angle of the optic nerve was not significant. In contrast, the opening angle of the orbit decreased relatively rapidly until about 2–3?years of age, and then it stabilised. The decrease in the opening angle of the orbit with increasing age was significant (p<0.001). The relationship between these two parameters was best fitted by a logarithmic regression curve. Conclusions Because the opening angle of the orbit decreased significantly with increasing age, this factor must be considered when diagnosing and treating strabismus in children. PMID:25147368

Tsukitome, Hideyuki; Hatsukawa, Yoshikazu; Morimitsu, Tomoko; Yagasaki, Teiji; Kondo, Mineo

2015-01-01

231

TMT-AGE: wide field of regard multi-object adaptive optics for TMT  

NASA Astrophysics Data System (ADS)

We are conducting a feasibility study on a wide field of regard Multi-Object Adaptive Optics system for TMT (TMT-AGE:TMT-Analyzer for Galaxies in the Early universe). The wide FoR is crucial to effectively observe very high-redshift UV-bright galaxies at z>5, which have low surface number density. Simulations of an MOAO system show moderate AO correction can be achieved within 10 arcmin diameter FoR. We discuss overall system design of the wide FoR MOAO system considering the system constraint from the stroke of small-size deformable mirror.

Akiyama, Masayuki; Oya, S.; Ono, Y. H.; TMT-AGE Team

2014-07-01

232

UV emission from young and middle-aged pulsars: Connecting X-rays with the optical  

E-print Network

We present the UV spectroscopy and timing of three nearby pulsars (Vela, B0656+14 and Geminga) recently observed with the Space Telescope Imaging Spectrograph. We also review the optical and X-ray properties of these pulsars and establish their connection with the UV properties. We show that the multiwavelengths properties of neutron stars (NSs) vary significantly within the sample of middle-aged pulsars. Even larger differences are found between the thermal components of Ge-minga and B0656+14 as compared to those of radio-quiet isolated NSs. These differences could be attributed to different properties of the NS surface layers.

O. Kargaltsev; G. G. Pavlov

2006-09-25

233

Optically stimulated luminescence dating of sand-dune formed within the Little Ice Age  

NASA Astrophysics Data System (ADS)

Optically Stimulated Luminescence (OSL) dating has been intensively used to date the late Quaternary deposits. The Single-Aliquot Regenerative-dose (SAR) protocol was applied to measure coarse quartz grains extracted from Dali sand dunes, central China. It was found that this popular method could not accurately date sand dunes activities that recently happened. This is due to the low OSL sensitivity of quartz grains, leading to a failure in OSL dating that has also been met in other sediments before. To overcome this limitation, quartz grains were heated to 500 °C to increase the OSL output for one magnitude. Sensitivity changes could also be corrected by the following test dose OSL responses and has no influence on OSL ages. Thus it is suggested to carry out the SAR protocol for dim and young quartz OSL samples with additional annealing step (e.g. 500 °C) after the measurements of natural cycle. The resultant OSL ages proved that the last sand-dune activities happened during the Little Ice Age (?400 years ago), which was further supported by independent age control (?1600 AD) from historical documents.

Du, Jin-Hua; Wang, Xu-Long

2014-09-01

234

The origin of thick discs  

NASA Astrophysics Data System (ADS)

Thick discs are defined to be disc-like components with a scale height larger than that of the classical discs. They are ubiquitous (Yoachim & Dalcanton 2006; Comerón et al. 2011a), they are made of mostly old and metal-poor stars and are most easily detected in close to edge-on galaxies. Their origin has been considered mysterious and several formation theories have been proposed: • The thick disc being formed secularly by thin disc stars heated by disc overdensities such as giant molecular clouds or spiral arms (Villumsen 1985, ApJ, 290, 75) and by stars moved outwards from their original orbits by radial migration mechanisms (Schönrich & Binney 2009). • The thick disc being formed by the heating of the thin disc by satellites (Quinn et al. 1993) and the tidal stripping of them (Abadi et al. 2003). • The thick disc being formed fast and already thick at high redshift in an highly unstable disc. Inside that thick disc, a thin disc would form afterwards as suggested by Elemgreen & Elmegreen (2006). • The thick disc being formed originally thick at high redshift by the merger of gas-rich protogalactic fragments and a thin disc forming afterwards within it (Brook et al. 2007). The first mechanism is a secular evolution mechanism. The time-scale of the second one is dependent on the merger history of the main galaxy. In the two last mechanisms, the thick disc forms already thick in a short time-scale at high redshift. Recent Milky Way studies, (see, e.g., Bovy et al. 2012), have shown indications that there is no discontinuity between the thin and the thick disc chemical and kinematic properties. Instead, those studies indicate the presence of a monotonic distribution of disc thicknesses. This would suggest a secular origin for the Milky Way thick disc. Studies in external galaxies (Yoachim & Dalcanton 2006; Comerón et al. 2011b), have shown that low-mass disc galaxies have thick disc relative masses much larger than those found in large-mass galaxies. Because low-mass galaxies are dynamically younger than their larger counterparts, it seems difficult for their thick discs to have a secular evolution origin, but simulations show that their thick disc masses are compatible with those of a thick disc formed at high redshift. Thus, recent studies seem to indicate that large-mass galaxies have their thick discs formed mainly due to secular evolution and that low-mass galaxies have them formed at high redshift.

Comerón, Sébastien

2015-03-01

235

Total Disc Arthroplasty for Treating Lumbar Degenerative Disc Disease  

PubMed Central

Study Design Lumber disc arthroplasty is a technological advancement that has occurred in the last decade to treat lumbar degenerative disk diseases. Purpose The aim of this retrospective study was to establish the impact and outcomes of managing patients with lumbar degenerative disk disease who have been treated with lumbar total disc arthroplasty (TDA). Overview of Literature Several studies have shown promising results following this surgery. Methods We reviewed the files of 104 patients at the Department of Neurosurgery in Colmar (France) who had been operated on by lumbar spine arthroplasty (Prodisc) between April 2002 and October 2008. Results Among the 104 patients, 67 were female and 37 were male with an average age of 33.1 years. We followed the cases for a mean of 20 months. The most frequent level of discopathy was L4-L5 with 62 patients (59.6%) followed by L5-S1 level with 52 patients (50%). Eighty-three patients suffered from low back pain, 21 of which were associated with radiculopathy. The status of 82 patients improved after surgery according to the Oswestry Disability Index score, and 92 patients returned to work. Conclusions The results indicate that TDA is a good alternative treatment for lumbar spine disk disease, particularly for patients with disabling and chronic low back pain. This technique contributes to improve living conditions with correct patient selection for surgery. PMID:25705336

2015-01-01

236

Hybrid equalized partial response path-feedback maximum likelihood toward higher density Blu-ray disc  

Microsoft Academic Search

Recently, high density optical recording systems like BD (Blu-ray disc) have been standardized regarding a PRML (partial response maximum likelihood) signal processing technology, which has been thoroughly investigated on high density magnetic recording channels for many years. In order to gain a margin of optical disc drives, PFML (path-feedback maximum likelihood), which is also known as adaptive Viterbi, has been

Satoru Higashino; Yoshiyuki Kajiwara; Kohji Fujimiya; Junya Shiraishi; Tamotsu Yamagami

2005-01-01

237

Probing the Galactic Bulge with deep Adaptive Optics imaging: the age of NGC 6440  

E-print Network

We present first results of a pilot project aimed at exploiting the potentiality of ground based adaptive optics imaging in the near infrared to determine the age of stellar clusters in the Galactic Bulge. We have used a combination of high resolution adaptive optics (ESO-VLT NAOS-CONICA) and wide-field (ESO-NTT-SOFI) photometry of the metal rich globular cluster NGC 6440 located towards the inner Bulge, to compute a deep color magnitude diagram from the tip of the Red Giant Branch down to J~22$, two magnitudes below the Main Sequence Turn Off (TO). The magnitude difference between the TO level and the red Horizontal Branch has been used as an age indicator. It is the first time that such a measurement for a bulge globular cluster has been obtained with a ground based telescope. From a direct comparison with 47 Tuc and with a set of theoretical isochrones, we concluded that NGC 6440 is old and likely coeval to 47 Tuc. This result adds a new evidence that the Galactic Bulge is ~2 Gyr younger at most than the pristine, metal poor population of the Galactic Halo.

L. Origlia; S. Lena; E. Diolaiti; F. R. Ferraro; E. Valenti; S. Fabbri; G. Beccari

2008-09-23

238

On the possibility of a warped disc origin of the inclined stellar discs at the Galactic Centre  

NASA Astrophysics Data System (ADS)

The central parsec of our Galaxy hosts a population of young stars. At distances of r ˜ 0.03-0.5 pc, most of these stars seem to form a system of mutually inclined discs of clockwise and counterclockwise rotating stars. We present a possible warped disc origin scenario for these stars assuming that an initially flat accretion disc becomes warped due to a central radiation source via the Pringle instability or due to a spinning black hole via the Bardeen-Petterson effect before it cools, fragments and forms stars. From simple arguments, we show that this is plausible if the star formation efficiency is high, ?SF ? 1, and the viscosity parameter ? ˜ 0.1. After fragmentation, we model the disc as a collection of concentric, circular rings tilted with respect to each other, and construct time evolution models of warped discs for mass ratios and other parameters relevant to the Galactic Centre environment, but also for more massive discs. We take into account the disc's self-gravity in the non-linear regime and the torques exerted by a slightly flattened surrounding star cluster. Our simulations show that a self-gravitating low-mass disc (Md/Mbh ˜ 0.001) precesses with its integrity maintained in the lifetime of the stars, but precesses essentially freely when the torques from a non-spherical cluster are included. An intermediate-mass disc (Md/Mbh ˜ 0.01) breaks into pieces, which precess as independent discs in the self-gravity-only case, and become disrupted in the presence of the star cluster torques. Finally, for a high-mass disc (Md/Mbh ˜ 0.1), the evolution is dominated by self-gravity and the disc is broken but not dissolved. The time-scale after which the disc breaks into pieces scales almost linearly with Md/Mbh for self-gravitating models. Typical values are longer than the age of the stars for Md/Mbh ˜ 0.001, and are in the range ˜8 × 104-105 yr for Md/Mbh ˜ 0.1-0.01, respectively. None of these discs explains the two Galactic Centre discs with their rotation properties. A comparison of the models with the better defined clockwise rotating disc shows that the lowest mass model in a spherical star cluster matches the data best.

Ulubay-Siddiki, A.; Bartko, H.; Gerhard, O.

2013-01-01

239

Optical absorption as a sensitive monitor of tensile strength loss in thermally aged nylon 6,6  

SciTech Connect

Chemical changes which take place in polymers during thermal aging often adversely affect the bulk physical properties of the material. Aging rates under ambient conditions are usually so slow as to require extremely long aging cycles to achieve measurable losses in such properties as tensile strength. Therefore, accelerated aging under more stressful conditions (e.g., higher temperatures) with Arrhenius-plot extrapolations to ambient conditions is often employed. Since this scheme requires that there is no change in the predominate aging mechanism at higher temperatures, one would prefer to increase the sensitivity of aging detection so one could measure aging at lower temperatures on a reasonable time scale. We describe here the use of optical absorption spectrophotometry as a sensitive monitor of thermal aging in nylon 6,6 which correlates with tensile strength loss. 8 refs., 3 figs.

Renschler, C.L.

1985-01-01

240

Role of load history in intervertebral disc mechanics and intradiscal pressure generation.  

PubMed

Solid-fluid interactions play an important role in mediating viscoelastic behaviour of biological tissues. In the intervertebral disc, water content is governed by a number of factors, including age, disease and mechanical loads, leading to changes in stiffness characteristics. We hypothesized that zonal stress distributions depend on load history, or the prior stresses experienced by the disc. To investigate these effects, rat caudal motion segments were subjected to compressive creep biomechanical testing in vitro using a protocol that consisted of two phases: a Prestress Phase (varied to represent different histories of load) followed immediately by an Exertion Phase, identical across all Prestress groups. Three analytical models were used to fit the experimental data in order to evaluate load history effects on gross and zonal disc mechanics. Model results indicated that while gross transient response was insensitive to load history, there may be changes in the internal mechanics of the disc. In particular, a fluid transport model suggested that the role of the nucleus pulposus in resisting creep during Exertion depended on Prestress conditions. Separate experiments using similarly defined load history regimens were performed to verify these predictions by measuring intradiscal pressure with a fibre optic sensor. We found that the ability for intradiscal pressure generation was load history-dependent and exhibited even greater sensitivity than predicted by analytical models. A 0.5 MPa Exertion load resulted in 537.2 kPa IDP for low magnitude Prestress compared with 373.7 kPa for high magnitude Prestress. Based on these measurements, we developed a simple model that may describe the pressure-shear environment in the nucleus pulposus. These findings may have important implications on our understanding of how mechanical stress contributes to disc health and disease etiology. PMID:21380846

Hwang, David; Gabai, Adam S; Yu, Miao; Yew, Alvin G; Hsieh, Adam H

2012-01-01

241

Neurovascular coupling in normal aging: A combined optical, ERP and fMRI study  

PubMed Central

Brain aging is characterized by changes in both hemodynamic and neuronal responses, which may be influenced by the cardiorespiratory fitness of the individual. To investigate the relationship between neuronal and hemodynamic changes, we studied the brain activity elicited by visual stimulation (checkerboard reversals at different frequencies) in younger adults and in older adults varying in physical fitness. Four functional brain measures were used to compare neuronal and hemodynamic responses obtained from BA17: two reflecting neuronal activity (the event-related optical signal, EROS, and the C1 response of the ERP), and two reflecting functional hemodynamic changes (functional magnetic resonance imaging, fMRI, and near-infrared spectroscopy, NIRS). The results indicated that both younger and older adults exhibited a quadratic relationship between neuronal and hemodynamic effects, with reduced increases of the hemodynamic response at high levels of neuronal activity. Although older adults showed reduced activation, similar neurovascular coupling functions were observed in the two age groups when fMRI and deoxy-hemoglobin measures were used. However, the coupling between oxy-and deoxy-hemoglobin changes decreased with age and increased with increasing fitness. These data indicate that departures from linearity in neurovascular coupling may be present when using hemodynamic measures to study neuronal function. PMID:23664952

Fabiani, Monica; Gordon, Brian A.; Maclin, Edward L.; Pearson, Melanie A.; Brumback-Peltz, Carrie R.; Low, Kathy A.; McAuley, Edward; Sutton, Bradley P.; Kramer, Arthur F.; Gratton, Gabriele

2013-01-01

242

Rewritable dual-layer blu-ray disc media  

Microsoft Academic Search

The Blu-ray Disc (BD) optical recording system utilizes a blue laser (405 nm wavelength) in combination with a high-numerical-aperture (NA = 0.85) objective lens. This BD-format allows storing 23 - 27 GB on a single-layer and 46 - 54 GB on a dual-layer 12 cm disc at 36 Mbps user data rate. This paper reports on the design, manufacturing, and

Andrei V. Mijiritskii; Jochen Hellmig; Herman J. Borg; Piet H. Vromans; Katerina Musialkova; Jos A. Van Haaren

2003-01-01

243

Effect of sol-age on the surface and optical properties of sol-gel derived mesoporous zirconia thin films  

NASA Astrophysics Data System (ADS)

Mesoporous ZrO2 thin films have been deposited by a modified sol-gel dip coating technique using HCl as catalyst. Effects of sol-age on the surface and on the optical properties are studied. Transmission electron micrographs of the films reveal the pore dimensions in mesoporous regime. A strong correlation in surface topography with sol-age has been observed where increase in sol-age induces a systematic enhancement in the value of root mean square roughness of the films. Optical study shows that deposited films have high transmittance and an enhancement of 5.6 times in porosity in films prepared with sol-age of 10 days with respect to that of 1 day. Band gap estimation by Tauc's plots of films is observed to 5.74 eV, which shows invariance with the sol-age.

Kumar, Manish; Reddy, G. B.

2011-06-01

244

Revival of the Jumping Disc  

ERIC Educational Resources Information Center

Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

Ucke, C.; Schlichting, H-J.

2009-01-01

245

The DISC Quotient  

NASA Astrophysics Data System (ADS)

D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

Elliott, John R.; Baxter, Stephen

2012-09-01

246

Rotating disc viscometer  

Microsoft Academic Search

A rotating disc viscometer, capable of performing accurate measurements in the critical region of a fluid, is described. The apparatus, developed in the authors' laboratory, allows viscosity measurements to be performed with a very small fluid sample at the desired shear rate.

L. Bruschi; M. Santini; G. Torzo

1984-01-01

247

Modeling the Compact Disc Read System in Lab  

ERIC Educational Resources Information Center

One of the great, engaging aspects of physics is its application to everyday technology. The compact disc player is an example of one such technology that applies fundamental principles from optics in order to efficiently store and quickly retrieve information. We have created a lab in which students use simple optical components to assemble a…

Hinaus, Brad; Veum, Mick

2009-01-01

248

Psychometric Attributes of the DISC Predictive Scales  

PubMed Central

Introduction: This study was designed to evaluate the psychometric attributes and screening efficiency of a Spanish version of the Children Predictive Scales (DPS) against the Spanish Diagnostic Interview Schedule for Children (DISC-IV). Method: This pilot cross-sectional study included 61 children aged 9 to 14 years in a mainstream school. The following psychometric attributes were analyzed: acceptability, scale assumptions, internal consistency, and precision, as well the predictive validity (AUC). Results: The scale did not show ceiling or floor effects (6.4%, 1.3%, respectively). The internal consistency was high (?=0.92), and the standard error of measurement was adequate (SEM=1.54). The overall DPS AUC was 0.72 against DISC IV corresponding diagnosis. Conclusion: The Spanish version of the DPS-4.32 seems to be a reliable and precise tool for screening mental health disorders in a school-age population. PMID:21139991

Cubo, Esther; Velasco, Sara Sáez; Benito, Vanesa Delgado; Villaverde, Vanesa Ausín; Galín, José María Trejo Gabriel; Santidrián, Asunción Martín; Vicente, Jesús Macarrón; Guevara, José Cordero; Louis, Elan D; Benito-León, Julián

2010-01-01

249

Optical-UV Spectrum of the Middle-aged Pulsar B1055-52  

NASA Astrophysics Data System (ADS)

The middle-aged radio, X-ray and gamma-ray pulsar B1055-52 is one of the few pulsars that allow a multiwavelength study of pulsar radiation. An optical counterpart of the pulsar has been detected with the HST FOC, but it was observed in only one filter {F342W, m=24.9}. To understand the nature of the pulsar radiation, its spectrum must be measured in a broad wavelegth range. We propose imaging observations of the pulsar's counterpart with WFPC2 in the red part of the spectrum and ACS/SBC in the UV part to measure the broadband spectral distribution, compare it with the X-ray spectrum, and investigate the thermal and magnetospheric components of the pulsar's radiation.

Pavlov, George

2007-07-01

250

Gas modelling in the disc of HD 163296  

NASA Astrophysics Data System (ADS)

We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ~4 Myr, with evidence of a circumstellar disc extending out to ~540 AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (GAS in Protoplanetary Systems), consisting of a detection of the [Oi] 63 ?m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the 12CO 3-2, 2-1 and 13CO J = 1-0 line transitions, as well as an upper limit for the H2 0-0 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry.

Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W.-F.; Isella, A.; Roberge, A.; Martin-Zaidi, C.; Kamp, I.; Pinte, C.; Sandell, G.; Vacca, W. D.; Ménard, F.; Mendigutía, I.; Duchêne, G.; Dent, W. R. F.; Aresu, G.; Meijerink, R.; Spaans, M.

2012-02-01

251

Gas Modelling in the Disc of HD 163296  

NASA Technical Reports Server (NTRS)

We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of approx. 4Myr, with evidence of a circumstellar disc extending out to approx. 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [Oi] 63 m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the CO-12 3-2, 2-1 and CO-13 J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry

Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W. -F.; Isella, A.; Roberge, A.; Martin-Zaidi, C.; Kamp, I.; Pinte, C.; Sandell, G.; Vacca, W. D.; Menard, F.; Mendigutia, I.; Duchene, G.; Dent, W. R. F.; Aresu, G.; Meijerink, R.; Spaans, M.

2011-01-01

252

Mechanotransduction in intervertebral discs  

PubMed Central

Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492

Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang

2014-01-01

253

Biomechanics of Disc Degeneration  

PubMed Central

Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the “gold standard” in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914

Palepu, V.; Kodigudla, M.; Goel, V. K.

2012-01-01

254

[Cervical disc herniation].  

PubMed

The cervical disc herniation is characterized by prolapsed nucleus pulposus material through the annulus into the spinal canal. The local mechanical or chemical irritation of neural structures typically leads to symptoms of radiculopathy, cervicocephalgia or myelopathy. Pronounced sensorimotor deficits or intractable pain constitute surgical treatment. In all other cases conservative treatment is indicated, including pain medication, active and passive physiotherapy, and local injections, respectively. Anterior cervical discectomy and interbody fusion (ACDF) is still the surgical treatment of choice. Predominantly, cages with or without plates are in use to obtain solid fusion. The implantation of a total disc replacement is a viable alternative, if no contraindications exist. Other surgical techniques may be performed in proper selected cases. The overall clinical and radiological results of both surgical and conservative treatment are good. PMID:23296562

Schnake, K J; Hoffmann, C-H; Kandziora, F

2012-12-01

255

Vortices in Astrophysical Discs  

NASA Astrophysics Data System (ADS)

Dynamical theory of astrophysical discs predicts two different kinds of vortices: ``linear'' and ``nonlinear.'' If galactic spiral arms are density waves, linear vortices in the velocity field are predicted at infinitesimal amplitude, and both spirals and vortices grow together at equal rate. The centres of linear vortices lie in the neighborhood of the corotation circle and between spiral arms for both spiral generation mechanisms considered here. Linear vortices (anticyclones), which were predicted on the basis of experiments with rotating shallow water, have been observed in spiral galaxies both when the rotation curve has a velocity jump and when it is smooth. There are at least two kinds of nonlinear vortices which occur at a finite amplitude only: Rossby vortices and nonlinear convection. Rossby vortices are described by a 2-D equation, derived from the 3-D nonlinear hydrodynamical equations, which has both scalar and vector nonlinearities. Rossby vortices are independent of the presence of spiral waves and consist of two kinds: single solitary vortices (cyclones and anticyclones) and double solitary vortices (modons). Nonlinear convection is described by the time-averaged nonlinear 3-D hydrodynamical equations taking into account the vertical structure of the disc. It is caused by nonlinear Reynolds stresses induced by the spiral density wave and has a form of four, large-scale, toroidal vortices separated by the vertical cylindrical surface at corotation and the central plane of the disc.

Fridman, A. M.; Khoruzhii, O. V.

1999-04-01

256

Lumbar disc replacement: update.  

PubMed

Over the last decades, fusion of lumbar spinal motion segments has represented the mainstay of treatment of lumbar degenerative conditions which failed to respond adequately to conservative therapy. Increasing demands and expectations from patients as well as the necessity to avoid fusion related negative side effects such as adjacent level disc degeneration, considerable complication and reoperation rates, cranial facet joint violations, pseudarthrosis and others led to the development of motion preserving technologies such as total lumbar disc replacement (TDR). The first and rudimentary attempts to preserve motion of lumbar motion segments can be dated back to the early 1950s. Over the past two to three decades, a variety of new implants with different motion characteristics have been developed and introduced into the market. Despite of the extensive knowledge which has been gained in this field of research, insurers in the United States have refused to reimburse surgeons due to fear of late complications and reoperations as well as unknown secondary costs, which led to a global decline in the numbers of TDR procedures. The current literature review intends to provide a concise summary of the adequate indications for TDR as well as outcome determining factors and delineate the role of TDR in the currently available armamentarium for the treatment of low back pain (LBP) resulting from degenerative disc disease (DDD) without instabilities or deformities. PMID:25649068

Heider, F C; Mayer, H M; Siepe, C J

2015-06-01

257

Ischemic optic neuropathy  

Microsoft Academic Search

Ischemic optic neuropathy (ION), based on vascular anatomy of the optic nerve, pathogenesis and clinical picture, consists of two distinct entities: anterior (AION) and posterior (PION) ischemic optic neuropathies. AION is due to interference with posterior ciliary artery supply to the optic nerve head and retrolaminar part of the optic nerve; it initially presents with visual loss and optic disc

Sohan Singh Hayreh

1978-01-01

258

Disc resonator gyroscope fabrication process requiring no bonding alignment  

NASA Technical Reports Server (NTRS)

A method of fabricating a resonant vibratory sensor, such as a disc resonator gyro. A silicon baseplate wafer for a disc resonator gyro is provided with one or more locating marks. The disc resonator gyro is fabricated by bonding a blank resonator wafer, such as an SOI wafer, to the fabricated baseplate, and fabricating the resonator structure according to a pattern based at least in part upon the location of the at least one locating mark of the fabricated baseplate. MEMS-based processing is used for the fabrication processing. In some embodiments, the locating mark is visualized using optical and/or infrared viewing methods. A disc resonator gyroscope manufactured according to these methods is described.

Shcheglov, Kirill V. (Inventor)

2010-01-01

259

First results of the SONS survey: submillimetre detections of debris discs  

NASA Astrophysics Data System (ADS)

New detections of debris discs at submillimetre wavelengths present highly valuable complementary information to prior observations of these sources at shorter wavelengths. Characterization of discs through spectral energy distribution modelling including the submillimetre fluxes is essential for our basic understanding of disc mass and temperature, and presents a starting point for further studies using millimetre interferometric observations. In the framework of the ongoing SCUBA-2 Observations of Nearby Stars, the instrument SCUBA-2 on the James Clerk Maxwell Telescope was used to provide measurements of 450 and 850 ?m fluxes towards a large sample of nearby main-sequence stars with debris discs detected previously at shorter wavelengths. We present the first results from the ongoing survey, concerning 850 ?m detections and 450 ?m upper limits towards 10 stars, the majority of which are detected at submillimetre wavelengths for the first time. One, or possibly two, of these new detections is likely a background source. We fit the spectral energy distributions of the star+disc systems with a blackbody emission approach and derive characteristic disc temperatures. We use these temperatures to convert the observed fluxes to disc masses. We obtain a range of disc masses from 0.001 to 0.1 M?, values similar to the prior dust mass measurements towards debris discs. There is no evidence for evolution in dust mass with age on the main sequence, and indeed the upper envelope remains relatively flat at ?0.5 M? at all ages. The inferred disc masses are lower than those from disc detections around pre-main-sequence stars, which may indicate a depletion of solid mass. This may also be due to a change in disc opacity, though limited sensitivity means that it is not yet known what fraction of pre-main-sequence stars have discs with dust masses similar to debris disc levels. New, high-sensitivity detections are a path towards investigating the trends in dust mass evolution.

Pani?, O.; Holland, W. S.; Wyatt, M. C.; Kennedy, G. M.; Matthews, B. C.; Lestrade, J. F.; Sibthorpe, B.; Greaves, J. S.; Marshall, J. P.; Phillips, N. M.; Tottle, J.

2013-10-01

260

Pushing the limits of optical storage  

Microsoft Academic Search

Philips Research has been working on improvements of optical disc storage technology for three decades. In this period, optical discs have become the technology of choice for storing and sharing of data on removable media. In 30 years we have made an improvement of about 2 orders of magnitude in both data rate and storage density. The new Blu-ray Disc

J. A. M. M. van Haaren

2005-01-01

261

Change in the optical properties of ski-3 rubber in deformation, fatigue, and thermal and radiation aging  

Microsoft Academic Search

Optical methods can be used in studying the kinetics of mechanical fatigue, thermal, and radiation aging; some general characteristics and differences in the development of these processes in elastomers with higher extinction can be detected with them. The sensitivity of the measurements is increased by the rational selection of the light wave-length of preliminary homogeneous biaxial stretching. A decrease in

S. K. Meshchaninov; V. I. Dyrda; V. M. Parfeev

1991-01-01

262

Enclosed rotary disc air pulser  

DOEpatents

An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

Olson, A. L. (Idaho Falls, ID); Batcheller, Tom A. (Idaho Falls, ID); Rindfleisch, J. A. (Arco, ID); Morgan, John M. (Arco, ID)

1989-01-01

263

Initial conditions for disc galaxies  

E-print Network

We present a general recipe for constructing N-body realizations of galaxies comprised of near-spherical and disc components. First, an exact spherical distribution function for the spheroids (halo & bulge) is determined, such that it is in equilibrium with the gravitational monopole of the disc components. Second, an N-body realisation of this model is adapted to the full disc potential by growing the latter adiabatically from its monopole. Finally, the disc is sampled with particles drawn from an appropriate distribution function, avoiding local-Maxwellian approximations. We performed test simulations and find that the halo and bulge radial density profile very closely match their target model, while they become slightly oblate due to the added disc gravity. Our findings suggest that vertical thickening of the initially thin disc is caused predominantly by spiral and bar instabilities, which also result in a radial re-distribution of matter, rather than scattering off interloping massive halo particles.

Paul J. McMillan; Walter Dehnen

2007-04-30

264

Inflammation in intervertebral disc degeneration and regeneration  

PubMed Central

Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players. PMID:25673296

Molinos, Maria; Almeida, Catarina R.; Caldeira, Joana; Cunha, Carla; Gonçalves, Raquel M.; Barbosa, Mário A.

2015-01-01

265

Inflammation in intervertebral disc degeneration and regeneration.  

PubMed

Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players. PMID:25673296

Molinos, Maria; Almeida, Catarina R; Caldeira, Joana; Cunha, Carla; Gonçalves, Raquel M; Barbosa, Mário A

2015-03-01

266

Numbered nasal discs for waterfowl  

USGS Publications Warehouse

Numbered nasal discs were successfully used in studies requiring large numbers of individually marked waterfowl. The procedure for constructing these discs is outlined. Blue-winged teal (Anas discors) with 5/8-inch discs, and canvasback (Aythya valisineria) and redhead (A. americana) with 3/4-inch discs can be individually identified up to 50 and 80 yards, respectively, with a gunstock-mounted, 20-power spotting scope. The particular value of these markers is their durability, the number of combinations possible, and the apparent absence of behavioral or mortality influence among such species as the blue-winged teal.

Bartonek, J.C.; Dane, C.W.

1964-01-01

267

The Combined Use of a Posterior Dynamic Transpedicular Stabilization System and a Prosthetic Disc Nucleus Device in Treating Lumbar Degenerative Disc Disease With Disc Herniations  

PubMed Central

Background Prosthetic replacement of spinal discs is emerging as a treatment option for degenerative disc disease. Posterior dynamic transpedicular stabilization (PDTS) and prosthetic disc nucleus (PDN) devices have been used sporadically in spinal surgery. Methods This was a prospective study of 13 patients averaging 40.9 years of age with degenerative disc disease who underwent posterior placement of a PDN with a PDTS. The Oswestry low-back pain disability questionnaire and visual analog scale (VAS) for pain were used to assess patient outcomes at the 3rd, 6th, and 12th postoperative months. Lumbar range of motion was evaluated using a bubble inclinometer preoperatively and at 12 months postoperatively. Radiological parameters including lumbar lordosis angle (LL), segmental lordosis angle (?), disc height at the operated level (DHo), and disc height of the adjacent level (DHu) were evaluated. A typical midline posterior approach for complete discectomy was followed by the simultaneous placement of the PDN with PDTS. Results Both the Oswestry and VAS scores showed significant improvement postoperatively (P < .05). There were no significant differences in LL, ?, DHo, and DHu parameters. We observed complications in 3 patients including 2 patients who had the PDN device embedded into the adjacent corpus; 1 had massive endplate degeneration, and the other experienced interbody space infection. In 1 patient, the PDN device migrated to one side in the vertebral space. Conclusion The use of a PDN in combination with posterior dynamic instrumentation can help to restore the physiologic motion of the anterior and posterior column and could help to establish posterior dynamic instrumentation as an important treatment of degenerative disc disease. Theoretically this concept is superior, but practically we need more advanced technology to replace disc material. Because this study examined the combination of the PDN and stabilization instrumention, the results cannot be compared with those reported in the literature for either PDN alone or dynamic screws alone. Level of Evidence Prospective cohort study with good follow-up (level 1b).

Aydin, Ahmet Levent; Oktenoglu, Tunc; Cosar, Murat; Ataker, Yaprak; Kaner, Tuncay; Ozer, Ali Fahir

2008-01-01

268

An overview of the Blu-ray disc application format for HD-movie distribution  

Microsoft Academic Search

Blu-ray Disc (BD) is the next generation optical disc format, currently being standardized by a large consortium of leading CE, PC, authoring companies and major movie studios. BD offers more than five times the capacity of DVD at 25 GB and 50 GB (dual layer). The BD application format addresses the limitations of DVD-Video by providing a complete user experience.

Young Peng; Michelle Wang; Declan Kelly; Wouter Leibbrandt

2005-01-01

269

Vertical cup-to-disc ratio measurement for diagnosis of glaucoma on fundus images  

NASA Astrophysics Data System (ADS)

Glaucoma is a leading cause of permanent blindness. Retinal fundus image examination is useful for early detection of glaucoma. In order to evaluate the presence of glaucoma, the ophthalmologists determine the cup and disc areas and they diagnose glaucoma using a vertical cup-to-disc ratio. However, determination of the cup area is very difficult, thus we propose a method to measure the cup-to-disc ratio using a vertical profile on the optic disc. First, the blood vessels were erased from the image and then the edge of optic disc was then detected by use of a canny edge detection filter. Twenty profiles were then obtained around the center of the optic disc in the vertical direction on blue channel of the color image, and the profile was smoothed by averaging these profiles. After that, the edge of the cup area on the vertical profile was determined by thresholding technique. Lastly, the vertical cup-to-disc ratio was calculated. Using seventy nine images, including twenty five glaucoma images, the sensitivity of 80% and a specificity of 85% were achieved with this method. These results indicated that this method can be useful for the analysis of the optic disc in glaucoma examinations.

Hatanaka, Yuji; Noudo, Atsushi; Muramatsu, Chisako; Sawada, Akira; Hara, Takeshi; Yamamoto, Tetsuya; Fujita, Hiroshi

2010-03-01

270

TMT-AGE: wide field of regard multi-object adaptive optics for TMT  

NASA Astrophysics Data System (ADS)

We introduce current status of the feasibility study on a wide field of regard (FoR) Multi-Object Adaptive Optics (MOAO) system for TMT (TMT-AGE: TMT-Analyzer for Galaxies in the Early universe). MOAO is a system which realize high spatial-resolution observations of multiple objects scattered in a wide FoR. In this study, we put emphasise on the FoR as wide as 10' diameter. The wide FoR is crucial to effectively observe very high-redshift galaxies, which have low surface number density. Simulations of an MOAO system with 8 LGSs show close-to-diffraction-limited correction can be achieved within 5' diameter FoR and moderate AO correction can be achieved within 10' diameter FoR. We discuss overall system design of the wide FoR MOAO system considering the constraint from the stroke of small-size deformable mirror (DM). We also introduce current status of developments of key components of an MOAO system; high-dynamic range wavefront sensor (WFS) and large-stroke small-size DM, and real time computer (RTC) with fast tomographic reconstruction.

Akiyama, Masayuki; Oya, Shin; Ono, Yoshito H.; Takami, Hideki; Ozaki, Shinobu; Hayano, Yutaka; Iwata, Ikuru; Hane, Kazuhiro; Wu, Tong; Yamamuro, Tomoyasu; Ikeda, Yuji

2014-07-01

271

Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay  

Technology Transfer Automated Retrieval System (TEKTRAN)

Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...

272

Disc Replacement for Low Back Pain  

MedlinePLUS

... Map AAPM&R > Patients & Family > Conditions & Treatments > Musculoskeletal > Spine (Neck and Back) > Disc Replacement for Low Back Pain Disc Replacement for Low Back Pain Page Content The evolution of disc replacement surgery may help select patients ...

273

Galaxy Zoo: CANDELS barred discs and bar fractions  

NASA Astrophysics Data System (ADS)

The formation of bars in disc galaxies is a tracer of the dynamical maturity of the population. Previous studies have found that the incidence of bars in discs decreases from the local Universe to z ˜ 1, and by z > 1 simulations predict that bar features in dynamically mature discs should be extremely rare. Here, we report the discovery of strong barred structures in massive disc galaxies at z ˜ 1.5 in deep rest-frame optical images from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey. From within a sample of 876 disc galaxies identified by visual classification in Galaxy Zoo, we identify 123 barred galaxies. Selecting a subsample within the same region of the evolving galaxy luminosity function (brighter than L*), we find that the bar fraction across the redshift range 0.5 ? z ? 2 ( f_{bar} = 10.7^{+6.3}_{-3.5} per cent after correcting for incompleteness) does not significantly evolve. We discuss the implications of this discovery in the context of existing simulations and our current understanding of the way disc galaxies have evolved over the last 11 billion years.

Simmons, B. D.; Melvin, Thomas; Lintott, Chris; Masters, Karen L.; Willett, Kyle W.; Keel, William C.; Smethurst, R. J.; Cheung, Edmond; Nichol, Robert C.; Schawinski, Kevin; Rutkowski, Michael; Kartaltepe, Jeyhan S.; Bell, Eric F.; Casteels, Kevin R. V.; Conselice, Christopher J.; Almaini, Omar; Ferguson, Henry C.; Fortson, Lucy; Hartley, William; Kocevski, Dale; Koekemoer, Anton M.; McIntosh, Daniel H.; Mortlock, Alice; Newman, Jeffrey A.; Ownsworth, Jamie; Bamford, Steven; Dahlen, Tomas; Faber, Sandra M.; Finkelstein, Steven L.; Fontana, Adriano; Galametz, Audrey; Grogin, N. A.; Grützbauch, Ruth; Guo, Yicheng; Häußler, Boris; Jek, Kian J.; Kaviraj, Sugata; Lucas, Ray A.; Peth, Michael; Salvato, Mara; Wiklind, Tommy; Wuyts, Stijn

2014-12-01

274

Resonances in retrograde circumbinary discs  

NASA Astrophysics Data System (ADS)

We analyse the interaction of an eccentric binary with a circular coplanar circumbinary disc that rotates in a retrograde sense with respect to the binary. In the circular binary case, no Lindblad resonances lie within the disc and no Lindblad resonant torques are produced, as was previously known. By analytic means, we show that when the binary orbit is eccentric, there exist components of the gravitational potential of the binary which rotate in a retrograde sense to the binary orbit and so rotate progradely with respect to this disc, allowing a resonant interaction to occur between the binary and the disc. The resulting resonant torques distinctly alter the disc response from the circular binary case. We describe results of three-dimensional hydrodynamic simulations to explore this effect and categorize the response of the disc in terms of modes whose strengths vary as a function of binary mass ratio and eccentricity. These mode strengths are weak compared to the largest mode strengths expected in the prograde case where the binary and disc rotate in the same sense. However, for sufficiently high binary eccentricity, resonant torques open a gap in a retrograde circumbinary disc, while permitting gas inflow on to the binary via gas streams. The inflow results in a time varying accretion rate on to the binary that is modulated over the binary orbital period, as was previously found to occur in the prograde case.

Nixon, Chris; Lubow, Stephen H.

2015-04-01

275

Forming disc galaxies in ?CDM simulations  

NASA Astrophysics Data System (ADS)

We used fully cosmological, high-resolution N-body + smooth particle hydrodynamic (SPH) simulations to follow the formation of disc galaxies with rotational velocities between 135 and 270kms-1 in a ? cold dark matter (CDM) universe. The simulations include gas cooling, star formation, the effects of a uniform ultraviolet (UV) background and a physically motivated description of feedback from supernovae (SNe). The host dark matter haloes have a spin and last major merger redshift typical of galaxy-sized haloes as measured in recent large-scale N-body simulations. The simulated galaxies form rotationally supported discs with realistic exponential scalelengths and fall on both the I band and baryonic Tully-Fisher relations. An extended stellar disc forms inside the Milky Way (MW)-sized halo immediately after the last major merger. The combination of UV background and SN feedback drastically reduces the number of visible satellites orbiting inside a MW-sized halo, bringing it in fair agreement with observations. Our simulations predict that the average age of a primary galaxy's stellar population decreases with mass, because feedback delays star formation in less massive galaxies. Galaxies have stellar masses and current star formation rates as a function of total mass that are in good agreement with observational data. We discuss how both high mass and force resolution and a realistic description of star formation and feedback are important ingredients to match the observed properties of galaxies.

Governato, F.; Willman, B.; Mayer, L.; Brooks, A.; Stinson, G.; Valenzuela, O.; Wadsley, J.; Quinn, T.

2007-02-01

276

Blu-ray Disc Pickup Head for Dual Layer  

Microsoft Academic Search

For dual-layer Blu-ray disc (BD) recording systems, the compensation of thickness differences is required. In addition the influence from the other layer should be considered. As a spherical compensation method, we have adopted a liquid crystal panel to fabricate a compact pickup head. Furthermore we have inserted a polarization diffractive optical element to reduce the influence from the other layer.

Tae Kyung Kim; Young Man Ahn; Seok Jung Kim; Tae Youn Heor; Chong Sam Chung; In Sik Park

2005-01-01

277

Intelligent Video Disc as a Major Component of Individualized Instruction.  

ERIC Educational Resources Information Center

Due to the importance of visual stimuli for learning, the videodisc is expected to have a major impact on education. When combined with the computer, it will greatly expand the capabilities of computer assisted instruction. There are two major types of videodisc equipment: the optical type with a laser beam to read the information from the disc,…

Ingalls, Richard E.

278

A SCUBA-2 850-?m survey of protoplanetary discs in the ? Orionis cluster  

NASA Astrophysics Data System (ADS)

We present the results from a large 850-?m survey of the ? Orionis cluster using the SCUBA-2 camera on the James Clerk Maxwell Telescope. The 0.5° diameter circular region we surveyed contains 297 young stellar objects with an age estimated at about 3 Myr. We detect nine of these objects, eight of which have infrared excesses from an inner disc. We also serendipitously detect three non-stellar sources at >5? that are likely background submillimetre galaxies. The nine detected stars have inferred disc masses ranging from 5 to about 17 MJup, assuming similar dust properties as Taurus discs and an interstellar medium gas-to-dust ratio of 100. There is a net positive signal towards the positions of the individually undetected infrared excess sources indicating a mean disc mass of 0.5 MJup. Stacking the emission towards those stars without infrared excesses constrains their mean disc mass to less than 0.3 MJup, or an equivalent Earth mass in dust. The submillimetre luminosity distribution is significantly different from that in the younger Taurus region, indicating disc mass evolution as star-forming regions age and the infrared excess fraction decreases. Submillimetre Array observations reveal CO emission towards four sources demonstrating that some, but probably not much, molecular gas remains in these relatively evolved discs. These observations provide new constraints on the dust and gas mass of protoplanetary discs during the giant planet building phase and provide a reference level for future studies of disc evolution.

Williams, Jonathan P.; Cieza, Lucas A.; Andrews, Sean M.; Coulson, Iain M.; Barger, Amy J.; Casey, Caitlin M.; Chen, Chian-Chou; Cowie, Lennox L.; Koss, Michael; Lee, Nicholas; Sanders, David B.

2013-10-01

279

Cervical total disc arthroplasty.  

PubMed

Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer. PMID:24353955

Basho, Rahul; Hood, Kenneth A

2012-06-01

280

Osteopenia and Total Disc Prosthesis Subsidence: Inclusion/Exclusion Criteria for Total Disc Replacement  

PubMed Central

Background Prosthetic subsidence is an adverse event of disc arthroplasty with a total disc prosthesis. Factors affecting prosthetic subsidence are (1) the size of the prosthetic endplate (footprint), (2) amount of load applied to the spine, and (3) compressive strength of the vertebral bone. The size of the prosthetic endplate has been addressed adequately in the development of the current generation of total disc prostheses. However, little information is available on the relation between osteopenia (low bone mineral density [BMD]) and prosthetic subsidence. We evaluated the relation between osteopenia and compressive strength of vertebral bone and propose an inclusion/exclusion guideline for disc arthroplasty in the presence of osteopenia. Methods This study was based on previously published data by C.K. Lee on bone mineral density, contact surface area, and applied load that emphasized the critical contact surface area required to prevent subsidence. The study included 35 cadaveric vertebral bones (representing ages 38–68) that were evaluated via quantitative computed tomography for BMD and subjected to nondestructive and destructive tests for compressive strength of the vertebral bones. The relationship of osteopenia to prosthetic subsidence was evaluated from the data. Results Patients with average BMD (0.137 g/cm3) require a minimum contact surface area of 6.5 cm2 for the physiologic load of 2500 N. Patients with a BMD of up to 1 SD below the average will require 9.1 cm2 of contact area for the same load. Patients with a BMD of up to 2 SD below the average will require 13 cm2 of contact area. Discussion The average endplate surface area of small disc prostheses is about 6.5–8 cm2, which is enough to tolerate normal physiologic load for patients with normal BMD. Patients with BMD of 2 SD below the average will require a disc prosthesis with an endplate surface area greater than 12.75 cm2 to tolerate normal physiologic load. The largest size of prosthetic endplate of the currently available disc prostheses is about 11 cm2; therefore, patients with BMD below 2 SD will have a high risk of subsidence, and these patients should be excluded for disc arthroplasty. Patients with BMD between –1.5 SD and –2.0 SD may be included for disc arthroplasty only when they can receive the large size of prosthesis with greater than 10.5 cm2 prosthetic endplates. Conclusions All patients should be evaluated preoperatively with BMD measurement. Patients with a BMD of up to 1.5 SD below the average can be included for total disc arthroplasty. Patients with BMD of 2 SD below the average should be excluded for total disc arthroplasty, and patients with BMD of 1.5–2 SD below the average should be carefully evaluated for the appropriate size of the prosthesis prior to the surgery.

2007-01-01

281

Clinical Evaluation of Disc Battery Ingestion in Children  

PubMed Central

BACKGROUND The purpose of this study was to evaluate the characteristics, management, and outcomes of disc battery ingestion in children. METHODS We reviewed the medical records of children admitted to Mofid Children’s Hospital due to disc battery ingestion from January 2006 to January 2010. Clear history, clinical symptoms and results of imaging studies revealed diagnosis of disc battery ingestion in suspected patients. The clinical data reviewed included age, gender, clinical manifestation, radiologic findings, location of disc battery, duration of ingestion, endoscopic results and surgical treatment. RESULTS We found 22 cases (11 males and 11 females) of disc battery ingestion with a mean age of 4.3 years (range: 9 months to 12 years). Common symptoms were vomiting, cough, dysphagia, and dyspnea. The mean duration of ingestion was 2.7 days (4 hours to 1.5 months). A total of 19 patients had histories of disc battery ingestion, but three cases referred with the above symptoms, and the batteries were accidentally found by x-ray. Only three cases had batteries impacted in the esophagus. Twelve batteries were removed endoscopically, 6 batteries spontaneously passed through the gastrointestinal (GI) tract within 5 to 7 days, and 4 patients underwent surgery due to complications: 3 due to tracheo-esophageal fistula (TEF) and 1 due to intestinal perforation. There was no mortality in our study. CONCLUSION Most cases of disc battery ingestion run uneventful courses, but some may be complicated. If the battery lodges in the esophagus, emergency endoscopic management is necessary. However, once in the stomach, it will usually pass through the GI tract. PMID:24829643

Mirshemirani, AliReza; Khaleghnejad-tabari, Ahmad; Kouranloo, Jaefar; Sadeghian, Naser; Rouzrokh, Mohsen; Roshanzamir, Fatolah; Razavi, Sajad; Sayary, Ali Akbar; Imanzadeh, Farid

2012-01-01

282

Double-disc gate valve  

DOEpatents

This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

Wheatley, Seth J. (Oak Ridge, TN)

1979-01-01

283

Magnetic resonance characteristics of temporomandibular joint disc displacement in elderly patients  

PubMed Central

Objectives The purpose of this study was to evaluate the MR characteristics of temporomandibular joint (TMJ) disc displacement in elderly patients. Methods Of the MR images of 1660 TMJs in 847 patients with disc displacement who underwent MRI for suspected temporomandibular disorders, 301 TMJs in 154 patients aged over 50 years were studied as an elderly group. These MR images of the elderly group were compared with those of a control group (1359 TMJs in 693 patients aged under 51 years) concerning disc displacement with or without reduction, joint effusion and osteoarthrosis. Results The incidence of disc displacement with osteoarthrosis was significantly different between the elderly (41.9%) and the control (19.8%) groups (p = 0.000). Logistic multivariate regression analysis demonstrated that the osteoarthrosis was a significant variable (odds ratio = 2.94, p = 0.000). Conclusions This study suggests that MR characteristics of TMJ disc displacement in elderly patients includes osteoarthrosis. PMID:22116131

Ogura, I; Kaneda, T; Mori, S; Sakayanagi, M; Kato, M

2012-01-01

284

Enlivening Physics, a Local Video Disc Project.  

ERIC Educational Resources Information Center

Describes how to make and use an inexpensive video disc of physics demonstrations. Discusses the background, production of the disc, subject of the disc including angular momentum, "monkey and the hunter" experiment, Doppler shift, pressure of a constant volume of gas thermometer, and wave effects, and using the disc in classroom. (YP)

McInerney, M.

1989-01-01

285

Imaging of intervertebral disc prostheses.  

PubMed

Disc arthroplasty is the replacement of a painful pathological intervertebral disc by a prosthesis, which, unlike spinal fixation, has the advantage of retaining vertebral mobility in the segment concerned. The success of the procedure is dictated by the indication. The radiologist must look for radiographic arguments indicating or contraindicating fitting an implant, and particularly for the presence of facet arthritis which will prompt the surgeon to choose an arthrodesis. Moreover, radiological information plays a major part in preparing for a surgical procedure, as far as access to the disc via the anterior approach is concerned and assessment by CT angiography of the risk of vascular complications. After insertion, radiological monitoring using dynamic X-ray images checks that the implant is correctly positioned and that mobility is restored. In the long term, it can detect complications related to the prosthesis and premature wear to other points of support such as adjacent discs and the facet joints. PMID:22277706

Amoretti, N; Iannessi, A; Lesbats, V; Marcy, P-Y; Hovorka, E; Bronsard, N; Fonquerne, M-E; Hauger, O

2012-01-01

286

Tissue engineering: A live disc  

NASA Astrophysics Data System (ADS)

A material-cell hybrid device that mimics the anatomic shape of the intervertebral disc has been made and successfully implanted into mice to show that tissue engineering may, in the future, benefit sufferers from back pain.

Hukins, David W. L.

2005-12-01

287

Optic disc edema and Lyme disease.  

PubMed

A seven-year-old child developed a febrile rash, migratory arthritis, and neurologic signs. Three days earlier, the child had been bitten by a tick. An eye examination two months later revealed bilateral papilledema, although the cerebrospinal fluid pressure was 170 mm. The IgM antibody titer for the Ixodes dammini spirochete was 1:256. I dammini is the tick vector for the Borrelia spirochete that causes Lyme disease. The papilledema receded with treatment over a month's time, and bilateral pigment epithelial mottling at the fovea was present after one year. PMID:3767210

Wu, G; Lincoff, H; Ellsworth, R M; Haik, B G

1986-08-01

288

Disc-based immunoassay microarrays  

Microsoft Academic Search

Microarray technology as applied to areas that include genomics, diagnostics, environmental, and drug discovery, is an interesting research topic for which different chip-based devices have been developed. As an alternative, we have explored the principle of compact disc-based microarrays. This new methodology successfully combined high-density microarrays applied via a piezoelectric inkjet applicator with circular indexing on a polycarbonate disc. As

Horacio Kido; Angel Maquieira; Bruce D. Hammock

2000-01-01

289

Planet signatures in collisionally active debris discs: scattered light images  

NASA Astrophysics Data System (ADS)

Context. Planet perturbations have been often invoked as a potential explanation for many spatial structures that have been imaged in debris discs. So far this issue has been mostly investigated with pure N-body numerical models, which neglect the crucial effect collisions within the disc can have on the disc's response to dynamical perturbations. Aims: We numerically investigate how the coupled effect of collisions and radiation pressure can affect the formation and survival of radial and azimutal structures in a disc perturbed by a planet. We consider two different set-ups: a planet embedded within an extended disc and a planet exterior to an inner debris ring. One important issue we want to address is under which conditions a planet's signature can be observable in a collisionally active disc. Methods: We use our DyCoSS code, which is designed to investigate the structure of perturbed debris discs at dynamical and collisional steady-state, and derive synthetic images of the system in scattered light. The planet's mass and orbit, as well as the disc's collisional activity (parameterized by its average vertical optical depth ?0) are explored as free parameters. Results: We find that collisions always significantly damp planet-induced spatial structures. For the case of an embedded planet, the planet's signature, mostly a density gap around its radial position, should remain detectable in head-on images if Mplanet ? MSaturn. If the system is seen edge-on, however, inferring the presence of the planet is much more difficult, as only weak asymmetries remain in a collisionally active disc, although some planet-induced signatures might be observable under very favourable conditions. For the case of an inner ring and an external planet, planetary perturbations cannot prevent collision-produced small fragments from populating the regions beyond the ring. The radial luminosity profile exterior to the ring is in most cases close to the one it should have in the absence of the external planet. The most significant signature left by a Jovian planet on a circular orbit are precessing azimutal structures that can be used to indirectly infer its presence. For a planet on an eccentric orbit, we show that the ring becomes elliptic and that the well known pericentre glow effect is visible despite of collisions and radiation pressure, but that detecting such features in observed discs is not an unambiguous indicator of the presence of an outer planet. Movies are available in electronic form at http://www.aanda.org

Thebault, P.; Kral, Q.; Ertel, S.

2012-11-01

290

Imbalanced Protein Expression Patterns of Anabolic, Catabolic, Anti-Catabolic and Inflammatory Cytokines in Degenerative Cervical Disc Cells: New Indications for Gene Therapeutic Treatments of Cervical Disc Diseases  

PubMed Central

Degenerative disc disease (DDD) of the cervical spine is common after middle age and can cause loss of disc height with painful nerve impingement, bone and joint inflammation. Despite the clinical importance of these problems, in current publications the pathology of cervical disc degeneration has been studied merely from a morphologic view point using magnetic resonance imaging (MRI), without addressing the issue of biological treatment approaches. So far a wide range of endogenously expressed bioactive factors in degenerative cervical disc cells has not yet been investigated, despite its importance for gene therapeutic approaches. Although degenerative lumbar disc cells have been targeted by different biological treatment approaches, the quantities of disc cells and the concentrations of gene therapeutic factors used in animal models differ extremely. These indicate lack of experimentally acquired data regarding disc cell proliferation and levels of target proteins. Therefore, we analysed proliferation and endogenous expression levels of anabolic, catabolic, ant-catabolic, inflammatory cytokines and matrix proteins of degenerative cervical disc cells in three-dimensional cultures. Preoperative MRI grading of cervical discs was used, then grade III and IV nucleus pulposus (NP) tissues were isolated from 15 patients, operated due to cervical disc herniation. NP cells were cultured for four weeks with low-glucose in collagen I scaffold. Their proliferation rates were analysed using 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide. Their protein expression levels of 28 therapeutic targets were analysed using enzyme-linked immunosorbent assay. During progressive grades of degeneration NP cell proliferation rates were similar. Significantly decreased aggrecan and collagen II expressions (P<0.0001) were accompanied by accumulations of selective catabolic and inflammatory cytokines (disintegrin and metalloproteinase with thrombospondin motifs 4 and 5, matrix metalloproteinase 3, interleukin-1?, interleukin-1 receptor) combined with low expression of anti-catabolic factor (metalloproteinase inhibitor 3) (P<0.0001). This study might contribute to inhibit inflammatory catabolism of cervical discs. PMID:24804684

Mern, Demissew S.; Beierfuß, Anja; Fontana, Johann; Thomé, Claudius; Hegewald, Aldemar A.

2014-01-01

291

Clinical Outcomes of Percutaneous Plasma Disc Coagulation Therapy for Lumbar Herniated Disc Diseases  

PubMed Central

Objective This is prospective study of clinical outcomes of percutaneous plasma disc coagulation Therapy (PDCT) in patients with herniated lumbar disc disease (HLD) to evaluate the safety and efficacy in its clinical application and usefulness as a reliable alternative to microscopic discectomy. Methods Forty-six patients were enrolled in this study from April 2006 to June 2010. All patients had one-level HLD. Disc degeneration was graded on routine T2-weighted magnetic resonance Image (MRI) using the Pfirrmann's grading system and all index levels were grade 3 and grade 4. Indications for surgery were radiculopathy caused by disc protrusion with soft consistency. MRI was done at one month after the procedure in all patients to check post-PDCT change. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results This study was approved by the Institutional Review Board of our institution. The age of the study population ranged from 16 to 59 years with a mean age of 37.2 years. There were 29 males and 17 females in this study. The mean period of clinical follow-up was 21 months. The average preoperative VAS score for radiculopathy was 7.4±1.4, while the final follow-up VAS score was 1.4±0.7 (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. Conclusion PDCT is a safe and efficient treatment modality in a selective patient with HLD. PMID:22396836

Kim, Sung Chul; Cho, Ki Hong

2012-01-01

292

Young Stars in the Outer HI Disc of NGC 6822  

E-print Network

We present wide-field optical imaging covering the entire neutral hydrogen disc of the Local Group dwarf galaxy NGC 6822. These observations reveal the presence of numerous blue, young stars at large galactocentric radii well beyond R_25. Blue stars are also found that are associated with NGC 6822's companion HI cloud, indicating that star formation was triggered in the companion in the last 10^8 yr. In general, blue stars are present where the HI surface densities reach values > 5 x 10^20 cm^(-2). However, over one-third of the blue stars detected are found at lower surface densities. The young stars trace the distribution of the neutral hydrogen surprisingly well, but seem to be avoiding the supergiant HI shell in NGC 6822, setting a lower limit for its age of 10^8 yr. The extended distribution of young stars implies that stars can form at large galactocentric radii in dwarf galaxies; the HI is therefore not necessarily much more extended than the stellar population. This finding has important consequences for the chemical enrichment of the interstellar medium throughout (dwarf) galaxies

W. J. G. de Blok; F. Walter

2003-03-28

293

Risk Factors for Recurrent Lumbar Disc Herniations  

PubMed Central

The most common complication after lumbar discectomy is reherniation. As the first step in reducing the rate of recurrence, many studies have been conducted to find out the factors that may increase the reherniation risk. Some reported factors are age, sex, the type of lumbar disc herniation, the amount of fragments removed, smoking, alcohol consumption and the length of restricted activities. In this review, the factors studied thus far are summarized, excepting factors which cannot be chosen or changed, such as age or sex. Apart from the factors shown here, many other risk factors such as diabetes, family history, history of external injury, duration of illness and body mass index are considered. Few are agreed upon by all. The reason for the diverse opinions may be that many clinical and biomechanical variables are involved in the prognosis following operation. For the investigation of risk factors in recurrent lumbar disc herniation, large-scale multicenter prospective studies will be required in the future. PMID:24761206

2014-01-01

294

Effect of Aging on the Mechanical Properties of UV Curable Optical Fiber Coatings  

Microsoft Academic Search

A dual-layer urethane acrylate UV-cured coating is widely used to protect optical fibers because of its well-balanced mechanical properties, weathering resistance and rapid curing. The long-term mechanical behavior of fiber coatings is important for the reliability of optical fibers. Long-term exposure of UV-cured polyether urethane acrylate films was carried out in dry air and in water at elevated temperatures. Tensile

P.-A. Högström; S. Karlsson; U. W. Gedde

2000-01-01

295

A geometrically thin accretion disc around a Maclaurin spheroid  

NASA Astrophysics Data System (ADS)

We investigated a semi-analytic and numerical model to study a geometrically thin and optically thick accretion disc around a Maclaurin spheroid (MS). The main interest is in the inner region of the so-called ?-disc, ? being the viscosity parameter. Analytical calculations are done assuming radiation pressure and gas pressure dominated for close to the Eddington mass accretion rate and dot{M} ? 0.1dot{M}_Edd, respectively. We found that the change in the eccentricity of the MS causes a change at the high-frequency region in the emitted spectra. We found that disc parameters are dependent on the eccentricity of the MS. Our semi-analytic results show that qualitatively an increase in the eccentricity of the MS has the same behaviour as a decrease in the mass accretion rate. Numerical work has been carried out to see the viscous time evolution of the accretion disc around an MS. In a numerical model, we showed that if the eccentricity of an object is high, the matter will diffuse slowly during its viscous evolution. This gives a clue how spin-up or spin-down can change the time evolution of the accretion disc using a simple Newtonian approach. The change in spectra can be used to determine the eccentricity and thus the period of the MS.

Mishra, B.; Vaidya, B.

2015-02-01

296

Preclinical and clinical experience with a viscoelastic total disc replacement  

PubMed Central

Background The purpose of this study is to describe the mechanical durability and the clinical and radiographic outcomes of a viscoelastic total disc replacement (VTDR). The human intervertebral disc is a complex, viscoelastic structure, permitting and constraining motion in 3 axes, thus providing stability. The ideal disc replacement should be viscoelastic and deformable in all directions, and it should restore disc height and angle. Methods Mechanical testing was conducted to validate the durability of the VTDR, and a clinical study was conducted to evaluate safety and performance. Fifty patients with single-level, symptomatic lumbar degenerative disc disease at L4-5 or L5-S1 were enrolled in a clinical trial at 3 European sites. Patients were assessed clinically and radiographically for 2 years by the Oswestry Disability Index (ODI), a visual analog scale (VAS), and independent radiographic analyses. Results The VTDR showed a fatigue life in excess of 50 million cycles (50-year equivalent) and a physiologically appropriate level of stiffness, motion, geometry, and viscoelasticity. We enrolled 28 men and 22 women in the clinical study, with a mean age of 40 years. Independent quantitative radiographic assessment indicated that the VTDR restored and maintained disc height and lordosis while providing physiologic motion. Mean ODI scores decreased from 48% preoperatively to 23% at 2 years’ follow-up. Mean VAS low-back pain scores decreased from 7.1 cm to 2.9 cm. Median scores indicated that half of the patient population had ODI scores below 10% and VAS low-back pain scores below 0.95 cm at 2 years. Conclusions The VTDR has excellent durability and performs clinically and radiographically as intended for the treatment of symptomatic lumbar degenerative disc disease. Clinical Relevance The VTDR is intended to restore healthy anatomic properties and stability characteristics to the spinal segment. This study is the first to evaluate a VTDR in a 50-patient, multicenter European study.

Rischke, Burkhard; Ross, Raymond S.; Jollenbeck, Boris A.; Zimmers, Kari B.; Defibaugh, Neal D.

2011-01-01

297

Early Clinical Experience with the Mobi-C Disc Prosthesis  

PubMed Central

Purpose We have experienced 23 patients who had underwent cervical disc replacement with Mobi-C disc prosthesis and analyzed their radiological results to evaluate its efficacy. Patients and Methods This study was performed on 23 patients with degenerative cervical disc disease who underwent CDR with Mobi-C disc prosthesis from March 2006 to June 2006. Results The age of the study population ranged from 31 to 62 years with mean of 43 years, and 16 male and 7 female cases. Regarding axial pain, the average preoperative VAS score was 6.47 ± 1.4, while at final follow-up it was 1.4 ± 0.7 (p < 0.001). The preoperatively VAS score for radiculopathy was 6.7 ± 0.7 compared with an average score of 0 ± 0 at the final follow-up (p < 0.001). At postoperative 6th month, Odom's criteria were excellent, good, or fair for all 23 patients (100%). 7 patients (30.4%) were classified as excellent, 15 patients (65.2%) as good, and 1 patients (4.4%) as fair. Prolo economic and functional rating scale was average 8.9 ± 0.7 at postoperative 6th month. ROM in C2-7, ROM of FSU, and ROM in upper adjacent level were well preserved after CDR. Conclusion This report would be the first document about the CDR with Mobi-C disc prosthesis in the treatment of degenerative cervical disc disease. CDR with Mobi-C disc prosthesis provided a favorable clinical and radiological outcome in this study. However, Long-term follow-up studies are required to prove its efficacy and ability to prevent adjacent segment disease. PMID:17594154

Kim, Sang Hyun; Shin, Hyun Chul; Shin, Dong Ah; Kim, Keung Nyun

2007-01-01

298

Lumbar degenerative disc disease and tibiotalar joint arthritis: a 710-specimen postmortem study.  

PubMed

Research has associated lumbar spinal disease with lower extremity arthrosis. These studies focused solely on the lumbar spine's connection with hip or knee pathology, failing to investigate potential ankle relationships. We specifically explored the interplay between lumbar disc degeneration and tibiotalar joint arthritis. Lumbar disc degeneration and tibiotalar joint arthritis was graded 0 to 4, according to osteophytosis of the vertebral rim and talar surface in 710 randomly selected cadaveric specimens. We corrected for confounding factors of age, sex, race, and height. A significant association was found between lumbar disc degeneration and tibiotalar joint arthritis (P < .01). Lumbar disc degeneration encompassing 3 intervetebral discs demonstrated the highest odds for development of severe tibiotalar joint arthritis. Severe lumbar degenerative disc disease was more prevalent than severe tibiotalar joint arthritis in individuals age 20 years and older. Furthermore, the presence of severe lumbar degeneration significantly predisposes individuals to the development of severe ankle arthritis (P < .05). Gait changes resulting from disc degeneration or neural compression in the lumbar spine may play a role in ankle osteoarthritis development. This association must be considered when treating patients with lumbar disc degeneration and leg pain. PMID:25844591

Boiwka, Alex V; Bajwa, Navkirat S; Toy, Jason O; Eubanks, Jason; Ahn, Nicholas U

2015-04-01

299

Cone Structure Imaged With Adaptive Optics Scanning Laser Ophthalmoscopy in Eyes With Nonneovascular Age-Related Macular Degeneration  

PubMed Central

Purpose. To evaluate cone spacing using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with nonneovascular AMD, and to correlate progression of AOSLO-derived cone measures with standard measures of macular structure. Methods. Adaptive optics scanning laser ophthalmoscopy images were obtained over 12 to 21 months from seven patients with AMD including four eyes with geographic atrophy (GA) and four eyes with drusen. Adaptive optics scanning laser ophthalmoscopy images were overlaid with color, infrared, and autofluorescence fundus photographs and spectral domain optical coherence tomography (SD-OCT) images to allow direct correlation of cone parameters with macular structure. Cone spacing was measured for each visit in selected regions including areas over drusen (n = 29), at GA margins (n = 14), and regions without drusen or GA (n = 13) and compared with normal, age-similar values. Results. Adaptive optics scanning laser ophthalmoscopy imaging revealed continuous cone mosaics up to the GA edge and overlying drusen, although reduced cone reflectivity often resulted in hyporeflective AOSLO signals at these locations. Baseline cone spacing measures were normal in 13/13 unaffected regions, 26/28 drusen regions, and 12/14 GA margin regions. Although standard clinical measures showed progression of GA in all study eyes, cone spacing remained within normal ranges in most drusen regions and all GA margin regions. Conclusions. Adaptive optics scanning laser ophthalmoscopy provides adequate resolution for quantitative measurement of cone spacing at the margin of GA and over drusen in eyes with AMD. Although cone spacing was often normal at baseline and remained normal over time, these regions showed focal areas of decreased cone reflectivity. These findings may provide insight into the pathophysiology of AMD progression. (ClinicalTrials.gov number, NCT00254605.) PMID:24135755

Zayit-Soudry, Shiri; Duncan, Jacque L.; Syed, Reema; Menghini, Moreno; Roorda, Austin J.

2013-01-01

300

Correlation of Choroidal Thickness and Volume Measurements with Axial Length and Age Using Swept Source Optical Coherence Tomography and Optical Low-Coherence Reflectometry  

PubMed Central

Purpose. To report choroidal thickness and volume in healthy eyes using swept source optical coherence tomography (SS-OCT). Methods. A prospective observational study of 122 patients examined with swept source OCT (DRI-OCT, Topcon, Japan). In each eye, we performed 256 horizontal scans, 12?mm in length and centered on the fovea. We calculated choroidal thickness manually with a built-in caliper and automatically using DRI-OCT mapping software. Choroidal volume was also automatically calculated. We measured axial length with optical low-coherence reflectometry (Lenstar LS 900, Haag-Streit, Switzerland). Results. The choroid has focally increased thickness under the fovea. Choroid was thinnest in the outer nasal quadrant. In stepwise regression analysis, age was estimated as the most significant factor correlating with decreased choroidal thickness (F = 23.146, P < 0.001) followed by axial length (F = 4.902, P = 0.03). Refractive error was not statistically significant (F = 1.16, P = 0.28). Conclusions. SS-OCT is the first commercially available system that can automatically create choroidal thickness and volume maps. Choroidal thickness is increased at the fovea and is thinnest nasally. Age and axial length are critical for the estimation of choroidal thickness and volume. Choroidal measurements derived from SS-OCT images have potential value for objectively documenting disease-related choroidal thickness abnormalities and monitoring progressive changes over time. PMID:25013793

Michalewski, Janusz; Nawrocka, Zofia; Bednarski, Maciej; Nawrocki, Jerzy

2014-01-01

301

Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA  

NASA Astrophysics Data System (ADS)

Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2 ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26 m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2 ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism.

Mallinson, David; Burdette, Kevin; Mahan, Shannon; Brook, George

2008-01-01

302

Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA  

USGS Publications Warehouse

Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2??ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26??m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2??ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism. ?? 2007 University of Washington.

Mallinson, D.; Burdette, K.; Mahan, S.; Brook, G.

2008-01-01

303

Topology of magnetic field and polarization in accretion discs of AGN  

NASA Astrophysics Data System (ADS)

In this paper we demonstrate that the wavelength dependence of polarization degree and position angle allows us to derive the distribution of magnetic field in accretion disc. The polarized radiation arises due to scattering of emission light by electrons in a magnetized optically thick accretion disc. Faraday rotation of polarization plane is taken into consideration. Through wavelength dependence of polarization it is possible to derive the value of the magnetic Prandtl number in the accretion disc plasma. The power law index of the polarization wavelength dependence is related with the radial distribution of magnetic field in an accretion disc. This allows us to test the various models of an accretion disc around the central black hole.

Gnedin, Y. N.; Buliga, S. D.; Silant'ev, N. A.; Natsvlishvili, T. M.; Piotrovich, M. Y.

2012-11-01

304

Irradiated accretion discs in ultraluminous X-ray sources  

NASA Astrophysics Data System (ADS)

Observations of optical counterparts to ultraluminous X-ray sources (ULXs) could provide critical clues to the physical nature of these extraordinary objects. Recently attempts have been made to constrain the stellar types of ULX counterparts, however the detection of optical variability suggests that they may actually be dominated by reprocessed X-ray emission. Here, we report on a combined XMM-Newton and HST study of ULXs with broadened disc-like X-ray spectra. We fit the data with a new spectral model of emission from an irradiated, colour-temperature-corrected accretion disc with a Comptonising corona, finding reprocessing fractions similar to the high/soft state black hole binaries (BHBs), but less than has been reported for some ULXs with soft, wind-dominated X-ray spectra. We suggest that X-ray emission may be scattered on to the outer disc by material in a natal super-Eddington wind, then the higher reprocessing fractions in some ULXs may be associated with stronger winds. Alternatively, these disc-like ULXs may be similar in geometry to the high/soft state BHBs.

Sutton, A.; Roberts, T.; Done, C.

2014-07-01

305

Prosthetic lumbar disc replacement for degenerative disc disease.  

PubMed

Mechanical articulated device to replace intervertebral disc as a treatment for low back pain secondary to disc degeneration has emerged as a promising tool for selected patients. The potential advantages are prevention of adjacent segment degeneration, maintenance of mobility as well as avoidance of all the complications associated with fusion. The short-term results have been comparable to that of fusion, a few mid-term results have shown mixed outcome, but information on long-term results and performance are not available at present. The rationale for lumbar disc arthroplasty, indications, contraindications, the various artificial devices in the market and the concepts intrinsic to each of them, basic technique of insertion, complications are discussed and a brief summary of our experience with one of the devices is presented. PMID:16565543

Kulkarni, Arvind G; Diwan, Ashish D

2005-12-01

306

Aging of savanna biomass burning aerosols: Consequences on their optical properties  

Microsoft Academic Search

During the FOS-DECAFE experiment at Lamto, Ivory Coast, in January 1991, various ground studies were undertaken simultaneously in order to investigate the physical and chemical characteristics of smoke emitted by savanna biomass burning. Here we present sunphotometer ground-based results which allow the measurements of the spectral optical depth between 450 and 850 nm, the atmospheric water vapour content and the

C. Liousse; C. Devaux; F. Dulac; H. Cachier

1995-01-01

307

Changes in mechanical behaviour of optical fibers aged in surfactant solutions  

NASA Astrophysics Data System (ADS)

A solution containing surfactants presents appreciable changes in physical and chemical properties at the critical micelle concentration (CMC). Besides signal transmission for telecommunications, optical fibers are used in an increasing number of devices. Among different CMC determination techniques, optical fiber sensors have been increasingly used. However, reliability issues must be addressed for optical fiber sensors operating under particular conditions such as immersion in surfactants at CMC. The purpose of this work was to study the mechanical behavior of both silica coated and naked fibers in contact with two surfactants (sodium dodecyl sulphate (SDS) and Triton X-100) at the critical micelle concentration. Fatigue tests were implemented using a tensile test set-up. Optical fibers were wound onto pulleys and submitted to a tensile test using different velocities. Result analysis proves that immersion in SDS and Triton X-100 decreased the fiber strength especially near the CMC point. Beyond the CMC point, a fine surfactant molecule layer covered all the fiber surfaces and led to a small increase of fiber strength.

El Abdi, R.; Poulain, M.

2012-09-01

308

Subaru optical observations of the two middle-aged pulsars PSR B0656+14 and Geminga  

E-print Network

We carried out a deep subarcsecond BRI imaging of the two middle-aged pulsars to establish their properties in the optical range. Both pulsars are detected at >10 sigma level. Geminga is for the first time reliably detected in the I band with a magnitude of 25.10+/-0.14. We also reanalyze archival ESO/NTT and HST broadband data and find that some published fluxes for Geminga were estimated inaccurately. The resulting dereddened broadband spectra of both pulsars are remarkably similar to each other and show significant flux increases towards the far-UV and near-IR, and a wide flux excess in V-I bands. This suggests a multicomponent structure of the optical emission. The nonthermal power law component of the pulsar magnetospheric origin dominates in the most part of the optical range. For PSR B0656+14 it is compatible with a low energy extension of the power law tail seen in hard X-rays. For Geminga the respective extension overshoots by a factor of 100 the nonthermal optical flux, which has a less steep spectral slope than in X-rays. This implies a spectral break at a photon energy of about 1 keV. The flux increases towards the far-UV are compatible with contributions of the Rayleigh-Jeans parts of the blackbody components from whole surfaces of the neutron stars dominating in soft X-rays. The V-I excess, which is most significant for PSR B0656+14, suggests a third spectral component of still unidentified origin. Faint, a few arcseconds in size nebulae extended perpendicular to the proper motion directions of the pulsars, are seen around both objects in our deepest I band images. They can be optical counterparts of the bow-shock head of Geminga and of the tentative pulsar wind nebula of PSR B0656+14 observed in X-rays.

Yuri A. Shibanov; Sergei V. Zharikov; Viktoria N. Komarova; Nobuyuki Kawai; Yuji Urata; Alexey B. Koptsevich; Vladimir V. Sokolov; Shinpei Shibata; Noriaki Shibazaki

2005-11-09

309

The nature of the red disc-like galaxies at high redshift: dust attenuation and intrinsically red stellar populations  

NASA Astrophysics Data System (ADS)

We investigate which conditions of dust attenuation and stellar populations allow models of dusty, continuously star-forming, bulge-less disc galaxies at 0.8 <~z<~ 3.2 to meet the different colour selection criteria of high-z`red' galaxies (e.g. RC-K > 5.3, IC-K > 4, J-K > 2.3). As a main novelty, we use stellar population models that include the thermally pulsating asymptotic giant branch (TP-AGB) phase of stellar evolution. The star formation rate of the models declines exponentially as a function of time, the e-folding time being longer than 3 Gyr. In addition, we use calculations of radiative transfer of the stellar and scattered radiation through different dusty interstellar media in order to explore the wide parameter space of dust attenuation. We find that synthetic discs can exhibit red optical/near-infrared colours because of reddening by dust, but only if they have been forming stars for at least ~1 Gyr. Extremely few models barely exhibit RC-K > 5.3, if the inclination i= 90° and if the opacity 2 ×?V>~ 6. Hence, RC-K-selected galaxies at 1 <~z<~ 2 most probably are either systems with an old, passively evolving bulge or starbursts. Synthetic discs at 1 <~z<~ 2 exhibit 4 < IC-K < 4.8, if they are seen edge on (i.e. at i~ 90°) and if 2 ×?V>~ 0.5. This explains the large fraction of observed, edge-on disc-like galaxies with Ks < 19.5 and F814W-Ks>~ 4. Finally, models with 2 <~z<~ 3.2 exhibit 2.3 < J-K < 3, with no bias towards i~ 90° and for a large range in opacity (e.g. 2 ×?V > 1 for i~ 70°). In conclusion, red disc-like galaxies at 0.8 <~z<~ 3.2 may not necessarily be dustier than nearby disc galaxies (with 0.5 <~ 2 ×?V<~ 2) and/or much older than ~1 Gyr. This result is due both to a realistic description of dust attenuation and to the emission contribution by TP-AGB stars, with ages of 0.2 to 1-2 Gyr and intrinsically red colours.

Pierini, D.; Maraston, C.; Gordon, K. D.; Witt, A. N.

2005-10-01

310

Debris disc formation induced by planetary growth  

NASA Astrophysics Data System (ADS)

Several hundred stars older than 10 million years have been observed to have infrared excesses. These observations are explained by dust grains formed by the collisional fragmentation of hidden planetesimals. Such dusty planetesimal discs are known as debris discs. In a dynamically cold planetesimal disc, collisional coagulation of planetesimals produces planetary embryos which then stir the surrounding leftover planetesimals. Thus, the collisional fragmentation of planetesimals that results from planet formation forms a debris disc. We aim to determine the properties of the underlying planetesimals in debris discs by numerically modelling the coagulation and fragmentation of planetesimal populations. The brightness and temporal evolution of debris discs depend on the radial distribution of planetesimal discs, the location of their inner and outer edges, their total mass, and the size of planetesimals in the disc. We find that a radially narrow planetesimal disc is most likely to result in a debris disc that can explain the trend of observed infrared excesses of debris discsvvv around G-type stars, for which planet formation occurs only before 100 million years. Early debris disc formation is induced by planet formation, while the later evolution is explained by the collisional decay of leftover planetesimals around planets that have already formed. Planetesimal discs with underlying planetesimals of radii ˜100 km at ?30 au most readily explain the Spitzer Space Telescope 24 and 70 ?m fluxes from debris discs around G-type stars.

Kobayashi, H.; Löhne, T.

2014-08-01

311

Potential regenerative treatment strategies for intervertebral disc degeneration in dogs  

PubMed Central

Pain due to spontaneous intervertebral disc (IVD) disease is common in dogs. In chondrodystrophic (CD) dogs, IVD disease typically develops in the cervical or thoracolumbar spine at about 3–7 years of age, whereas in non-chondrodystrophic (NCD) dogs, it usually develops in the caudal cervical or lumbosacral spine at about 6–8 years of age. IVD degeneration is characterized by changes in the biochemical composition and mechanical integrity of the IVD. In the degenerated IVD, the content of glycosaminoglycan (GAG, a proteoglycan side chain) decreases and that of denatured collagen increases. Dehydration leads to tearing of the annulus fibrosus (AF) and/or disc herniation, which is clinically characterized by pain and/or neurological signs. Current treatments (physiotherapy, anti-inflammatory/analgesic medication, surgery) for IVD disease may resolve neurological deficits and reduce pain (although in many cases insufficient), but do not lead to repair of the degenerated disc. For this reason, there is interest in new regenerative therapies that can repair the degenerated disc matrix, resulting in restoration of the biomechanical function of the IVD. CD dogs are considered a suitable animal model for human IVD degeneration because of their spontaneous IVD degeneration, and therefore studies investigating cell-, growth factor-, and/or gene therapy-based regenerative therapies with this model provide information relevant to both human and canine patients. The aim of this article is to review potential regenerative treatment strategies for canine IVD degeneration, with specific emphasis on cell-based strategies. PMID:24387033

2014-01-01

312

Potential regenerative treatment strategies for intervertebral disc degeneration in dogs.  

PubMed

Pain due to spontaneous intervertebral disc (IVD) disease is common in dogs. In chondrodystrophic (CD) dogs, IVD disease typically develops in the cervical or thoracolumbar spine at about 3-7 years of age, whereas in non-chondrodystrophic (NCD) dogs, it usually develops in the caudal cervical or lumbosacral spine at about 6-8 years of age. IVD degeneration is characterized by changes in the biochemical composition and mechanical integrity of the IVD. In the degenerated IVD, the content of glycosaminoglycan (GAG, a proteoglycan side chain) decreases and that of denatured collagen increases. Dehydration leads to tearing of the annulus fibrosus (AF) and/or disc herniation, which is clinically characterized by pain and/or neurological signs. Current treatments (physiotherapy, anti-inflammatory/analgesic medication, surgery) for IVD disease may resolve neurological deficits and reduce pain (although in many cases insufficient), but do not lead to repair of the degenerated disc. For this reason, there is interest in new regenerative therapies that can repair the degenerated disc matrix, resulting in restoration of the biomechanical function of the IVD. CD dogs are considered a suitable animal model for human IVD degeneration because of their spontaneous IVD degeneration, and therefore studies investigating cell-, growth factor-, and/or gene therapy-based regenerative therapies with this model provide information relevant to both human and canine patients. The aim of this article is to review potential regenerative treatment strategies for canine IVD degeneration, with specific emphasis on cell-based strategies. PMID:24387033

Bach, Frances C; Willems, Nicole; Penning, Louis C; Ito, Keita; Meij, Björn P; Tryfonidou, Marianna A

2014-01-01

313

THE EFFECT OF ACCELERATED AGING TESTS ON THE OPTICAL PROPERTIES OF SILICONE AND EVA ENCAPSULANTS  

Microsoft Academic Search

The absorption coefficient of three silicones and EVA is measured before and after exposure to three accelerated aging tests: (i) ~2000 hours under Xe-arc lamp exposure at room temperature, (ii) 1200 hours at 85% relative humidity and 85 °C, and (iii) six months at the focal point of a 30× linear tracker. The first exposure satisfied the IEC's UV conditioning

Keith R. McIntosh; James N. Cotsell; Jeff S. Cumpston; Ann W. Norris; Nick E. Powell; Barry M. Ketola

314

Quantitative analysis of three-dimensional fibrillar collagen microstructure within the normal, aged and glaucomatous human optic nerve head.  

PubMed

The aim of this study was to quantify connective tissue fibre orientation and alignment in young, old and glaucomatous human optic nerve heads (ONH) to understand ONH microstructure and predisposition to glaucomatous optic neuropathy. Transverse (seven healthy, three glaucomatous) and longitudinal (14 healthy) human ONH cryosections were imaged by both second harmonic generation microscopy and small angle light scattering (SALS) in order to quantify preferred fibre orientation (PFO) and degree of fibre alignment (DOFA). DOFA was highest within the peripapillary sclera (ppsclera), with relatively low values in the lamina cribrosa (LC). Elderly ppsclera DOFA was higher than that in young ppsclera (p < 0.00007), and generally higher than in glaucoma ppsclera. In all LCs, a majority of fibres had preferential orientation horizontally across the nasal-temporal axis. In all glaucomatous LCs, PFO was significantly different from controls in a minimum of seven out of 12 LC regions (p < 0.05). Additionally, higher fibre alignment was observed in the glaucomatous inferior-temporal LC (p < 0.017). The differences between young and elderly ONH fibre alignment within regions suggest that age-related microstructural changes occur within the structure. The additional differences in fibre alignment observed within the glaucomatous LC may reflect an inherent susceptibility to glaucomatous optic neuropathy, or may be a consequence of ONH remodelling and/or collapse. PMID:25808336

Jones, H J; Girard, M J; White, N; Fautsch, M P; Morgan, J E; Ethier, C R; Albon, J

2015-05-01

315

History of cervical disc arthroplasty.  

PubMed

Enthusiasm for cervical disc arthroplasty is based on the premise that motion-preserving devices attenuate the progression of adjacent-segment disease (ASD) in the cervical spine. Arthrodesis, on the other hand, results in abnormal load transfer on adjacent segments, leading to the acceleration of ASD. It has taken several decades of pioneering work to produce clinically relevant devices that mimic the kinematics of the intervertebral disc. The goal of this work is to trace the origins of cervical arthroplasty technology and highlight the attributes of devices currently available in the market. PMID:19722812

Baaj, Ali A; Uribe, Juan S; Vale, Fernando L; Preul, Mark C; Crawford, Neil R

2009-09-01

316

Optical properties of aged Asian aerosols observed over the U.S. Pacific Northwest  

NASA Astrophysics Data System (ADS)

A suite of gas-phase and aerosol measurements were made during spring 2008 and spring 2009 at the Mount Bachelor Observatory (2763 masl), located in Oregon. Here we focus on multiwavelength observations of low RH submicron (?m) aerosol scattering (?sp) and absorption (?ap), made with an integrating nephelometer and a particle soot absorption photometer. Using a combination of in situ observations, trajectory calculations and satellite observations, we identified seven plumes of Asian origin. These plumes included many of the highest ?sp (34.8 Mm-1) and ?ap (5.7 Mm-1) hourly average values observed at MBO over the 2008 and 2009 campaigns. Of interest in this analysis is (1) whether the intensive optical properties differ between these seven plumes, (2) whether these differences can be linked to differences in composition, and (3) whether the intensive optical properties change during transpacific transport. Results show that the plumes clustered in terms of their optical properties; plumes hypothesized to contain a large fraction of mineral dust were the most distinct. We observed variability between plumes in the scattering Ångström (Ås) exponent. The average submicrometer Ås for all seven plumes was significantly larger than the same parameter observed closer to Asia. Therefore, we hypothesize that the aerosol size distribution shifts toward smaller particles during transpacific transport. The average submicrometer low-RH aerosol single scatter albedo (?) observed at MBO (0.88) was slightly larger than previous observations closer to the Asian coast, and the average backscatter fraction (b) was smaller, on the order of 20%.

Fischer, E. V.; Jaffe, D. A.; Marley, N. A.; Gaffney, J. S.; Marchany-Rivera, A.

2010-10-01

317

The chemical compositions of Galactic disc F and G dwarfs  

NASA Astrophysics Data System (ADS)

Photospheric abundances are presented for 27 elements from carbon to europium in 181 F and G dwarfs from a differential local thermodynamic equilibrium (LTE) analysis of high-resolution and high signal-to-noise ratio spectra. Stellar effective temperatures (Teff) were adopted from an infrared flux method calibration of Strömgren photometry. Stellar surface gravities (g) were calculated from Hipparcos parallaxes and stellar evolutionary tracks. Adopted Teff and g values are in good agreement with spectroscopic estimates. Stellar ages were determined from evolutionary tracks. Stellar space motions (U, V, W) and a Galactic potential were used to estimate Galactic orbital parameters. These show that the vast majority of the stars belong to the Galactic thin disc. Relative abundances expressed as [X/Fe] generally confirm previously published results. We give results for C, N, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu. The ? elements - O, Mg, Si, Ca and Ti - show [?/Fe] to increase slightly with decreasing [Fe/H]. Heavy elements with dominant contributions at solar metallicity from the s-process show [s/Fe] to decrease slightly with decreasing [Fe/H]. Scatter in [X/Fe] at a fixed [Fe/H] is entirely attributable to the small measurement errors, after excluding the few thick disc stars and the s-process-enriched CH subgiants. Tight limits are set on `cosmic' scatter. If a weak trend with [Fe/H] is taken into account, the composition of a thin disc star expressed as [X/Fe] is independent of the star's age and birthplace for elements contributed in different proportions by massive stars (Type II supernovae), exploding white dwarfs (Type Ia supernovae) and asymptotic red giant branch stars. By combining our sample with various published studies, comparisons between thin and thick disc stars are made. In this composite sample, thick disc stars are primarily identified by their VLSR in the range -40 to -100 km s-1. These are very old stars with origins in the inner Galaxy and metallicities [Fe/H]<=-0.4. At the same [Fe/H], the sampled thin disc stars have VLSR~ 0 km s-1, and are generally younger with a birthplace at about the Sun's Galactocentric distance. In the range -0.35 >=[Fe/H]>=-0.70, well represented by present thin and thick disc samples, [X/Fe] of the thick disc stars is greater than that of thin disc stars for Mg, Al, Si, Ca, Ti and Eu. [X/Fe] is very similar for the thin and thick disc for - notably - Na and iron-group elements. Barium ([Ba/Fe]) may be underabundant in thick relative to thin disc stars. These results extend previous ideas about composition differences between the thin and thick disc.

Reddy, Bacham E.; Tomkin, Jocelyn; Lambert, David L.; Allende Prieto, Carlos

2003-03-01

318

46 CFR 64.61 - Rupture disc.  

Code of Federal Regulations, 2010 CFR

...SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank,...

2010-10-01

319

46 CFR 64.61 - Rupture disc.  

Code of Federal Regulations, 2012 CFR

...SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank,...

2012-10-01

320

46 CFR 64.61 - Rupture disc.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank,...

2011-10-01

321

46 CFR 64.61 - Rupture disc.  

Code of Federal Regulations, 2014 CFR

...SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank,...

2014-10-01

322

46 CFR 64.61 - Rupture disc.  

Code of Federal Regulations, 2013 CFR

...SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank,...

2013-10-01

323

Laser microbeams for DNA damage induction, optical tweezers for the search on blood pressure relaxing drugs: contributions to ageing research  

NASA Astrophysics Data System (ADS)

One essential cause of human ageing is the accumulation of DNA damages during lifetime. Experimental studies require quantitative induction of damages and techniques to visualize the subsequent DNA repair. A new technique, the "immuno fluorescent comet assay", is used to directly visualize DNA damages in the microscope. Using DNA repair proteins fluorescently labeled with green fluorescent protein, it could be shown that the repair of the most dangerous DNA double strand breaks starts with the inaccurate "non homologous end joining" pathway and only after 1 - 1 ½ minutes may switch to the more accurate "homologous recombination repair". One might suggest investigating whether centenarians use "homologous recombination repair" differently from those ageing at earlier years and speculate whether it is possible, for example by nutrition, to shift DNA repair to a better use of the error free pathway and thus promote healthy ageing. As a complementary technique optical tweezers, and particularly its variant "erythrocyte mediated force application", is used to simulate the effects of blood pressure on HUVEC cells representing the inner lining of human blood vessels. Stimulating one cell induces in the whole neighbourhood waves of calcium and nitric oxide, known to relax blood vessels. NIFEDIPINE and AMLODIPINE, both used as drugs in the therapy of high blood pressure, primarily a disease of the elderly, prolong the availability of nitric oxide. This partially explains their mode of action. In contrast, VERAPAMILE, also a blood pressure reducing drug, does not show this effect, indicating that obviously an alternative mechanism must be responsible for vessel relaxation.

Grigaravicius, P.; Monajembashi, S.; Hoffmann, M.; Altenberg, B.; Greulich, K. O.

2009-08-01

324

Write Strategy Optimization Method with Two-Step Search for Blu-ray Disc Recording  

Microsoft Academic Search

A new write strategy (WS) optimization method with a two-step search process for Blu-ray Disc (BD) recording is developed to shorten the optimization time. This method is realized by the WS optimization system, which is constructed with an optical pickup, a disc tester, and the WS optimization algorithm. The optimization is executed according to the two-step search process along the

Nobuo Takeshita; Yusuke Kanatake; Tomo Kishigami; Koichi Ikuta

2010-01-01

325

Modeling and robust control of Blu-ray disc servo-mechanisms  

Microsoft Academic Search

This paper deals with the modeling and the robust control of the next generation of optical disc drives servo-mechanisms. While in many industrial servo-control implementations, the radial and focus loops are considered as decoupled, e.g. DVD drives, this is no longer true for HD-DVD and Blu-ray disc (BD) formats which are more sensitive to opto-mechanical interactions at high frequencies. The

John J. Martinez; Olivier Sename; Alina Voda

2009-01-01

326

Optical Head Using Single Objective Lens for Four Types of Optical Disks  

Microsoft Academic Search

An optical head using a single objective lens for Blu-ray disc (BD), high-density digital versatile disc (HD DVD), digital versatile disc (DVD), and compact disc (CD) has been developed, which is suitable for high-speed recording and reading. A relay lens unit, which consists of two convex lenses and one concave lens, corrects the spherical aberration and realizes high light power

Ryuichi Katayama; Yuichi Komatsu

2008-01-01

327

Autotraction in lumbar disc herniation  

Microsoft Academic Search

Autotraction is a method of diminishing lower back pain and sciatica in which the patient stretches himself on a specially designed traction table. The pulling force ranges between 400–800 N. Clinical results are encouraging and the method can be recommended as a temporary treatment especially in lumbago with sciatica. The influence on a herniated disc is discussed with respect to

P. Gillström; K. Ericson; T. Hindmarsh

1985-01-01

328

Intramural Sports Ultimate Disc "Hat"  

E-print Network

Intramural Sports Ultimate Disc "Hat" Tournament Summer 2014 Intramural Sports Calendar of Events on the day of the tournament, teams will be drawn out of a hat and mixed for play. Sports and Special or Faculty/Staff/Affiliates with a Recreational Sports Membership are eligible to participate. http://oregonstate.edu/recsports/intramural-sports

Escher, Christine

329

Circumstellar discs around A stars  

NASA Astrophysics Data System (ADS)

Since the IRAS mission it is known that a couple of nearby young stars are surrounded by dust disks (Aumann 1995); two prominent examples are Vega and \\beta Pictoris. CO radio observations of these stars, carried out to trace the gas component of these disks, revealed a strong depletion of CO (Dent et al. 1995). This has been interpreted as a general gas depletion, and models for the formation of gas-giant planets have been called in question. Detailed disc models concentrating on the discs' gas component show that CO has been selectively depleted in the dusty and gaseous discs by photodissociation and freezing out of CO on the cold dust grain surfaces (Rentzsch-Holm, Holweger & Bertoldi (1998), Kamp & Bertoldi 1998). We will now compare our models with the observation to fix the remaining free parameters. The disc mass, the main free parameter, can be inferred from modeling the infrared excess using dust models with various grain sizes and chemical composition. References: Aumann, H.H. 1985. PASP 97, 885 Dent, W.R.F., et al. 1995. MNRAS 277, L25 Rentzsch-Holm, I., Holweger, H., Bertoldi, F. 1998. ASP Conference Series 132, 275 Kamp, I., Bertoldi, F. 1998. in preparation

Kamp, I.; Holweger, H.; Bertoldi, I.

330

Electromagnetic Levitation of a Disc  

ERIC Educational Resources Information Center

This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

2012-01-01

331

Wnt Signaling Activates Shh Signaling in Early Postnatal Intervertebral Discs, and Re-Activates Shh Signaling in Old Discs in the Mouse  

PubMed Central

Intervertebral discs (IVDs) are strong fibrocartilaginous joints that connect adjacent vertebrae of the spine. As discs age they become prone to failure, with neurological consequences that are often severe. Surgical repair of discs treats the result of the disease, which affects as many as one in seven people, rather than its cause. An ideal solution would be to repair degenerating discs using the mechanisms of their normal differentiation. However, these mechanisms are poorly understood. Using the mouse as a model, we previously showed that Shh signaling produced by nucleus pulposus cells activates the expression of differentiation markers, and cell proliferation, in the postnatal IVD. In the present study, we show that canonical Wnt signaling is required for the expression of Shh signaling targets in the IVD. We also show that Shh and canonical Wnt signaling pathways are down-regulated in adult IVDs. Furthermore, this down-regulation is reversible, since re-activation of the Wnt or Shh pathways in older discs can re-activate molecular markers of the IVD that are lost with age. These data suggest that biological treatments targeting Wnt and Shh signaling pathways may be feasible as a therapeutic for degenerative disc disease. PMID:24892825

Sinner, Debora; Wylie, Christopher C.; Dahia, Chitra Lekha

2014-01-01

332

Wnt signaling activates Shh signaling in early postnatal intervertebral discs, and re-activates Shh signaling in old discs in the mouse.  

PubMed

Intervertebral discs (IVDs) are strong fibrocartilaginous joints that connect adjacent vertebrae of the spine. As discs age they become prone to failure, with neurological consequences that are often severe. Surgical repair of discs treats the result of the disease, which affects as many as one in seven people, rather than its cause. An ideal solution would be to repair degenerating discs using the mechanisms of their normal differentiation. However, these mechanisms are poorly understood. Using the mouse as a model, we previously showed that Shh signaling produced by nucleus pulposus cells activates the expression of differentiation markers, and cell proliferation, in the postnatal IVD. In the present study, we show that canonical Wnt signaling is required for the expression of Shh signaling targets in the IVD. We also show that Shh and canonical Wnt signaling pathways are down-regulated in adult IVDs. Furthermore, this down-regulation is reversible, since re-activation of the Wnt or Shh pathways in older discs can re-activate molecular markers of the IVD that are lost with age. These data suggest that biological treatments targeting Wnt and Shh signaling pathways may be feasible as a therapeutic for degenerative disc disease. PMID:24892825

Winkler, Tamara; Mahoney, Eric J; Sinner, Debora; Wylie, Christopher C; Dahia, Chitra Lekha

2014-01-01

333

A miniature fiber optic pressure sensor for intradiscal pressure measurements of rodents  

NASA Astrophysics Data System (ADS)

Lower back pain continues to be a leading cause of disability in people of all ages, and has been associated with degenerative disc disease. It is well accepted that mechanical stress, among other factors, can play a role in the development of disc degeneration. Pressures generated in the intervertebral disc have been measured both in vivo and in vitro for humans and animals. However, thus far it has been difficult to measure pressure experimentally in rodent discs due to their small size. With the prevalent use of rodent tail disc models in mechanobiology, it is important to characterize the intradiscal pressures generated with externally applied stresses. In this paper, a miniature fiber optic Fabry-Perot interferometric pressure sensor with an outer diameter of 360 ?m was developed to measure intradiscal pressures in rat caudal discs. A low coherence interferometer based optical system was used, which includes a broadband light source, a high-speed spectrometer, and a Fabry-Perot sensor. The sensor employs a capillary tube, a flexible, polymer diaphragm coated with titanium as a partial mirror, and a fiber tip as another mirror. The pressure induced deformation of the diaphragm results in a cavity length change of the Fabry-Perot interferometer which can be calculated from the wavelength shift of interference fringes. The sensor exhibited good linearity with small applied pressures. Our validation experiments show that owing to the small size, inserting the sensor does not disrupt the annulus fibrosus and will not alter intradiscal pressures generated. Measurements also demonstrate the feasibility of using this sensor to quantify external load intradiscal pressure relationships in small animal discs.

Nesson, Silas; Yu, Miao; Hsieh, Adam H.

2007-04-01

334

Modelling the Milky Way disc  

NASA Astrophysics Data System (ADS)

RAVE, SEGUE and Hipparcos data are used to study the dynamics of stars in the extended solar neighbourhood. The asymmetric drift of thin disc dwarfs is studied as a function of colour and metallicity. Linear extrapolation of the data falls within the error bars from Aumer & Binney (2009) for local standard of rest. The observed metallicity dependence of the asymmetric drift is consistent with the known radial metallicity distribution in the disc. Implying the asymmetric drift correction to the SEGUE data allows us to reconstruct the behaviour of the rotation curve of the Milky Way in the extended solar neighbourhood. The rotation curve appears to be essentially flat, giving no hint for a dip just outside the solar radius followed by an increase observed in some other data sets. The data are supplemented by tangent point measurements for the inner rotation curve. Thus a synthetic rotation curve of the Milky Way is obtained. It is fitted by a density model consisting of a D! ehnen bulge, an exponential disc with a hole, and a flattened dark matter halo with either cored isothermal or NFW density profile. In this fitting the parameters are constrained to reproduce the local surface density of the disc and the local volume density of the halo, which are known from local stellar dynamics in the solar neighbourhood. Thus the density model of the Milky Way is reconstructed. The vertical structure of the disc of theMilkyWay is consistent with the model by Just & Jahreiß (2010). Some basic features of distribution functions of the Milky Way and of the dynamical heating are also discussed.

Golubov, Oleksiy

2012-10-01

335

Evolution of linear warps in accretion discs and applications to protoplanetary discs in binaries  

NASA Astrophysics Data System (ADS)

Warped accretion discs are expected in many protostellar binary systems. In this paper, we study the long-term evolution of disc warp and precession for discs with dimensionless thickness H/r larger than their viscosity parameter ?, such that bending waves can propagate and dominate the warp evolution. For small warps, these discs undergo approximately rigid-body precession. We derive analytical expressions for the warp/twist profiles of the disc and the alignment time-scale for a variety of models. Applying our results to circumbinary discs, we find that these discs align with the orbital plane of the binary on a time-scale comparable to the global precession time of the disc, and typically much smaller than its viscous time-scale. We discuss the implications of our finding for the observations of misaligned circumbinary discs (such as KH 15D) and circumbinary planetary systems (such as Kepler-413); these observed misalignments provide useful constraints on the uncertain aspects of the disc warp theory. On the other hand, we find that circumstellar discs can maintain large misalignments with respect to the plane of the binary companion over their entire lifetime. We estimate that inclination angles larger than ˜20° can be maintained for typical disc parameters. Overall, our results suggest that while highly misaligned circumstellar discs in binaries are expected to be common, such misalignments should be rare for circumbinary discs. These expectations are consistent with current observations of protoplanetary discs and exoplanets in binaries, and can be tested with future observations.

Foucart, Francois; Lai, Dong

2014-12-01

336

Sealing arrangement with annular flexible disc  

DOEpatents

Fluid sealing arrangements including an annular shaped flexible disc having enlarged edges disposed within channel-shaped annular receptacles which are spaced from one another. The receptacles form an annular region for contacting and containing the enlarged edges of the disc, and the disc is preloaded to a conical configuration. The disc is flexibly and movably supported within the receptacles so that unevenly distributed relative motion between the components containing the receptacles is accommodated without loss of sealing contact between the edges of the disc and the walls of the receptacles.

Pennell, William E. (Greensburg, PA); Honigsberg, Charles A. (Monroeville, PA)

1983-01-01

337

Segmentation and quantification of retinal lesions in age-related macular degeneration using polarization-sensitive optical coherence tomography  

NASA Astrophysics Data System (ADS)

We present polarization-sensitive optical coherence tomography (PS-OCT) for quantitative assessment of retinal pathologies in age-related macular degeneration (AMD). On the basis of the polarization scrambling characteristics of the retinal pigment epithelium, novel segmentation algorithms were developed that allow one to segment pathologic features such as drusen and atrophic zones in dry AMD as well as to determine their dimensions. Results from measurements in the eyes of AMD patients prove the ability of PS-OCT for quantitative imaging based on the retinal features polarizing properties. Repeatability measurements were performed in retinas diagnosed with drusen and geographic atrophy in order to evaluate the performance of the described methods. PS-OCT appears as a promising imaging modality for three-dimensional retinal imaging and ranging with additional contrast based on the structures' tissue-inherent polarization properties.

Baumann, Bernhard; Götzinger, Erich; Pircher, Michael; Sattmann, Harald; Schütze, Christopher; Schlanitz, Ferdinand; Ahlers, Christian; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K.

2010-11-01

338

Fully automated detection of diabetic macular edema and dry age-related macular degeneration from optical coherence tomography images  

PubMed Central

We present a novel fully automated algorithm for the detection of retinal diseases via optical coherence tomography (OCT) imaging. Our algorithm utilizes multiscale histograms of oriented gradient descriptors as feature vectors of a support vector machine based classifier. The spectral domain OCT data sets used for cross-validation consisted of volumetric scans acquired from 45 subjects: 15 normal subjects, 15 patients with dry age-related macular degeneration (AMD), and 15 patients with diabetic macular edema (DME). Our classifier correctly identified 100% of cases with AMD, 100% cases with DME, and 86.67% cases of normal subjects. This algorithm is a potentially impactful tool for the remote diagnosis of ophthalmic diseases. PMID:25360373

Srinivasan, Pratul P.; Kim, Leo A.; Mettu, Priyatham S.; Cousins, Scott W.; Comer, Grant M.; Izatt, Joseph A.; Farsiu, Sina

2014-01-01

339

Percutaneous cervical nucleoplasty in the treatment of cervical disc herniation  

PubMed Central

Percutaneous disc decompression procedures have been performed in the past. Various percutaneous techniques such as percutaneous discectomy, laser discectomy, and nucleoplasty have been successful. Our prospective study was directly to evaluate the results of percutaneous cervical nucleoplasty (PCN) surgery for cervical disc herniation, and illustrate the effectiveness of PCN in symptomatic patients who had cervical herniated discs. From July of 2002 to June of 2005, 126 consecutive patients with contained cervical disc herniations have presented at the authors’ clinic and treated by PCN. The patients’ gender distribution for PCN was 65 male, 61 female. The age of patients ranged from 34 to 66 years (mean 51.9 ± 10.2 years). The levels of involvement were 21 cases at C3–4, 30 cases at C4–5, 40 cases at C5–6, and 35 cases at C6–7. The clinical outcomes, pain reduction and the segment stability were all recorded during this study. A clinical outcome was quantified by the Macnab standard and using VAS. The angular displacement (AD) ?11° or horizontal displacement (HD) ?3 mm was considered to be radiographically unstable. In the results of this study, puncture of the needle into the disc space was accurately performed under X-ray guidance in all cases. There was one case where the Perc-D Spine Wand had broken in the disc space during the procedure. The partial Perc-D Spine Wand, which had broken in the disc space could not be removed by the percutaneous cervical discectomy and thus remained there. There were no recurrent cases or complications in our series. Macnab standard results were excellent in 62 cases, good in 41 cases and fair in 23 cases. The rate of excellent and good was 83.73%. The VAS scores demonstrated statistically significant improvement in PCN at the 2-week, 1, 3, 6, and 12-month follow-up visits when compared to preoperational values (P < 0.01). There were no cases of instability following the PCN procedure. There was no significant difference in stability either preoperatively or postoperatively (P > 0.05). Our findings confirm that PCN for the treatment of cervical disc herniation results in a good outcome without any tampering of the stability of the cervical spine. Hence, PCN as a procedure is safe, minimally invasive, less traumatic, requiring less time with an excellent clinical outcome. PCN should be performed for those patients who fail conservative medical management including medication, physical therapy, behavioral management, psychotherapy, and who are unwilling to undergo a more invasive technique such as spinal surgery. PMID:18830638

Li, Jian; Zhang, Zai-Heng

2008-01-01

340

Destruction of protoplanetary discs in the Orion Nebula Cluster  

NASA Astrophysics Data System (ADS)

We use numerical N-body simulations of the Orion Nebula Cluster (ONC) to investigate the destruction of protoplanetary discs by close stellar encounters and UV radiation from massive stars. The simulations model a cluster of 4000 stars and we consider separately cases in which the discs have fixed radii of 100 and 10au. In the former case, depending on a star's position and orbit in the cluster over 107yr, UV photoevaporation removes at least 0.01Msolar from its disc, and can remove up to 1Msolar. We find no dynamical models of the ONC consistent with the suggestion of Störzer and Hollenbach that the observed distribution and abundance of proplyds could be explained by a population of stars on radial orbits that spend relatively little time near ?1C Ori (the most massive star in the ONC). Instead, the observations require either massive discs (e.g. a typical initial disc mass of 0.4Msolar) or a very recent birth for ?1C Ori. When we consider the photoevaporation of the inner 10au of discs in the ONC, we find that planet formation would be hardly affected. Outside that region, planets would be prevented from forming in about half the systems, unless either the initial disc masses were very high (e.g. 0.4Msolar) or they formed quickly (in less than ~2Myr) and ?1C Ori has only very recently appeared. We also present statistics on the distribution of minimum stellar encounter separations. This peaks at 1000au, with only about 4 per cent of stars having had an encounter closer than 100au at the cluster's present age, and less than 10 per cent after 107yr. We conclude that stellar encounters are unlikely to play a significant role in destroying protoplanetary discs. In the absence of any disruption mechanism other than those considered here, we would thus predict planetary systems like our own to be common amongst stars forming in ONC-like environments. Also, although almost all stars will have experienced an encounter at the radius of the Oort cloud in our own system, this only places a firm constraint on the possible birthplace of the Sun if the Oort cloud formed in situ, rather than through the secular ejection of matter from the planetary zone.

Scally, Aylwyn; Clarke, Cathie

2001-08-01

341

A Biphasic Finite Element Model of In   Vitro Plowing Tests of the Temporomandibular Joint Disc  

Microsoft Academic Search

Disorders of the temporomandibular joint (TMJ) afflict 3–29% of people aged 19–40 years. Degenerative joint disease (DJD)\\u000a of the TMJ generally occurs 15 years earlier than in other human joints and 1.5–2 times more often in women than men. The\\u000a TMJ disc is the primary stress distribution mechanism within the joint. Mechanical failure of the TMJ disc precedes clinical\\u000a signs of DJD.

R. L. Spilker; J. C. Nickel; L. R. Iwasaki

2009-01-01

342

MSC response to pH levels found in degenerating intervertebral discs  

Microsoft Academic Search

Painful degenerative disc disease is a major health problem and for successful tissue regeneration, MSCs must endure and thrive in a harsh disc microenvironment that includes matrix acidity as a critical factor. MSCs were isolated from bone marrow of Sprague–Dawley rats from two different age groups (<1 month, n=6 and 4–5 months, n=6) and cultured under four different pH conditions

Karin Wuertz; Karolyn Godburn; James C. Iatridis

2009-01-01

343

Long-term evolution, X-ray outburst and optical/infrared emission of SGR 0501+4516  

NASA Astrophysics Data System (ADS)

We have analysed the long-term evolution and the X-ray outburst light curve of SGR 0501+4516 in the fallback disc model. We have shown that the X-ray luminosity, period and period derivative of this typical soft gamma repeater can be achieved by a neutron star with a large range of initial disc masses provided that the source has a magnetic dipole field of ˜1.4 × 1012 G on the pole of the star. At present, the star is accreting matter from the disc, which has an age ˜3 × 104 yr, and will remain in the accretion phase until t ˜2-5 × 105 yr depending on the initial disc mass. With its current rotational rate, this source is not expected to give pulsed radio emission even if the accretion on to the star is hindered by some mechanism. The X-ray enhancement light curve of SGR 0501+4516 can be accounted for by the same model applied earlier to the X-ray enhancement light curves of other anomalous X-ray pulsars/soft gamma repeaters with the same basic disc parameters. We have further shown that the optical/infrared data of SGR 0501+4516 are in good agreement with the emission from an irradiated fallback disc with the properties consistent with our long-term evolution model.

Benli, O.; ?Çal??kan, ?.; Ertan, Ü.

2015-03-01

344

Three-dimensional spectral domain optical coherence tomography in X linked foveal retinoschisis  

PubMed Central

Spectral domain optical coherence tomography (SD-OCT) was performed in two cases of bilateral X linked foveal retinoschisis of different age groups. On fundus examination spoke wheel and honeycomb pattern of cysts were observed along with retinal nerve fibre layer (RNFL) defects. On SD-OCT, schisis was observed in the outer plexiform layer. External limiting membrane disruption was observed in the subfoveal area, along with disruption of outer nuclear layer (ONL) and inner–outer segment junction. Elevation of ONL due to tractional pull of central palisade was a novel observation. Retinoschisis extended beyond the optic disc up to the nasal region. Extracted RNFL tomogram presented an unprecedented visualisation of schisis along 360° of the optic disc. Tractional elevation in the foveal area and schisis involving nasal region, not observed upon clinical examination, was highlighted on SD-OCT. This investigative modality is an important adjunct in the assessment of foveal retinoschisis. PMID:23563673

Saxena, Sandeep; Manisha; Meyer, Carsten H

2013-01-01

345

The clinical study of percutaneous disc decompression of treating herniation of cervical disc with Nd:YAG laser  

NASA Astrophysics Data System (ADS)

Objective: The possibility of PLDD (percutaneous laser disc decompression) and an ideal non-operative method which is long everlasting effect for PLDD was investigated. Methods: 159 patients of Cervical Disc Herniation with PLDD were studied. All the herniated discs were irradiated with 10­15J/S Nd:YAG laser quantum through optical-fiber under the supervision of C-arm X-ray. Results: All the patients were followed and reexamined CT or MRI after one to six months of PLDD. The result of cured (67.92%), excellent (24.53%), moderation (5.66%), non-effect (1.88%) was got. The excellent rate was 88.24%. The effective rate was 97.65%. Non-effective rate was 2.35%. Conclusion: When irradiated with Nd:YAG laser, the nucleus pulposus was vapouring, charring and coagulating. The volume and inner-pressure of the disc decreased. So the symptoms and signs improved. The main value of this methods were micro-damage, non-operation, no bleeding, no bone injury, good therapy effect, quick recovery, lesser pain, safety and excellent long everlasting effect. It is an ideal non-operative method of treating PLDD.

Zhang, Dianxue; Cheng, Hefu; Wang, Jindong

2005-07-01

346

Association between apparent diffusion coefficient and intervertebral disc degeneration in patients with ankylosing spondylitis  

PubMed Central

Purpose: To assess the relation between ankylosing spondylitis (AS) and degenerative disc disease emerging in association with various intrinsic and extrinsic factors and to evaluate the correlation between degree of degeneration in intervertebral discs and apparent diffusion coefficient (ADC) values. Methods: Thirty-five patients with AS and a control group of 35 patients were included in the study. Three hundred fifty intervertebral discs were assessed in terms of degeneration by analyzing signal intensities and morphologies on T2 weighted series of a 1.5 Tesla magnetic resonance scanner. ADC values were determined in diffusion weighted images (DWI) using a “b value of 500 s/mm2”. Patients in the AS and control groups were compared in terms of intervertebral disc degeneration, and association between degree of degeneration and ADC values was analyzed. Results: The mean of total degeneration degrees for five lumbar intervertebral discs was significantly higher in the patients with AS compared to the control group (16.77±4.67 vs 13.00±4.08, respectively; P=0.001). When intervertebral discs were analyzed separately, disc degeneration was again significantly higher in patients with AS compared to the control group, with the exception of L5-S1. Age, cholesterol level, triglyceride level, duration of disease and BASFI index were significantly associated with degree of degeneration in patients with AS. A negative correlation was determined between disc degeneration and ADC value. Conclusion: AS is a risk factor for degenerative disc disease due to its systemic effects, the fact it leads to posture impairment and its inflammatory effects on the vertebrae. A decrease in ADC values is observed as degeneration worsens in degenerative disc disease. PMID:25785119

Resorlu, Mustafa; Gokmen, Ferhat; Resorlu, Hatice; Adam, Gurhan; Akbal, Ayla; Cevizci, Sibel; Sariyildirim, Abdullah; Savas, Yilmaz; Guven, Mustafa; Aras, Adem Bozkurt

2015-01-01

347

Relationship between physical work load and lumbar disc herniation.  

PubMed

Lumbar disc herniation (LDH) is a disabling problem. This retrospective case control study was done to evaluate the possible relevance of physical work load with Lumbar Disc Herniation. We have performed this study in the Spinal Surgery Unit of Department of Orthopaedic Surgery at BSMMU, Dhaka from July 2007 to June 2010 where 200 cases with Lumbar Disc Herniation and 200 control subjects matched by age, gender and area of residence were taken and analyzed. Chi-square test was computed for sex, area of residence, type of physical work and effort at work, whereas Odds ratio was computed for physical work load, stress at work and daily working period. The highest odds ratio (OR) was with the physical work load (OR: 03.48, CI: 01.84-06.59), hard work (OR: 03.14, CI: 01.74-05.65) and working period of >8 hours (OR: 01.34, CI: 0.75-02.38). Odds ratio for heavy load carrying at work was 03.48 and less job satisfaction or stress at work was 02.45. There was a statistically significant positive association between cumulative exposure of physical work load and lumbar disc herniation indicating an increased occurrence of herniation in heavy physical work load and occupation requiring harder efforts. PMID:23982545

Ahsan, M K; Matin, T; Ali, M I; Ali, M Y; Awwal, M A; Sakeb, N

2013-07-01

348

Kineflex (Centurion) Lumbar Disc Prosthesis: Insertion Technique and 2-Year Clinical Results in 100 Patients  

PubMed Central

Background The Kineflex lumbar disc is a mechanical, unconstrained, re-centering disc prosthesis developed in South Africa. The first implantation took place in October 2002. We present a single-center, prospective, longitudinal study of the first 100 patients treated with the Kineflex lumbar disc. Our objective was to evaluate the insertion technique, clinical outcomes, and patient satisfaction at 2 years postimplantation in 100 consecutive patients with 132 (68 single- and 32 2-level) Kineflex lumbar disc replacements. Methods We determined the exact central placement of all disc implants in the coronal and midsagittal planes. We measured clinical outcome with the Oswestry disability index (ODI), our own questionnaire, and the time needed to return to work. All patients received radiological and clinical follow-up assessments for 2 years after the index procedure. Results Forty-three patients were female. The mean age of the patients at operation was 44.9 years (range, 23–63 years). Postoperative hospitalization averaged 2.8 days (range, 2 to 8 days). All patients who were employed before surgery returned to work 31 ± 16.8 days after the operation. Fifty-six percent of operated disc levels had intervertebral disc heights of less than 5 mm. A 2-year clinical outcome was available for 98 of the 100 patients (58 excellent, 30 good, 7 fair, 3 poor). The ODI score improved from 47.8 ± 16.0 preoperatively to 14.2 ± 14.0 (P < .01) at 2 years. At 2 years, 95% of disc implants were radiologically in the ideal position. The insertion technique, with a released prosthetic mechanism for final placement, allowed ideal placement in the sagittal plane in 98% of discs. The radiographic placement accuracy achieved was equal in patients with preoperative intervertebral disc height below and above 5 mm. Conclusions Good short-term clinical results were achieved with the Kineflex disc in a heterogeneous patient group with a high number of patients with advanced disc degeneration, severe disc space narrowing, and lumbar flat-back deformity. In this cohort, accurate implant placement could be achieved in our first 100 patients. Clinical Relevence This is the first report on the Kineflex mechanical lumbar disc prosthesis.

Weinberg, Ian R.; Sliwa, Karen; Sweet, Barry MBE; de Villiers, Malan

2007-01-01

349

Factors regulating viable cell density in the intervertebral disc: blood supply in relation to disc height  

PubMed Central

The intervertebral disc is an avascular tissue, maintained by a small population of cells that obtain nutrients mainly by diffusion from capillaries at the disc–vertebral body interface. Loss of this nutrient supply is thought to lead to disc degeneration, but how nutrient supply influences viable cell density is unclear. We investigated two factors that influence nutrient delivery to disc cells and hence cell viability: disc height and blood supply. We used bovine caudal discs as our model as these show a gradation in disc height. We found that although disc height varied twofold from the largest to the smallest disc studied, it had no significant effect on cell density, unlike the situation found in articular cartilage. The density of blood vessels supplying the discs was markedly greater for the largest disc than the smallest disc, as was the density of pores allowing capillary penetration through the bony endplate. Results indicate that changes in blood vessels in the vertebral bodies supplying the disc, as well as changes in endplate architecture appear to influence density of cells in intervertebral discs. PMID:23311982

Boubriak, Olga A; Watson, Natasha; Sivan, Sarit S; Stubbens, Naomi; Urban, Jill P G

2013-01-01

350

Degenerative disc disease of herniated intervertebral discs is associated with extracellular matrix remodeling, vimentin-positive cells and cell death.  

PubMed

We studied patients with degenerative disc disease (DDD) to demonstrate that i) remodeling of the extracellular matrix (ECM) in the intervertebral disc (IVD), particularly the elastic fiber system, of subjects with herniated discs is dysregulated and that ii) it is accompanied by accelerated elastin degradation due to increased expression of matrix metalloprotease-9 (MMP-9). Moreover we wanted to obtain a deeper insight into the pathogenesis of DDD through the study of ECM calcification, DNA fragmentation using TUNEL analysis, BAX, bcl-2 and vimentin immunopositive cells. We studied herniated discs from patients of three age groups (group 1=30-40 years; group 2=40-50 years; and group 3=50-65 years) to evaluate the oxytalan fiber systemMMP-9, apoptosis and vimentin immunopositive cells. The results demonstrated the presence of oxytalan fibers in the annulus fibrosus (AF) and the nucleus pulposus (NP) of herniated discs. In the AF oxytalan fibers replaced disrupted mature elastic fibers in calcified areas, while in the NP they were mostly found in nests at the periphery of chondrocytes. MMP-9 was prevalently observed in NP nests above all in group 1 and group 3 discs while group 2 exhibited a lower MMP-9 immunostaining. Activation of the apoptotic process was demonstrated by upregulated BAX expression in group 3. BAX immunopositivity was inversely mirrored by a significant decrease in bcl-2 expression. Intermediate filament protein vimentin was strongly expressed only in group 1 samples. A large number of apoptotic TUNEL+ cells was observed in group 3 specimens. The presence of oxytalan fibers may be the result of a process of incomplete elastogenesis, or a response to mechanical stress trying to functionally replace the lack of elastic fibers. MMP-9 expression seems to relate to disc damage, while chondrocyte BAX upregulation and TUNEL+ cell staining revealed apoptosis activation regardless of patient age. Vimentin immunopositivity was clearly detected in group 1 annulus fibrosus and nucleus pulposus cells. In conclusion, as demonstrated by the vimentin-positive cells, the injured IVD has endogenous resources that can stem the DDD damage, including substitution of damaged elastic fibers by oxytalan fibers. In addition, induction of apoptosis suggests an increased cell turnover in response to repair needs. PMID:21330123

Loreto, Carla; Musumeci, Giuseppe; Castorina, Alessandro; Loreto, Corrado; Martinez, Giuseppa

2011-03-01

351

On the age vs depth and optical clarity of deep ice at South Pole  

E-print Network

The first four strings of phototubes for the AMANDA high-energy neutrino observatory are now frozen in place at a depth of 800 to 1000 m in ice at the South Pole. During the 1995-96 season an additional six strings will be deployed at greater depths. Provided absorption, scattering, and refraction of visible light are sufficiently small, the trajectory of a muon into which a neutrino converts can be determined by using the array of phototubes to measure the arrival times of \\v{C}erenkov light emitted by the muon. To help in deciding on the depth for implantation of the six new strings, we discuss models of age vs depth for South Pole ice, we estimate mean free paths for scattering from bubbles and dust as a function of depth, and we assess distortion of light paths due to refraction at crystal boundaries and interfaces between air-hydrate inclusions and normal ice. We conclude that the depth interval 1600 to 1800 m will be suitably transparent for the next six AMANDA strings and, moreover, that the interval 1600 to 2100 m will be suitably transparent for a future 1-km$^3$ observatory except possibly in a region a few tens of meters thick at a depth corresponding to a peak in the dust concentration at 60 kyr BP.

The AMANDA collaboration

1995-01-23

352

[Innervation of the intervertebral disc].  

PubMed

Until very recently, intervertebral disc innervation was a subject of considerable debate. Nowadays, the introduction of inmunohistochemical techniques associated to specific antibodies and studies with retrograde tracers in nerves have allowed greater understanding of disc innervation in physiological and pathological conditions and also endings characteristics and their patterns of distribution in both situations. The existing controversies regarding structural basis of discogenic pain, have raised the interest of knowing the influence of innervation in back pain from discal origin and its characteristics. Today, we know that pathologic neoinnervation accompanying radial fissures is an important factor in the genesis of discogenic pain; within a complex mechanism in which other neurobiomechemical, inflammatory and biomechanical factors are involved. PMID:23582224

García-Cosamalón, José; Fernández-Fernández, Javier; González-Martínez, Emilio; Ibáñez-Plágaro, Javier; Robla Costales, Javier; Martínez-Madrigal, Milton; López Muñíz, Alfonso; del Valle, Miguel Enrique; Vega, José Antonio

2013-01-01

353

Thermal cracking in disc brakes  

Microsoft Academic Search

Disc brakes are exposed to large thermal stresses during routine braking and extraordinary thermal stresses during hard braking. High-g decelerations typical of passenger vehicles are known to generate temperatures as high as 900°C in a fraction of a second. These large temperature excursions have two possible outcomes: thermal shock that generates surface cracks; and\\/or large amounts of plastic deformation in

Thomas J. Mackin; Steven C. Noe; K. J. Ball; B. C. Bedell; D. P. Bim-Merle; M. C. Bingaman; D. M. Bomleny; G. J. Chemlir; D. B. Clayton; H. A. Evans; R. Gau; J. L. Hart; J. S. Karney; B. P. Kiple; R. C. Kaluga; P. Kung; A. K. Law; D. Lim; R. C. Merema; B. M. Miller; T. R. Miller; T. J. Nielson; T. M. O'Shea; M. T. Olson; H. A. Padilla; B. W. Penner; C. Penny; R. P. Peterson; V. C. Polidoro; A. Raghu; B. R. Resor; B. J. Robinson; D. Schambach; B. D. Snyder; E. Tom; R. R. Tschantz; B. M. Walker; K. E. Wasielewski; T. R. Webb; S. A. Wise; R. S. Yang; R. S. Zimmerman

2002-01-01

354

Hydrodynamic instability in eccentric astrophysical discs  

NASA Astrophysics Data System (ADS)

Eccentric Keplerian discs are believed to be unstable to three-dimensional hydrodynamical instabilities driven by the time-dependence of fluid properties around an orbit. These instabilities could lead to small-scale turbulence, and ultimately modify the global disc properties. We use a local model of an eccentric disc, derived in a companion paper, to compute the non-linear vertical (`breathing mode') oscillations of the disc. We then analyse their linear stability to locally axisymmetric disturbances for any disc eccentricity and eccentricity gradient using a numerical Floquet method. In the limit of small departures from a circular reference orbit, the instability of an isothermal disc is explained analytically. We also study analytically the small-scale instability of an eccentric neutrally stratified polytropic disc with any polytropic index using a Wentzel-Kramers-Brillouin (WKB) approximation. We find that eccentric discs are generically unstable to the parametric excitation of small-scale inertial waves. The non-linear evolution of these instabilities should be studied in numerical simulations, where we expect them to lead to a decay of the disc eccentricity and eccentricity gradient as well as to induce additional transport and mixing. Our results highlight that it is essential to consider the three-dimensional structure of eccentric discs, and their resulting vertical oscillatory flows, in order to correctly capture their evolution.

Barker, A. J.; Ogilvie, G. I.

2014-12-01

355

Irradiated, colour-temperature-corrected accretion discs in ultraluminous X-ray sources  

NASA Astrophysics Data System (ADS)

Although attempts have been made to constrain the stellar types of optical counterparts to ultraluminous X-ray sources (ULXs), the detection of optical variability instead suggests that they may be dominated by reprocessed emission from X-rays which irradiate the outer accretion disc. Here, we report results from a combined X-ray and optical spectral study of a sample of ULXs, which were selected for having broadened disc-like X-ray spectra and known optical counterparts. We simultaneously fit optical and X-ray data from ULXs with a new spectral model of emission from an irradiated, colour-temperature-corrected accretion disc around a black hole, with a central Comptonizing corona. We find that the ULXs require reprocessing fractions of ˜10-3, which is similar to sub-Eddington thermal dominant state black hole binaries (BHBs), but less than has been reported for ULXs with soft ultraluminous X-ray spectra. We suggest that the reprocessing fraction may be due to the opposing effects of self-shielding in a geometrically thick supercritical accretion disc and reflection from far above the central black hole by optically thin material ejected in a natal super-Eddington wind. Then, the higher reprocessing fractions reported for ULXs with wind-dominated X-ray spectra may be due to enhanced scattering on to the outer disc via the stronger wind in these objects. Alternatively, the accretion discs in these ULXs may not be particularly geometrically thick, rather they may be similar in this regard to the thermal dominant state BHBs.

Sutton, Andrew D.; Done, Chris; Roberts, Timothy P.

2014-11-01

356

Magnetic jets from swirling discs  

NASA Astrophysics Data System (ADS)

A broad swathe of astrophysical phenomena, ranging from tubular planetary nebulae through Herbig-Haro objects, radio galaxy and quasar emissions to gamma-ray bursts and perhaps high-energy cosmic rays, may be driven by magnetically dominated jets emanating from accretion discs. We give a self-contained account of the analytic theory of non-relativistic magnetically dominated jets wound up by a swirling disc and making a magnetic cavity in a background medium of any prescribed pressure, p(z). We solve the time-dependent problem for any specified distribution of magnetic flux P(R, 0) emerging from the disc at z = 0, with any specified disc angular velocity ?d(R). The physics required to do this involves only the freezing of the lines of force to the conducting medium and the principle of minimum energy. In a constant pressure environment, the magnetically dominated cavity is highly collimated and advances along the axis at a constant speed closely related to the maximum circular velocity of the accretion disc. Even within the cavity the field is strongly concentrated towards the axis. The twist in the jet field /<|Bz|> is close to and the width of the jet decreases upwards. By contrast, when the background pressure falls off with height with powers approaching z-4, the head of the jet accelerates strongly and the twist of the jet is much smaller. The width increases to give an almost conical magnetic cavity with apex at the source. Such a regime may be responsible for some of the longest strongly collimated jets. When the background pressure falls off faster than z-4, there are no quasi-static configurations of well-twisted fields and the pressure confinement is replaced by a dynamic effective pressure or a relativistic expansion. In the regimes with rapid acceleration, the outgoing and incoming fields linking the twist back to the source are almost anti-parallel so there is a possibility that magnetic reconnections may break up the jet into a series of magnetic `smoke-rings' travelling out along the axis.

Lynden-Bell, D.

2006-07-01

357

Intervertebral disc viscoelastic parameters and residual mechanics spatially quantified using a hybrid confined/in situ indentation method.  

PubMed

With advancing age, injury, musculoskeletal pathology or a combination of these, a degenerative cascade of biomechanical, biochemical, and nutritional alterations diminish the intervertebral discs' ability to maintain its structure and function. While the biomechanics of isolated disc tissues has been investigated across this degenerative spectrum, none have attempted to retain the in situ disc-endplate morphology during compressive tissue characterization. The objective of this study was to spatially quantify the viscoelastic parameters of the intervertebral disc throughout degeneration, including the as yet unreported residual stress/strain. This required the development of a hybrid confined/in situ indentation methodology, which preserves the disc structural morphology. At four locations of the disc (anterior-AF, right and left lateral AF, and NP) stress-relaxation tests were performed using the hybrid confined/in situ indentation method, which utilizes the vertebral endplate as the porous indenter tip. This method allows the endplate to remain interwoven with the disc tissue, retaining its native orientation. Healthy disc tissue exhibited significantly higher residual stress values compared to both moderate and severe degeneration in all locations (p<0.0156). Furthermore, the equilibrium stress at 15% strain (stress relaxation) was significantly diminished with advancing disc degeneration (p<0.0241). The equilibrium viscoelastic parameters show healthy discs encounter higher forces at the same strain level, and are able to maintain this force, where degenerated discs are unable to maintain this force throughout time. This morphology-conserved method provides insight into the spatial compressive mechanical properties of the intervertebral disc across the degeneration spectrum and will aid in modeling these tissue changes. PMID:22197186

Ellingson, Arin M; Nuckley, David J

2012-02-01

358

Resolved debris discs around A stars in the Herschel DEBRIS survey  

NASA Astrophysics Data System (ADS)

The majority of debris discs discovered so far have only been detected through infrared excess emission above stellar photospheres. While disc properties can be inferred from unresolved photometry alone under various assumptions for the physical properties of dust grains, there is a degeneracy between disc radius and dust temperature that depends on the grain size distribution and optical properties. By resolving the disc we can measure the actual location of the dust. The launch of Herschel, with an angular resolution superior to previous far-infrared telescopes, allows us to spatially resolve more discs and locate the dust directly. Here we present the nine resolved discs around A stars between 20 and 40 pc observed by the Disc Emission via a Bias-free Reconnaissance in the Infrared/Submillimetre (DEBRIS) survey. We use these data to investigate the disc radii by fitting narrow ring models to images at 70, 100 and 160 ?m and by fitting blackbodies to full spectral energy distributions. We do this with the aim of finding an improved way of estimating disc radii for unresolved systems. The ratio between the resolved and blackbody radii varies between 1 and 2.5. This ratio is inversely correlated with luminosity and any remaining discrepancies are most likely explained by differences to the minimum size of grain in the size distribution or differences in composition. We find that three of the systems are well fit by a narrow ring, two systems are borderline cases and the other four likely require wider or multiple rings to fully explain the observations, reflecting the diversity of planetary systems.

Booth, Mark; Kennedy, Grant; Sibthorpe, Bruce; Matthews, Brenda C.; Wyatt, Mark C.; Duchêne, Gaspard; Kavelaars, J. J.; Rodriguez, David; Greaves, Jane S.; Koning, Alice; Vican, Laura; Rieke, George H.; Su, Kate Y. L.; Moro-Martín, Amaya; Kalas, Paul

2013-01-01

359

A disc inside the bipolar planetary nebula M2-9  

NASA Astrophysics Data System (ADS)

Aims: Bipolarity in proto-planetary and planetary nebulae is associated with events occurring in or around their cores. Past infrared observations have revealed the presence of dusty structures around the cores, many in the form of discs. Characterising those dusty discs provides invaluable constraints on the physical processes that govern the final mass expulsion of intermediate mass stars. We focus this study on the famous M2-9 bipolar nebula, where the moving lighthouse beam pattern indicates the presence of a wide binary. The compact and dense dusty core in the centre of the nebula can be studied by means of optical interferometry. Methods: M2-9 was observed with VLTI/MIDI at 39-47 m baselines with the UT2-UT3 and UT3-UT4 baseline configurations. These observations are interpreted using a dust radiative transfer Monte Carlo code. Results: A disc-like structure is detected perpendicular to the lobes, and a good fit is found with a stratified disc model composed of amorphous silicates. The disc is compact, 25 × 35 mas at 8 ?m and 37 × 46 mas at 13 ?m. For the adopted distance of 1.2 kpc, the inner rim of the disc is ~15 AU. The mass represents a few percent of the mass found in the lobes. The compactness of the disc puts strong constraints on the binary content of the system, given an estimated orbital period 90-120 yr. We derive masses of the binary components between 0.6-1.0 M? for a white dwarf and 0.6-1.4 M? for an evolved star. We present different scenarios on the geometric structure of the disc accounting for the interactions of the binary system, which includes an accretion disc as well. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, ESO N: 079.D-146.

Lykou, F.; Chesneau, O.; Zijlstra, A. A.; Castro-Carrizo, A.; Lagadec, E.; Balick, B.; Smith, N.

2011-03-01

360

On the warping of Be star discs  

E-print Network

The theory of radiatively-induced warps in accretion discs is applied to the discs of Be stars. It is found that these discs may develop warps in their inner regions, although once the warp amplitude is large enough then the interaction between the disc and fast radiatively-driven wind will determine its evolution. The warping is shown to be more important for later than earlier B stars. Although the interaction of the fast-wind with the disc will limit the amplitude of the warp, it cannot drive the warp radially outwards, and so the radial evolution of the warp depends on the dominant advective process within the disc. Typical timescales associated with growing modes are shown to be short, of the order of days-weeks, although these are not likely to be the timescales inferred from observations of line-profile variations which are much longer, of the order of years.

John M. Porter

1998-05-26

361

Spectral Domain Optical Coherence Tomography in Glaucoma: Qualitative and Quantitative Analysis of the Optic Nerve Head and Retinal Nerve Fiber Layer (An AOS Thesis)  

PubMed Central

Purpose: To demonstrate that video-rate spectral domain optical coherence tomography (SDOCT) can qualitatively and quantitatively evaluate optic nerve head (ONH) and retinal nerve fiber layer (RNFL) glaucomatous structural changes. To correlate quantitative SDOCT parameters with disc photography and visual fields. Methods: SDOCT images from 4 glaucoma eyes (4 patients) with varying stages of open-angle glaucoma (ie, early, moderate, late) were qualitatively contrasted with 2 age-matched normal eyes (2 patients). Of 61 other consecutive patients recruited in an institutional setting, 53 eyes (33 patients) met inclusion/exclusion criteria for quantitative studies. Images were obtained using two experimental SDOCT systems, one utilizing a superluminescent diode and the other a titanium:sapphire laser source, with axial resolutions of about 6 ?m and 3 ?m, respectively. Results: Classic glaucomatous ONH and RNFL structural changes were seen in SDOCT images. An SDOCT reference plane 139 ?m above the retinal pigment epithelium yielded cup-disc ratios that best correlated with masked physician disc photography cup-disc ratio assessments. The minimum distance band, a novel SDOCT neuroretinal rim parameter, showed good correlation with physician cup-disc ratio assessments, visual field mean deviation, and pattern standard deviation (P values range, .0003–.024). RNFL and retinal thickness maps correlated well with disc photography and visual field testing. Conclusions: To our knowledge, this thesis presents the first comprehensive qualitative and quantitative evaluation of SDOCT images of the ONH and RNFL in glaucoma. This pilot study provides basis for developing more automated quantitative SDOCT-specific glaucoma algorithms needed for future prospective multicenter national trials. PMID:20126502

Chen, Teresa C.

2009-01-01

362

Close-packing of growing discs  

SciTech Connect

Spiral lattices are derived by allowing growing discs to aggregate under a close-packing rule. Both Fibonacci and Lucas numbers of visible spirals arise naturally, dependent only on the choice of growth centre. Both the rate of convergence towards an ideal spiral, and chirality, are determined by the initial placement of the first few discs (initial conditions). Thus the appearance of spiral packings is no more or less mysterious than the appearance of hexagonal packed arrays of equal discs.

Bursill, L.A.; Xudong, F. (Melbourne Univ., Parkville (Australia). School of Physics)

1988-12-01

363

Capillary hemangioma of the cervical intervertebral disc  

Microsoft Academic Search

An anterior cervical decompression and fusion operation was complicated by extensive bleeding from the disc space. Histopathological\\u000a evaluation of the resected specimen revealed the diagnosis as the very first reported case of capillary hemangioma in intervertebral\\u000a disc space. Retrospective review of the preoperative MRI demonstrated supporting findings of a capillary hemangioma within\\u000a the cervical intervertebral disc.

Ahmet Cetinkal; Ahmet Colak; Kivanc Topuz; Cem Atabey; Ufuk Berber

2011-01-01

364

Stirring in massive, young debris discs from spatially resolved Herschel images  

NASA Astrophysics Data System (ADS)

A significant fraction of main-sequence stars are encircled by dusty debris discs, where the short-lived dust particles are replenished through collisions between planetesimals. Most destructive collisions occur when the orbits of smaller bodies are dynamically stirred up, either by the gravitational effect of locally formed Pluto-sized planetesimals (self-stirring scenario), or via secular perturbation caused by an inner giant planet (planetary stirring). The relative importance of these scenarios in debris systems is unknown. Here, we present new Herschel Space Observatory imagery of 11 discs selected from the most massive and extended known debris systems. All discs were found to be extended at far-infrared wavelengths, five of them being resolved for the first time. We evaluated the feasibility of the self-stirring scenario by comparing the measured disc sizes with the predictions of the model calculated for the ages of our targets. We concluded that the self-stirring explanation works for seven discs. However, in four cases, the predicted pace of outward propagation of the stirring front, assuming reasonable initial disc masses, was far too low to explain the radial extent of the cold dust. Therefore, for HD 9672, HD 16743, HD 21997, and HD 95086, another explanation is needed. We performed a similar analysis for ? Pic and HR 8799, reaching the same conclusion. We argue that planetary stirring is a promising possibility to explain the disc properties in these systems. In HR 8799 and HD 95086, we may already know the potential perturber, since their known outer giant planets could be responsible for the stirring process. Interestingly, the discs around HD 9672, HD 21997, and ? Pic are also unique in harbouring detectable amount of molecular CO gas. Our study demonstrates that among the largest and most massive debris discs self-stirring may not be the only active scenario, and potentially planetary stirring is responsible for destructive collisions and debris dust production in a number of systems.

Moór, A.; Kóspál, Á.; Ábrahám, P.; Apai, D.; Balog, Z.; Grady, C.; Henning, Th.; Juhász, A.; Kiss, Cs.; Krivov, A. V.; Pawellek, N.; Szabó, Gy. M.

2015-02-01

365

On the evolution of the protolunar disc.  

PubMed

The structure and viscous evolution of a post-impact, protolunar disc is examined. The equations for a silicate disc in two-phase (vapour-liquid) equilibrium are employed to derive an analytical solution to vertical structure. Both a vertically mixed phase disc and a stratified disc, where a magma layer exists in the mid-plane surrounded by a vapour reservoir, are considered. The former largely reproduces the low gas mass fraction, x?1, profiles of the disc described in earlier literature that proposed that the disc would hover on the brink of gravitational instability. In the latter, the vapour layer has x?1 and is generally gravitationally stable, while the magma layer is vigorously unstable. The viscous evolution of the stratified model is then explored. Initially, the disc quickly settles to a quasi-steady state with a vapour reservoir containing the majority of the disc mass. The magma layer viscously spreads on a time scale of approximately 3-4 years, during which vapour continuously condenses into droplets that settle to the mid-plane, maintaining the magma surface density in spite of disc spreading. Material flowing inwards is accreted by the Earth; material flowing outwards past the Roche boundary can become incorporated into accreting moonlets. This evolution persists until the vapour reservoir is depleted in approximately 50-100 years, depending on its initial mass. PMID:25114314

Ward, William R

2014-09-13

366

Compact Optical Module of Homodyne Detection  

NASA Astrophysics Data System (ADS)

Homodyne detection is a detection technique that significantly amplifies optical signals. It is useful for the readout of multilayer optical discs, where the signal level is quite low. The improvement of optical disc readout signal quality by homodyne detection has been demonstrated experimentally. However, homodyne detection requires a complicated optical system, which causes large-scale implementation and high cost, which prevents practical use of the technique in optical disc systems. In this report, we demonstrated compact implementation of homodyne detection. We proposed and assembled two types of optical module for homodyne detection. The sizes of the modules were 10×30 and 10×40 mm2, which were comparable to that of the current optical pickup. Jitter of the attenuated Blu-ray DiscTM recordable (BD-R) readout signals was improved from 15 to 7.8% by applying one of the modules.

Mikami, Hideharu; Kurokawa, Takahiro; Watanabe, Koichi

2012-08-01

367

Optical ages indicate the southwestern margin of the Green Bay Lobe in Wisconsin, USA, was at its maximum extent until about 18,500 years ago  

USGS Publications Warehouse

Samples for optical dating were collected to estimate the time of sediment deposition in small ice-marginal lakes in the Baraboo Hills of Wisconsin. These lakes formed high in the Baraboo Hills when drainage was blocked by the Green Bay Lobe when it was at or very near its maximum extent. Therefore, these optical ages provide control for the timing of the thinning and recession of the Green Bay Lobe from its maximum position. Sediment that accumulated in four small ice-marginal lakes was sampled and dated. Difficulties with field sampling and estimating dose rates made the interpretation of optical ages derived from samples from two of the lake basins problematic. Samples from the other two lake basins-South Bluff and Feltz basins-responded well during laboratory analysis and showed reasonably good agreement between the multiple ages produced at each site. These ages averaged 18.2. ka (n= 6) and 18.6. ka (n= 6), respectively. The optical ages from these two lake basins where we could carefully select sediment samples provide firm evidence that the Green Bay Lobe stood at or very near its maximum extent until about 18.5. ka.The persistence of ice-marginal lakes in these basins high in the Baraboo Hills indicates that the ice of the Green Bay Lobe had not experienced significant thinning near its margin prior to about 18.5. ka. These ages are the first to directly constrain the timing of the maximum extent of the Green Bay Lobe and the onset of deglaciation in the area for which the Wisconsin Glaciation was named. ?? 2011 Elsevier B.V.

Attig, J.W.; Hanson, P.R.; Rawling, J.E.; Young, A.R.; Carson, E.C.

2011-01-01

368

Large disc intermediate precedes formation of apolipoprotein A-I DMPC small discs  

PubMed Central

Small ~8.5 nm discs formed spontaneously when and dimyristoyl phosphatidylcholine (DMPC) large unilamellar vesicles (LUVs) were incubated with apolipoprotein A-I (apoA-I) (100:1 molar ratio). However, in a time course study, the transient production of ~11 nm large discs was detected and isolated by gel filtration. The intermediate large discs contained three apoA-I molecules and were stable over time; but, when additional apoA-I was added they formed small discs containing two molecules of apoA-I. The reaction kinetics of apoA-I with DMPC LUVs was monitored by fluorescence resonance energy transfer and two phases were observed, supporting the presence of the intermediate in the formation of small discs. The lipid dynamics of LUVs and discs were assayed revealing the presence of sequestered lipid-protein domains upon apoA-I binding to DMPC LUVs. In addition, the lipids in the intermediate large discs were more constrained than those in the small discs. We propose that apoA-I binds with DMPC LUVs to form small lipid-protein domains on the LUV, then the domains are released to form large discs, which can mature in the presence of additional apoA-I to form small discs. Thus, the formation of small apoA-I lipid discs proceeds through the formation of a large disc intermediate. PMID:17474718

Zhu, Keng; Brubaker, Gregory; Smith, Jonathan D.

2008-01-01

369

Theory of Black Hole Accretion Discs  

NASA Astrophysics Data System (ADS)

Part I. Observations of Black Holes: 1. Black holes in our Galaxy: observations P. Charles; 2. Black holes in Active Galactic Nuclei: observations G. M. Madejski; Part II. Physics Close to a Black Hole: 3. Physics of black holes I. D. Novikov; 4. Physics of black hole accretion M. A. Abramowicz; Part III. Turbulence, Viscosity: 5. Disc turbulence and viscosity A. Brandenburg; Part IV. Radiative Processes: 6. The role of electron-positron pairs in accretion flows G. Björnsson; 7. Accretion disc-corona models and X/Y-ray spectra of accreting black holes J. Poutanen; 8. Emission lines: signatures of relativistic rotation A. C. Fabian; Part V. Accretion Discs: 9. Spectral tests of models for accretion disks around black holes J. H. Krolik; 10. Advection-dominated accretion around black holes R. Narayan, R. Mahadevan and E. Quataert; 11. Accretion disc instabilities and advection dominated accretion flows J.-P. Lasota; 12. Magnetic field and multi-phase gas in AGN A. Celotti and M. J. Rees; Part V. Discs in Binary Black Holes: 13. Supermassive binary black holes in galaxies P. Artymowicz; Part VI. Stability of Accretion Discs: 14. Large scale perturbation of an accretion disc by a black hole binary companion J. C. B. Papaloizou, C. Terquem and D. N. C. Lin; 15. Stable oscillations of black hole accretion discs M. Nowak and D. Lehr; Part VI. Coherant Structures: 16. Spotted discs A. Bracco, A. Provenzale, E. A. Spiegel and P. Yecko; Self-organized critically in accretion discs P. Wiita and Y. Xiong; Summary: old and new advances in black hole accretion disc theory R. Svensson.

Abramowicz, Marek A.; Björnsson, Gunnlaugur; Pringle, James E.

2010-08-01

370

Advanced Radial Position Control of a Recording Beam for Super Multilayer Disc with Separated Guide Layer  

NASA Astrophysics Data System (ADS)

We have developed an advanced radial position control system for a super multilayer disc with a separated guide layer to realize stable recording on the plane recording layers located far from the guide layer. The developed system consists of an advanced sled servo system and a specially designed optics based on the advanced push-pull method. Recorded signals on all recording layers were evaluated by using integrated-maximum likelihood sequence error estimation (i-MLSE) as the evaluation indicator. As a result, we confirmed sufficient recorded signal qualities and feasibility at the quad-speed continuous recording with a constant track pitch of 0.32 µm, the same as that of Blu-ray disc (BD). We believe that our proposed concept is the most practical solution for the next-generation optical disc system and our control system is essential to realize stable multilayer recording with a constant track pitch.

Tanaka, Hiroyuki; Takahashi, Kazuo; Ogasawara, Masakazu; Taniguchi, Shoji

2013-09-01

371

Optical absorption as a sensitive monitor of tensile strength loss in thermally aged nylon 6,6  

Microsoft Academic Search

Chemical changes which take place in polymers during thermal aging often adversely affect the bulk physical properties of the material. Aging rates under ambient conditions are usually so slow as to require extremely long aging cycles to achieve measurable losses in such properties as tensile strength. Therefore, accelerated aging under more stressful conditions (e.g., higher temperatures) with Arrhenius-plot extrapolations to

1985-01-01

372

The frequency and infrared brightness of circumstellar discs at white dwarfs  

NASA Astrophysics Data System (ADS)

White dwarfs whose atmospheres are polluted by terrestrial-like planetary debris have become a powerful and unique tool to study evolved planetary systems. This paper presents results for an unbiased Spitzer Infrared Array Camera search for circumstellar dust orbiting a homogeneous and well-defined sample of 134 single white dwarfs. The stars were selected without regard to atmospheric metal content but were chosen to have (1) hydrogen-rich atmospheres, (2) 17 000 < Teff < 25 000 K and correspondingly young post-main-sequence ages of 15-270 Myr, and (3) sufficient far-ultraviolet brightness for a corresponding Hubble Space Telescope COS snapshot. Five white dwarfs were found to host an infrared bright dust disc, three previously known, and two reported here for the first time, yielding a nominal 3.7^{+2.4}_{-1.0} per cent of white dwarfs in this post-main-sequence age range with detectable circumstellar dust. Remarkably, the complementary Hubble observations indicate that a fraction of 27 per cent show metals in their photosphere that can only be explained with ongoing accretion from circumstellar material, indicating that nearly 90 per cent of discs escape detection in the infrared, likely due to small emitting surface area. This paper also presents the distribution of disc fractional luminosity as a function of cooling age for all known dusty white dwarfs, suggesting possible disc evolution scenarios and indicating an undetected population of circumstellar discs.

Rocchetto, M.; Farihi, J.; Gänsicke, B. T.; Bergfors, C.

2015-05-01

373

Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings  

NASA Astrophysics Data System (ADS)

The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.

Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa

2004-09-01

374

Cervical arthroplasty using ProDisc-C case report.  

PubMed

Cervical disc replacement is an emerging motion-preserving technology in the surgical treatment of the cervical degenerative disc disorders used as an alternative to the classic interbody fusion. We present a case report of a patient diagnosed with C6-7 right disc herniation who underwent anterior discectomy and received a total disc replacement using ProDisc C artificial disc prosthesis. PMID:23599830

Nica, D A; Copaciu, R

2013-03-15

375

21 cm absorption by compact hydrogen discs around black holes in radio-loud nuclei of galaxies  

SciTech Connect

The clumpy maser discs observed in some galactic nuclei mark the outskirts of the accretion disc that fuels the central black hole and provide a potential site of nuclear star formation. Unfortunately, most of the gas in maser discs is currently not being probed; large maser gains favor paths that are characterized by a small velocity gradient and require rare edge-on orientations of the disc. Here we propose a method for mapping the atomic hydrogen distribution in nuclear discs through its 21 cm absorption against the radio continuum glow around the central black hole. In NGC 4258, the 21 cm optical depth may approach unity for high angular resolution (VLBI) imaging of coherent clumps which are dominated by thermal broadening and have the column density inferred from x-ray absorption data, {approx}10{sup 23} cm{sup -2}. Spreading the 21 cm absorption over the full rotation velocity width of the material in front of the narrow radio jets gives a mean optical depth of {approx}0.1. Spectroscopic searches for the 21 cm absorption feature in other galaxies can be used to identify the large population of inclined gaseous discs which are not masing in our direction. Follow-up imaging of 21 cm silhouettes of accelerating clumps within these discs can in turn be used to measure cosmological distances.

Loeb, Abraham, E-mail: aloeb@cfa.harvard.edu [Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)] [Astronomy Department, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)

2008-05-15

376

33.4 Gbyte/Layer Recording with Adaptive Write Strategy for 100 Gbyte Rewritable Triple-Layer Disc  

NASA Astrophysics Data System (ADS)

For multilayer rewritable optical discs, we developed a new adaptive write strategy named the S-22 (sequential 2T-2T) write pulse control method, which controls the laser pulse of the 2T-mark according to the combination of both the preceding and succeeding space lengths. By applying this write strategy, a rewritable triple-layer disc based on Blu-ray disc optical systems with a capacity of 100 Gbyte was realized. In particular, the advantage of this write strategy is significant for a transparent information layer. The bit shift of sequential 2T-2T patterns, which is a dominant error in 100 Gbyte rewritable discs, was well compensated. We experimentally confirmed that adopting the S-22 write pulse control method is effective to improve symbol error rate.

Nakamura, Atsushi; Kobayashi, Isao; Narumi, Kenji; Takaoka, Tomoyasu; Furumiya, Shigeru; Miyagawa, Naoyasu

2010-08-01

377

Intrinsically photosensitive retinal ganglion cell function in relation to age: A pupillometric study in humans with special reference to the age-related optic properties of the lens  

PubMed Central

Background The activity of melanopsin containing intrinsically photosensitive ganglion retinal cells (ipRGC) can be assessed by a means of pupil responses to bright blue (appr.480?nm) light. Due to age related factors in the eye, particularly, structural changes of the lens, less light reaches retina. The aim of this study was to examine how age and in vivo measured lens transmission of blue light might affect pupil light responses, in particular, mediated by the ipRGC. Methods Consensual pupil responses were explored in 44 healthy subjects aged between 26 and 68?years. A pupil response was recorded to a continuous 20?s light stimulus of 660?nm (red) or 470?nm (blue) both at 300?cd/m2 intensity (14.9 and 14.8 log photons/cm2/s, respectively). Additional recordings were performed using four 470?nm stimulus intensities of 3, 30, 100 and 300?cd/m2. The baseline pupil size was measured in darkness and results were adjusted for the baseline pupil and gender. The main outcome parameters were maximal and sustained pupil contraction amplitudes and the postillumination response assessed as area under the curve (AUC) over two time-windows: early (0–10?s after light termination) and late (10–30?s after light termination). Lens transmission was measured with an ocular fluorometer. Results The sustained pupil contraction and the early poststimulus AUC correlated positively with age (p?=?0.02, p?=?0.0014, respectively) for the blue light stimulus condition only. The maximal pupil contraction amplitude did not correlate to age either for bright blue or red light stimulus conditions. Lens transmission decreased linearly with age (p?Age did not reduce, but rather enhance pupil responses mediated by ipRGC. The age related decrease of blue light transmission led to similar results, however, the effect of age was greater on these pupil responses than that of the lens transmission. Thus there must be other age related factors such as lens scatter and/or adaptive processes influencing the ipRGC mediated pupil response enhancement observed with advancing age. PMID:22471313

2012-01-01

378

Are all young stars disc accretors?  

E-print Network

We now understand how low mass stars evolve through cloud collapse and disc accretion, but whether higher mass stars are also disc accretors is as yet unknown. Spectropolarimetry observations can help in answering this basic question, as they probe the first few stellar radii around young stars.

Jorick S. Vink; Janet E. Drew; Tim J. Harries; Rene D. Oudmaijer

2001-10-05

379

Transmural migration of gastrostomy tube retention discs  

Microsoft Academic Search

Background Accidental dislodgment is one of the most frequent causes of avoidable cost and consternation related to gastrostomy tubes. The Sacks–Vine gastrostomy tube, inserted in an antegrade fashion by a percutaneous technique, is extremely stable due to the construction of its disc retention device. However, transmural migration of the retention disc is a known severe delayed complication associated with this

AnneMarie Cahill; Kevin M. Baskin; Robin D. Kaye; Charles R. Fitz; Richard B. Towbin

2004-01-01

380

The tidal disruption of protoplanetary accretion discs  

E-print Network

In this paper we revisit the problem of the tidal interaction occuring between a protostellar accretion disc and a secondary point mass following a parabolic trajectory. We model the disc response analytically and we compare our results with three-dimensional SPH simulations. Inviscid as well as viscous hydrodynamics is considered. We show that in a viscous system the response derived from inviscid considerations is predominant even for the highest estimates of an anomalous disc shear viscosity. The angular momentum lost from the disc during the encounter is derived from linear theory, for distant fly-bys, as well as the changes to the disc orientation expected in non-coplanar encounters. It is shown that the target discs can become warped and precess by a small amount during non-coplanar encounters. This small precession is shown to give rise to a relative tilt of the disc which is always more important for determining its final orientation than is the change to the orbital inclination. We discuss the implications of our results for protostellar accretion discs and planetary systems.

John D. Larwood

1997-05-30

381

Quantitative Classification of Eyes with and without Intermediate Age-related Macular Degeneration Using Optical Coherence Tomography  

PubMed Central

Objective To define quantitative indicators for the presence of intermediate age-related macular degeneration (AMD) via spectral-domain optical coherence tomography (SD-OCT) imaging of older adults. Design Evaluation of diagnostic test and technology. Participants and Controls One eye from 115 elderly subjects without AMD and 269 subjects with intermediate AMD from the Age-Related Eye Disease Study 2 (AREDS2) Ancillary SD-OCT Study. Methods We semiautomatically delineated the retinal pigment epithelium (RPE) and RPE drusen complex (RPEDC, the axial distance from the apex of the drusen and RPE layer to Bruch's membrane) and total retina (TR, the axial distance between the inner limiting and Bruch's membranes) boundaries. We registered and averaged the thickness maps from control subjects to generate a map of “normal” non-AMD thickness. We considered RPEDC thicknesses larger or smaller than 3 standard deviations from the mean as abnormal, indicating drusen or geographic atrophy (GA), respectively. We measured TR volumes, RPEDC volumes, and abnormal RPEDC thickening and thinning volumes for each subject. By using different combinations of these 4 disease indicators, we designed 5 automated classifiers for the presence of AMD on the basis of the generalized linear model regression framework. We trained and evaluated the performance of these classifiers using the leave-one-out method. Main Outcome Measures The range and topographic distribution of the RPEDC and TR thicknesses in a 5-mm diameter cylinder centered at the fovea. Results The most efficient method for separating AMD and control eyes required all 4 disease indicators. The area under the curve (AUC) of the receiver operating characteristic (ROC) for this classifier was >0.99. Overall neurosensory retinal thickening in eyes with AMD versus control eyes in our study contrasts with previous smaller studies. Conclusions We identified and validated efficient biometrics to distinguish AMD from normal eyes by analyzing the topographic distribution of normal and abnormal RPEDC thicknesses across a large atlas of eyes. We created an online atlas to share the 38 400 SD-OCT images in this study, their corresponding segmentations, and quantitative measurements. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references. PMID:23993787

Farsiu, Sina; Chiu, Stephanie J.; O'Connell, Rachelle V.; Folgar, Francisco A.; Yuan, Eric; Izatt, Joseph A.; Toth, Cynthia A.

2013-01-01

382

Biomechanical properties of human thoracic spine disc segments  

PubMed Central

Background: The objective was to determine the age-dependent compressive and tensile properties of female and male thoracic spine segments using postmortem human subjects (PMHS). Materials and Methods: Forty-eight thoracic disc segments at T4-5, T6-7, T8-9, and T10-11 levels from 12 PMHS T3-T11 spinal columns were divided into groups A and B based on specimen age and loaded in compression and tension. Stiffness and elastic modulus were computed. Stiffness was defined as the slope in the linear region of the force—displacement response. Elastic modulus was defined as the slope of the stress strain curve. Analysis of Variance (ANOVA) was used to determine significant differences (P<0.05) in the disc cross-sectional area, stiffness, and elastic modulus based on gender, spinal level, and group. Results: Specimen ages in group A (28 ± 8 years) were significantly lower than in group B (70 ± 7 years). Male discs had significantly greater area (7.2 ± 2.0 sq cm) than female discs (5.9 ± 1.8 sq cm). Tensile and compressive stiffness values were significantly different between the two age groups, but not between gender and level. Specimens in group A had greater tensile (486 ± 108 N/mm) and compressive (3300 ± 642 N/mm) stiffness values compared to group B specimens (tension: 397 ± 124 N/mm, compression: 2527 ± 734 N/mm). Tensile and compressive elastic modulus values depended upon age group and gender, but not on level. Group A specimens had significantly greater tensile and compressive moduli (2.9 ± 0.8 MPa, 19.5 ± 4.1 MPa) than group B specimens (1.7 ± 0.6 MPa, 10.6 ± 3.4 MPa). Female specimens showed significantly greater tensile and compressive moduli (2.6 ± 1.0 MPa, 16.6 ± 6.4 MPa) than male specimens (2.0 ± 0.7 MPa, 13.7 ± 5.0 MPa). Discussion: Using the two groups to represent "young" and "old" specimens, this study showed that the mechanical response decreases in older specimens, and the decrease is greater in compressive than distractive properties. While the decrease is expected, the relative change between the two modes of loading has not been reported. Another conclusion from the study is that the mechanical properties depend on gender, although not as decisive due to sample size. PMID:20890410

Stemper, Brian D.; Board, Derek; Yoganandan, Narayan; Wolfla, Christopher E.

2010-01-01

383

Reversible carotid artery narrowing in morning glory disc anomaly.  

PubMed

A 14-year-old boy with morning glory disc anomaly (MGDA) and normal visual and neurologic function displayed marked carotid artery narrowing on magnetic resonance angiography (MRA). This narrowing disappeared on a follow-up MRA six months later. Optic coherence tomography and scanning laser polarimetry disclosed a normal retinal nerve fiber layer in the eye with MGDA. MGDA has been reported in association with irreversible carotid artery stenosis leading to moya moya disease. This case suggests that mild cases of MGDA may be associated with reversible carotid artery narrowing owing to vasospasm. PMID:16148627

Murphy, Marjorie A; Perlman, Elliot M; Rogg, Jeffrey M; Easton, J Donald; Easton, Donald J; Schuman, Joel S

2005-09-01

384

Environmentally benign manufacturing of compact disc stampers [Final Phase II report  

SciTech Connect

Optical data storage is currently a $10B/yr. business. With the introduction of the high capacity Digital Versatile Disc (D/D) as well as the continued growth of CD-Audio and CD-ROM worldwide sales of optical data products as a whole are growing at rate of more than 10% per year. In North America, more than 2.5 billion optical discs will be sold in 1998. By 1999, the numbers of optical discs produced for the North American market will grow to almost three billion. The optical disc manufacturing industry is dominated by Asian and European companies (e.g. Sony of Japan and Philips of Netherlands). Prism Corporation has created a process that could significantly improve US competitiveness in the business of optical disc production. The objectives of the Phase II STTR project were to build and test an ion machining system (IMS) for stamper fabrication, prove overall manufacturing system feasibility by fabrication stampers and replicas, and evaluate alternative materials and alternative process parameters to optimize the process. During tie period of the Phase II project Prism Corporation was able to meet these objectives. In the course of doing so, adjustments had been made to better the project and in turn the final product. An ion machining system was designed and built that produced stampers ready for the molding process. Also, many control steps in the manufacturing process were studied to improve the current process and make it even more compatible with the industry standards, fitting seamlessly into current manufacturing lines.

None

1999-07-08

385

Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817--330  

E-print Network

We build a simple model of the optical/UV emission from irradiation of the outer disc by the inner disc and coronal emission in black hole binaries. We apply this to the broadband Swift data from the outburst of the black hole binary XTE J1817--330 to confirm previous results that the optical/UV emission in the soft state is consistent with a reprocessing a constant fraction of the bolometric X-ray luminosity. However, this is very surprising as the disc temperature drops by more than a factor 3 in the soft state, which should produce a marked change in the reprocessing efficiency. The easiest way to match the observed constant reprocessed fraction is for the disc skin to be highly ionized (as suggested 30 years ago by van Paradijs), so that the bulk of the disc flux is reflected and only the hardest X-rays heat the disc. The constant reprocessed fraction also favours direct illumination of the disc over a scattering origin as the optical depth/solid angle of any scattering material (wind/corona) over the disc should decrease as the source luminosity declines. By contrast, the reprocessed fraction increases very significantly (by a factor ~6) as the source enters the hard state. This dramatic change is not evident from X-ray/UV flux correlations as it is masked by bandpass effects. However, it does not necessarily signal a change in emission e.g. the emergence of the jet dominating the optical/UV flux as the reflection albedo must change with the dramatic change in spectral shape.

Marek Gierlinski; Chris Done; Kim Page

2008-11-06

386

Optical Coherence Tomography in Glaucoma  

NASA Astrophysics Data System (ADS)

Retinal nerve fiber layer (RNFL) thinning and optic nerve head cupping are key diagnostic features of glaucomatous optic neuropathy. The higher resolution of the recently introduced SD-OCT offers enhanced visualization and improved segmentation of the retinal layers, providing a higher accuracy in identification of subtle changes of the optic disc and RNFL thinning associated with glaucoma.

Berisha, Fatmire; Hoffmann, Esther M.; Pfeiffer, Norbert

387

Optical coherence tomography in photodynamic therapy for subfoveal choroidal neovascularisation secondary to age related macular degeneration: a cross sectional study  

PubMed Central

Aims: To introduce new terminology and validate its reliability for the analysis of optical coherence tomography (OCT) scans, compare clinical detection of cystoid macular oedema (CMO) and subretinal fluid (SRF) with OCT findings, and to study the effect of photodynamic therapy (PDT) on the foveal morphology. Methods: Patients with subfoveal, predominantly classic choroidal neovascularisation (CNV) secondary to age related macular degeneration (AMD) undergoing PDT were evaluated with refraction protocol best corrected logMAR visual acuity (VA), slit lamp biomicroscopy, stereoscopic fluorescein angiography (FFA), and OCT. New terminologies introduced to interpret the OCT scans were: neuroretinal foveal thickness (NFT), bilaminar foveal thickness (BFT), outer high reflectivity band thickness (OHRBT), intraretinal fluid (IRF), subretinal fluid (oSRF), and vitreomacular hyaloid attachment (VMHA). Results: Fifty six eyes of 53 patients were studied. VA was better in eyes with a thinner outer high reflectivity band (OHRBT) (p?=?0.02) and BFT (p?=?0.05). BFT was less in eyes that had undergone a greater number of PDT treatments (p?=?0.04). There was poor agreement between OCT and clinical examination in the detection of CMO and subretinal fluid (??=?0.289 and ??=?0.165 respectively). To validate the interpretation and measurements on OCT, two groups of 20 scans were analysed by two independent observers. There was good agreement between the observers in the detection of IRF, oSRF, and VMHA (p<0.001). Measurements of NFT and BFT had a high reproducibility, and of OHRBT reproducibility was low. Conclusions: New terminology has been introduced and tested. OCT appears to be superior to clinical examination and FFA in the detection of CMO. In this study, better vision was associated with a thinner OHRBT and/or the absence of SRF giving insight into the biological effect of PDT. PMID:15722312

Sahni, J; Stanga, P; Wong, D; Harding, S

2005-01-01

388

Interactive Visualization of a Thin Disc around a Schwarzschild Black Hole  

ERIC Educational Resources Information Center

In a first course in general relativity, the Schwarzschild spacetime is the most discussed analytic solution to Einstein's field equations. Unfortunately, there is rarely enough time to study the optical consequences of the bending of light for some advanced examples. In this paper, we present how the visual appearance of a thin disc around a…

Muller, Thomas; Frauendiener, Jorg

2012-01-01

389

Stochastic angular momentum slews and flips and their effect on discs in galaxy formation models  

NASA Astrophysics Data System (ADS)

The angular momentum of galactic discs in semi-analytic models of galaxy formation is usually updated in time as material is accreted to the disc by adopting a constant dimensionless spin parameter and little attention is paid to the effects of accretion with misaligned angular momenta. These effects are the subject of this paper, where we adopt a Monte Carlo simulation for the changes in the direction of the angular momentum of a galaxy disc as it accretes matter based on accurate measurements from dark-matter haloes in the Millennium II simulation. In our semi-analytic model implementation, the flips seen in the dark-matter haloes are assumed to be the same for the cold baryons; however, we also assume that in the latter the flip also entails a difficulty for the disc to increase its angular momentum which causes the disc to become smaller relative to a no-flip case. This makes star formation to occur faster, especially in low-mass galaxies at all redshifts allowing galaxies to reach higher stellar masses faster. We adopt a new condition for the triggering of starbursts during mergers. As these produce the largest flips it is natural to adopt the disc instability criterion to evaluate the triggering of bursts in mergers instead of one based on mass ratios as in the original model. The new implementation reduces the average lifetimes of discs by a factor of ˜2, while still allowing old ages for the present-day discs of large spiral galaxies. It also provides a faster decline of star formation in massive galaxies and a better fit to the bright end of the luminosity function at z = 0.

Padilla, Nelson D.; Salazar-Albornoz, Salvador; Contreras, Sergio; Cora, Sofía A.; Ruiz, Andrés N.

2014-09-01

390

Effect of Mechanical Strain on Solute Diffusion in Human TMJ Discs: An Electrical Conductivity Study  

PubMed Central

This study investigated the effect of mechanical strain on solute diffusion in human TMJ discs (mean cadaver age 77.8) using the electrical conductivity method. The electrical conductivity, as well as small ion diffusivity, of male and female TMJ discs was determined under three compressive strains. In the male group, the average disc electrical conductivity (mean ± sd) at 0% strain was 5.14±0.97 mS/cm, decreased to 4.50±0.91 mS/cm (?12.3%) at 10% strain, and 3.93±0.81 mS/cm (?23.5%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.44±0.08, decreased to 0.40±0.08 (?8.9%) at 10% strain, and 0.36±0.08 (?16.7%) at 20% compressive strain. In the female group, the average disc electrical conductivity at 0% strain was 5.84±0.59 mS/cm, decreased to 5.01±0.50 mS/cm (?14.2%) at 10% strain, and 4.33±0.46 mS/cm (?25.8%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.49±0.05, decreased to 0.43±0.04 (?11.3%) at 10% strain, and 0.39±0.04 (?19.9%) at 20% compressive strain. The results indicated that mechanical strain significantly impeded solute diffusion through the disc. This mechanical strain effect was larger in the female than in the male human TMJ disc. This study may provide new insights into TMJ pathophysiology. PMID:23771300

Wright, Gregory J.; Kuo, Jonathan; Shi, Changcheng; Bacro, Thierry H.; Slate, Elizabeth H.; Yao, Hai

2013-01-01

391

The diverse formation histories of simulated disc galaxies  

NASA Astrophysics Data System (ADS)

We analyse the formation histories of 19 galaxies from cosmological smoothed particle hydrodynamics zoom-in resimulations. We construct mock three-colour images and show that the models reproduce observed trends in the evolution of galaxy colours and morphologies. However, only a small fraction of galaxies contains bars. Many galaxies go through phases of central mass growth by in situ star formation driven by gas-rich mergers or misaligned gas infall. These events lead to accretion of low angular momentum gas to the centres and leave imprints on the distributions of z = 0 stellar circularities, radii and metallicities as functions of age. Observations of the evolution of structural properties of samples of disc galaxies at z = 2.5-0.0 infer continuous mass assembly at all radii. Our simulations can only explain this if there is a significant contribution from mergers or misaligned infall, as expected in a ? cold dark matter universe. Quiescent merger histories lead to high kinematic disc fractions and inside-out growth, but show little central growth after the last `destructive' merger at z > 1.5. For sufficiently strong feedback, as assumed in our models, a moderate amount of merging does not seem to be a problem for the z = 0 disc galaxy population, but may rather be a requirement. The average profiles of simulated disc galaxies agree with observations at z ? 1.5. At z ? 1, there is too much growth in size and too little growth in central mass, possibly due to the underabundance of bars. The discrepancies may partly be caused by differences between the star formation histories of the simulations and those assumed for observations.

Aumer, Michael; White, Simon D. M.; Naab, Thorsten

2014-07-01

392

Ferromagnetic Ni(II) discs.  

PubMed

A family of planar disc-like hexa-, octa- and decametallic Ni(II) complexes exhibit dominant ferromagnetic exchange. The deca- and octametallic clusters [Ni(II) (10)(tmp)(2)(N(3))(8)(acac)(6)(MeOH)(6)] (1, H(3)tmp=1,1,1-tris(hydroxymethyl)propane; acac=acetylacetonate) and [Ni(II) (8)(thme)(2)(O(2)CPh)(4)(Cl)(6)(MeCN)(6)(H(2)O)(2)] (2, H(3)thme=1,1,1-tris(hydroxymethyl)ethane) represent rare examples of Ni(II)-based single-molecule magnets, and [Ni(II) (10)] (1) possesses the largest barrier to magnetisation reversal of any Ni(II) single-molecule magnet to date. PMID:19757431

Scott, Richard T W; Jones, Leigh F; Tidmarsh, Ian S; Breeze, Barbara; Laye, Rebecca H; Wolowska, Joanna; Stone, Daniel J; Collins, Anna; Parsons, Simon; Wernsdorfer, Wolfgang; Aromí, Guillem; McInnes, Eric J L; Brechin, Euan K

2009-11-16

393

Experimental study on the intrinsic response, optical and electrical parameters of 1.55-?m DFB BH laser diodes during aging tests  

Microsoft Academic Search

This paper reports on an investigation on the light-current, relative intensity noise, and chirp variations of life-tested InGaAsP\\/InP multiquantum-well buried heterostructure (BH) laser diodes (LDs). The devices have been stressed at highly accelerated aging conditions (I=170 mA, T=140°C for 3000 h). Typically, the operating current at constant output optical power (Iop) increases logarithmically with time in stable devices while the

Richardas Sobiestianskas; John G. Simmons; Greg Letal; Robert E. Mallard

2005-01-01

394

Towards a fully consistent Milky Way disc model - II. The local disc model and SDSS data of the NGP region  

NASA Astrophysics Data System (ADS)

We have used the self-consistent vertical disc models of the solar neighbourhood presented in Paper I, which are based on different star formation histories (SFRs) and fit the local kinematics of main-sequence stars equally well, to predict star counts towards the North Galactic Pole (NGP). We combined these four different models with the local main sequence in the filter system of the Sloan Digital Sky Survey (SDSS) and predicted the star counts in the NGP field with b > 80°. All models fit the Hess diagrams in the F-K dwarf regime better than ± 20 per cent and the star number densities in the solar neighbourhood are consistent with the observed values. The ?2 analysis shows that model A is clearly preferred with systematic deviations of a few per cent only. The SFR of model A is characterized by a maximum at an age of 10 Gyr and a decline by a factor of 4 to the present-day value of 1.4 M? pc-2 Gyr-1. The thick disc can be modelled very well by an old isothermal simple stellar population. The density profile can be approximated by a sech? function. We found a power-law index ?t= 1.16 and a scaleheight ht= 800 pc corresponding to a vertical velocity dispersion of ?t= 45.3 km s-1. About 6 per cent of the stars in the solar neighbourhood are thick-disc stars.

Just, A.; Gao, S.; Vidrih, S.

2011-03-01

395

Autologous adipose stem cells and polylactide discs in the replacement of the rabbit temporomandibular joint disc  

PubMed Central

The temporomandibular joint (TMJ) disc lacks functional replacement after discectomy. We investigated tissue-engineered bilayer polylactide (PLA) discs and autologous adipose stem cells (ASCs) as a potential replacement for the TMJ disc. These ASC discs were pre-cultured either in control or in differentiation medium, including transforming growth factor (TGF)-?1 for one week. Prior to implantation, expression of fibrocartilaginous genes was measured by qRT-PCR. The control and differentiated ASC discs were implanted, respectively, in the right and left TMJs of rabbits for six (n = 5) and 12 months (n = 5). Thereafter, the excised TMJ areas were examined with cone beam computed tomography (CBCT) and histology. No signs of infection, inflammation or foreign body reactions were detected at histology, whereas chronic arthrosis and considerable condylar hypertrophy were observed in all operated joints at CBCT. The left condyle treated with the differentiated ASC discs appeared consistently smoother and more sclerotic than the right condyle. The ASC disc replacement resulted in dislocation and morphological changes in the rabbit TMJ. The ASC discs pre-treated with TGF-?1 enhanced the condylar integrity. While adverse tissue reactions were not shown, the authors suggest that with improved attachment and design, the PLA disc and biomaterial itself would hold potential for TMJ disc replacement. PMID:23720535

Ahtiainen, Katja; Mauno, Jari; Ellä, Ville; Hagström, Jaana; Lindqvist, Christian; Miettinen, Susanna; Ylikomi, Timo; Kellomäki, Minna; Seppänen, Riitta

2013-01-01

396

The properties of discs around planets and brown dwarfs as evidence for disc fragmentation  

E-print Network

Direct imaging searches have revealed many very low-mass objects, including a small number of planetary mass objects, as wide-orbit companions to young stars. The formation mechanism of these objects remains uncertain. In this paper we present the predictions of the disc fragmentation model regarding the properties of the discs around such low-mass objects. We find that the discs around objects that have formed by fragmentation in discs hosted by Sun-like stars (referred to as 'parent' discs and 'parent' stars) are more massive than expected from the ${M}_{\\rm disc}-M_*$ relation (which is derived for stars with masses $M_*>0.2 {\\rm M}_{\\odot}$). Accordingly, the accretion rates onto these objects are also higher than expected from the $\\dot{M}_*-M_*$ relation. Moreover there is no significant correlation between the mass of the brown dwarf or planet with the mass of its disc nor with the accretion rate from the disc onto it. The discs around objects that form by disc fragmentation have larger than expected m...

Stamatellos, Dimitris

2015-01-01

397

Optics  

NSDL National Science Digital Library

This page allows users to simulate standard optic elements (lens, mirror, dielectrics, sources, apertures) and observe how light rays propagate through these elements. Element properties, such as position and focal length, can be adjusted using and a click and drag metaphor.

Wolfgang Christian

398

X-ray variability of SS 433: effects of the supercritical accretion disc  

NASA Astrophysics Data System (ADS)

We study a stochastic variability of SS 433 in the 10-4-5 × 10-2 Hz frequency range based on RXTE data, and on simultaneous observations with RXTE and optical telescopes. We find that the cross-correlation functions and power spectra depend drastically on the precession phase of the supercritical accretion disc. When the wind funnel of the disc is maximally open to the observer, a flat part emerges in the power spectrum; a break is observed at the frequency 1.7 × 10-3 Hz, with a power-law index ? ? 1.67 at higher frequencies. The soft emission forming mostly in the jets lags behind the hard and optical emission. When the observer does not see the funnel and jets (the `edge-on' disc), the power spectrum is described by a single power-law with ? ? 1.34 and no correlations between X-ray ranges are detected. We investigated two mechanisms to explain the observed variability at the open disc phase: (1) reflection of radiation at the funnel wall (X-rays and optical) and (2) the gas cooling in the jets (X-rays only). The X-ray variability is determined by the contribution of both mechanisms; however, the contribution of the jets is much higher. We found that the funnel size is (2-2.5) × 1012 cm, and the opening angle is ?f ˜ 50°. X-ray jets may consist of three fractions with different densities: 8 × 1013, 3 × 1013 and 5 × 1011 cm-3, with most of the jet's mass falling within the latter fraction. We suppose that revealed flat part in the power spectrum may be related to an abrupt change in the disc structure and viscous time-scale at the spherization radius, because the accretion disc becomes thick at this radius, h/r ˜ 1. The extent of the flat spectrum depends on the variation of viscosity at the spherization radius.

Atapin, Kirill; Fabrika, Sergei; Medvedev, Aleksei; Vinokurov, Alexander

2015-01-01

399

Conditions for the primary culture of eye imaginal discs from Drosophila melanogaster.  

PubMed

We have established a primary culture system for Drosophila eye imaginal discs. With this system, we were able to obtain neurite outgrowth from intact eye discs, eye disc fragments, and dissociated eye imaginal disc cells. Immunoreactivity to antibody 24B10 indicates that these extending neurites are photoreceptor axons. Three culture media were tested for their ability to support the survival of and neurite extension from eye disc fragments in vitro at 23 degrees C. These, with supplements, were: five parts of Schneider's Drosophila medium with four parts of basal Eagle's medium ("4 + 5"); Leibovitz's L-15 medium (L-15); and Shields and Sang's M3 modified medium (MM3). We obtained the best results with MM3 supplemented with 2% fetal bovine serum (FBS). Eye disc fragments survived in this medium for at least 20 days. Pigmentation in the nonphotoreceptor pigment cells in cultures from the prepupa required the presence of 20-hydroxyecdysone (20-HE) (1 micrograms/ml), whereas neurite outgrowth was seen in the absence of 20-HE. Donor animals had to fall within a range of ages to obtain appropriate eye disc differentiation in vitro. Eye disc from 5-h pupae (P + 5) or older commenced ommachrome synthesis in vitro in a temporal sequence close to that found in vivo, whereas the in vitro synthesis of this pigment was delayed in eye discs from younger flies. Average neurite length was not affected by age among pupae younger than P + 5; but neurite outgrowth from P + 24 was scarce, probably because by this time photoreceptor axons had already grown in vivo and were severed and unable to regenerate in vitro. Eye discs taken from third instar larvae or white prepupae continued their mitotic activity in vitro. Together with the advance of the morphogenetic furrow at the leading edge of retinal development, this observation is consistent with the evidence that pattern formation continues in vitro. Morphogenetic changes were manifested in cultures. Viability tests with calcein AM and ethidium bromide revealed few dead cells in living cultures. PMID:8568517

Li, C; Meinertzhagen, I A

1995-11-01

400

DISC1 genetics, biology and psychiatric illness  

PubMed Central

Psychiatric disorders are highly heritable, and in many individuals likely arise from the combined effects of genes and the environment. A substantial body of evidence points towards DISC1 being one of the genes that influence risk of schizophrenia, bipolar disorder and depression, and functional studies of DISC1 consequently have the potential to reveal much about the pathways that lead to major mental illness. Here, we review the evidence that DISC1 influences disease risk through effects upon multiple critical pathways in the developing and adult brain. PMID:23550053

THOMSON, Pippa A.; MALAVASI, Elise L.V.; GRÜNEWALD, Ellen; SOARES, Dinesh C.; BORKOWSKA, Malgorzata; MILLAR, J. Kirsty

2012-01-01

401

Effect of repetitive laser pulses on the electrical conductivity of intervertebral disc tissue  

SciTech Connect

The thermomechanical effect of 1.56-{mu}m fibre laser pulses on intervertebral disc cartilage has been studied using ac conductivity measurements with coaxial electrodes integrated with an optical fibre for laser radiation delivery to the tissue. The observed time dependences of tissue conductivity can be interpreted in terms of hydraulic effects and thermomechanical changes in tissue structure. The laserinduced changes in the electrical parameters of the tissue are shown to correlate with the structural changes, which were visualised using shadowgraph imaging. Local ac conductivity measurements in the bulk of tissue can be used to develop a diagnostic/monitoring system for laser regeneration of intervertebral discs. (laser biology and medicine)

Omel'chenko, A I; Sobol', E N [Institute of Laser and Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)

2009-03-31

402

Is the outcome of traditional lumbar disc surgery related to the size of the exposure?  

Microsoft Academic Search

Summary The purpose of this study was to evaluate whether wide surgical exposures result in poorer outcome of lumbar disc surgery compared to smaller traditional exposures. The aim was also to assess if a dural tear has any impact on the postoperative clinical outcome. One hundred and twenty-two patients (56 women and 66 men, mean age 40.8 years) with herniated

V. Graver; A. E. Ljunggren; B. Magnæs; M. Loeb; H. Lie

1996-01-01

403

Lithium effects on solute retrieval by excised leaf discs. [Ipomoea tricolor  

SciTech Connect

Excision of Ipomoea tricolor leaf discs results in a transient reduction in membrane transport capability which shows recovery after a 3 h aging period. After the recovery period, aged discs show both an enhanced capacity for uptake of exogenously supplied solutes: ((/sup 14/C)sucrose, (/sup 14/C)glucose, (/sup 14/C)glycine) as well as a reduced loss of photosynthetically derived /sup 14/C-assimilates, suggesting that general solute retrieval mechanisms operating in leaf tissues are initially somehow inhibited by the excision process. Inclusion of lithium (Li/sup +/), a known inhibitor of phosphatidylinositol(PI)-mediated signaling mechanisms involved in the control of cellular Ca/sup 2 +/ homeostasis, in the aging medium completely eliminates the recovery of these retrieval processes. On the other hand, treatment of Li/sup +/-treated discs with myo-inositol, which overcomes Li/sup +/-induced inhibition of the PI signalling system, results in full or nearly complete recovery of solute transport following aging. These data implicate the PI signalling system in the wounding phenomenon that results in the initial loss of solute retrieval capacity in freshly excised discs. It is possible that this control is exerted through control of H/sup +/-ATPase activity which drives transport.

Madore, M.

1987-04-01

404

Combined anterior interbody fusion and posterior pedicle screw fixation in patients with degenerative lumbar disc disease  

Microsoft Academic Search

We reviewed 47 consecutive patients with degenerative lumbar disc disease. All patients were treated by anterior interbody fusion using an autogenous iliac bone graft in combination with posterior pedicle fixation but without a posterior fusion. There were 32 men and 15 women with a mean age of 44 (range 23–56) years. One third ( n=15) of the patients had previous

M. A. El Masry; W. S. Badawy; P. Rajendran; D Chan

2004-01-01

405

Predictive Findings of Visual Outcome in Spectral Domain Optical Coherence Tomography after Ranibizumab Treatment in Age-related Macular Degeneration  

PubMed Central

Purpose To investigate which spectral domain optical coherence tomography (SD-OCT) findings predict visual outcome after anti-vascular endothelial growth factor (VEGF) treatment in neovascular age-related macular degeneration (NV-AMD). Methods We reviewed the medical records of patients with treatment-naïve NV-AMD who underwent three or more consecutive anti-VEGF injections. The patients were divided into three groups according to their changes of visual acuity (VA); improved (group I), static (group S), or worsened (group W). We assessed the incidences and values of all available SD-OCT findings of these groups, compared these findings between the three groups and compared the initial values with the post-treatment values. Results Better initial VA and longer external limiting membrane (ELM) length were associated with less change in VA after anti-VEGF treatment. The initial VA was mildly correlated with