[The 2009 performance report of the German cornea banks].

Science.gov (United States)

Schrage, N; Reinhard, T; Seitz, B; Hermel, M; Böhringer, D; Reinshagen, H

2011-03-01

In Germany, human tissue for corneal and amniotic transplantation is supplied by 27 cornea banks. The Section for Tissue Transplantation and Biotechnology of the German Ophthalmological Society records the cornea banks' activities by means of an annual questionnaire. In 2009, a total of 4,818 corneal grafts were processed by 21 responding cornea banks, and 57% were deemed suitable for transplantation. This ratio is slightly higher than the European average. In addition, German cornea banks released 1,257 amniotic grafts in 2009. German cornea banks are currently facing new regulatory issues due to updated legislation regarding tissue transplantation. Recent updates in European law have limited the cutoff time for postmortem blood sampling to 24 h, and this regulation may lead to a significant reduction in potential donors.

The healing of alkali-injured cornea is stimulated by a novel matrix regenerating agent (RGTA, CACICOL20): a biopolymer mimicking heparan sulfates reducing proteolytic, oxidative and nitrosative damage.

Science.gov (United States)

Cejkova, Jitka; Olmiere, Celine; Cejka, Cestmir; Trosan, Peter; Holan, Vladimir

2014-04-01

The efficacy of a chemically modified dextran - heparan sulfate mimicking regenerating agent (RGTA) on the healing of the rabbit cornea injured with alkali was examined. The eyes were injured with 0.15 N NaOH applied on the cornea or with 1.0 N NaOH using a 8 mm diameter filter paper disk. Then RGTA or placebo was applied on the cornea. In the last group of rabbits, corneas injured with the high alkali concentration were left without any treatment for four weeks; subsequently, the corneas were treated with RGTA or placebo. The central corneal thickness was measured using a pachymeter. The corneas were examined morphologically, immunohistochemically and for real time-PCR. Compared to control (unaffected) corneas, following the application of low alkali concentration the expression of urokinase-type plasminogen activator, metalloproteinase 9, nitric oxide synthase and xanthine oxidase was increased in the injured corneal epithelium of placebo-treated eyes, whereas the expression of antioxidant enzymes was reduced. Nitrotyrosine and malondialdehyde stainings appeared in the corneal epithelium. RGTA application suppressed the antioxidant/prooxidant imbalance and reduced the expression of the above-mentioned immunohistochemical markers. The corneal thickness increased after alkali injury, decreased during corneal healing after RGTA treatment faster than after placebo application. Following the injury with the high alkali concentration, corneal inflammation and neovascularization were highly pronounced in placebo-treated corneas, whereas in RGTA-treated corneas they were significantly supressed. When RGTA or placebo application was started later after alkali injury and corneas were ulcerated, subsequent RGTA treatment healed the majority of them. In conclusion, RGTA facilitates the healing of injured corneas via a reduction of proteolytic, oxidative and nitrosative damage.

Fibre optic spectrophotometry for the in vitro evaluation of ultraviolet radiation (UVR) spectral transmittance of rabbit corneas

International Nuclear Information System (INIS)

Walsh, J E; Fleming, D P; Bergmanson, J P G; Koehler, L V; Doughty, M J; Harmey, J H

2008-01-01

A fibre optic spectrophotometer front-end system for measuring corneas to overcome shortcomings associated with existing instruments was tested. The system allowed prompt measurement postmortem, minimizing beam pathlength to reduce the effects of scatter and unwanted refraction and eliminated optical interfaces and cuvette media. Rabbit corneas were excised immediately postmortem and placed on a detecting fibre optic coupled to an Ocean Optics spectrophotometer and illuminated by a deuterium–halogen source. The compact instrument with its small beam size allowed tissue profiling at test points across the corneal surface and efficient interchange for comparison of different tissues. This simplified system operation allowed rapid tissue altering to study induced changes on transmittance. The corneal transmittance data showed a consistent sharp cut-off at 320 nm in the ultraviolet radiation (UVR) spectrum, which decayed rapidly from postmortem swelling. Inter- and intra-corneal consistency was demonstrated by comparing data from different regions of the same cornea and those from opposite eyes. Changes to the spectra, particularly in the UVB below 300 nm, were evident when the corneal epithelium was removed, indicating that this layer is not the only corneal UVR filter. The new system reduced much of the variability associated with previous methods, as it rapidly measured corneal transmittance postmortem. Data are in broad agreement with published transmittance curves. The removal of the corneal epithelium revealed a substantial stromal contribution to the overall corneal UVR absorption, suggesting that corneas with pathologically or iatrogenically thinned stromas are less effective UVR blockers

Factors influencing the virological testing of cornea donors.

Science.gov (United States)

Röck, Tobias; Beck, Robert; Jürgens, Stefan; Bartz-Schmidt, Karl Ulrich; Bramkamp, Matthias; Thaler, Sebastian; Röck, Daniel

2017-11-01

To assess the influence of donor, environment, and logistical factors on the results of virological testing of blood samples from cornea donors.Data from 670 consecutive cornea donors were analyzed retrospectively. Logistic regression analysis was used to assess the influence of different factors on the results of virological testing of blood samples from cornea donors.The mean annual rate of donors with serology-reactive or not evaluable result was 14.8% (99 of 670) (range 11.9%-16.9%). The cause of donor death by cancer increased the risk of serology-reactive or not evaluable result (P = .0300). Prolonged time between death and post mortem blood removal was associated with a higher rate of serology-reactive or not evaluable result (P donors, sex, and donor age had no significant impact on the results of virological testing of blood samples from cornea donors.The cause of donor death by cancer and a prolonged time between death and post mortem blood removal seem to be mainly responsible for serology-reactive or not evaluable result of blood samples from cornea donors. The percentage of discarded corneas caused by serology-reactive or not evaluable result may be reduced by shortening the period of time between death and post mortem blood removal. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Pleuroscopic punch biopsy using insulated-tip diathermic knife-2 for the diagnosis of desmoplastic malignant mesothelioma.

Science.gov (United States)

Masai, Kyohei; Sasada, Shinji; Izumo, Takehiro; Taniyama, Tomoko; Nakamura, Yukiko; Chavez, Christine; Sakurai, Hiroyuki; Tsuta, Koji; Tsuchida, Takaaki

2013-10-01

Desmoplastic malignant mesothelioma (DMM) is a rare subtype of malignant pleural mesothelioma (MPM) and is often difficult to distinguish from pleural fibrosis and reactive mesothelial hyperplasia, especially if the biopsy samples are small. We performed full-thickness pleural biopsy on a lesion suspected to be DMM using an insulated-tip diathermic knife-2 (IT knife-2) during flex-rigid pleuroscopy. IT knife-2 is a novel electrosurgical device for endoscopic submucosal dissection in the early gastrointestinal cancer. It consists of a needle knife with 3 short blades at the distal end attached to an insulated ceramic tip. A 54-year-old man presenting with chest wall mass and thickened pleura, in whom a computed tomography-guided percutaneous needle aspiration had remained negative, underwent flex-rigid pleuroscopy for definitive diagnosis. While applying electric current, we used the IT knife-2 to incise the pleura in a circular shape just above the endothoracic fascia. The incised pleura was removed by forceps and examined pathologically. The microscopic examination was compatible with DMM. We discovered that pleuroscopic punch biopsy using IT knife-2 can diagnose DMM. Use of IT knife-2 during flex-rigid pleuroscopy can obtain sufficient samples from densely thickened pleura, which is difficult to diagnose with small biopsies.

Novel micelle carriers for cyclosporin A topical ocular delivery: in vivo cornea penetration, ocular distribution and efficacy studies.

Science.gov (United States)

Di Tommaso, Claudia; Bourges, Jean-Louis; Valamanesh, Fatemeh; Trubitsyn, Gregory; Torriglia, Alicia; Jeanny, Jean-Claude; Behar-Cohen, Francine; Gurny, Robert; Möller, Michael

2012-06-01

Cornea transplantation is one of the most performed graft procedures worldwide with an impressive success rate of 90%. However, for "high-risk" patients with particular ocular diseases in addition to the required surgery, the success rate is drastically reduced to 50%. In these cases, cyclosporin A (CsA) is frequently used to prevent the cornea rejection by a systemic treatment with possible systemic side effects for the patients. To overcome these problems, it is a challenge to prepare well-tolerated topical CsA formulations. Normally high amounts of oils or surfactants are needed for the solubilization of the very hydrophobic CsA. Furthermore, it is in general difficult to obtain ocular therapeutic drug levels with topical instillations due to the corneal barriers that efficiently protect the intraocular structures from foreign substances thus also from drugs. The aim of this study was to investigate in vivo the effects of a novel CsA topical aqueous formulation. This formulation was based on nanosized polymeric micelles as drug carriers. An established rat model for the prevention of cornea graft rejection after a keratoplasty procedure was used. After instillation of the novel formulation with fluorescent labeled micelles, confocal analysis of flat-mounted corneas clearly showed that the nanosized carriers were able to penetrate into all corneal layers. The efficacy of a 0.5% CsA micelle formulation was tested and compared to a physiological saline solution and to a systemic administration of CsA. In our studies, the topical CsA treatment was carried out for 14 days, and the three parameters (a) cornea transparency, (b) edema, and (c) neovascularization were evaluated by clinical observation and scoring. Compared to the control group, the treated group showed a significant higher cornea transparency and significant lower edema after 7 and 13 days of the surgery. At the end point of the study, the neovascularization was reduced by 50% in the CsA-micelle treated

GENDER AND AGE RELATED VARIATION IN CORNEA POWER

African Journals Online (AJOL)

2014-05-01

May 1, 2014 ... population and how it varies with gender and age. Design: A .... horizontal in orientation. For the purpose of .... race as cornea curvature have been noted to exhibit ... Grosevenor, T. Role of Cornea in Emmetropia and. Myopia.

ANALYSIS OF DONOR CORNEA RETRIEVAL DATA- HOSPITAL AND RESIDENCES

Directory of Open Access Journals (Sweden)

Rekha Gyanchand

2017-07-01

Full Text Available BACKGROUND The voluntary eye donation is still the most popular methods of eye donation in our country. Since last three decades, the voluntary eye donation is promoted by a number of NGOs and Government of India. The meaning of voluntary eye donation is that an individual has prior knowledge about eye donation and also has the contact number of the eye bank. When they come across any death in their community, they will contact the eye bank for eye donation. As per Eye Bank Association of India, the incidence of total blindness is 8.9 million and 1% of this is corneal blindness. Each year, 25,000 to 30,000/new corneal blind patients are added. The voluntary eye donation is not sufficient in providing transplantable corneas to the corneal blind. As our concentration is mainly on voluntary eye collections, this is one of the main reasons that we are unable reach our target of sight restoration in the management of corneal blindness. In this study, we have analysed the voluntary eye donations procured from residence and hospital. The aim of the study is to compare corneas procured by hospital eye donations and residence eye donations to look into all factors that contribute to a transplantable cornea. MATERIALS AND METHODS The donor corneas retrieved from the year 2005-2010 were analysed. The hospital eye donations and residential eye donations were divided into two study groups. The factors analysed were number of corneas collected, donor age and gender, serology test result, death to preservation time (DPT, optical grade cornea, utilisation of corneas for transplantation and role of pledging in eye donation. Study Type- Retrospective study. Study Done- At Lions International Eye Bank, Bangalore. RESULTS The total number of donor eyes collected from the year 2005-2010 were 7362 of which residence collections was 50.73% and hospital collections was 49.26%. The 5-year period between from 2005 to 2010 in spite of not conducting a Hospital Cornea

Matrix metalloproteinase expression in excimer laser wounded rabbit corneas

Science.gov (United States)

Hahn, Taewon; Chamon, Wallace; Akova, Yonja; Stark, Walter J.; Stetler-Stevenson, William G.; Azar, Dimitri T.

1994-06-01

This study was performed to obtain information about matrix metalloproteinase (MMP) expression in excimer-wounded corneas and to determine whether MMPs expression correlates with the depth of the ablation. 6-mm excimer keratectomy (60 or 180 micrometers ) was performed using the 193-mm ArF excimer laser on 12 NZW rabbits. Corneas treated with mechanical epithelial debridement and untreated corneas served as controls. Rabbits were killed at 20 and 30 hr after laser ablation. Zymography after SDS extraction was performed on regenerated central epithelium and the central stroma to determine MMPs expression. We observed enzymatic activity of a 92 KDa band in the epithelium of excimer-ablated corneas but not in that following debridement wounds and untreated controls. The expression of the 92 KDa MMP was most pronounced with the deeper excimer ablation. A 72 KDa band of enzymatic activity present in the stroma of all treated and control eyes was also seen in the epithelium of excimer-ablated corneas. These proteolytic enzymes may play an important role in wound healing and remodelling after excimer keratectomy.

File list: ALL.Oth.50.AllAg.Cornea [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available ALL.Oth.50.AllAg.Cornea mm9 All antigens Others Cornea SRX437637,SRX437636,SRX24830...2,SRX248301,SRX437638 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Oth.50.AllAg.Cornea.bed ...

File list: ALL.Oth.05.AllAg.Cornea [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available ALL.Oth.05.AllAg.Cornea mm9 All antigens Others Cornea SRX437637,SRX437636,SRX24830...2,SRX248301,SRX437638 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Oth.05.AllAg.Cornea.bed ...

File list: ALL.Oth.20.AllAg.Cornea [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available ALL.Oth.20.AllAg.Cornea mm9 All antigens Others Cornea SRX437637,SRX437636,SRX24830...2,SRX248301,SRX437638 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Oth.20.AllAg.Cornea.bed ...

File list: ALL.Oth.10.AllAg.Cornea [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available ALL.Oth.10.AllAg.Cornea mm9 All antigens Others Cornea SRX437637,SRX248302,SRX43763...6,SRX248301,SRX437638 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Oth.10.AllAg.Cornea.bed ...

Extracellular matrix alterations in human corneas with bullous keratopathy

DEFF Research Database (Denmark)

Ljubimov, A V; Burgeson, R E; Butkowski, R J

1996-01-01

PURPOSE. To uncover abnormalities of extracellular matrix (ECM) distribution in human corneas with pseudophakic and aphakic bullous keratopathy (PBK/ABK). METHODS. Indirect immunofluorescence with antibodies to 27 ECM components was used on frozen sections of 14 normal and 20 PBK/ABK corneas...... in some cases, correlated with decreased visual acuity. In normal central corneas, tenascin was never found. Other major ECM abnormalities in PBK/ABK corneas compared to normals included: discontinuous epithelial BM straining for laminin-1 (alpha 1 beta 1 gamma 1), entactin/nidogen and fibronectin......; accumulation of fibronectin and alpha 1-alpha 2 type IV collagen on the endothelial face of the Descemet's membrane; and abnormal deposition of stromal ECM (tenascin, fibronectin, decorin, types I, III, V, VI, VIII, XII, XIV collagen) and BM components (type IV, collagen, perlecan, bamacan, laminin-1, entactin...

Spontaneous regression of epithelial downgrowth from clear corneal phacoemulsification wound

Directory of Open Access Journals (Sweden)

Ryan M. Jaber

2018-06-01

Full Text Available Purpose: To report a case of spontaneous regression of optical coherence tomography (OCT and confocal microscopy-supported epithelial downgrowth associated with clear corneal phacoemulsification wound. Observations: A 66-year-old Caucasian male presented two years after phacoemulsification in the left eye with an enlarging cornea endothelial lesion in that eye. His early post-operative course had been complicated by corneal edema and iris transillumination defects. The patient presented to our clinic with a large geographic sheet of epithelial downgrowth and iris synechiae to the temporal clear corneal wound. His vision was correctable to 20/25 in his left eye. Anterior segment OCT showed a hyperreflective layer on the posterior cornea with an abrupt transition that corresponded to the clinical transition zone of the epithelial downgrowth. Confocal microscopy showed polygonal cells with hyperreflective nuclei suggestive of epithelial cells in the area of the lesion with a transition to a normal endothelial cell mosaic. Given the lack of glaucoma or inflammation and the relatively good vision, the plan was made to closely monitor for progression with the anticipation that he may require aggressive surgery. Over course of subsequent follow-up visits at three, seven and ten months; the endothelial lesion receded significantly. Confocal imaging in the area of the previously affected cornea showed essentially normal morphology with anan endothelial cell count of 1664 cells/mm2. Conclusions and importance: Epithelial downgrowth may spontaneously regress. Though the mechanism is yet understood, contact inhibition of movement may play a role. Despite this finding, epithelial downgrowth is typically a devastating process requiring aggressive treatment. Keywords: Epithelial downgrowth, Spontaneous regression, Confocal microscopy, Contact inhibition of movement

Pharmacokinetics of chlorhexidine gluconate 0.02% in the rabbit cornea.

Science.gov (United States)

Xuguang, Sun; Yanchuang, Liang; Feng, Zhang; Shiyun, Luo; Xiaotang, Yin

2006-08-01

The aim of this study was to determine the pharmacokinetic parameters of chlorhexidine gluconate (CHG) in the rabbit cornea. Each eye of 16 New Zealand white rabbits were topically instilled with 50 microL of CHG 0.02% eye drops twice with a 5-min interval. Four (4) corneas of 2 rabbits were harvested at each time point. The concentration of CHG in the cornea was determined with high-performance liquid chromatography (HPLC) and 387 software to simulate the pharmacokinetic parameters. The concentration of CHG in the cornea displayed an open two-compartment model. Tmax was 13.75 min, Cmax 0.713 microg.g1, clearance rate 1.64 microg.g-1.min-1, and t1/2alpha, t1/2beta, and t1/2ka was 2.65, 48.72, and 2.67 min, respectively. The concentration of CHG in the rabbit cornea could be determined by means of HPLC. The maximum concentration of CHG in the corneal tissue was much higher than the trophozoite minimum amoebicidal concentration (TMAC) in vitro.

CORNEA AND ANTERIOR SEGMENT

African Journals Online (AJOL)

Yet, fewer than 150,000 corneal transplant surgeries are performed annually worldwide. Corneal blindness arises from a wide variety of causes, from mechanical, chemical, and radiation injury to microbial infections and corneal degenerative diseases. The use of human cadaver donor corneas has been limited by its often.

Melatonin Entrains PER2::LUC Bioluminescence Circadian Rhythm in the Mouse Cornea

Science.gov (United States)

Baba, Kenkichi; Davidson, Alec J.; Tosini, Gianluca

2015-01-01

Purpose Previous studies have reported the presence of a circadian rhythm in PERIOD2::LUCIFERASE (PER2::LUC) bioluminescence in mouse photoreceptors, retina, RPE, and cornea. Melatonin (MLT) modulates many physiological functions in the eye and it is believed to be one of the key circadian signals within the eye. The aim of the present study was to investigate the regulation of the PER2::LUC circadian rhythm in mouse cornea and to determine the role played by MLT. Methods Corneas were obtained from PER2::LUC mice and cultured to measure bioluminescence rhythmicity in isolated tissue using a Lumicycle or CCD camera. To determine the time-dependent resetting of the corneal circadian clocks in response to MLT or IIK7 (a melatonin type 2 receptor, MT2, agonist) was added to the cultured corneas at different times of the day. We also defined the location of the MT2 receptor within different corneal layers using immunohistochemistry. Results A long-lasting bioluminescence rhythm was recorded from cultured PER2::LUC cornea and PER2::LUC signal was localized to the corneal epithelium and endothelium. MLT administration in the early night delayed the cornea rhythm, whereas administration of MLT at late night to early morning advanced the cornea rhythm. Treatment with IIK7 mimicked the MLT phase-shifting effect. Consistent with these results, MT2 immunoreactivity was localized to the corneal epithelium and endothelium. Conclusions Our work demonstrates that MLT entrains the PER2::LUC bioluminescence rhythm in the cornea. Our data indicate that the cornea may represent a model to study the molecular mechanisms by which MLT affects the circadian clock. PMID:26207312

The structural response of the cornea to changes in stromal hydration.

Science.gov (United States)

Hayes, Sally; White, Tomas; Boote, Craig; Kamma-Lorger, Christina S; Bell, James; Sorenson, Thomas; Terrill, Nick; Shebanova, Olga; Meek, Keith M

2017-06-01

The primary aim of this study was to quantify the relationship between corneal structure and hydration in humans and pigs. X-ray scattering data were collected from human and porcine corneas equilibrated with polyethylene glycol (PEG) to varying levels of hydration, to obtain measurements of collagen fibril diameter, interfibrillar spacing (IFS) and intermolecular spacing. Both species showed a strong positive linear correlation between hydration and IFS 2 and a nonlinear, bi-phasic relationship between hydration and fibril diameter, whereby fibril diameter increased up to approximately physiological hydration, H = 3.0, with little change thereafter. Above H = 3.0, porcine corneas exhibited a larger fibril diameter than human corneas ( p < 0.001). Intermolecular spacing also varied with hydration in a bi-phasic manner but reached a maximum value at a lower hydration ( H = 1.5) than fibril diameter. Human corneas displayed a higher intermolecular spacing than porcine corneas at all hydrations ( p < 0.0001). Human and porcine corneas required a similar PEG concentration to reach physiological hydration, suggesting that the total fixed charge that gives rise to the swelling pressure is the same. The difference in their structural responses to hydration can be explained by variations in molecular cross-linking and intra/interfibrillar water partitioning. © 2017 The Authors.

Advanced Squamous Cell Carcinoma of Cornea in a Child with ...

African Journals Online (AJOL)

lids, conjunctiva, and cornea are affected by the disease process.[3] A case of XP ... In the left eye, almost the entire cornea was involved with a grayish-white, irregular, and ... referring to its characteristic dry pigmented skin. It was also named ...

Correlation between epithelial thickness in normal corneas, untreated ectatic corneas, and ectatic corneas previously treated with CXL; is overall epithelial thickness a very early ectasia prognostic factor?

Directory of Open Access Journals (Sweden)

Kanellopoulos AJ

2012-05-01

Full Text Available Anastasios John Kanellopoulos,1,2 Ioannis M Aslanides,3 George Asimellis11Laservision Eye Institute, Athens, 2Emmetropia Mediterranean Eye Clinic, Crete, Greece, 3New York University School of Medicine, NY, USAPurpose: To determine and correlate epithelial corneal thickness (pachymetric measurements taken with a digital arc scanning very high frequency ultrasound biomicroscopy (HF UBM imaging system (Artemis-II, and compare mean and central epithelial thickness among normal eyes, untreated keratoconic eyes, and keratoconic eyes previously treated with collagen crosslinking (CXL.Methods: Epithelial pachymetry measurements (topographic mapping were conducted on 100 subjects via HF UBM. Three groups of patients were included: patients with normal eyes (controls, patients with untreated keratoconic eyes, and patients with keratoconic eyes treated with CXL. Central, mean, and peripheral corneal epithelial thickness was examined for each group, and a statistical study was conducted.Results: Mean, central, and peripheral corneal epithelial thickness was compared between the three groups of patients. Epithelium thickness varied substantially in the keratoconic group, and in some cases there was a difference of up to 20 µm between various points of the same eye, and often a thinner epithelium coincided with a thinner cornea. However, on average, data from the keratoconic group suggested an overall thickening of the epithelium, particularly over the pupil center of the order of +3 µm, while the mean epithelium thickness was on average +1.1 µm, compared to the control population (P = 0.005. This overall thickening was more pronounced in younger patients in the keratoconic group. Keratoconic eyes previously treated with CXL showed, on average, virtually the same average epithelium thickness (mean –0.7 µm, –0.2 µm over the pupil center, –0.9 µm over the peripheral zone as the control group. This finding further reinforces our novel theory of the

Analysis of Riboflavin Compounds in the Rabbit Cornea In Vivo.

Science.gov (United States)

Hammer, Arthur; Rudaz, Serge; Guinchard, Sylvie; Kling, Sabine; Richoz, Olivier; Hafezi, Farhad

2016-09-01

To investigate the composition and concentration of individual riboflavin compounds in the corneal stroma in vivo after soaking with various commercially available riboflavin formulations. Experiments were performed in 26 rabbit corneas in vivo: 24 corneas were soaked with riboflavin formulations for 30 minutes or with 0.9% NaCl for control (n = 2). After treatment, corneas were excised and prepared for ultra-high-pressure liquid chromatography (UHPLC) analysis. Additionally, computational chemical analysis of riboflavin compounds and keratan sulfate were performed. The amount of riboflavin and riboflavin phosphate isomers in cornea decreased by a factor of 10 to 100, when compared to the amount in riboflavin formulations. In particular, we found an inverse relationship in the ratio of riboflavin to riboflavin phosphate isomer concentration between formulations and cornea. The electronegativity and ionization potential of riboflavin and phosphate isomers are different. The inverse relationship observed might be explained by a stronger electronegativity of the phosphate isomers, leading to a stronger repulsion by corneal proteoglycans. Indicating the individual concentration of riboflavin compounds in formulations is more representative than the total riboflavin concentration. Riboflavin formulations and CXL protocols might be improved considering the differences in diffusion and ionization potentials of the different riboflavin compounds.

Clinical and epidemiological aspects of cornea transplant patients of a reference hospital 1

Science.gov (United States)

Cruz, Giovanna Karinny Pereira; de Azevedo, Isabelle Campos; Carvalho, Diana Paula de Souza Rego Pinto; Vitor, Allyne Fortes; Santos, Viviane Euzébia Pereira; Ferreira, Marcos Antonio

2017-01-01

ABSTRACT Objective: clinically characterizing cornea transplant patients and their distribution according to indicated and post-operative conditions of cornea transplantation, as well as estimating the average waiting time. Method: a cross-sectional, descriptive and analytical study performed for all cornea transplants performed at a reference service (n=258). Data were analyzed using Statistical Package for the Social Sciences, version 20.0. Results: the main indicator for cornea transplant was keratoconus. The mean waiting time for the transplant was approximately 5 months and 3 weeks for elective transplants and 9 days for urgent cases. An association between the type of corneal disorder with gender, age, previous surgery, eye classification, glaucoma and anterior graft failure were found. Conclusion: keratoconus was the main indicator for cornea transplant. Factors such as age, previous corneal graft failure (retransplantation), glaucoma, cases of surgeries prior to cornea transplant (especially cataract surgery) may be related to the onset corneal endothelium disorders. PMID:28614429

Wound-Healing Studies in Cornea and Skin: Parallels, Differences and Opportunities.

Science.gov (United States)

Bukowiecki, Anne; Hos, Deniz; Cursiefen, Claus; Eming, Sabine A

2017-06-12

The cornea and the skin are both organs that provide the outer barrier of the body. Both tissues have developed intrinsic mechanisms that protect the organism from a wide range of external threats, but at the same time also enable rapid restoration of tissue integrity and organ-specific function. The easy accessibility makes the skin an attractive model system to study tissue damage and repair. Findings from skin research have contributed to unravelling novel fundamental principles in regenerative biology and the repair of other epithelial-mesenchymal tissues, such as the cornea. Following barrier disruption, the influx of inflammatory cells, myofibroblast differentiation, extracellular matrix synthesis and scar formation present parallel repair mechanisms in cornea and skin wound healing. Yet, capillary sprouting, while pivotal in proper skin wound healing, is a process that is rather associated with pathological repair of the cornea. Understanding the parallels and differences of the cellular and molecular networks that coordinate the wound healing response in skin and cornea are likely of mutual importance for both organs with regard to the development of regenerative therapies and understanding of the disease pathologies that affect epithelial-mesenchymal interactions. Here, we review the principal events in corneal wound healing and the mechanisms to restore corneal transparency and barrier function. We also refer to skin repair mechanisms and their potential implications for regenerative processes in the cornea.

Diffusion of protein through the human cornea.

Science.gov (United States)

Charalel, Resmi A; Engberg, Kristin; Noolandi, Jaan; Cochran, Jennifer R; Frank, Curtis; Ta, Christopher N

2012-01-01

To determine the rate of diffusion of myoglobin and bovine serum albumin (BSA) through the human cornea. These small proteins have hydrodynamic diameters of approximately 4.4 and 7.2 nm, and molecular weights of 16.7 and 66 kDa, for myoglobin and BSA, respectively. Diffusion coefficients were measured using a diffusion chamber where the protein of interest and balanced salt solution were in different chambers separated by an ex vivo human cornea. Protein concentrations in the balanced salt solution chamber were measured over time. Diffusion coefficients were calculated using equations derived from Fick's law and conservation of mass in a closed system. Our experiments demonstrate that the diffusion coefficient of myoglobin is 5.5 ± 0.9 × 10(-8) cm(2)/s (n = 8; SD = 1.3 × 10(-8) cm(2)/s; 95% CI: 4.6 × 10(-8) to 6.4 × 10(-8) cm(2)/s) and the diffusion coefficient of BSA is 3.1 ± 1.0 × 10(-8) cm(2)/s (n = 8; SD = 1.4 × 10(-8) cm(2)/s; 95% CI: 2.1 × 10(-8) to 4.1 × 10(-8) cm(2)/s). Our study suggests that molecules as large as 7.2 nm may be able to passively diffuse through the human cornea. With applications in pharmacotherapy and the development of an artificial cornea, further experiments are warranted to fully understand the limits of human corneal diffusion and its clinical relevance. Copyright © 2012 S. Karger AG, Basel.

MODIS Collection 6 Clear Sky Restoral (CSR): Filtering Cloud Mast 'Not Clear' Pixels

Science.gov (United States)

Meyer, Kerry G.; Platnick, Steven Edward; Wind, Galina; Riedi, Jerome

2014-01-01

Correctly identifying cloudy pixels appropriate for the MOD06 cloud optical and microphysical property retrievals is accomplished in large part using results from the MOD35 1km cloud mask tests (note there are also two 250m subpixel cloud mask tests that can convert the 1km cloudy designations to clear sky). However, because MOD35 is by design clear sky conservative (i.e., it identifies "not clear" pixels), certain situations exist in which pixels identified by MOD35 as "cloudy" are nevertheless likely to be poor retrieval candidates. For instance, near the edge of clouds or within broken cloud fields, a given 1km MODIS field of view (FOV) may in fact only be partially cloudy. This can be problematic for the MOD06 retrievals because in these cases the assumptions of a completely overcast homogenous cloudy FOV and 1-dimensional plane-parallel radiative transfer no longer hold, and subsequent retrievals will be of low confidence. Furthermore, some pixels may be identified by MOD35 as "cloudy" for reasons other than the presence of clouds, such as scenes with thick smoke or lofted dust, and should therefore not be retrieved as clouds. With such situations in mind, a Clear Sky Restoral (CSR) algorithm was introduced in C5 that attempts to identify pixels expected to be poor retrieval candidates. Table 1 provides SDS locations for CSR and partly cloudy (PCL) pixels.

Accelerating repaired basement membrane after bevacizumab treatment on alkali-burned mouse cornea

Science.gov (United States)

Lee, Koon-Ja; Lee, Ji-Young; Lee, Sung Ho; Choi, Tae Hoon

2013-01-01

To understand the corneal regeneration induced by bevacizumab, we investigated the structure changes of stroma and basement membrane regeneration. A Stick soaked in 0.5 N NaOH onto the mouse cornea and 2.5 mg/ml of bevacizumab was delivered into an alkali-burned cornea (2 μl) by subconjunctival injections at 1 hour and 4 days after injury. At 7 days after injury, basement membrane regeneration was observed by transmission electron microscope. Uneven and thin epithelial basement membrane, light density of hemidesmosomes, and edematous collagen fibril bundles are shown in the alkali-burned cornea. Injured epithelial basement membrane and hemidesmosomes and edematous collagen fibril bundles resulting from alkali-burned mouse cornea was repaired by bevacizumab treatment. This study demonstrates that bevacizumab can play an important role in wound healing in the cornea by accelerating the reestablishment of basement membrane integrity that leads to barriers for scar formation. [BMB Reports 2013; 46(4): 195-200] PMID:23615260

Dendritic cells in the cornea during Herpes simplex viral infection and inflammation.

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Kwon, Min S; Carnt, Nicole A; Truong, Naomi R; Pattamatta, Ushasree; White, Andrew J; Samarawickrama, Chameen; Cunningham, Anthony L

2017-11-10

Herpes simplex keratitis is commonly caused by Herpes simplex virus type 1, which primarily infects eyelids, corneas, or conjunctiva. Herpes simplex virus type 1-through sophisticated interactions with dendritic cells (DCs), a type of antigen-presenting cell)-initiates proinflammatory responses in the cornea. Corneas were once thought to be an immune-privileged region; however, with the recent discovery of DCs that reside in the cornea, this long-held conjecture has been overturned. Therefore, evaluating the clinical, preclinical, and cell-based studies that investigate the roles of DCs in corneas infected with Herpes simplex virus is critical. With in vivo confocal microscopy, animal models, and cell culture experiments, we may further the understanding of the sophisticated interactions of Herpes simplex virus with DCs in the cornea and the molecular mechanism associated with it. It has been shown that specific differentiation of DCs using immunohistochemistry, flow cytometry, and polymerase chain reaction analysis in both human and mice tissues and viral tissue infections are integral to increasing understanding. As for in vivo confocal microscopy, it holds promise as it is the least invasive and a real-time investigation. These tools will facilitate the discovery of various targets to develop new treatments. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparison of the Keratometric Corneal Astigmatic Power after Phacoemulsification: Clear Temporal Corneal Incision versus Superior Scleral Tunnel Incision

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Yongqi He

2009-01-01

Full Text Available Objective. This is prospective randomized control trial to compare the mean keratometric corneal astigmatism diopter power (not surgical induced astigmatism among preop and one-month and three-month postop phacoemulcification of either a clear temporal corneal incision or a superior scleral tunnel Incision, using only keratometric astigmatic power reading to evaluate the difference between the two cataract surgery incisions. Methods. 120 patients (134 eyes underwent phacoemulcification were randomly assigned to two groups: Group A, the clear temporal corneal incision group, and Group B, the superior scleral tunnel incision group. SPSS11.5 Software was used for statistical analysis to compare the postsurgical changes of cornea astigmatism on keratometry. Results. The changes of corneal astigmatic diopter in Groups A and B after 3 month postop from keratometric reading were 1.04 + 0.76 and 0.94 + 0.27, respectively (=.84>.05, which showed no statistic significance difference. Conclusion. The incision through either temporal clear cornea or superior scleral tunnel in phacoemulcification shows no statistic difference in astigmatism change on keratometry 3-month postop.

Use of Fourier-Domain Optical Coherence Tomography to Evaluate Anterior Stromal Opacities in Donor Corneas

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Matthew R. Bald

2013-01-01

Full Text Available Purpose. To evaluate Fourier-domain optical coherence tomography (FD-OCT as an adjunct to traditional slit lamp examination of donor corneas with suspected Anterior Stromal Opacities. Methods. Seven corneas suspected of having anterior stromal opacities by slit lamp examination were evaluated with FD-OCT. Each cornea was evaluated to confirm the presence of opacity and, if present, the depth of opacity was measured. Results. The opacity depth ranged from 82 μm to 624 μm. The initial slit lamp impressions of five of the seven corneas were confirmed by OCT. In two corneas, the OCT findings were different from the initial slit lamp impressions. Slit lamp examination of the first cornea gave the impression of anterior stromal scarring, but OCT showed that the opacity was limited to the epithelium. Slit lamp examination of the second cornea suggested opacity limited to the epithelium, but OCT identified significant sub-Bowman's scarring. In all cases, the Eye Bank Technicians reported that the location and depth of corneal opacity were more sharply defined by OCT than by slit lamp. Conclusion. The high resolution of OCT makes it easier to determine the location of corneal opacities compared to slit lamp examinations. This enhanced visualization can improve decisions regarding transplant suitability of donor corneas.

Thick keratoconic cornea associated with posterior polymorphous corneal dystrophy.

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Zaarour, K; Slim, E; Antoun, J; Waked, N

2017-03-01

We herein report a case of bilateral unusually thick non-edematous keratoconic corneas with associated endothelial features of posterior polymorphous corneal dystrophy (PPCD). We report the case of a 27-year-old myopic woman who presented for refractive surgery. Slit lamp exam showed bilateral corneal protrusion with diffuse deep stromal and endothelial vesicular opacities and small paracentral bands. Topography showed generalized advanced corneal steepening in both eyes with increased anterior and posterior central corneal elevations in comparison to the best fit sphere. Ultrasound pachymetry showed central corneal thickness of 605μm (RE) and 612μm (LE). On specular biomicroscopy, cell density of 2503 cells/mm 2 RE and 1526 cells/mm 2 LE with significant cellular pleomorphism and polymegathism were noted. Clinical and paraclinical findings together suggest the presence of simultaneous keratoconus and PPCD. The literature has suggested an association between PPCD and steep cornea. Moreover, many reports have also described cases of associated PPCD and keratoconus with characteristic thinning and ectasia, in comparison to the unusual thick corneas noted in our patient, despite the absence of edema. Identification of genetics factors is further needed to clarify this association. This case describes a patient whose corneas present features of both keratoconus and PPCD and is unique due to the presence of increased corneal thickness despite the absence of edema. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Correlation between epithelial thickness in normal corneas, untreated ectatic corneas, and ectatic corneas previously treated with CXL; is overall epithelial thickness a very early ectasia prognostic factor?

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Kanellopoulos, Anastasios John; Aslanides, Ioannis M; Asimellis, George

2012-01-01

To determine and correlate epithelial corneal thickness (pachymetric) measurements taken with a digital arc scanning very high frequency ultrasound biomicroscopy (HF UBM) imaging system (Artemis-II), and compare mean and central epithelial thickness among normal eyes, untreated keratoconic eyes, and keratoconic eyes previously treated with collagen crosslinking (CXL). Epithelial pachymetry measurements (topographic mapping) were conducted on 100 subjects via HF UBM. Three groups of patients were included: patients with normal eyes (controls), patients with untreated keratoconic eyes, and patients with keratoconic eyes treated with CXL. Central, mean, and peripheral corneal epithelial thickness was examined for each group, and a statistical study was conducted. Mean, central, and peripheral corneal epithelial thickness was compared between the three groups of patients. Epithelium thickness varied substantially in the keratoconic group, and in some cases there was a difference of up to 20 μm between various points of the same eye, and often a thinner epithelium coincided with a thinner cornea. However, on average, data from the keratoconic group suggested an overall thickening of the epithelium, particularly over the pupil center of the order of +3 μm, while the mean epithelium thickness was on average +1.1 μm, compared to the control population (P = 0.005). This overall thickening was more pronounced in younger patients in the keratoconic group. Keratoconic eyes previously treated with CXL showed, on average, virtually the same average epithelium thickness (mean -0.7 μm, -0.2 μm over the pupil center, -0.9 μm over the peripheral zone) as the control group. This finding further reinforces our novel theory of the "reactive" component of epithelial thickening in corneas that are biomechanically unstable, becoming stable when biomechanical rigidity is accomplished despite persistence of cornea topographic irregularity. A highly irregular epithelium may be

Comparison of the characteristics in hen and quail corneas as experimental models of refractive surgery.

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Gonçalves, G C; Pérez-Merino, P; Martínez-García, M C; Barcía, A; Merayo-Loves, J

2016-07-01

To compare the histological, morphological and the biophysical measurements between hen and quail corneas, in order to determine which of them were better suited for use as an animal model for research into corneal refractive surgery. A study was performed using the biophysical measurements of the cornea (curvature, thickness, refraction, and axial length) of 20 animals (10 hens and 10 quails). The corneas were then prepared for histological analysis under microscopy light. The analysis showed that both groups have the same number of corneal layers as the human cornea and with an evident Bowman's layer. The thickness of the hen cornea and axial length of the eye, 225.3±18.4μm and 12.8±0.25mm, respectively, were larger than that of the quail (Phen central cornea, 3.65±0.08mm, was greater than that for the quail (Ppower of each cornea was similar. The proportion of total corneal thickness of the hen stroma, 82.6%, was more similar to that of the human than was the quail stroma, 72.5%. Within the hen stroma, the density of keratocytes, 8.57±1.49 per 5,000μm(2), was about half that in the quail stroma (Phen cornea, the stromal thickness and proportional similarity of the corneal layers with human cornea, the hen maybe better than the quail as an alternative species suitable for use in studies of corneal refractive surgery. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Factors influencing the contamination rate of human organ-cultured corneas.

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Röck, Daniel; Wude, Johanna; Bartz-Schmidt, Karl U; Yoeruek, Efdal; Thaler, Sebastian; Röck, Tobias

2017-12-01

To assess the influence of donor, environment and storage factors on the contamination rate of organ-cultured corneas, to consider the microbiological species causing corneal contamination and to investigate the corresponding sensitivities. Data from 1340 consecutive donor corneas were analysed retrospectively. Logistic regression analysis was used to assess the influence of different factors on the contamination rate of organ-cultured corneas for transplantation. The mean annual contamination rate was 1.8 ± 0.4% (range: 1.3-2.1%); 50% contaminations were of fungal origin with exclusively Candida species, and 50% contaminations were of bacterial origin with Staphylococcus species being predominant. The cause of donor death including infection and multiple organ dysfunction syndrome increased the risk of bacterial or fungal contamination during organ culture (p = 0.007 and p = 0.014, respectively). Differentiating between septic and aseptic donors showed an increased risk of contamination for septic donors (p = 0.0020). Mean monthly temperature including warmer months increased the risk of contamination significantly (p = 0.0031). Sex, donor age, death to enucleation, death to corneoscleral disc excision and storage time did not increase the risk of contamination significantly. The genesis of microbial contamination in organ-cultured donor corneas seems to be multifactorial. The main source of fungal or bacterial contamination could be resident species from the skin flora. The rate of microbial contamination in organ-cultured donor corneas seems to be dependent on the cause of donor death and mean monthly temperature. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

In vitro confocal imaging of the rabbit cornea.

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Masters, B R; Paddock, S

1990-05-01

We were able to observe in vitro the fine structure of the rabbit cornea using a laser scanning confocal microscope, especially in the regions between Descemet's membrane and the epithelial basal lamina. We observed submicrometre filaments throughout the stroma with high concentrations adjacent to Descemet's membrane, and found extensive interconnecting processes between stromal keratocytes. There are numerous regions containing nerve plexuses in the stroma. We found a deeply convoluted basal lamina adjacent to the epithelium, and observed regions containing junctions between endothelial cells in fluorescent images of rabbit corneas stained with the actin-specific compound fluorescein phalloidin.

Lens regeneration from the cornea requires suppression of Wnt/β-catenin signaling.

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Hamilton, Paul W; Sun, Yu; Henry, Jonathan J

2016-04-01

The frog, Xenopus laevis, possesses a high capacity to regenerate various larval tissues, including the lens, which is capable of complete regeneration from the cornea epithelium. However, the molecular signaling mechanisms of cornea-lens regeneration are not fully understood. Previous work has implicated the involvement of the Wnt signaling pathway, but molecular studies have been very limited. Iris-derived lens regeneration in the newt (Wolffian lens regeneration) has shown a necessity for active Wnt signaling in order to regenerate a new lens. Here we provide evidence that the Wnt signaling pathway plays a different role in the context of cornea-lens regeneration in Xenopus. We examined the expression of frizzled receptors and wnt ligands in the frog cornea epithelium. Numerous frizzled receptors (fzd1, fzd2, fzd3, fzd4, fzd6, fzd7, fzd8, and fzd10) and wnt ligands (wnt2b.a, wnt3a, wnt4, wnt5a, wnt5b, wnt6, wnt7b, wnt10a, wnt11, and wnt11b) are expressed in the cornea epithelium, demonstrating that this tissue is transcribing many of the ligands and receptors of the Wnt signaling pathway. When compared to flank epithelium, which is lens regeneration incompetent, only wnt11 and wnt11b are different (present only in the cornea epithelium), identifying them as potential regulators of cornea-lens regeneration. To detect changes in canonical Wnt/β-catenin signaling occurring within the cornea epithelium, axin2 expression was measured over the course of regeneration. axin2 is a well-established reporter of active Wnt/β-catenin signaling, and its expression shows a significant decrease at 24 h post-lentectomy. This decrease recovers to normal endogenous levels by 48 h. To test whether this signaling decrease was necessary for lens regeneration to occur, regenerating eyes were treated with either 6-bromoindirubin-3'-oxime (BIO) or 1-azakenpaullone - both activators of Wnt signaling - resulting in a significant reduction in the percentage of cases with successful

[Cornea bank of Lyon: from quality diagnosis to ISO 9001 certification].

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Pascal, P; Chalochet, A; Damour, O

2001-12-01

The tissue and cell bank of the HCL (Hospices Civils de Lyon) has, since 10 June 1999, consisted of two sections with related activities: cell culture for the Skin Substitutes Laboratory (Laboratoire des Substituts Cutanés, LSC) and preservation of corneas at 31 degrees C for the Cornea Bank. As the LSC had been ISO 9001 certified since March 1997 our aim, since merger, was to raise the Cornea Bank to the same level of quality as the LSC, so as to coincide with the renewal of the LSC certificate in February 2000. The methods we used (project, quality control, analysis and process optimization) led us to receive official certification only nine months after the merger. The procedure started with a program of quality control at the Cornea Bank from February 1999 onwards, in order to list the work and equipment required, evaluate its documentation system and what was needed to incorporate this new activity into the existing system of quality assurance at the LSC. On the 7th March 2000, the Tissue and Cell Bank of the HCL obtained an ISO 9001 certificate for its combined functions. As well as achieving our objectives and the strong points highlighted by the auditor during the renewal process, this quality assessment revealed many advantages: improvements in the conservation of corneas, economies in staff replacement and reductions in both the cost of maintaining quality, the cost of the corneas themselves, etc. The decree 'Banque' no. 99-741 of 30th August 1999, which put in place the system of authorization of tissue banks in France, demands quality control. Our application for certification which started in early 1999 had anticipated this regulation. This helped us enormously when compiling the dossier accompanying the official request and was an essential element in obtaining the favourable response of the ASSAPS on 21 June 2000.

Accelerating repaired basement membrane after bevacizumab treatment on alkali-burned mouse cornea

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Koon-Ja Lee

2013-04-01

Full Text Available To understand the corneal regeneration induced by bevacizumab,we investigated the structure changes of stroma andbasement membrane regeneration. A Stick soaked in 0.5 NNaOH onto the mouse cornea and 2.5 mg/ml of bevacizumabwas delivered into an alkali-burned cornea (2 μl by subconjunctivalinjections at 1 hour and 4 days after injury. At 7 daysafter injury, basement membrane regeneration was observedby transmission electron microscope. Uneven and thin epithelialbasement membrane, light density of hemidesmosomes,and edematous collagen fibril bundles are shown in thealkali-burned cornea. Injured epithelial basement membraneand hemidesmosomes and edematous collagen fibril bundlesresulting from alkali-burned mouse cornea was repaired bybevacizumab treatment. This study demonstrates that bevacizumabcan play an important role in wound healing in thecornea by accelerating the reestablishment of basementmembrane integrity that leads to barriers for scar formation.[BMB Reports 2013; 46(4: 195-200

Facoemulsificação por córnea clara no meridiano mais curvo Phacoemulsification using clear cornea incision in steepest meridian

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Fernando Pistarini Gonçalves

2007-03-01

Full Text Available OBJETIVOS: Avaliar o efeito da facoemulsificação com incisão em córnea clara no meridiano mais curvo sobre a magnitude do astigmatismo ceratométrico pré-operatório. Mapear a magnitude do astigmatismo cirurgicamente induzido por incisões nas posições nasal (N, temporal (T, temporal superior (TS e temporal inferior (TI. MÉTODOS: Foi realizado estudo ceratométrico prospectivo em 48 olhos de 48 pacientes, submetidos a facoemulsificação com incisão do meridiano mais curvo. As medidas ceratométricas foram realizadas no pré-operatório e um mês após a realização da cirurgia. O astigmatismo cirurgicamente induzido foi determinado pelo método das coordenadas retangulares em 10 passos, modificado. RESULTADOS: Foram operados 21 olhos direitos e 27 olhos esquerdos e, de acordo com a posição das incisões em córnea clara, foram divididos em: 16 olhos N, 4 olhos T, 22 olhos TS, 6 olhos TI. A média da ametropia cilíndrica pré-operatória foi de 1,06D ± 0,65 e a pós-operatória de 0,89D ± 0,80. Houve diminuição estatisticamente significativa no astigmatismo corneal preexistente (p=0,016. A média total de astigmatismo cirurgicamente induzido foi de 0,94D ± 0,56. Em relação aos grupos o astigmatismo cirurgicamente induzido foi de 1,06D ± 0,66 em N, 0,87D ± 0,20 em T, 0,95D ± 0,55 em TS e 0,61D ± 0,25 em TI. Não houve diferença estatística com relação ao astigmatismo cirurgicamente induzido nos grupos N, T, TS e TI (p=0,426. CONCLUSÃO: A técnica se mostrou efetiva na redução do astigmatismo ceratométrico pré-operatório. A média do astigmatismo cirurgicamente induzido foi de 1,06D ± 0,66 em N, 0,95D ± 0,55 em TS, 0,61D ± 0,25 em T e 0,87D ± 0,20 em TI.PURPOSE: To evaluate the effect of phacoemulsification through clear cornea incision in the steepest meridian (ISM, on the magnitude of preoperative keratometric astigmatism. To map the magnitude of surgically induced astigmatism (SIA by clear cornea incision

Cornea nerve fiber quantification and construction of phenotypes in patients with fibromyalgia.

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Oudejans, Linda; He, Xuan; Niesters, Marieke; Dahan, Albert; Brines, Michael; van Velzen, Monique

2016-03-23

Cornea confocal microscopy (CCM) is a novel non-invasive method to detect small nerve fiber pathology. CCM generally correlates with outcomes of skin biopsies in patients with small fiber pathology. The aim of this study was to quantify the morphology of small nerve fibers of the cornea of patients with fibromyalgia in terms of density, length and branching and further phenotype these patients using standardized quantitative sensory testing (QST). Small fiber pathology was detected in the cornea of 51% of patients: nerve fiber length was significantly decreased in 44% of patients compared to age- and sex-matched reference values; nerve fiber density and branching were significantly decreased in 10% and 28% of patients. The combination of the CCM parameters and sensory tests for central sensitization, (cold pain threshold, mechanical pain threshold, mechanical pain sensitivity, allodynia and/or windup), yielded four phenotypes of fibromyalgia patients in a subgroup analysis: one group with normal cornea morphology without and with signs of central sensitization, and a group with abnormal cornea morphology parameters without and with signs of central sensitization. In conclusion, half of the tested fibromyalgia population demonstrates signs of small fiber pathology as measured by CCM. The four distinct phenotypes suggest possible differences in disease mechanisms and may require different treatment approaches.

Sorption of sodium hydroxide by type I collagen and bovine corneas.

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Whikehart, D R; Edwards, W C; Pfister, R R

1991-01-01

There are no quantitative studies on the uptake of alkali into corneal tissues. To study this phenomenon, both type I collagen and bovine corneas were incubated in sodium hydroxide (NaOH) under varying conditions for periods up to 27.5 h. The sorption (absorption or adsorption) of the alkali to protein and tissue was measured as the quantity of NaOH no longer available for titration to neutrality with hydrochloric acid. Sorption was found to be dependent on the concentration of NaOH (0.01-1 N) but independent of the incubation temperature (4-35 degrees C). In whole cornea, sorption of 1 N NaOH began immediately and increased with time up to 6 h. After 6 h, sorption decreased, together with the observed degradation and solubilization of the tissue. Stripping of the corneal endothelium alone or of the endothelium and epithelium increased sorption in a similar manner when compared to whole corneas for periods up to 4 h. These observations are compatible with ionic and nonionic bonding of hydroxide ions to collagen (including that of the cornea) and the subsequent release of hydroxide ions during hydrolysis of the protein itself. Indirect evidence also suggests the inclusion of quantities of unbound hydroxide ions in hydrated gels of glycosaminoglycans. It is proposed that in a chemical burn of the cornea, alkali is both stored in the tissue (by sorption) and reacted with it (by hydrolysis), without any net consumption of alkali taking place.

Intrastromal Injection of China Painting Ink in Corneas of Male Rabbits: Clinical and Histological Study.

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Alsmman Hassan, Alahmady Hamad; Abd Elhaliem Soliman, Nesreen Gamal-Eldeen

2016-01-01

Background. Many patients with corneal opacity or complicated cataract in blind eye ask for cosmoses. In this study we tried to investigate the staining of corneas of male rabbits by Rotring China painting ink and to study the histological changes. Method. 10 eyes of 10 male Baladi Egyptian rabbits were injected (0.1 mL) intrastromally in the cornea by the use of China painting ink (Rotring Tinta China) through insulin syringe (27-gauge needle) by single injection; clinical follow-up is for 6 months and lastly the rabbits were scarified and the stained eyes were enucleated for histological analysis. Results. Clinically the stain was stable in color and distribution in corneas with no major complications. Histological results of the stained rabbit corneas showed blackish pigmentation in the corneal stroma without any inflammatory cellular infiltration. Some fibroblast cells had pigment granules in their cytoplasm in the adjacent layers. Conclusion. Corneal staining by China painting ink is effective and safe in staining of male rabbits cornea; however further study in human corneas with longer follow-up period is advisable.

Intrastromal Injection of China Painting Ink in Corneas of Male Rabbits: Clinical and Histological Study

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Alahmady Hamad Alsmman Hassan

2016-01-01

Full Text Available Background. Many patients with corneal opacity or complicated cataract in blind eye ask for cosmoses. In this study we tried to investigate the staining of corneas of male rabbits by Rotring China painting ink and to study the histological changes. Method. 10 eyes of 10 male Baladi Egyptian rabbits were injected (0.1 mL intrastromally in the cornea by the use of China painting ink (Rotring Tinta China through insulin syringe (27-gauge needle by single injection; clinical follow-up is for 6 months and lastly the rabbits were scarified and the stained eyes were enucleated for histological analysis. Results. Clinically the stain was stable in color and distribution in corneas with no major complications. Histological results of the stained rabbit corneas showed blackish pigmentation in the corneal stroma without any inflammatory cellular infiltration. Some fibroblast cells had pigment granules in their cytoplasm in the adjacent layers. Conclusion. Corneal staining by China painting ink is effective and safe in staining of male rabbits cornea; however further study in human corneas with longer follow-up period is advisable.

Hydration and transparency of the rabbit cornea irradiated with UVB-doses of 0.25 J/cm(2) and 0.5 J/cm(2) compared with equivalent UVB radiation exposure reaching the human cornea from sunlight.

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Cejka, Cestmír; Ardan, Taras; Sirc, Jakub; Michálek, Jiří; Beneš, Jiří; Brůnová, Blanka; Rosina, Jozef

2011-07-01

Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm(2) or 0.5 J/cm(2) for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm(2) and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm(2). The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm(2). Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection.

Lectin receptors in the human cornea.

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Holmes, M J; Mannis, M J; Lund, J; Jacobs, L

Five different biotin labeled lectins, Concanavalin-A (Con A), wheat germ agglutinin (WGA), Ricinus communis agglutinin I (RCA1), Ulex europaeus agglutinin (UEA1), and soybean agglutinin (SBA) were used to study lectin receptors on formalin-fixed paraffin embedded human corneas. Con A stained the cytoplasm, cell, and nuclear membranes of the epithelial cells and stained the stroma diffusely. WGA stained the superficial epithelial cells, the epithelial cell membranes, and the keratocytes of the stroma. SBA did not react with any of the corneal layers. RCA1 heavily stained the keratocytes but did not stain the epithelium. UEA1 lightly stained the epithelial cell cytoplasm and interstitial stroma. All staining reactions could be abolished by omission of the lectin or by the use of the appropriate inhibitory sugar. The lectin binding patterns reported here provide a means for further investigation of carbohydrate structures in the human cornea in both normal and disease states.

Elastic microfibril distribution in the cornea: Differences between normal and keratoconic stroma.

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White, Tomas L; Lewis, Philip N; Young, Robert D; Kitazawa, Koji; Inatomi, Tsutomu; Kinoshita, Shigeru; Meek, Keith M

2017-06-01

The optical and biomechanical properties of the cornea are largely governed by the collagen-rich stroma, a layer that represents approximately 90% of the total thickness. Within the stroma, the specific arrangement of superimposed lamellae provides the tissue with tensile strength, whilst the spatial arrangement of individual collagen fibrils within the lamellae confers transparency. In keratoconus, this precise stromal arrangement is lost, resulting in ectasia and visual impairment. In the normal cornea, we previously characterised the three-dimensional arrangement of an elastic fiber network spanning the posterior stroma from limbus-to-limbus. In the peripheral cornea/limbus there are elastin-containing sheets or broad fibers, most of which become microfibril bundles (MBs) with little or no elastin component when reaching the central cornea. The purpose of the current study was to compare this network with the elastic fiber distribution in post-surgical keratoconic corneal buttons, using serial block face scanning electron microscopy and transmission electron microscopy. We have demonstrated that the MB distribution is very different in keratoconus. MBs are absent from a region of stroma anterior to Descemet's membrane, an area that is densely populated in normal cornea, whilst being concentrated below the epithelium, an area in which they are absent in normal cornea. We contend that these latter microfibrils are produced as a biomechanical response to provide additional strength to the anterior stroma in order to prevent tissue rupture at the apex of the cone. A lack of MBs anterior to Descemet's membrane in keratoconus would alter the biomechanical properties of the tissue, potentially contributing to the pathogenesis of the disease. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Cytogenetic damage and postradiation restoration of eye cornea epithelium of Rodentia characterizing by different radiosensitivity

International Nuclear Information System (INIS)

Popova, M.F.; Bulyakova, N.V.

1983-01-01

Intensity of beam damage and reparation of eye cornea epithelium of animals inhabiting under different conditions and differing by radiosensitivity has been studied. Mice differing by high radiosensitivity have the hardest cytogenetic damage. Cornea epithelium of bank voles is more radiostable than that of mice. The most negligible damages of cornea epithelium is observed in Mongolian sandwort despite the fact that their total radiation stability is lower than that of bank voles. High protective-restoring properties of eye cornea epithelium of Mongolian sandwort are explained by the structure of epithelium cells diffe-- ring by a large number of cytoplasm

In vivo confocal Raman spectroscopy of the human cornea.

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Bauer, N J; Hendrikse, F; March, W F

1999-07-01

To investigate the feasibility of a confocal Raman spectroscopic technique for the noninvasive assessment of corneal hydration in vivo in two legally blind subjects. A laser beam (632.8 nm; 15 mJ) was maintained on the cornea by using a microscope objective lens (x25 magnification, NA = 0.5, f = 10 mm) both for focusing the incident light as well as collecting the Raman backscattered light, in a 180 degrees backscatter configuration. An optical fiber, acting as the confocal pinhole for elimination of light from out-of-focus places, was coupled to a spectrometer that dispersed the collected light onto a sensitive array detector for rapid spectral data acquisition over a range from 2,890 to 3,590/cm(-1). Raman spectra were recorded from the anterior 100-150 microm of the cornea over a period before and after topical application of a mild dehydrating solution. The ratio between the amplitudes of the signals at 3,400/cm(-1) (OH-vibrational mode of water) and 2,940/cm(-1) (CH-vibrational mode of proteins) was used as a measure for corneal hydration. High signal-to-noise ratio (SNR = 25) Raman spectra were obtained from the human corneas by using 15 mJ of laser light energy. Qualitative changes in the hydration of the anteriormost part of the corneas could be observed as a result of the dehydrating agent. With adequate improvements in system safety, confocal Raman spectroscopy could potentially be applied clinically as a noninvasive tool for the assessment of corneal hydration in vivo.

Experimental corneal calcification, hydration and /sup 45/Ca uptake in rabbit corneas incubated in vitro

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Obenberger, J [Ceskoslovenska Akademie Ved, Prague. Oftalmologicka Laborator; Dobiasova, M; Babicky, A [Ceskoslovenska Akademie Ved, Prague. Isotopova Laborator Biologickych Ustavu

1974-07-01

Experimental corneal calcification could easily be produced by a combination of corneal injury (perfusion of the anterior chamber of the eye with a solution of potassium permanganate) amd dihydrotachysterol (DHT) treatment. Rabbit corneas with induced calcification as well as corneas of three additional groups of rabbits, i.e. those treated with permanganate or DHT only and control animals were incubated for two hours in a medium containing /sup 45/Ca. An increased uptake of /sup 45/Ca into the cornea was found in the group of rabbits receiving DHT only. Potassium cyanide added to the incubation medium did not affect corneal hydration nor the final activity of the incubated corneas. (auth)

Differentially expressed wound healing-related microRNAs in the human diabetic cornea.

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Funari, Vincent A; Winkler, Michael; Brown, Jordan; Dimitrijevich, Slobodan D; Ljubimov, Alexander V; Saghizadeh, Mehrnoosh

2013-01-01

MicroRNAs are powerful gene expression regulators, but their corneal repertoire and potential changes in corneal diseases remain unknown. Our purpose was to identify miRNAs altered in the human diabetic cornea by microarray analysis, and to examine their effects on wound healing in cultured telomerase-immortalized human corneal epithelial cells (HCEC) in vitro. Total RNA was extracted from age-matched human autopsy normal (n=6) and diabetic (n=6) central corneas, Flash Tag end-labeled, and hybridized to Affymetrix® GeneChip® miRNA Arrays. Select miRNAs associated with diabetic cornea were validated by quantitative RT-PCR (Q-PCR) and by in situ hybridization (ISH) in independent samples. HCEC were transfected with human pre-miR™miRNA precursors (h-miR) or their inhibitors (antagomirs) using Lipofectamine 2000. Confluent transfected cultures were scratch-wounded with P200 pipette tip. Wound closure was monitored by digital photography. Expression of signaling proteins was detected by immunostaining and Western blot. Using microarrays, 29 miRNAs were identified as differentially expressed in diabetic samples. Two miRNA candidates showing the highest fold increased in expression in the diabetic cornea were confirmed by Q-PCR and further characterized. HCEC transfection with h-miR-146a or h-miR-424 significantly retarded wound closure, but their respective antagomirs significantly enhanced wound healing vs. controls. Cells treated with h-miR-146a or h-miR-424 had decreased p-p38 and p-EGFR staining, but these increased over control levels close to the wound edge upon antagomir treatment. In conclusion, several miRNAs with increased expression in human diabetic central corneas were found. Two such miRNAs inhibited cultured corneal epithelial cell wound healing. Dysregulation of miRNA expression in human diabetic cornea may be an important mediator of abnormal wound healing.

Differentially expressed wound healing-related microRNAs in the human diabetic cornea.

Directory of Open Access Journals (Sweden)

Vincent A Funari

Full Text Available MicroRNAs are powerful gene expression regulators, but their corneal repertoire and potential changes in corneal diseases remain unknown. Our purpose was to identify miRNAs altered in the human diabetic cornea by microarray analysis, and to examine their effects on wound healing in cultured telomerase-immortalized human corneal epithelial cells (HCEC in vitro. Total RNA was extracted from age-matched human autopsy normal (n=6 and diabetic (n=6 central corneas, Flash Tag end-labeled, and hybridized to Affymetrix® GeneChip® miRNA Arrays. Select miRNAs associated with diabetic cornea were validated by quantitative RT-PCR (Q-PCR and by in situ hybridization (ISH in independent samples. HCEC were transfected with human pre-miR™miRNA precursors (h-miR or their inhibitors (antagomirs using Lipofectamine 2000. Confluent transfected cultures were scratch-wounded with P200 pipette tip. Wound closure was monitored by digital photography. Expression of signaling proteins was detected by immunostaining and Western blot. Using microarrays, 29 miRNAs were identified as differentially expressed in diabetic samples. Two miRNA candidates showing the highest fold increased in expression in the diabetic cornea were confirmed by Q-PCR and further characterized. HCEC transfection with h-miR-146a or h-miR-424 significantly retarded wound closure, but their respective antagomirs significantly enhanced wound healing vs. controls. Cells treated with h-miR-146a or h-miR-424 had decreased p-p38 and p-EGFR staining, but these increased over control levels close to the wound edge upon antagomir treatment. In conclusion, several miRNAs with increased expression in human diabetic central corneas were found. Two such miRNAs inhibited cultured corneal epithelial cell wound healing. Dysregulation of miRNA expression in human diabetic cornea may be an important mediator of abnormal wound healing.

Ex vivo rabbit cornea diffusion studies with a soluble insert of moxifloxacin.

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Sebastián-Morelló, María; Calatayud-Pascual, María Aracely; Rodilla, Vicent; Balaguer-Fernández, Cristina; López-Castellano, Alicia

2018-02-01

The objective of this research was to develop and evaluate an ocular insert for the controlled drug delivery of moxifloxacin which could perhaps be used in the treatment of corneal keratitis or even bacterial endophthalmitis. We have evaluated the ex vivo ocular diffusion of moxifloxacin through rabbit cornea, both fresh and preserved under different conditions. Histological studies were also carried out. Subsequently, drug matrix inserts were prepared using bioadhesive polymers. The inserts were evaluated for their physicochemical parameters. Ophthalmic ex vivo permeation of moxifloxacin was carried out with the most promising insert. The formulate insert was thin and provided higher ocular diffusion than commercial formulations. Ocular diffusion studies revealed significant differences between fresh and frozen corneas. Histological examinations also showed differences in the thickness of stroma between fresh and frozen corneas. The ophthalmic insert we have developed allows a larger quantity of moxifloxacin to permeate through the cornea than existing commercial formulations of the drug. Ocular delivery of moxifloxacin with this insert could be a new approach for the treatment of eye diseases.

Inflammation Modulatory Protein TSG-6 for Chemical Injuries to the Cornea

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2017-10-01

AWARD NUMBER: W81XWH-14-1-0495 TITLE: Inflammation Modulatory Protein TSG-6 for Chemical Injuries to the Cornea PRINCIPAL INVESTIGATOR...2017 4. TITLE AND SUBTITLE Inflammation Modulatory Protein TSG-6 for Chemical Injuries to the Cornea Infla I Inflammation Modulatory Protein TSG-6...anti-inflammatory protein , TSG-6, which has a novel mechanism of action. Chemical injuries of the eye are difficult to treat, and may lead to

High-resolution, label-free two-photon imaging of diseased human corneas

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Batista, Ana; Breunig, Hans Georg; König, Aisada; Schindele, Andreas; Hager, Tobias; Seitz, Berthold; König, Karsten

2018-03-01

The diagnosis of corneal diseases may be improved by monitoring the metabolism of cells and the structural organization of the stroma using two-photon imaging (TPI). We used TPI to assess the differences between nonpathological (NP) human corneas and corneas diagnosed with either keratoconus, Acanthamoeba keratitis, or stromal corneal scars. Images were acquired using a custom-built five-dimensional laser-scanning microscope with a broadband sub-15 femtosecond near-infrared pulsed excitation laser and a 16-channel photomultiplier tube detector in combination with a time-correlated single photon counting module. Morphological alterations of epithelial cells were observed for all pathologies. Moreover, diseased corneas showed alterations to the cells' metabolism that were revealed using the NAD(P)H free to protein-bound ratios. The mean autofluorescence lifetime of the stroma and the organization of the collagen fibers were also significantly altered due to the pathologies. We demonstrate that TPI can be used to distinguish between NP and diseased human corneas, based not only on alterations of the cells' morphology, which can also be evaluated using current clinical devices, but on additional morphological and functional features such as the organization of the stroma and the cells' metabolism. Therefore, TPI could become an efficient tool for diagnosing corneal diseases and better understanding the biological processes of the diseases.

Oxygen transport through soft contact lens and cornea: Lens characterization and metabolic modeling

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Chhabra, Mahendra

The human cornea requires oxygen to sustain metabolic processes critical for its normal functioning. Any restriction to corneal oxygen supply from the external environment (e.g., by wearing a low oxygen-permeability contact lens) can lead to hypoxia, which may cause corneal edema (swelling), limbal hyperemia, neovascularization, and corneal acidosis. The need for adequate oxygen to the cornea is a major driving force for research and development of hypertransmissible soft contact lenses (SCLs). Currently, there is no standard technique for measuring oxygen permeability (Dk) of hypertransmissible silicone-hydrogel SCLs. In this work, an electrochemistry-based polarographic apparatus was designed, built, and operated to measure oxygen permeability in hypertransmissible SCLs. Unlike conventional methods where a range of lens thickness is needed for determining oxygen permeabilities of SCLs, this apparatus requires only a single lens thickness. The single-lens permeameter provides a reliable, efficient, and economic tool for measuring oxygen permeabilities of commercial hypertransmissible SCLs. The single-lens permeameter measures not only the product Dk, but, following modification, it measures separately diffusivity, D, and solubility, k, of oxygen in hypertransmissible SCLs. These properties are critical for designing better lens materials that ensure sufficient oxygen supply to the cornea. Metabolism of oxygen in the cornea is influenced by contact-lens-induced hypoxia, diseases such as diabetes, surgery, and drug treatment, Thus, estimation of the in-vivo corneal oxygen consumption rate is essential for gauging adequate oxygen supply to the cornea. Therefore, we have developed an unsteady-state reactive-diffusion model for the cornea-contact-lens system to determine in-vivo human corneal oxygen-consumption rate. Finally, a metabolic model was developed to determine the relation between contact-lens oxygen transmissibility (Dk/L) and corneal oxygen deficiency. A

Morphology of endothelial cells from different regions of the equine cornea

OpenAIRE

Faganello, Cláudia Skilhan; Silva, Vanessa Ruiz Moura da; Andrade, Maria Cristina Caldart de; Carissimi, André Silva; Pigatto, João Antonio Tadeu

2016-01-01

ABSTRACT: The objective of this study was to evaluate the morphology of different regions of the equine cornea using optical microscopy. Both healthy eyes of eight horses, male or female, of different ages were evaluated. Corneas were stained with alizarin red vital dye and subsequently examined and photographed using optical microscopy. Corneal endothelial morphology of central, superior, inferior, temporal and nasal areas was assessed. One hundred endothelial cells from each corneal area we...

The use of human cornea organotypic cultures to study herpes simplex virus type 1 (HSV-1)-induced inflammation.

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Drevets, Peter; Chucair-Elliott, Ana; Shrestha, Priyadarsini; Jinkins, Jeremy; Karamichos, Dimitrios; Carr, Daniel J J

2015-10-01

To determine the utility of human organotypic cornea cultures as a model to study herpes simplex virus type 1 (HSV-1)-induced inflammation and neovascularization. Human organotypic cornea cultures were established from corneas with an intact limbus that were retrieved from donated whole globes. One cornea culture was infected with HSV-1 (10(4) plaque-forming units), while the other cornea from the same donor was mock-infected. Supernatants were collected at intervals post-culture with and without infection to determine viral titer (by plaque assay) and pro-angiogenic and proinflammatory cytokine concentration by suspension array analysis. In some experiments, the cultured corneas were collected and evaluated for HSV-1 antigens by immunohistochemical means. Another set of experiments measured susceptibility of human three-dimensional cornea fibroblast constructs, in the presence and absence of TGF-β1, to HSV-1 infection in terms of viral replication and the inflammatory response to infection as a comparison to the organotypic cornea cultures. Organotypic cornea cultures and three-dimensional fibroblast constructs exhibited varying degrees of susceptibility to HSV-1. Fibroblast constructs were more susceptible to infection in terms of infectious virus recovered in a shorter period of time. There were changes in the levels of select pro-angiogenic or proinflammatory cytokines that were dictated as much by the cultures producing them as by whether they were infected with HSV-1 or treated with TGF-β1. Organotypic cornea and three-dimensional fibroblast cultures are likely useful for the identification and short-term study of novel antiviral compounds and virus replication, but are limited in the study of the local immune response to infection.

Cornea procurement, preservation and transplantation

International Nuclear Information System (INIS)

Hudson Silva

1999-01-01

Our experience on this subject is 40 years and we have seen the developments everywhere during this total period. Cornea procurement has been an unsurmountable problem in a large number of countries, mostly due to social and cultural reasons. The requirements for a simple eye bank to manage the supply for a local hospital are minimal. What is the most important is the donor base. In Sri Lanka nurtured in the traditions of Theravada Buddhism the donor base was easy to prepare. We had no difficulties with Christians and Hindus. For Muslims there are Fatwas in favour of donating eyes. But we always found them to be a reluctant group. But in predominantly Muslim countries, it is imperative that social workers should take up this issue, so those thousands may be helped. In all areas where attempts are made to procure comeas, it is important to have a day-and-night service available at short notice to collect any eyes offered. A trained technician with sterilised instruments to obtain eyes and blood sample must be available at a convenient location preferably in a large hospital. Even in places where the supply is infrequent, it is essential to have the readily-sterilised instruments to proceed to a donor site at short notice. To get eyes, general publicity in mass media alone is not sufficient. Such publicity makes people aware of the need for donor eyes and where a technician/doctor is available. What is more important is to canvass personally after a person has died For this purpose trained social workers may be employed, or the technician can do the motivation, as we do in Sri Lanka. Once eyes are removed, it is essential to pay careful attention to the appearance of the cadaver. It should not (and need not) cause any deformity as such event has a profound negative effect on the campaign. Many different preservation methods have been used over the years. Mc Carey-Kaufmann (MK) medium has been the standard for many years, and gives a life span of 4-5 days. The formula

Efficacious and safe tissue-selective controlled gene therapy approaches for the cornea.

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Rajiv R Mohan

2011-04-01

Full Text Available Untargeted and uncontrolled gene delivery is a major cause of gene therapy failure. This study aimed to define efficient and safe tissue-selective targeted gene therapy approaches for delivering genes into keratocytes of the cornea in vivo using a normal or diseased rabbit model. New Zealand White rabbits, adeno-associated virus serotype 5 (AAV5, and a minimally invasive hair-dryer based vector-delivery technique were used. Fifty microliters of AAV5 titer (6.5×10(12 vg/ml expressing green fluorescent protein gene (GFP was topically applied onto normal or diseased (fibrotic or neovascularized rabbit corneas for 2-minutes with a custom vector-delivery technique. Corneal fibrosis and neovascularization in rabbit eyes were induced with photorefractive keratectomy using excimer laser and VEGF (630 ng using micropocket assay, respectively. Slit-lamp biomicroscopy and immunocytochemistry were used to confirm fibrosis and neovascularization in rabbit corneas. The levels, location and duration of delivered-GFP gene expression in the rabbit stroma were measured with immunocytochemistry and/or western blotting. Slot-blot measured delivered-GFP gene copy number. Confocal microscopy performed in whole-mounts of cornea and thick corneal sections determined geometric and spatial localization of delivered-GFP in three-dimensional arrangement. AAV5 toxicity and safety were evaluated with clinical eye exam, stereomicroscopy, slit-lamp biomicroscopy, and H&E staining. A single 2-minute AAV5 topical application via custom delivery-technique efficiently and selectively transduced keratocytes in the anterior stroma of normal and diseased rabbit corneas as evident from immunocytochemistry and confocal microscopy. Transgene expression was first detected at day 3, peaked at day 7, and was maintained up to 16 weeks (longest tested time point. Clinical and slit-lamp eye examination in live rabbits and H&E staining did not reveal any significant changes between AAV5

Corneal decompensation following filtering surgery with the Ex-PRESS® mini glaucoma shunt device

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Tojo N

2015-03-01

Full Text Available Naoki Tojo, Atsushi Hayashi, Akio Miyakoshi Department of Ophthalmology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan Purpose: To report a case of corneal decompensation due to the Ex-PRESS® mini glaucoma shunt device (Ex-PRESS.Patient and methods: A 75-year-old man had pseudoexfoliation glaucoma in his right eye. He underwent filtration surgery with Ex-PRESS. His intraocular pressure was 7 mmHg after 9 months.Results: We observed partial decompensation of the corneal endothelium adjacent to the filtering bleb. Specular microscopy revealed a marked decrease in the endothelial cell density at the center of the cornea.Conclusion: Anterior segment optical coherence tomography is very useful for evaluating corneal edema and the position of Ex-PRESS. It is important to follow up with an examination of the corneal endothelial cells. Keywords: Ex-PRESS, bullous keratopathy, trabeculectomy, complication, cornea 

Why Does the Healthy Cornea Resist Pseudomonas aeruginosa Infection?

Science.gov (United States)

Evans, David J.; Fleiszig, Suzanne M. J.

2013-01-01

Purpose To provide our perspective on why the cornea is resistant to infection based on our research results with Pseudomonas aeruginosa. Perspective We focus on our current understanding of the interplay between bacteria, tear fluid and the corneal epithelium that determine health as the usual outcome, and propose a theoretical model for how contact lens wear might change those interactions to enable susceptibility to P. aeruginosa infection. Methods Use of “null-infection” in vivo models, cultured human corneal epithelial cells, contact lens-wearing animal models, and bacterial genetics help to elucidate mechanisms by which P. aeruginosa survive at the ocular surface, adheres, and traverses multilayered corneal epithelia. These models also help elucidate the molecular mechanisms of corneal epithelial innate defense. Results and Discussion Tear fluid and the corneal epithelium combine to make a formidable defense against P. aeruginosa infection of the cornea. Part of that defense involves the expression of antimicrobials such as β-defensins, the cathelicidin LL-37, cytokeratin-derived antimicrobial peptides, and RNase7. Immunomodulators such as SP-D and ST2 also contribute. Innate defenses of the cornea depend in part on MyD88, a key adaptor protein of TLR and IL-1R signaling, but the basal lamina represents the final barrier to bacterial penetration. Overcoming these defenses involves P. aeruginosa adaptation, expression of the type three secretion system, proteases, and P. aeruginosa biofilm formation on contact lenses. Conclusion After more than two decades of research focused on understanding how contact lens wear predisposes to P. aeruginosa infection, our working hypothesis places blame for microbial keratitis on bacterial adaptation to ocular surface defenses, combined with changes to the biochemistry of the corneal surface caused by trapping bacteria and tear fluid against the cornea under the lens. PMID:23601656

Anterior segment optical coherence tomography for evaluation of cornea and ocular surface

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Mittanamalli S Sridhar

2018-01-01

Full Text Available Current corneal assessment technologies make the process of corneal evaluation extremely fast and simple. Several devices and technologies allow to explore and manage patients better. Optical coherence tomography (OCT technology has evolved over the years, and hence a detailed evaluation of anterior segment (AS structures such as cornea, conjunctiva, tear meniscus, anterior chamber, iris, and crystalline lens has been possible in a noncontact and safe procedure. The purpose of this special issue is to present and update in the evaluation of cornea and ocular surface, and this paper reviews a description of the AS-OCT, presenting the technology and common clinical uses of OCT in the management of diseases involving cornea and ocular surface to provide an updated information of the clinical recommendations of this technique in eye care practice.

[The value of methods for morphofunctional analysis of cornea in cataract surgery].

Science.gov (United States)

Borodina, N B; Kobzova, M V; Musaeva, G M

2011-01-01

The characteristics of morphofunctional status of cornea after extracapsular cataract extraction and phakoemulsification with IOL implantation (30 and 58 operations respectively) were analyzed in detail using up-to-date diagnostic techniques. The results of examination using developed algorithm including study of light transmission, refraction and protective function of cornea show advantage of microinvasive ultrasound technique of cataract surgery in terms of minimal impact on corneal structure, optical and biomechanical characteristics.

Optical coherent tomography measurements of the diffusion rate of water and drugs in an isolated and whole cornea

International Nuclear Information System (INIS)

Larin, Kirill V; Ghosn, M G

2006-01-01

The passive diffusion of drugs through the epithelial surfaces of an eye (the most widespread method for medical treatment of various diseases) is considered. The permeability of water and drugs through rabbit cornea was measured in the isolated cornea (separate from an eye) and in the whole cornea. The permeability coefficients of water and dexamethasone were estimated by the method of optical coherence tomography (OCT). Because multiple photon scattering introduces noise and distortions to the OCT signal, measurements were performed at depths up to 500 μm where most likely single scattering of light occurs in cornea. It is shown that the permeability coefficients in the isolated and whole cornea strongly differ from each other. For example, the water permeability in the isolated and whole cornea is (7.09±0.12)x10 -5 and (1.71±0.51)x10 -5 cm s -1 , respectively. (special issue devoted to multiple radiation scattering in random media)

In vivo laser confocal microscopy findings of a cornea with osteogenesis imperfecta

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Kobayashi A

2014-02-01

Full Text Available Akira Kobayashi, Tomomi Higashide, Hideaki Yokogawa, Natsuko Yamazaki, Toshinori Masaki, Kazuhisa Sugiyama Department of Ophthalmology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan Objective: To report the in vivo laser confocal microscopy findings of a cornea with osteogenesis imperfecta (OI with special attention to the abnormality of Bowman's layer and sub-Bowman's fibrous structures (K-structures. Patients and methods: Two patients (67-year-old male and his 26-year-old son with OI type I were included in this study. Slit lamp biomicroscopic and in vivo laser confocal microscopic examinations were performed for both patients. Central corneal thickness and central endothelial cell density were also measured. Results: Although the corneas looked clear with normal endothelial density for both eyes in both patients, they were quite thin (386 µm oculus dexter (OD (the right eye and 384 µm oculus sinister (OS (the left eye in the father and 430 µm OD and 425 µm OS in the son. In both patients, slit lamp biomicroscopic and in vivo laser confocal microscopic examination showed similar results. Anterior corneal mosaics produced by rubbing the eyelid under fluorescein were completely absent in both eyes. In vivo laser confocal microscopy revealed an absent or atrophic Bowman's layer; a trace of a presumed Bowman's layer and/or basement membrane was barely visible with high intensity. Additionally, K-structures were completely absent in both eyes. Conclusion: The absence of K-structures and fluorescein anterior corneal mosaics strongly suggested an abnormality of Bowman's layer in these OI patients. Keywords: osteogenesis imperfecta, K-structure, confocal microscopy, Bowman's layer

Crosslinked collagen–gelatin–hyaluronic acid biomimetic film for cornea tissue engineering applications

International Nuclear Information System (INIS)

Liu, Yang; Ren, Li; Wang, Yingjun

2013-01-01

Cornea disease may lead to blindness and keratoplasty is considered as an effective treatment method. However, there is a severe shortage of donor corneas worldwide. This paper presents the crosslinked collagen (Col)–gelatin (Gel)–hyaluronic acid (HA) films developed by making use of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as the crosslinker. The test results on the physical and biological properties indicate that the CGH631 film (the mass ratio of Col:Gel:HA = 6:3:1) has appropriate optical performance, hydrophilicity and mechanical properties. The diffusion properties of the CGH631 film to NaCl and tryptophan are also satisfactory and the measured data are 2.43 × 10 −6 cm 2 /s and 7.97 × 10 −7 cm 2 /s, respectively. In addition, cell viability studies demonstrate that the CGH631 film has good biocompatibility, on which human corneal epithelial cells attached and proliferated well. This biocompatible film may have potential use in cornea tissue engineering. - Highlights: ► Crosslinked collagen–gelatin–hyaluronic acid films were fabricated in this study. ► The film had appropriate physical properties. ► Diffusion coefficient of the film was comparable with the human cornea. ► HCEC viability studies confirmed the biocompatibility of the film.

Wavelength-dependent ultraviolet induction of cyclobutane pyrimidine dimers in the human cornea.

Science.gov (United States)

Mallet, Justin D; Rochette, Patrick J

2013-08-01

Exposition to ultraviolet (UV) light is involved in the initiation and the progression of skin cancer. The genotoxicity of UV light is mainly attributed to the induction of cyclobutane pyrimidine dimers (CPDs), the most abundant DNA damage generated by all UV types (UVA, B and C). The human cornea is also exposed to the harmful UV radiations, but no UV-related neoplasm has been reported in this ocular structure. The probability that a specific DNA damage leads to a mutation and eventually to cellular transformation is influenced by its formation frequency. To shed light on the genotoxic effect of sunlight in the human eye, we have analyzed CPD induction in the cornea and the iris following irradiation of ex vivo human eyes with UVA, B or C. The extent of CPD induction was used to establish the penetrance of the different UV types in the human cornea. We show that UVB- and UVC-induced CPDs are concentrated in the corneal epithelium and do not penetrate deeply beyond this corneal layer. On the other hand, UVA wavelengths penetrate deeper and induce CPDs in the entire cornea and in the first layers of the iris. Taken together, our results are undoubtedly an important step towards better understanding the consequences of UV exposure to the human eye.

Computational modeling of drug transport across the in vitro cornea.

Science.gov (United States)

Pak, Joseph; Chen, Z J; Sun, Kay; Przekwas, Andrzej; Walenga, Ross; Fan, Jianghong

2018-01-01

A novel quasi-3D (Q3D) modeling approach was developed to model networks of one dimensional structures like tubes and vessels common in human anatomy such as vascular and lymphatic systems, neural networks, and respiratory airways. Instead of a branching network of the same tissue type, this approach was extended to model an interconnected stack of different corneal tissue layers with membrane junction conditions assigned between the tissues. The multi-laminate structure of the cornea presents a unique barrier design and opportunity for investigation using Q3D modeling. A Q3D model of an in vitro rabbit cornea was created to simulate the drug transport across the cornea, accounting for transcellular and paracellular pathways of passive and convective drug transport as well as physicochemistry of lipophilic partitioning and protein binding. Lipophilic Rhodamine B and hydrophilic fluorescein were used as drug analogs. The model predictions for both hydrophilic and lipophilic tracers were able to match the experimental measurements along with the sharp discontinuities at the epithelium-stroma and stroma-endothelium interfaces. This new modeling approach was successfully applied towards pharmacokinetic modeling for use in topical ophthalmic drug design. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of single and repeated UVB radiation on rabbit cornea.

Science.gov (United States)

Fris, Miroslav; Tessem, May-Britt; Cejková, Jitka; Midelfart, Anna

2006-12-01

Cumulative effect of ultraviolet radiation (UVR) is an important aspect of UV corneal damage. The purpose of this study was to apply high resolution magic angle spinning proton nuclear magnetic resonance (HR-MAS 1H NMR) spectroscopy to evaluate the effect of single and repeated UV radiation exposure of the same overall dose on the rabbit cornea. Corneal surfaces of 24 normal rabbit eyes were examined for the effects of UVB exposure (312 nm). In the first group (UVB1), animals were irradiated with a single dose (3.12 J/cm2; 21 min) of UVB radiation. The animals in the second group (UVB2) were irradiated three times for 7 min every other day (dose of 1.04 J/cm2; days 1, 3, 5) to give the same overall dose (3.12 J/cm2). The third group served as an untreated control group. One day after the last irradiation, the animals were sacrificed, and the corneas were removed and frozen. HR-MAS 1H NMR spectra from intact corneas were obtained. Special grouping patterns among the tissue samples and the relative percentage changes in particular metabolite concentrations were evaluated using modern statistical methods (multivariate analysis, one-way ANOVA). The metabolic profile of both groups of UVB-irradiated samples was significantly different from the control corneas. Substantial decreases in taurine, hypo-taurine and choline-derivatives concentrations and substantial elevation in glucose and betaine levels were observed following the UVR exposure. There was no significant difference between the effect of a single and repeated UVB irradiation of the same overall dose. For the first time, the effects of single and repeated UVR doses on the metabolic profile of the rabbit cornea were analysed and compared. The combination of HR-MAS 1H NMR spectroscopy and modern statistical methods (multivariate analysis, one-way ANOVA) proved suitable to assess the overall view of the metabolic alterations in the rabbit corneal tissue following UVB radiation exposure.

Thermodynamic measurement after cooling the cornea with intact epithelium and lid manipulation.

Science.gov (United States)

de Ortueta, Diego; Magnago, Thomas; Arba-Mosquera, Samuel

2015-01-01

To characterize the rate of change of ocular surface temperature (OST) under lid manipulation after cooling the intact cornea with balanced salt solution (BSS). In a patient for refractive surgery, prior to the ablation, the temperature of the cornea was continuously recorded with a high speed infrared (350Hz) camera. Two millilitre of chilled BSS with a temperature of 8.6°Celsius (°C) was instilled for about 3s. Using exponential functions, the three contributions have been determined, subjacent corneal layers, environment, and chilled BSS. The mean temperature of the cornea preoperatively was 34.5°C. After applying the chilled BSS the temperature decreased about 14°C down to an OST of 20°C and the time needed afterwards to get the normal (OST) temperature of about 30°C was 40s. Due to the inserted speculum and missing blink, OST did not reach the original OST of 34.5°C and faded at about 32.5°C. According to our best fitted model, absolute value of each contributing component was 31.4°C (subjacent corneal layers), 26.8°C (environment) and 8.6°C (BSS). Applying chilled BSS to the cornea quickly reduces the temperature of the cornea with a thermal relaxation time of 3s and a amplitude decrease of 8.6°C. This together with a relaxation time of 7s for subjacent corneal layers, and 184s for environment after instillation of BSS combined with a well-controlled environment provides a period of 40s of corneal temperature below baseline, which may be of clinical benefit when applying chilled BSS immediately before or immediately after ablation. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

[Results of an internet-based survey amongst members of the German Ophthalmological Society concerning postmortem cornea donation].

Science.gov (United States)

Uhlig, C E; Promesberger, J; Hirschfeld, G; Koch, R; Reinhard, T; Seitz, B

2012-12-01

Analysis of willingness for postmortem cornea donation by professionals in ophthalmology and their motives in favor of or against donation. 3887 members of the German Ophthalmological Society received an anonymous questionnaire concerning sociodemographic background, physical health, experiences with organ explantation and their former engagement and motives concerning organ and cornea donation. 722 of the questionnaires were partially and 533 completely answered with an average willingness for cornea donation of 79.4%. Significant parameters for cornea donation were gender, former experience with organ explantation, ophthalmological health and fear of false diagnosis of brain death, worse medical treatment or organ commercialization. Of the participants 53.9% suggested the internet as a favorite source of information in this matter. The factors which had a significant impact on cornea donation in this survey seem to be mainly a result of insufficient information. Detailed information regarding this topic should preferentially be presented on internet pages of professional societies and could probably increase donation approval of DOG members.

Crosslinked collagen-gelatin-hyaluronic acid biomimetic film for cornea tissue engineering applications

Energy Technology Data Exchange (ETDEWEB)

Liu, Yang; Ren, Li, E-mail: psliren@scut.edu.cn; Wang, Yingjun, E-mail: imwangyj@163.com

2013-01-01

Cornea disease may lead to blindness and keratoplasty is considered as an effective treatment method. However, there is a severe shortage of donor corneas worldwide. This paper presents the crosslinked collagen (Col)-gelatin (Gel)-hyaluronic acid (HA) films developed by making use of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as the crosslinker. The test results on the physical and biological properties indicate that the CGH631 film (the mass ratio of Col:Gel:HA = 6:3:1) has appropriate optical performance, hydrophilicity and mechanical properties. The diffusion properties of the CGH631 film to NaCl and tryptophan are also satisfactory and the measured data are 2.43 Multiplication-Sign 10{sup -6} cm{sup 2}/s and 7.97 Multiplication-Sign 10{sup -7} cm{sup 2}/s, respectively. In addition, cell viability studies demonstrate that the CGH631 film has good biocompatibility, on which human corneal epithelial cells attached and proliferated well. This biocompatible film may have potential use in cornea tissue engineering. - Highlights: Black-Right-Pointing-Pointer Crosslinked collagen-gelatin-hyaluronic acid films were fabricated in this study. Black-Right-Pointing-Pointer The film had appropriate physical properties. Black-Right-Pointing-Pointer Diffusion coefficient of the film was comparable with the human cornea. Black-Right-Pointing-Pointer HCEC viability studies confirmed the biocompatibility of the film.

Mesothelial proteins are expressed in the human cornea

Czech Academy of Sciences Publication Activity Database

Jirsová, K.; Neuwirth, Aleš; Kalašová, S.; Veselá, V.; Merjava, S.

2010-01-01

Roč. 91, č. 5 (2010), s. 623-629 ISSN 0014-4835 Institutional research plan: CEZ:AV0Z50520514 Keywords : cornea * HBME-1 (Hector Battifora mesothelial cell-1) protein * calbindin 2 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.817, year: 2010

Sphere-forming cells from peripheral cornea demonstrate a wound-healing response to injury.

Science.gov (United States)

Huang, Stephanie U; Yoon, Jinny J; Ismail, Salim; McGhee, Jennifer J; Sherwin, Trevor

2015-11-01

The cornea is the initial refractive interface of the eye. Its transparency is critical for clear vision and is maintained by stem cells which also act to repair injury inflicted by external insults, such as chemical and thermal burns. Damage to the epithelium compromises its clarity and can reduce or eliminate the stem cell population, diminishing the ability for self-repair. This condition has been termed "limbal stem cell deficiency"; severe cases can lead to corneal blindness. Sphere-forming cells isolated from peripheral cornea are a potential source of stem and progenitor cells for corneal repair. When provided with appropriate substrate, these spheres have the ability to adhere and for cells to migrate outwards akin to that of their natural environment. Direct compression injury and remote scratch injury experiments were conducted on the sphere cells to gauge their wound healing capacity. Measures of proliferation, differentiation, and migration were assessed by immunohistochemical detection of EdU incorporation, α-smooth muscle actin expression and confocal image analysis, respectively. Both modes of injury were observed to draw responses from the spheres indicating wound healing processes. Direct wounding induced a rapid, but transient increase in expression of α-SMA, a marker of corneal myofibroblasts, followed by a proliferative and increasing migratory response. The spheres were observed to respond to remote injury as entire units, with no directional response seen for targeted repair over the scratch injury area. These results give strength to the future use of these peripheral corneal spheres as transplantable units for the regeneration of corneal tissue. © 2015 International Federation for Cell Biology.

Xanthelasmata, arcus corneae, and ischaemic vascular disease and death in general population: prospective cohort study

DEFF Research Database (Denmark)

Christoffersen, Mette; Frikke-Schmidt, Ruth; Schnohr, Peter

2011-01-01

To test the hypothesis that xanthelasmata and arcus corneae, individually and combined, predict risk of ischaemic vascular disease and death in the general population.......To test the hypothesis that xanthelasmata and arcus corneae, individually and combined, predict risk of ischaemic vascular disease and death in the general population....

Differential expression and processing of transforming growth factor beta induced protein (TGFBIp) in the normal human cornea during postnatal development and aging

DEFF Research Database (Denmark)

Karring, Henrik; Runager, Kasper; Valnickova, Zuzana

2010-01-01

Transforming growth factor beta induced protein (TGFBIp, also named keratoepithelin) is an extracellular matrix protein abundant in the cornea. The purpose of this study was to determine the expression and processing of TGFBIp in the normal human cornea during postnatal development and aging...... trimming events from the N-terminus of mature TGFBIp generate TGFBIp isoforms which form a similar "zig-zag" pattern when separated by 2-D polyacrylamide gel electrophoresis (PAGE). This study shows that in humans TGFBIp is more abundant in mature corneas than in the developing cornea...... and that the processing of TGFBIp changes during postnatal development of the cornea. In addition, TGFBIp appears to be degraded in a highly orchestrated manner in the normal human cornea with the resulting C-terminal fragments being retained in the cornea. The age-related changes in the expression and processing...

In vivo 3D measurement of moxifloxacin and gatifloxacin distributions in the mouse cornea using multiphoton microscopy

Science.gov (United States)

Lee, Seunghun; Lee, Jun Ho; Park, Jin Hyoung; Yoon, Yeoreum; Chung, Wan Kyun; Tchah, Hungwon; Kim, Myoung Joon; Kim, Ki Hean

2016-05-01

Moxifloxacin and gatifloxacin are fourth-generation fluoroquinolone antibiotics used in the clinic to prevent or treat ocular infections. Their pharmacokinetics in the cornea is usually measured from extracted ocular fluids or tissues, and in vivo direct measurement is difficult. In this study multiphoton microscopy (MPM), which is a 3D optical microscopic technique based on multiphoton fluorescence, was applied to the measurement of moxifloxacin and gatifloxacin distribution in the cornea. Intrinsic multiphoton fluorescence properties of moxifloxacin and gatifloxacin were characterized, and their distributions in mouse cornea in vivo were measured by 3D MPM imaging. Both moxifloxacin and gatifloxacin had similar multiphoton spectra, while moxifloxacin had stronger fluorescence than gatifloxacin. MPM imaging of mouse cornea in vivo showed (1) moxifloxacin had good penetration through the superficial corneal epithelium, while gatifloxacin had relatively poor penetration, (2) both ophthalmic solutions had high intracellular distribution. In vivo MPM results were consistent with previous studies. This study demonstrates the feasibility of MPM as a method for in vivo direct measurement of moxifloxacin and gatifloxacin in the cornea.

Effects of genipin corneal crosslinking in rabbit corneas.

Science.gov (United States)

Avila, Marcel Y; Narvaez, Mauricio; Castañeda, Juan P

2016-07-01

To evaluate the effect of genipin, a natural crosslinking agent, in rabbit eyes. Department of Ophthalmology, Universidad Nacional de Colombia Centro de Tecnologia Oftalmica, Bogotá, Colombia. Experimental study. Ex vivo rabbit eyes (16; 8 rabbits) were treated with genipin 1.00%, 0.50%, and 0.25% for 5 minutes with a vacuum device to increase corneal permeability. Penetration was evaluated using Scheimpflug pachymetry (Pentacam). In the in vivo model (20 rabbits; 1 eye treated, 1 eye with vehicle), corneas were crosslinked with genipin as described. Corneal curvature, corneal pachymetry, and intraocular pressure (IOP) assessments as well as slitlamp examinations were performed 0, 7, 30, and 60 days after treatment. In the ex vivo model, Scheimpflug pachymetry showed deep penetration in the rabbit corneas with an increase in corneal density and a dose-dependent relationship. Corneal flattening was observed in treated eyes (mean 4.4 diopters ± 0.5 [SD]) compared with the control eyes. Pachymetry and IOP were stable in all evaluations. No eye showed toxicity in the anterior chamber or in the lens. Corneal crosslinking induced by genipin produced significant flattening of the cornea with no toxicity in rabbit eyes. This crosslinking could be useful in the treatment of corneal ectasia and in the modification of corneal curvature. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Therapeutic effect of para aminobenzoic acid (PABA) on the rat cornea administered in different ways after x-irradiation

International Nuclear Information System (INIS)

Panova, I.G.; Mel'nikova, I.I.; Stroeva, O.G.

1997-01-01

Comparative analysis of cytological state of nuclear apparatus in the mice cornea basal layer is carried out by two various method of introducing the para-aminobenzoic acid (PABA) after x-ray irradiation: 1) subcutaneous injections and 2) application of the solution on the cornea. The fact that PABA produced medicinal effect on the cornea of the irradiated mice by subcutaneous injections, shows that this action proceeds on the whole-body level

Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea.

Science.gov (United States)

Jiang, Hong; Zuo, Yi; Zhang, Li; Li, Jidong; Zhang, Aiming; Li, Yubao; Yang, Xiaochao

2014-03-01

Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.

Multiparameter thermo-mechanical OCT-based characterization of laser-induced cornea reshaping

Science.gov (United States)

Zaitsev, Vladimir Yu.; Matveyev, Alexandr L.; Matveev, Lev A.; Gelikonov, Grigory V.; Vitkin, Alex; Omelchenko, Alexander I.; Baum, Olga I.; Shabanov, Dmitry V.; Sovetsky, Alexander A.; Sobol, Emil N.

2017-02-01

Phase-sensitive optical coherence tomography (OCT) is used for visualizing dynamic and cumulative strains and corneashape changes during laser-produced tissue heating. Such non-destructive (non-ablative) cornea reshaping can be used as a basis of emerging technologies of laser vision correction. In experiments with cartilaginous samples, polyacrilamide phantoms and excised rabbit eyes we demonstrate ability of the developed OCT system to simultaneously characterize transient and cumulated strain distributions, surface displacements, scattering tissue properties and possibility of temperature estimation via thermal-expansion measurements. The proposed approach can be implemented in perspective real-time OCT systems for ensuring safety of new methods of laser reshaping of cornea.

Cholesterol biosynthesis by the cornea. Comparison of rates of sterol synthesis with accumulation during early development

International Nuclear Information System (INIS)

Cenedella, R.J.; Fleschner, C.R.

1989-01-01

The origin of the cholesterol needed by the cornea for growth and cell turnover was addressed by comparing absolute rates of sterol synthesis with rates of sterol accumulation during early development of the rabbit. Linearity of incorporation of 3 H 2 O and [ 14 C]mevalonate into digitonin-precipitable sterols with time of incubation in vitro and a lack of accumulation of 14 C in intermediates of sterol biosynthesis indicated that tritiated water can validly be used to measure rates of sterol synthesis by the cornea. The rate of sterol synthesis per unit weight of rabbit cornea was constant between 14 and 60 days of age at an average 1.03 nmol of 3 H of 3 H 2 O incorporated/mg dry cornea per 8 h. Essentially all of the synthesized cholesterol and most of the cholesterol mass was present in corneal epithelium. The cumulative sterol synthesized over the 46-day period studied exceeded the observed rate of cholesterol accumulation by sixfold. Cholesterol synthesized in excess of the growth requirement was likely used to support turnover of the epithelium which was estimated at 9 days. Removal of cholesterol from the cornea by excretion into tear fluid and clearance by high density lipoproteins are also considered

Air-pulse OCE for assessment of age-related changes in mouse cornea in vivo

International Nuclear Information System (INIS)

Li, Jiasong; Wang, Shang; Singh, M; Larin, K V; Aglyamov, S; Emelianov, S; Twa, M D

2014-01-01

We demonstrate the use of phase-stabilized swept source optical coherence elastography (PhS-SSOCE) to assess the relaxation rate of deformation created by a focused air-pulse in tissue-mimicking gelatin phantoms of various concentrations and mouse corneas of different ages in vivo. The results show that the relaxation rate can be quantified and is different for gels with varying concentrations of gelatin and mouse corneas of different ages. The results indicate that gel phantoms with higher concentrations of gelatin as well as older mouse corneas have faster relaxation rates indicating stiffer material. This non-contact and non-invasive measurement technique utilizes low surface displacement amplitude (in µm scale) for tissue excitation and, therefore, can be potentially used to study the biomechanical properties of ocular and other sensitive tissues. (letter)

Expression of multidrug resistance associated protein 5 (MRP5) on cornea and its role in drug efflux.

Science.gov (United States)

Karla, Pradeep K; Quinn, Tim L; Herndon, Betty L; Thomas, Priscilla; Pal, Dhananjay; Mitra, Ashim

2009-04-01

The purpose of this manuscript is to investigate the presence of nucleoside/nucleotide efflux transporter in cornea and to evaluate the role in ocular drug efflux. RT-PCR, immunoprecipitation followed by Western blot analysis and immunostaining were employed to establish molecular presence of multidrug resistance associated protein 5 (MRP5) on cornea. Corneal efflux by MRP5 was studied with bis(POM)-PMEA and acyclovir using rabbit and human corneal epithelial cells along with MRP5 over expressing cells (MDCKII-MRP5). Ex vivo studies using excised rabbit cornea and in vivo ocular microdialysis in male New Zealand white rabbits were used to further evaluate the role of MRP5 in conferring ocular drug resistance. RT-PCR confirms the expression of MRP5 in both rabbit and human corneal epithelial cells along with MDCKII-MRP5 cells. Immunoprecipitation followed by Western blot analysis using a rat (M511-54) monoclonal antibody that reacts with human epitope confirms the expression of MRP5 protein in human corneal epithelial cells and MDCKII-MRP5 cells. Immunostaining performed on human cornea indicates the localization of this efflux pump on both epithelium and endothelium. Efflux studies reveal that depletion of ATP decreased PMEA efflux significantly. MRP5 inhibitors also diminished PMEA and acyclovir efflux. However, depletion of glutathione did not alter efflux. MDR1 and MRP2 did not contribute to PMEA efflux. However, MRP2 is involved in acyclovir efflux while MDR1 do not participate in this process. TLC/autoradiography suggested the conversion of bis(POM)-PMEA to PMEA in rabbit and human corneal epithelial cells. Two well known antiglaucoma drugs, bimatoprost and latanoprost were rapidly effluxed by MRP5. Ex vivo study on intact rabbit corneas demonstrated accumulation of PMEA in cornea in the presence of ATP-depleting medium. In vivo ocular pharmacokinetics also revealed a significant increase in maximum aqueous humor concentration (C(max)) and area under the

Photorefractive Keratectomy (PRK) is Safe and Effective for Patients with Myopia and Thin Corneas.

Science.gov (United States)

Naderi, Mostafa; Ghadamgahi, Saeed; Jadidi, Khosrow

2016-01-01

The aim of this study was to evaluate the long-term safety and efficacy of photorefractive keratectomy (PRK) for patients with myopia and thin corneas. In this retrospective case series, we included 74 eyes of 38 patients with myopia and central corneal thickness (CCT) PRK and had a mean postoperative follow-up period of four years. The following factors were evaluated: CCT, refraction, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), ablation depth, safety and efficacy indices (i.e., the ratio of the mean postoperative BCVA to the mean preoperative BCVA, and the ratio of the mean postoperative UCVA to mean preoperative the BCVA, respectively), and evidence of corneal ectasia (based on Orbscan topography images).The patients were aged 20 - 46 years (mean ±SD age, 28.18± 6.82 years). The mean ± SD pre- and postoperative CCTwas485.92 ± 9.27 µm and 434.84 ± 20.48 µm, respectively. The mean ± SD pre- and postoperative myopia was -2.77 D ± 1.51 and -0.24 ± 0.39 D, respectively, and the mean ± SD pre- and postoperative astigmatism was -0.82 D ± 0.99 and -0.37 ± 0.37 D, respectively. The mean pre- and postoperative BCVA and postoperative UCVA was 0.011 ± 0.03 Logarithm of the Minimum Angle of Resolution (log MAR), 0.003 ± 0.01 log MAR, and 0.054 ± 0.09 log MAR, respectively. The mean ± SD ablation depth, safety index and efficacy index was 54.34 ± 16.28 µm, 0.02 ± 0.12, and 0.11 ± 0.50, respectively. Regarding the postoperative corneal clarity, 72 eyes (97.3%) had a clear cornea (grade 0) and the remaining two eyes of one patient (2.70%) had a trace haze (grade 1). There was no evidence of corneal ectasia on any of the Orbscan topography images. Thus, among patients with myopia and thin corneas (PRK seems to be acceptable in terms of both safety and efficacy 4 years after surgery, based on the stability of postoperative refraction, visual acuity, and topographic outcomes, and outcomes based on the safety and efficacy indexes.

Optics of the human cornea influence the accuracy of stereo eye-tracking methods: a simulation study

NARCIS (Netherlands)

Barsingerhorn, A.D.; Boonstra, F.N.; Goossens, H.H.L.M.

2017-01-01

Current stereo eye-tracking methods model the cornea as a sphere with one refractive surface. However, the human cornea is slightly aspheric and has two refractive surfaces. Here we used ray-tracing and the Navarro eye-model to study how these optical properties affect the accuracy of different

Effect of glaucoma tube shunt parameters on cornea endothelial cells in patients with Ahmed valve implants.

Science.gov (United States)

Koo, Euna B; Hou, Jing; Han, Ying; Keenan, Jeremy D; Stamper, Robert L; Jeng, Bennie H

2015-01-01

The aim of this study was to assess the effect of various tube parameters on corneal endothelial cell density (ECD) after insertion of Ahmed valves. Thirty-nine eyes of 33 patients with previous superotemporal (ST) Ahmed valve implantation and 20 eyes of 13 participants with previous uncomplicated phacoemulsification and intraocular lens implantation but no history of glaucoma surgery were evaluated. Various tube parameters were measured with anterior segment optical coherence tomography. ST, central, and inferonasal (IN) ECD and pachymetry were measured. Endothelial cell loss and corneal thickness in the ST cornea was compared with those in the IN cornea. The mean age of the operated patients was 58 ± 22 years, and the mean time since glaucoma surgery was 2.5 ± 2.6 years. Thirty-two of the 39 study eyes were pseudophakic. The ECD was significantly lower in the ST endothelium than in the IN endothelium in eyes with glaucoma tube surgery (P < 0.001), although this relative reduction in ST ECD was not greater than that seen in pseudophakic control eyes (P = 0.16). In univariate analysis, tube angle relative to the cornea and distance from the tip of the tube to the cornea were significant risk factors for decreased ST endothelial cell loss when assessed relative to the IN ECD (P = 0.01 and P = 0.02, respectively). In multivariate analysis, only the distance of the tube tip to the cornea remained significantly associated with ST endothelial cell loss. Although this was a retrospective study with inherent limitations, tubes that are closer to the cornea seem to lead to increased loss of adjacent endothelial cells.

Tracing the fate of limbal epithelial progenitor cells in the murine cornea.

Science.gov (United States)

Di Girolamo, N; Bobba, S; Raviraj, V; Delic, N C; Slapetova, I; Nicovich, P R; Halliday, G M; Wakefield, D; Whan, R; Lyons, J G

2015-01-01

Stem cell (SC) division, deployment, and differentiation are processes that contribute to corneal epithelial renewal. Until now studying the destiny of these cells in a living mammal has not been possible. However, the advent of inducible multicolor genetic tagging and powerful imaging technologies has rendered this achievable in the translucent and readily accessible murine cornea. K14CreER(T2)-Confetti mice that harbor two copies of the Brainbow 2.1 cassette, yielding up to 10 colors from the stochastic recombination of fluorescent proteins, were used to monitor K-14(+) progenitor cell dynamics within the corneal epithelium in live animals. Multicolored columns of cells emerged from the basal limbal epithelium as they expanded and migrated linearly at a rate of 10.8 µm/day toward the central cornea. Moreover, the permanent expression of fluorophores, passed on from progenitor to progeny, assisted in discriminating individual clones as spectrally distinct streaks containing more than 1,000 cells within the illuminated area. The centripetal clonal expansion is suggestive that a single progenitor cell is responsible for maintaining a narrow corridor of corneal epithelial cells. Our data are in agreement with the limbus as the repository for SC as opposed to SC being distributed throughout the central cornea. This is the first report describing stem/progenitor cell fate determination in the murine cornea using multicolor genetic tracing. This model represents a powerful new resource to monitor SC kinetics and fate choice under homeostatic conditions, and may assist in assessing clonal evolution during corneal development, aging, wound-healing, disease, and following transplantation. © 2014 AlphaMed Press.

Atmospheric-Pressure Cold Plasma Induces Transcriptional Changes in Ex Vivo Human Corneas.

Directory of Open Access Journals (Sweden)

Umberto Rosani

Full Text Available Atmospheric pressure cold plasma (APCP might be considered a novel tool for tissue disinfection in medicine since the active chemical species produced by low plasma doses, generated by ionizing helium gas in air, induces reactive oxygen species (ROS that kill microorganisms without substantially affecting human cells.In this study, we evaluated morphological and functional changes in human corneas exposed for 2 minutes (min to APCP and tested if the antioxidant n-acetyl l-cysteine (NAC was able to inhibit or prevent damage and cell death.Immunohistochemistry and western blotting analyses of corneal tissues collected at 6 hours (h post-APCP treatment demonstrated no morphological tissue changes, but a transient increased expression of OGG1 glycosylase that returned to control levels in 24 h. Transcriptome sequencing and quantitative real time PCR performed on different corneas revealed in the treated corneas many differentially expressed genes: namely, 256 and 304 genes showing expression changes greater than ± 2 folds in the absence and presence of NAC, respectively. At 6 h post-treatment, the most over-expressed gene categories suggested an active or enhanced cell functioning, with only a minority of genes specifically concerning oxidative DNA damage and repair showing slight over-expression values (<2 folds. Moreover, time-related expression analysis of eight genes up-regulated in the APCP-treated corneas overall demonstrated the return to control expression levels after 24 h.These findings of transient oxidative stress accompanied by wide-range transcriptome adjustments support the further development of APCP as an ocular disinfectant.

Optics of the human cornea influence the accuracy of stereo eye-tracking methods: a simulation study.

Science.gov (United States)

Barsingerhorn, A D; Boonstra, F N; Goossens, H H L M

2017-02-01

Current stereo eye-tracking methods model the cornea as a sphere with one refractive surface. However, the human cornea is slightly aspheric and has two refractive surfaces. Here we used ray-tracing and the Navarro eye-model to study how these optical properties affect the accuracy of different stereo eye-tracking methods. We found that pupil size, gaze direction and head position all influence the reconstruction of gaze. Resulting errors range between ± 1.0 degrees at best. This shows that stereo eye-tracking may be an option if reliable calibration is not possible, but the applied eye-model should account for the actual optics of the cornea.

Optical properties of an anterior lamellar human cornea model based on fibrin-agarose

Science.gov (United States)

Ionescu, Ana M.; Cardona, Juan de la Cruz; Ghinea, Razvan; Garzón, Ingrid; González-Andrades, Miguel; Alaminos, Miguel; Pérez, Maria del Mar

2017-08-01

The optical evaluation carried out using the Inverse Adding-Doubling (IAD) method to determine the scattering and the absorption coefficients of the bioengineered human corneal stromas showed that this type of artificial biomaterials shared many similarities with native control cornea after four weeks of development in culture. Their absorption and reduced scattering coefficients values were higher than the ones of the control cornea, but their spectral behaviors of both coefficients were similar. Time of development in culture was an influencing factor on the results.

Collagen organization in the chicken cornea and structural alterations in the retinopathy, globe enlarged (rge) phenotype--an X-ray diffraction study.

Science.gov (United States)

Boote, Craig; Hayes, Sally; Jones, Simon; Quantock, Andrew J; Hocking, Paul M; Inglehearn, Chris F; Ali, Manir; Meek, Keith M

2008-01-01

An investigation into the collagenous structure of the mature avian cornea is presented. Wide-angle X-ray diffraction is employed to assess collagen organization in 9-month-old chicken corneas. The central 2-4mm corneal region features a preponderance of fibrils directed along the superior-inferior and nasal-temporal orthogonal meridians. More peripherally the orientation of fibrils alters in favor of a predominantly tangential arrangement. The chicken cornea appears to be circumscribed by an annulus of fibrils that extends into the limbus. The natural arrangement of collagen in the chicken cornea is discussed in relation to corneal shape and the mechanical requirements of avian corneal accommodation. Equivalent data are also presented from age-matched blind chickens affected with the retinopathy, globe enlarged (rge) mutation, characterized by an abnormally thick and flat cornea. The data indicate considerable realignment and redistribution of collagen lamellae in the peripheral rge cornea. In contrast to normal chickens, no obvious tangential collagen alignment was evident in the periphery of rge corneas. In mammals, the presence of a limbal fibril annulus is believed to be important in corneal shape preservation. We postulate that corneal flattening in rge chickens may be related to biomechanical changes brought about by an alteration in collagen arrangement at the corneal periphery.

Computer driven optical keratometer and method of evaluating the shape of the cornea

Science.gov (United States)

Baroth, Edmund C. (Inventor); Mouneimme, Samih A. (Inventor)

1994-01-01

An apparatus and method for measuring the shape of the cornea utilize only one reticle to generate a pattern of rings projected onto the surface of a subject's eye. The reflected pattern is focused onto an imaging device such as a video camera and a computer compares the reflected pattern with a reference pattern stored in the computer's memory. The differences between the reflected and stored patterns are used to calculate the deformation of the cornea which may be useful for pre-and post-operative evaluation of the eye by surgeons.

[Riboflavin photoprotection with cross-linking effect in photorefractive ablation of the cornea].

Science.gov (United States)

Kornilovskiy, I M; Sultanova, A I; Burtsev, A A

2016-01-01

Photorefractive ablation is inevitably accompanied by oxidative stress of the cornea and weakening of its biomechanical and photoprotective properties. To validate the expediency of riboflavin use in photorefractive ablation for photoprotection of the cornea and cross-linking. The effects of riboflavin use in photorefractive ablation was first studied in a series of in vitro and in vivo experiments performed on 56 eyes of 28 rabbits, and then on 232 eyes of 142 patients with different degrees of myopia. Biomechanical testing of corneal samples was performed with Zwick/RoellВZ 2.5/TN1S tensile-testing machine. Transepithelial photorefractive keratectomy (TransPRK) and femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) were performed on Wavelight-Allegretto200, MEL-80, and WaveLight-EX500 excimer laser systems and also VisuMax and WaveLight-FS200 femtosecond lasers. For preliminary examinations, an appropriate set of diagnostic tools was used. In vivo experiments have proved that, in the absence of conservative therapy, riboflavin is able to produce both photoprotective and cross-linking effects to the cornea. Corneal syndrome was thus reduced and re-epithelialization after TransPRK accelerated. Biomechanical testing of corneal samples revealed an increase in tolerated load from 12.9±1.4 N to 18.3±1.2 N (p=0.0002) and tensile strength from 8.6±1.7 MPa to 12.4±1.7 MPa (p=0.007). Clinical studies conducted in a group of patients with mild to moderate myopia have also confirmed the photoprotective effect of riboflavin at months 1-12 after TransPRK. There were no significant differences in uncorrected visual acuity (ranged from 0.80±0.16 to 0.85±0.15) and corrected visual acuity at baseline (0.83±0.14). Evaluation of the optical and refractive effect achieved after Femto-LASIK with riboflavin photoprotection in the fellow eye has shown that this technique is not inferior to the traditional one as to its refractive accuracy, but provides better

Intra-Ocular Pressure Measurement in a Patient with a Thin, Thick or Abnormal Cornea.

Science.gov (United States)

Clement, Colin I; Parker, Douglas G A; Goldberg, Ivan

2016-01-01

Accurate measurement of intra-ocular pressure is a fundamental component of the ocular examination. The most common method of measuring IOP is by Goldmann applanation tonometry, the accuracy of which is influenced by the thickness and biomechanical properties of the cornea. Algorithms devised to correct for corneal thickness to estimate IOP oversimplify the effects of corneal biomechanics. The viscous and elastic properties of the cornea influence IOP measurements in unpredictable ways, a finding borne out in studies of patients with inherently abnormal and surgically altered corneal biomechanics. Dynamic contour tonometry, rebound tonometry and the ocular response analyzer provide useful alternatives to GAT in patients with abnormal corneas, such as those who have undergone laser vision correction or keratoplasty. This article reviews the various methods of intra-ocular pressure measurement available to the clinician and the ways in which their utility is influenced by variations in corneal thickness and biomechanics.

Excimer laser ablation of the cornea

Science.gov (United States)

Pettit, George H.; Ediger, Marwood N.; Weiblinger, Richard P.

1995-03-01

Pulsed ultraviolet laser ablation is being extensively investigated clinically to reshape the optical surface of the eye and correct vision defects. Current knowledge of the laser/tissue interaction and the present state of the clinical evaluation are reviewed. In addition, the principal findings of internal Food and Drug Administration research are described in some detail, including a risk assessment of the laser-induced-fluorescence and measurement of the nonlinear optical properties of cornea during the intense UV irradiation. Finally, a survey is presented of the alternative laser technologies being explored for this ophthalmic application.

Low-dose radiation effects on the evolution of chronic dystrophical processes in cornea and clouding of crystalline lens

International Nuclear Information System (INIS)

Gajdaj, Yu.V.; Gajdaj, V.M.

1993-01-01

Low-dose radiation effects on the course of chronic dystrophical processes in cornea and the dynamics of crystalline lens clouding of involution age genesis are investigated in the patients participated in Chernobyl accident response. Examples of the concrete pathological cases are considered. It was stated that the above dose effects led to exacerbation of the chronic slack dystrophical processes in cornea and intensification of the development of cornea primary dystrophy. In a number of cases the intensification of development of crystalline lens clouding takes place resulted in the cataract for 2-3 years

Colocalization of Galectin-3 With CD147 Is Associated With Increased Gelatinolytic Activity in Ulcerating Human Corneas.

Science.gov (United States)

Cruzat, Andrea; Gonzalez-Andrades, Miguel; Mauris, Jérôme; AbuSamra, Dina B; Chidambaram, Preethi; Kenyon, Kenneth R; Chodosh, James; Dohlman, Claes H; Argüeso, Pablo

2018-01-01

Galectin-3 is a carbohydrate-binding protein known to promote expression of matrix metalloproteinases, a hallmark of ulceration, through interaction with the extracellular matrix metalloproteinase inducer CD147. The aim of this study was to investigate the distribution of galectin-3 in corneas of patients with ulcerative keratitis and to determine its relationship to CD147 and the presence of gelatinolytic activity. This was an observational case series involving donor tissue from 13 patients with active corneal ulceration and 6 control corneas. Fixed-frozen sections of the corneas were processed to localize galectin-3 and CD147 by immunofluorescence microscopy. Gelatinolytic activity was detected by in situ zymography. Tissue from patients with active corneal ulceration showed a greater galectin-3 immunoreactivity in basal epithelia and stroma compared with controls. Immunofluorescence grading scores revealed increased colocalization of galectin-3 and CD147 in corneal ulcers at the epithelial-stromal junction and within fibroblasts. Quantitative analysis using the Manders' colocalization coefficient demonstrated significant overlap in corneas from patients with ulcerative keratitis (M1 = 0.29; M2 = 0.22) as opposed to control corneas (M1 = 0.01, P < 0.01; M2 = 0.02, P < 0.05). In these experiments, there was a significant positive correlation between the degree of galectin-3 and CD147 colocalization and the presence of gelatinolytic activity. Our results indicate that concomitant stimulation and colocalization of galectin-3 with CD147 are associated with increased gelatinolytic activity in the actively ulcerating human cornea and suggest a mechanism by which galectin-3 may contribute to the degradation of extracellular matrix proteins during ulceration.

Autologous conjunctiva transplantation with stem cells on edge of cornea for recurrent pterygium

Directory of Open Access Journals (Sweden)

Yun Wang

2013-10-01

Full Text Available AIM: To observe the clinical effectiveness and practicality the autologous conjunctiva transplantation with stem cells on edge of cornea for recurrent pterygium.METHODS: Of the 53 recurrent pterygium patients(57 eyes, after all pathological tissues were removed, underwent the autologous conjunctiva transplantation with stem cells on edge of cornea which were locked above conjunctival transplantation of the operated eye.RESULTS: Postopretive follow-up was 1-12 months for all 57 eyes, of which 3 eyes(5%relapsed. The corneoscleral autolysis was occurred in one eye and surgery treatment was conducted. Corneal wounds were healing and transplantations survived well for the remaining 53 patients without obvious surgical marks. Cure rate was 93%.CONCLUSION: Autologous conjunctiva transplantation with stem cells on edge of cornea for recurrent pterygium can meet the aesthetic requirements of the some patients, with the advantages of obtaining material easily, faster wound healing, lower postoperative recurrence rate, meeting the aesthetic needs of some patients and improving postoperative results. Thus, it is an ideal surgery and is worthy of applying on primary hospital.

The Naïve Murine Cornea as a Model System to Identify Novel Endogenous Regulators of Lymphangiogenesis: TRAIL and rtPA.

Science.gov (United States)

Regenfuß, Birgit; Dreisow, Marie-Luise; Hos, Deniz; Masli, Sharmila; Bock, Felix; Cursiefen, Claus

2015-06-01

In the murine cornea, which is an established model for analyzing pathologic lymphatic vessel growth, phenotypic heterogeneity of the endogenous lymphatic vessels in the limbus of the cornea was previously described. In this study, the cornea of BALB/c, C57BL/6, and FVB mice with different limbal lymphangiogenic phenotypes was analyzed to identify novel candidates potentially influencing lymphatic vessel growth. Pathway specific expression analysis of the cornea was performed to identify novel candidate genes. Corneal protein expression of the respective candidates was analyzed by fluorescent immunohistochemistry. The effect of the candidates on proliferation of human dermal lymphatic endothelial cells (HDLECs) was analyzed by BrdU proliferation ELISA. Thirteen genes were differentially regulated in corneas of mouse strains with more endogenous limbal lymphatic vessels (high-lymphangiogenic) (C57BL/6) compared to mouse strains with less endogenous limbal lymphatic vessels (low-lymphangiogenic) (BALB/c, FVB). Two candidates, Tumor necrosis factor (ligand) superfamily member 10 (Tnfsf10/Trail) and Plasminogen activator, tissue (Plat/tPA) were expressed in the cornea of BALB/c and C57BL/6 mice on the protein level. In vitro, Trail and recombinant tPA inhibited the proliferation of human dermal lymphatic endothelial cells. Molecular analysis of the naive cornea in mouse strains with different limbal lymphatic phenotypes is a valuable model to identify novel endogenous regulators of lymphangiogenesis.

Stabilization diagrams using operational modal analysis and sliding filters

DEFF Research Database (Denmark)

Olsen, Peter; Juul, Martin Ørum Ørhem; Tarpø, Marius Glindtvad

2017-01-01

This paper presents a filtering technique for doing effective operational modal analysis. The result of the filtering method is construction of stabilization diagram that clearly separates physical poles from spurious noise poles needed for unbiased fitting. A band pass filter is moved slowly over...

Experience of Comamonas acidovorans keratitis with delayed onset and treatment response in immunocompromised cornea.

Science.gov (United States)

Lee, Sang Mok; Kim, Mee Kum; Lee, Jae Lim; Wee, Won Ryang; Lee, Jin Hak

2008-03-01

To report 2 cases of Comamonas acidovorans keratitis in immunocompromised cornea. A complete review of the medical records of the two cases of Comamonas acidovorans keratitis. We found some similarities in clinical courses of two cases. Both of them showed development of keratitis during the management with corticosteroids, delayed onset, slow response to antibiotics, and relatively less affected corneal epithelium. Comamonas acidovorans is known as a less virulent organism. However it can cause an indolent infection that responds slowly even to adequate antibiotics therapy in immunocompromised corneas.

Intracellular Position of Centrioles and the Direction of Homeostatic Epithelial Cell Movements in the Mouse Cornea.

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Silverman, Erika; Zhao, Jin; Merriam, John C; Nagasaki, Takayuki

2017-02-01

Corneal epithelial cells exhibit continuous centripetal movements at a rate of about 30 µm per day, but neither the driving force nor the mechanism that determines the direction of movements is known. To facilitate the investigation of homeostatic cell movement, we examined if the intracellular position of a centriole can be used as a directional marker of epithelial cell movements in the mouse cornea. A direction of cell movements was estimated in fixed specimens from a pattern of underlying subepithelial nerve fibers. Intracellular position of centrioles was determined by gamma-tubulin immunohistology and plotted in a narrow strip along the entire diameter of a cornea from limbus to limbus. When we determined the position of centrioles in the peripheral cornea where cell movements proceed generally along a radial path, about 55% of basal epithelial cells contained a centriole in the front half of a cell. However, in the central cornea where cells exhibit a spiral pattern of movements, centrioles were distributed randomly. These results suggest that centrioles tend to be positioned toward the direction of movement in corneal basal epithelial cells when they are moving centripetally at a steady rate.

A comparison study of Riboflavin/UV-A and Rose-Bengal/Green light cross-linking of the rabbit corneas using optical coherence elastography

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Li, Jiasong; Singh, Manmohan; Han, Zhaolong; Vantipalli, Srilatha; Liu, Chih-Hao; Wu, Chen; Raghunathan, Raksha; Kazemi, Tina; Twa, Michael D.; Larin, Kirill V.

2016-03-01

The biomechanical properties of the cornea are critical factors which determine its health and subsequent visual acuity. Keratoconus is a structural degeneration of the cornea which can diminish vision quality. Riboflavin/UV-A corneal collagen cross-linking (UV-CXL) is an emerging treatment that increases the stiffness of the cornea and improves its ability to resist further degeneration. While UV-CXL has shown great promise for effective therapy of the keratoconus, there are concerns associated with the UV irradiation, such as keratocyte cytotoxicity. Rose-bengal/green light corneal collagen cross-linking (RGX) has been proposed as an alternative to UV-CXL. Because of the high absorbance of the rose-bengal dye at green wavelengths, the treatment time is significantly shorter than with UV-CXL. Moreover, because green light is used in lieu of UV irradiation, there are no cytotoxic side-effects. In this study, noncontact optical coherence elastography (OCE) was used to compare the outcomes of UV-CXL and RGX treatment in rabbit cornea. Low-amplitude (micrometer scale) elastic waves were induced by a focused air-pulse loading system. The elastic wave propagation was then imaged by a phase-stabilized swept source OCE (PhS-SSOCE) system. The changes in the viscoelasticity of the corneas were quantified by a previously developed modified Rayleigh Lamb frequency model. The depth-resolved micro-scale phase-velocity distribution in the cornea was used to reveal the depth-wise heterogeneity before and after both cross-linking techniques. Our results show that UV-CXL and RGX increased the stiffness of the corneas by ~54% and ~5% while reducing the viscosity by ~42% and ~17%, respectively. The depth-wise phase velocities showed that UV-CXL affected the anterior ~1/3 of the corneas, while RGX only affected the anterior ~1/7 of the corneas.

Effects of acetylcholine (ACh) and norepinephrine (NE) on phosphatidylinositol 4,5-bisphosphate (PIP2) turnover in rabbit cornea

International Nuclear Information System (INIS)

Akhtar, R.A.; Abdel-Latif, A.A.

1986-01-01

Muscarinic cholinergic and α 1 -adrenergic agonists provoke hydrolysis of PIP 2 into diacylglycerol (DG) and inositol trisphosphate (IP 3 ) in a wide variety of tissue. Recently, IP 3 has been shown to mobilize Ca 2+ from ER in several permeabilized tissue preparations. Although rabbit cornea is enriched in ACh and NE, the physiological function of these neurotransmitters is unclear. The present studies were initiated to determine the effects of cholinergic and adrenergic agonists on PIP 2 turnover in the cornea. Addition of ACh or NE (50 μM each) to the 32 P-labeled corneas for 10 min decreased the radioactivity in PIP 2 by 33 and 36%, and increased the radioactivity in phosphatidic acid by 72 and 52%, respectively. When the corneas were labeled with myo-[ 3 H]inositol, ACh and NE increased the accumulation of IP 3 by 92 and 48%, respectively. The effects of ACh and NE on phospholipid labeling and IP 3 accumulation were specifically inhibited by atropine (10 μM) and prazosin (10 μM), respectively. The data suggest the presence of muscarinic cholinergic and α 1 -adrenergic receptors in the rabbit cornea. Furthermore, activation of these receptors leads to cleavage of PIP 2 into DG and IP 3 which may function as second messengers in this tissue

Taurine effect on cytogenetic lesions in the cornea of mice exposed to 9 Gev proton irradiation

International Nuclear Information System (INIS)

Vorozhtsova, S.V.; Yartsev, E.I.

1989-01-01

Possibilities of preventive measures and treatment of cytogenetic injuries in the mice cornea, subjected to proton irradiation at 9 Gev were studied. Taurine containing solution (TCS) was used as a radiomodifying agent. It is shown that TCS application enables to decrease aberrant mitoses level in cornea epithelium cells of mice. Antiactinic effect of the above agent is determined by its considerable action on mitotic delay

Second harmonic generation microscopy of the living human cornea

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Artal, Pablo; Ávila, Francisco; Bueno, Juan

2018-02-01

Second Harmonic Generation (SHG) microscopy provides high-resolution structural imaging of the corneal stroma without the need of labelling techniques. This powerful tool has never been applied to living human eyes so far. Here, we present a new compact SHG microscope specifically developed to image the structural organization of the corneal lamellae in living healthy human volunteers. The research prototype incorporates a long-working distance dry objective that allows non-contact three-dimensional SHG imaging of the cornea. Safety assessment and effectiveness of the system were firstly tested in ex-vivo fresh eyes. The maximum average power of the used illumination laser was 20 mW, more than 10 times below the maximum permissible exposure (according to ANSI Z136.1-2000). The instrument was successfully employed to obtain non-contact and non-invasive SHG of the living human eye within well-established light safety limits. This represents the first recording of in vivo SHG images of the human cornea using a compact multiphoton microscope. This might become an important tool in Ophthalmology for early diagnosis and tracking ocular pathologies.

Descemet's stripping-automated endothelial keratoplasty for symptomatic thioridazine deposits in the cornea

Directory of Open Access Journals (Sweden)

Masoumeh Mohebbi

2017-01-01

Full Text Available The aim of this study was to use Descemet's Stripping-automated Endothelial Keratoplasty (DSAEK as a novel treatment to remove thioridazine corneal deposits. A 53-year-old female presented with a 3-month history of visual loss and glare. She had been taking thioridazine (100 mg/day for 1 year for a psychiatric disorder. Dense yellowish-brown deposits had developed in the posterior stroma. Thioridazine was discontinued, and she was switched to fluoxetine. One year after discontinuation of thioridazine, her symptoms and signs did not resolve. Standard DSAEK was performed on her left eye. Two weeks after DSAEK, an anterior subcapsular cataract was detected in the same eye. Phacoemulsification and intraocular lens implantation were performed after 3 months. The left cornea became completely clear after DSAEK, and the patient's best-corrected visual acuity improved from 20/40 to 20/20 at 1 month after cataract surgery. All-visual symptoms such as glare and halos improved postoperatively. We suggest that DSAEK can be used as a novel treatment to reduce vision problems caused by thioridazine-induced corneal deposits.

Quantifying the effects of UV-A/riboflavin crosslinking on the elastic anisotropy and hysteresis of the porcine cornea by noncontact optical coherence elastography

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Singh, Manmohan; Li, Jiasong; Raghunathan, Raksha; Han, Zhaolong; Nair, Achuth; Liu, Chih-Hao; Aglyamov, Salavat R.; Twa, Michael D.; Larin, Kirill V.

2017-02-01

The collagen fibril orientation of the cornea can provide critical information about cornea tissue health because diseases such as keratoconus and therapeutic interventions such as UV-A/riboflavin corneal collagen crosslinking (CXL) can alter the ultrastructural arrangement of collagen fibrils. Here, we quantify the elastic anisotropy and hysteresis of in situ porcine corneas as a function of intraocular pressure (IOP) with noncontact optical coherence elastography. Moreover, the effects of UV-A riboflavin corneal collagen crosslinking on the elastic anisotropy and hysteresis were evaluated. The propagation of an air-pulse induced elastic wave was imaged at stepped meridional angles by a home built phasestabilized swept source OCE system. The stiffness of the cornea was translated from the velocity of the wave, and the elastic anisotropy was quantified by modifying the planar anisotropy coefficient. As the IOP increased, the stiffness of the corneas increased from 18 kPa at 15 mmHg IOP to 120 kPa at 30 mmHg IOP. While there was a measureable hysteresis, it was not significant. After CXL, the Young's modulus of the corneas significantly increased from 18 kPa to 44 kPa at 15 mmHg IOP. The mechanical anisotropy also increased significantly from 10 a.u. in the untreated corneas to 23 a.u. in the CXL treated corneas, 15 mmHg IOP. However, CXL did not change the elastic anisotropic orientation, and the mechanical anisotropic hysteresis was not significant after CXL.

Expression profiles of aquaporins in rat conjunctiva, cornea, lacrimal gland and Meibomian gland.

Science.gov (United States)

Yu, Dongfang; Thelin, William R; Randell, Scott H; Boucher, Richard C

2012-10-01

The aim of the study was to elucidate aquaporin (AQP) family member mRNA expression and protein expression/localization in the rat lacrimal functional unit. The mRNA expression of all rat AQPs (AQP0-9, 11-12) in palpebral, fornical, and bulbar conjunctiva, cornea, lacrimal gland, and Meibomian gland was measured by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) and real time RT-PCR. Antibodies against AQP1, 3, 4, 5, 9, and 11 were used in Western blotting and immunohistochemistry to determine protein expression and distribution. Our study demonstrated characteristic AQP expression profiles in rat ocular tissues. AQP1, 3, 4, 5, 8, 9, 11, and 12 mRNA were detected in conjunctiva. AQP0, 1, 2, 3, 4, 5, 6, 11, and 12 mRNA were expressed in cornea. AQP0, 1, 2, 3, 4, 5, 7, 8, and 11 mRNA were detected in lacrimal gland. AQP1, 3, 4, 5, 7, 8, 9, 11, and 12 mRNA were identified in Meibomian gland. By Western blot, AQP1, 3, 5, and 11 were detected in conjunctiva; AQP1, 3, 5, and 11 were identified in cornea; AQP1, 3, 4, 5, and 11 were detected in lacrimal gland; and AQP1, 3, 4, 5, 9, and 11 were present in Meibomian gland. Immunohistochemistry localized AQPs to distinct sites in the various tissues. This study rigorously analyzed AQPs expression and localization in rat conjunctiva, cornea, lacrimal gland, and Meibomian gland tissues. Our findings provide a comprehensive platform for further investigation into the physiological or pathophysiological relevance of AQPs in ocular surface. Copyright © 2012 Elsevier Ltd. All rights reserved.

Image defog algorithm based on open close filter and gradient domain recursive bilateral filter

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Liu, Daqian; Liu, Wanjun; Zhao, Qingguo; Fei, Bowen

2017-11-01

To solve the problems of fuzzy details, color distortion, low brightness of the image obtained by the dark channel prior defog algorithm, an image defog algorithm based on open close filter and gradient domain recursive bilateral filter, referred to as OCRBF, was put forward. The algorithm named OCRBF firstly makes use of weighted quad tree to obtain more accurate the global atmospheric value, then exploits multiple-structure element morphological open and close filter towards the minimum channel map to obtain a rough scattering map by dark channel prior, makes use of variogram to correct the transmittance map,and uses gradient domain recursive bilateral filter for the smooth operation, finally gets recovery images by image degradation model, and makes contrast adjustment to get bright, clear and no fog image. A large number of experimental results show that the proposed defog method in this paper can be good to remove the fog , recover color and definition of the fog image containing close range image, image perspective, the image including the bright areas very well, compared with other image defog algorithms,obtain more clear and natural fog free images with details of higher visibility, what's more, the relationship between the time complexity of SIDA algorithm and the number of image pixels is a linear correlation.

Virtual experiment of optical spatial filtering in Matlab environment

Science.gov (United States)

Ji, Yunjing; Wang, Chunyong; Song, Yang; Lai, Jiancheng; Wang, Qinghua; Qi, Jing; Shen, Zhonghua

2017-08-01

The principle of spatial filtering experiment has been introduced, and the computer simulation platform with graphical user interface (GUI) has been made out in Matlab environment. Using it various filtering processes for different input image or different filtering purpose will be completed accurately, and filtering effect can be observed clearly with adjusting experimental parameters. The physical nature of the optical spatial filtering can be showed vividly, and so experimental teaching effect will be promoted.

Study of the protective properties of paraaminobenzoic acid for cornea of adult rats under X-radiation

International Nuclear Information System (INIS)

Stroeva, O.G.; Panova, I.G.; Mel'nikova, I.I.

1997-01-01

To test the efficiency of para-aminobenzoic acid (PABA) as a radioprotector for mammal tissues the protective properties of PABA for cornea of adult rats-males exposed to single whole-body irradiation were studied. X-irradiation was performed using RUM-17 facility at the dose of 5 Gy (dose rate is of 0.886 Gy/min). Results obtained prove reliably radioprotective and therapeutic effect of PABA on the cornea cells [ru

Damage Threshold of In Vivo Rabbit Cornea by 2 micron Laser Irradiation

National Research Council Canada - National Science Library

Chen, Bo; Oliver, Jeffery; Dutta, Soumak; Rylander, III, Grady H; Thomsen, Sharon L; Welch, Ashley J

2007-01-01

To support refinement of the Maximum Permissible Exposure (MPE) safety limits, a series of experiments were conducted in vivo on Dutch Belted rabbit corneas to determine corneal minimum visible lesion thresholds...

Dexamethasone Drug Eluting Nanowafers Control Inflammation in Alkali-Burned Corneas Associated With Dry Eye

Science.gov (United States)

Bian, Fang; Shin, Crystal S.; Wang, Changjun; Pflugfelder, Stephen C.; Acharya, Ghanashyam; De Paiva, Cintia S.

2016-01-01

Purpose To evaluate the efficacy of a controlled release dexamethasone delivery system for suppressing inflammation in an ocular burn + desiccating stress (OB+DS) model. Methods Nanowafers (NW) loaded with Dexamethasone (Dex, 10 μg) or vehicles (2.5% Methylcellulose; MC) were fabricated using hydrogel template strategy. C57BL/6 mice were subjected to unilateral alkali ocular burn with concomitant desiccating stress for 2 or 5 days and topically treated either with 2 μL of 0.1% Dex or vehicle four times per day and compared with mice that had MC-NW or Dex-NW placed on their corneas. Clinical parameters were evaluated daily. Mice were euthanized after 2 or 5 days. Quantitative PCR evaluated the expression of inflammatory cytokines IL-1β and IL-6 and matrix metalloproteinases (MMP) in whole cornea lysates. Myeloperoxidase activity (MPO) was measured using a commercial kit in cornea lysates. Results Both Dex drop and Dex-NW groups had significantly lower corneal opacity scores compared with their vehicles. Both Dex drops and Dex-NW significantly decreased expression of IL-1β, IL-6, and MMP-9 RNA transcripts compared with vehicle drops or wafers 2 and 5 days after the initial lesion. A significant lower number of neutrophils was found in both Dex treatment groups and this was accompanied by decreased MPO activity compared with vehicle controls. Conclusions Dex-NW has efficacy equal to Dex drops in preserving corneal clarity and decreasing expression of MMPs and inflammatory cytokines of the corneas of mice subjected to an OB+DS model. PMID:27327581

Femtosecond laser cutting of human corneas for the subbasal nerve plexus evaluation.

Science.gov (United States)

Kowtharapu, B S; Marfurt, C; Hovakimyan, M; Will, F; Richter, H; Wree, A; Stachs, O; Guthoff, R F

2017-01-01

Assessment of various morphological parameters of the corneal subbasal nerve plexus is a valuable method of documenting the structural and presumably functional integrity of the corneal innervation in health and disease. The aim of this work is to establish a rapid, reliable and reproducible method for visualization of the human corneal SBP using femtosecond laser cut corneal tissue sections. Trephined healthy corneal buttons were fixed and processed using TissueSurgeon-a femtosecond laser based microtome, to obtain thick tissue sections of the corneal epithelium and anterior stroma cut parallel to the ocular surface within approximately 15 min. A near infrared femtosecond laser was focused on to the cornea approximately 70-90 μm from the anterior surface to induce material separation using TissueSurgeon. The obtained corneal sections were stained following standard immunohistochemical procedures with anti-neuronal β-III tubulin antibody for visualization of the corneal nerves. Sections that contained the epithelium and approximately 20-30 μm of anterior stroma yielded excellent visualisation of the SBP with minimal optical interference from underlying stromal nerves. In conclusion, the results of this study have demonstrated that femtosecond laser cutting of the human cornea offers greater speed, ease and reliability than standard tissue preparation methods for obtaining high quality thick sections of the anterior cornea cut parallel to the ocular surface. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Specific demographic factors could predict deceased potential cornea donors: A retrospective study from Beijing Tongren Hospital Eye Bank.

Science.gov (United States)

Liu, Yang; Zhang, Yingnan; Zhang, Jing; Yu, Jin; Liang, Qingfeng; Pan, Zhiqiang

2017-12-01

Compared with evident cornea donors (ECDs), deceased potential cornea donors (DPCDs) have no obvious donor identifications to reference, which causes many eligible cornea tissues to be wasted. The demographic characteristics of DPCDs might be different from those of ECDs owing to the following different features: donation consent provided by relatives and willingness to donate before death. Thus, the aim of this study is to reveal the demographic characteristics of DPCDs by comparing DPCDs and ECDs.The demographic factors of 138 donors (both DPCDs and ECDs) were collected from the Beijing Tongren Hospital Eye Bank database and analyzed. To differentiate DPCDs from ECDs using the above-mentioned features, we interviewed the relatives of the donors by telephone. The relatives' attitudes toward cornea donation and their suggestions for our donation service were also acquired during the interview. Two logistic regressions were performed to reveal the demographic factors influencing the 2 features and indicate DPCDs.The donors had certain demographic characteristics (elderly, secondary, or tertiary education level, central district resident), and the most frequent cause of death for the donors was a malignant tumor (n = 56, 43.1%). All the relatives had positive attitudes toward cornea donations, and they hoped to increase publicity efforts to encourage more people to donate and establish more convenient and efficient access for cornea donation. In univariate regressions, age (P = .004, >50 years: odds ratio [OR] = 6.89, 95% confidence interval [CI]: 1.82-26.05), marital status (P = .043, divorced: OR = 9.00,95% CI: 1.33-60.80) significantly influenced relative consent, whereas age (P = .001, >50 years: OR = 15.00, 95% CI: 3.00-74.98), and family address (P = .001, central district: OR = 1) were significant factors influencing the willingness to donate before death. In multivariate regression, age (P = .021, >50 years: OR = 8

Infrared irradiation alters the expression of matrix metalloproteinases and glycosaminoglycans in the cornea and crystalline lens.

Science.gov (United States)

Dadoukis, Panagiotis; Klagas, Ioannis; Komnenou, Anastasia; Karakiulakis, George; Karoutis, Athanasios; Karampatakis, Vassilios; Papakonstantinou, Eleni

2013-08-01

Prolonged exposure to infrared (IR) radiation is associated with different types of damage to cornea and lens. The aim of our study was to investigate the effect of acute and chronic exposure to IR radiation on the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9 and on the expression of glycosaminoglycans (GAG) in the rabbit cornea and crystalline lens. New Zealand rabbits were subjected to IR radiation for 4 months (chronic exposure to IR) or to normal light (control group). In experiments regarding acute exposure, animals were subjected to IR radiation or normal light for 12 h, in the presence of 0.1% diclofenac sodium (eye drops instilled in the right eye of animals) or saline (instilled in the left eye of animals). The cornea and lens were dissected away and homogenized. The activity of MMP-2 and MMP-9 was assayed by gelatine zymography. Total GAG were isolated from tissue specimens after lipid extraction and extensive digestion with pronase and DNase and characterized by treatment with GAG-degrading enzymes, followed by electrophoresis on cellulose acetate membranes. Acute or chronic exposure to IR radiation induced the activity of MMP-2 in cornea and lens, whereas only acute IR radiation increased the content of heparan sulphate in crystalline lens. Local administration of diclofenac sodium did not prevent the above effects of acute IR radiation. The detrimental effects of excessive or prolonged exposure of the eyes to IR radiation are associated with induced activity of MMP-2 in cornea and lens and alterations in the content of heparan sulphate in lens. Thus, MMP and GAG may offer alternative targets for pharmacological intervention to confront ocular damages associated with IR radiation.

[Biological availability of ophthalmic drugs. 1. Increasing drug permeability in the cornea].

Science.gov (United States)

Masteiková, R; Chalupová, Z; Savickiene, N

2004-03-01

Most eye diseases are treated by topical administration of ophthalmic preparations. Low ophthalmic bioavailability is due to a number of physiological and physicochemical factors. The main obstacle to the penetration of active ingredients to the eye is the layered character of the cornea. Formulation of ophthalmic preparations enabling easier penetration of this biological barrier thus ranks among the most effective ways of improving bioavailability. Penetrability of the cornea can be increased by the following methods: a) adjustment of the actual acidity in such a way that pH of the preparation makes it possible to produce the optimal portion of non-ionized particles; b) incorporation of absorption enhancers (non-ionic tensides, salts of bile acids, some antimicrobial substances, EDTA, cyclodextrins, etc.) into the composition of the preparation, and c) production of prodrugs or ionic pairs.

Corneal Collagen Cross-Linking with Hypoosmolar Riboflavin Solution in Keratoconic Corneas

Directory of Open Access Journals (Sweden)

Shaofeng Gu

2014-01-01

Full Text Available Purpose. To report the 12-month outcomes of corneal collagen cross-linking (CXL with a hypoosmolar riboflavin and ultraviolet-A (UVA irradiation in thin corneas. Methods. Eight eyes underwent CXL using a hypoosmolar riboflavin solution after epithelial removal. The corrected distance visual acuity (CDVA, manifest refraction, the mean thinnest corneal thickness (MTCT, and the endothelial cell density (ECD were evaluated before and 6 and 12 months after CXL. Results. The MTCT was 413.9 ± 12.4 μm before treatment and reduced to 381.1 ± 7.3 μm after the removal of the epithelium. After CXL, the thickness decreased to 410.3 ± 14.5 μm at the last follow-up. Before treatment, the mean K-value of the apex of the keratoconus corneas was 58.7 ± 3.5 diopters and slightly decreased (57.7 ± 4.9 diopters at 12 months. The mean CDVA was 0.54 ± 0.23 logarithm of the minimal angle of resolution before treatment and increased to 0.51 ± 0.21 logarithm at the last follow-up. The ECD was 2731.4 ± 191.8 cells/mm2 before treatment and was 2733.4 ± 222.6 cells/mm2 at 12 months after treatment. Conclusions. CXL with a hypoosmolar riboflavin in thin corneas seems to be a promising method for keratoconic eyes with the mean thinnest corneal thickness less than 400 μm without epithelium.

In vivo 3D measurement of moxifloxacin and gatifloxacin distributions in the mouse cornea using multiphoton microscopy

OpenAIRE

Lee, Seunghun; Lee, Jun Ho; Park, Jin Hyoung; Yoon, Yeoreum; Chung, Wan Kyun; Tchah, Hungwon; Kim, Myoung Joon; Kim, Ki Hean

2016-01-01

Moxifloxacin and gatifloxacin are fourth-generation fluoroquinolone antibiotics used in the clinic to prevent or treat ocular infections. Their pharmacokinetics in the cornea is usually measured from extracted ocular fluids or tissues, and in vivo direct measurement is difficult. In this study multiphoton microscopy (MPM), which is a 3D optical microscopic technique based on multiphoton fluorescence, was applied to the measurement of moxifloxacin and gatifloxacin distribution in the cornea. I...

In vivo imaging through the entire thickness of human cornea by full-field optical coherence tomography

Science.gov (United States)

Mazlin, Viacheslav; Xiao, Peng; Dalimier, Eugénie; Grieve, Kate; Irsch, Kristina; Sahel, José; Fink, Mathias; Boccara, Claude

2018-02-01

Despite obvious improvements in visualization of the in vivo cornea through the faster imaging speeds and higher axial resolutions, cellular imaging stays unresolvable task for OCT, as en face viewing with a high lateral resolution is required. The latter is possible with FFOCT, a method that relies on a camera, moderate numerical aperture (NA) objectives and an incoherent light source to provide en face images with a micrometer-level resolution. Recently, we for the first time demonstrated the ability of FFOCT to capture images from the in vivo human cornea1. In the current paper we present an extensive study of appearance of healthy in vivo human corneas under FFOCT examination. En face corneal images with a micrometer-level resolution were obtained from the three healthy subjects. For each subject it was possible to acquire images through the entire corneal depth and visualize the epithelium structures, Bowman's layer, sub-basal nerve plexus (SNP) fibers, anterior, middle and posterior stroma, endothelial cells with nuclei. Dimensions and densities of the structures visible with FFOCT, are in agreement with those seen by other cornea imaging methods. Cellular-level details in the images obtained together with the relatively large field-of-view (FOV) and contactless way of imaging make this device a promising candidate for becoming a new tool in ophthalmological diagnostics.

A human hemi-cornea model for eye irritation testing: quality control of production, reliability and predictive capacity.

Science.gov (United States)

Engelke, M; Zorn-Kruppa, M; Gabel, D; Reisinger, K; Rusche, B; Mewes, K R

2013-02-01

We have developed a 3-dimensional human hemi-cornea which comprises an immortalized epithelial cell line and keratocytes embedded in a collagen stroma. In the present study, we have used MTT reduction of the whole tissue to clarify whether the production of this complex 3-D-model is transferable into other laboratories and whether these tissues can be constructed reproducibly. Our results demonstrate the reproducible production of the hemi-cornea model according to standard operation procedures using 15 independent batches of reconstructed hemi-cornea models in two independent laboratories each. Furthermore, the hemi-cornea tissues have been treated with 20 chemicals of different eye-irritating potential under blind conditions to assess the performance and limitations of our test system comparing three different prediction models. The most suitable prediction model revealed an overall in vitro-in vivo concordance of 80% and 70% in the participating laboratories, respectively, and an inter-laboratory concordance of 80%. Sensitivity of the test was 77% and specificity was between 57% and 86% to discriminate classified from non-classified chemicals. We conclude that additional physiologically relevant endpoints in both epithelium and stroma have to be developed for the reliable prediction of all GHS classes of eye irritation in one stand alone test system. Copyright © 2012 Elsevier Ltd. All rights reserved.

Clear corneal incision leakage after phacoemulsification--detection using povidone iodine 5%.

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Chee, Soon-Phaik

2005-01-01

The purpose of this work was to study the incidence of clear corneal wound leakage at the conclusion of standard co-axial phacoemulsification in a prospective observational series of 100 consecutive cataract cases in a single surgeon's institutional practice. At the conclusion of standard co-axial phacoemulsification using a 2.75 mm temporal single plane clear corneal incision with a 1 mm clear corneal side-port incision, the wounds were hydrated and checked for water-tightness. Povidone iodine 5% (P-I) was then evenly dripped over the cornea and the wounds were inspected visually. Any leakage of aqueous observed was recorded. The amount of leakage was graded as small or large from each wound. Leaky wounds were further hydrated and retested with P-I until sealed. Wound integrity was reassessed on the first postoperative day by use of fluorescein. Of the 100 cases, wound leakage was observed for 31 eyes (31%)-ten main incisions, nineteen side-port incisions, and both incisions in two cases. Wound leakage was easily detected as a ribbon of clear fluid streaming from the incision amid a pool of brown solution. Povidone iodine was not observed within the tract in any incision. All wound leakage was small except for one from the main incision and two from the side-port incision. None of the eyes developed wound leakage the day after surgery and none developed endophthalmitis. In conclusion, leakage from clear corneal incisions at the conclusion of phacoemulsification occurs in almost a third of cases, predominantly from the side incision. It is easily detected by use of the P-I test.

Donor cornea procurement: six-year review of the role of the eye bank in South Australia.

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Williams, K A; White, M A; Badenoch, P R; Wedding, T R; Alfrich, S J; Sawyer, M A; Noack, L M; Johnstone, E W; Zilm, G; Coster, D J

1990-02-01

The Lions Eye Bank of South Australia was established six years ago and has collected corneas from 790 donors. The consent rate is currently 82% of requests made. Two-thirds of donors have been male, with mean donor age/year varying from 54 to 64 years (range two to 93 years). Cardiovascular and respiratory diseases, trauma and haemorrhage account for 80% of all donor deaths. Mean death to enucleation time is five hours. Corneas assessed as being of excellent or very good quality are released preferentially from the bank; those with central endothelial cell counts of less than 1500 cells/mm2 are discarded. Fewer than 1% of donors have returned a positive result for HIV or hepatitis B. Of the 1580 corneas collected by the bank, 863 (55%) have been used for transplantation with a primary non-function rate of 0.46%. The evolving policies, logistics of operation and methodologies employed by the bank are described in detail.

Estudo comparativo entre duas plataformas para realização de Lasik personalizado para correção de miopia e astigmatismo: Alcon CustomCornea® versus Bausch & Lomb Zyoptix® Wavefront-Guided Lasik for low to moderate myopia: CustomCornea® versus Zyoptix®

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Telma Pereira Barreiro

2009-08-01

Full Text Available OBJETIVO: Comparar os resultados obtidos após o Lasik personalizado utilizando duas plataformas diferentes. MÉTODOS: Estudo prospectivo, randomizado com 50 pacientes míopes submetidos a cirurgia refrativa em ambos os olhos. Foram selecionados para o estudo, pacientes com equivalente esférico semelhante entre os olhos. Todos foram submetidos a Lasik bilateral e simultâneo, sendo que um olho foi operado pela plataforma CustomCornea® e o outro pela Zyoptix®. Acuidade visual sem e com correção, refração dinâmica e estática, medida das aberrações oculares, teste de sensibilidade ao contraste foram realizados no período pré-operatório e pós-operatório de 1, 3 e 6 meses. RESULTADOS: No período pré-operatório a média do equivalente esférico era de -3,29 ± 1,56 D no grupo CustomCornea® e de -3,22 ± 1,50 D no Zyoptix® (p=0,267. No sexto mês de pós-operatório, a média do equivalente esférico no grupo CustomCornea® era de -0,077 ± 0,23 D e -0,282 ± 0,30 D no Zyoptix® (p 20/20 foi alcançada em 86% dos olhos no grupo CustomCornea® e 70% no grupo Zyoptix® (p=0,094. Nenhum paciente perdeu duas ou mais linhas da melhor acuidade visual corrigida. Cem por cento dos olhos CustomCornea® e 88% dos Zyoptix® ficaram entre ± 0,50 D da emetropia (p=0,014*. Melhora da sensibilidade ao contraste em todas as frequências espaciais testadas foi observada em ambos os grupos. A aberração esférica apresentou aumento em ambos os grupos, porém este foi estatisticamente maior na plataforma Zyoptix® (pPURPOSE: To compare the visual and clinical outcomes of Wavefront-guided laser in situ keratomileusis (Lasik with Alcon CustomCornea® and Zyoptix® systems. METHODS: A prospective, randomized, masked and bilateral study was conducted. Fifty patients with preoperative spherical equivalent ranging from -1.00 to -6.50 D were enrolled for customized ablation in both eyes. All of them were submitted to Lasik CustomCornea® treatment in one

Adjunctive cryotherapy for pigmentary keratitis in dogs: a study of 16 corneas.

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Azoulay, Thierry

2014-07-01

To assess whether soft cryotherapy (dimethylether, isobutene, and propane) can remove pigmentation of the cornea that has accumulated under different conditions when conventional therapy has been unsuccessful. Nine dogs with unilateral or bilateral corneal pigmentation (16 eyes) were included based on progressive corneal pigmentation that was unresponsive to long-term etiological treatment. The dogs had keratoconjunctivitis sicca or chronic superficial keratitis. A cryogen of 95% dimethylether, 3% isobutane, and 2% propane was applied to the pigmented areas of each cornea under anesthesia. Initial corneal pigmentation and changes were documented over the entire study period using a grading scheme and clinical photographs. Most of the pigment deposits were gone by 5-15 days after cryosurgery. Postoperatively, the dogs showed some corneal edema and corneo-conjunctival inflammation, and three dogs had superficial corneal ulcers; these symptoms had resolved by 1 month after the procedure. Follow-up for more than 90 days was available in five dogs (nine corneas), and we observed total or partial repigmentation when the underlying disease was not controlled. A new cryotherapy procedure was successfully performed in two of these dogs. Given the sensitivity to cold of melanocytes, cryotherapy is a viable adjunctive treatment for refractory severe corneal pigmentation. Etiological treatment remains necessary to prevent pigmentation from rapidly reappearing. Only a few dogs were followed for more than 90 days; further study is necessary to evaluate the long-term safety and efficacy of soft cryotherapy. © 2013 American College of Veterinary Ophthalmologists.

Finite element analysis of blunt foreign body impact on the cornea after PRK and LASIK.

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Mousavi, Seyed Jamaleddin; Nassiri, Nariman; Masoumi, Nafiseh; Nassiri, Nader; Majdi-N, Mercede; Farzaneh, Solmaz; Djalilian, Ali R; Peyman, Gholam A

2012-01-01

To investigate the effect of blunt foreign body impact on a human cornea after photorefractive keratectomy (PRK) and LASIK using a simulation model. Computational simulations were performed using a finite element analysis program (LS-Dyna, Livermore Software Technology Corp). The blunt foreign body was set to impact at the center of the corneal surface models (after PRK and LASIK) with thicknesses of 500, 450, 400, 350, and 300 μm. Corneal rupture was assumed to occur at a peak stress of 9.45 MPa and at a strain of 18%. The foreign body projectile was blunt in shape, made from aluminum, contained plastic-kinematic properties, and had a density of 2700 kg/m(3). The projectile was launched at the center of the cornea with velocities ranging from 20 to 60 m/s. The threshold of impact velocities creating rupture in corneal thicknesses of 500, 450, 400, 350, and 300 μm were 33, 32.8, 30.7, 27.9, and 22.8 m/s, respectively, in the PRK model. In the LASIK model, the thresholds creating rupture in the stromal bed of the corneas with thicknesses of 500, 450, 400, 350, and 300 μm were 40, 38.1, 35.6, 31.5, and 26.7 m/s, respectively. The 110-μm corneal flap in the LASIK model ruptured at all velocities. Ruptures occurred at lower velocities in the PRK cornea model than in the corneal stromal bed of the LASIK model following blunt foreign body impact. Copyright 2012, SLACK Incorporated.

Adaptive digital filters

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Kovačević, Branko; Milosavljević, Milan

2013-01-01

“Adaptive Digital Filters” presents an important discipline applied to the domain of speech processing. The book first makes the reader acquainted with the basic terms of filtering and adaptive filtering, before introducing the field of advanced modern algorithms, some of which are contributed by the authors themselves. Working in the field of adaptive signal processing requires the use of complex mathematical tools. The book offers a detailed presentation of the mathematical models that is clear and consistent, an approach that allows everyone with a college level of mathematics knowledge to successfully follow the mathematical derivations and descriptions of algorithms.   The algorithms are presented in flow charts, which facilitates their practical implementation. The book presents many experimental results and treats the aspects of practical application of adaptive filtering in real systems, making it a valuable resource for both undergraduate and graduate students, and for all others interested in m...

Determination of natamycin in rabbit cornea by high-performance liquid chromatography-tandem mass spectrometry with protective soaking extraction technology.

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Tianyang, Zhou; Ling, Zhu; Huiyun, Xia; Jijun, He; Junjie, Zhang

2014-10-15

A new selective and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantification of natamycin (NAT) in rabbit corneas with amphotericin B as the internal standard (IS). The cornea samples were processed by a simple and protective methanol soaking extraction technology. The NAT could be extracted completely from rabbit cornea after 24h of soaking with methanol under a mild condition. Chromatographic separation was performed on a C18 column (2.1mm×50mm, 3.5μm) using mobile phase with ammonium acetate buffer (pH 4.5; 4.0mM):acetonitrile (40:60, v/v) at a flow rate of 0.25ml/min. Quantification was performed using the transitions 666.2→503.2 m/z for NAT and 924.5→906.6 m/z for IS by positive ion electrospray ionization in multiple reaction monitoring mode. The assay was validated over a concentration range of 8.64ng/ml to 843ng/ml with lower limit of detection of 4.32ng/ml. The method was validated with respect to linearity, accuracy, precision, recovery, stability and extracting efficiency. The extraction recovery of NAT from cornea samples was approximately 100% with the new methanol soaking extraction procedure. The method has been successfully applied to the ocular pharmacokinetic studies of NAT eye drops in the cornea of Japanese white rabbit. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of the eye irritation potential of chemicals: A comparison study between two test methods based on human 3D hemi-cornea models.

Science.gov (United States)

Tandon, R; Bartok, M; Zorn-Kruppa, M; Brandner, J M; Gabel, D; Engelke, M

2015-12-25

We have recently developed two hemi-cornea models (Bartok et al., Toxicol in Vitro 29, 72, 2015; Zorn-Kruppa et al. PLoS One 9, e114181, 2014), which allow the correct prediction of eye irritation potential of chemicals according to the United Nations globally harmonized system of classification and labeling of chemicals (UN GHS). Both models comprise a multilayered epithelium and a stroma with embedded keratocytes in a collagenous matrix. These two models were compared, using a set of fourteen test chemicals. Their effects after 10 and 60 minutes (min) exposure were assessed from the quantification of cell viability using the MTT reduction assay. The first approach separately quantifies the damage inflicted to the epithelium and the stroma. The second approach quantifies the depth of injury by recording cell death as a function of depth. The classification obtained by the two models was compared to the Draize rabbit eye test and an ex vivo model using rabbit cornea (Jester et al. Toxicol in Vitro. 24, 597-604, 2010). With a 60 min exposure, both of our models are able to clearly differentiate UN GHS Category 1 and UN GHS Category 2 test chemicals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurement and modeling of diffusion kinetics of a lipophilic molecule across rabbit cornea.

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Gupta, Chhavi; Chauhan, Anuj; Mutharasan, Raj; Srinivas, Sangly P

2010-04-01

To develop a kinetic model for representing the diffusion and partitioning of Rhodamine B (RhB), a fluorescent lipophilic molecule, across the cornea for gaining insights into pharmacokinetics of topical drugs to the eye. Rabbit corneas mounted underneath a custom-built scanning microfluorometer were perfused with Ringers on both sides of the tissue. After a step change in RhB on the tear side, transients of trans-corneal fluorescence of RhB were measured at a depth resolution approximately 8 microm. RhB distribution exhibited discontinuities at the interface between epithelium and stroma, and between stroma and endothelium. In each of the layers, fluorescence was non-uniform. Fluorescence was elevated in the epithelium and endothelium relative to the stroma. Modeling of RhB transport by diffusion in each layer and stipulation of partitioning of RhB at the cellular interfaces were required to account for trans-corneal penetration kinetics of RhB. The model parameters, estimated using the unsteady state trans-corneal RhB profiles, were found to be sensitive, and the model predicted the experimental profiles accurately. Conventional pharmacokinetic models that depict cornea as a single compartment do not predict the depth-dependent kinetics of RhB penetration. The proposed model incorporates realistic transport mechanisms and thereby highlights the influence of physicochemical properties of drugs on trans-corneal kinetics.

Influence of the He-Ne laser in different irradiation regimes on the cornea cells after ionizing irradiation

International Nuclear Information System (INIS)

Bulyakova, N.V.

1984-01-01

A study was made on epithelium cells of the eye cornea in mices entering the first postradiation mitosis. The influence of laser rays acting in the course of each exposure during one and the same period of time, or continuously, or by pulses was compared. The effect of laser radiation was evaluated from the frequency of occurrence of cells with chromosomal aberrations, mitotic index, coefficient of mitosis phases. It has been established that pulse radiation of a helium-neon laser in a certain operation regime produces a sanitating effect on cells of eye cornea epithelium in white mice damaged by ionizing radiation. Cells being killed in the interphase were not revealed in epithelium of the eye cornea. It enables to conclude that the amount of aberrant mitoses decreases as a result of postradiation repair of cells damaged by ionizing radiation, but not as a result of their elimination

A short-term study of corneal collagen cross-linking with hypo-osmolar riboflavin solution in keratoconic corneas

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Shao-Feng Gu

2015-02-01

Full Text Available AIM: To report the 3mo outcomes of collagen cross-linking (CXL with a hypo-osmolar riboflavin in thin corneas with the thinnest thickness less than 400 μm without epithelium. METHODS: Eight eyes in 6 patients with age 26.2±4.8y were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution after its de-epithelization. Best corrected visual acuity, manifest refraction, the thinnest corneal thickness, and endothelial cell density were evaluated before and 3mo after the procedure. RESULTS: The mean thinnest thickness of the cornea was 408.5±29.0 μm before treatment and reduced to 369.8±24.8 μm after the removal of epithelium. With the application of the hypo-osmolar riboflavin solution, the thickness increased to 445.0±26.5 μm before CXL and recover to 412.5±22.7 μm at 3mo after treatment, P=0.659. Before surgery, the mean K-value of the apex of the keratoconus corneas was 57.6±4.0 diopters, and slightly decreased (54.7±4.9 diopters after surgery (P=0.085. Mean best-corrected visual acuity was 0.55±0.23 logarithm of the minimal angle of resolution, and increased to 0.53±0.26 logarithm after surgery (P=0.879. The endothelial cell density was 2706.4±201.6 cells/mm2 before treatment, and slightly decreased (2641.2±218.2 cells/mm2 at last fellow up (P=0.002. CONCLUSION: Corneal collagen cross-linking with a hypo-osmolar riboflavin in thin corneas seems to be a promising treatment. Further study should be done to evaluate the safety and efficiency of CXL in thin corneas for the long-term.

Total laparoscopic retrieval of inferior vena cava filter.

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Benrashid, Ehsan; Adkar, Shaunak Sanjay; Bennett, Kyla Megan; Zani, Sabino; Cox, Mitchell Wayne

2015-01-01

While there is some local variability in the use of inferior vena cava filters and there has been some evolution in the indications for filter placement over time, inferior vena cava filters remain a standard option for pulmonary embolism prophylaxis. Indications are clear in certain subpopulations of patients, particularly those with deep venous thrombosis and absolute contraindications to anticoagulation. There are, however, a variety of reported inferior vena cava filter complications in the short and long term, making retrieval of the filter desirable in most cases. Here, we present the case of a morbidly obese patient complaining of chronic abdominal pain after inferior vena cava filter placement and malposition of the filter with extensive protrusion outside the inferior vena cava. She underwent successful laparoscopic retrieval of her malpositioned inferior vena cava filters after failure of a conventional endovascular approach.

Total laparoscopic retrieval of inferior vena cava filter

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Ehsan Benrashid

2015-08-01

Full Text Available While there is some local variability in the use of inferior vena cava filters and there has been some evolution in the indications for filter placement over time, inferior vena cava filters remain a standard option for pulmonary embolism prophylaxis. Indications are clear in certain subpopulations of patients, particularly those with deep venous thrombosis and absolute contraindications to anticoagulation. There are, however, a variety of reported inferior vena cava filter complications in the short and long term, making retrieval of the filter desirable in most cases. Here, we present the case of a morbidly obese patient complaining of chronic abdominal pain after inferior vena cava filter placement and malposition of the filter with extensive protrusion outside the inferior vena cava. She underwent successful laparoscopic retrieval of her malpositioned inferior vena cava filters after failure of a conventional endovascular approach.

Comparison of Scheimpflug imaging parameters between steep and keratoconic corneas of Caucasian eyes

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Huseynova T

2016-04-01

Full Text Available Tukezban Huseynova,1 Farah Abdulaliyeva,2 Michele Lanza3 1Briz-L Eye Clinic, 2National Ophthalmology Center, Baku, Azerbaijan; 3Second University of Naples, Caserta, Campania, Italy Purpose: To compare the keratometric and pachymetric parameters of healthy eyes with those affected by steep cornea and keratoconus (KC using Scheimpflug camera.Setting: Briz-L Eye Clinic, Baku, Azerbaijan.Design: A cross-sectional study.Methods: In this study, 49 KC (Amsler–Krumeich stage 1 eyes and 36 healthy eyes were enrolled. A complete ophthalmic evaluation and a Scheimpflug camera scan were performed in every eye included in the study. Tomographic parameters such as parameters from the front and back cornea, maximum keratometry reading (Kmax, corneal volume (CV, anterior chamber volume (ChV, anterior chamber depth (ACD, anterior chamber angle (AC angle, keratometric power deviation (KPD, maximum front elevation (Max FE, and maximum back elevation (Max BE, as well as pachymetric progression indices (PPI, Ambrosio relational thickness (ART, index of surface variance (ISV, index of vertical asymmetry (IVA, center keratoconus index (CKI, index of height asymmetry (IHA, index of height decentration (IHD, and radius minimum (RM were collected and statistically compared between the two groups.Results: PPI, ART, ISV, IVA, CKI, IHA, IHD, and RM parameter values were significantly different (P<0.05 between the KC and healthy eyes. There were no significant differences in K mean and Q values of the frontal corneal parameters, as well as in Kmax, AC angle, RM, back, and front astigmatism, between stage 1 keratoconic and normal Caucasian eyes with steep cornea. All other parameters such as K mean and Q values of the back corneal parameters, Max FE, Max BE, ACD, ChV, and CV showed significant differences between the groups (P<0.05 for all. Conclusion: Scheimpflug imaging is able to detect corneal morphological differences between stage 1 KC eyes and healthy eyes with

Preparation of pre-cut corneas from fresh donated whole globes for Descemet's stripping automated keratoplasty: 3-year results at the Central Eye Bank of Iran.

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Kanavi, Mozhgan Rezaei; Javadi, Mohammad Ali; Javadi, Fatemeh; Chamani, Tahereh

2014-09-01

To describe the technique and the results of the preparation of pre-cut corneas for Descemet's stripping automated endothelial keratoplasty (DSAEK) during a 3-year period at the Central Eye Bank of Iran (CEBI). The method of preparation of pre-cut corneas from donated whole globes at the CEBI is described and the frequency and percentage of pre-cut corneas prepared for DSAEK, between April 2009 and March 2012, are specified. Moreover, post-operative reports are reviewed for any complaints about using pre-cut tissues for DSAEK. Out of the 1,518 donated whole globes appropriate for DSAEK, 1,478 (97.4 %) pre-cut corneas were successfully prepared. The method of preparation failed in 40 (2.6 %) cases. Based on the eye bank post-operative reports, thickness of pre-cut tissues for DSAEK was deemed unacceptable in only 6 (0.4 %) cases prior to surgery; five of these were too thick and one was too thin. Preparation of pre-cut corneas, for DSAEK from donated whole globes, in the CEBI is a safe and easy method, with very good preservation of endothelial cells after the preparation of the pre-cut corneas and reduced risks from corneal manipulation.

Visual acuity outcomes in eyes with flat corneas after PRK.

Science.gov (United States)

Varssano, David; Waisbourd, Michael; Minkev, Liza; Sela, Tzahi; Neudorfer, Meira; Binder, Perry S

2013-06-01

To evaluate the impact of corneal curvatures less than 35 diopters (D) after photorefractive keratectomy (PRK) on visual acuity outcomes. Visual acuity outcomes of 5,410 eyes that underwent PRK from January 2006 to November 2010 were retrospectively analyzed for the impact of postoperative corneal curvatures on visual outcomes. All procedures were performed on a single platform (Allegretto 200Hz excimer laser; Alcon Laboratories, Inc., Irvine, CA). Main outcome measures were postoperative corrected distance visual acuity (CDVA) and loss of CDVA. Corneas with a measured or a calculated postoperative flat meridian less than 35 D and those with a measured postoperative steep meridian less than 35 D had worse postoperative CDVA than corneas with meridians of either 35 D or more (P ≤ .021). However, the preoperative CDVA was worse in the flatter curvatures in all comparisons performed (P ≤ .024). Consequently, the measured or calculated meridian curvature had no effect on CDVA loss (P ≥ .074). Postoperative corneal keratometry values (flat and steep meridians) less than 35 D did not have a predictive effect on the risk of losing visual acuity following myopic PRK performed on the Allegretto 200Hz excimer laser. Copyright 2013, SLACK Incorporated.

Effect of In Vitro Transcorneal Approach of Aceclofenac Eye Drops through Excised Goat, Sheep, and Buffalo Corneas

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Vivek Dave

2015-01-01

Full Text Available The current study involves the evaluation of factors that influence the transcorneal permeation of aqueous drops of aceclofenac ophthalmic formulation through freshly excised goat, sheep, and buffalo corneas. Aceclofenac formulation with different concentrations 0.1–0.5% (w/v and with different pH and different preservatives, was taken into account. The amount of drug permeated from different formulations was estimated using an Franz diffusion cell. A linear increase in drug permeation was observed with increase in pH (5.5 to 7.4. The apparent permeability coefficient was found to be maximum 15.01±0.45 on goat cornea and maximum transport of aceclofenac was observed at physiological pH of tears (i.e., 7. The results advocate that aceclofenac 0.5% (w/v ophthalmic solution (pH 7.0 containing BAK (0.01% provides maximum in vitro ocular permeability through goat, sheep, and buffalo corneas.

Removal of a barbed fish hook from the cornea of an 8-year-old boy.

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Kemp, Pavlina S; Shah, Ankoor S; Elliott, Alexandra T; Wan, Michael J

2017-10-01

This video article shows the surgical removal of a three-pronged barbed fish hook from the cornea and anterior chamber of an 8-year-old boy. The advance-and-cut method is shown: the embedded barbed point of the fish hook was advanced through the cornea, its point was cut off, and the shank of the hook was withdrawn. This method was chosen due to the three-pronged configuration of the fish hook to minimize additional trauma to the eye. Other methods of fish hook removal are briefly reviewed. Copyright © 2017 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

The ultrastructural alterations in rat corneas with experimentally-induced diabetes mellitus

International Nuclear Information System (INIS)

Take, G.; Karabay, G.; Erdogan, D.; Duyar, I.

2006-01-01

To examine the ultrastructural changes of rat corneas in streptozotocin (STZ) induced diabetes mellitus and the and the follow-up insulin treatment. Sprague-Dawley type rats were used for experimental procedures during the period from January to April 2003 at Baskent University, Ankara, Turkey. Rats were studied in four groups: group 1: controls, group 2 sham controls (single dose IV sodium citrate); group 3 STZ-induced diabetes mellitus (Single dose 45mg/kg STZ intravenously), group 4: diabetes mellitus + insulin treatment (8U/day). We observed degenerative changes in the epithelial layer, stromal keratocytes and endothelial cells in diabetic group. In contrast, the corneal layers have revealed positive alterations in the insulin-treated group. The statistical analysis, showed significant narrowing in the epithelial layer in the diabetic group (p0.02), whereas thickening was observed in the epithelial basement membrane and Descemet's membrane (p=0.002). It was determined that that diabetes mellitus causes degenerative changes in cornea, which are positively influenced by short-term insulin treatment. (author)

[Evaluation of Iris Morphology Viewed through Stromal Edematous Corneas by Infrared Camera].

Science.gov (United States)

Kobayashi, Masaaki; Morishige, Naoyuki; Morita, Yukiko; Yamada, Naoyuki; Kobayashi, Motomi; Sonoda, Koh-Hei

2016-02-01

We reported that the application of infrared camera enables us to observe iris morphology in Peters' anomaly through edematous corneas. To observe the iris morphology in bullous keratopathy or failure grafts with an infrared camera. Eleven bullous keratopathy or failure grafts subjects (6 men and 5 women, mean age ± SD; 72.7 ± 13.0 years old) were enrolled in this study. The iris morphology was observed by applying visible light mode and near infrared light mode of infrared camera (MeibomPen). The detectability of pupil shapes, iris patterns and presence of iridectomy was evaluated. Infrared mode observation enabled us to detect the pupil shapes in 11 out of 11 cases, iris patterns in 3 out of 11 cases, and presence of iridetomy in 9 out of 11 cases although visible light mode observation could not detect any iris morphological changes. Applying infrared optics was valuable for observation of the iris morphology through stromal edematous corneas.

Biocompatibility of a fish scale-derived artificial cornea: Cytotoxicity, cellular adhesion and phenotype, and in vivo immunogenicity.

Science.gov (United States)

van Essen, T H; van Zijl, L; Possemiers, T; Mulder, A A; Zwart, S J; Chou, C-H; Lin, C C; Lai, H J; Luyten, G P M; Tassignon, M J; Zakaria, N; El Ghalbzouri, A; Jager, M J

2016-03-01

To determine whether a fish scale-derived collagen matrix (FSCM) meets the basic criteria to serve as an artificial cornea, as determined with in vitro and in vivo tests. Primary corneal epithelial and stromal cells were obtained from human donor corneas and used to examine the (in)direct cytotoxicity effects of the scaffold. Cytotoxicity was assessed by an MTT assay, while cellular proliferation, corneal cell phenotype and adhesion markers were assessed using an EdU-assay and immunofluorescence. For in vivo-testing, FSCMs were implanted subcutaneously in rats. Ologen(®) Collagen Matrices were used as controls. A second implant was implanted as an immunological challenge. The FSCM was implanted in a corneal pocket of seven New Zealand White rabbits, and compared to sham surgery. The FSCM was used as a scaffold to grow corneal epithelial and stromal cells, and displayed no cytotoxicity to these cells. Corneal epithelial cells displayed their normal phenotypical markers (CK3/12 and E-cadherin), as well as cell-matrix adhesion molecules: integrin-α6 and β4, laminin 332, and hemi-desmosomes. Corneal stromal cells similarly expressed adhesion molecules (integrin-α6 and β1). A subcutaneous implant of the FSCM in rats did not induce inflammation or sensitization; the response was comparable to the response against the Ologen(®) Collagen Matrix. Implantation of the FSCM in a corneal stromal pocket in rabbits led to a transparent cornea, healthy epithelium, and, on histology, hardly any infiltrating immune cells. The FSCM allows excellent cell growth, is not immunogenic and is well-tolerated in the cornea, and thus meets the basic criteria to serve as a scaffold to reconstitute the cornea. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of the Viscoelastic Properties of the Human Cornea Using Scheimpflug Imaging in Inflation Experiment of Eye Globes

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Lombardo, Giuseppe; Serrao, Sebastiano; Rosati, Marianna; Lombardo, Marco

2014-01-01

Purpose To demonstrate a Scheimpflug-based imaging procedure for investigating the depth- and time-dependent strain response of the human cornea to inflation testing of whole eye globes. Methods Six specimens, three of which with intact corneal epithelium, were mounted in a customized apparatus within a humidity and temperature-monitored wet chamber. Each specimen was subjected to two mechanical tests in order to measure corneal strain resulting from application of cyclic (cyclic regimen) and constant (creep regimen) stress by changing the intra-ocular pressure (IOP) within physiological ranges (18–42 mmHg). Corneal shape changes were analyzed as a function of IOP and both corneal stress-strain curves and creep curves were generated. Results The procedure was highly accurate and repeatable. Upon cyclic stress application, a biomechanical corneal elasticity gradient was found in the front-back direction. The average Young's modulus of the anterior cornea ranged between 2.28±0.87 MPa and 3.30±0.90 MPa in specimens with and without intact epithelium (P = 0.05) respectively. The Young's modulus of the posterior cornea was on average 0.21±0.09 MPa and 0.17±0.06 MPa (P>0.05) respectively. The time-dependent strain response of the cornea to creep testing was quantified by fitting data to a modified Zener model for extracting both the relaxation time and compliance function. Conclusion Cyclic and creep mechanical tests are valuable for investigating the strain response of the intact human cornea within physiological IOP ranges, providing meaningful results that can be translated to clinic. The presence of epithelium influences the results of anterior corneal shape changes when monitoring deformation via Scheimpflug imaging in inflation experiments of whole eye globes. PMID:25397674

Biophysico-functional compatibility of Seoul National University (SNU) miniature pig cornea as xenocorneal graft for the use of human clinical trial.

Science.gov (United States)

Kim, Dong Hyun; Kim, Jaeyoung; Jeong, Hyun Jeong; Lee, Hyun Ju; Kim, Mee Kum; Wee, Won Ryang

2016-05-01

Xenocorneal transplantation is one of the solutions for shortage of donor cornea, and remarkable advances have been made in pig-to-rhesus studies from the immunological perspective. Most successful preclinical trials have been carried out with corneas of the Seoul National University (SNU) miniature pig (SNU pig, genetically unmodified) as donor tissues; however, there has been no biophysico-functional evaluation of the SNU pig cornea as a substitute for human cornea. The purpose of this study was to investigate the biophysical and functional compatibility of SNU pig cornea for use in human clinical trials. Ninety-three eyeballs obtained from 51 SNU pigs were used to evaluate the physical properties and changes in porcine corneal endothelial cells (PCECs) depending on preservation time and storage condition before surgery, proliferative and functional characteristics of PCECs, and the microbiologic safety of porcine cornea. Corneal diameters and curvatures, axial length, anterior chamber depth, and central corneal thickness were measured and compared with previously reported human data. Corneal endothelial cell density (ECD) was serially measured with a confocal microscope during 7 days of preservation in the same storage solution used for human corneas. Corneal endothelial cell proliferation and immunofluorescence staining of Na- and K-dependent ATPase in PCECs were evaluated after 7 days of preservation. The corneoscleral rims of SNU pigs were cultured for gram-positive bacteria, gram-negative bacteria, and fungi to evaluate their microbiological safety. Corneal diameter and thickness in SNU pigs was larger than human and corneal curvature was flatter; however, they were within surgically operable ranges. Mean ECD (day 0) and ECD loss after 7 days of preservation were 2625 ± 81 cells/mm(2) and 7.60 ± 1.53%, respectively, which is comparable to human ECD and ECD loss in the same conditions. The ECD of SNU pigs was inversely decreased with aging (R(2) = 0.4034, P

Alarm filtering and presentation

International Nuclear Information System (INIS)

Bray, M.A.

1989-01-01

This paper discusses alarm filtering and presentation in the control room of nuclear and other process control plants. Alarm generation and presentation is widely recognized as a general process control problem. Alarm systems often fail to provide meaningful alarms to operators. Alarm generation and presentation is an area in which computer aiding is feasible and provides clear benefits. Therefore, researchers have developed several computerized alarm filtering and presentation approaches. This paper discusses problems associated with alarm generation and presentation. Approaches to improving the alarm situation and installation issues of alarm system improvements are discussed. The impact of artificial intelligence (AI) technology on alarm system improvements is assessed. (orig.)

3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea.

Science.gov (United States)

Zhao, Mingtao; Kuo, Anthony N; Izatt, Joseph A

2010-04-26

Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the effects of patient motion during data acquisition. Procedures are described for correction of image data artifacts resulting from 3D refraction of SDOCT light in the cornea and from non-idealities of the scanning system geometry performed as a pre-requisite for accurate parameter extraction. Zernike polynomial 3D reconstruction and a recursive half searching algorithm (RHSA) were implemented to extract clinical keratometric parameters including anterior and posterior radii of curvature, central cornea optical power, central corneal thickness, and thickness maps of the cornea. Accuracy and repeatability of the extracted parameters obtained using a commercial 859nm SDOCT retinal imaging system with a corneal adapter were assessed using a rigid gas permeable (RGP) contact lens as a phantom target. Extraction of these parameters was performed in vivo in 3 patients and compared to commercial Placido topography and Scheimpflug photography systems. The repeatability of SDOCT central corneal power measured in vivo was 0.18 Diopters, and the difference observed between the systems averaged 0.1 Diopters between SDOCT and Scheimpflug photography, and 0.6 Diopters between SDOCT and Placido topography.

The tissue-engineered human cornea as a model to study expression of matrix metalloproteinases during corneal wound healing.

Science.gov (United States)

Couture, Camille; Zaniolo, Karine; Carrier, Patrick; Lake, Jennifer; Patenaude, Julien; Germain, Lucie; Guérin, Sylvain L

2016-02-01

Corneal injuries remain a major cause of consultation in the ophthalmology clinics worldwide. Repair of corneal wounds is a complex mechanism that involves cell death, migration, proliferation, differentiation, and extracellular matrix (ECM) remodeling. In the present study, we used a tissue-engineered, two-layers (epithelium and stroma) human cornea as a biomaterial to study both the cellular and molecular mechanisms of wound healing. Gene profiling on microarrays revealed important alterations in the pattern of genes expressed by tissue-engineered corneas in response to wound healing. Expression of many MMPs-encoding genes was shown by microarray and qPCR analyses to increase in the migrating epithelium of wounded corneas. Many of these enzymes were converted into their enzymatically active form as wound closure proceeded. In addition, expression of MMPs by human corneal epithelial cells (HCECs) was affected both by the stromal fibroblasts and the collagen-enriched ECM they produce. Most of all, results from mass spectrometry analyses provided evidence that a fully stratified epithelium is required for proper synthesis and organization of the ECM on which the epithelial cells adhere. In conclusion, and because of the many characteristics it shares with the native cornea, this human two layers corneal substitute may prove particularly useful to decipher the mechanistic details of corneal wound healing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inter-comparison of different models for estimating clear sky solar global radiation for the Negev region of Israel

International Nuclear Information System (INIS)

Ianetz, Amiran; Lyubansky, Vera; Setter, Ilan; Kriheli, Boris; Evseev, Efim G.; Kudish, Avraham I.

2007-01-01

Solar global radiation is a function of solar altitude, site altitude, albedo, atmospheric transparency and cloudiness, whereas solar global radiation on a clear day is defined such that it is a function of all the abovementioned parameters except cloudiness. Consequently, analysis of the relative magnitudes of solar global radiation and solar global radiation on a clear day provides a platform for studying the influence of cloudiness on solar global radiation. The Iqbal filter for determining the day type has been utilized to calculate the monthly average clear day solar global radiation at three sites in the Negev region of Israel. An inter-comparison between four models for estimating clear sky solar global radiation at the three sites was made. The relative accuracy of the four models was determined by comparing the monthly average daily clear sky solar global radiation to that determined using the Iqbal filter. The analysis was performed on databases consisting of measurements made during the time interval of January 1991 to December 2004. The monthly average daily clear sky solar global radiation determined by the Berlynd model was found to give the best agreement with that determined using the Iqbal filter. The Berlynd model was then utilized to calculate a daily clear day index, K c , which is defined as the ratio of the daily solar global radiation to the daily clear day solar global radiation. It is suggested that this index be used as an indication of the degree of cloudiness. Linear regression analysis was performed on the individual monthly databases for each site to determine the correlation between the daily clear day index and the daily clearness index, K T

Successful treatment of Fusarium keratitis with cornea transplantation and topical and systemic voriconazole.

NARCIS (Netherlands)

Klont, R.R.; Eggink, C.A.; Rijs, A.J.M.M.; Wesseling, P.; Verweij, P.E.

2005-01-01

A case of invasive Fusarium keratitis in a previously healthy male patient was treated successfully with cornea transplantation and systemic and topical voriconazole after treatment failure with topical amphotericin B and systemic itraconazole. Topical voriconazole was well tolerated, and, in

Adaptive Filtering Algorithms and Practical Implementation

CERN Document Server

Diniz, Paulo S R

2013-01-01

In the fourth edition of Adaptive Filtering: Algorithms and Practical Implementation, author Paulo S.R. Diniz presents the basic concepts of adaptive signal processing and adaptive filtering in a concise and straightforward manner. The main classes of adaptive filtering algorithms are presented in a unified framework, using clear notations that facilitate actual implementation. The main algorithms are described in tables, which are detailed enough to allow the reader to verify the covered concepts. Many examples address problems drawn from actual applications. New material to this edition includes: Analytical and simulation examples in Chapters 4, 5, 6 and 10 Appendix E, which summarizes the analysis of set-membership algorithm Updated problems and references Providing a concise background on adaptive filtering, this book covers the family of LMS, affine projection, RLS and data-selective set-membership algorithms as well as nonlinear, sub-band, blind, IIR adaptive filtering, and more. Several problems are...

A Raman scattering and FT-IR spectroscopic study on the effect of the solar radiation in Antarctica on bovine cornea

Science.gov (United States)

Yamamoto, Tatsuyuki; Murakami, Naoki; Yoshikiyo, Keisuke; Takahashi, Tetsuya; Yamamoto, Naoyuki

2010-01-01

The Raman scattering and FT-IR spectra of the corneas, transported to the Syowa station in Antarctica and exposed to the solar radiation of the mid-summer for four weeks, were studied to reveal that type IV collagen involved in corneas were fragmented. The amide I and III Raman bands were observed at 1660 and 1245 cm -1, respectively, and the amide I and II infrared bands were observed at 1655 and 1545 cm -1, respectively, for original corneas before exposure. The background of Raman signals prominently increased and the ratio of amide II infrared band versus amide I decreased by the solar radiation in Antarctica. The control experiment using an artificial UV lamp was also performed in laboratory. The decline rate of the amide II/amide I was utilized for estimating the degree of fragmentation of collagen, to reveal that the addition of vitamin C suppressed the reaction while the addition of sugars promoted it. The effect of the solar radiation in Antarctica on the corneas was estimated as the same as the artificial UV lamp of four weeks (Raman) or one week (FT-IR) exposure.

Enucleaton of the right eye due to large choroidal melanoma with simultaneous penetrating cornea transplantation from OD to OS (Case report.

Directory of Open Access Journals (Sweden)

E. A. Korchuganova

2013-01-01

Full Text Available There is presentation case report of 75‑year old woman with choroidal melanoma (T3N0M0 on the right eye and failed graft on the left pseudophakic eye with far advanced glaucoma and ARMD. No treatment was given to the leading eye with VA 0,2. VA of OS = 1 / ∞ pr.l.certa; PKP OS in 2008 for pseudophakic bullous keratopathy on the eye with far advanced glaucoma. IOP was normal after previous filtering surgery. After PKP VA = 0,04; clear graft during 2 years; then gradually opacification and vascularization occurred. VA dropped to light perception. Echography OD — tumor h 8,29 mm, d 21,77 mm. No ingrowth of tumor into anterior segment of the eye; VA OD = 0 (no light perception. Concerning the need to enucleate the right eye with large choroidal melanoma, the advantage of using corneal autograft from OD to OS, location of tumor in the posterior pole with no ingrowth in anterior segment, the decision was made to perform the following operation — to enucleate the right eye and transplant simultaneously corneal graft from OD on OS. Patient was discharged from the Ophthalmology Hospital with VA OS = 0,01, during next week VA improved to 0,02. 8,0 mm graft isclear, fixed with 8 interruptured and continious suture 10 / 0‑nylon. Anterior chamber — normal depth, atrophic iris, stable position of PC IOL. Optic nerve head is pale with subtotal deep glaucomatous excavation. Conclusion: presented case report demonstrates the rarepossibility to use cornea after enucleation the eye with large malignant tumor (located in the posterior pole for grafting in the only eye with failed vascularised graft. It was the only possibility for this patient to restore some vision.

Enucleaton of the right eye due to large choroidal melanoma with simultaneous penetrating cornea transplantation from OD to OS (Case report.

Directory of Open Access Journals (Sweden)

E. A. Korchuganova

2014-07-01

Full Text Available There is presentation case report of 75‑year old woman with choroidal melanoma (T3N0M0 on the right eye and failed graft on the left pseudophakic eye with far advanced glaucoma and ARMD. No treatment was given to the leading eye with VA 0,2. VA of OS = 1 / ∞ pr.l.certa; PKP OS in 2008 for pseudophakic bullous keratopathy on the eye with far advanced glaucoma. IOP was normal after previous filtering surgery. After PKP VA = 0,04; clear graft during 2 years; then gradually opacification and vascularization occurred. VA dropped to light perception. Echography OD — tumor h 8,29 mm, d 21,77 mm. No ingrowth of tumor into anterior segment of the eye; VA OD = 0 (no light perception. Concerning the need to enucleate the right eye with large choroidal melanoma, the advantage of using corneal autograft from OD to OS, location of tumor in the posterior pole with no ingrowth in anterior segment, the decision was made to perform the following operation — to enucleate the right eye and transplant simultaneously corneal graft from OD on OS. Patient was discharged from the Ophthalmology Hospital with VA OS = 0,01, during next week VA improved to 0,02. 8,0 mm graft isclear, fixed with 8 interruptured and continious suture 10 / 0‑nylon. Anterior chamber — normal depth, atrophic iris, stable position of PC IOL. Optic nerve head is pale with subtotal deep glaucomatous excavation. Conclusion: presented case report demonstrates the rarepossibility to use cornea after enucleation the eye with large malignant tumor (located in the posterior pole for grafting in the only eye with failed vascularised graft. It was the only possibility for this patient to restore some vision.

The Effect of Systemic Amantadine Sulfate on Malondialdehyde and Total Thiol Levels in Rat Corneas

Directory of Open Access Journals (Sweden)

Züleyha Yalniz-Akkaya

2014-01-01

Full Text Available Purpose: To evaluate the malondialdehyde (MDA and total thiol (sulfhydryl, SH levels in rat corneas after intraperitoneal injection of amantadine sulfate. Methods: A total of 12 Wistar albino rats were divided into two groups: control group (n = 6 and amantadine group (n = 6. Balanced salt solution (1 mL, 0.9% NaCl, twice/day was injected into rats in control group. Amantadine sulfate (2 mg/1 mL, twice/day was injected into rats in amantadine group. In each group, two rats were injected for 1 week, two received injections for 1 month, and two rats received injections for 3 months. The corneas were homogenized and MDA and SH levels were measured spectroflourometrically. Results: In control group, median MDA and SH levels were 2.37 (range, 0.92-3.60 and 25.35 (range, 6.30-54.0 nmol/mg, respectively. In amantadine group, median MDA and SH levels were 3.57 (range, 1.25-5.92 and 32.65 (range, 3.30-48.3 nmol/mg, respectively. The difference between this two groups regarding MDA (P = 0.14 and SH (P = 1.0 levels was statistically insignificant. Conclusion: Systemically administered amantadine sulfate seems not to cause MDA and SH imbalance in rat corneas.

Rocking media over ex vivo corneas improves this model and allows the study of the effect of proinflammatory cytokines on wound healing.

Science.gov (United States)

Deshpande, Pallavi; Ortega, Ílida; Sefat, Farshid; Sangwan, Virender S; Green, Nicola; Claeyssens, Frederik; MacNeil, Sheila

2015-02-05

The aim of this work was to develop an in vitro cornea model to study the effect of proinflammatory cytokines on wound healing. Initial studies investigated how to maintain the ex vivo models for up to 4 weeks without loss of epithelium. To study the effect of cytokines, corneas were cultured with the interleukins IL-17A, IL-22, or a combination of IL-17A and IL-22, or lipopolysaccharide (LPS). The effect of IL-17A on wound healing was then examined. With static culture conditions, organ cultures deteriorated within 2 weeks. With gentle rocking of media over the corneas and carbon dioxide perfusion, the ex vivo models survived for up to 4 weeks without loss of epithelium. The cytokine that caused the most damage to the cornea was IL-17A. Under static conditions, wound healing of the central corneal epithelium occurred within 9 days, but only a single-layered epithelium formed whether the cornea was exposed to IL-17A or not. With rocking of media gently over the corneas, a multilayered epithelium was achieved 9 days after wounding. In the presence of IL-17A, however, there was no wound healing evident. Characterization of the cells showed that wherever epithelium was present, both differentiated cells and highly proliferative cells were present. We propose that introducing rocking to extend the effective working life of this model and the introduction of IL-17A to this model to induce aspects of inflammation extend its usefulness to study the effects of agents that influence corneal regeneration under normal and inflamed conditions. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

Brittle Cornea Syndrome Associated with a Missense Mutation in the Zinc-Finger 469 Gene

DEFF Research Database (Denmark)

Christensen, Anne Elisabeth; Knappskog, Per Morten; Midtbø, Marit

2010-01-01

Purpose: To investigate the diverse clinical manifestations, identify the causative mutation and explain the association with red hair in a family with brittle cornea syndrome (BCS). Methods: Eight family members in three generations underwent ophthalmic, dental, and general medical examination...... mapping with SNP markers, DNA sequencing, and MC1R genotyping. Results: At 42 and 48 years of age, respectively, both affected individuals were blind due to retinal detachment and secondary glaucoma. They had extremely thin and bulging corneas, velvety skin, chestnut colored hair, scoliosis, reduced BMD......, dental anomalies, hearing loss and minor cardiac defects. The morphologies of the skin biopsies were normal except that in some areas slightly thinner collagen fibrils were seen in one of the affected individuals. Molecular genetic analysis revealed a novel missense mutation of ZNF469, c.10016G...

Clinical and epidemiological aspects of cornea transplant patients of a reference hospital.

Science.gov (United States)

Cruz, Giovanna Karinny Pereira; Azevedo, Isabelle Campos de; Carvalho, Diana Paula de Souza Rego Pinto; Vitor, Allyne Fortes; Santos, Viviane Euzébia Pereira; Ferreira, Marcos Antonio

2017-06-08

clinically characterizing cornea transplant patients and their distribution according to indicated and post-operative conditions of cornea transplantation, as well as estimating the average waiting time. a cross-sectional, descriptive and analytical study performed for all cornea transplants performed at a reference service (n=258). Data were analyzed using Statistical Package for the Social Sciences, version 20.0. the main indicator for cornea transplant was keratoconus. The mean waiting time for the transplant was approximately 5 months and 3 weeks for elective transplants and 9 days for urgent cases. An association between the type of corneal disorder with gender, age, previous surgery, eye classification, glaucoma and anterior graft failure were found. keratoconus was the main indicator for cornea transplant. Factors such as age, previous corneal graft failure (retransplantation), glaucoma, cases of surgeries prior to cornea transplant (especially cataract surgery) may be related to the onset corneal endothelium disorders. caracterizar clínicamente los pacientes trasplantados y su distribución, con descripción de las condiciones indicadoras y posoperatorias de los trasplantes de córneas, así como estimar el tiempo promedio en la fila de espera. estudio epidemiológico, transversal, descriptivo y analítico, realizado con todos los trasplantes de córnea realizados en un servicio de referencia (n=258). Los datos fueron analizados con el software Statistical Package for the Social Sciences, versión 20.0. la principal condición indicadora para el trasplante de córnea fue el queratocono. El tiempo promedio en fila de espera para realización del trasplante fue de aproximadamente 5 meses y tres semanas, para trasplantes electivos y de 9 días para los casos de urgencia. Existió asociación entre el tipo de disturbio de la córnea con: sexo, intervalo etario, cirugía previa, clasificación del ojo, glaucoma y rechazo del injerto anterior. el queratocono fue

Image enhancement by spatial frequency post-processing of images obtained with pupil filters

Science.gov (United States)

Estévez, Irene; Escalera, Juan C.; Stefano, Quimey Pears; Iemmi, Claudio; Ledesma, Silvia; Yzuel, María J.; Campos, Juan

2016-12-01

The use of apodizing or superresolving filters improves the performance of an optical system in different frequency bands. This improvement can be seen as an increase in the OTF value compared to the OTF for the clear aperture. In this paper we propose a method to enhance the contrast of an image in both its low and its high frequencies. The method is based on the generation of a synthetic Optical Transfer Function, by multiplexing the OTFs given by the use of different non-uniform transmission filters on the pupil. We propose to capture three images, one obtained with a clear pupil, one obtained with an apodizing filter that enhances the low frequencies and another one taken with a superresolving filter that improves the high frequencies. In the Fourier domain the three spectra are combined by using smoothed passband filters, and then the inverse transform is performed. We show that we can create an enhanced image better than the image obtained with the clear aperture. To evaluate the performance of the method, bar tests (sinusoidal tests) with different frequency content are used. The results show that a contrast improvement in the high and low frequencies is obtained.

Cornea and anterior eye assessment with placido-disc keratoscopy, slit scanning evaluation topography and scheimpflug imaging tomography.

Science.gov (United States)

Martin, Raul

2018-03-01

Current corneal assessment technologies make the process of corneal evaluation extremely fast and simple and several devices and technologies allow to explore and to manage patients. The purpose of this special issue is to present and also to update in the evaluation of cornea and ocular surface and this second part, reviews a description of the corneal topography and tomography techniques, providing updated information of the clinical recommendations of these techniques in eye care practice. Placido-based topographers started an exciting anterior corneal surface analysis that allows the development of current corneal tomographers that provide a full three-dimensional reconstruction of the cornea including elevation, curvature, and pachymetry data of anterior and posterior corneal surfaces. Although, there is not an accepted reference standard technology for corneal topography description and it is not possible to determine which device produces the most accurate topographic measurements, placido-based topographers are a valuable technology to be used in primary eye care and corneal tomograhers expanding the possibilities to explore cornea and anterior eye facilitating diagnosis and follow-up in several situations, raising patient follow-up, and improving the knowledge regarding to the corneal anatomy. Main disadvantages of placido-based topographers include the absence of information about the posterior corneal surface and limited corneal surface coverage without data from the para-central and/or peripheral corneal surface. However, corneal tomographers show repeatable anterior and posterior corneal surfaces measurements, providing full corneal thickness data improving cornea, and anterior surface assessment. However, differences between devices suggest that they are not interchangeable in clinical practice.

Eye evolution: lens and cornea as an upgrade of animal visual system

Czech Academy of Sciences Publication Activity Database

Jonášová, Kristýna; Kozmik, Zbyněk

2008-01-01

Roč. 19, č. 2 (2008), s. 71-81 ISSN 1084-9521 R&D Projects: GA AV ČR IAA500520604; GA MŠk(CZ) 1M0520 Institutional research plan: CEZ:AV0Z50520514 Keywords : eye * lens * cornea Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.528, year: 2008

Pathways and Mechanisms Underlying the Photophysics and Photochemistry of Riboflavin induced cornea crosslinking

DEFF Research Database (Denmark)

Breitenbach, Thomas; Ogilby, Peter Remsen

In this talk, we will describe general pathways involved in the photophysics of a photosensitized process, which can lead to crosslinking due to light excitation of Riboflavin in the cornea. Furthermore, we will elucidate different aspects of reactions that can produce crosslinks, with respect...

The 2D Hotelling filter - a quantitative noise-reducing principal-component filter for dynamic PET data, with applications in patient dose reduction

International Nuclear Information System (INIS)

Axelsson, Jan; Sörensen, Jens

2013-01-01

In this paper we apply the principal-component analysis filter (Hotelling filter) to reduce noise from dynamic positron-emission tomography (PET) patient data, for a number of different radio-tracer molecules. We furthermore show how preprocessing images with this filter improves parametric images created from such dynamic sequence. We use zero-mean unit variance normalization, prior to performing a Hotelling filter on the slices of a dynamic time-series. The Scree-plot technique was used to determine which principal components to be rejected in the filter process. This filter was applied to [ 11 C]-acetate on heart and head-neck tumors, [ 18 F]-FDG on liver tumors and brain, and [ 11 C]-Raclopride on brain. Simulations of blood and tissue regions with noise properties matched to real PET data, was used to analyze how quantitation and resolution is affected by the Hotelling filter. Summing varying parts of a 90-frame [ 18 F]-FDG brain scan, we created 9-frame dynamic scans with image statistics comparable to 20 MBq, 60 MBq and 200 MBq injected activity. Hotelling filter performed on slices (2D) and on volumes (3D) were compared. The 2D Hotelling filter reduces noise in the tissue uptake drastically, so that it becomes simple to manually pick out regions-of-interest from noisy data. 2D Hotelling filter introduces less bias than 3D Hotelling filter in focal Raclopride uptake. Simulations show that the Hotelling filter is sensitive to typical blood peak in PET prior to tissue uptake have commenced, introducing a negative bias in early tissue uptake. Quantitation on real dynamic data is reliable. Two examples clearly show that pre-filtering the dynamic sequence with the Hotelling filter prior to Patlak-slope calculations gives clearly improved parametric image quality. We also show that a dramatic dose reduction can be achieved for Patlak slope images without changing image quality or quantitation. The 2D Hotelling-filtering of dynamic PET data is a computer

[Current approaches to evaluating the anatomic and functional status of the cornea].

Science.gov (United States)

Avetisov, S E; Borodina, N V; Kobzova, M V; Musaeva, G M

2010-01-01

The review provides data on current methods for evaluating the anatomic and functional status of the cornea (light refraction, light transmission, and biomechanical properties, in particular). It analyzes the main advantages and disadvantages of basic (biomicroscopy, endothelial microscopy, ophthalmometry, topography, and pachymetry) and special (confocal microscopy, optical coherence tomography, ultrasound biomicroscopy, aberrometry, bidirectional corneal applanation, and keratoesthesiometry) studies.

Exploration of alternative test methods to evaluate phototoxicity of ophthalmic agents by using Statens Seruminstitut Rabbit Cornea cell lines and 3D human reconstituted cornea models.

Directory of Open Access Journals (Sweden)

Soyoung Kim

Full Text Available Many chemicals have been reported to induce phototoxicity. The absorbance of light energy within the sunlight range is a common characteristic of phototoxicity. The 3T3 NRU phototoxicity test (PT in 3T3 mouse skin fibroblasts has been used to identify the phototoxic potential induced by excited chemicals after exposure to ultra violet (UV. However, as phototoxicity may occur in ocular cells, it is necessary to develop a more suitable test for cornea-derived cells. In this study, we attempted to establish a new in vitro PT method in rabbit corneal cell lines (SIRC. We evaluated five ophthalmic agents, ciprofloxacin, levofloxacin, lomefloxacin, norfloxacin, and tetracycline, for their cytotoxic potential and in vitro phototoxicity. The results obtained using 3D human corneal models revealed that the UV-induced eye tissue toxicity by the test substances showed good correlation with those obtained using the in vitro phototoxicity test. However, the results from the 3D PT for ciprofloxacin, norfloxacin, and tetracycline in the 3D human cornea model were only partially comparable. Therefore, we suggest the SIRC cell line as a new phototoxicity test model; however, a sequential testing strategy, such as 3D PT, was also proposed to obtain relevant information for topical eye agents.

Transcriptome Profiling of Neovascularized Corneas Reveals miR-204 as a Multi-target Biotherapy Deliverable by rAAVs

Directory of Open Access Journals (Sweden)

Yi Lu

2018-03-01

Full Text Available Corneal neovascularization (NV is the major sight-threatening pathology caused by angiogenic stimuli. Current drugs that directly target pro-angiogenic factors to inhibit or reverse the disease require multiple rounds of administration and have limited efficacies. Here, we identify potential anti-angiogenic corneal microRNAs (miRNAs and demonstrate a framework that employs discovered miRNAs as biotherapies deliverable by recombinant adeno-associated viruses (rAAVs. By querying differentially expressed miRNAs in neovascularized mouse corneas induced by alkali burn, we have revealed 39 miRNAs that are predicted to target more than 5,500 differentially expressed corneal mRNAs. Among these, we selected miR-204 and assessed its efficacy and therapeutic benefit for treating injured corneas. Our results show that delivery of miR-204 by rAAV normalizes multiple novel target genes and biological pathways to attenuate vascularization of injured mouse cornea. Importantly, this gene therapy treatment alternative is efficacious and safe for mitigating corneal NV. Overall, our work demonstrates the discovery of potential therapeutic miRNAs in corneal disorders and their translation into viable treatment alternatives.

Public Health Implications of the 1540 nm Laser on the Cornea

Science.gov (United States)

2007-05-30

of Public Health Degree 30 May 2007 - Thomas J01vfson, Ph.D. Department of Preventive Medicine & Biometrics Committee Member Christine Kasper, ’,D...Xu and Alfano 2005) This absorption characteristic is useful in refractive surgery of the eye because the cornea is approximately 80% water...retina. Invest Ophthalmol Vis Sci 35: 3032-44; 1994. Xu M, Alfano RR. Fractal mechanisms of light scattering in biological tissue and cells. Opt

VRP09 Reduction of Corneal Scarring Following Blast and Burn Injuries to Cornea Using siRNAs Targeting TGFb and CTGF

Science.gov (United States)

2013-03-01

aSMA ) synthesis. Second, we proposed to develop an advanced ex vivo organ culture system using viable explants of rabbit corneas, and assess the...effect of the most effective triple siRNA combination for reduction of target genes, collagen and alpha smooth muscle actin ( aSMA ) in rabbit corneas...targeting three key genes (TGFb, TGFbRII, and CTGF) that synergistically reduces the level of mRNAs for type I collagen gene and aSMA by >95% without

Entertainment-education and recruitment of cornea donors: the role of emotion and issue involvement.

Science.gov (United States)

Bae, Hyuhn-Suhck

2008-01-01

This study examined the role of emotional responses and viewer's level of issue involvement to an entertainment-education show about cornea donation in order to predict intention to register as cornea donors. Results confirmed that sympathy and empathy responses operated as a catalyst for issue involvement, which emerged as an important intermediary in the persuasion process. Issue involvement also was found to be a common causal antecedent of attitude, subjective norm, and perceived behavioral control, the last two of which predict intentions unlike attitude, which does not. The revised path model confirmed that involvement directly influences intention. The findings of this study suggest that adding emotion and involvement in the Theory of Planned Behavior (TPB) enhances the explanatory power of the theory in predicting intentions, which indicates the possibility of combining the Elaboration Likelihood Model (ELM) and the TPB in the prediction of human behaviors.

Desiccating Stress-Induced MMP Production and Activity Worsens Wound Healing in Alkali-Burned Corneas

Science.gov (United States)

Bian, Fang; Pelegrino, Flavia S. A.; Pflugfelder, Stephen C.; Volpe, Eugene A.; Li, De-Quan; de Paiva, Cintia S.

2015-01-01

Purpose To evaluate the effects of dry eye on ocular surface protease activity and sight threatening corneal complications following ocular surface chemical injury. Methods C57BL/6 mice were subjected to unilateral alkali burn (AB) with or without concomitant dry eye for 2 or 5 days. Mice were observed daily for appearance of corneal perforation. Whole corneas were harvested and lysed for RNA extraction. Quantitative real-time PCR was performed to measure expression of inflammation cytokines, matrix metalloproteinases (MMP). Matrix metalloproteinase–9 activity, gelatinase activity, and myeloperoxidase (MPO) activity were evaluated in corneal lysates. Presence of infiltrating neutrophils was evaluated by immunohistochemistry and flow cytometry. Results Eyes subjected to the combined model of AB and dry eye (CM) had 20% sterile corneal perforation rate as soon as 1 day after the initial injury, which increased to 35% by 5 days, delayed wound closure and increased corneal opacity. Increased levels of IL-1β, -6, and MMPs-1, -3, -8, -9, and -13, and chemokine (C-X-C motif) ligand 1 (CSCL1) transcripts were found after 2 days in CM compared with AB corneas. Increased MMP-1, -3, -9, and -13 immunoreactivity and gelatinolytic activity were seen in CM corneas compared with AB. Increased neutrophil infiltration and MPO activity was noted in the CM group compared with AB 2 days post injury. Conclusions Desiccating stress worsens outcome of ocular AB, creating a cytokine and protease storm with greater neutrophil infiltration, increasing the risk of corneal perforation. PMID:26225631

T-style keratoprosthesis based on surface-modified poly (2-hydroxyethyl methacrylate) hydrogel for cornea repairs

International Nuclear Information System (INIS)

Xiang, Jun; Sun, Jianguo; Hong, Jiaxu; Wang, Wentao; Wei, Anji; Le, Qihua; Xu, Jianjiang

2015-01-01

Corneal disease is a common cause of blindness, and keratoplasty is considered as an effective treatment method. However, there is a severe shortage of donor corneas worldwide. This paper presents a novel T-style design of a keratoprosthesis and its preparation methods, in which a mechanically and structurally effective artificial cornea is made based on a poly(2-hydroxyethyl methacrylate) hydrogel. The porous skirt was modified with hyaluronic acid and cationized gelatin, and the bottom of the optical column was coated with poly(ethylene glycol). The physical properties of the T-style Kpro were analyzed using ultraviolet and visible spectrophotometry and electron scanning microscopy. The surface chemical properties were characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface modification in the spongy skirt promoted cell adhesion and produced a firm bond between the corneal tissue and the implant device, while the surface modification in the optic column resisted cell adhesion and prevented retroprosthetic membrane formation. Through improved surgical techniques, the novel T-style keratoprosthesis provides enough mechanical stability to facilitate long-term biointegration with the host environment. In vivo implantation experiments showed that the T-style keratoprosthesis is a promising cornea alternative for patients with severe limbal stem cell deficiency and corneal opacity. - Highlights: • T-style keratoprosthesis was designed and prepared based on a PHEMA hydrogel. • Selective surface modifications effectively regulated cells' selective adhesion. • T-style keratoprosthesis provides enough mechanical stability to facilitate long-term biointegration with host tissues

T-style keratoprosthesis based on surface-modified poly (2-hydroxyethyl methacrylate) hydrogel for cornea repairs

Energy Technology Data Exchange (ETDEWEB)

Xiang, Jun [Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China); Sun, Jianguo [Research Center, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China); State Key Laboratory of Molecular Engineering of Polymers, Fudan University (China); Hong, Jiaxu [Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China); Wang, Wentao [Research Center, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China); Wei, Anji [Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China); Le, Qihua [Research Center, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China); Xu, Jianjiang, E-mail: jianjiang-xu@163.com [Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University (China); Key Laboratory of Myopia, Ministry of Health, Fudan University (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University (China)

2015-05-01

Corneal disease is a common cause of blindness, and keratoplasty is considered as an effective treatment method. However, there is a severe shortage of donor corneas worldwide. This paper presents a novel T-style design of a keratoprosthesis and its preparation methods, in which a mechanically and structurally effective artificial cornea is made based on a poly(2-hydroxyethyl methacrylate) hydrogel. The porous skirt was modified with hyaluronic acid and cationized gelatin, and the bottom of the optical column was coated with poly(ethylene glycol). The physical properties of the T-style Kpro were analyzed using ultraviolet and visible spectrophotometry and electron scanning microscopy. The surface chemical properties were characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface modification in the spongy skirt promoted cell adhesion and produced a firm bond between the corneal tissue and the implant device, while the surface modification in the optic column resisted cell adhesion and prevented retroprosthetic membrane formation. Through improved surgical techniques, the novel T-style keratoprosthesis provides enough mechanical stability to facilitate long-term biointegration with the host environment. In vivo implantation experiments showed that the T-style keratoprosthesis is a promising cornea alternative for patients with severe limbal stem cell deficiency and corneal opacity. - Highlights: • T-style keratoprosthesis was designed and prepared based on a PHEMA hydrogel. • Selective surface modifications effectively regulated cells' selective adhesion. • T-style keratoprosthesis provides enough mechanical stability to facilitate long-term biointegration with host tissues.

Experimental study on the healing process following laser welding of the cornea.

Science.gov (United States)

Rossi, Francesca; Pini, Roberto; Menabuoni, Luca; Mencucci, Rita; Menchini, Ugo; Ambrosini, Stefano; Vannelli, Gabriella

2005-01-01

An experimental study evaluating the application of laser welding of the cornea and the subsequent healing process is presented. The welding of corneal wounds is achieved after staining the cut walls with a solution of the chromophore indocyanine green, and irradiating them with a diode laser (810 nm) operating at low power (60 to 90 mW). The result is a localized heating of the cut, inducing controlled welding of the stromal collagen. In order to optimize this technique and to study the healing process, experimental tests, simulating cataract surgery and penetrating keratoplasty, were performed on rabbits: conventional and laser-induced suturing of corneal wounds were thus compared. A follow-up study 7 to 90 days after surgery was carried out by means of objective and histological examinations, in order to optimize the welding technique and to investigate the subsequent healing process. The analyses of the laser-welded corneas evidenced a faster and more effective restoration of the architecture of the stroma. No thermal damage of the welded stroma was detected, nor were there foreign body reactions or other inflammatory processes. Copyright 2005 Society of Photo-Optical Instrumentation Engineers.

The management of cornea blindness from severe corneal scarring, with the Athens Protocol (transepithelial topography-guided PRK therapeutic remodeling, combined with same-day, collagen cross-linking

Directory of Open Access Journals (Sweden)

Kanellopoulos AJ

2012-02-01

Full Text Available Anastasios John KanellopoulosLaservision.gr Institute, Athens, Greece; Manhattan Eye, Ear and Throat Hospital, New York, NY, USA; New York University Medical School, New York, NY, USAPurpose: To evaluate the safety and efficacy of combined transepithelial topography-guided photorefractive keratectomy (PRK therapeutic remodeling, combined with same-day, collagen cross-linking (CXL. This protocol was used for the management of cornea blindness due to severe corneal scarring.Methods: A 57-year-old man had severe corneal blindness in both eyes. Both corneas had significant central scars attributed to a firework explosion 45 years ago, when the patient was 12 years old. Corrected distance visual acuity (CDVA was 20/100 both eyes (OU with refraction: +4.00, –4.50 at 135° in the right eye and +3.50, –1.00 at 55° in the left. Respective keratometries were: 42.3, 60.4 at 17° and 35.8, 39.1 at 151.3°. Cornea transplantation was the recommendation by multiple cornea specialists as the treatment of choice. We decided prior to considering a transplant to employ the Athens Protocol (combined topography-guided partial PRK and CXL in the right eye in February 2010 and in the left eye in September 2010. The treatment plan for both eyes was designed on the topography-guided wavelight excimer laser platform.Results: Fifteen months after the right eye treatment, the right cornea had improved translucency and was topographically stable with uncorrected distance visual acuity (UDVA 20/50 and CDVA 20/40 with refraction +0.50, –2.00 at 5°. We noted a similar outcome after similar treatment applied in the left eye with UDVA 20/50 and CDVA 20/40 with –0.50, –2.00 at 170° at the 8-month follow-up.Conclusion: In this case, the introduction of successful management of severe cornea abnormalities and scarring with the Athens Protocol may provide an effective alternative to other existing surgical or medical options.Keywords: Athens Protocol, collagen cross

Pathogenic strains of Acanthamoeba are recognized by TLR4 and initiated inflammatory responses in the cornea.

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Hassan Alizadeh

Full Text Available Free-living amoebae of the Acanthamoeba species are the causative agent of Acanthamoeba keratitis (AK, a sight-threatening corneal infection that causes severe pain and a characteristic ring-shaped corneal infiltrate. Innate immune responses play an important role in resistance against AK. The aim of this study is to determine if Toll-like receptors (TLRs on corneal epithelial cells are activated by Acanthamoeba, leading to initiation of inflammatory responses in the cornea. Human corneal epithelial (HCE cells constitutively expressed TLR1, TLR2, TLR3, TLR4, and TLR9 mRNA, and A. castellanii upregulated TLR4 transcription. Expression of TLR1, TLR2, TLR3, and TLR9 was unchanged when HCE cells were exposed to A. castellanii. IL-8 mRNA expression was upregulated in HCE cells exposed to A. castellanii. A. castellanii and lipopolysaccharide (LPS induced significant IL-8 production by HCE cells as measured by ELISA. The percentage of total cells positive for TLR4 was higher in A. castellanii stimulated HCE cells compared to unstimulated HCE cells. A. castellanii induced upregulation of IL-8 in TLR4 expressing human embryonic kidney (HEK-293 cells, but not TLR3 expressing HEK-293 cells. TLR4 neutralizing antibody inhibited A. castellanii-induced IL-8 by HCE and HEK-293 cells. Clinical strains but not soil strains of Acanthamoeba activated TLR4 expression in Chinese hamster corneas in vivo and in vitro. Clinical isolates but not soil isolates of Acanthamoeba induced significant (P< 0.05 CXCL2 production in Chinese hamster corneas 3 and 7 days after infection, which coincided with increased inflammatory cells in the corneas. Results suggest that pathogenic species of Acanthamoeba activate TLR4 and induce production of CXCL2 in the Chinese hamster model of AK. TLR4 may be a potential target in the development of novel treatment strategies in Acanthamoeba and other microbial infections that activate TLR4 in corneal cells.

One cornea for two patients: case report Uma córnea para dois pacientes: relato de caso

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Ljubisa Nikolic

2010-06-01

Full Text Available Case reporting the use of one donor cornea for two transplantation procedures: deep anterior lamellar keratoplasty (DALK in a case of an imminent corneal perforation caused by herpetic stromal necrosis, and Descemet stripping with endothelial keratoplasty (DSEK in an eye with pseudophakic bullous keratopathy (PBK. Descemet's membrane (DM, denuded by stromal necrosis, served as the starting point for dissection plane and creation of the recipient bed for DALK. The next steps were excision of the diseased stroma along the edge of trephination, and transplantation of a 400-450 µm thick, manually dissected lamellar graft. The remaining posterior layers of the donor cornea, 100-150 µm thick, were used as a graft in the DSEK procedure for PBK. The integrity of the globe was saved, and best-corrected visual acuity (BCVA of 20/40 was reached after DALK in the eye with an imminent corneal perforation. A subnormal central corneal thickness (CCT of 430 µm did not interfere with corneal shape (43.50 x 45.50 D and function. The graft remained attached and clear after DSEK in the eye with PBK, with BCVA of 20/30 and a CCT of 653 µm. One donor cornea can be used for two lamellar keratoplasties, DALK and DSEK. Although the described obstacles may prevent this approach from becoming widely used, it may prove useful when one is confronted with a need for an urgent anterior lamellar keratoplasty, a long list of cases for DSEK, and a shortage of donor corneas.Relato de caso descrevendo o uso de uma córnea doadora para dois procedimentos de transplante: ceratoplastia anterior lamelar profunda (DALK no caso de uma perfuração corneal iminente causada por necrose estromal por herpes vírus, e ceratoplastia com transplante de endotélio (DSEK no olho com ceratopatia bolhosa em pseudofacia (PBK. A membrana de Descemet (DM, previamente desnudada pela necrose estromal, serviu como ponto de partida para o plano de dissecção e da criação do leito estromal para

Modified Descemet’s Stripping Automated Endothelial Keratoplasty: The Use of Ophthalmic Viscoelastic Devices in Hypotonic Eyes That Had Undergone Glaucoma Filtering Surgeries

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Itaru Oyakawa

2018-01-01

Full Text Available Purpose. Descemet’s stripping automated endothelial keratoplasty (DSAEK is more difficult in hypotonic eyes with filtering bleb, due to the difficulties in elevating the intraocular pressure (IOP. We report a new method that uses ophthalmic viscoelastic devices (OVDs to achieve good graft adhesion. Case Presentation. We performed modified DSAEK surgery on 2 eyes of 2 patients, who had previously undergone a trabeculectomy. Both eyes had functioning filtering blebs; the IOP was lower than 10 mmHg without medication. After the graft was inserted into the anterior chamber, the conjunctiva was penetrated, apart from the bleb, using a 30 G needle, and Healon V® was injected into the bleb until the encapsulated space was filled completely. Air was subsequently injected into the anterior chamber to promote the graft attachment to the back surface of the cornea. The IOP was elevated above 40 mmHg in both eyes 1 h after surgery and then decreased to less than 30 mmHg over the subsequent 3 h period. The implanted graft showed good adhesion and no dislocation. Conclusions. Our novel DSAEK procedure that adds one step of OVD injection into the filtering bleb may be useful for hypotonic eyes that had undergone filtering surgeries.

Effect of irradiation and cystamine on the secondary induction of cornea in anura larvae

International Nuclear Information System (INIS)

Popov, D.V.; Starodubov, S.M.

1977-01-01

Secondary induction of cornea in the transplanted skin has been studied in amphibian larvae after the effect of irradiation and cystamine on the recipients and donors. Comparison of the results obtained with those reported earlier has demonstrated that the irradiated tissue is more responsive to inductive effects than the intact one

Biofunctionalized Lysophosphatidic Acid/Silk Fibroin Film for Cornea Endothelial Cell Regeneration

Science.gov (United States)

Jeon, Hayan; Oliveira, Joaquim Miguel; Reis, Rui Luis; Khang, Gilson

2018-01-01

Cornea endothelial cells (CEnCs) tissue engineering is a great challenge to repair diseased or damaged CEnCs and require an appropriate biomaterial to support cell proliferation and differentiation. Biomaterials for CEnCs tissue engineering require biocompatibility, tunable biodegradability, transparency, and suitable mechanical properties. Silk fibroin-based film (SF) is known to meet these factors, but construction of functionalized graft for bioengineering of cornea is still a challenge. Herein, lysophosphatidic acid (LPA) is used to maintain and increase the specific function of CEnCs. The LPA and SF composite film (LPA/SF) was fabricated in this study. Mechanical properties and in vitro studies were performed using a rabbit model to demonstrate the characters of LPA/SF. ATR-FTIR was characterized to identify chemical composition of the films. The morphological and physical properties were performed by SEM, AFM, transparency, and contact angle. Initial cell density and MTT were performed for adhesion and cell viability in the SF and LPA/SF film. Reverse transcription polymerase chain reactions (RT-PCR) and immunofluorescence were performed to examine gene and protein expression. The results showed that films were designed appropriately for CEnCs delivery. Compared to pristine SF, LPA/SF showed higher biocompatibility, cell viability, and expression of CEnCs specific genes and proteins. These indicate that LPA/SF, a new biomaterial, offers potential benefits for CEnCs tissue engineering for regeneration. PMID:29710848

Molecular Hydrogen Effectively Heals Alkali-Injured Cornea via Suppression of Oxidative Stress

Czech Academy of Sciences Publication Activity Database

Čejka, Čestmír; Kössl, Jan; Heřmánková, Barbora; Holáň, Vladimír; Čejková, Jitka

2017-01-01

Roč. 2017, č. 2017 (2017), s. 8906027 ISSN 1942-0900 R&D Projects: GA ČR(CZ) GA14-12580S; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) LO1508; GA MŠk(CZ) LO1309 Institutional support: RVO:68378041 Keywords : 4-coumaric acid * rabbit cornea * nitric-oxide Subject RIV: FF - HEENT, Dentistry OBOR OECD: Ophthalmology Impact factor: 4.593, year: 2016

The role of corneal endothelial morphology in graft assessment and prediction of endothelial cell loss during organ culture of human donor corneas.

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Hermel, Martin; Salla, Sabine; Fuest, Matthias; Walter, Peter

2017-03-01

Endothelial assessment is crucial in the release of corneas for grafting. We retrospectively analysed the role of endothelial morphology parameters in predicting endothelial cell loss during organ culture. Human donor corneas were cultured in minimal essential medium with 2% fetal calf serum and antibiotics. Initial endothelial morphology was assessed microscopically using score parameters polymegethism (POL), pleomorphism (PLE), granulation (GRA), vacuolization (VAC), segmentation of cell membranes (SEG), Descemet's folds (DF), trypan blue-positive cells (TBPC) and endothelial cell-free areas (ECFA). Some corneas were primarily rejected based on endothelial assessment. Endothelial cell density (ECD) was assessed at the beginning (I-ECD) and end of culture. Corneas were then placed in dehydration medium (as above + 5% dextran 500). In a subgroup, ECD was reassessed after dehydration. Endothelial cell loss during culture (ECL@Culture) and culture+dehydration (ECL-Culture&Dehydration) were calculated. Data were given as mean ± SD and analysed using multiple linear and logistic regression. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. I-ECD was 2812 ± 360/mm 2 (n = 2356). The decision to reject a cornea due to endothelial assessment was associated negatively with I-ECD (OR = 0.77/100 cells, CI 0.7-0.82) and positively with ECFA (OR = 2.7, CI 1.69-4.35), SEG (OR =1.3, CI 1.01-1.68) and donor age (OR = 1.26/decade, CI 1.33-1.41). ECL@Culture was 153 ± 201/mm 2 (n = 1277), ECL@Culture&Dehydration was 169 ± 183/mm 2 (n = 918). ECL@Culture was associated positively with donor age, I-ECD, GRA and TBPC, and negatively with PLE, and DF. ECL@Culture&Dehydration was associated positively with age, sex, initial ECD, POL, PLE, VAC and TBPC. Morphological parameters displayed associations with the exclusion of corneas from culture and with endothelial cell loss. Appropriate parameter selection for screening purposes may help improve

The Resin-Embedded Cornea Prepared Via Rapid Processing Protocol : A Good Histomorphometric Target for Clinical Investigation in Ophthalmology and Optometry

Science.gov (United States)

Cheah, Pike See; Mohidin, Norhani; Mohd Ali, Bariah; Maung, Myint; Latif, Azian Abdul

2008-01-01

This study illustrates and quantifies the changes on corneal tissue between the paraffin-embedded and resin-embedded blocks and thus, selects a better target in investigational ophthalmology and optometry via light microscopy. Corneas of two cynomolgus monkeys (Macaca fascicularis) were used in this study. The formalin-fixed cornea was prepared in paraffin block via the conventional tissue processing protocol (4-day protocol) and stained with haematoxylin and eosin. The glutaraldehyde-fixed cornea was prepared in resin block via the rapid and modified tissue processing procedure (1.2-day protocol) and stained with toluidine blue. The paraffin-embedded sample exhibits various undesired tissue damage and artifact such as thinner epithelium (due to the substantial volumic extraction from the tissue), thicker stroma layer (due to the separation of lamellae and the presence of voids) and the distorted endothelium. In contrast, the resin-embedded corneal tissue has demonstrated satisfactory corneal ultrastructural preservation. The rapid and modified tissue processing method for preparing the resin-embedded is particularly beneficial to accelerate the microscopic evaluation in ophthalmology and optometry. PMID:22570589

The comparative safety of genipin versus UVA-riboflavin crosslinking of rabbit corneas

Science.gov (United States)

Song, Wenjing; Tang, Yun; Qiao, Jing; Li, Haili; Rong, Bei; Yang, Songlin; Wu, Yuan

2017-01-01

Purpose To investigate, after 24 h, the safety of genipin or ultraviolet A (UVA)-riboflavin crosslinking of keratocytes and endothelial cells. Methods Fifteen New Zealand white rabbits were selected and divided into a PBS group (five rabbits), a 0.2% genipin crosslinking (GP-CXL) group (five rabbits), and a UVA-riboflavin crosslinking (UVA-CXL) group (five rabbits). In the GP-CXL and PBS groups, 0.2% genipin or PBS was applied to the corneal surface of the right eyes. In the UVA-CXL group, a clinical crosslinking procedure was used. Before and after surgery, the operated eyes of each group were characterized with confocal microscopy, and the corneal buttons were excised for endothelium staining and electron microscopy. Results The corneal endothelial cell density of the GP-CXL, UVA-CLX, and PBS groups changed. There was a statistically significant difference in thickness and changes in corneal endothelial cell density between the UVA-CXL group and the PBS group (pUVA-CXL group and the GP-CXL group (pUVA-CXL group. In the GP-CXL group, only active keratocytes were found and minimal endothelial cell damage. Conclusions Treatment of rabbit corneas with 0.2% genipin showed minimal toxicity toward keratocytes and endothelial cells. Genipin is safer than UVA-CXL for crosslinking of thin corneas. PMID:28761323

Image restoration by Wiener filtering in the presence of signal-dependent noise.

Science.gov (United States)

Kondo, K; Ichioka, Y; Suzuki, T

1977-09-01

An optimum filter to restore the degraded image due to blurring and the signal-dependent noise is obtained on the basis of the theory of Wiener filtering. Computer simulations of image restoration using signal-dependent noise models are carried out. It becomes clear that the optimum filter, which makes use of a priori information on the signal-dependent nature of the noise and the spectral density of the signal and the noise showing significant spatial correlation, is potentially advantageous.

Cerebral ischemia after filter-protected carotid artery stenting is common and cannot be predicted by the presence of substantial amount of debris captured by the filter device.

Science.gov (United States)

Maleux, G; Demaerel, P; Verbeken, E; Daenens, K; Heye, S; Van Sonhoven, F; Nevelsteen, A; Wilms, G

2006-10-01

Protected carotid artery stent placement is currently under clinical evaluation as a potential alternative to carotid endarterectomy. The current study was undertaken to determine the incidence of new ischemic lesions found on diffusion-weighted MR imaging (DWI) in nonselected patients after protected carotid artery stent placement using a filter device and to determine the potential relationship between these new ischemic lesions and the presence or absence of a clear amount of debris captured by the neuroprotection filter device. A nonrandomized cohort of 52 patients (40 men, 12 women) presenting with carotid occlusive disease underwent protected carotid artery stent placement using a filter device. DWI obtained 1 day before stent placement was compared with that obtained 1 day after stent placement. In addition, the macroscopic and microscopic analysis of debris captured by the filter device during the carotid stent placement procedure was assessed. Neuroprotected carotid stent placement was technically successful in all 53 procedures but was complicated by a transient ischemic attack in 3 patients (5.6%). In 22 patients (41.5%), new ischemic lesions were found on DWI, and in 21 filter devices (39.6%), a substantial amount of atheromatous plaque and/or fibrin was found. No clear relationship between the presence of debris captured by the filter device and new lesions detected by DWI was found (P = .087; odds ratio 3.067). Neuroprotected carotid artery stent placement will not avoid silent cerebral ischemia. Systematic microscopic analysis of debris captured by the filter device has no predictive value for potential cerebral ischemia after carotid artery stent placement.

Collagen cross-linking in thin corneas

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Prema Padmanabhan

2013-01-01

Full Text Available Collagen cross-linking (CXL has become the standard of care for progressive keratoconus, after numerous clinical studies have established its efficacy and safety in suitably selected eyes. The standard protocol is applicable in eyes which have a minimum corneal thickness of 400 μm after epithelial debridement. This prerequisite was stipulated to protect the corneal endothelium and intraocular tissues from the deleterious effect of ultraviolet-A (UVA radiation. However, patients with keratoconus often present with corneal thickness of less than 400 μm and could have otherwise benefited from this procedure. A few modifications of the standard procedure have been suggested to benefit these patients without a compromise in safety. Transepithelial cross-linking, pachymetry-guided epithelial debridement before cross-linking, and the use of hypoosmolar riboflavin are some of the techniques that have been attempted. Although clinical data is limited at the present time, these techniques are worth considering in patients with thin corneas. Further studies are needed to scientifically establish their efficacy and safety.

Proliferative activity of endotheliocytes of growing capillaries of the rabbit cornea

International Nuclear Information System (INIS)

Gurina, O.Yu.; Mamontov, S.G.; Banin, V.V.

1987-01-01

The authors studied the intensity of DNA synthesis by cells of newly formed capillaries, growing in the rabbit cornea, after infliction of a silver nitrate burn and local application of colchicine. The intensity of capillary growth was investigated during stimulation and a combination of the burn with colchicine. Changes in activity of DNA synthesis by the endotheliocytes of newly formed capillaries during exposure throughout growth were also investigated. The intensity of cell proliferation was studied by measuring the incorporation of tritium-labelled thymidine into the endotheoiocyte nuclei

Tissue Engineering the Cornea: The Evolution of RAFT

Science.gov (United States)

Levis, Hannah J.; Kureshi, Alvena K.; Massie, Isobel; Morgan, Louise; Vernon, Amanda J.; Daniels, Julie T.

2015-01-01

Corneal blindness affects over 10 million people worldwide and current treatment strategies often involve replacement of the defective layer with healthy tissue. Due to a worldwide donor cornea shortage and the absence of suitable biological scaffolds, recent research has focused on the development of tissue engineering techniques to create alternative therapies. This review will detail how we have refined the simple engineering technique of plastic compression of collagen to a process we now call Real Architecture for 3D Tissues (RAFT). The RAFT production process has been standardised, and steps have been taken to consider Good Manufacturing Practice compliance. The evolution of this process has allowed us to create biomimetic epithelial and endothelial tissue equivalents suitable for transplantation and ideal for studying cell-cell interactions in vitro. PMID:25809689

The management of cornea blindness from severe corneal scarring, with the Athens Protocol (transepithelial topography-guided PRK therapeutic remodeling, combined with same-day, collagen cross-linking).

Science.gov (United States)

Kanellopoulos, Anastasios John

2012-01-01

To evaluate the safety and efficacy of combined transepithelial topography-guided photorefractive keratectomy (PRK) therapeutic remodeling, combined with same-day, collagen cross-linking (CXL). This protocol was used for the management of cornea blindness due to severe corneal scarring. A 57-year-old man had severe corneal blindness in both eyes. Both corneas had significant central scars attributed to a firework explosion 45 years ago, when the patient was 12 years old. Corrected distance visual acuity (CDVA) was 20/100 both eyes (OU) with refraction: +4.00, -4.50 at 135° in the right eye and +3.50, -1.00 at 55° in the left. Respective keratometries were: 42.3, 60.4 at 17° and 35.8, 39.1 at 151.3°. Cornea transplantation was the recommendation by multiple cornea specialists as the treatment of choice. We decided prior to considering a transplant to employ the Athens Protocol (combined topography-guided partial PRK and CXL) in the right eye in February 2010 and in the left eye in September 2010. The treatment plan for both eyes was designed on the topography-guided wavelight excimer laser platform. Fifteen months after the right eye treatment, the right cornea had improved translucency and was topographically stable with uncorrected distance visual acuity (UDVA) 20/50 and CDVA 20/40 with refraction +0.50, -2.00 at 5°. We noted a similar outcome after similar treatment applied in the left eye with UDVA 20/50 and CDVA 20/40 with -0.50, -2.00 at 170° at the 8-month follow-up. In this case, the introduction of successful management of severe cornea abnormalities and scarring with the Athens Protocol may provide an effective alternative to other existing surgical or medical options.

M2 FILTER FOR SPECKLE NOISE SUPPRESSION IN BREAST ULTRASOUND IMAGES

Directory of Open Access Journals (Sweden)

E.S. Samundeeswari

2016-11-01

Full Text Available Breast cancer, commonly found in women is a serious life threatening disease due to its invasive nature. Ultrasound (US imaging method plays an effective role in screening early detection and diagnosis of Breast cancer. Speckle noise generally affects medical ultrasound images and also causes a number of difficulties in identifying the Region of Interest. Suppressing speckle noise is a challenging task as it destroys fine edge details. No specific filter is designed yet to get a noise free BUS image that is contaminated by speckle noise. In this paper M2 filter, a novel hybrid of linear and nonlinear filter is proposed and compared to other spatial filters with 3×3 kernel size. The performance of the proposed M2 filter is measured by statistical quantity parameters like MSE, PSNR and SSI. The experimental analysis clearly shows that the proposed M2 filter outperforms better than other spatial filters by 2% high PSNR values with regards to speckle suppression.

Moorfields technique of donor cornea mounting for femtosecond-assisted keratoplasty: use of viscoelastic in the artificial anterior chamber.

Science.gov (United States)

Iovieno, Alfonso; Chowdhury, Vivek; Stevens, Julian D; Maurino, Vincenzo

2012-07-01

Appropriate mounting and cutting of the donor sclero-corneal cap is often cumbersome during femtosecond laser-assisted keratoplasty. The authors describe a technique for donor cornea femtosecond laser cutting using ophthalmic viscoelastic devices. The donor sclero-corneal cap is mounted on the artificial anterior chamber using a dispersive ophthalmic viscoelastic device instead of saline solution. The chances of artificial anterior chamber pressure loss, inadequate applanation, and fluid leaks are consistently reduced with the use of dispersive ophthalmic viscoelastic devices. The speed of donor femtosecond laser cutting is increased. The viscosity and elasticity of dispersive ophthalmic viscoelastic devices greatly assist the procedure with regard to ease of applanation, corneal endothelium protection, and decreased distortion of the applanated cornea. Copyright 2012, SLACK Incorporated.

Corneal thickness changes during corneal collagen cross-linking with UV-A irradiation and hypo-osmolar riboflavin in thin corneas

Directory of Open Access Journals (Sweden)

Belquiz Amaral Nassaralla

2013-06-01

Full Text Available PURPOSE: To evaluate the thinnest corneal thickness changes during and after corneal collagen cross-linking treatment with ultraviolet-A irradiation, using hypo-osmolar riboflavin solution in thin corneas. METHODS: Eighteen eyes of 18 patients were included in this study. After epithelium removal, iso-osmolar 0.1% riboflavin solution was instilled to the cornea every 3 minutes for 30 minutes. Hypo-osmolar 0.1% riboflavin solution was then applied every 20 seconds for 5 minutes or until the thinnest corneal thickness reached 400 µm. Ultraviolet-A irradiation was performed for 30 minutes. During irradiation, iso-osmolar 0.1% riboflavin drops were applied every 5 minutes. Ultrasound pachymetry was performed at approximately the thinnest point of the cornea preoperatively, after epithelial removal, after iso-osmolar riboflavin instillation, after hypo-osmolar riboflavin instillation, after ultraviolet-A irradiation, and at 1, 6 and 12 months after treatment. RESULTS: Mean preoperative thinnest corneal thickness was 380 ± 11 µm. After epithelial removal it decreased to 341 ± 11 µm, and after 30 minutes of iso-osmolar 0.1% riboflavin drops, to 330 ± 7.6 µm. After hypo-osmolar 0.1% riboflavin drops, mean thinnest corneal thickness increased to 418 ± 11 µm. After UVA irradiation, it was 384 ± 10 µm. At 1, 6 and 12 months after treatment, it was 372 ± 10 µm, 381 ± 12.7, and 379 ± 15 µm, respectively. No intraoperative, early postoperative, or late postoperative complications were noted. CONCLUSIONS: Hypo-osmolar 0.1% riboflavin solution seems to be effective for swelling thin corneas. The swelling effect is transient and short acting. Corneal thickness should be monitored throughout the procedure. Larger sample sizes and longer follow-up are required in order to make meaningful conclusions regarding safety.

Distribution of Young's modulus in porcine corneas after riboflavin/UVA-induced collagen cross-linking as measured by atomic force microscopy.

Directory of Open Access Journals (Sweden)

Jan Seifert

Full Text Available Riboflavin/UVA-induced corneal collagen cross-linking has become an effective clinical application to treat keratoconus and other ectatic disorders of the cornea. Its beneficial effects are attributed to a marked stiffening of the unphysiologically weak stroma. Previous studies located the stiffening effect predominantly within the anterior cornea. In this study, we present an atomic force microscopy-derived analysis of the depth-dependent distribution of the Young's modulus with a depth resolution of 5 µm in 8 cross-linked porcine corneas and 8 contralateral controls. Sagittal cryosections were fabricated from every specimen and subjected to force mapping. The mean stromal depth of the zone with effective cross-linking was found to be 219 ± 67 µm. Within this cross-linked zone, the mean Young's modulus declined from 49 ± 18 kPa at the corneal surface to 46 ± 17 kPa, 33 ± 11 kPa, 17 ± 5 kPa, 10 ± 4 kPa and 10 ± 4 kPa at stromal depth intervals of 0-50 µm, 50-100 µm, 100-150 µm, 150-200 µm and 200-250 µm, respectively. This corresponded to a stiffening by a factor of 8.1 (corneal surface, 7.6 (0-50 µm, 5.4 (50-100 µm, 3.0 (100-150 µm, 1.6 (150-200 µm, and 1.5 (200-250 µm, when compared to the Young's modulus of the posterior 100 µm. The mean Young's modulus within the cross-linked zone was 20 ± 8 kPa (2.9-fold stiffening, while it was 11 ± 4 kPa (1.7-fold stiffening for the entire stroma. Both values were significantly distinct from the mean Young's modulus obtained from the posterior 100 µm of the cross-linked corneas and from the contralateral controls. In conclusion, we were able to specify the depth-dependent distribution of the stiffening effect elicited by standard collagen cross-linking in porcine corneas. Apart from determining the depth of the zone with effective corneal cross-linking, we also developed a method that allows for atomic force microscopy-based measurements of gradients of Young's modulus in soft

Method of Determining Reflections of Light

DEFF Research Database (Denmark)

2017-01-01

A method of filtering glints by processing an image of a user's cornea to obtain coordinates of desired glints from a configuration of light sources, comprising processing an image, in a first image space, of a user's cornea to determine coordinates of respective multiple positions of glints...

The effect of radiation and cystamine on the ability of the eye to induce the cornea in the intact skin

International Nuclear Information System (INIS)

Popov, D.V.; Starodubov, S.M.

1975-01-01

Common frog tadpoles (with and without cystamine protection) were subjected to whole-body irradiation (700 R) and skin transplanted from the back of donors to the site of the outer cornea of the right eye of the recipients. Secondary cornea induction in non-irradiated skin transplanted to the eye was then studied. It was found that a dose of 700 R completely suppresses the induction capacity of the eye, while cystamine protects it to 47.8%. It was also shown that the irradiation of tadpoles with X-rays slows down their general development, but that, with cystamine protection, their development rate remains normal. (V.A.P.)

Xanthelasma Palpebrarum with Arcus Cornea: A Clinical and Biochemical Study.

Science.gov (United States)

Nair, Pragya Ashok; Patel, Chaitali R; Ganjiwale, Jaishree D; Diwan, Nilofar Gulamsha; Jivani, Nidhi Bhimjibhai

2016-01-01

Xanthelasma palpebrarum (XP) is characterized by sharply demarcated yellowish flat plaques on upper and lower eyelids. It is commonly seen in women with a peak incidence at 30-50 years. It is also considered as the cutaneous marker of underlying atherosclerosis along with the disturbed lipid metabolism. XP and corneal arcus are associated with increased levels of serum cholesterol and low-density lipoprotein (LDL) cholesterol. To study the clinical pattern of XP, its relationship with lipid profile and association with arcus cornea. This study was conducted at Department of Dermatology and Opthalmology, between August 2013 and January 2015. Patients with clinical diagnosis of XP who visited skin outpatient department and willing to undergo lipid profile test and eye examination were included in the study. Data regarding demographics, clinical findings, family history, and past history were noted along with the lipid profile details. Data of age-matched healthy controls were taken for comparison. The clinical profile of the participants was presented using frequency and proportions. Gender wise analysis comparing the lipid profile in cases with XP and without XP was done using independent sample t-test. Total 49 patients of XP, 81.6% were females. Maximum, 35% patients were among 50-60 years of age and 69.4% were homemakers by occupation. The average lipid values were-cholesterol 210.57 mg%, triglyceride 123.06 mg%. LDL 142.79 mg% and VLDL 30.95 mg% among patients of XP. Arcus cornea was found in 20% cases of XP. Patients of XP requires proper investigation at the onset and regular follow-up thereafter for any altered lipid profile and early diagnosis of coronary artery disease.

Topical timolol with and without benzalkonium chloride: epithelial permeability and autofluorescence of the cornea in glaucoma.

Science.gov (United States)

de Jong, C; Stolwijk, T; Kuppens, E; de Keizer, R; van Best, J

1994-04-01

Epithelial permeability and autofluorescence of the cornea were determined by fluorophotometry in 21 patients with open-angle glaucoma or ocular hypertension using timolol medication with the preservative benzalkonium chloride (BAC) and 2 weeks after changing to timolol medication without BAC. The investigation was performed to determine whether removal of BAC would reduce toxic effects on the cornea and complaints of sensations of burning or dry eye. Corneal epithelial permeability decreased significantly after changing medication (mean decrease per patient 27%, P = 0.025). Corneal autofluorescence increased significantly after changing medication suggesting an alteration in corneal metabolism (mean increase per patient 6%, P = 0.003). Timolol without BAC was found to be as effective as timolol with BAC in reducing intraocular pressure (P = 0.4). Removal of BAC from timolol resulted in an improvement of corneal epithelial barrier function and in a reduction of complaints. The improvement was found to be proportional to the duration of the preceding BAC-containing therapy.

Femtosecond lasers for microsurgery of cornea

International Nuclear Information System (INIS)

Vartapetov, Sergei K; Khudyakov, D V; Lapshin, Konstantin E; Obidin, Aleksei Z; Shcherbakov, Ivan A

2012-01-01

The review of femtosecond laser installations for medical applications is given and a new femtosecond ophthalmologic system for creation of a flap of corneal tissue during the LASIK operation is described. An all-fibre femtosecond laser emitting ∼400-fs pulses at 1067 nm is used. The pulse repetition rate can vary from 200 kHz up to 1 MHz. The output energy of the femtosecond system does not exceed 1 μJ. A specially developed objective with small spherical and chromatic aberrations is applied to focus laser radiation to an area of an eye cornea. The size of the focusing spot does not exceed 3 μm. To process the required area, scanning by a laser beam is applied with a speed no less than 5 m s -1 . At a stage of preliminary tests of the system, the Κ8 glass, organic PMMA glass and specially prepared agarose gels are used as a phantom of an eye. The femtosecond system is successfully clinically tested on a plenty of eyes of a pig and on several human eyes. The duration of the procedure of creation of a corneal flap does not exceed 20 s.

Femtosecond lasers for microsurgery of cornea

Energy Technology Data Exchange (ETDEWEB)

Vartapetov, Sergei K; Khudyakov, D V; Lapshin, Konstantin E; Obidin, Aleksei Z; Shcherbakov, Ivan A

2012-03-31

The review of femtosecond laser installations for medical applications is given and a new femtosecond ophthalmologic system for creation of a flap of corneal tissue during the LASIK operation is described. An all-fibre femtosecond laser emitting {approx}400-fs pulses at 1067 nm is used. The pulse repetition rate can vary from 200 kHz up to 1 MHz. The output energy of the femtosecond system does not exceed 1 {mu}J. A specially developed objective with small spherical and chromatic aberrations is applied to focus laser radiation to an area of an eye cornea. The size of the focusing spot does not exceed 3 {mu}m. To process the required area, scanning by a laser beam is applied with a speed no less than 5 m s{sup -1}. At a stage of preliminary tests of the system, the {Kappa}8 glass, organic PMMA glass and specially prepared agarose gels are used as a phantom of an eye. The femtosecond system is successfully clinically tested on a plenty of eyes of a pig and on several human eyes. The duration of the procedure of creation of a corneal flap does not exceed 20 s.

Application of difference filter to Feynman-α analysis

International Nuclear Information System (INIS)

Mouri, Tomoaki; Ohtani, Nobuo

1997-11-01

The Feynman-α method has been developed for monitoring sub-criticality in nuclear fuel facilities. It is difficult to apply the Feynman-α method which estimates statistical variation of the number of neutron counts per unit time, to the system in transient condition such that the averaged neutron flux varies with time. In the application of Feynman-α method to such system, it is suggested to remove the averaged variation of neutron flux from neutron count data by the use of the difference filter. In this study, we applied the difference filter to reactor noise data at sub-criticality near to criticality, where the prompt decay constant was difficult to estimate due to the large effect of delayed neutron. With the difference filter, accurate prompt decay constants for effective multiplication factors from 0.999 to 0.994 were obtained by Feynman-α method. It was cleared that the difference filter is effective to estimate accurate prompt decay constant, so that there is the prospect to be able to apply Feynman-α method having the difference filter to the system in the transient condition. (author)

Marginalized particle filter for spacecraft attitude estimation from vector measurements

Institute of Scientific and Technical Information of China (English)

Yaqiu LIU; Xueyuan JIANG; Guangfu MA

2007-01-01

An algorithm based on the marginalized particle filters(MPF)is given in details in this paper to solve the spacecraft attitude estimation problem:attitude and gyro bias estimation using the biased gyro and vector observations.In this algorithm,by marginalizing out the state appearing linearly in the spacecraft model,the Kalman filter is associated with each particle in order to reduce the size of the state space and computational burden.The distribution of attitude vector is approximated by a set of particles and estimated using particle filter,while the estimation of gyro bias is obtained for each one of the attitude particles by applying the Kalman filter.The efficiency of this modified MPF estimator is verified through numerical simulation of a fully actuated rigid body.For comparison,unscented Kalman filter(UKF)is also used to gauge the performance of MPF.The results presented in this paper clearly demonstrate that the MPF is superior to UKF in coping with the nonlinear model.

An experimental study on the characteristics of electromagnetic filter

International Nuclear Information System (INIS)

Lee, Geum Yong; Lim, Seung Cheol; Lee, Kun Jai

1993-01-01

The electromagnetic filter has been recognized as a technological replacement for the conventional filtration systems of the nuclear power plant coolant. But, as of now there are neither clear understandings of the phenomena occurring in the electromagnetic filter nor the general theoretical analyses. These facts make the application of the electromagnetic filter to the real systems a little risky, and therfore it has not been commercialized although it shows excellent performances in such situations as the plant abnormality, where the conventional filters usually fail. This experimental study of the low power electromagnetic filter aims at the clarification of the general characteristics under varying operational parameters. Since the detailed characteristics may differ from one electromagnetic filter to another, they are considered secondary. The impurities applied are the highly magnetic magnetite (Fe 3 O 4 ) and the diamagnetic cuprous oxide (Cu 2 O). The empirical equations are derived from the experimental data by the regressional analyses. They are classified of three types : Efficiencies vs. Time, Efficiencies vs. Load, and Load vs. Time. The characteristics of the electromagnetic filter observed in this experiment agreed well with other related works in many aspects. Especially in this study, some assumptions and discussions including the physical deposition are combined for the explanations of the filter characteristics found in our and other experimental works. (Author)

77 FR 21277 - Customer Clearing Documentation, Timing of Acceptance for Clearing, and Clearing Member Risk...

Science.gov (United States)

2012-04-09

..., 23, 37, et al. Customer Clearing Documentation, Timing of Acceptance for Clearing, and Clearing..., 38, and 39 RIN 3038-0092, -0094 Customer Clearing Documentation, Timing of Acceptance for Clearing... implement new statutory provisions enacted by Title VII of the Dodd-Frank Wall Street Reform and Consumer...

Establishment of a new in vitro test method for evaluation of eye irritancy using a reconstructed human corneal epithelial model, LabCyte CORNEA-MODEL.

Science.gov (United States)

Katoh, Masakazu; Hamajima, Fumiyasu; Ogasawara, Takahiro; Hata, Ken-ichiro

2013-12-01

Finding in vitro eye irritation testing alternatives to animal testing such as the Draize eye test, which uses rabbits, is essential from the standpoint of animal welfare. It has been developed a reconstructed human corneal epithelial model, the LabCyte CORNEA-MODEL, which has a representative corneal epithelium-like structure. Protocol optimization (pre-validation study) was examined in order to establish a new alternative method for eye irritancy evaluation with this model. From the results of the optimization experiments, the application periods for chemicals were set at 1min for liquid chemicals or 24h for solid chemicals, and the post-exposure incubation periods were set at 24h for liquids or zero for solids. If the viability was less than 50%, the chemical was judged to be an eye irritant. Sixty-one chemicals were applied in the optimized protocol using the LabCyte CORNEA-MODEL and these results were evaluated in correlation with in vivo results. The predictions of the optimized LabCyte CORNEA-MODEL eye irritation test methods were highly correlated with in vivo eye irritation (sensitivity 100%, specificity 80.0%, and accuracy 91.8%). These results suggest that the LabCyte CORNEA-MODEL eye irritation test could be useful as an alternative method to the Draize eye test. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vaginose bacteriana e DNA de papilomavírus humano de alto risco oncogênico em mulheres submetidas a conização com alça diatérmica para tratamento de neoplasia intra-epitelial cervical de alto grau Bacterial vaginosis and high-risk HPV-DNA in women submitted to diathermic conization for the treatment of high-grade cervical intra-epithelial neoplasia

Directory of Open Access Journals (Sweden)

Michelle Garcia Discacciati

2004-10-01

ção às mulheres sem VB, ainda que estatisticamente não significativa. Esta associação não foi relacionada à presença do DNA de HPV de alto risco.PURPOSE: to analyze the association between bacterial vaginosis (BV, high-risk HPV DNA, and Pap smear abnormalities in women submitted to diathermic conization for the treatment of high-grade cervical intraepithelial neoplasia (CIN 2 or 3. METHODS: a descriptive clinical study with 81 women submitted to diathermic conization for the treatment of CIN 2 or 3. Initial Pap smear was performed by the time of the biopsy and was also used to verify the presence of BV. Prior to conization, samples for the detection of high-risk HPV DNA through hybrid capture II (HC II were collected. A control visit was scheduled for four months after the conization to repeat these tests. Twenty-seven women were found to have BV and 54 were not. Statistical analysis comprised odds ratios (OR to assess the correlations between BV and HPV detection before and after diathermic conization and cytological abnormalities. All analyses were performed with a 95% confidence interval (95% CI. RESULTS: high-risk HPV DNA detection before conization was identical in both groups (89%. After conization, HPV DNA detection decreased to 26 and 18% in the groups with and without BV, respectively (OR=1.5; 95% CI 0.5 to 4.6. In addition, 41% of the women with BV and 20% without BV showed Pap smear abnormalities (OR=2.7; 95% CI 1.0 to 7.4. Regarding these 22 women with Pap smear abnormalities approximately four months after the diathermic conization, 83% of the BV group tested positive for HPV DNA compared with 50% in the group without BV (OR=5.0; IC 95% 0.5 a 52.9. CONCLUSION: women with BV presented more Pap smear abnormalities after conization when compared to the women without BV, although this was not statistically significant. This association was not related to high-risk HPV DNA.

Xanthelasma palpebrarum with arcus cornea: A clinical and biochemical study

Directory of Open Access Journals (Sweden)

Pragya Ashok Nair

2016-01-01

Full Text Available Background: Xanthelasma palpebrarum (XP is characterized by sharply demarcated yellowish flat plaques on upper and lower eyelids. It is commonly seen in women with a peak incidence at 30–50 years. It is also considered as the cutaneous marker of underlying atherosclerosis along with the disturbed lipid metabolism. XP and corneal arcus are associated with increased levels of serum cholesterol and low-density lipoprotein (LDL cholesterol. Aims and Objectives: To study the clinical pattern of XP, its relationship with lipid profile and association with arcus cornea. Materials and Methods: This study was conducted at Department of Dermatology and Opthalmology, between August 2013 and January 2015. Patients with clinical diagnosis of XP who visited skin outpatient department and willing to undergo lipid profile test and eye examination were included in the study. Data regarding demographics, clinical findings, family history, and past history were noted along with the lipid profile details. Data of age-matched healthy controls were taken for comparison. The clinical profile of the participants was presented using frequency and proportions. Gender wise analysis comparing the lipid profile in cases with XP and without XP was done using independent sample t-test. Results: Total 49 patients of XP, 81.6% were females. Maximum, 35% patients were among 50–60 years of age and 69.4% were homemakers by occupation. The average lipid values were-cholesterol 210.57 mg%, triglyceride 123.06 mg%. LDL 142.79 mg% and VLDL 30.95 mg% among patients of XP. Arcus cornea was found in 20% cases of XP. Conclusions: Patients of XP requires proper investigation at the onset and regular follow-up thereafter for any altered lipid profile and early diagnosis of coronary artery disease.

Partial Denervation of Subbasal Axons Persists Following Debridement Wounds to the Mouse Cornea

Science.gov (United States)

Pajoohesh-Ganji, Ahdeah; Pal-Ghosh, Sonali; Tadvalkar, Gauri; Kyne, Briana M.; Saban, Daniel R.; Stepp, Mary Ann

2015-01-01

Although sensory reinnervation occurs after injury in the PNS, poor reinnervation in the elderly and those with diabetes often leads to pathology. Here we quantify subbasal axon density in the central and peripheral mouse cornea over time after three different types of injury. The mouse cornea is highly innervated with a dense array of subbasal nerves that form a spiral called the vortex at the corneal center or apex; these nerves are readily detected within flat mounted corneas. After anesthesia, corneal epithelial cells were removed using either a dulled blade or a rotating burr within an area demarcated centrally with a 1.5 mm trephine. A third wound type, superficial trephination, involved demarcating the area with the 1.5 mm trephine but not removing cells. By 7d after superficial trephination, subbasal axon density returns to control levels; by 28d the vortex reforms. Although axon density is similar to control 14d after dulled blade and rotating burr wounding, defects in axon morphology at the corneal apex remain. After 14d, axons retract from the center leaving the subbasal axon density reduced by 37.2% and 36.8% at 28d after dulled blade and rotating burr wounding, respectively, compared to control. Assessment of inflammation using flow cytometry shows that persistent inflammation is not a factor in the incomplete reinnervation. Expression of mRNAs encoding 22 regeneration associated genes (RAGs) involved in axon targeting assessed by QPCR reveals that netrin-1 and ephrin signaling are altered after wounding. Subpopulations of corneal epithelial basal cells at the corneal apex stop expressing ki67 as early as 7d after injury and by 14d and 28d after wounding, many of these basal cells undergo apoptosis and die. While subbasal axons are restored to their normal density and morphology after superficial trephination, subbasal axon recovery is partial after debridement wounds. The increase in corneal epithelial basal cell apoptosis at the apex observed at 14d

Oxidative Stress to the Cornea, Changes in Corneal Optical Properties, and Advances in Treatment of Corneal Oxidative Injuries

Directory of Open Access Journals (Sweden)

Cestmir Cejka

2015-01-01

Full Text Available Oxidative stress is involved in many ocular diseases and injuries. The imbalance between oxidants and antioxidants in favour of oxidants (oxidative stress leads to the damage and may be highly involved in ocular aging processes. The anterior eye segment and mainly the cornea are directly exposed to noxae of external environment, such as air pollution, radiation, cigarette smoke, vapors or gases from household cleaning products, chemical burns from splashes of industrial chemicals, and danger from potential oxidative damage evoked by them. Oxidative stress may initiate or develop ocular injury resulting in decreased visual acuity or even vision loss. The role of oxidative stress in the pathogenesis of ocular diseases with particular attention to oxidative stress in the cornea and changes in corneal optical properties are discussed. Advances in the treatment of corneal oxidative injuries or diseases are shown.

Penetration of 45Ca in rabbit cornea following the introduction of air in the anterior chamber and its paracenthesis and following experimental intraocular hypertension

International Nuclear Information System (INIS)

Votockova, J.; Obenberger, J.; Babicky, A.

1977-01-01

In one group of Chinchilla rabbits the aqueous humor was withdrawn and the anterior chamber was refilled with air; in a second group only simple paracenthesis and withdrawal were performed; in a third group of animals experimental intraocular hypertension was produced by means of a subconjunctival injection of hypertonic sodium chloride. Immediately after these operations, a solution of 45 CaCl 2 was intravenously injected, and the rabbits were sacrificed after an interval of 30 min or 120 min. The corneas were excised and the radioactivity in central parts (trephined discs of 8 mm in diameter) and in remaining peripheral parts was determined. In all groups the corneal radioactivity in operated eyes exceeded the values found in the contralateral corneas of not operated eyes, radioactivity in these eyes being equal to the radioactivity found in the corneas of not operated rabbits in the control group. Various possible explanations of the increase of corneal radioactivity in operated eyes are briefly discussed. (author)

Effect of a pulsed magnetic field on permeability of the cornea and sorption properties of the tissue structures and refractive media of the eye

International Nuclear Information System (INIS)

Skrinnik, A.V.

1986-01-01

The author attempts to obtain direct proof of increased permeability of the cornea and enhanced sorption properties of the tissue structures and refractive media of the eye under the influence of a pulsed magnetic field (MF). In the course of the investigation, the method of radioactive indication of two substances ( 35 S-streptomycin and 75 Se-methionine), widely used in opthalmologic practice, was used. The radioactivity of the working solution of the preparations was 300,000 cpm in 0.1 ml. Changes in the permeability of the cornea were assessed on the basis of changes in radioactivity of the aqueous humor. The concentration of 35 S-streptomycin in aqueous humor of the animals immediately after exposure to MF was significantly higher than in the control. Analysis of permeability of the cornea for 75 Se-methionine also showed increased penetration of radioactivity into the aqueous. The results are evidence of the greater penetrating power of 75 Se-methionine

Experience of Comamonas Acidovorans Keratitis with Delayed Onset and Treatment Response in Immunocompromised Cornea

OpenAIRE

Lee, Sang Mok; Kim, Mee Kum; Lee, Jae Lim; Wee, Won Ryang; Lee, Jin Hak

2008-01-01

Purpose To report 2 cases of Comamonas Acidovorans keratitis in immunocompromised cornea. Methods A complete review of the medical records of the two cases of Comamonas acidovorans keratitis. Results We found some similarities in clinical courses of two cases. Both of them showed development of keratitis during the management with corticosteroids, delayed onset, slow response to antibiotics, and relatively less affected corneal epithelium. Conclusions Comamonas Acidovorans is known as a less ...

Effect of biometric characteristics on biomechanical properties of the cornea in cataract patient.

Science.gov (United States)

Song, Xue-Fei; Langenbucher, Achim; Gatzioufas, Zisis; Seitz, Berthold; El-Husseiny, Moatasem

2016-01-01

To determine the impact of biometric characteristics on the biomechanical properties of the human cornea using the ocular response analyzer (ORA) and standard comprehensive ophthalmic examinations before and after standard phacoemulsification. This study comprised 54 eyes with cataract with significant lens opacification in stages I or II that underwent phacoemulsification (2.8 mm incision). Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) were measured by ORA preoperatively and at 1mo postoperatively. Biometric characteristics were derived from corneal topography [TMS-5, anterior equivalent (EQTMS) and cylindric (CYLTMS) power], corneal tomography [Casia, anterior and posterior equivalent (EQaCASIC, EQpCASIA) and cylindric (CYLaCASIA, CYLpCASIA) power], keratometry [IOLMaster, anterior equivalent (EQIOL) and cylindric (CYLIOL) power] and autorefractor [anterior equivalent (EQAR)]. Results from ORA were analyzed and correlated with those from all other examinations taken at the same time point. Preoperatively, CH correlated with EQpCASIA and CYLpCASIA only (P=0.001, P=0.002). Postoperatively, IOPg and IOPcc correlated with all equivalent powers (EQTMS, EQIOL, EQAR, EQaCASIA and EQpCASIA) (P=0.001, P=0.007, P=0.001, P=0.015, P=0.03 for IOPg and PBiometric characteristics may significantly affect biomechanical properties of the cornea in terms of CH, IOPcc and IOPg before, but even more after cataract surgery.

Stability Study of Sunscreens with Free and Encapsulated UV Filters Contained in Plastic Packaging.

Science.gov (United States)

Briasco, Benedetta; Capra, Priscilla; Mannucci, Barbara; Perugini, Paola

2017-05-31

Sunscreens play a fundamental role in skin cancer prevention and in protection against photo-aging. UV filters are often photo-unstable, especially in relation to their vehicles and, being lipophilic substances, they are able to interact with plastic packaging. Finally, UV filter stability can be significantly affected by the routine use of the product at high temperatures. This work aims to study the stability of sunscreen formulations in polyethylene packaging. Butyl methoxydibenzoylmethane and octocrylene, both in a free form and as encapsulated filters were chosen as UV filters. Stability evaluations were performed both in the packaging and on the formulations. Moreover, a further two non-destructive techniques, near-infrared (NIR) spectroscopy and a multiple light scattering technique, were also used to evaluate the stability of the formulation. Results demonstrated clearly that all of the pack underwent significant changes in its elastic/plastic behavior and in external color after solar irradiation. From the evaluation of the extractable profile of untreated and treated packaging material an absorption of 2-phenoxyethanol and octocrylene were shown. In conclusion, the results highlighted clearly that a reduction of the UV filter in the formulation packed in high-density polyethylene/low-density polyethylene (HDPE/LDPE) material can occur over time, reducing the protective effect of the product when applied to the skin.

Ab Interno Trabeculectomy With the Trabectome as a Valuable Therapeutic Option for Failed Filtering Blebs.

Science.gov (United States)

Wecker, Thomas; Neuburger, Matthias; Bryniok, Laura; Bruder, Kathrin; Luebke, Jan; Anton, Alexandra; Jordan, Jens F

2016-09-01

Uncontrolled intraocular pressure (IOP) after glaucoma filtration surgery is a challenging problem in the management of glaucoma patients. The Trabectome is a device for selective electroablation of the trabecular meshwork through a clear cornea incision without affecting the conjunctiva. Minimally invasive glaucoma surgery using the Trabectome is safe and effective as primary glaucoma surgery. Here we investigate the results of ab interno trabeculectomy with the Trabectome for IOP control in patients with a failed filtering bleb. A total of 60 eyes of 60 consecutive patients with primary open-angle glaucoma (POAG) or pseudoexfoliative glaucoma (PXG) were enrolled in this single center observational study. Trabectome surgery was performed alone or in combination with phacoemulsification by 2 experienced surgeons. IOP readings and number of IOP lowering medication as primary outcome parameters were taken by an independent examiner. Intraoperative and postoperative medication were recorded systematically. Mean IOP before surgery was 24.5±3.5 mm Hg and decreased to 15.7±3.4 (-36%) after mean follow-up of 415 days. The number of necessary IOP lowering medication dropped from 2.1±1.3 to 1.8±1.2 (14% reduction from baseline). A total of 25% (n=15) of cases reported here needed additional surgery after 517 days (range: 6 to 1563 d). No major complications were observed. After mean follow-up, we found a qualified success rate for PXG of 87% and 50% for POAG as revealed by the Kaplan-Meier analysis according to the definitions for success in advanced glaucoma cases according to the World Glaucoma Association (40% reduction from baseline IOP and maximum IOP of 15 mm Hg). Trabectome surgery for uncontrolled IOP after trabeculectomy is safe and effective especially in PXG patients. Given the demanding subgroup of patients studied here, it is not surprising that success rates are lower compared with previous studies investigating the Trabectome for primary glaucoma surgery

Corneal NF-kappaB activity is necessary for the retention of transparency in the cornea of UV-B-exposed transgenic reporter mice.

Science.gov (United States)

Alexander, George; Carlsen, Harald; Blomhoff, Rune

2006-04-01

To determine the dynamics of Nuclear Factor-kappaB (NF-kappaB) in murine corneal pathology and the role of NF-kappaB in maintaining corneal clarity after ultraviolet B radiation insult, transgenic mice containing NF-kappaB-luciferase reporter were exposed to LPS (bacterial lipopolysaccharide), TNF-alpha (Tumor Necrosis Factor-alpha) or 4 kJ m(-2) UV-B radiation. NF-kappaB decoy oligonucleotides were also administered in some of the UV-B experiments. Following various exposure times, the mice were sacrificed and whole eyes or corneal tissues were obtained. Whole eyes were examined for scattering using a point-source optical imaging technique. Tissue homogenates were examined for luciferase activity using a luminometer. TNF-alpha and LPS-injected NF-kappaB-luciferase transgenic mice demonstrated 3-10-fold increases in cornea NF-kappaB with peak activities at 4 and 6 hr post-injection, respectively. Mice exposed to 4 kJ m(-2) UV-B exhibited a 3-fold increase in NF-kappaB activity 4 hr post-exposure. The administration of NF-kappaB-decoy oligonucleotides to mice had the effect of reducing UV-B-induced NF-kappaB activity in the cornea and significantly increasing the amount of light scattering in UV-B exposed corneas 7 days post-UV-B exposure when compared to sham injected mice. These results indicate that NF-kappaB is activated in cornea in pathologies that involves increased plasma levels of LPS and TNF-alpha, as well as direct UV-B exposure, and suggest that NF-kappaB activation play an essential part in the corneal healing process.

Case report: a novel KERA mutation associated with cornea plana and its predicted effect on protein function

DEFF Research Database (Denmark)

Roos, Laura; Bertelsen, Birgitte; Harris, Pernille

2015-01-01

of the keratocan gene (KERA) on chromosome 12q22. To date, only nine different disease-associated KERA mutations, including four missense mutations, have been described. Case presentation: In this report, we present clinical data from a Turkish family with autosomal recessive cornea plana. In some of the affected...

Thermal lens measurements in the cornea.

Science.gov (United States)

Venkatesh, S; Guthrie, S; Cruickshank, F R; Bailey, R T; Foulds, W S; Lee, W R

1985-02-01

Q-switched pulses from a neodymium/YAG (yttrium-aluminium-garnet) laser were passed through corneal discs taken from the enucleated eyes of three baboons and four rabbits. The time course of heat dissipation following absorption of laser energy by the tissue was studied with the use of a second continuous wave laser beam acting as a probe. It was found that the absorption of each neodymium/YAG pulse created a transient divergent lens within the cornea as theoretical considerations predicted. The relaxation time that characterised the decay of this thermal lens for a 1/e laser beam diameter of 2.0 mm was found to be 2.3 +/- 0.1 s (mean +/- standard error for 12 separate groups of measurements). Our results show that Q-switched laser pulses passing through apparently unaffected transparent tissues can induce thermal lens effects which persist for several seconds. The optical transfer of each pulse in a stream will be identical only if enough time is left between pulses for the tissues to return to their initial state. Therefore, when such laser pulses sharply focused to perform high precision intraocular surgery are used, thermal lensing in the transparent ocular media must limit the rate at which pulses can be usefully delivered.

Optimization of Butterworth filter for brain SPECT imaging

International Nuclear Information System (INIS)

Minoshima, Satoshi; Maruno, Hirotaka; Yui, Nobuharu

1993-01-01

A method has been described to optimize the cutoff frequency of the Butterworth filter for brain SPECT imaging. Since a computer simulation study has demonstrated that separation between an object signal and the random noise in projection images in a spatial-frequency domain is influenced by the total number of counts, the cutoff frequency of the Butterworth filter should be optimized for individual subjects according to total counts in a study. To reveal the relationship between the optimal cutoff frequencies and total counts in brain SPECT study, we used a normal volunteer and 99m Tc hexamethyl-propyleneamine oxime (HMPAO) to obtain projection sets with different total counts. High quality images were created from a projection set with an acquisition time of 300-seconds per projection. The filter was optimized by calculating mean square errors from high quality images visually inspecting filtered reconstructed images. Dependence between total counts and optimal cutoff frequencies was clearly demonstrated in a nomogram. Using this nomogram, the optimal cutoff frequency for each study can be estimated from total counts, maximizing visual image quality. The results suggest that the cutoff frequency of Butterworth filter should be determined by referring to total counts in each study. (author)

Sensory Pollution from Bag Filters, Carbon Filters and Combinations

DEFF Research Database (Denmark)

Bekö, Gabriel; Clausen, Geo; Weschler, Charles J.

2008-01-01

by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter...... that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC...

Clinical characteristics of keratoconus patients in Malaysia: a review from a cornea specialist centre

OpenAIRE

Mohd-Ali, Bariah; Abdu, Mustafa; Yaw, Choong Yean; Mohidin, Norhani

2012-01-01

Purpose: To evaluate the demographic profile, refraction, visual acuity (VA), corneal curvature (K) and severity of keratoconus (KC) patients from a cornea specialist centre in Malaysia. This may improve the management of KC patients in this country. Methods: Records of 13,000 patients were reviewed. The patients were categorized into 4 age groups: (Gp 1: 42 years). Refraction and VA were determined using subjective refraction and Snellen chart. Corneal curvature was measured using Orbscan...

Respiratory-Induced Haemodynamic Changes: A Contributing Factor to IVC Filter Penetration

International Nuclear Information System (INIS)

Laborda, Alicia; Kuo, William T.; Ioakeim, Ignatios; De Blas, Ignacio; Malvè, Mauro; Lahuerta, Celia; De Gregorio, Miguel A.

2015-01-01

PurposeThe purpose of the study is to evaluate the influence of respiratory-induced vena caval hemodynamic changes on filter migration/penetration.Materials and MethodsAfter placement of either a Gunther Tulip or Celect IVC filter, 101 consecutive patients scheduled for filter retrieval were prospectively enrolled in this study. Pre-retrieval CT scans were used to assess filter complications and to calculate cross-sectional area in three locations: at level of filter strut fixation, 3 cm above and 3 cm below. A 3D finite element simulation was constructed on these data and direct IVC pressure was recorded during filter retrieval. Cross-sectional areas and pressures of the vena cava were measured during neutral breathing and in Valsalva maneuver and identified filter complications were recorded. A statistical analysis of these variables was then performed.ResultsDuring Valsalva maneuvers, a 60 % decrease of the IVC cross-sectional area and a fivefold increase in the IVC pressure were identified (p < 0.001). There was a statistically significant difference in the reduction of the cross-sectional area at the filter strut level (p < 0.001) in patient with filter penetration. Difficulty in filter retrieval was higher in penetrated or tilted filters (p < 0.001; p = 0.005). 3D computational models showed significant IVC deformation around the filter during Valsalva maneuver.ConclusionCaval morphology and hemodynamics are clearly affected by Valsalva maneuvers. A physiological reduction of IVC cross-sectional area is associated with higher risk of filter penetration, despite short dwell times. Physiologic data should be used to improve future filter designs to remain safely implanted over longer dwell times

Respiratory-Induced Haemodynamic Changes: A Contributing Factor to IVC Filter Penetration

Energy Technology Data Exchange (ETDEWEB)

Laborda, Alicia, E-mail: alaborda@unizar.es [Universidad de Zaragoza, Minimally Invasive Techniques Research Group (GITMI) (Spain); Kuo, William T., E-mail: wkuo@stanford.edu [Stanford University Medical Center, Division of Vascular and Interventional Radiology (United States); Ioakeim, Ignatios, E-mail: ignacio.ioakim@hotmail.es [Universidad de Zaragoza, Minimally Invasive Techniques Research Group (GITMI) (Spain); De Blas, Ignacio, E-mail: deblas@unizar.es [Universidad de Zaragoza, Unit of Infectious Diseases and Epidemiology, Department of Animal Pathology (Spain); Malvè, Mauro, E-mail: mauro.malve@unavarra.es [Universidad Pública de Navarra, Department of Mechanical, Energy and Materials Engineering (Spain); Lahuerta, Celia, E-mail: celialahuerta@gmail.com; De Gregorio, Miguel A., E-mail: mgregori@unizar.es [Universidad de Zaragoza, Minimally Invasive Techniques Research Group (GITMI) (Spain)

2015-10-15

PurposeThe purpose of the study is to evaluate the influence of respiratory-induced vena caval hemodynamic changes on filter migration/penetration.Materials and MethodsAfter placement of either a Gunther Tulip or Celect IVC filter, 101 consecutive patients scheduled for filter retrieval were prospectively enrolled in this study. Pre-retrieval CT scans were used to assess filter complications and to calculate cross-sectional area in three locations: at level of filter strut fixation, 3 cm above and 3 cm below. A 3D finite element simulation was constructed on these data and direct IVC pressure was recorded during filter retrieval. Cross-sectional areas and pressures of the vena cava were measured during neutral breathing and in Valsalva maneuver and identified filter complications were recorded. A statistical analysis of these variables was then performed.ResultsDuring Valsalva maneuvers, a 60 % decrease of the IVC cross-sectional area and a fivefold increase in the IVC pressure were identified (p < 0.001). There was a statistically significant difference in the reduction of the cross-sectional area at the filter strut level (p < 0.001) in patient with filter penetration. Difficulty in filter retrieval was higher in penetrated or tilted filters (p < 0.001; p = 0.005). 3D computational models showed significant IVC deformation around the filter during Valsalva maneuver.ConclusionCaval morphology and hemodynamics are clearly affected by Valsalva maneuvers. A physiological reduction of IVC cross-sectional area is associated with higher risk of filter penetration, despite short dwell times. Physiologic data should be used to improve future filter designs to remain safely implanted over longer dwell times.

Partial denervation of sub-basal axons persists following debridement wounds to the mouse cornea.

Science.gov (United States)

Pajoohesh-Ganji, Ahdeah; Pal-Ghosh, Sonali; Tadvalkar, Gauri; Kyne, Briana M; Saban, Daniel R; Stepp, Mary Ann

2015-11-01

Although sensory reinnervation occurs after injury in the peripheral nervous system, poor reinnervation in the elderly and those with diabetes often leads to pathology. Here we quantify sub-basal axon density in the central and peripheral mouse cornea over time after three different types of injury. The mouse cornea is highly innervated with a dense array of sub-basal nerves that form a spiral called the vortex at the corneal center or apex; these nerves are readily detected within flat mounted corneas. After anesthesia, corneal epithelial cells were removed using either a dulled blade or a rotating burr within an area demarcated centrally with a 1.5 mm trephine. A third wound type, superficial trephination, involved demarcating the area with the 1.5 mm trephine but not removing cells. By 7 days after superficial trephination, sub-basal axon density returns to control levels; by 28 days the vortex reforms. Although axon density is similar to control 14 days after dulled blade and rotating burr wounding, defects in axon morphology at the corneal apex remain. After 14 days, axons retract from the center leaving the sub-basal axon density reduced by 37.2 and 36.8% at 28 days after dulled blade and rotating burr wounding, respectively, compared with control. Assessment of inflammation using flow cytometry shows that persistent inflammation is not a factor in the incomplete reinnervation. Expression of mRNAs encoding 22 regeneration-associated genes involved in axon targeting assessed by QPCR reveals that netrin-1 and ephrin signaling are altered after wounding. Subpopulations of corneal epithelial basal cells at the corneal apex stop expressing ki67 as early as 7 days after injury and by 14 and 28 days after wounding, many of these basal cells undergo apoptosis and die. Although sub-basal axons are restored to their normal density and morphology after superficial trephination, sub-basal axon recovery is partial after debridement wounds. The increase in corneal

Hiding objects and creating illusions above a carpet filter using a Fourier optics approach.

Science.gov (United States)

Wu, Kedi; Wang, Guo Ping

2010-09-13

Invisibility carpet cloaks are usually used to hide an object beneath carpet. In this paper we propose and demonstrate a carpet filter to hide objects and create illusions above the filter by using a Fourier optics method. Instead of using transformation optics, we get electromagnetic parameters of the filter by optical transfer functions, which play the role of modulating the propagation of the scattering angular spectrum directly from an object above the filter. By further adding a functional layer onto the filter, we can even camouflage the object so that it appears to be a different object. The analytical results are confirmed by numerical simulations. Our method is completely different from the current coordinate transfer method and may provide another point of view to more clearly understand the mechanism of invisibility cloaks.

Filter arrays

Science.gov (United States)

Page, Ralph H.; Doty, Patrick F.

2017-08-01

The various technologies presented herein relate to a tiled filter array that can be used in connection with performance of spatial sampling of optical signals. The filter array comprises filter tiles, wherein a first plurality of filter tiles are formed from a first material, the first material being configured such that only photons having wavelengths in a first wavelength band pass therethrough. A second plurality of filter tiles is formed from a second material, the second material being configured such that only photons having wavelengths in a second wavelength band pass therethrough. The first plurality of filter tiles and the second plurality of filter tiles can be interspersed to form the filter array comprising an alternating arrangement of first filter tiles and second filter tiles.

Altered corneal stromal matrix organization is associated with mucopolysaccharidosis I, III and VI.

Science.gov (United States)

Alroy, J; Haskins, M; Birk, D E

1999-05-01

The presence of cloudy corneas is a prominent feature of mucopolysaccharidosis (MPS) types I and VI, but not MPS IIIA or IIIB. The cause of corneal cloudiness in MPS I and VI is speculative. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The purpose of this study was to compare the structural organization of the stromal extracellular matrix of normal corneas with that of MPS corneas. The size and arrangement of collagen fibrils in cloudy corneas from patients with MPS I were examined. The alterations observed were an increased mean fibril diameter with a broader distribution in the MPS corneas. The MPS I corneas also had altered fibril spacing and more irregular packing compared with normal control corneas. The clear corneas of patients with MPS IIIA and IIIB also showed increases in mean fibril diameter and fibril spacing. However, there was less variation indicating more regularity than seen in MPS I. In addition, corneas from cat models of certain MPS were compared to the human corneas. Cats with MPS I and VI, as well as normal control cats, were examined. Structural alterations comparable to those seen in human MPS corneas were seen in MPS I and VI cats relative to normal clear corneas. The findings suggest that cloudy corneas in MPS I and VI are in part a consequence of structural alterations in the corneal stroma, including abnormal spacing, size, and arrangement of collagen fibrils. Copyright 1999 Academic Press.

Behaviour of glutathione in the cornea epithelium of cattle and rabbits under the influence of infrared radiation

International Nuclear Information System (INIS)

Scharsich, G.

1978-01-01

After creating a keratitis photoelectrica by means of a mercury/quartz analysis lamp, the concentration of GSH (glutathion, reduced) and GSSG (glutathion, oxidised) in the cornea epithelium of cattle and of rabbits at different times after irradiation was determined. The question of whether ultraviolet radiation considerably influences the GSH/GSSG quotient before the keratitis photoelectrica is fully formed morphologically, could be answered as follows: There is no considerable change in the GSH/GSSG quotient during the first 7-10 hours after the irradiation. Then, when there is, also morphologically, a keratitis photoelectrica, the GSH/GSSG quotient is doubled. The linkage of the GSH/GSSG system and hexosephosphatshunt via the NADP/NADPH system leads us to the conclusion that irradiation does not cause any direct changes in the GSH/GSSG system. Only when the cornea epithelium visably disintegrates an increased reduction of the glutathion occurs, like in several other damaging influences. Thus the found increase of the GSH/GSSG quotient 7-10 hours after ultraviolet irradiation might be unspecific. (orig./AJ) [de

The effects of oral and topical corticosteroid in rabbit corneas.

Science.gov (United States)

Araki-Sasaki, Kaoru; Katsuta, Osamu; Mano, Hidetoshi; Nagano, Takashi; Nakamura, Masatsugu

2016-09-05

To determine the most effective route of administration of corticosteroids in the treatment of ocular surface disease, by characterizing the difference between oral prednisolone and topical dexamethasone administration using an animal model. Pharmacokinetic analyses determined the corticosteroid concentrations in the normal ocular tissues of rabbits after oral or topical administration of corticosteroids using LC-MS/MS. In wound healing analyses, the area of the epithelial defect created by keratectomy using a 6-mm trephine was calculated with an image analyzer using an orally or topically steroid-administrated animal model. The average size of basal epithelial cells, the frequency of mitotic basal epithelial cells, the number of squamous cells, and the number of hypertrophic stromal fibroblasts were determined in the enucleated corneal tissues after wound closure. By slit lamp examination, no remarkable differences were observed between orally and topically administered groups. Pharmacokinetic analyses showed that the distribution of dexamethasone after topical administration was superior to that after oral administration in the cornea. In contrast, both concentrations of corticosteroid applied topically and orally were similar with regards to AUCs (area under the concentration-time curve) in the conjunctiva. Although the healing rate was slower in the topical group, all corneas were almost healed within 96 h in the wound healing analysis. According to the histological analyses of epithelial cells, the average basal cell size was larger, the frequency of mitotic basal cells was greater, and the number of squamous epithelial cell layers was lower in the topically administered group although all of these differences were with no statistical significance. However, the number of hypertrophic stromal fibroblasts in the topically administered group was significantly lower than that in the orally administered group. There are different distributions and effects between

Social influence of a religious hero: the late Cardinal Stephen Kim Sou-hwan's effect on cornea donation and volunteerism.

Science.gov (United States)

Bae, Hyuhn-Suhck; Brown, William J; Kang, Seok

2011-01-01

This study examined the mediated influence of a celebrated religious hero in South Korea, Cardinal Stephen Kim, through two forms of involvement--parasocial interaction and identification--on intention toward cornea donation and volunteerism, and it investigated how the news media diffused of his death. A structural equation modeling analysis with a Web-based voluntary survey of more than 1,200 people in South Korea revealed a multistep social influence process, beginning with parasocial interaction with Cardinal Kim, leading to identification with him, which predicted intention toward cornea donation and volunteerism. Additional investigations found that news of Cardinal Kim's death diffused rapidly through media and interpersonal communication. Results of this study demonstrate that religious leaders who achieve a celebrity hero status can prompt public discussion of important issues rather quickly through extensive media coverage, enabling them to promote prosocial behavior and positively affect public health.

Energy-Filtered Tunnel Transistor: A New Device Concept Toward Extremely-Low Energy Consumption Electronics

Science.gov (United States)

2015-12-17

other provision of law , no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a...excellent agreement with experimental findings. The energy filtering has been applied to single-electron transport and clear Coulomb staircases and... Coulomb oscillations have been demonstrated at room temperature. A new architecture of energy-filtered cold electron transistors has been designed and

Microscopia confocal de la córnea en facoemulsificación Confocal microscopy of the cornea on phacoemulsification

Directory of Open Access Journals (Sweden)

Juan Raúl Hernández Silva

2011-12-01

Full Text Available Objetivo: Determinar los cambios estructurales de la córnea en la cirugía de catarata por facoemulsificación sin complicaciones. Métodos: Se realizó un estudio prospectivo de pacientes operados de catarata por facoemulsificación coaxial por la técnica de pre chop sin complicaciones. A estos se les realizó microscopia confocal de la córnea con el CONFOSCAN 4 (Nidek Technologies con el objetivo de 40x y adaptador Z-Ring. Se realizó el estudio en el preoperatorio y en el posoperatorio (a las 24 horas, después de una semana, de un mes y a los tres meses. Resultados: Se demostraron cambios estructurales en la córnea como células epiteliales con núcleos hiperreflectivos alargadas en ocasiones y áreas de hiperreflectividad anómala a las 24 horas del posoperatorio. Persistieron queratocitos activados y la disminución de la hiperreflectividad de la matriz extracelular que desapareció al mes. Conclusiones: Aunque por biomicroscopia no se observen alteraciones corneales en el posoperatorio de la cirugía de catarata por facoemulsificación, sí se pueden demostrar por microscopia confocal de la córnea. Estas variaciones no influyen en la recuperación visual óptima de los pacientes.Objective: To determine the structural changes in the cornea in the cataract surgery using phacoemulsification without complications. Methods: A prospective study of patients operated on from cataract using the coaxial phacoemulsification (Pre Chop technique without complications was carried out. These patients also underwent confocal microscopy of the cornea with Confoscan4 (Nidek Technologies with 40x target and Z - Ring adapter. The study was performed in the preoperative period and postoperative period for 24 hours, one week, one month and three months after surgery. Results: Structural changes were observed in the cornea such as epithelial cells with hypereflectivity nucleus, occasionally elongated, , areas of anomalous hypereflectivity 24 hours after

The filter of choice: filtration method preference among injecting drug users

Directory of Open Access Journals (Sweden)

Keijzer Lenneke

2011-08-01

Full Text Available Abstract Background Injection drug use syringe filters (IDUSF are designed to prevent several complications related to the injection of drugs. Due to their small pore size, their use can reduce the solution's insoluble particle content and thus diminish the prevalence of phlebitis, talcosis.... Their low drug retention discourages from filter reuse and sharing and can thus prevent viral and microbial infections. In France, drug users have access to sterile cotton filters for 15 years and to an IDUSF (the Sterifilt® for 5 years. This study was set up to explore the factors influencing filter preference amongst injecting drug users. Methods Quantitative and qualitative data were gathered through 241 questionnaires and the participation of 23 people in focus groups. Results Factors found to significantly influence filter preference were duration and frequency of injecting drug use, the type of drugs injected and subculture. Furthermore, IDU's rationale for the preference of one type of filter over others was explored. It was found that filter preference depends on perceived health benefits (reduced harms, prevention of vein damage, protection of injection sites, drug retention (low retention: better high, protective mechanism against the reuse of filters; high retention: filter reuse as a protective mechanism against withdrawal, technical and practical issues (filter clogging, ease of use, time needed to prepare an injection and believes (the conviction that a clear solution contains less active compound. Conclusion It was concluded that the factors influencing filter preference are in favour of change; a shift towards the use of more efficient filters can be made through increased availability, information and demonstrations.

Digital Simulation of a Hybrid Active Filter - An Active Filter in Series with a Shunt Passive Filter

OpenAIRE

Sitaram, Mahesh I; Padiyar, KR; Ramanarayanan, V

1998-01-01

Active filters have long been in use for the filtering of power system load harmonics. In this paper, the digital simulation results of a hybrid active power filter system for a rectifier load are presented. The active filter is used for filtering higher order harmonics as the dominant harmonics are filtered by the passive filter. This reduces the rating of the active filter significantly. The DC capacitor voltage of the active filter is controlled using a PI controller.

Age-related changes in superoxide dismutase, glutathione peroxidase, catalase and xanthine oxidoreductase/xanthine oxidase activities in the rabbit cornea

Czech Academy of Sciences Publication Activity Database

Čejková, Jitka; Vejražka, M.; Pláteník, J.; Štípek, S.

2004-01-01

Roč. 39, - (2004), s. 1537-1543 ISSN 0531-5565 R&D Projects: GA ČR GA304/03/0419 Institutional research plan: CEZ:AV0Z5039906; CEZ:AV0Z5008914 Keywords : aging * cornea Subject RIV: FF - HEENT, Dentistry Impact factor: 2.880, year: 2004

Filter assembly for metallic and intermetallic tube filters

Science.gov (United States)

Alvin, Mary Anne; Lippert, Thomas E.; Bruck, Gerald J.; Smeltzer, Eugene E.

2001-01-01

A filter assembly (60) for holding a filter element (28) within a hot gas cleanup system pressure vessel is provided, containing: a filter housing (62), said filter housing having a certain axial length and having a peripheral sidewall, said sidewall defining an interior chamber (66); a one piece, all metal, fail-safe/regenerator device (68) within the interior chamber (66) of the filter housing (62) and/or extending beyond the axial length of the filter housing, said device containing an outward extending radial flange (71) within the filter housing for seating an essential seal (70), the device also having heat transfer media (72) disposed inside and screens (80) for particulate removal; one compliant gasket (70) positioned next to and above the outward extending radial flange of the fail-safe/regenerator device; and a porous metallic corrosion resistant superalloy type filter element body welded at the bottom of the metal fail-safe/regenerator device.

Statistically-Efficient Filtering in Impulsive Environments: Weighted Myriad Filters

Directory of Open Access Journals (Sweden)

Juan G. Gonzalez

2002-01-01

Full Text Available Linear filtering theory has been largely motivated by the characteristics of Gaussian signals. In the same manner, the proposed Myriad Filtering methods are motivated by the need for a flexible filter class with high statistical efficiency in non-Gaussian impulsive environments that can appear in practice. Myriad filters have a solid theoretical basis, are inherently more powerful than median filters, and are very general, subsuming traditional linear FIR filters. The foundation of the proposed filtering algorithms lies in the definition of the myriad as a tunable estimator of location derived from the theory of robust statistics. We prove several fundamental properties of this estimator and show its optimality in practical impulsive models such as the α-stable and generalized-t. We then extend the myriad estimation framework to allow the use of weights. In the same way as linear FIR filters become a powerful generalization of the mean filter, filters based on running myriads reach all of their potential when a weighting scheme is utilized. We derive the “normal” equations for the optimal myriad filter, and introduce a suboptimal methodology for filter tuning and design. The strong potential of myriad filtering and estimation in impulsive environments is illustrated with several examples.

Filter material charging apparatus for filter assembly for radioactive contaminants

International Nuclear Information System (INIS)

Goldsmith, J.M.; O'Nan, A. Jr.

1977-01-01

A filter charging apparatus for a filter assembly is described. The filter assembly includes a housing with at least one filter bed therein and the filter charging apparatus for adding filter material to the filter assembly includes a tank with an opening therein, the tank opening being disposed in flow communication with opposed first and second conduit means, the first conduit means being in flow communication with the filter assembly housing and the second conduit means being in flow communication with a blower means. Upon activation of the blower means, the blower means pneumatically conveys the filter material from the tank to the filter housing

Medline Plus

Full Text Available ... structures in the eye enable it to translate light into recognizable images. Among these are the cornea, the lens, and the retina. Light first passes through the cornea, a clear dome- ...

Collaborative filtering recommendation model based on fuzzy clustering algorithm

Science.gov (United States)

Yang, Ye; Zhang, Yunhua

2018-05-01

As one of the most widely used algorithms in recommender systems, collaborative filtering algorithm faces two serious problems, which are the sparsity of data and poor recommendation effect in big data environment. In traditional clustering analysis, the object is strictly divided into several classes and the boundary of this division is very clear. However, for most objects in real life, there is no strict definition of their forms and attributes of their class. Concerning the problems above, this paper proposes to improve the traditional collaborative filtering model through the hybrid optimization of implicit semantic algorithm and fuzzy clustering algorithm, meanwhile, cooperating with collaborative filtering algorithm. In this paper, the fuzzy clustering algorithm is introduced to fuzzy clustering the information of project attribute, which makes the project belong to different project categories with different membership degrees, and increases the density of data, effectively reduces the sparsity of data, and solves the problem of low accuracy which is resulted from the inaccuracy of similarity calculation. Finally, this paper carries out empirical analysis on the MovieLens dataset, and compares it with the traditional user-based collaborative filtering algorithm. The proposed algorithm has greatly improved the recommendation accuracy.

Prevalence of spheroidal degeneration of cornea and its association with other eye diseases in tribes of Western Rajasthan

Directory of Open Access Journals (Sweden)

Amit Mohan

2017-01-01

Full Text Available Purpose: To determine the prevalence of spheroidal degeneration of cornea (SDC and its association with other eye diseases in the tribes of South-West Rajasthan. Methods: A total of 5012 patients were examined on slit lamp for the diagnosis of SDC. Diagnosis of SDC was made based on presence of amber granules in the superficial stroma of peripheral interpalpebral cornea with increasing opacification, coalescence and central spread or nodular and hazy surrounding stroma and divided in three stages. Results: The prevalence of SDC was 10.7%. Around 55% of the total of 535 cases examined were found to have Stage I followed by Stage II (32% and Stage III (13%. The prevalence is greatest in both men and women over 70 years of age. The severity of SDC is greater in men. SDC was significantly associated with pterygium and pseudocapsular exfoliation. Conclusion: Extreme temperature, low humidity, dust, high wind, and microtrauma caused by sand particles are the probable etiologies for higher prevalence of this kind of degeneration in this region.

Block matching 3D random noise filtering for absorption optical projection tomography

International Nuclear Information System (INIS)

Fumene Feruglio, P; Vinegoni, C; Weissleder, R; Gros, J; Sbarbati, A

2010-01-01

Absorption and emission optical projection tomography (OPT), alternatively referred to as optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT), are recently developed three-dimensional imaging techniques with value for developmental biology and ex vivo gene expression studies. The techniques' principles are similar to the ones used for x-ray computed tomography and are based on the approximation of negligible light scattering in optically cleared samples. The optical clearing is achieved by a chemical procedure which aims at substituting the cellular fluids within the sample with a cell membranes' index matching solution. Once cleared the sample presents very low scattering and is then illuminated with a light collimated beam whose intensity is captured in transillumination mode by a CCD camera. Different projection images of the sample are subsequently obtained over a 360 0 full rotation, and a standard backprojection algorithm can be used in a similar fashion as for x-ray tomography in order to obtain absorption maps. Because not all biological samples present significant absorption contrast, it is not always possible to obtain projections with a good signal-to-noise ratio, a condition necessary to achieve high-quality tomographic reconstructions. Such is the case for example, for early stage's embryos. In this work we demonstrate how, through the use of a random noise removal algorithm, the image quality of the reconstructions can be considerably improved even when the noise is strongly present in the acquired projections. Specifically, we implemented a block matching 3D (BM3D) filter applying it separately on each acquired transillumination projection before performing a complete three-dimensional tomographical reconstruction. To test the efficiency of the adopted filtering scheme, a phantom and a real biological sample were processed. In both cases, the BM3D filter led to a signal-to-noise ratio increment of over 30 d

Dehydrating process experiment on spent ion-exchange resin sludge by Funda Filter

International Nuclear Information System (INIS)

Hasegawa, Tatsuo; Ishino, Kazuyuki

1977-01-01

In nuclear power plants, Funda Filters are employed to dehydrate spent powdery ion-exchange resin sludge. The Funda Filter is very effective for eliminating small rust components contained in spent powdery resin slurry; however, in the drying process, the complete drying of spent powdery resin is very difficult because the filter cake of resin on the horizontal filter leaf is likely to crack and let out steam and hot air through the cracks. This paper deals with the results of experiments conducted to clarify the detailed phenomena of dehydration so the above problem could be solved. The above experiments were made on the precoating and drying of granular ion-exchange resin slurry that had not yet been put to practical use. The experiments were composed of one fundamental and one operational stage. In the fundamental experiment, the dehydration properties and dehydration mechanism of resins were made clear, and the most effective operational method was established through the operational experiments conducted using large-scale Funda Filter test equipment under various conditions. (auth.)

Nucleation and growth of apatite on NaOH-treated PEEK, HDPE and UHMWPE for artificial cornea materials.

Science.gov (United States)

Pino, M; Stingelin, N; Tanner, K E

2008-11-01

The skirt of an artificial cornea must integrate the implant to the host sclera, a major failure of present devices. Thus, it is highly desirable to encourage the metabolic activity of the cornea by using more bioactive, flexible skirt materials. Here we describe attempts to increase the bioactivity of polyether ether ketone (PEEK), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) films. The effectiveness of different strength NaOH pre-treatments to initiate apatite deposition on PEEK, HDPE and UHMWPE is investigated. We find that exposure of PEEK, HDPE and UHMWPE films to NaOH solutions induces the formation of potential nuclei for apatite (calcium phosphate), from which the growth of an apatite coating is stimulated when subsequently immersing the polymer films in 1.5 strength Simulated Body Fluid (SBF). As immersion time in SBF increases, further nucleation and growth produces a thicker and more compact apatite coating that can be expected to be highly bioactive. Interestingly, the apatite growth is found to also be dependent on both the concentration of NaOH solution and the structure of the polymer surface.

Control of Scar Tissue Formation in the Cornea: Strategies in Clinical and Corneal Tissue Engineering

Directory of Open Access Journals (Sweden)

Samantha L. Wilson

2012-09-01

Full Text Available Corneal structure is highly organized and unified in architecture with structural and functional integration which mediates transparency and vision. Disease and injury are the second most common cause of blindness affecting over 10 million people worldwide. Ninety percent of blindness is permanent due to scarring and vascularization. Scarring caused via fibrotic cellular responses, heals the tissue, but fails to restore transparency. Controlling keratocyte activation and differentiation are key for the inhibition and prevention of fibrosis. Ophthalmic surgery techniques are continually developing to preserve and restore vision but corneal regression and scarring are often detrimental side effects and long term continuous follow up studies are lacking or discouraging. Appropriate corneal models may lead to a reduced need for corneal transplantation as presently there are insufficient numbers or suitable tissue to meet demand. Synthetic optical materials are under development for keratoprothesis although clinical use is limited due to implantation complications and high rejection rates. Tissue engineered corneas offer an alternative which more closely mimic the morphological, physiological and biomechanical properties of native corneas. However, replication of the native collagen fiber organization and retaining the phenotype of stromal cells which prevent scar-like tissue formation remains a challenge. Careful manipulation of culture environments are under investigation to determine a suitable environment that simulates native ECM organization and stimulates keratocyte migration and generation.

Oxidative Stress to the Cornea, Changes in Corneal Optical Properties, and Advances in Treatment of Corneal Oxidative Injuries

Czech Academy of Sciences Publication Activity Database

Čejka, Čestmír; Čejková, Jitka

2015-01-01

Roč. 2015, Mar 11 (2015), s. 591530 ISSN 1942-0900 R&D Projects: GA ČR(CZ) GA14-12580S Keywords : experimental autoimmune uveitis * eye sjogrens-syndrome * rabbit cornea * aldehyde dehydrogenase * uvb rays * glutathione-peroxidase * superoxide-dismutase * refractive-index * reactive oxygen * alkali-burn Subject RIV: FF - HEENT, Dentistry Impact factor: 4.492, year: 2015

Alexander fractional differential window filter for ECG denoising.

Science.gov (United States)

Verma, Atul Kumar; Saini, Indu; Saini, Barjinder Singh

2018-06-01

.0126, 0.08493, and 0.10336 for the ECG signal corrupted by the different type of noises. The versatility of the proposed AFDW filter is also validated by its application on the ECG signal from MIT-BIH database corrupted by the combination of the noises as well as on the real noisy ECG signals are taken from MIT-BIH ID database. Furthermore, the comparative study has also been done between the proposed AFDW filter and existing state of the art denoising algorithms. The results clearly prove the supremacy of our proposed AFDW filter.

Experimental study of filter cake formation on different filter media

International Nuclear Information System (INIS)

Saleem, M.

2009-01-01

Removal of particulate matter from gases generated in the process industry is important for product recovery as well as emission control. Dynamics of filtration plant depend on operating conditions. The models, that predict filter plant behaviour, involve empirical resistance parameters which are usually derived from limited experimental data and are characteristics of the filter media and filter cake (dust deposited on filter medium). Filter cake characteristics are affected by the nature of filter media, process parameters and mode of filter regeneration. Removal of dust particles from air is studied in a pilot scale jet pulsed bag filter facility resembling closely to the industrial filters. Limestone dust and ambient air are used in this study with two widely different filter media. All important parameters like pressure drop, gas flow rate, dust settling, are recorded continuously at 1s interval. The data is processed for estimation of the resistance parameters. The pressure drop rise on test filter media is compared. Results reveal that the surface of filter media has an influence on pressure drop rise (concave pressure drop rise). Similar effect is produced by partially jet pulsed filter surface. Filter behaviour is also simulated using estimated parameters and a simplified model and compared with the experimental results. Distribution of cake area load is therefore an important aspect of jet pulse cleaned bag filter modeling. Mean specific cake resistance remains nearly constant on thoroughly jet pulse cleaned membrane coated filter bags. However, the trend can not be confirmed without independent cake height and density measurements. Thus the results reveal the importance of independent measurements of cake resistance. (author)

A role for smoothened during murine lens and cornea development.

Directory of Open Access Journals (Sweden)

Janet J Y Choi

Full Text Available Various studies suggest that Hedgehog (Hh signalling plays roles in human and zebrafish ocular development. Recent studies (Kerr et al., Invest Ophthalmol Vis Sci. 2012; 53, 3316-30 showed that conditionally activating Hh signals promotes murine lens epithelial cell proliferation and disrupts fibre differentiation. In this study we examined the expression of the Hh pathway and the requirement for the Smoothened gene in murine lens development. Expression of Hh pathway components in developing lens was examined by RT-PCR, immunofluorescence and in situ hybridisation. The requirement of Smo in lens development was determined by conditional loss-of-function mutations, using LeCre and MLR10 Cre transgenic mice. The phenotype of mutant mice was examined by immunofluorescence for various markers of cell cycle, lens and cornea differentiation. Hh pathway components (Ptch1, Smo, Gli2, Gli3 were detected in lens epithelium from E12.5. Gli2 was particularly localised to mitotic nuclei and, at E13.5, Gli3 exhibited a shift from cytosol to nucleus, suggesting distinct roles for these transcription factors. Conditional deletion of Smo, from ∼E12.5 (MLR10 Cre did not affect ocular development, whereas deletion from ∼E9.5 (LeCre resulted in lens and corneal defects from E14.5. Mutant lenses were smaller and showed normal expression of p57Kip2, c-Maf, E-cadherin and Pax6, reduced expression of FoxE3 and Ptch1 and decreased nuclear Hes1. There was normal G1-S phase but decreased G2-M phase transition at E16.5 and epithelial cell death from E14.5-E16.5. Mutant corneas were thicker due to aberrant migration of Nrp2+ cells from the extraocular mesenchyme, resulting in delayed corneal endothelial but normal epithelial differentiation. These results indicate the Hh pathway is required during a discrete period (E9.5-E12.5 in lens development to regulate lens epithelial cell proliferation, survival and FoxE3 expression. Defective corneal development occurs

MST Filterability Tests

Energy Technology Data Exchange (ETDEWEB)

Poirier, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Burket, P. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Duignan, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-03-12

The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). The low filter flux through the ARP has limited the rate at which radioactive liquid waste can be treated. Recent filter flux has averaged approximately 5 gallons per minute (gpm). Salt Batch 6 has had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. In addition, at the time the testing started, SRR was assessing the impact of replacing the 0.1 micron filter with a 0.5 micron filter. This report describes testing of MST filterability to investigate the impact of filter pore size and MST particle size on filter flux and testing of filter enhancers to attempt to increase filter flux. The authors constructed a laboratory-scale crossflow filter apparatus with two crossflow filters operating in parallel. One filter was a 0.1 micron Mott sintered SS filter and the other was a 0.5 micron Mott sintered SS filter. The authors also constructed a dead-end filtration apparatus to conduct screening tests with potential filter aids and body feeds, referred to as filter enhancers. The original baseline for ARP was 5.6 M sodium salt solution with a free hydroxide concentration of approximately 1.7 M.3 ARP has been operating with a sodium concentration of approximately 6.4 M and a free hydroxide concentration of approximately 2.5 M. SRNL conducted tests varying the concentration of sodium and free hydroxide to determine whether those changes had a significant effect on filter flux. The feed slurries for the MST filterability tests were composed of simple salts (NaOH, NaNO₂, and NaNO₃) and MST (0.2 – 4.8 g/L). The feed slurry for the filter enhancer tests contained simulated salt batch 6 supernate, MST, and filter enhancers.

Cross-linking da cornea: protocolo padrão

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Marcony R. Santhiago

Full Text Available RESUMO O objetivo desta revisão é de determinar as indicações e eficácia da cirurgia que promove novas ligações covalentes entre as fibras de colágeno da córnea, conhecida como Cross-Linking (CXL, assim como esclarecer seus objetivos. O ceratocone é uma doença ectasica da córnea, bilateral, assimétrica, que, principalmente, cursa com encurvamento e afinamentos progressivo, e se inicia em geral na segunda década de vida. O uso primário do CXL tem sido na interrupção da progressão do Ceratocone. Apesar do conhecido encurvamento no estroma da córnea ocorrer nesses pacientes, a fisiopatologia por trás do ceratocone ainda é desconhecida e parece ser multifatorial. Pela evidencia literária disponível até o momento, o CXL da córnea esta, portanto indicado nos pacientes com doença em progressão. Concluímos que existe evidencia suficiente para afirmar que o CXL da córnea é eficaz na estabilização da doença ectásica da cornea.

Effect of biometric characteristics on biomechanical properties of the cornea in cataract patient

Directory of Open Access Journals (Sweden)

Xue-Fei Song

2016-06-01

Full Text Available AIM: To determine the impact of biometric characteristics on the biomechanical properties of the human cornea using the ocular response analyzer (ORA and standard comprehensive ophthalmic examinations before and after standard phacoemulsification. METHODS: This study comprised 54 eyes with cataract with significant lens opacification in stages I or II that underwent phacoemulsification (2.8 mm incision. Corneal hysteresis (CH, corneal resistance factor (CRF, Goldmann-correlated intraocular pressure (IOPg, and corneal-compensated intraocular pressure (IOPcc were measured by ORA preoperatively and at 1mo postoperatively. Biometric characteristics were derived from corneal topography [TMS-5, anterior equivalent (EQTMS and cylindric (CYLTMS power], corneal tomography [Casia, anterior and posterior equivalent (EQaCASIC, EQpCASIA and cylindric (CYLaCASIA, CYLpCASIA power], keratometry [IOLMaster, anterior equivalent (EQIOL and cylindric (CYLIOL power] and autorefractor [anterior equivalent (EQAR]. Results from ORA were analyzed and correlated with those from all other examinations taken at the same time point. RESULTS: Preoperatively, CH correlated with EQpCASIA and CYLpCASIA only (P=0.001, P=0.002. Postoperatively, IOPg and IOPcc correlated with all equivalent powers (EQTMS, EQIOL, EQAR, EQaCASIA and EQpCASIA (P=0.001, P=0.007, P=0.001, P=0.015, P=0.03 for IOPg and P<0.001, P=0.003, P<0.001, P=0.009, P=0.014 for IOPcc. CH correlated postoperatively with EQaCASIA and EQpCASIC only (P=0.021, P=0.022. CONCLUSION: Biometric characteristics may significantly affect biomechanical properties of the cornea in terms of CH, IOPcc and IOPg before, but even more after cataract surgery.

Numerical study of canister filters with alternatives filter cap configurations

Science.gov (United States)

Mohammed, A. N.; Daud, A. R.; Abdullah, K.; Seri, S. M.; Razali, M. A.; Hushim, M. F.; Khalid, A.

2017-09-01

Air filtration system and filter play an important role in getting a good quality air into turbo machinery such as gas turbine. The filtration system and filter has improved the quality of air and protect the gas turbine part from contaminants which could bring damage. During separation of contaminants from the air, pressure drop cannot be avoided but it can be minimized thus helps to reduce the intake losses of the engine [1]. This study is focused on the configuration of the filter in order to obtain the minimal pressure drop along the filter. The configuration used is the basic filter geometry provided by Salutary Avenue Manufacturing Sdn Bhd. and two modified canister filter cap which is designed based on the basic filter model. The geometries of the filter are generated by using SOLIDWORKS software and Computational Fluid Dynamics (CFD) software is used to analyse and simulates the flow through the filter. In this study, the parameters of the inlet velocity are 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s. The total pressure drop produce by basic, modified filter 1 and 2 is 292.3 Pa, 251.11 Pa and 274.7 Pa. The pressure drop reduction for the modified filter 1 is 41.19 Pa and 14.1% lower compared to basic filter and the pressure drop reduction for modified filter 2 is 17.6 Pa and 6.02% lower compared to the basic filter. The pressure drops for the basic filter are slightly different with the Salutary Avenue filter due to limited data and experiment details. CFD software are very reliable in running a simulation rather than produces the prototypes and conduct the experiment thus reducing overall time and cost in this study.

Image-Based Multi-Target Tracking through Multi-Bernoulli Filtering with Interactive Likelihoods.

Science.gov (United States)

Hoak, Anthony; Medeiros, Henry; Povinelli, Richard J

2017-03-03

We develop an interactive likelihood (ILH) for sequential Monte Carlo (SMC) methods for image-based multiple target tracking applications. The purpose of the ILH is to improve tracking accuracy by reducing the need for data association. In addition, we integrate a recently developed deep neural network for pedestrian detection along with the ILH with a multi-Bernoulli filter. We evaluate the performance of the multi-Bernoulli filter with the ILH and the pedestrian detector in a number of publicly available datasets (2003 PETS INMOVE, Australian Rules Football League (AFL) and TUD-Stadtmitte) using standard, well-known multi-target tracking metrics (optimal sub-pattern assignment (OSPA) and classification of events, activities and relationships for multi-object trackers (CLEAR MOT)). In all datasets, the ILH term increases the tracking accuracy of the multi-Bernoulli filter.

Embryonic chicken cornea and cartilage synthesize type IX collagen molecules with different amino-terminal domains.

OpenAIRE

Svoboda, K K; Nishimura, I; Sugrue, S P; Ninomiya, Y; Olsen, B R

1988-01-01

We have analyzed embryonic chicken cornea for the presence of type IX collagen mRNA and protein. Using RNA transfer blot analysis, we demonstrate that alpha 1(IX) and alpha 2(IX) mRNAs are expressed by corneal epithelial cells at the time that the primary stromal components are synthesized. The levels of the mRNAs decrease with increasing developmental age and are barely detectable at day 11 of development. In contrast, type IX collagen protein is detectable by immunofluorescence at days 5 an...

The development of a HEPA filter with improved dust holding characteristics

International Nuclear Information System (INIS)

Dyment, J.; Hamblin, C.

1995-01-01

A limitation of the HEPA filters used in the extract of nuclear facilities is their relatively low capacity for captured dust. The costs associated with the disposal of a typical filter means that there are clear incentives to extend filter life. The work described in this report are the initial stages in the development of a filter which incorporates a medium which enhances its dust holding capacity. Experimental equipment was installed to enable the dust loading characteristics of candidate media to be compared with those of the glass fibre based papers currently used in filter construction. These tests involved challenging representative samples of the media with an air stream containing a controlled concentration of thermally generated sodium chloride particles. The dust loading characteristics of the media were then compared in terms of the rate of increasing in pressure differential. A number of open-quotes graded densityclose quotes papers were subsequently identified which appeared to offer significant improvements in dust holding. In the second phase of the programme deep-pleat filters (1,700 M 3 h -1 ) incorporating graded density papers were manufactured and tested. Improvements of up to 50% were observed in their capacity for the sub-micron sodium chloride test dust. Smaller differences (15%) were measured when a coarser, carbon black, challenge was used. This is attributed to the differences in the particles sizes of the two dusts

Ancient whales did not filter feed with their teeth.

Science.gov (United States)

Hocking, David P; Marx, Felix G; Fitzgerald, Erich M G; Evans, Alistair R

2017-08-01

The origin of baleen whales (Mysticeti), the largest animals on Earth, is closely tied to their signature filter-feeding strategy. Unlike their modern relatives, archaic whales possessed a well-developed, heterodont adult dentition. How these teeth were used, and what role their function and subsequent loss played in the emergence of filter feeding, is an enduring mystery. In particular, it has been suggested that elaborate tooth crowns may have enabled stem mysticetes to filter with their postcanine teeth in a manner analogous to living crabeater and leopard seals, thereby facilitating the transition to baleen-assisted filtering. Here we show that the teeth of archaic mysticetes are as sharp as those of terrestrial carnivorans, raptorial pinnipeds and archaeocetes, and thus were capable of capturing and processing prey. By contrast, the postcanine teeth of leopard and crabeater seals are markedly blunter, and clearly unsuited to raptorial feeding. Our results suggest that mysticetes never passed through a tooth-based filtration phase, and that the use of teeth and baleen in early whales was not functionally connected. Continued selection for tooth sharpness in archaic mysticetes is best explained by a feeding strategy that included both biting and suction, similar to that of most living pinnipeds and, probably, early toothed whales (Odontoceti). © 2017 The Authors.

Repeatability of pachymetric mapping using fourier domain optical coherence tomography in corneas with opacities.

Science.gov (United States)

Samy El Gendy, Nehal M; Li, Yan; Zhang, Xinbo; Huang, David

2012-04-01

To evaluate the repeatability of Fourier domain optical coherence tomography (OCT) pachymetric mapping in patients with corneal opacities and to assess the reliability of Fourier domain OCT with 830 nm wavelength as a pachymetric measurement tool in opaque corneas. A Fourier domain OCT system was used to map the corneal thickness of patients with corneal scars or dystrophy. A retrospective study of a consecutive series was conducted. The repeatability was measured using pooled standard deviation of repeated measurements. A slit-scanning tomography device provided pachymetric mapping for comparison. Seventeen eyes of 12 patients with corneal scars (7 trauma and 3 post infection) or dystrophy (2 Reis-Bucklers and 5 granular dystrophy) were included. The posterior corneal boundary was detectable in all cases. The average corneal thickness measured by OCT was 536 ± 89 μm in central 2 mm area, 553 ± 76 μm in pericentral 2- to 5-mm area, and 508 ± 93 μm for the minimum corneal thickness. The slit-scanning tomography central corneal thickness, 433 ± 111 μm, was significantly lower than OCT readings (mean difference -91.1 ± 33.3 μm, P = 0.002). Repeatability of the OCT measurements was 2.1 μm centrally and 1.2 μm pericentrally. Pachymetric mapping with Fourier domain OCT was highly repeatable. Fourier domain OCT is a reliable pachymetric tool in opaque corneas. In comparison, corneal thickness measured by the slit-scanning tomography is significantly thinner than those measured by the Fourier domain OCT in the presence of corneal opacities.

Proteomic Analyses of the Acute Tissue Response for Explant Rabbit Corneas and Engineered Corneal Tissue Models Following In Vitro Exposure to 1540 nm Laser Light

National Research Council Canada - National Science Library

Eurell, T. E; Johnson, T. E; Roach, W. P

2005-01-01

Two-dimensional electrophoresis and histomorphometry were used to determine if equivalent protein changes occurred within native rabbit corneas and engineered corneal tissue models following in vitro...

Evaluating the sustainability of ceramic filters for point-of-use drinking water treatment.

Science.gov (United States)

Ren, Dianjun; Colosi, Lisa M; Smith, James A

2013-10-01

This study evaluates the social, economic, and environmental sustainability of ceramic filters impregnated with silver nanoparticles for point-of-use (POU) drinking water treatment in developing countries. The functional unit for this analysis was the amount of water consumed by a typical household over ten years (37,960 L), as delivered by either the POU technology or a centralized water treatment and distribution system. Results indicate that the ceramic filters are 3-6 times more cost-effective than the centralized water system for reduction of waterborne diarrheal illness among the general population and children under five. The ceramic filters also exhibit better environmental performance for four of five evaluated life cycle impacts: energy use, water use, global warming potential, and particulate matter emissions (PM10). For smog formation potential, the centralized system is preferable to the ceramic filter POU technology. This convergence of social, economic, and environmental criteria offers clear indication that the ceramic filter POU technology is a more sustainable choice for drinking water treatment in developing countries than the centralized treatment systems that have been widely adopted in industrialized countries.

Role of Mesenchymal Stem Cells on Cornea Wound Healing Induced by Acute Alkali Burn

Science.gov (United States)

Yao, Lin; Li, Zhan-rong; Su, Wen-ru; Li, Yong-ping; Lin, Miao-li; Zhang, Wen-xin; Liu, Yi; Wan, Qian; Liang, Dan

2012-01-01

The aim of this study was to investigate the effects of subconjunctivally administered mesenchymal stem cells (MSCs) on corneal wound healing in the acute stage of an alkali burn. A corneal alkali burn model was generated by placing a piece of 3-mm diameter filter paper soaked in NaOH on the right eye of 48 Sprague-Dawley female rats. 24 rats were administered a subconjunctival injection of a suspension of 2×106 MSCs in 0.1 ml phosphate-buffered saline (PBS) on day 0 and day 3 after the corneal alkali burn. The other 24 rats were administered a subconjunctival injection of an equal amount of PBS as a control. Deficiencies of the corneal epithelium and the area of corneal neovascularization (CNV) were evaluated on days 3 and 7 after the corneal alkali burn. Infiltrated CD68+ cells were detected by immunofluorescence staining. The mRNA expression levels of macrophage inflammatory protein-1 alpha (MIP-1α), tumor necrosis factor-alpha (TNF-α), monocyte chemotactic protein-1 (MCP-1) and vascular endothelial growth factor (VEGF) were analyzed using real-time polymerase chain reaction (real-time PCR). In addition, VEGF protein levels were analyzed using an enzyme-linked immunosorbent assay (ELISA). MSCs significantly enhanced the recovery of the corneal epithelium and decreased the CNV area compared with the control group. On day 7, the quantity of infiltrated CD68+ cells was significantly lower in the MSC group and the mRNA levels of MIP-1α, TNF-α, and VEGF and the protein levels of VEGF were also down-regulated. However, the expression of MCP-1 was not different between the two groups. Our results suggest that subconjunctival injection of MSCs significantly accelerates corneal wound healing, attenuates inflammation and reduces CNV in alkaline-burned corneas; these effects were found to be related to a reduction of infiltrated CD68+ cells and the down-regulation of MIP-1α, TNF-α and VEGF. PMID:22363499

Comparison of seropositivity of human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and syphilis among Hospital Cornea Retrieval Programme-Donors versus voluntary cornea donors at a large eye bank in Eastern India.

Science.gov (United States)

Basak, Soham; Basak, Samar K; Biswas, Bani

2017-11-01

To compare the serology profile of donors from Hospital Cornea Retrieval Programme-donors (HCRP-D) and voluntary cornea donors (VC-D) from a large eye bank in Eastern India. This is a retrospective analysis of donor details from January 2011 to December 2016. Donor demographics, cause of death, and serology reports were compiled. Postmortem blood was tested for human immunodeficiency virus 1 and 2 (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), and syphilis using government-approved kits as per the National Programme for Control of Blindness Standards of Eye Banking. Donors for whom serology was not possible were excluded. A total of 4300 of 4353 donors were included of which 74.3% were hospital donors and 25.7% were voluntary donors. A total of 93 (2.2%) donors with 94 seropositive reports were noted: 79 (84.9%) from HCRP-D and 14 (15.1%) from VC-D which was statistically significantly higher (P = 0.02). Among seropositive reports, HIV, HBV, HCV, and syphilis accounted for 12 (12.8%), 38 (40.4%), 36 (38.3%), and eight (8.5%), respectively. There was no correlation between the cause of death and seropositivity. A statistically significant decreasing trend in seroprevalence among hospital donors was observed over the years (5.3% in 2011 to 1.4% in 2016; P = 0.004). Two (0.47%) of 421 hospital donors with prior negative serology were found to be seropositive. Seropositive rates are significantly higher among hospital donors in spite of medical prescreening compared to nonscreened voluntary donors. Serology should be repeated even when prior reports are available.

Controlling flow conditions of test filters in iodine filters

International Nuclear Information System (INIS)

Holmberg, R.; Laine, J.

1979-03-01

Several different iodine filter and test filter designs and experience gained from their operation are presented. For the flow experiments, an iodine filter system equipped with flow regulating and measuring devices was built. In the experiments the influence of the packing method of the iodine sorption material and the influence of the flow regulating and measuring divices upon the flow conditions in the test filters was studied. On the basis of the experiments it has been shown that the flows through the test filters always can be adjusted to a correct value if there only is a high enough pressure difference available across the test filter ducting. As a result of the research, several different methods are presented with which the flows through the test filters in both operating and future iodine sorption system can easily be measured and adjusted to their correct values. (author)

The Rao-Blackwellized Particle Filter: A Filter Bank Implementation

Directory of Open Access Journals (Sweden)

Karlsson Rickard

2010-01-01

Full Text Available For computational efficiency, it is important to utilize model structure in particle filtering. One of the most important cases occurs when there exists a linear Gaussian substructure, which can be efficiently handled by Kalman filters. This is the standard formulation of the Rao-Blackwellized particle filter (RBPF. This contribution suggests an alternative formulation of this well-known result that facilitates reuse of standard filtering components and which is also suitable for object-oriented programming. Our RBPF formulation can be seen as a Kalman filter bank with stochastic branching and pruning.

Convergent Filter Bases

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Coghetto Roland

2015-09-01

Full Text Available We are inspired by the work of Henri Cartan [16], Bourbaki [10] (TG. I Filtres and Claude Wagschal [34]. We define the base of filter, image filter, convergent filter bases, limit filter and the filter base of tails (fr: filtre des sections.

Visual outcomes after deep anterior lamellar keratoplasty using donor corneas without removal of Descemet membrane and endothelium

Directory of Open Access Journals (Sweden)

Tatiana Moura Bastos Prazeres

Full Text Available ABSTRACT Purpose: The optical quality of the interface after deep anterior lamellar keratoplasty (DALK using the big-bubble technique has been shown to be excellent, leading to results comparable to penetrating keratoplasty. However, there is little in the literature with respect to the controversy surrounding the preparation of the donor cornea. The purpose of this study was to evaluate visual acuity (VA in patients with keratoconus who underwent DALK without removal of the donor graft endothelium. Methods: The records of 90 patients who underwent DALK without the removal of the Descemet membrane (DM and endothelium were retrospectively reviewed. Data collected included uncorrected VA (UCVA and spectacle-corrected VA (SCVA at 7, 30, 180 days, and 1 year postoperatively. Contact lens-corrected visual acuity (CLVA was evaluated after 1 year of the procedure. Results: UCVA was significantly better than preoperative values at 7 days (p<0.001, 30 days (p<0.001, 180 days (p<0.001, and 1 year (p<0.001 after surgery. The 1-year postoperative mean SCVA and CLVA also improved when compared with preoperative SCVA (p<0.001 for both. Conclusions: DALK utilizing donor corneas with attached Descemet membrane and endothelium results in satisfactory VA in patients with keratoconus.

Polymicrobial Infection of the Cornea Due to Contact Lens Wear

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Selçuk Sızmaz

2016-04-01

Full Text Available A 38-year-old male presented with pain and redness in his left eye. He had a history of wearing contact lenses. His ophthalmic examination revealed a large corneal ulcer with surrounding infiltrate. Cultures were isolated from the contact lenses, lens solutions, storage cases, and conjunctivae of both eyes and also corneal scrapings of the left eye. Fortified vancomycin and amikacin drops were started hourly. Culture results of conjunctivae of each eye and left cornea were positive for Pseudomonas aeruginosa; cultures from the contact lenses, lens solution and storage case of both eyes revealed Pseudomonas aeruginosa and Alcaligenes xylosoxidans. Polymerase chain reaction of the corneal scraping was positive for Acanthameoba. The topical antibiotics were changed with ones that both bacteria were sensitive to and anti-amoebic therapy was added. The patient had two recurrences following initial presentation despite intensive therapy. Keratitis occurred due to multiple pathogens; the relapsing course despite adequate therapy is potentially associated with this polymicrobial etiology.

Application of DFT Filter Banks and Cosine Modulated Filter Banks in Filtering

Science.gov (United States)

Lin, Yuan-Pei; Vaidyanathan, P. P.

1994-01-01

None given. This is a proposal for a paper to be presented at APCCAS '94 in Taipei, Taiwan. (From outline): This work is organized as follows: Sec. II is devoted to the construction of the new 2m channel under-decimated DFT filter bank. Implementation and complexity of this DFT filter bank are discussed therein. IN a similar manner, the new 2m channel cosine modulated filter bank is discussed in Sec. III. Design examples are given in Sec. IV.

Coenzyme Q10 instilled as eye drops on the cornea reaches the retina and protects retinal layers from apoptosis in a mouse model of kainate-induced retinal damage.

Science.gov (United States)

Lulli, Matteo; Witort, Ewa; Papucci, Laura; Torre, Eugenio; Schipani, Christian; Bergamini, Christian; Dal Monte, Massimo; Capaccioli, Sergio

2012-12-17

To evaluate if coenzyme Q10 (CoQ10) can protect retinal ganglion cells (RGCs) from apoptosis and, when instilled as eye drops on the cornea, if it can reach the retina and exert its antiapoptotic activity in this area in a mouse model of kainate (KA)-induced retinal damage. Rat primary or cultured RGCs were subjected to glutamate (50 μM) or chemical hypoxia (Antimycin A, 200 μM) or serum withdrawal (FBS, 0.5%) in the presence or absence of CoQ10 (10 μM). Cell viability was evaluated by light microscopy and fluorescence-activated cell sorting analyses. Apoptosis was evaluated by caspase 3/7 activity and mitochondrion depolarization tetramethylrhodamine ethyl ester analysis. CoQ10 transfer to the retina following its instillation as eye drops on the cornea was quantified by HPLC. Retinal protection by CoQ10 (10 μM) eye drops instilled on the cornea was then evaluated in a mouse model of KA-induced excitotoxic retinal cell apoptosis by cleaved caspase 3 immunohistofluorescence, caspase 3/7 activity assays, and quantification of inhibition of RGC loss. CoQ10 significantly increased viable cells by preventing RGC apoptosis. Furthermore, when topically applied as eye drops to the cornea, it reached the retina, thus substantially increasing local CoQ10 concentration and protecting retinal layers from apoptosis. The ability of CoQ10 eye drops to protect retinal cells from apoptosis in the mouse model of KA-induced retinal damage suggests that topical CoQ10 may be evaluated in designing therapies for treating apoptosis-driven retinopathies.

Image-Based Multi-Target Tracking through Multi-Bernoulli Filtering with Interactive Likelihoods

Directory of Open Access Journals (Sweden)

Anthony Hoak

2017-03-01

Full Text Available We develop an interactive likelihood (ILH for sequential Monte Carlo (SMC methods for image-based multiple target tracking applications. The purpose of the ILH is to improve tracking accuracy by reducing the need for data association. In addition, we integrate a recently developed deep neural network for pedestrian detection along with the ILH with a multi-Bernoulli filter. We evaluate the performance of the multi-Bernoulli filter with the ILH and the pedestrian detector in a number of publicly available datasets (2003 PETS INMOVE, Australian Rules Football League (AFL and TUD-Stadtmitte using standard, well-known multi-target tracking metrics (optimal sub-pattern assignment (OSPA and classification of events, activities and relationships for multi-object trackers (CLEAR MOT. In all datasets, the ILH term increases the tracking accuracy of the multi-Bernoulli filter.

A Study of Parallel Operation of an active Filter and passive Filters

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim

2002-01-01

This paper reports investigations of the parallel operations of a current controlled active filter and passive filters in a system with current harmonic sources. The task of reactive power and harmonic compensation is shared by the active filter and passive filters. The passive filters are used...... arrangements of the active and passive filters can operate relatively independently, also the compensation flexibility of the active filter can be fully exploited, such as one active filter for several harmonic sources.The simulation studies on various systems have been performed to evaluate the effectiveness...... of the systems. The results show that the power factor is corrected by the passive filters, harmonics are minimized by both active and passive filters and overloading of the filter system can be avoided....

Clear retainer

Directory of Open Access Journals (Sweden)

Priyakorn Chaimongkol

2017-01-01

Full Text Available A clear retainer is a removable retainer that is popular in the present day. Compared with conventional fixed and removable orthodontic retainers, it is a more esthetic, comfortable, and inexpensive appliance. Although several studies have been published about clear retainers, it could be difficult to interpret the results because of the variety of study designs, sample sizes, and research methods. This article is intended to compile the content from previous studies and discuss advantages, disadvantages, fabrication, insertion, and adjustment. Moreover, the effectiveness in maintaining dental position, occlusion, retention protocols, thickness, and survival rate of clear retainers is discussed.

Passive Power Filters

CERN Document Server

Künzi, R.

2015-06-15

Power converters require passive low-pass filters which are capable of reducing voltage ripples effectively. In contrast to signal filters, the components of power filters must carry large currents or withstand large voltages, respectively. In this paper, three different suitable filter struc tures for d.c./d.c. power converters with inductive load are introduced. The formulas needed to calculate the filter components are derived step by step and practical examples are given. The behaviour of the three discussed filters is compared by means of the examples. P ractical aspects for the realization of power filters are also discussed.

Analysis of the effect of the fluid-structure interface on elastic wave velocity in cornea-like structures by OCE and FEM

International Nuclear Information System (INIS)

Han, Zhaolong; Li, Jiasong; Singh, Manmohan; Wu, Chen; Liu, Chih-hao; Raghunathan, Raksha; Larin, Kirill V; Vantipalli, Srilatha; Aglyamov, Salavat R; Twa, Michael D

2016-01-01

Air-pulse optical coherence elastography (OCE) is a promising technique for quantifying biomechanical properties of the cornea. This technique typically involves imaging and analysis of the propagation of the air-pulse induced elastic waves to reconstruct corneal biomechanical properties using an analytical model. However, the effect of the fluid-structure interface (FSI) at the corneal posterior surface on the elastic wave velocity is not accounted for in many models. In this study, we examined the effect of the FSI with OCE experiments on contact lenses with and without fluid in the posterior gap. Finite element models (FEM), also with and without the FSI, were constructed to simulate the elastic wave propagation based on the OCE measurements. The FEM and OCE results were in good agreement demonstrating the feasibility of the method. To further investigate the effect of the FSI, OCE experiments and subsequent FEM simulations were conducted on in situ rabbit corneas before and after rose bengal/green light corneal collagen cross-linking (RGX). Both the OCE experiments and the FE simulations demonstrated that the FSI significantly reduced the group velocity of the elastic wave, and thus, should be considered when determining corneal biomechanical properties from an appropriate mechanical model. By matching the FEM-calculated velocity to the OCE-measured velocity, the corneal elasticity was quantified. The Young’s modulus of the rabbit cornea before RGX was E  =  65  ±  10 kPa at a controlled intraocular pressure (IOP) of 15 mmHg. After RGX, the Young’s modulus increased to E  =  102  ±  7 kPa at the same IOP. (letter)

Particle Kalman Filtering: A Nonlinear Bayesian Framework for Ensemble Kalman Filters*

KAUST Repository

Hoteit, Ibrahim

2012-02-01

This paper investigates an approximation scheme of the optimal nonlinear Bayesian filter based on the Gaussian mixture representation of the state probability distribution function. The resulting filter is similar to the particle filter, but is different from it in that the standard weight-type correction in the particle filter is complemented by the Kalman-type correction with the associated covariance matrices in the Gaussian mixture. The authors show that this filter is an algorithm in between the Kalman filter and the particle filter, and therefore is referred to as the particle Kalman filter (PKF). In the PKF, the solution of a nonlinear filtering problem is expressed as the weighted average of an “ensemble of Kalman filters” operating in parallel. Running an ensemble of Kalman filters is, however, computationally prohibitive for realistic atmospheric and oceanic data assimilation problems. For this reason, the authors consider the construction of the PKF through an “ensemble” of ensemble Kalman filters (EnKFs) instead, and call the implementation the particle EnKF (PEnKF). It is shown that different types of the EnKFs can be considered as special cases of the PEnKF. Similar to the situation in the particle filter, the authors also introduce a resampling step to the PEnKF in order to reduce the risk of weights collapse and improve the performance of the filter. Numerical experiments with the strongly nonlinear Lorenz-96 model are presented and discussed.

The development of a HEPA filter with improved dust holding characteristics

Energy Technology Data Exchange (ETDEWEB)

Dyment, J.; Hamblin, C.

1995-02-01

A limitation of the HEPA filters used in the extract of nuclear facilities is their relatively low capacity for captured dust. The costs associated with the disposal of a typical filter means that there are clear incentives to extend filter life. The work described in this report are the initial stages in the development of a filter which incorporates a medium which enhances its dust holding capacity. Experimental equipment was installed to enable the dust loading characteristics of candidate media to be compared with those of the glass fibre based papers currently used in filter construction. These tests involved challenging representative samples of the media with an air stream containing a controlled concentration of thermally generated sodium chloride particles. The dust loading characteristics of the media were then compared in terms of the rate of increasing in pressure differential. A number of {open_quotes}graded density{close_quotes} papers were subsequently identified which appeared to offer significant improvements in dust holding. In the second phase of the programme deep-pleat filters (1,700 M{sup 3}h{sup {minus}1}) incorporating graded density papers were manufactured and tested. Improvements of up to 50% were observed in their capacity for the sub-micron sodium chloride test dust. Smaller differences (15%) were measured when a coarser, carbon black, challenge was used. This is attributed to the differences in the particles sizes of the two dusts.

Rectifier Filters

Directory of Open Access Journals (Sweden)

Y. A. Bladyko

2010-01-01

Full Text Available The paper contains definition of a smoothing factor which is suitable for any rectifier filter. The formulae of complex smoothing factors have been developed for simple and complex passive filters. The paper shows conditions for application of calculation formulae and filters. 

Biomechanical responses of healthy and keratoconic corneas measured using a noncontact scheimpflug-based tonometer.

Science.gov (United States)

Ali, Noor Q; Patel, Dipika V; McGhee, Charles N J

2014-05-15

To examine the repeatability of measurements obtained using a noncontact Scheimpflug-based tonometer (Corvis ST) and investigate potential differences in these parameters between healthy and keratoconic (KC) corneas. Forty-five keratoconic eyes and 103 healthy eyes were examined using biomicroscopy, corneal tomography and the Corvis ST (CST). Intraocular pressure and central corneal thickness (CCT) were highly repeatable (intraclass correlation [ICC] > 0.70, coefficient of variation [CV] 0.60, CV < 0.20). There was no association between DA and age, sex, or ethnicity in healthy eyes. There was a greater mean DA in the KC group compared with 46 age-matched healthy eyes (KC 1.37 ± 0.21 mm, healthy 1.05 ± 0.11 mm, P < 0.001). Multivariate analysis showed DA in KC was predicted by IOP, CCT, and the steepest simulated keratometry value (P = 0.03, P = 0.03, P = 0.001 respectively, R(2) = 0.75). A subgroup analysis of healthy and KC eyes with comparable mean CCT and IOP highlighted a statistically significant difference in mean DA (KC 1.25 ± 0.08 mm, thin healthy 1.13 ± 0.09 mm, P = 0.006). Receiver-operating characteristic analysis showed an area under the curve of 0.77 (95% CI 0.61-0.93, P = 0.006) but no ideal cutoff value for DA. Key parameters assessed by the CST are repeatable. Keratoconus is associated with greater DA than in healthy eyes, even when controlled for CCT and IOP. Deformation amplitude may be a useful adjunct in keratoconus assessment and monitoring, but cannot solely discriminate between healthy and keratoconic corneas. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Comparison of seropositivity of human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and syphilis among Hospital Cornea Retrieval Programme-Donors versus voluntary cornea donors at a large eye bank in Eastern India

Directory of Open Access Journals (Sweden)

Soham Basak

2017-01-01

Full Text Available Purpose: To compare the serology profile of donors from Hospital Cornea Retrieval Programme-donors (HCRP-D and voluntary cornea donors (VC-D from a large eye bank in Eastern India. Methods: This is a retrospective analysis of donor details from January 2011 to December 2016. Donor demographics, cause of death, and serology reports were compiled. Postmortem blood was tested for human immunodeficiency virus 1 and 2 (HIV, hepatitis B virus (HBV, hepatitis C virus (HCV, and syphilis using government-approved kits as per the National Programme for Control of Blindness Standards of Eye Banking. Donors for whom serology was not possible were excluded. Results: A total of 4300 of 4353 donors were included of which 74.3% were hospital donors and 25.7% were voluntary donors. A total of 93 (2.2% donors with 94 seropositive reports were noted: 79 (84.9% from HCRP-D and 14 (15.1% from VC-D which was statistically significantly higher (P = 0.02. Among seropositive reports, HIV, HBV, HCV, and syphilis accounted for 12 (12.8%, 38 (40.4%, 36 (38.3%, and eight (8.5%, respectively. There was no correlation between the cause of death and seropositivity. A statistically significant decreasing trend in seroprevalence among hospital donors was observed over the years (5.3% in 2011 to 1.4% in 2016; P = 0.004. Two (0.47% of 421 hospital donors with prior negative serology were found to be seropositive. Conclusion: Seropositive rates are significantly higher among hospital donors in spite of medical prescreening compared to nonscreened voluntary donors. Serology should be repeated even when prior reports are available.

Retina-Inspired Filter.

Science.gov (United States)

Doutsi, Effrosyni; Fillatre, Lionel; Antonini, Marc; Gaulmin, Julien

2018-07-01

This paper introduces a novel filter, which is inspired by the human retina. The human retina consists of three different layers: the Outer Plexiform Layer (OPL), the inner plexiform layer, and the ganglionic layer. Our inspiration is the linear transform which takes place in the OPL and has been mathematically described by the neuroscientific model "virtual retina." This model is the cornerstone to derive the non-separable spatio-temporal OPL retina-inspired filter, briefly renamed retina-inspired filter, studied in this paper. This filter is connected to the dynamic behavior of the retina, which enables the retina to increase the sharpness of the visual stimulus during filtering before its transmission to the brain. We establish that this retina-inspired transform forms a group of spatio-temporal Weighted Difference of Gaussian (WDoG) filters when it is applied to a still image visible for a given time. We analyze the spatial frequency bandwidth of the retina-inspired filter with respect to time. It is shown that the WDoG spectrum varies from a lowpass filter to a bandpass filter. Therefore, while time increases, the retina-inspired filter enables to extract different kinds of information from the input image. Finally, we discuss the benefits of using the retina-inspired filter in image processing applications such as edge detection and compression.

Analysis of two precipitation methods on the yield, structural features and activity of sulfated polysaccharides from Gracilaria cornea (Rhodophyta

Directory of Open Access Journals (Sweden)

Ricardo Basto Souza

2015-03-01

Full Text Available The global demand for natural products from seaweeds has increased worldwide; however, no description of the use of isoamly alcohol (IAA for obtaining of sulfated polysaccharides (SPs has been reported. We investigated the efficiency of two precipitation methods (M in obtaining SPs from the red seaweed Gracilaria cornea. SPs enzymatically isolated were concentrated with cetylpyridinium chloride (M I or IAA (M II and extracts were examined with regard to their yield, structural features and in vitro effects on the activated partial thromboplastin time (APTT using normal human plasma and standard heparin (193 IU mg-1. Yield difference reached 12.99%. Quantitative determination of sulfate was similar between the two methods (̴ 26%, but extracts revealed different pattern on charge density by agarose gel electrophoresis. Whereas both extracts revealed as agarocolloids, alternative M II was also efficient for lipids, proteins and nucleic acids according to the infrared analysis. Extracts had virtually no effect on APPT (1.95 and 2 IU mg-1 for M I and M II, respectively. The results revealed IAA as an alternative solvent for obtaining SPs from the red seaweed G. cornea, depending on the industry’ usage criterion.

Braile vena cava filter and greenfield filter in terms of centralization.

Science.gov (United States)

de Godoy, José Maria Pereira; Menezes da Silva, Adinaldo A; Reis, Luis Fernando; Miquelin, Daniel; Torati, José Luis Simon

2013-01-01

The aim of this study was to evaluate complications experienced during implantation of the Braile Vena Cava filter (VCF) and the efficacy of the centralization mechanism of the filter. This retrospective cohort study evaluated all Braile Biomédica VCFs implanted from 2004 to 2009 in Hospital de Base Medicine School in São José do Rio Preto, Brazil. Of particular concern was the filter's symmetry during implantation and complications experienced during the procedure. All the angiographic examinations performed during the implantation of the filters were analyzed in respect to the following parameters: migration of the filter, non-opening or difficulties in the implantation and centralization of the filter. A total of 112 Braile CVFs were implanted and there were no reports of filter opening difficulties or in respect to migration. Asymmetry was observed in 1/112 (0.9%) cases. A statistically significant difference was seen on comparing historical data on decentralization of the Greenfield filter with the data of this study. The Braile Biomédico filter is an evolution of the Greenfield filter providing improved embolus capture and better implantation symmetry.

Evaluation of Biomechanical Changes in Myopia Patients with Unsatisfactory Corneas After Femto Second-Laser In Situ Keratomileusis (FS-LASIK) Concurrent with Accelerated Corneal Collagen Cross-Linking Using Corvis-ST: Two-Year Follow-Up Results.

Science.gov (United States)

Xu, Weiwei; Tao, Ye; Wang, Liqiang; Huang, Yifei

2017-07-27

BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled. The patients were assigned to femtosecond-laser in situ keratomileusis concurrent with accelerated corneal collagen crosslinking (FS-LASIK-ACXL). The follow-up duration was 24 months. Manifest refraction, uncorrected (UDVA), and corrected distance visual acuity (CDVA), ultra-high-speed camera (Corvis-ST), corneal topography, anterior segment OCT (AS-OCT), Pentacam, and endothelial cell density (ECD) were examined before and after the operation. The corneal biomechanical and refractive data was analyzed using SAS9.3. Data were analyzed through normal distribution test and variance of analysis. The difference was considered as statistically significant when pLASIK-ACXL operation. The values of first applanation length (A1L), the second applanation length (A2L), the first applanation velocity (A1V), the second applanation velocity (A2V), deformation amplitude (DA), highest concavity peak distance (PD), and radius of curvature at the time of highest concavity (HCR) did not show significant difference after the operation. CONCLUSIONS FS-LASIK-ACXL is an effective and safe surgery for improving visual acuity for myopic patients with thin corneas, and it does not increase the risk of iatrogenic keratectasia.

Balanced microwave filters

CERN Document Server

Hong, Jiasheng; Medina, Francisco; Martiacuten, Ferran

2018-01-01

This book presents and discusses strategies for the design and implementation of common-mode suppressed balanced microwave filters, including, narrowband, wideband, and ultra-wideband filters This book examines differential-mode, or balanced, microwave filters by discussing several implementations of practical realizations of these passive components. Topics covered include selective mode suppression, designs based on distributed and semi-lumped approaches, multilayer technologies, defect ground structures, coupled resonators, metamaterials, interference techniques, and substrate integrated waveguides, among others. Divided into five parts, Balanced Microwave Filters begins with an introduction that presents the fundamentals of balanced lines, circuits, and networks. Part 2 covers balanced transmission lines with common-mode noise suppression, including several types of common-mode filters and the application of such filters to enhance common-mode suppression in balanced bandpass filters. Next, Part 3 exa...

Backflushable filter insert

International Nuclear Information System (INIS)

Keith, R.C.; Vandenberg, T.; Randolph, M.C.; Lewis, T.B.; Gillis, P.J. Jr.

1988-01-01

Filter elements are mounted on a tube plate beneath an accumulator chamber whose wall is extended by skirt and flange to form a closure for the top of pressure vessel. The accumulator chamber is annular around a central pipe which serves as the outlet for filtered water passing from the filter elements. The chamber contains filtered compressed air from supply. Periodically the filtration of water is stopped and vessel is drained. Then a valve is opened, allowing the accumulated air to flow from chamber up a pipe and down pipe, pushing the filtered water from pipe back through the filter elements to clean them. The accumulator chamber is so proportioned, relative to the volume of the system communicating therewith during backflushing, that the equilibrium pressure during backflushing cannot exceed the pressure rating of the vessel. However a line monitors the pressure at the top of the vessel, and if it rises too far a bleed valve is automatically opened to depressurise the system. The chamber is intended to replace the lid of an existing vessel to convert a filter using filter aid to one using permanent filter elements. (author)

Filter replacement lifetime prediction

Science.gov (United States)

Hamann, Hendrik F.; Klein, Levente I.; Manzer, Dennis G.; Marianno, Fernando J.

2017-10-25

Methods and systems for predicting a filter lifetime include building a filter effectiveness history based on contaminant sensor information associated with a filter; determining a rate of filter consumption with a processor based on the filter effectiveness history; and determining a remaining filter lifetime based on the determined rate of filter consumption. Methods and systems for increasing filter economy include measuring contaminants in an internal and an external environment; determining a cost of a corrosion rate increase if unfiltered external air intake is increased for cooling; determining a cost of increased air pressure to filter external air; and if the cost of filtering external air exceeds the cost of the corrosion rate increase, increasing an intake of unfiltered external air.

Anti-clogging filter system

Science.gov (United States)

Brown, Erik P.

2015-05-19

An anti-clogging filter system for filtering a fluid containing large particles and small particles includes an enclosure with at least one individual elongated tubular filter element in the enclosure. The individual elongated tubular filter element has an internal passage, a closed end, an open end, and a filtering material in or on the individual elongated tubular filter element. The fluid travels through the open end of the elongated tubular element and through the internal passage and through the filtering material. An anti-clogging element is positioned on or adjacent the individual elongated tubular filter element and provides a fluid curtain that preferentially directs the larger particulates to one area of the filter material allowing the remainder of the filter material to remain more efficient.

Selection vector filter framework

Science.gov (United States)

Lukac, Rastislav; Plataniotis, Konstantinos N.; Smolka, Bogdan; Venetsanopoulos, Anastasios N.

2003-10-01

We provide a unified framework of nonlinear vector techniques outputting the lowest ranked vector. The proposed framework constitutes a generalized filter class for multichannel signal processing. A new class of nonlinear selection filters are based on the robust order-statistic theory and the minimization of the weighted distance function to other input samples. The proposed method can be designed to perform a variety of filtering operations including previously developed filtering techniques such as vector median, basic vector directional filter, directional distance filter, weighted vector median filters and weighted directional filters. A wide range of filtering operations is guaranteed by the filter structure with two independent weight vectors for angular and distance domains of the vector space. In order to adapt the filter parameters to varying signal and noise statistics, we provide also the generalized optimization algorithms taking the advantage of the weighted median filters and the relationship between standard median filter and vector median filter. Thus, we can deal with both statistical and deterministic aspects of the filter design process. It will be shown that the proposed method holds the required properties such as the capability of modelling the underlying system in the application at hand, the robustness with respect to errors in the model of underlying system, the availability of the training procedure and finally, the simplicity of filter representation, analysis, design and implementation. Simulation studies also indicate that the new filters are computationally attractive and have excellent performance in environments corrupted by bit errors and impulsive noise.

Optimal filter design with progressive genetic algorithm for local damage detection in rolling bearings

Science.gov (United States)

Wodecki, Jacek; Michalak, Anna; Zimroz, Radoslaw

2018-03-01

Harsh industrial conditions present in underground mining cause a lot of difficulties for local damage detection in heavy-duty machinery. For vibration signals one of the most intuitive approaches of obtaining signal with expected properties, such as clearly visible informative features, is prefiltration with appropriately prepared filter. Design of such filter is very broad field of research on its own. In this paper authors propose a novel approach to dedicated optimal filter design using progressive genetic algorithm. Presented method is fully data-driven and requires no prior knowledge of the signal. It has been tested against a set of real and simulated data. Effectiveness of operation has been proven for both healthy and damaged case. Termination criterion for evolution process was developed, and diagnostic decision making feature has been proposed for final result determinance.

Changing ventilation filters

International Nuclear Information System (INIS)

Hackney, S.

1980-01-01

A filter changing unit has a door which interlocks with the door of a filter chamber so as to prevent contamination of the outer surfaces of the doors by radioactive material collected on the filter element and a movable support which enables a filter chamber thereonto to be stored within the unit in such a way that the doors of the unit and the filter chamber can be replaced. The door pivots and interlocks with another door by means of a bolt, a seal around the periphery lip of the first door engages the periphery of the second door to seal the gap. A support pivots into a lower filter element storage position. Inspection windows and glove ports are provided. The unit is releasably connected to the filter chamber by bolts engaging in a flange provided around an opening. (author)

Preparation of affordable and multifunctional clay-based ceramic filter matrix for treatment of drinking water.

Science.gov (United States)

Shivaraju, H Puttaiah; Egumbo, Henok; Madhusudan, P; Anil Kumar, K M; Midhun, G

2018-02-01

Affordable clay-based ceramic filters with multifunctional properties were prepared using low-cost and active ingredients. The characterization results clearly revealed well crystallinity, structural elucidation, extensive porosity, higher surface area, higher stability, and durability which apparently enhance the treatment efficiency. The filtration rates of ceramic filter were evaluated under gravity and the results obtained were compared with a typical gravity slow sand filter (GSSF). All ceramic filters showed significant filtration rates of about 50-180 m/h, which is comparatively higher than the typical GSSF. Further, purification efficiency of clay-based ceramic filters was evaluated by considering important drinking water parameters and contaminants. A significant removal potential was achieved by the clay-based ceramic filter with 25% and 30% activated carbon along with active agents. Desired drinking water quality parameters were achieved by potential removal of nitrite (98.5%), nitrate (80.5%), total dissolved solids (62%), total hardness (55%), total organic pollutants (89%), and pathogenic microorganisms (100%) using ceramic filters within a short duration. The remarkable purification and disinfection efficiencies were attributed to the extensive porosity (0.202 cm 3  g -1 ), surface area (124.61 m 2  g -1 ), stability, and presence of active nanoparticles such as Cu, TiO 2 , and Ag within the porous matrix of the ceramic filter.

Device for automatic filter changing. Einrichtung zum selbsttaetigen Wechseln eines Filters

Energy Technology Data Exchange (ETDEWEB)

Matschoss, V; Naschwitz, A; Wild, H

1984-01-05

A filter is moved from a store to an aerosol pipe by a lifting device and is clamped there. At the end of the operating period, the lifting device moves a new filter to a parking place. Control is from limit switches of the lifting, clamping and thrust devices and the position control of the store is by the limit switches. The filter changing device is enclosed in a gastight case, prevents blockage of a filter and makes it possible to set a certain operating period, to change the filter without interrupting the aerosol flow and to measure each filter in the sequence of operation outside the aerosol flow.

Improving Image Matching by Reducing Surface Reflections Using Polarising Filter Techniques

Science.gov (United States)

Conen, N.; Hastedt, H.; Kahmen, O.; Luhmann, T.

2018-05-01

In dense stereo matching applications surface reflections may lead to incorrect measurements and blunders in the resulting point cloud. To overcome the problem of disturbing reflexions polarising filters can be mounted on the camera lens and light source. Reflections in the images can be suppressed by crossing the polarising direction of the filters leading to homogeneous illuminated images and better matching results. However, the filter may influence the camera's orientation parameters as well as the measuring accuracy. To quantify these effects, a calibration and an accuracy analysis is conducted within a spatial test arrangement according to the German guideline VDI/VDE 2634.1 (2002) using a DSLR with and without polarising filter. In a second test, the interior orientation is analysed in more detail. The results do not show significant changes of the measuring accuracy in object space and only very small changes of the interior orientation (Δc ≤ 4 μm) with the polarising filter in use. Since in medical applications many tiny reflections are present and impede robust surface measurements, a prototypic trinocular endoscope is equipped with polarising technique. The interior and relative orientation is determined and analysed. The advantage of the polarising technique for medical image matching is shown in an experiment with a moistened pig kidney. The accuracy and completeness of the resulting point cloud can be improved clearly when using polarising filters. Furthermore, an accuracy analysis using a laser triangulation system is performed and the special reflection properties of metallic surfaces are presented.

IMPROVING IMAGE MATCHING BY REDUCING SURFACE REFLECTIONS USING POLARISING FILTER TECHNIQUES

Directory of Open Access Journals (Sweden)

N. Conen

2018-05-01

Full Text Available In dense stereo matching applications surface reflections may lead to incorrect measurements and blunders in the resulting point cloud. To overcome the problem of disturbing reflexions polarising filters can be mounted on the camera lens and light source. Reflections in the images can be suppressed by crossing the polarising direction of the filters leading to homogeneous illuminated images and better matching results. However, the filter may influence the camera’s orientation parameters as well as the measuring accuracy. To quantify these effects, a calibration and an accuracy analysis is conducted within a spatial test arrangement according to the German guideline VDI/VDE 2634.1 (2002 using a DSLR with and without polarising filter. In a second test, the interior orientation is analysed in more detail. The results do not show significant changes of the measuring accuracy in object space and only very small changes of the interior orientation (Δc ≤ 4 μm with the polarising filter in use. Since in medical applications many tiny reflections are present and impede robust surface measurements, a prototypic trinocular endoscope is equipped with polarising technique. The interior and relative orientation is determined and analysed. The advantage of the polarising technique for medical image matching is shown in an experiment with a moistened pig kidney. The accuracy and completeness of the resulting point cloud can be improved clearly when using polarising filters. Furthermore, an accuracy analysis using a laser triangulation system is performed and the special reflection properties of metallic surfaces are presented.

Sensory pollution from bag-type fiberglass ventilation filters: Conventional filter compared with filters containing various amounts of activated carbon

DEFF Research Database (Denmark)

Bekö, Gabriel; Fadeyi, M.O.; Clausen, Geo

2009-01-01

filter and three modifications of a bag-type fiberglass combination filter: the "Heavy" corresponded to a commercially available filter containing 400 g of carbon per square meter of filter area, the "Medium" contained half as much carbon (200 g/m(2)), and the "Light" contained a quarter as much carbon...

Coupled biomechanical response of the cornea assessed by non-contact tonometry. A simulation study.

Directory of Open Access Journals (Sweden)

Miguel Á Ariza-Gracia

Full Text Available The mechanical response of the cornea subjected to a non-contact air-jet tonometry diagnostic test represents an interplay between its geometry, the corneal material behavior and the loading. The objective is to study this interplay to better understand and interpret the results obtained with a non-contact tonometry test. A patient-specific finite element model of a healthy eye, accounting for the load free configuration, was used. The corneal tissue was modeled as an anisotropic hyperelastic material with two preferential directions. Three different sets of parameters within the human experimental range obtained from inflation tests were considered. The influence of the IOP was studied by considering four pressure levels (10-28 mmHg whereas the influence of corneal thickness was studied by inducing a uniform variation (300-600 microns. A Computer Fluid Dynamics (CFD air-jet simulation determined pressure loading exerted on the anterior corneal surface. The maximum apex displacement showed a linear variation with IOP for all materials examined. On the contrary, the maximum apex displacement followed a cubic relation with corneal thickness. In addition, a significant sensitivity of the apical displacement to the corneal stiffness was also obtained. Explanation to this behavior was found in the fact that the cornea experiences bending when subjected to an air-puff loading, causing the anterior surface to work in compression whereas the posterior surface works in tension. Hence, collagen fibers located at the anterior surface do not contribute to load bearing. Non-contact tonometry devices give useful information that could be misleading since the corneal deformation is the result of the interaction between the mechanical properties, IOP, and geometry. Therefore, a non-contact tonometry test is not sufficient to evaluate their individual contribution and a complete in-vivo characterization would require more than one test to independently determine

GASDRA: Galaxy Spectrum Dynamic Range Analysis for Photometric Redshift Filter Partition Optimization

Energy Technology Data Exchange (ETDEWEB)

Vicente, J. de; Sanchez, E.; Sevilla, I.; Castilla, J.; Ponce, R.; Sanchez, F. J.

2012-04-11

The photometric redshift is an active area of research. It is becoming the preferred method for redshift measurement above spectroscopy one for large surveys. In these surveys, the requirement in redshift precision is relaxed in benefit of obtaining the measurements of large number of galaxies. One of the more relevant decisions to be taken in the design of a photometric redshift experiment is the number of filters since it affects deeply to the precision and survey time. Currently, there is not a clear method for evaluating the impact in both precision and exposure time of a determined filter partition set and usually it is determined by detailed simulations on the behavior of photo-z algorithms. In this note we describe GASDRA, a new method for extracting the minimal signal to noise requirement, depending on the number of filters needed for preserving the filtered spectrum shape, and hence to make feasible the spectrum identification. The application of this requirement guaranties a determined precision in the spectrum measurement. Although it cannot be translated directly to absolute photometric redshift error, it does provide a method for comparing the relative precision achieved in the spectrum representation by different sets of filters. We foresee that this relative precision is close related to photo-z error. In addition, we can evaluate the impact in the exposure time of any filter partition set with respect to other. (Author) 11 refs.

GASDRA: Galaxy Spectrum Dynamic Range Analysis for Photometric Redshift Filter Partition Optimization

International Nuclear Information System (INIS)

Vicente, J. de; Sanchez, E.; Sevilla, I.; Castilla, J.; Ponce, R.; Sanchez, F. J.

2012-01-01

The photometric redshift is an active area of research. It is becoming the preferred method for redshift measurement above spectroscopy one for large surveys. In these surveys, the requirement in redshift precision is relaxed in benefit of obtaining the measurements of large number of galaxies. One of the more relevant decisions to be taken in the design of a photometric redshift experiment is the number of filters since it affects deeply to the precision and survey time. Currently, there is not a clear method for evaluating the impact in both precision and exposure time of a determined filter partition set and usually it is determined by detailed simulations on the behavior of photo-z algorithms. In this note we describe GASDRA, a new method for extracting the minimal signal to noise requirement, depending on the number of filters needed for preserving the filtered spectrum shape, and hence to make feasible the spectrum identification. The application of this requirement guaranties a determined precision in the spectrum measurement. Although it cannot be translated directly to absolute photometric redshift error, it does provide a method for comparing the relative precision achieved in the spectrum representation by different sets of filters. We foresee that this relative precision is close related to photo-z error. In addition, we can evaluate the impact in the exposure time of any filter partition set with respect to other. (Author) 11 refs.

A Differential Geometric Approach to Nonlinear Filtering: The Projection Filter

NARCIS (Netherlands)

Brigo, D.; Hanzon, B.; LeGland, F.

1998-01-01

This paper presents a new and systematic method of approximating exact nonlinear filters with finite dimensional filters, using the differential geometric approach to statistics. The projection filter is defined rigorously in the case of exponential families. A convenient exponential family is

Filter and Filter Bank Design for Image Texture Recognition

Energy Technology Data Exchange (ETDEWEB)

Randen, Trygve

1997-12-31

The relevance of this thesis to energy and environment lies in its application to remote sensing such as for instance sea floor mapping and seismic pattern recognition. The focus is on the design of two-dimensional filters for feature extraction, segmentation, and classification of digital images with textural content. The features are extracted by filtering with a linear filter and estimating the local energy in the filter response. The thesis gives a review covering broadly most previous approaches to texture feature extraction and continues with proposals of some new techniques. 143 refs., 59 figs., 7 tabs.

HEPA Filter Vulnerability Assessment

International Nuclear Information System (INIS)

GUSTAVSON, R.D.

2000-01-01

This assessment of High Efficiency Particulate Air (HEPA) filter vulnerability was requested by the USDOE Office of River Protection (ORP) to satisfy a DOE-HQ directive to evaluate the effect of filter degradation on the facility authorization basis assumptions. Within the scope of this assessment are ventilation system HEPA filters that are classified as Safety-Class (SC) or Safety-Significant (SS) components that perform an accident mitigation function. The objective of the assessment is to verify whether HEPA filters that perform a safety function during an accident are likely to perform as intended to limit release of hazardous or radioactive materials, considering factors that could degrade the filters. Filter degradation factors considered include aging, wetting of filters, exposure to high temperature, exposure to corrosive or reactive chemicals, and exposure to radiation. Screening and evaluation criteria were developed by a site-wide group of HVAC engineers and HEPA filter experts from published empirical data. For River Protection Project (RPP) filters, the only degradation factor that exceeded the screening threshold was for filter aging. Subsequent evaluation of the effect of filter aging on the filter strength was conducted, and the results were compared with required performance to meet the conditions assumed in the RPP Authorization Basis (AB). It was found that the reduction in filter strength due to aging does not affect the filter performance requirements as specified in the AB. A portion of the HEPA filter vulnerability assessment is being conducted by the ORP and is not part of the scope of this study. The ORP is conducting an assessment of the existing policies and programs relating to maintenance, testing, and change-out of HEPA filters used for SC/SS service. This document presents the results of a HEPA filter vulnerability assessment conducted for the River protection project as requested by the DOE Office of River Protection

Collection, processing and testing of bone, corneas, umbilical cord blood and haematopoietic stem cells by European Blood Alliance members

DEFF Research Database (Denmark)

Närhi, M; Natri, O; Desbois, I

2013-01-01

A questionnaire study was carried out in collaboration with the European Blood Alliance (EBA) Tissues and Cells (T&C) working group. The aim was to assess the level of involvement and commonality of processes on the procurement, testing and storage of bone, corneas, umbilical cord blood (UCB......) and haematopoietic stem cells (HSC) in order to identify different practices and to explore whether recommendations can be made for harmonization....

Potential for HEPA filter damage from water spray systems in filter plenums

Energy Technology Data Exchange (ETDEWEB)

Bergman, W. [Lawrence Livermore National Lab., CA (United States); Fretthold, J.K. [Rocky Flats Safe Sites of Colorado, Golden, CO (United States); Slawski, J.W. [Department of Energy, Germantown, MD (United States)

1997-08-01

The water spray systems in high efficiency particulate air (HEPA) filter plenums that are used in nearly all Department of Energy (DOE) facilities for protection against fire was designed under the assumption that the HEPA filters would not be damaged by the water sprays. The most likely scenario for filter damage involves filter plugging by the water spray, followed by the fan blowing out the filter medium. A number of controlled laboratory tests that were previously conducted in the late 1980s are reviewed in this paper to provide a technical basis for the potential HEPA filter damage by the water spray system in HEPA filter plenums. In addition to the laboratory tests, the scenario for BEPA filter damage during fires has also occurred in the field. A fire in a four-stage, BEPA filter plenum at Rocky Flats in 1980 caused the first three stages of BEPA filters to blow out of their housing and the fourth stage to severely bow. Details of this recently declassified fire are presented in this paper. Although these previous findings suggest serious potential problems exist with the current water spray system in filter plenums, additional studies are required to confirm unequivocally that DOE`s critical facilities are at risk. 22 refs., 15 figs.

Radio Frequency Sensing of Particulate Matter Accumulation on a Gasoline Particulate Filter

Energy Technology Data Exchange (ETDEWEB)

Parks, II, James E [ORNL; Prikhodko, Vitaly Y [ORNL; Sappok, Alex [Filter Sensing Technologies; Ragaller, Paul [Filter Sensing Technologies; Bromberg, L. [Massachusetts Institute of Technology (MIT)

2016-10-30

Filter Sensing Technology’s radio frequency (RF) sensor for particulate filter on-board diagnostics (OBD) was studied on a lean gasoline engine at the National Transportation Research Center (NTRC) at Oak Ridge National Laboratory (ORNL). The response of the RF sensor to particulate matter (PM) or “soot” accumulation on the gasoline particulate filter (GPF) installed in the engine exhaust was evaluated. In addition, end plugs of the GPF were purposely removed, and subsequent changes to the RF sensor measured soot loading on the GPF were characterized. Results from the study showed that the RF sensor can accurately measure soot accumulation on a GPF; furthermore, the predicted decreased soot accumulation due to plug removal was detected by the RF sensor. Overall, the studies were short and preliminary in nature; however, clearly, the RF sensor demonstrated the capability of measuring GPF soot loading at a level suitable for use in lean gasoline engine emission control OBD and control.

Uncertain Diagnosis of Fabry Disease in Patients with Neuropathic Pain, Angiokeratoma or Cornea Verticillata: Consensus on the Approach to Diagnosis and Follow-Up

NARCIS (Netherlands)

van der Tol, L.; Cassiman, David; Houge, Gunnar; Janssen, Mirian C.; Lachmann, Robin H.; Linthorst, Gabor E.; Ramaswami, Uma; Sommer, Claudia; Tøndel, Camilla; West, Michael L.; Weidemann, Frank; Wijburg, Frits A.; Svarstad, Einar; Hollak, Carla E. M.; Biegstraaten, Marieke

2014-01-01

Introduction: Individuals with neuropathic pain, angiokeratoma (AK) and/or cornea verticillata (CV) may be tested for Fabry disease (FD). Classical FD is characterised by a specific pattern of these features. When a patient presents with a non-specific pattern, the pathogenicity of a variant in the

Uncertain diagnosis of fabry disease in patients with neuropathic pain, angiokeratoma or cornea verticillata: consensus on the approach to diagnosis and follow-up

NARCIS (Netherlands)

Tol, L. van der; Cassiman, D.; Houge, G.; Janssen, M.C.; Lachmann, R.H.; Linthorst, G.E.; Ramaswami, U.; Sommer, C.; Tondel, C.; West, M.L.; Weidemann, F.; Wijburg, F.A.; Svarstad, E.; Hollak, C.E.M.; Biegstraaten, M.

2014-01-01

INTRODUCTION: Individuals with neuropathic pain, angiokeratoma (AK) and/or cornea verticillata (CV) may be tested for Fabry disease (FD). Classical FD is characterised by a specific pattern of these features. When a patient presents with a non-specific pattern, the pathogenicity of a variant in the

Beneficial effect of daidzin in dry eye rat model through the suppression of inflammation and oxidative stress in the cornea.

Science.gov (United States)

Xiao, Fan; Cui, Hua; Zhong, Xiao

2018-05-01

Present investigation evaluates the effect of daidzin in dry eye rat model through the suppression of inflammation and oxidative stress in the cornea. Briefly, electron spine resonance was used for the estimation of radical scavenging activity of daidzin and COX Fluorescent Activity Assay Kit was used for the estimation of PGS activity. Dry eye rat model was developed by removing the lacrimal gland and effect of daidzin was evaluated in dry eye rat model by estimating the fluorescein score, tear volume and expressions of heme oxigenase (HO-1), TNF α, Interlukin 6 (IL-6), matrix metallopeptidase 9 (MMP-9) and PGS-2. Result of the present study suggested that daidzin possess tyrosyl radical scavenging activity and thereby decreases the oxidative stress. Activity of PGS significantly increases in dry eye which was inhibited by daidzin treatment due to competitive inhibition of PGS. It also recovers the tear volume in dry eye rat model in which lacrimal gland was removed. Thus corneal erosion was improved by daidzin in dry eye rat model. Thus present study concludes that treatment with daidzin protects the cornea in dry eye rat model by suppression inflammation and oxidative stress.

Effects produced by different types of laser in cornea of Guinea pigs: Identification of a laser capable of producing superficial lesions without leaving scars.

Science.gov (United States)

Suárez, A C; Suárez, M F; Crim, N; Monti, R; Urrets-Zavalía, J A; Serra, H M

2015-10-01

Climatic droplets keratopathy (CDK) is closely associated with superficial corneal erosions and lack of protective mechanisms against the harmful effects of ultraviolet radiation (UVR) during a prolonged period of time. One of the difficulties in studying the pathogenic mechanisms involved in this human disease is the lack of an experimental animal model. In this paper, a study is conducted on the effects of 4 types of lasers at various powers and time conditions on the normal guinea pig corneas in order to select only one laser condition that reversibly injures the epithelium and superficial stroma, without leaving scarring. Damage was induced in the cornea of Guinea pigs using different powers and exposure times of 4 types of laser: argon, CO2, diode and Nd-Yag, and any injuries were evaluated by biomicroscopy (BM) and optical microscopy. Corneas from other normal animals were exposed to argon laser (350 mW, 0.3s, 50 μm of diameter), and the induced alterations were studied at different times using BM, optical coherence tomography (OCT) and transmission electron microscopy (TEM). Only argon laser at 350 mW, 0.3s, 50 μm of diameter produced epithelium and superficial stroma lesions. Some leukomas were observed by BM, and they disappeared by day 15. Corneal thickness measured by OCT decreased in the eyes treated with argon laser during the first week. Using TEM, different ultra structural alterations in corneal epithelium and stroma were observed during the early days, which disappeared by day 15. It was possible to develop reproducible corneal epithelium and anterior stroma injuries using Argon laser at 350 mW, 0.3s, 50 μm of diameter. In vivo and in vitro studies showed that injured corneas with these laser conditions did not leave irreversible microscopic or ultra structural alterations. This protocol of corneal erosion combined with exposure to UVR and partial deficiency of ascorbate in the diets of the animals for an extended period of time has been used in

Neutron Beam Filters

International Nuclear Information System (INIS)

Adib, M.

2011-01-01

The purpose of filters is to transmit neutrons with selected energy, while remove unwanted ones from the incident neutron beam. This reduces the background, and the number of spurious. The types of commonly used now-a-day neutron filters and their properties are discussed in the present work. There are three major types of neutron filters. The first type is filter of selective thermal neutron. It transmits the main reflected neutrons from a crystal monochromate, while reject the higher order contaminations accompanying the main one. Beams coming from the moderator always contain unwanted radiation like fast neutrons and gamma-rays which contribute to experimental background and to the biological hazard potential. Such filter type is called filter of whole thermal neutron spectrum. The third filter type is it transmits neutrons with energies in the resonance energy range (En . 1 KeV). The main idea of such neutron filter technique is the use of large quantities of a certain material which have the deep interference minima in its total neutron cross-section. By transmitting reactor neutrons through bulk layer of such material, one can obtain the quasimonochromatic neutron lines instead of white reactor spectrum.

Biofiltration of fishpond effluents and accumulation of N-compounds (phycobiliproteins and mycosporine-like amino acids) versus C-compounds (polysaccharides) in Hydropuntia cornea (Rhodophyta)

International Nuclear Information System (INIS)

Figueroa, Félix L.; Korbee, Nathalie; Abdala, Roberto; Jerez, Celia G.; López-de la Torre, Mayra; Güenaga, Leire; Larrubia, María A.; Gómez-Pinchetti, Juan L.

2012-01-01

The biofiltration capacity, biomass-yield and accumulation of N- and C-compounds of Hydropuntia cornea were analyzed. Algae were grown in different conditions for 28 d: outdoor and indoor, with or without fishpond effluents. N-uptake efficiency of these effluents was higher than 95% after 7 d both outdoors and indoors. N-enriched conditions reduced the extent of photoinhibition and increased the maximal quantum yield in H. cornea. The biomass-yield was higher in outdoor grown-algae after 7 d and decreased independently of the treatment after 28 d. N, acid polysaccharide (AP) and mycosporine-like amino acid (MAA)-yields decreased throughout the experiment in all conditions. The highest MAA-yield was observed in fishpond effluent outdoor-grown algae, indicating a positive effect of increased radiation on MAA accumulation. However, APs were higher under N-depleted conditions. The use of MAAs as UV-screening and antioxidants, and the use of AP as immunostimulants are discussed.

Biofiltration of fishpond effluents and accumulation of N-compounds (phycobiliproteins and mycosporine-like amino acids) versus C-compounds (polysaccharides) in Hydropuntia cornea (Rhodophyta).

Science.gov (United States)

Figueroa, Félix L; Korbee, Nathalie; Abdala, Roberto; Jerez, Celia G; López-de la Torre, Mayra; Güenaga, Leire; Larrubia, María A; Gómez-Pinchetti, Juan L

2012-02-01

The biofiltration capacity, biomass-yield and accumulation of N- and C-compounds of Hydropuntia cornea were analyzed. Algae were grown in different conditions for 28 d: outdoor and indoor, with or without fishpond effluents. N-uptake efficiency of these effluents was higher than 95% after 7 d both outdoors and indoors. N-enriched conditions reduced the extent of photoinhibition and increased the maximal quantum yield in H. cornea. The biomass-yield was higher in outdoor grown-algae after 7 d and decreased independently of the treatment after 28 d. N, acid polysaccharide (AP) and mycosporine-like amino acid (MAA)-yields decreased throughout the experiment in all conditions. The highest MAA-yield was observed in fishpond effluent outdoor-grown algae, indicating a positive effect of increased radiation on MAA accumulation. However, APs were higher under N-depleted conditions. The use of MAAs as UV-screening and antioxidants, and the use of AP as immunostimulants are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

Miniaturized dielectric waveguide filters

OpenAIRE

Sandhu, MY; Hunter, IC

2016-01-01

Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.

Concrete ensemble Kalman filters with rigorous catastrophic filter divergence.

Science.gov (United States)

Kelly, David; Majda, Andrew J; Tong, Xin T

2015-08-25

The ensemble Kalman filter and ensemble square root filters are data assimilation methods used to combine high-dimensional, nonlinear dynamical models with observed data. Ensemble methods are indispensable tools in science and engineering and have enjoyed great success in geophysical sciences, because they allow for computationally cheap low-ensemble-state approximation for extremely high-dimensional turbulent forecast models. From a theoretical perspective, the dynamical properties of these methods are poorly understood. One of the central mysteries is the numerical phenomenon known as catastrophic filter divergence, whereby ensemble-state estimates explode to machine infinity, despite the true state remaining in a bounded region. In this article we provide a breakthrough insight into the phenomenon, by introducing a simple and natural forecast model that transparently exhibits catastrophic filter divergence under all ensemble methods and a large set of initializations. For this model, catastrophic filter divergence is not an artifact of numerical instability, but rather a true dynamical property of the filter. The divergence is not only validated numerically but also proven rigorously. The model cleanly illustrates mechanisms that give rise to catastrophic divergence and confirms intuitive accounts of the phenomena given in past literature.

Hybrid Filter Membrane

Science.gov (United States)

Laicer, Castro; Rasimick, Brian; Green, Zachary

2012-01-01

Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

Mast Cell Activation Protects Cornea by Promoting Neutrophil Infiltration via Stimulating ICAM-1 and Vascular Dilation in Fungal Keratitis.

Science.gov (United States)

Xie, Yanting; Zhang, Hongmin; Liu, Susu; Chen, Guoming; He, Siyu; Li, Zhijie; Wang, Liya

2018-05-30

The role of mast cells (MCs) in fungal infection is largely unknown. This study was to explore a protective role and mechanism of MCs in fungal keratitis. Experimental fungal keratitis (FK) mouse model was developed. Mice untreated (UT) or receiving corneal wound without fungal infection (Mock) were used as controls. Large number of connective tissue MCs was found in normal mice. MC activation with degranulation was largely observed, and the percentage of degranulated/total cells was high in FK. Dilated limbal vasculature with increased permeability, as well as largely infiltrated neutrophils with stimulated ICAM-1 protein levels were observed in corneas of FK mice, when compared with Mock and UT mice. Interestingly, pretreatment with cromolyn sodium (Block) significantly blocked MC degranulation, dramatically suppressed vascular dilation and permeability, and markedly reduced neutrophil infiltration with lower ICAM-1 levels in FK mice at 6-24 hours. Furthermore, the Block mice manifested prolonged disease course, increased pathological damage, and vigorous fungus growth, with much higher corneal perforation rate than FK mice at 72 h. These findings reveal a novel phenomenon that MCs play a vital role in protecting cornea against fungal infection through degranulation that promotes neutrophil infiltration via stimulating ICAM-1 production and limbal vascular dilation and permeability.

A novel approach to achieving modular retrovirus clearance for a parvovirus filter.

Science.gov (United States)

Stuckey, Juliana; Strauss, Daniel; Venkiteshwaran, Adith; Gao, Jinxin; Luo, Wen; Quertinmont, Michelle; O'Donnell, Sean; Chen, Dayue

2014-01-01

Viral filtration is routinely incorporated into the downstream purification processes for the production of biologics produced in mammalian cell cultures (MCC) to remove potential viral contaminants. In recent years, the use of retentive filters designed for retaining parvovirus (~20 nm) has become an industry standard in a conscious effort to further improve product safety. Since retentive filters remove viruses primarily by the size exclusion mechanism, it is expected that filters designed for parvovirus removal can effectively clear larger viruses such as retroviruses (~100 nm). In an attempt to reduce the number of viral clearance studies, we have taken a novel approach to demonstrate the feasibility of claiming modular retrovirus clearance for Asahi Planova 20N filters. Porcine parvovirus (PPV) and xenotropic murine leukemia virus (XMuLV) were co-spiked into six different feedstreams and then subjected to laboratory scale Planova 20N filtration. Our results indicate that Planova 20N filters consistently retain retroviruses and no retrovirus has ever been detected in the filtrates even when significant PPV breakthrough is observed. Based on the data from multiple in-house viral validation studies and the results from the co-spiking experiments, we have successfully claimed a modular retrovirus clearance of greater than 6 log10 reduction factors (LRF) to support clinical trial applications in both USA and Europe. © 2013 American Institute of Chemical Engineers.

Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics.

Science.gov (United States)

Harput, Sevan; McLaughlan, James; Cowell, David M J; Freear, Steven

2014-11-01

Superharmonic imaging improves the spatial resolution by using the higher order harmonics generated in tissue. The superharmonic component is formed by combining the third, fourth, and fifth harmonics, which have low energy content and therefore poor SNR. This study uses coded excitation to increase the excitation energy. The SNR improvement is achieved on the receiver side by performing pulse compression with harmonic matched filters. The use of coded signals also introduces new filtering capabilities that are not possible with pulsed excitation. This is especially important when using wideband signals. For narrowband signals, the spectral boundaries of the harmonics are clearly separated and thus easy to filter; however, the available imaging bandwidth is underused. Wideband excitation is preferable for harmonic imaging applications to preserve axial resolution, but it generates spectrally overlapping harmonics that are not possible to filter in time and frequency domains. After pulse compression, this overlap increases the range side lobes, which appear as imaging artifacts and reduce the Bmode image quality. In this study, the isolation of higher order harmonics was achieved in another domain by using the fan chirp transform (FChT). To show the effect of excitation bandwidth in superharmonic imaging, measurements were performed by using linear frequency modulated chirp excitation with varying bandwidths of 10% to 50%. Superharmonic imaging was performed on a wire phantom using a wideband chirp excitation. Results were presented with and without applying the FChT filtering technique by comparing the spatial resolution and side lobe levels. Wideband excitation signals achieved a better resolution as expected, however range side lobes as high as -23 dB were observed for the superharmonic component of chirp excitation with 50% fractional bandwidth. The proposed filtering technique achieved >50 dB range side lobe suppression and improved the image quality without

University students' knowledge of corneal donation and willingness to donate corneas in the occupied Palestinian territory: a cross-sectional study.

Science.gov (United States)

Al-Labadi, Liana; Gammoh, Yazan; Shehada, Reham; Shahin, Reem; Jbarah, Walaa; Amro, Madleen; Athamny, Hanan

2018-02-21

Access to corneal transplantation is limited worldwide because of poor knowledge. Ethical, religious, and cultural barriers contribute to low rates of corneal donation. In the occupied Palestinian territory, limited information is available on factors affecting corneal donation. The aim of this study was to assess the knowledge and willingness towards corneal donation in Palestinian students. This cross-sectional study included university students selected through convenience sampling in Nablus in the summer of 2016. The sample size was determined using the sample formulae and a 15% non-response rate. All students registered in obligatory courses were included in the study after verbal consent. Each participant was given a self-administered questionnaire consisting of 14 questions to assess knowledge, awareness, and willingness toward corneal donation. Frequencies were used for descriptive analysis, and associations were determined using multivariate analysis and χ 2 test, with a p value of less than 0·05 considered significant. Of the 634 students completing the questionnaire, 411 (65%) were women, 614 (97%) were Muslims, and 155 (25%) were health or medical students. 592 (93%) respondents were unaware of eye bank availability, and 407 (69%; p=0.002) of these respondents did not show willingness towards corneal donation. 431 (67%) respondents were aware of a lack in corneal donation, but 274 (64%; p=0·01) of these respondents did not show willingness towards corneal donation. 429 (68%) respondents were not willing to donate their corneas, the most common reasons being disapproval by family members and poor awareness. We found no association between sociodemographic factors and willingness was determined. Palestinian students are aware of the lack of local cornea donation but are unwilling to donate their corneas. The study results are not representative of the entire population because of the homogeneous nature of the sample. Large efforts are needed locally to

Quantitative & qualitative analysis of endothelial cells of donor cornea before & after penetrating keratoplasty in different pathological conditions

Directory of Open Access Journals (Sweden)

Aruna K.R. Gupta

2016-01-01

Full Text Available Background & objectives: Endothelial cells of the donor cornea are known to be affected quantitatively and qualitatively in different pathological conditions after penetrating keratoplasty (PK and this has direct effect on the clarity of vision obtained after PK. This study was undertaken to analyze the qualitative and quantitative changes in donor endothelial cells before and after PK in different pathological conditions. Methods: A prospective investigational analysis of 100 consecutive donor corneas used for penetrating keratoplasty between June 2006 and June 2008, was conducted. The patients were evaluated on the first day, at the end of first week, first month, third and six months and one year. Results: A decrease was observed in endothelial cell count in all pathological conditions. After one year of follow up the loss was 33.1 per cent in corneal opacity, 45.9 per cent in acute infective keratitis (AIK, 58.5 per cent in regrafts, 28.5 per cent in pseudophakic bullous keratopathy (PBK, 37 per cent in descemetocele, 27 per cent in keratoconus and 35.5 per cent in aphakic bullous keratopathy (ABK cases. Interpretation & conclusions: The endothelial cell loss was highest in regraft cases which was significant (P<0.05, while the least endothelial cell loss was seen in keratoconus cases. The cell loss was associated with increase in coefficient of variation (CV, i.e. polymegathism and pleomorphism. Inspite of this polymegathism and pleomorphism, the clarity of the graft was maintained.

Sampled data CT system including analog filter and compensating digital filter

International Nuclear Information System (INIS)

Glover, G. H.; DallaPiazza, D. G.; Pelc, N. J.

1985-01-01

A CT scanner in which the amount of x-ray information acquired per unit time is substantially increased by using a continuous-on x-ray source and a sampled data system with the detector. An analog filter is used in the sampling system for band limiting the detector signal below the highest frequency of interest, but is a practically realizable filter and is therefore non-ideal. A digital filter is applied to the detector data after digitization to compensate for the characteristics of the analog filter, and to provide an overall filter characteristic more nearly like the ideal

Quick-change filter cartridge

Science.gov (United States)

Rodgers, John C.; McFarland, Andrew R.; Ortiz, Carlos A.

1995-01-01

A quick-change filter cartridge. In sampling systems for measurement of airborne materials, a filter element is introduced into the sampled airstream such that the aerosol constituents are removed and deposited on the filter. Fragile sampling media often require support in order to prevent rupture during sampling, and careful mounting and sealing to prevent misalignment, tearing, or creasing which would allow the sampled air to bypass the filter. Additionally, handling of filter elements may introduce cross-contamination or exposure of operators to toxic materials. Moreover, it is desirable to enable the preloading of filter media into quick-change cartridges in clean laboratory environments, thereby simplifying and expediting the filter-changing process in the field. The quick-change filter cartridge of the present invention permits the application of a variety of filter media in many types of instruments and may also be used in automated systems. The cartridge includes a base through which a vacuum can be applied to draw air through the filter medium which is located on a porous filter support and held there by means of a cap which forms an airtight seal with the base. The base is also adapted for receiving absorbing media so that both particulates and gas-phase samples may be trapped for investigation, the latter downstream of the aerosol filter.

VIP and VIP gene silencing modulation of differentiation marker N-cadherin and cell shape of corneal endothelium in human corneas ex vivo.

Science.gov (United States)

Koh, Shay-Whey M; Chandrasekara, Krish; Abbondandolo, Cara J; Coll, Timothy J; Rutzen, Allan R

2008-08-01

Vasoactive intestinal peptide (VIP) is expressed by corneal endothelial (CE) cells and is present in the aqueous humor, which bathes CE cells in vivo. This study demonstrated the role of CE cell VIP in maintaining the expression level of a CE differentiation marker, N-cadherin, and the hexagonal cell shape. To determine the most effective VIP concentration, bovine corneoscleral explants were treated with 0 (control) and 10(-12) to 10(-6) M VIP. Paired human corneas (nine donors) from an eye bank were used as control; the other corneas were treated with VIP. To silence endogenous VIP, paired fresh human donor corneas (from seven cadavers) were transduced with VIP shRNA or the control lentiviral particles and then bisected/quartered for quantitative analysis by semiquantitative RT-PCR (for mRNA) and Western blot analysis/immunocytochemistry (for protein), whereas alizarin red S staining revealed CE cell shape. VIP concentration dependently increased bovine CE cell N-cadherin mRNA levels, with the maximal effect observed between 10(-10) (1.47 +/- 0.06-fold; P = 0.002) and 10(-8) M VIP (1.48 +/- 0.18-fold; P = 0.012). VIP (10(-8) M) treatment increased N-cadherin protein levels in bovine and human CE cells to 1.98 +/- 0.28-fold (P = 0.005) and 1.17 +/- 0.10 (range, 0.91-1.87)-fold (P = 0.050) of their respective controls. VIP antagonist (SN)VIPhyb diminished the VIP effect. VIP silencing resulted in deterioration of the hexagonal cell shape and decreased levels of VIP protein and mRNA, N-cadherin (but not connexin-43) mRNA and protein, and the antiapoptotic Bcl-2 protein. Through its autocrine VIP, CE cells play an active role in maintaining the differentiated state and suppressing apoptosis in the corneal endothelium in situ.

Improved Kalman Filter-Based Speech Enhancement with Perceptual Post-Filtering

Institute of Scientific and Technical Information of China (English)

WEIJianqiang; DULimin; YANZhaoli; ZENGHui

2004-01-01

In this paper, a Kalman filter-based speech enhancement algorithm with some improvements of previous work is presented. A new technique based on spectral subtraction is used for separation speech and noise characteristics from noisy speech and for the computation of speech and noise Autoregressive (AR) parameters. In order to obtain a Kalman filter output with high audible quality, a perceptual post-filter is placed at the output of the Kalman filter to smooth the enhanced speech spectra.Extensive experiments indicate that this newly proposed method works well.

Method for cleaning the filter pockets of dust gas filter systems

Energy Technology Data Exchange (ETDEWEB)

Margraf, A

1975-05-07

The invention deals with a method to clean filter pockets filled with dust gas. By a periodic to and fro air jet attached to a scavenging blower, a pulsed fluttering movement of the filter surface is obtained which releases the outer layers of dust. The charging of the filter pockets with scavenging air to clean the filter material can be carried out immediately on the pulsed admission with suitable time control.

Mass Conservation and Positivity Preservation with Ensemble-type Kalman Filter Algorithms

Science.gov (United States)

Janjic, Tijana; McLaughlin, Dennis B.; Cohn, Stephen E.; Verlaan, Martin

2013-01-01

Maintaining conservative physical laws numerically has long been recognized as being important in the development of numerical weather prediction (NWP) models. In the broader context of data assimilation, concerted efforts to maintain conservation laws numerically and to understand the significance of doing so have begun only recently. In order to enforce physically based conservation laws of total mass and positivity in the ensemble Kalman filter, we incorporate constraints to ensure that the filter ensemble members and the ensemble mean conserve mass and remain nonnegative through measurement updates. We show that the analysis steps of ensemble transform Kalman filter (ETKF) algorithm and ensemble Kalman filter algorithm (EnKF) can conserve the mass integral, but do not preserve positivity. Further, if localization is applied or if negative values are simply set to zero, then the total mass is not conserved either. In order to ensure mass conservation, a projection matrix that corrects for localization effects is constructed. In order to maintain both mass conservation and positivity preservation through the analysis step, we construct a data assimilation algorithms based on quadratic programming and ensemble Kalman filtering. Mass and positivity are both preserved by formulating the filter update as a set of quadratic programming problems that incorporate constraints. Some simple numerical experiments indicate that this approach can have a significant positive impact on the posterior ensemble distribution, giving results that are more physically plausible both for individual ensemble members and for the ensemble mean. The results show clear improvements in both analyses and forecasts, particularly in the presence of localized features. Behavior of the algorithm is also tested in presence of model error.

A Digital Image Denoising Algorithm Based on Gaussian Filtering and Bilateral Filtering

Directory of Open Access Journals (Sweden)

Piao Weiying

2018-01-01

Full Text Available Bilateral filtering has been applied in the area of digital image processing widely, but in the high gradient region of the image, bilateral filtering may generate staircase effect. Bilateral filtering can be regarded as one particular form of local mode filtering, according to above analysis, an mixed image de-noising algorithm is proposed based on Gaussian filter and bilateral filtering. First of all, it uses Gaussian filter to filtrate the noise image and get the reference image, then to take both the reference image and noise image as the input for range kernel function of bilateral filter. The reference image can provide the image’s low frequency information, and noise image can provide image’s high frequency information. Through the competitive experiment on both the method in this paper and traditional bilateral filtering, the experimental result showed that the mixed de-noising algorithm can effectively overcome staircase effect, and the filtrated image was more smooth, its textural features was also more close to the original image, and it can achieve higher PSNR value, but the amount of calculation of above two algorithms are basically the same.

Cellulose Degradation by Cellulose-Clearing and Non-Cellulose-Clearing Brown-Rot Fungi

OpenAIRE

Highley, Terry L.

1980-01-01

Cellulose degradation by four cellulose-clearing brown-rot fungi in the Coniophoraceae—Coniophora prasinoides, C. puteana, Leucogyrophana arizonica, and L. olivascens—is compared with that of a non-cellulose-clearing brown-rot fungus, Poria placenta. The cellulose- and the non-cellulose-clearing brown-rot fungi apparently employ similar mechanisms to depolymerize cellulose; most likely a nonenzymatic mechanism is involved.

Filtering Photogrammetric Point Clouds Using Standard LIDAR Filters Towards DTM Generation

Science.gov (United States)

Zhang, Z.; Gerke, M.; Vosselman, G.; Yang, M. Y.

2018-05-01

Digital Terrain Models (DTMs) can be generated from point clouds acquired by laser scanning or photogrammetric dense matching. During the last two decades, much effort has been paid to developing robust filtering algorithms for the airborne laser scanning (ALS) data. With the point cloud quality from dense image matching (DIM) getting better and better, the research question that arises is whether those standard Lidar filters can be used to filter photogrammetric point clouds as well. Experiments are implemented to filter two dense matching point clouds with different noise levels. Results show that the standard Lidar filter is robust to random noise. However, artefacts and blunders in the DIM points often appear due to low contrast or poor texture in the images. Filtering will be erroneous in these locations. Filtering the DIM points pre-processed by a ranking filter will bring higher Type II error (i.e. non-ground points actually labelled as ground points) but much lower Type I error (i.e. bare ground points labelled as non-ground points). Finally, the potential DTM accuracy that can be achieved by DIM points is evaluated. Two DIM point clouds derived by Pix4Dmapper and SURE are compared. On grassland dense matching generates points higher than the true terrain surface, which will result in incorrectly elevated DTMs. The application of the ranking filter leads to a reduced bias in the DTM height, but a slightly increased noise level.

Bias aware Kalman filters

DEFF Research Database (Denmark)

Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

2006-01-01

This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model state....... The colored noise filter formulation is extended to correct both time correlated and uncorrelated model error components. A more stable version of the separate filter without feedback is presented. The filters are implemented in an ensemble framework using Latin hypercube sampling. The techniques...... are illustrated on a simple one-dimensional groundwater problem. The results show that the presented filters outperform the standard Kalman filter and that the implementations with bias feedback work in more general conditions than the implementations without feedback. 2005 Elsevier Ltd. All rights reserved....

Study of different filters

International Nuclear Information System (INIS)

Cochinal, R.; Rouby, R.

1959-01-01

This note first contains a terminology related to filters and to their operation, and then proposes an overview of general characteristics of filters such as load loss with respect to gas rate, efficiency, and clogging with respect to filter pollution. It also indicates standard aerosols which are generally used, how they are dosed, and how efficiency is determined with a standard aerosol. Then, after a presentation of the filtration principle, this note reports the study of several filters: glass wool, filter papers provided by different companies, Teflon foam, English filters, Teflon wool, sintered Teflonite, quartz wool, polyvinyl chloride foam, synthetic filter, sintered bronze. The third part reports the study of some aerosol and dust separators

Numerical Study on Self-Cleaning Canister Filter With Add-On Filter Cap

Directory of Open Access Journals (Sweden)

Mohammed Akmal Nizam

2017-01-01

Full Text Available Filtration in a turbo machinery system such as a gas turbine will ensure that the air entering the inlet is free from contaminants that could bring damage to the main system. Self-cleaning filter systems for gas turbines are designed for continuously efficient flow filtration. A good filter would be able to maintain its effectiveness over a longer time period, prolonging the duration between filter replacements and providing lower pressure drop over its operating lifetime. With this goal in mind, the current study is focused on the difference in pressure loss of the benchmark Salutary Avenue Self-cleaning filter in comparison to a new design with an add-on filter cap. Geometry for the add-on filter cap will be based from Salutary Avenue Manufacturing Sdn.Bhd. SOLIDWORKS software was used to model the geometry of the filter, while simulation analysis on the flow through the filter was done using Computational Fluid Dynamic (CFD software. The simulations are based on a low velocity condition, in which the parameter for the inlet velocity are set at 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s respectively. From the simulation data obtained for the inlet velocities considered, the pressure drop reduction of the modified filter compared to the benchmark was found to be between 7.59% and 30.18%. All in all, the modification of the filter cap produced a lower pressure drop in comparison with the benchmark filter; an improvement of 27.02% for the total pressure drop was obtained.

Laboratory for filter testing

Energy Technology Data Exchange (ETDEWEB)

Paluch, W.

1987-07-01

Filters used for mine draining in brown coal surface mines are tested by the Mine Draining Department of Poltegor. Laboratory tests of new types of filters developed by Poltegor are analyzed. Two types of tests are used: tests of scale filter models and tests of experimental units of new filters. Design and operation of the test stands used for testing mechanical properties and hydraulic properties of filters for coal mines are described: dimensions, pressure fluctuations, hydraulic equipment. Examples of testing large-diameter filters for brown coal mines are discussed.

Conhecimento de estudantes de medicina sobre o processo de doação de córneas The knowledge of medical students about cornea donation

Directory of Open Access Journals (Sweden)

Rodrigo França de Espíndola

2007-08-01

Full Text Available OBJETIVO: Avaliar o conhecimento de estudantes de medicina sobre o processo de doação de córneas, comparando-o entre aqueles que já cursaram a disciplina de Oftalmologia com os demais. MÉTODOS: Foi aplicado um questionário a estudantes de medicina do interior de São Paulo, contendo dados como: idade, sexo, ano de graduação e 10 perguntas de múltipla escolha sobre o tema. As questões abordaram o limite de idade para doação, contra-indicações para o transplante, tempo para retirada das córneas, dentre outras. Foi comparado o conhecimento (% de acertos entre aqueles que haviam cursado a disciplina de Oftalmologia (Grupo A com os demais (Grupo B. RESULTADOS: Foram entrevistados 402 estudantes. Destes, 140 eram do grupo A e 262 do grupo B. Não houve diferença estatisticamente significante entre os dois grupos (p=0,8328. CONCLUSÃO: O conhecimento sobre o processo de doação de córneas mostrou-se insuficiente entre os alunos entrevistados, mesmo para aqueles que haviam cursado a disciplina de Oftalmologia, apontando a necessidade de aperfeiçoamento do conhecimento divulgado nas escolas médicas.PURPOSE: To compare knowledge of medical students about the cornea donation process among those who already studied Ophthalmology and the others. METHODOS: A questionnaire containing data as: age, sex, graduation year, and 10 multiple-choice questions about the subject was applied to medical students from the interior of São Paulo state, Brazil. The questions were: age for donation, contraindication for transplants, the time limit to remove the cornea, among others. The knowledge regarding cornea donation was compared between the two groups: students who already studied Ophthalmology (Group A and the others (Group B. RESULTS: The study group was composed of 402 students, of whom 140 were of group A and 262 of group B. Knowledge between the two groups was different, but not statistically significant (p=0.8328. CONCLUSION: Knowledge about

Simulasi Filter Pasif Dan Perbandingan Unjuk Kerjanya Dengan Filter Aktif Dan Filter Aktif Hibrid Dalam Meredam Harmonisa Pada Induction Furnace

OpenAIRE

Tanoto, Yusak; Limantara, Limboto; Khandy Lestanto, Khristian

2005-01-01

This paper describe about simulation of Passive Filter in analysis to reduce harmonics that happened in a load such as vacuum casting induction furnace 9 kW, 13.8 kVA, 200V, 3 Ph, 50/60 Hz, also gives comparison with Hybrid Active Filter and Active Filter which made satisfaction result on the previous research. The best result achieved on the use of Hybrid Active Filter on %ITHD for 4.27 % and %VTHD for 3.83%, while Active Filter gave on %ITHD for 5.14 % and %VTHD for 3.82%. There ...

Enucleaton of the right eye due to large choroidal melanoma with simultaneous penetrating cornea transplantation from OD to OS (Case report).

OpenAIRE

E. A. Korchuganova; A. Yu. Slonimskiy,; O. Yu. Yatsenko; M. Yu. Lerner

2013-01-01

There is presentation case report of 75‑year old woman with choroidal melanoma (T3N0M0) on the right eye and failed graft on the left pseudophakic eye with far advanced glaucoma and ARMD. No treatment was given to the leading eye with VA 0,2. VA of OS = 1 / ∞ pr.l.certa; PKP OS in 2008 for pseudophakic bullous keratopathy on the eye with far advanced glaucoma. IOP was normal after previous filtering surgery. After PKP VA = 0,04; clear graft during 2 years; then gradually opacification and vas...

Rotation speed measurement for turbine governor: torsion filtering by using Kalman filter

International Nuclear Information System (INIS)

Houry, M.P.; Bourles, H.

1996-01-01

The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this speed is a problem of a great practical importance for turbine governor. A good filtering of this speed must meet two requirements: it must cut frequencies of the shaft torsion oscillation and it must not reduce or delay the signal in the pass-band, i.e. at lower frequencies. At Electricite de France, the speed measure is used to set in motion the fast valving system as quickly as possible, after a short circuit close to the unit or rather an islanding. It is difficult to satisfy these two requirements by using conventional filtering methods. The standard solution consists in a first order filter: at Electricite de France, its time constant is equal to 80 ms. We have decided to improve this filtering by designing a new filter which cuts the frequencies of the shaft torsion oscillation without reducing the bandwidth to the speed measure. If one uses conventional methods to obtain a band stop filter, it is easy to obtain the desired magnitude but not a phase near zero in the whole pass-band. Therefore, we have chosen to design the filter by using Kalman'a theory. The measurement noise is modeled as a colored one, generated by a very lightly damped system driven by a while noise. The resulting Kalman filter is an effective band stop filter, whose phase nicely remains near zero in the whole pass-band. The digital simulations we made and the tests we carried out with the Electricite de France Micro Network laboratory show the advantages of the rotation speed filter we designed using Kalman's theory. With the proposed filter, the speed measure filtering is better in terms of reduction and phase shift. the result is that there are less untimely solicitations of the fast valving system. Consequently, this device improves the power systems stability by minimizing the risks of deep perturbations due to a temporary lack of generation and the risks of under-speed loss

The dry filter method for passive filtered venting of the containment

International Nuclear Information System (INIS)

Freis, Daniel; Tietsch, Wolfgang; Obenland, Ralf; Kroes, Bert; Martinsteg, Hans

2013-01-01

Filtered Venting is a mitigative emergency measure to protect the containment from pressure failure in case of a severe accident. Filtered vent systems which are based on the Dry Filter Method (DFM) are proven technology, work completely passive, meet all functional requirements and show excellent performance with respect to filter efficiency. With such a system the release of radioactive fission products to the environment can be effectively minimized. Short and long term land contaminations can be avoided. (orig.)

Generalized Selection Weighted Vector Filters

Directory of Open Access Journals (Sweden)

Rastislav Lukac

2004-09-01

Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.

Rotation speed measurement for turbine governor: torsion filtering by using Kalman filter

International Nuclear Information System (INIS)

Houry, M.P.; Bourles, H.

1995-11-01

The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this sped a problem of a great practical importance for turbine governor. A good filtering of this speed must meet two requirements: it must cut frequencies of the shaft torsion oscillation and it must not reduce or delay the signal in the pass-band. i.e. at lower frequencies. At Electricite de France, the speed measure is used to set in motion the fast valving system as quickly as possible, after a short circuit close to the unit (to contribute to the stability) or after an islanding (to quickly reach a balance with the house load). It is difficult to satisfy these two requirements by using conventional filtering methods. The standard solution consists in a first order filter: at Electricite de France, its time constant is equal to 80 ms; We have decided to improve this filtering by designing a new filter which cuts the frequencies of the shaft torsion oscillation without reducing the bandwidth of the speed measure. If one uses conventional methods to obtain a band-stop filter (for instance a Butterworth, a Chebyshev or an elliptic band-stop filter),it is easy to obtain the desired magnitude but not a phase near zero in the whole pass-band. Therefore, we have chosen to design the filter by using Kalman's theory. The measurement noise is modeled as a colored one, generated by a very lightly damped system driven by a white noise. The resulting Kalman filter is an effective band-stop filter, whose phase nicely remains near zero in the whole pass-band. (authors). 13 refs., 12 figs

Optimization of filter loading

International Nuclear Information System (INIS)

Turney, J.H.; Gardiner, D.E.; Sacramento Municipal Utility District, Herald, CA)

1985-01-01

The introduction of 10 CFR Part 61 has created potential difficulties in the disposal of spent cartridge filters. When this report was prepared, Rancho Seco had no method of packaging and disposing of class B or C filters. This work examined methods to minimize the total operating cost of cartridge filters while maintaining them below the class A limit. It was found that by encapsulating filters in cement the filter operating costs could be minimized

Suitability of adsorption isotherms for predicting the retention capacity of active slag filters removing phosphorus from wastewater.

Science.gov (United States)

Pratt, C; Shilton, A

2009-01-01

Active slag filters are an emerging technology for removing phosphorus (P) from wastewater. A number of researchers have suggested that adsorption isotherms are a useful tool for predicting P retention capacity. However, to date the appropriateness of using isotherms for slag filter design remains unverified due to the absence of benchmark data from a full-scale, field filter operated to exhaustion. This investigation compared the isotherm-predicted P retention capacity of a melter slag with the P adsorption capacity determined from a full-scale, melter slag filter which had reached exhaustion after five years of successfully removing P from waste stabilization pond effluent. Results from the standard laboratory batch test showed that P adsorption correlated more strongly with the Freundlich Isotherm (R(2)=0.97, Pretention capacity of 0.014 gP/kg slag; markedly lower than the 1.23 gP/kg slag adsorbed by the field filter. Clearly, the result generated by the isotherm bears no resemblance to actual field capacity. Scanning electron microscopy analysis revealed porous, reactive secondary minerals on the slag granule surfaces from the field filter which were likely created by weathering. This slow weathering effect, which generates substantial new adsorption sites, is not accounted for by adsorption isotherms rendering them ineffective in slag filter design.

[Humidification assessment of four heat and moisture exchanger filters according to ISO 9360: 2000 standard].

Science.gov (United States)

Lannoy, D; Décaudin, B; Resibois, J-P; Barrier, F; Wierre, L; Horrent, S; Batt, C; Moulront, S; Odou, P

2008-02-01

This work consisted of the assessment of humidification parameters and flow resistance for different heat and moisture exchanger filters (HMEF) used in intensive care unit. Four electrostatic HMEF were assessed: Hygrobac S (Tyco); Humidvent compact S (Teleflex); Hygrovent S/HME (Medisize-Dräger); Clear-Therm+HMEF (Intersurgical). Humidification parameters (loss of water weight, average absolute moisture [AAM], absolute variation of moisture) have been evaluated on a bench-test in conformity with the ISO 9360: 2000 standard, for 24h with the following ventilatory settings: tidal volume at 500 ml, respiratory rate at 15 c/min, and inspiration/expiration ratio at 1:1. The flow resistance of HMEFs assessed using the pressure drop method was measured before and after 24h of humidification for three increasing air flows of 30, 60, and 90 l/min. All the HMEFs allowed satisfactory level of humidification exceeding 30 mgH(2)O/l. The less powerful remained the Clear-Therm. Concerning HMEFs flow resistance, results showed a pressure drop slightly more important for the Hygrobac S filter as compared with other filters. This test showed differences between the HMEFs for both humidification and resistance parameters. When compared to the new version of the standards, HMEFs demonstrated their reliability. However, evolution of humidification and flow resistance characteristics over 24h showed a structural degradation of HMEFs, limiting their use over a longer period.

Beneficial effect of daidzin in dry eye rat model through the suppression of inflammation and oxidative stress in the cornea

Directory of Open Access Journals (Sweden)

Fan Xiao

2018-05-01

Full Text Available Present investigation evaluates the effect of daidzin in dry eye rat model through the suppression of inflammation and oxidative stress in the cornea. Briefly, electron spine resonance was used for the estimation of radical scavenging activity of daidzin and COX Fluorescent Activity Assay Kit was used for the estimation of PGS activity. Dry eye rat model was developed by removing the lacrimal gland and effect of daidzin was evaluated in dry eye rat model by estimating the fluorescein score, tear volume and expressions of heme oxigenase (HO-1, TNF α, Interlukin 6 (IL-6, matrix metallopeptidase 9 (MMP-9 and PGS-2. Result of the present study suggested that daidzin possess tyrosyl radical scavenging activity and thereby decreases the oxidative stress. Activity of PGS significantly increases in dry eye which was inhibited by daidzin treatment due to competitive inhibition of PGS. It also recovers the tear volume in dry eye rat model in which lacrimal gland was removed. Thus corneal erosion was improved by daidzin in dry eye rat model. Thus present study concludes that treatment with daidzin protects the cornea in dry eye rat model by suppression inflammation and oxidative stress. Keywords: Daidzin, Dry eye, Radical scavenging activity, Inflammation

76 FR 47529 - Customer Clearing Documentation and Timing of Acceptance for Clearing; Correction

Science.gov (United States)

2011-08-05

... COMMODITY FUTURES TRADING COMMISSION 17 CFR Parts 1, 23, and 39 RIN 3038-AD51 Customer Clearing Documentation and Timing of Acceptance for Clearing; Correction AGENCY: Commodity Futures Trading Commission... published in the Federal Register of August 1, 2011, regarding Customer Clearing Documentation and Timing of...

Optical coherence elastography assesses tissue modifications in laser reshaping of cornea and cartilages

Science.gov (United States)

Zaitsev, V. Y.; Matveyev, A. L.; Matveev, L. A.; Gelikonov, G. V.; Omelchenko, A. I.; Shabanov, D. V.; Sovetsky, A. A.; Baum, O. I.; Vitkin, A.; Sobol, E. N.

2018-02-01

Non-surgical thermo-mechanical reshaping of avascular collagenous tissues (cartilages and cornea) using moderate heating by IR-laser irradiation is an emerging technology that can find important applications in visioncorrection problems and preparation of cartilaginous implants in otolaryngology. To estimate both transient interframe strains and cumulative resultant strains produced by the laser irradiation of the tissue we use and improved version of strain mapping developed in our previous work related to compressional phase-sensitive optical coherence tomography. To reveal microstructural changes in the tissue regions where irradiation-produced strains do not disappear after temperature equilibration, we apply compressional optical coherence elastography in order to visualize the resultant variations in the tissue stiffness. The so-found regions of the stiffness reduction are attributed to formation of microscopic pores, existence of which agree with independent data obtained using methods of high-resolution microscopy.

Retrievable Vena Cava Filters in Major Trauma Patients: Prevalence of Thrombus Within the Filter

International Nuclear Information System (INIS)

Mahrer, Arie; Zippel, Douglas; Garniek, Alexander; Golan, Gil; Bensaid, Paul; Simon, Daniel; Rimon, Uri

2008-01-01

The purpose of this study was to report the prevalence of thrombus within a retrievable vena cava filter inserted prophylactically in major trauma patients referred for filter extraction. Between November 2002 and August 2005, 80 retrievable inferior vena cava filters (68 Optease and 12 Gunther-Tulip) were inserted into critically injured trauma patients (mean injury severity score 33.5). The filters were inserted within 1 to 6 (mean 2) days of injury. Thirty-seven patients were referred for filter removal (32 with Optease and 5 with Gunther-Tulip). The indwelling time was 7 to 22 (mean 13) days. All patients underwent inferior vena cavography prior to filter removal. There were no insertion-related complications and all filters were successfully deployed. Forty-three (54%) of the 80 patients were not referred for filter removal, as these patients continued to have contraindications to anticoagulation. Thirty-seven patients (46%) were referred for filter removal. In eight of them (22%) a large thrombus was seen within the filters and they were left in place, all with the Optease device. The other 29 filters (36%) were removed uneventfully.We conclude that the relatively high prevalence of intrafilter thrombi with the Optease filter may be explained by either spontaneous thrombus formation or captured emboli.

Physical characteristics of the paper filter and low cafestol content filter coffee brews.

Science.gov (United States)

Rendón, Mery Yovana; Dos Santos Scholz, Maria Brígida; Bragagnolo, Neura

2018-06-01

The results found in the literature concerning the effect of consuming filter coffee brews on increasing the blood cholesterol levels due to the presence of diterpenes, are divergent. Thus the present research evaluated the diterpene (cafestol and kahweol) concentrations in filter coffee brews prepared with paper filters of different sizes, colors and origins (Brazil, Japan, The United States of America, Germany, France and the Netherlands), with and without micro perforations. This is the first study that reports the physical characteristics of paper filter and its importance to obtain filter coffee brew with low cafestol content. Thus, a sample of Catuai cultivar coffee with high cafestol content was roasted to a medium-light degree and used to prepare the brews in a 1:10 ratio (coffee powder to water). The diterpenes were extracted by direct saponification and quantified and identified by HPLC-DAD-MS/MS. The paper filters were physically characterized by measuring their grammage, and the fat permeation rate calculated in order to better understand the differences between the filters which allow one to obtain higher or lower diterpene contents. The cafestol and kahweol concentrations in the brews varied from 1.62 to 2.98 mg/L and from 0.73 to 1.96 mg/L, respectively. The highest cafestol and kahweol concentrations were obtained using paper filters with micro perforations, considering similar sized paper filters. The paper filters showed high fat permeability and grammages between 50.46 and 67.48 g/m 2 . The diterpene retention capacities of the filters produced in the different countries were similar. The results showed that the porosity of the paper filter and the particle size of the ground roasted coffee were determinant factors in obtaining filter coffee brews with lower cafestol contents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sustained Subconjunctival Delivery of Infliximab Protects the Cornea and Retina Following Alkali Burn to the Eye.

Science.gov (United States)

Zhou, Chengxin; Robert, Marie-Claude; Kapoulea, Vassiliki; Lei, Fengyang; Stagner, Anna M; Jakobiec, Frederick A; Dohlman, Claes H; Paschalis, Eleftherios I

2017-01-01

Tumor necrosis factor (TNF)-α is upregulated in eyes following corneal alkali injury and contributes to corneal and also retinal damage. Prompt TNF-α inhibition by systemic infliximab ameliorates retinal damage and improves corneal wound healing. However, systemic administration of TNF-α inhibitors carries risk of significant complications, whereas topical eye-drop delivery is hindered by poor ocular bioavailability and the need for patient adherence. This study investigates the efficacy of subconjunctival delivery of TNF-α antibodies using a polymer-based drug delivery system (DDS). The drug delivery system was prepared using porous polydimethylsiloxane/polyvinyl alcohol composite fabrication and loaded with 85 μg of infliximab. Six Dutch-belted pigmented rabbits received ocular alkali burn with NaOH. Immediately after the burn, subconjunctival implantation of anti-TNF-α DDS was performed in three rabbits while another three received sham DDS (without antibody). Rabbits were followed with photography for 3 months. After 3 months, the device was found to be well tolerated by the host and the eyes exhibited less corneal damage as compared to eyes implanted with a sham DDS without drug. The low dose treatment suppressed CD45 and TNF-α expression in the burned cornea and inhibited retinal ganglion cell apoptosis and optic nerve degeneration, as compared to the sham DDS treated eyes. Immunolocalization revealed drug penetration in the conjunctiva, cornea, iris, and choroid, with residual infliximab in the DDS 3 months after implantation. This reduced-risk biologic DDS improves corneal wound healing and provides retinal neuroprotection, and may be applicable not only to alkali burns but also to other inflammatory surgical procedures such as penetrating keratoplasty and keratoprosthesis implantation.

Design, control, and implementation of LCL-filter-based shunt active power filters

DEFF Research Database (Denmark)

Tang, Yi; Loh, Poh Chiang; Wang, Peng

2011-01-01

This paper concentrates on the design, control and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate harmonic currents produced by nonlinear loads in a three-phase three-wire power system. The use of LCL-filter at the output end of SAPF offer......-loop control system, and active damping implemented with fewer current sensors are all addressed here. An analytical design example is finally presented, being supported with experimental results, to verify its effectiveness and practicality.......This paper concentrates on the design, control and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate harmonic currents produced by nonlinear loads in a three-phase three-wire power system. The use of LCL-filter at the output end of SAPF offers...

Inorganic UV filters

Directory of Open Access Journals (Sweden)

Eloísa Berbel Manaia

2013-06-01

Full Text Available Nowadays, concern over skin cancer has been growing more and more, especially in tropical countries where the incidence of UVA/B radiation is higher. The correct use of sunscreen is the most efficient way to prevent the development of this disease. The ingredients of sunscreen can be organic and/or inorganic sun filters. Inorganic filters present some advantages over organic filters, such as photostability, non-irritability and broad spectrum protection. Nevertheless, inorganic filters have a whitening effect in sunscreen formulations owing to the high refractive index, decreasing their esthetic appeal. Many techniques have been developed to overcome this problem and among them, the use of nanotechnology stands out. The estimated amount of nanomaterial in use must increase from 2000 tons in 2004 to a projected 58000 tons in 2020. In this context, this article aims to analyze critically both the different features of the production of inorganic filters (synthesis routes proposed in recent years and the permeability, the safety and other characteristics of the new generation of inorganic filters.

Particle Kalman Filtering: A Nonlinear Framework for Ensemble Kalman Filters

KAUST Repository

Hoteit, Ibrahim

2010-09-19

Optimal nonlinear filtering consists of sequentially determining the conditional probability distribution functions (pdf) of the system state, given the information of the dynamical and measurement processes and the previous measurements. Once the pdfs are obtained, one can determine different estimates, for instance, the minimum variance estimate, or the maximum a posteriori estimate, of the system state. It can be shown that, many filters, including the Kalman filter (KF) and the particle filter (PF), can be derived based on this sequential Bayesian estimation framework. In this contribution, we present a Gaussian mixture‐based framework, called the particle Kalman filter (PKF), and discuss how the different EnKF methods can be derived as simplified variants of the PKF. We also discuss approaches to reducing the computational burden of the PKF in order to make it suitable for complex geosciences applications. We use the strongly nonlinear Lorenz‐96 model to illustrate the performance of the PKF.

Evidence-Based Evaluation of Inferior Vena Cava Filter Complications Based on Filter Type

Science.gov (United States)

Deso, Steven E.; Idakoji, Ibrahim A.; Kuo, William T.

2016-01-01

Many inferior vena cava (IVC) filter types, along with their specific risks and complications, are not recognized. The purpose of this study was to evaluate the various FDA-approved IVC filter types to determine device-specific risks, as a way to help identify patients who may benefit from ongoing follow-up versus prompt filter retrieval. An evidence-based electronic search (FDA Premarket Notification, MEDLINE, FDA MAUDE) was performed to identify all IVC filter types and device-specific complications from 1980 to 2014. Twenty-three IVC filter types (14 retrievable, 9 permanent) were identified. The devices were categorized as follows: conical (n = 14), conical with umbrella (n = 1), conical with cylindrical element (n = 2), biconical with cylindrical element (n = 2), helical (n = 1), spiral (n = 1), and complex (n = 1). Purely conical filters were associated with the highest reported risks of penetration (90–100%). Filters with cylindrical or umbrella elements were associated with the highest reported risk of IVC thrombosis (30–50%). Conical Bard filters were associated with the highest reported risks of fracture (40%). The various FDA-approved IVC filter types were evaluated for device-specific complications based on best current evidence. This information can be used to guide and optimize clinical management in patients with indwelling IVC filters. PMID:27247477

CLEAR test facility

CERN Multimedia

Ordan, Julien Marius

2017-01-01

A new user facility for accelerator R&D, the CERN Linear Electron Accelerator for Research (CLEAR), started operation in August 2017. CLEAR evolved from the former CLIC Test Facility 3 (CTF3) used by the Compact Linear Collider (CLIC). The new facility is able to host and test a broad range of ideas in the accelerator field.

Higher safety and saving of filter material with multi-way sorption filters

International Nuclear Information System (INIS)

Ohlmeyer, M.; Benzel, M.

1978-01-01

The multi-way filter 'Nuclear Karlsruhe' satisfies the requirements of operational safety, high utilisation of the filter material and low pressure drop. An important factor contributing to increased operational safety is due to the fact that the nearly total utilisation of the filter material eliminates the need for optimisation weighing costs against safety. The reduction in filter material consumption reduces not only the direct procurement costs but also the costs of nuclear plants, is radioactive. This contributes in several respects towards a better protection of the environment. The MWS filter can also be used, and presents the same advantages, in non-nuclear plants. (orig.) [de

Automatic Data Filter Customization Using a Genetic Algorithm

Science.gov (United States)

Mandrake, Lukas

2013-01-01

This work predicts whether a retrieval algorithm will usefully determine CO2 concentration from an input spectrum of GOSAT (Greenhouse Gases Observing Satellite). This was done to eliminate needless runtime on atmospheric soundings that would never yield useful results. A space of 50 dimensions was examined for predictive power on the final CO2 results. Retrieval algorithms are frequently expensive to run, and wasted effort defeats requirements and expends needless resources. This algorithm could be used to help predict and filter unneeded runs in any computationally expensive regime. Traditional methods such as the Fischer discriminant analysis and decision trees can attempt to predict whether a sounding will be properly processed. However, this work sought to detect a subsection of the dimensional space that can be simply filtered out to eliminate unwanted runs. LDAs (linear discriminant analyses) and other systems examine the entire data and judge a "best fit," giving equal weight to complex and problematic regions as well as simple, clear-cut regions. In this implementation, a genetic space of "left" and "right" thresholds outside of which all data are rejected was defined. These left/right pairs are created for each of the 50 input dimensions. A genetic algorithm then runs through countless potential filter settings using a JPL computer cluster, optimizing the tossed-out data s yield (proper vs. improper run removal) and number of points tossed. This solution is robust to an arbitrary decision boundary within the data and avoids the global optimization problem of whole-dataset fitting using LDA or decision trees. It filters out runs that would not have produced useful CO2 values to save needless computation. This would be an algorithmic preprocessing improvement to any computationally expensive system.

Combination of Wiener filtering and singular value decomposition filtering for volume imaging PET

International Nuclear Information System (INIS)

Shao, L.; Lewitt, R.M.; Karp, J.S.

1995-01-01

Although the three-dimensional (3D) multi-slice rebinning (MSRB) algorithm in PET is fast and practical, and provides an accurate reconstruction, the MSRB image, in general, suffers from the noise amplified by its singular value decomposition (SVD) filtering operation in the axial direction. Their aim in this study is to combine the use of the Wiener filter (WF) with the SVD to decrease the noise and improve the image quality. The SVD filtering ''deconvolves'' the spatially variant axial response function while the WF suppresses the noise and reduces the blurring not modeled by the axial SVD filter but included in the system modulation transfer function. Therefore, the synthesis of these two techniques combines the advantages of both filters. The authors applied this approach to the volume imaging HEAD PENN-PET brain scanner with an axial extent of 256 mm. This combined filter was evaluated in terms of spatial resolution, image contrast, and signal-to-noise ratio with several phantoms, such as a cold sphere phantom and 3D brain phantom. Specifically, the authors studied both the SVD filter with an axial Wiener filter and the SVD filter with a 3D Wiener filter, and compared the filtered images to those from the 3D reprojection (3DRP) reconstruction algorithm. Their results indicate that the Wiener filter increases the signal-to-noise ratio and also improves the contrast. For the MSRB images of the 3D brain phantom, after 3D WF, both the Gray/White and Gray/Ventricle ratios were improved from 1.8 to 2.8 and 2.1 to 4.1, respectively. In addition, the image quality with the MSRB algorithm is close to that of the 3DRP algorithm with 3D WF applied to both image reconstructions

Choosing and using astronomical filters

CERN Document Server

Griffiths, Martin

2014-01-01

As a casual read through any of the major amateur astronomical magazines will demonstrate, there are filters available for all aspects of optical astronomy. This book provides a ready resource on the use of the following filters, among others, for observational astronomy or for imaging: Light pollution filters Planetary filters Solar filters Neutral density filters for Moon observation Deep-sky filters, for such objects as galaxies, nebulae and more Deep-sky objects can be imaged in much greater detail than was possible many years ago. Amateur astronomers can take

Robust Ensemble Filtering and Its Relation to Covariance Inflation in the Ensemble Kalman Filter

KAUST Repository

Luo, Xiaodong

2011-12-01

A robust ensemble filtering scheme based on the H∞ filtering theory is proposed. The optimal H∞ filter is derived by minimizing the supremum (or maximum) of a predefined cost function, a criterion different from the minimum variance used in the Kalman filter. By design, the H∞ filter is more robust than the Kalman filter, in the sense that the estimation error in the H∞ filter in general has a finite growth rate with respect to the uncertainties in assimilation, except for a special case that corresponds to the Kalman filter. The original form of the H∞ filter contains global constraints in time, which may be inconvenient for sequential data assimilation problems. Therefore a variant is introduced that solves some time-local constraints instead, and hence it is called the time-local H∞ filter (TLHF). By analogy to the ensemble Kalman filter (EnKF), the concept of ensemble time-local H∞ filter (EnTLHF) is also proposed. The general form of the EnTLHF is outlined, and some of its special cases are discussed. In particular, it is shown that an EnKF with certain covariance inflation is essentially an EnTLHF. In this sense, the EnTLHF provides a general framework for conducting covariance inflation in the EnKF-based methods. Some numerical examples are used to assess the relative robustness of the TLHF–EnTLHF in comparison with the corresponding KF–EnKF method.

Expression of c-Fos and c-Jun in the cornea, lens, and retina after ultraviolet irradiation of the rat eye and effect of topical antisense oligodeoxynucleotides

International Nuclear Information System (INIS)

Gillardon, F.; Zimmermann, M.

1995-01-01

Aims - Immunohistochemical techniques were used to investigate c-Fos and c-Jun proto-oncogene expression in the cornea, lens, and retina after ultraviolet irradiation of the rat eye. Methods -Eyes of anaesthetised rats were exposed to 1.5 J/cm 2 of ultraviolet radiation (280-380 nm). Animals were perfused 1, 6, or 24 hours after irradiation and tissue sections were incubated with specific antiserum to c-Fos and c-Jun, respectively. Non-irradiated contralateral eyes displayed no c-Fos and c-Jun immunoreactivity. One and 6 hours after ultraviolet exposure numerous c-Fos and c-Jun immunopositive nuclei were observed mainly in the epithelial cell layers of the cornea and the lens epithelium. Scattered labelled nuclei were detectable in the retinal ganglion cell layer and the inner nuclear layer. Twenty four hours after irradiation c-Fos and c-Jun protein expression returned to near control levels. Histological signs of ultraviolet damage (for example, chromatin condensation, nuclear fragmentation) were first recognisable in the corneal epithelium 6 hours after irradiation and became more apparent at later times. The rapid and sustained activation of c-Fos and c-Jun expression in the eye after single ultraviolet exposure may represent the molecular mechanism underlying ultraviolet induced photodamage and initiation of cell death. Furthermore, topical application of a c-fos antisense oligode-oxynucleotide to the ultraviolet exposed rat eye inhibited the increase in c-Fos expression in the cornea, suggesting therapeutic activity of antisense drugs in corneal malignant and infectious diseases. (author)

OPTIMIZATION OF ADVANCED FILTER SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

R.A. Newby; G.J. Bruck; M.A. Alvin; T.E. Lippert

1998-04-30

Reliable, maintainable and cost effective hot gas particulate filter technology is critical to the successful commercialization of advanced, coal-fired power generation technologies, such as IGCC and PFBC. In pilot plant testing, the operating reliability of hot gas particulate filters have been periodically compromised by process issues, such as process upsets and difficult ash cake behavior (ash bridging and sintering), and by design issues, such as cantilevered filter elements damaged by ash bridging, or excessively close packing of filtering surfaces resulting in unacceptable pressure drop or filtering surface plugging. This test experience has focused the issues and has helped to define advanced hot gas filter design concepts that offer higher reliability. Westinghouse has identified two advanced ceramic barrier filter concepts that are configured to minimize the possibility of ash bridge formation and to be robust against ash bridges should they occur. The ''inverted candle filter system'' uses arrays of thin-walled, ceramic candle-type filter elements with inside-surface filtering, and contains the filter elements in metal enclosures for complete separation from ash bridges. The ''sheet filter system'' uses ceramic, flat plate filter elements supported from vertical pipe-header arrays that provide geometry that avoids the buildup of ash bridges and allows free fall of the back-pulse released filter cake. The Optimization of Advanced Filter Systems program is being conducted to evaluate these two advanced designs and to ultimately demonstrate one of the concepts in pilot scale. In the Base Contract program, the subject of this report, Westinghouse has developed conceptual designs of the two advanced ceramic barrier filter systems to assess their performance, availability and cost potential, and to identify technical issues that may hinder the commercialization of the technologies. A plan for the Option I, bench

Generalised Filtering

Directory of Open Access Journals (Sweden)

Karl Friston

2010-01-01

Full Text Available We describe a Bayesian filtering scheme for nonlinear state-space models in continuous time. This scheme is called Generalised Filtering and furnishes posterior (conditional densities on hidden states and unknown parameters generating observed data. Crucially, the scheme operates online, assimilating data to optimize the conditional density on time-varying states and time-invariant parameters. In contrast to Kalman and Particle smoothing, Generalised Filtering does not require a backwards pass. In contrast to variational schemes, it does not assume conditional independence between the states and parameters. Generalised Filtering optimises the conditional density with respect to a free-energy bound on the model's log-evidence. This optimisation uses the generalised motion of hidden states and parameters, under the prior assumption that the motion of the parameters is small. We describe the scheme, present comparative evaluations with a fixed-form variational version, and conclude with an illustrative application to a nonlinear state-space model of brain imaging time-series.

Sub-micron filter

Science.gov (United States)

Tepper, Frederick [Sanford, FL; Kaledin, Leonid [Port Orange, FL

2009-10-13

Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2/g have been found to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of microbes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolecules such as proteins may be separated from each other based on their electronegative charges.

Retrievable Inferior vena cava filters in pregnancy: Risk versus benefit?

Science.gov (United States)

Crosby, David A; Ryan, Kevin; McEniff, Niall; Dicker, Patrick; Regan, Carmen; Lynch, Caoimhe; Byrne, Bridgette

2018-03-01

shows that the filter appears to protect against PE in pregnancy but the numbers are small. Complications such as filter thrombosis and IVC penetration appear to be higher in pregnancy but this difference is not statistically significant. It is not possible to retrieve the device in one out of every four pregnant women. This has implications in terms of long term risk of lower limb thrombosis and post thrombotic syndrome. The decision to use an IVC filter in pregnancy needs careful consideration by a multidisciplinary team. The benefit and risk assessment should be individualised and clearly outlined to the patient. Copyright © 2017 Elsevier B.V. All rights reserved.

Recirculating electric air filter

Science.gov (United States)

Bergman, W.

1985-01-09

An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Kaon Filtering For CLAS Data

International Nuclear Information System (INIS)

McNabb, J.

2001-01-01

The analysis of data from CLAS is a multi-step process. After the detectors for a given running period have been calibrated, the data is processed in the so called pass-1 cooking. During the pass-1 cooking each event is reconstructed by the program a1c which finds particle tracks and computes momenta from the raw data. The results are then passed on to several data monitoring and filtering utilities. In CLAS software, a filter is a parameterless function which returns an integer indicating whether an event should be kept by that filter or not. There is a main filter program called g1-filter which controls several specific filters and outputs several files, one for each filter. These files may then be analyzed separately, allowing individuals interested in one reaction channel to work from smaller files than using the whole data set would require. There are several constraints on what the filter functions should do. Obviously, the filtered files should be as small as possible, however the filter should also not reject any events that might be used in the later analysis for which the filter was intended

From Microwave Filter to Digital Filter and Back Again

DEFF Research Database (Denmark)

Dalby, Arne Brejning

1989-01-01

A new very simple state variable flow graph representation for interdigital transmission line bandpass filters is presented, which has led to two important results: 1) A new type of digital filter with properties, that surpass the properties of most other (all pole) digital filtertypes. 2) The st...

Functional imaging in bulk tissue specimens using optical emission tomography: fluorescence preservation during optical clearing

International Nuclear Information System (INIS)

Sakhalkar, H S; Dewhirst, M; Oliver, T; Cao, Y; Oldham, M

2007-01-01

Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate or BABB

Functional imaging in bulk tissue specimens using optical emission tomography: fluorescence preservation during optical clearing

Energy Technology Data Exchange (ETDEWEB)

Sakhalkar, H S [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Dewhirst, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oliver, T [Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 (United States); Cao, Y [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oldham, M [Department of Radiation Oncology Physics, and Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 (United States)

2007-04-21

Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate

Filter apparatus

International Nuclear Information System (INIS)

Butterworth, D.J.

1980-01-01

This invention relates to liquid filters, precoated by replaceable powders, which are used in the production of ultra pure water required for steam generation of electricity. The filter elements are capable of being installed and removed by remote control so that they can be used in nuclear power reactors. (UK)

Filtering and prediction

CERN Document Server

Fristedt, B; Krylov, N

2007-01-01

Filtering and prediction is about observing moving objects when the observations are corrupted by random errors. The main focus is then on filtering out the errors and extracting from the observations the most precise information about the object, which itself may or may not be moving in a somewhat random fashion. Next comes the prediction step where, using information about the past behavior of the object, one tries to predict its future path. The first three chapters of the book deal with discrete probability spaces, random variables, conditioning, Markov chains, and filtering of discrete Markov chains. The next three chapters deal with the more sophisticated notions of conditioning in nondiscrete situations, filtering of continuous-space Markov chains, and of Wiener process. Filtering and prediction of stationary sequences is discussed in the last two chapters. The authors believe that they have succeeded in presenting necessary ideas in an elementary manner without sacrificing the rigor too much. Such rig...

The intractable cigarette 'filter problem'.

Science.gov (United States)

Harris, Bradford

2011-05-01

When lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the industry identified as the 'filter problem'. These extensive filter research and development efforts suggest a phase of genuine optimism among cigarette designers that cigarette filters could be engineered to mitigate the health hazards of smoking. This paper explores the early history of cigarette filter research and development in order to elucidate why and when seemingly sincere filter engineering efforts devolved into manipulations in cigarette design to sustain cigarette marketing and mitigate consumers' concerns about the health consequences of smoking. Relevant word and phrase searches were conducted in the Legacy Tobacco Documents Library online database, Google Patents, and media and medical databases including ProQuest, JSTOR, Medline and PubMed. 13 tobacco industry documents were identified that track prominent developments involved in what the industry referred to as the 'filter problem'. These reveal a period of intense focus on the 'filter problem' that persisted from the mid-1950s to the mid-1960s, featuring collaborations between cigarette producers and large American chemical and textile companies to develop effective filters. In addition, the documents reveal how cigarette filter researchers' growing scientific knowledge of smoke chemistry led to increasing recognition that filters were unlikely to offer significant health protection. One of the primary concerns of cigarette producers was to design cigarette filters that could be economically incorporated into the massive scale of cigarette production. The synthetic plastic cellulose acetate

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

Energy Technology Data Exchange (ETDEWEB)

Kontson, Kimberly, E-mail: Kimberly.Kontson@fda.hhs.gov; Jennings, Robert J. [Department of Bioengineering, University of Maryland, College Park, Maryland 20742 and Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States)

2015-09-15

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

International Nuclear Information System (INIS)

Kontson, Kimberly; Jennings, Robert J.

2015-01-01

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity

77 FR 37803 - Customer Clearing Documentation, Timing of Acceptance for Clearing, and Clearing Member Risk...

Science.gov (United States)

2012-06-25

..., 202-418-6703, [email protected] , Division of Clearing and Risk, and Camden Nunery, Economist, 202-418-5723, Office of the Chief Economist, Commodity Futures Trading Commission, Three Lafayette Centre, 1155...

Concentric Split Flow Filter

Science.gov (United States)

Stapleton, Thomas J. (Inventor)

2015-01-01

A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

Irradiation of the rabbit cornea with UVB rays stimulates the expression of nitric oxide synthases-generated nitric oxide and the formation of cytotoxic nitrogen-related oxidants

Czech Academy of Sciences Publication Activity Database

Čejková, Jitka; Ardan, Taras; Andonova, Janetta; Zídek, Zdeněk

2005-01-01

Roč. 20, - (2005), s. 467-473 ISSN 0213-3911 R&D Projects: GA ČR GA304/03/0419 Institutional research plan: CEZ:AV0Z5008914 Keywords : UVB rays * Reactive nitrogen species * Cornea Subject RIV: FF - HEENT, Dentistry Impact factor: 2.023, year: 2005

Rotationally invariant correlation filtering

International Nuclear Information System (INIS)

Schils, G.F.; Sweeney, D.W.

1985-01-01

A method is presented for analyzing and designing optical correlation filters that have tailored rotational invariance properties. The concept of a correlation of an image with a rotation of itself is introduced. A unified theory of rotation-invariant filtering is then formulated. The unified approach describes matched filters (with no rotation invariance) and circular-harmonic filters (with full rotation invariance) as special cases. The continuum of intermediate cases is described in terms of a cyclic convolution operation over angle. The angular filtering approach allows an exact choice for the continuous trade-off between loss of the correlation energy (or specificity regarding the image) and the amount of rotational invariance desired

Tear dysfunction and the cornea: LXVIII Edward Jackson Memorial Lecture.

Science.gov (United States)

Pflugfelder, Stephen C

2011-12-01

To describe the cause and consequence of tear dysfunction-related corneal disease. Perspective on effects of tear dysfunction on the cornea. Evidence is presented on the effects of tear dysfunction on corneal morphology, function, and health, as well as efficacy of therapies for tear dysfunction-related corneal disease. Tear dysfunction is a prevalent eye disease and the most frequent cause for superficial corneal epithelial disease that results in corneal barrier disruption, an irregular optical surface, light scattering, optical aberrations, and exposure and sensitization of pain-sensing nerve endings (nociceptors). Tear dysfunction-related corneal disease causes irritation and visual symptoms such as photophobia and blurred and fluctuating vision that may decrease quality of life. Dysfunction of 1 or more components of the lacrimal functional unit results in changes in tear composition, including elevated osmolarity and increased concentrations of matrix metalloproteinases, inflammatory cytokines, and chemokines. These tear compositional changes promote disruption of tight junctions, alter differentiation, and accelerate death of corneal epithelial cells. Corneal epithelial disease resulting from tear dysfunction causes eye irritation and decreases visual function. Clinical and basic research has improved understanding of the pathogenesis of tear dysfunction-related corneal epithelial disease, as well as treatment outcomes. Copyright © 2011 Elsevier Inc. All rights reserved.

Clearing and vegetation management issues

International Nuclear Information System (INIS)

Anon.

1994-01-01

Clearing and continued management of incompatible plant species is critical to maintaining safe and reliable transmission and distribution lines at British Columbia Hydro. As part of a general review of policies regarding rights-of-way, the clearing of BC Hydro rights-of-way was studied by a task team in order to formulate a set of recommended policies and procedures to guide employees in all rights-of-way decisions, and to provide clear direction for resolution of all rights-of-way issues in a cost-effective manner. Issues reviewed were: clearing standards and line security standardization for transmission circuits; clearing rights for removal of trees or management of vegetation beyond the statutory right-of-way; clearing and vegetation management procedures; tree replacement; arboricultural techniques; periodic reviewing of clearing practices; compensation for tree removal; herbicide use; and heritage and wildlife trees. Justification for the recommendation is provided along with alternate options and costs of compliance

Monolithic Integrated Ceramic Waveguide Filters

OpenAIRE

Hunter, IC; Sandhu, MY

2014-01-01

Design techniques for a new class of integrated monolithic high permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled TEM filters with the same unloaded Q-Factor. Designs for both chebyshev and asymmetric generalized chebyshev filter are presented, with experimental results for an 1800 MHz chebyshev filter showing excellent agreement with theory.

Shifted-modified Chebyshev filters

OpenAIRE

ŞENGÜL, Metin

2013-01-01

This paper introduces a new type of filter approximation method that utilizes shifted-modified Chebyshev filters. Construction of the new filters involves the use of shifted-modified Chebyshev polynomials that are formed using the roots of conventional Chebyshev polynomials. The study also includes 2 tables containing the shifted-modified Chebyshev polynomials and the normalized element values for the low-pass prototype filters up to degree 6. The transducer power gain, group dela...

Examination of cryogenic filters for multistage RF filtering in ultralow temperature experiments

Science.gov (United States)

Zavyalov, V. V.; Chernyaev, S. A.; Shein, K. V.; Shukaleva, A. G.; Arutyunov, K. Yu

2018-03-01

Cryo-filters are essential while studying electronic properties of nanoscale structures at very low temperatures. In this report we present the simple measuring methodology and experimental impedance characteristics of customized lumped filters cooled down to 4.2K in the 10 Hz-500 MHz frequency range. In particular, we tested the home-made permalloy-core RL filters, the MurataTMChip Ferrite Bead filter, and the ToshibaTMAmobeadsTMcores. We use the high-frequency generalization of four-terminal sensing method to account for the wiring retardation effects, which are important when working with ultralow temperature systems.

Flexible time-varying filter banks

Science.gov (United States)

Tuncer, Temel E.; Nguyen, Truong Q.

1993-09-01

Linear phase maximally flat FIR Butterworth filter approximations are discussed and a new filter design method is introduced. This variable cutoff filter design method uses the cosine modulated versions of a prototype filter. The design procedure is simple and different variants of this procedure can be used to obtain close to optimum linear phase filters. Using this method, flexible time-varying filter banks with good reconstruction error are introduced. These types of oversampled filter banks have small magnitude error which can be easily controlled by the appropriate choice of modulation frequency. This error can be further decreased by magnitude equalization without increasing the computational complexity considerably. Two dimensional design examples are also given.

Design and implementation of predictive filtering system for current reference generation of active power filter

Energy Technology Data Exchange (ETDEWEB)

Kilic, Tomislav; Milun, Stanko; Petrovic, Goran [FESB University of Split, Faculty of Electrical Engineering, Machine Engineering and Naval Architecture, R. Boskovica bb, 21000, Split (Croatia)

2007-02-15

The shunt active power filters are used to attenuate the harmonic currents in power systems by injecting equal but opposite compensating currents. Successful control of the active filters requires an accurate current reference. In this paper the current reference determination based on predictive filtering structure is presented. Current reference was obtained by taking the difference of load current and its fundamental harmonic. For fundamental harmonic determination with no time delay a combination of digital predictive filter and low pass filter is used. The proposed method was implemented on a laboratory prototype of a three-phase active power filter. The algorithm for current reference determination was adapted and implemented on DSP controller. Simulation and experimental results show that the active power filter with implemented predictive filtering structure gives satisfactory performance in power system harmonic attenuation. (author)

Blurred image restoration using knife-edge function and optimal window Wiener filtering

Science.gov (United States)

Zhou, Shudao; Yan, Wei

2018-01-01

Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects. PMID:29377950

ESTUDO HISTOPATÓLOGICO NAS CÓRNEAS DOS CÃES TRATADOS COM 2-1 FOSFATO DISSÓDICO DE BETAMETASONA E FOSFATO DISSÓDICO/ACETATO DE DEXAMETASONA, QUE RECEBERAM TRASPLANTES COM CÓRNEAS DE SUÍNOS HISTOPHATOLOGICAL STUDY IN CORNEAS OF DOGS, TREATED WITH 2-1 DISSODIC FOSPHATE OF BETAMETHASONE AND DISSODIC FOSPHATED/ACETATE OF DEXAMETHASONE, THAT HAD RECEIVED IMPLANTATION OF SWINE CORNEAS

Directory of Open Access Journals (Sweden)

Luiz Antônio Franco da Silva

2007-09-01

Full Text Available

Foram utilizados 10 cães, sem raça definida, com peso médio de 10kg, examinados e considerados sadios. Cada cão, a seu tempo, teve implantada no olho esquerdo córnea de suíno, conservada em câmara úmida pelo período máximo de seis horas. Cada animal antes da cirurgia recebeu 4 mg de fosfato dissódico/acetato de dexametasona, por via intramuscular, e uma gota de fosfato dissódico de betametasona/sulfato de gentamicina colírio. Conservou-se a medicação ocular 4 vezes/dia e a intramuscular semanalmente, até o sacrifício do cão. Cada qual foi sacrificado por processo indolor (thiopental sódico + cloreto de succinilcolina e teve o olho que recebeu implante com córnea de suíno enucleado. Foi injetado formol 10% na câmara do vítreo e a córnea foi removida com aba escleral, tratada e corada com hematoxilina-eosina. Foram analisadas as seguintes áreas: enxerto, áreas adjacentes receptoras e observadas as várias alterações.

PALAVRAS-CHAVE: Histopatologia; corticosteróides; xenotransplantes; córnea; canino; suíno.

Ten dogs, with no definitive breed, average weight of 10 kg, were in this research. After being examined and considered healthy they received numbers, from 11 to 20 in their collars. Each dog received implantation, in the left eye, of swine cornea, obtained at Casa de Banha Caçula, a slaughterhouse, and maintained in wet chamber for six hours at most. Before surgery, each animal received 4 mg of dissodic phosphate/acetate dexamethasone IM and, once a week one drop of dissodic phosphate betamethasone and gentamicin sulphate, four times a day, until the 28th day. when the animals were sacrificed through painless process (Thiopental sodic

Design and control of LCL-filter with active damping for Active Power Filter

DEFF Research Database (Denmark)

Zeng, Guohong; Rasmussen, Tonny Wederberg; Ma, L

2010-01-01

of LCL-filter for APF is introduced, which is aimed for simplified the implementation. To suppress the resonance that may be excited in the system, which brings in stability problems, an active damping control strategy using the current feed-back of the filter capacitor is adopted. By selecting two equal......In the application of shunt Active Power Filter (APF) to compensate nonlinear load's harmonic, reactive and negative sequence current, it is more effective to use a LCL-filter than an L-filter as an interface between the Voltage Source Converter (VSC) and grid. In this paper, a designing procedure...... or similar inductances, the filter designing become more simple and effective, meanwhile the capacitance requirement is minimized. A pole-zero automatic cancellation phenomenon is discussed in this paper, which can be applied to simplify the current regulator designing. The tuning method is presented, based...

Digital Filters for Low Frequency Equalization

DEFF Research Database (Denmark)

Tyril, Marni; Abildgaard, J.; Rubak, Per

2001-01-01

Digital filters with high resolution in the low-frequency range are studied. Specifically, for a given computational power, traditional IIR filters are compared with warped FIR filters, warped IIR filters, and modified warped FIR filters termed warped individual z FIR filters (WizFIR). The results...

Vectorization of linear discrete filtering algorithms

Science.gov (United States)

Schiess, J. R.

1977-01-01

Linear filters, including the conventional Kalman filter and versions of square root filters devised by Potter and Carlson, are studied for potential application on streaming computers. The square root filters are known to maintain a positive definite covariance matrix in cases in which the Kalman filter diverges due to ill-conditioning of the matrix. Vectorization of the filters is discussed, and comparisons are made of the number of operations and storage locations required by each filter. The Carlson filter is shown to be the most efficient of the filters on the Control Data STAR-100 computer.

Filtered-X Affine Projection Algorithms for Active Noise Control Using Volterra Filters

Directory of Open Access Journals (Sweden)

Sicuranza Giovanni L

2004-01-01

Full Text Available We consider the use of adaptive Volterra filters, implemented in the form of multichannel filter banks, as nonlinear active noise controllers. In particular, we discuss the derivation of filtered-X affine projection algorithms for homogeneous quadratic filters. According to the multichannel approach, it is then easy to pass from these algorithms to those of a generic Volterra filter. It is shown in the paper that the AP technique offers better convergence and tracking capabilities than the classical LMS and NLMS algorithms usually applied in nonlinear active noise controllers, with a limited complexity increase. This paper extends in two ways the content of a previous contribution published in Proc. IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03, Grado, Italy, June 2003. First of all, a general adaptation algorithm valid for any order of affine projections is presented. Secondly, a more complete set of experiments is reported. In particular, the effects of using multichannel filter banks with a reduced number of channels are investigated and relevant results are shown.

Long-term field-scale experiment on using lime filters in an agricultural catchment.

Science.gov (United States)

Kirkkala, Teija; Ventelä, Anne-Mari; Tarvainen, Marjo

2012-01-01

The River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site lime-sand filters (F1, F2, and F3), established within or on the edge of the buffer zones. The filters contain burnt lime (CaO) or spent lime [CaO, Ca(OH), and CaCO]. Easily soluble lime results in a high pH level (>11) and leads to an efficient precipitation of soluble phosphorus (P) from the runoff. Water samples were taken from the inflow and outflow of each site in different hydrological situations. The length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 significantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. The proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt lime and the other spent lime. Both filter parts removed PTOT and SS efficiently from the water; the burnt-lime part also removed DRP. The mixed-lime part removed DRP for a year, but then the efficiency decreased. The effect of filters on nitrogen compounds varied. We conclude that sand filters incorporating lime can be used together with buffer zones to reduce both P and SS load to watercourses. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Device for filtering gaseous media

International Nuclear Information System (INIS)

Benzel, M.

1978-01-01

The air filter system for gaseous radioactive substances consists of a vertical chamber with filter material (charcoal, e.g. impregnated). On one side of the chamber there is an inlet compartment and an outlet compartment. On the other side a guiding compartment turns the gas flow coming from the natural-air side through the lower part of filter chamber to the upper part of the filter. The gas flow leaves the upper part through the outlet conpartment as cleaned-air flow. The filter material may be filled into the chamber from above and drawn off below. For better utilization of the filter material the filter chamber is separated by means of a wall between the inlet and outlet compartment. This partition wall consist of two sheets arranged one above the other provided with slots which may be superposed in alignment. In this case filter material is tickling from the upper part of the chamber into the lower part avoiding to form a crater in the filter bed. (DG) [de

DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.

Science.gov (United States)

The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...

Hydrodynamics of microbial filter feeding.

Science.gov (United States)

Nielsen, Lasse Tor; Asadzadeh, Seyed Saeed; Dölger, Julia; Walther, Jens H; Kiørboe, Thomas; Andersen, Anders

2017-08-29

Microbial filter feeders are an important group of grazers, significant to the microbial loop, aquatic food webs, and biogeochemical cycling. Our understanding of microbial filter feeding is poor, and, importantly, it is unknown what force microbial filter feeders must generate to process adequate amounts of water. Also, the trade-off in the filter spacing remains unexplored, despite its simple formulation: A filter too coarse will allow suitably sized prey to pass unintercepted, whereas a filter too fine will cause strong flow resistance. We quantify the feeding flow of the filter-feeding choanoflagellate Diaphanoeca grandis using particle tracking, and demonstrate that the current understanding of microbial filter feeding is inconsistent with computational fluid dynamics (CFD) and analytical estimates. Both approaches underestimate observed filtration rates by more than an order of magnitude; the beating flagellum is simply unable to draw enough water through the fine filter. We find similar discrepancies for other choanoflagellate species, highlighting an apparent paradox. Our observations motivate us to suggest a radically different filtration mechanism that requires a flagellar vane (sheet), something notoriously difficult to visualize but sporadically observed in the related choanocytes (sponges). A CFD model with a flagellar vane correctly predicts the filtration rate of D. grandis , and using a simple model we can account for the filtration rates of other microbial filter feeders. We finally predict how optimum filter mesh size increases with cell size in microbial filter feeders, a prediction that accords very well with observations. We expect our results to be of significance for small-scale biophysics and trait-based ecological modeling.

Effects of ERV Filter Degradation on Indoor CO2 Levels of a Classroom

Directory of Open Access Journals (Sweden)

Jae-Sol Choi

2018-04-01

Full Text Available Energy recovery ventilators (ERVs are widely used to reduce energy losses caused by ventilation and improve indoor air quality for recently-constructed buildings. It is important for spaces with high occupancy density and longer residence times, such as classrooms. In classrooms, the ERV size is typically estimated by the target number of students in the design phase, but the design air volume flow rates (m3/h of the ERV can decrease over time owing to filter degradation such as increased dust loading. In this study, field tests are conducted in a classroom to investigate filter degradation through a visual inspection and by measuring the air volume flow rates at the diffusers connected to the ERV. In addition, variations in carbon dioxide (CO2 concentrations are also measured to verify the effects of filter degradation on the indoor CO2 levels over the entire test period, which includes filter replacement, as well. As the tests are conducted during classes, several adjusting methodologies are proposed to match the different test conditions. The results show that the total air volume flow rate of the ERV increases after the filter replacement (546 to 766 m3/h, but it again decreases as time elapses (659 m3/h. Accordingly, the indoor CO2 concentration decreases after the filter replacement by more than 300 ppm (1404 to 1085 ppm, clearly showing the effect of filter degradation. However, this CO2 concentration remains similar for four months after the replacement, and the total air volume rate decreases again. An interpretation is made using computational fluid dynamics analysis that the measured CO2 concentrations are affected by airflow patterns. The airflow in the cooling system may dilute CO2 concentrations at the measuring location. Thus, periodic filter replacement and management are important to ensure the desired ERV air volume rates and consequently the desired indoor CO2 concentrations.

Nd:YAG (2 omega) pumped dye laser using self-filtering unstable resonator

CERN Document Server

Rahimian, K; Hariri, H

2002-01-01

A self-filtering unstable resonator with a magnification of M=-3 in a Nd:YAG (2 omega) dye laser has been studied. The dye solution is Rhodamine 6 G in alcohol with the concentration of 5*10 sub - 3 Mol/lit. The spatial intensity distribution of the resonator has been compared has been compared with that of a plane-parallel resonator of equal length. The output energy in both configurations are comparable (20 mu J ,and 26 mu J ,respectively). A significant difference between these two resonators is the laser beam divergence, where beam divergences of 0.77 mrad for the self-filtering unstable resonator and 1.6 mrad for the plane-parallel resonator have been measured. The brightness corresponding to these two resonators are 1.5* 10 sub 1 1 and 2.2* 10 sub 1 0W.cm sub - 2.Sr sub - 1, and the pulse widths are 7 and 17 ns, respectively. These figures show clearly that laser resonator based on the self-filtering unstable resonator design an increase the laser brightness a factor of 10, with a beam divergence of a f...

Ceramic fiber reinforced filter

Science.gov (United States)

Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

1991-01-01

A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

Multiple Bloch surface waves in visible region of light at the interfaces between rugate filter/rugate filter and rugate filter/dielectric slab/rugate filter

Science.gov (United States)

Ullah Manzoor, Habib; Manzoor, Tareq; Hussain, Masroor; Manzoor, Sanaullah; Nazar, Kashif

2018-04-01

Surface electromagnetic waves are the solution of Maxwell’s frequency domain equations at the interface of two dissimilar materials. In this article, two canonical boundary-value problems have been formulated to analyze the multiplicity of electromagnetic surface waves at the interface between two dissimilar materials in the visible region of light. In the first problem, the interface between two semi-infinite rugate filters having symmetric refractive index profiles is considered and in the second problem, to enhance the multiplicity of surface electromagnetic waves, a homogeneous dielectric slab of 400 nm is included between two semi-infinite symmetric rugate filters. Numerical results show that multiple Bloch surface waves of different phase speeds, different polarization states, different degrees of localization and different field profiles are propagated at the interface between two semi-infinite rugate filters. Having two interfaces when a homogeneous dielectric layer is placed between two semi-infinite rugate filters has increased the multiplicity of electromagnetic surface waves.

Guided filtering for solar image/video processing

Directory of Open Access Journals (Sweden)

Long Xu

2017-06-01

Full Text Available A new image enhancement algorithm employing guided filtering is proposed in this work for enhancement of solar images and videos, so that users can easily figure out important fine structures imbedded in the recorded images/movies for solar observation. The proposed algorithm can efficiently remove image noises, including Gaussian and impulse noises. Meanwhile, it can further highlight fibrous structures on/beyond the solar disk. These fibrous structures can clearly demonstrate the progress of solar flare, prominence coronal mass emission, magnetic field, and so on. The experimental results prove that the proposed algorithm gives significant enhancement of visual quality of solar images beyond original input and several classical image enhancement algorithms, thus facilitating easier determination of interesting solar burst activities from recorded images/movies.

Isolation and characterization of soluble sulfated polysaccharide from the red seaweed Glucaric cornea

International Nuclear Information System (INIS)

Melo, Marcia R.S.; Freitas, Ana L.P.; Feitosa, Judith P.A.; Paula, Regina C.M. de

2001-01-01

The composition, structure and rheological properties of soluble sulphated polysaccharide Glucaric cornea from Brazilian red seaweeds were investigated. The main components of polysaccharide were 3,6-anhydrogalactose (24.7%) and galactose (64.6%). In addition, minor components as 6-O-methyl-galactose (8.5%), glucose (1.5%), xylose (0.7%) and sulfated groups (4.8%) were detected. Comparison between sulphates content determined by Ft-IR spectroscopy and micro elemental analysis was made. Data from 13 C NMR and FT-IR provided evidence of sulphation in C-4 and C-6 of galactose. No gelation with 1.5, 2.0 and 3.0 % (w/v) aqueous solution was observed, even cooled up to 4 deg C. GPC indicated two majors polysaccharide fractions of M pk 7.4 x 10 4 and 1.8 x 10 4 g/mol and a minor fraction of M pk 2.1 x 10 6 g/mol. (author)

Active RC filter based implementation analysis part of two channel hybrid filter bank

Directory of Open Access Journals (Sweden)

Stojanović Vidosav

2014-01-01

Full Text Available In the present paper, a new design method for continuous-time powersymmetric active RC filters for Hybrid Filter Bank (HFB is proposed. Some theoretical properties of continious-time power-symmetric filters bank in a more general perspective are studied. This includes the derivation of a new general analytical form, and a study of poles and zeros locations in s-plane. In the proposed design method the analytic solution of filter coefficients is solved in sdomain using only one nonlinear equation Finally, the proposed approximation is compared to standard approximations. It was shown that attenuation and group delay characteristic of the proposed filter lie between Butterworth and elliptic characteristics. [Projekat Ministarstva nauke Republike Srbije, br. 32009TR

Development of an optimal filter substrate for the identification of small microplastic particles in food by micro-Raman spectroscopy.

Science.gov (United States)

Oßmann, Barbara E; Sarau, George; Schmitt, Sebastian W; Holtmannspötter, Heinrich; Christiansen, Silke H; Dicke, Wilhelm

2017-06-01

When analysing microplastics in food, due to toxicological reasons it is important to achieve clear identification of particles down to a size of at least 1 μm. One reliable, optical analytical technique allowing this is micro-Raman spectroscopy. After isolation of particles via filtration, analysis is typically performed directly on the filter surface. In order to obtain high qualitative Raman spectra, the material of the membrane filters should not show any interference in terms of background and Raman signals during spectrum acquisition. To facilitate the usage of automatic particle detection, membrane filters should also show specific optical properties. In this work, beside eight different, commercially available membrane filters, three newly designed metal-coated polycarbonate membrane filters were tested to fulfil these requirements. We found that aluminium-coated polycarbonate membrane filters had ideal characteristics as a substrate for micro-Raman spectroscopy. Its spectrum shows no or minimal interference with particle spectra, depending on the laser wavelength. Furthermore, automatic particle detection can be applied when analysing the filter surface under dark-field illumination. With this new membrane filter, analytics free of interference of microplastics down to a size of 1 μm becomes possible. Thus, an important size class of these contaminants can now be visualized and spectrally identified. Graphical abstract A newly developed aluminium coated polycarbonate membrane filter enables automatic particle detection and generation of high qualitative Raman spectra allowing identification of small microplastics.

Analog filters in nanometer CMOS

CERN Document Server

Uhrmann, Heimo; Zimmermann, Horst

2014-01-01

Starting from the basics of analog filters and the poor transistor characteristics in nanometer CMOS 10 high-performance analog filters developed by the authors in 120 nm and 65 nm CMOS are described extensively. Among them are gm-C filters, current-mode filters, and active filters for system-on-chip realization for Bluetooth, WCDMA, UWB, DVB-H, and LTE applications. For the active filters several operational amplifier designs are described. The book, furthermore, contains a review of the newest state of research on low-voltage low-power analog filters. To cover the topic of the book comprehensively, linearization issues and measurement methods for the characterization of advanced analog filters are introduced in addition. Numerous elaborate illustrations promote an easy comprehension. This book will be of value to engineers and researchers in industry as well as scientists and Ph.D students at universities. The book is also recommendable to graduate students specializing on nanoelectronics, microelectronics ...

Toward the Development of a Coupled COAMPS-ROMS Ensemble Kalman Filter and Adjoint with a focus on the Indian Ocean and the Intraseasonal Oscillation

Science.gov (United States)

2015-09-30

1 Approved for public release; distribution is unlimited. Toward the Development of a Coupled COAMPS-ROMS Ensemble Kalman Filter and Adjoint...system at NCAR. (2) Compare the performance of the Ensemble Kalman Filter (EnKF) using the Data Assimilation Research Testbed (DART) and 4...undercurrent is clearly visible. Figure 2 shows the horizontal temperature structure and circulation at a depth of 50 m within the surface mixed layer

Optimizing the reconstruction filter in cone-beam CT to improve periodontal ligament space visualization: An in vitro study

International Nuclear Information System (INIS)

Houno, Yuuki; Kodera, Yoshie; Hishikawa, Toshimitsu; Naitoh, Munetaka; Mitani, Akio; Noguchi, Toshihide; Ariji, Eiichiro; Gotoh, Kenichi

2017-01-01

Evaluation of alveolar bone is important in the diagnosis of dental diseases. The periodontal ligament space is difficult to clearly depict in cone-beam computed tomography images because the reconstruction filter conditions during image processing cause image blurring, resulting in decreased spatial resolution. We examined different reconstruction filters to assess their ability to improve spatial resolution and allow for a clearer visualization of the periodontal ligament space. Cone-beam computed tomography projections of 2 skull phantoms were reconstructed using 6 reconstruction conditions and then compared using the Thurstone paired comparison method. Physical evaluations, including the modulation transfer function and the Wiener spectrum, as well as an assessment of space visibility, were undertaken using experimental phantoms. Image reconstruction using a modified Shepp-Logan filter resulted in better sensory, physical, and quantitative evaluations. The reconstruction conditions substantially improved the spatial resolution and visualization of the periodontal ligament space. The difference in sensitivity was obtained by altering the reconstruction filter. Modifying the characteristics of a reconstruction filter can generate significant improvement in assessments of the periodontal ligament space. A high-frequency enhancement filter improves the visualization of thin structures and will be useful when accurate assessment of the periodontal ligament space is necessary

Optimizing the reconstruction filter in cone-beam CT to improve periodontal ligament space visualization: An in vitro study

Energy Technology Data Exchange (ETDEWEB)

Houno, Yuuki; Kodera, Yoshie [Graduate School of Medicine, Nagoya University, Nagoya (Japan); Hishikawa, Toshimitsu; Naitoh, Munetaka; Mitani, Akio; Noguchi, Toshihide; Ariji, Eiichiro [Aichi Gakuin University, Nisshin (Japan); Gotoh, Kenichi [Div. of Radiology, Dental Hospital, Aichi Gakuin University, Nisshin (Japan)

2017-09-15

Evaluation of alveolar bone is important in the diagnosis of dental diseases. The periodontal ligament space is difficult to clearly depict in cone-beam computed tomography images because the reconstruction filter conditions during image processing cause image blurring, resulting in decreased spatial resolution. We examined different reconstruction filters to assess their ability to improve spatial resolution and allow for a clearer visualization of the periodontal ligament space. Cone-beam computed tomography projections of 2 skull phantoms were reconstructed using 6 reconstruction conditions and then compared using the Thurstone paired comparison method. Physical evaluations, including the modulation transfer function and the Wiener spectrum, as well as an assessment of space visibility, were undertaken using experimental phantoms. Image reconstruction using a modified Shepp-Logan filter resulted in better sensory, physical, and quantitative evaluations. The reconstruction conditions substantially improved the spatial resolution and visualization of the periodontal ligament space. The difference in sensitivity was obtained by altering the reconstruction filter. Modifying the characteristics of a reconstruction filter can generate significant improvement in assessments of the periodontal ligament space. A high-frequency enhancement filter improves the visualization of thin structures and will be useful when accurate assessment of the periodontal ligament space is necessary.

Ventilation filters as sources of air pollution – Processes occurring on surfaces of used filters

DEFF Research Database (Denmark)

Bekö, Gabriel; Halás, Oto; Clausen, Geo

2004-01-01

Ozone concentrations were monitored upstream and downstream of used filter samples following 24hours of ventilation with ozone- filtered air. The ozone concentration in the air upstream of the filters was maintained at ~75 ppb while the concentration downstream of the filters was initially betwee...

Spatial filtering with photonic crystals

Energy Technology Data Exchange (ETDEWEB)

Maigyte, Lina [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Staliunas, Kestutis [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, Barcelona 08010 (Spain)

2015-03-15

Photonic crystals are well known for their celebrated photonic band-gaps—the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic crystals can be utilized for frequency filtering. In analogy to the chromatic band-gaps and the frequency filtering, the angular band-gaps and the angular (spatial) filtering are also possible in photonic crystals. In this article, we review the recent advances of the spatial filtering using the photonic crystals in different propagation regimes and for different geometries. We review the most evident configuration of filtering in Bragg regime (with the back-reflection—i.e., in the configuration with band-gaps) as well as in Laue regime (with forward deflection—i.e., in the configuration without band-gaps). We explore the spatial filtering in crystals with different symmetries, including axisymmetric crystals; we discuss the role of chirping, i.e., the dependence of the longitudinal period along the structure. We also review the experimental techniques to fabricate the photonic crystals and numerical techniques to explore the spatial filtering. Finally, we discuss several implementations of such filters for intracavity spatial filtering.

Design and Analysis of Robust Active Damping for LCL Filters using Digital Notch Filters

DEFF Research Database (Denmark)

Yao, Wenli; Yang, Yongheng; Zhang, Xiaobin

2017-01-01

Resonant poles of LCL filters may challenge the entire system stability especially in digital-controlled Pulse Width Modulation (PWM) inverters. In order to tackle the resonance issues, many active damping solutions have been reported. For instance, a notch filter can be employed to damp the reso......Resonant poles of LCL filters may challenge the entire system stability especially in digital-controlled Pulse Width Modulation (PWM) inverters. In order to tackle the resonance issues, many active damping solutions have been reported. For instance, a notch filter can be employed to damp...... the resonance, where the notch frequency should be aligned exactly to the resonant frequency of the LCL filter. However, parameter variations of the LCL filter as well as the time delay appearing in digital control systems will induce resonance drifting, and thus break this alignment, possibly deteriorating...... the original damping. In this paper, the effectiveness of the notch filter based active damping is firstly explored, considering the drifts of the resonant frequency. It is revealed that, when the resonant frequency drifts away from its nominal value, the phase lead or lag introduced by the notch filter may...

Use of glycerol-preserved corneas for corneal transplants

Directory of Open Access Journals (Sweden)

Neeti Gupta

2017-01-01

Full Text Available Purpose: This study was carried out to see the results of glycerol-preserved cornea (GPC in emergency situation when fresh corneal tissue was not available. The aim was to study the outcome of corneal transplantation using GPC. Methods: This was a retrospective study. The medical records of all the patients were reviewed, who underwent keratoplasty using “GPC” during the period from October 2011 to December 2015. The indication of keratoplasty, duration of preservation of the GPC, and its outcome were analyzed. Descriptive statistics were applied. Results: Out of the 222 penetrating keratoplasty (PKP performed over the study period, the GPC was used in 34 patients (males = 31, 91.2% aged 15–74 years. Therapeutic keratoplasty was performed in all cases in this cohort except one in which tectonic keratoplasty was done. The primary indication of PKP (91.2% was infectious keratitis. Of these, 20 (64.5% patients presented with perforated corneal ulcers. Post-PKP, ocular anatomy was preserved in 91.2%, and visual acuity of perception of light positive and accurate projection of rays in all the quadrants was obtained in 76.5% cases. Complications included glaucoma (n = 12, 35.1%, phthisis bulbi (n = 2, 5.9%, and graft reinfection and endophthalmitis after PKP (n = 1, 2.9%. The secondary procedure post-GPC and PKP were trabeculectomy with mitomycin C (n = 7, 58.3% in patients not controlled on topical antiglaucoma medication. Optical keratoplasty was performed in (n = 3 8.8% patients and triple procedure in (n = 2 5.8% patients with good visual acuity postprocedure. Conclusions: Acellular GPCs are useful in emergency keratoplasty to avoid loss of vision and can save the eye.

The use of Wavelight® Contoura to create a uniform cornea: the LYRA protocol. Part 3: the results of 50 treated eyes

Directory of Open Access Journals (Sweden)

Motwani M

2017-05-01

Full Text Available Manoj Motwani Motwani LASIK Institute, San Diego, CA, USA Purpose: To demonstrate how using the Wavelight Contoura measured astigmatism and axis eliminates corneal astigmatism and creates uniformly shaped corneas. Patients and methods: A retrospective analysis was conducted of the first 50 eyes to have bilateral full WaveLight® Contoura LASIK correction of measured astigmatism and axis (vs conventional manifest refraction, using the Layer Yolked Reduction of Astigmatism Protocol in all cases. All patients had astigmatism corrected, and had at least 1 week of follow-up. Accuracy to desired refractive goal was assessed by postoperative refraction, aberration reduction via calculation of polynomials, and postoperative visions were analyzed as a secondary goal. Results: The average difference of astigmatic power from manifest to measured was 0.5462D (with a range of 0–1.69D, and the average difference of axis was 14.94° (with a range of 0°–89°. Forty-seven of 50 eyes had a goal of plano, 3 had a monovision goal. Astigmatism was fully eliminated from all but 2 eyes, and 1 eye had regression with astigmatism. Of the eyes with plano as the goal, 80.85% were 20/15 or better, and 100% were 20/20 or better. Polynomial analysis postoperatively showed that at 6.5 mm, the average C3 was reduced by 86.5% and the average C5 by 85.14%. Conclusions: Using WaveLight® Contoura measured astigmatism and axis removes higher order aberrations and allows for the creation of a more uniform cornea with accurate removal of astigmatism, and reduction of aberration polynomials. WaveLight® Contoura successfully links the refractive correction layer and aberration repair layer using the Layer Yolked Reduction of Astigmatism Protocol to demonstrate how aberration removal can affect refractive correction. Keywords: WaveLight Contoura, topographic guided ablation, LASIK, PRK, uniform cornea, Contoura with LYRA Protocol, measured astigmatism

FULL SCALE REGENERABLE HEPA FILTER DESIGN USING SINTERED METAL FILTER ELEMENTS

International Nuclear Information System (INIS)

Gil Ramos; Kenneth Rubow; Ronald Sekellick

2002-01-01

A Department of Energy funded contract involved the development of porous metal as a HEPA filter, and the subsequent design of a full-scale regenerable HEPA filtration system (RHFS). This RHFS could replace the glass fiber HEPA filters currently being used on the high level waste (HLW) tank ventilation system with a system that would be moisture tolerant, durable, and cleanable in place. The origins of the contract are a 1996 investigation at the Savannah River Technology Center (SRTC) regarding the use of porous metal as a HEPA filter material. This contract was divided into Phases I, IIA and IIB. Phase I of the contract evaluated simple filter cylinders in a simulated High Level Waste (HLW) environment and the ability to clean and regenerate the filter media after fouling. Upon the successful completion of Phase I, Phase IIA was conducted, which included lab scale prototype testing and design of a full-scale system. The work completed under Phase IIA included development of a full-scale system design, development of a filter media meeting the HEPA filtration efficiency that would also be regenerable using prescribed cleaning procedures, and the testing of a single element system prototype at Savannah River. All contract objectives were met. The filter media selected was a nickel material already under development at Mott, which met the HEPA filtration efficiency standard. The Mott nickel media met and exceeded the HEPA requirement, providing 99.99% removal against a requirement of 99.97%. Double open-ended elements of this media were provided to the Savannah River Test Center for HLW simulation testing in the single element prototype filter. These elements performed well and further demonstrated the practicality of a metallic media regenerable HEPA filter system. An evaluation of the manufacturing method on many elements demonstrated the reproducibility to meet the HEPA filtration requirement. The full-scale design of the Mott RHFS incorporated several important

Filter Paper: Solution to High Self-Attenuation Corrections in HEPA Filter Measurements

International Nuclear Information System (INIS)

Oberer, R.B.; Harold, N.B.; Gunn, C.A.; Brummett, M.; Chaing, L.G.

2005-01-01

An 8 by 8 by 6 inch High Efficiency Particulate Air (HEPA) filter was measured as part of a uranium holdup survey in June of 2005 as it has been routinely measured every two months since 1998. Although the survey relies on gross gamma count measurements, this was one of a few measurements that had been converted to a quantitative measurement in 1998. The measurement was analyzed using the traditional Generalized Geometry Holdup (GGH) approach, using HMS3 software, with an area calibration and self-attenuation corrected with an empirical correction factor of 1.06. A result of 172 grams of 235 U was reported. The actual quantity of 235 U in the filter was approximately 1700g. Because of this unusually large discrepancy, the measurement of HEPA filters will be discussed. Various techniques for measuring HEPA filters will be described using the measurement of a 24 by 24 by 12 inch HEPA filter as an example. A new method to correct for self attenuation will be proposed for this measurement Following the discussion of the 24 by 24 by 12 inch HEPA filter, the measurement of the 8 by 8 by 6 inch will be discussed in detail

High flow ceramic pot filters.

Science.gov (United States)

van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

2017-11-01

Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

Updating the OMERACT filter

DEFF Research Database (Denmark)

Wells, George; Beaton, Dorcas E; Tugwell, Peter

2014-01-01

The "Discrimination" part of the OMERACT Filter asks whether a measure discriminates between situations that are of interest. "Feasibility" in the OMERACT Filter encompasses the practical considerations of using an instrument, including its ease of use, time to complete, monetary costs......, and interpretability of the question(s) included in the instrument. Both the Discrimination and Reliability parts of the filter have been helpful but were agreed on primarily by consensus of OMERACT participants rather than through explicit evidence-based guidelines. In Filter 2.0 we wanted to improve this definition...

Filters in nuclear facilities

International Nuclear Information System (INIS)

Berg, K.H.; Wilhelm, J.G.

1985-01-01

The topics of the nine papers given include the behavior of HEPA filters during exposure to air flows of high humidity as well as of high differential pressure, the development of steel-fiber filters suitable for extreme operating conditions, and the occurrence of various radioactive iodine species in the exhaust air from boiling water reactors. In an introductory presentation the German view of the performance requirements to be met by filters in nuclear facilities as well as the present status of filter quality assurance are discussed. (orig.) [de

Nanofiber Filters Eliminate Contaminants

Science.gov (United States)

2009-01-01

With support from Phase I and II SBIR funding from Johnson Space Center, Argonide Corporation of Sanford, Florida tested and developed its proprietary nanofiber water filter media. Capable of removing more than 99.99 percent of dangerous particles like bacteria, viruses, and parasites, the media was incorporated into the company's commercial NanoCeram water filter, an inductee into the Space Foundation's Space Technology Hall of Fame. In addition to its drinking water filters, Argonide now produces large-scale nanofiber filters used as part of the reverse osmosis process for industrial water purification.

Simon-nitinol filter

International Nuclear Information System (INIS)

Simon, M.; Kim, D.; Porter, D.H.; Kleshinski, S.

1989-01-01

This paper discusses a filter that exploits the thermal shape-memory properties of the nitinol alloy to achieve an optimized filter shape and a fine-bore introducer. Experimental methods and materials are given and results are analyzed

GRIM-Filter: Fast seed location filtering in DNA read mapping using processing-in-memory technologies.

Science.gov (United States)

Kim, Jeremie S; Senol Cali, Damla; Xin, Hongyi; Lee, Donghyuk; Ghose, Saugata; Alser, Mohammed; Hassan, Hasan; Ergin, Oguz; Alkan, Can; Mutlu, Onur

2018-05-09

Seed location filtering is critical in DNA read mapping, a process where billions of DNA fragments (reads) sampled from a donor are mapped onto a reference genome to identify genomic variants of the donor. State-of-the-art read mappers 1) quickly generate possible mapping locations for seeds (i.e., smaller segments) within each read, 2) extract reference sequences at each of the mapping locations, and 3) check similarity between each read and its associated reference sequences with a computationally-expensive algorithm (i.e., sequence alignment) to determine the origin of the read. A seed location filter comes into play before alignment, discarding seed locations that alignment would deem a poor match. The ideal seed location filter would discard all poor match locations prior to alignment such that there is no wasted computation on unnecessary alignments. We propose a novel seed location filtering algorithm, GRIM-Filter, optimized to exploit 3D-stacked memory systems that integrate computation within a logic layer stacked under memory layers, to perform processing-in-memory (PIM). GRIM-Filter quickly filters seed locations by 1) introducing a new representation of coarse-grained segments of the reference genome, and 2) using massively-parallel in-memory operations to identify read presence within each coarse-grained segment. Our evaluations show that for a sequence alignment error tolerance of 0.05, GRIM-Filter 1) reduces the false negative rate of filtering by 5.59x-6.41x, and 2) provides an end-to-end read mapper speedup of 1.81x-3.65x, compared to a state-of-the-art read mapper employing the best previous seed location filtering algorithm. GRIM-Filter exploits 3D-stacked memory, which enables the efficient use of processing-in-memory, to overcome the memory bandwidth bottleneck in seed location filtering. We show that GRIM-Filter significantly improves the performance of a state-of-the-art read mapper. GRIM-Filter is a universal seed location filter that can be

Clear aligners in orthodontic treatment.

Science.gov (United States)

Weir, T

2017-03-01

Since the introduction of the Tooth Positioner (TP Orthodontics) in 1944, removable appliances analogous to clear aligners have been employed for mild to moderate orthodontic tooth movements. Clear aligner therapy has been a part of orthodontic practice for decades, but has, particularly since the introduction of Invisalign appliances (Align Technology) in 1998, become an increasingly common addition to the orthodontic armamentarium. An internet search reveals at least 27 different clear aligner products currently on offer for orthodontic treatment. The present paper will highlight the increasing popularity of clear aligner appliances, as well as the clinical scope and the limitations of aligner therapy in general. Further, the paper will outline the differences between the various types of clear aligner products currently available. © 2017 Australian Dental Association.

Filter cake breaker systems

Energy Technology Data Exchange (ETDEWEB)

Garcia, Marcelo H.F. [Poland Quimica Ltda., Duque de Caxias, RJ (Brazil)

2004-07-01

Drilling fluids filter cakes are based on a combination of properly graded dispersed particles and polysaccharide polymers. High efficiency filter cakes are formed by these combination , and their formation on wellbore walls during the drilling process has, among other roles, the task of protecting the formation from instantaneous or accumulative invasion of drilling fluid filtrate, granting stability to well and production zones. Filter cake minimizes contact between drilling fluid filtrate and water, hydrocarbons and clay existent in formations. The uniform removal of the filter cake from the entire interval is a critical factor of the completion process. The main methods used to breaking filter cake are classified into two groups, external or internal, according to their removal mechanism. The aim of this work is the presentation of these mechanisms as well their efficiency. (author)

17 CFR 39.4 - Procedures for implementing derivatives clearing organization rules and clearing new products.

Science.gov (United States)

2010-04-01

... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Procedures for implementing derivatives clearing organization rules and clearing new products. 39.4 Section 39.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION DERIVATIVES CLEARING ORGANIZATIONS § 39.4 Procedures for...

Clear cell chondrosarcoma

Energy Technology Data Exchange (ETDEWEB)

Kumar, R.; David, R.; Cierney, G. III

1985-01-01

The clinical, radiologic, and histopathologic features of three cases of clear cell chondrosarcoma are described. On radiographs, this rather benign-appearing tumor resembles a chondroblastoma when it occurs at the end of a long bone, and may occasionally show a calcified matrix. However, it has distinctive tumor cells with a centrally placed vesicular nucleus surrounded by clear cytoplasm. The lesion has a low-grade malignancy and is amenable to en bloc surgical resection, which results in a much better prognosis than that of conventional chondrosarcoma.

Two-dimensional filtering of SPECT images using the Metz and Wiener filters

International Nuclear Information System (INIS)

King, M.A.; Schwinger, R.B.; Penney, B.C.; Doherty, P.W.

1984-01-01

Presently, single photon emission computed tomographic (SPECT) images are usually reconstructed by arbitrarily selecting a one-dimensional ''window'' function for use in reconstruction. A better method would be to automatically choose among a family of two-dimensional image restoration filters in such a way as to produce ''optimum'' image quality. Two-dimensional image processing techniques offer the advantages of a larger statistical sampling of the data for better noise reduction, and two-dimensional image deconvolution to correct for blurring during acquisition. An investigation of two such ''optimal'' digital image restoration techniques (the count-dependent Metz filter and the Wiener filter) was made. They were applied both as two-dimensional ''window'' functions for preprocessing SPECT images, and for filtering reconstructed images. Their performance was compared by measuring image contrast and per cent fractional standard deviation (% FSD) in multiple-acquisitions of the Jaszczak SPECT phantom at two different count levels. A statistically significant increase in image contrast and decrease in % FSD was observed with these techniques when compared to the results of reconstruction with a ramp filter. The adaptability of the techniques was manifested in a lesser % reduction in % FSD at the high count level coupled with a greater enhancement in image contrast. Using an array processor, processing time was 0.2 sec per image for the Metz filter and 3 sec for the Wiener filter. It is concluded that two-dimensional digital image restoration with these techniques can produce a significant increase in SPECT image quality

Remotely operated top loading filter housing

International Nuclear Information System (INIS)

Ross, M.J.; Carter, J.A.

1989-01-01

A high-efficiency particulate air (HEPA) filter system was developed for the Fuel Processing Facility at the Idaho Chemical Processing Plant. The system utilizes commercially available HEPA filters and allows in-cell filters to be maintained using operator-controlled remote handling equipment. The remote handling tasks include transport of filters before and after replacement, removal and replacement of the filter from the housing, and filter containment

Reconfigurable Mixed Mode Universal Filter

Directory of Open Access Journals (Sweden)

Neelofer Afzal

2014-01-01

Full Text Available This paper presents a novel mixed mode universal filter configuration capable of working in voltage and transimpedance mode. The proposed single filter configuration can be reconfigured digitally to realize all the five second order filter functions (types at single output port. Other salient features of proposed configuration include independently programmable filter parameters, full cascadability, and low sensitivity figure. However, all these features are provided at the cost of quite large number of active elements. It needs three digitally programmable current feedback amplifiers and three digitally programmable current conveyors. Use of six active elements is justified by introducing three additional reduced hardware mixed mode universal filter configurations and its comparison with reported filters.

The statistical bandwidth of Butterworth filters

Science.gov (United States)

Davy, J. L.; Dunn, I. P.

1987-06-01

The precision of standard architectural acoustic measurements is a function of the statistical bandwidth of the band pass filters used in the measurements. The International and United States Standards on octave and fractional octave-band filters which specify the band pass filters used in architectural acoustics measurements give the effective bandwidth, but unfortunately not the statistical bandwidth of the filters. Both these Standards are currently being revised and both revisions require the use of Butterworth filter characteristics. In this paper it is shown theoretically that the ratio of statistical bandwidth to effective bandwidth for an nth order Butterworth band pass filter is {2n}/{(2n-1)}. This is verified experimentally for third-octave third-order Butterworth band pass filters. It is also shown experimentally that this formula is approximately correct for some non-Butterworth third-octave third-order band pass filters. Because of the importance of Butterworth filters in the revised Standards, the theory of Butterworth filters is reviewed and the formulae for Butterworth filters given in both revised Standards are derived.

EMI filter design

CERN Document Server

Ozenbaugh, Richard Lee

2011-01-01

With today's electrical and electronics systems requiring increased levels of performance and reliability, the design of robust EMI filters plays a critical role in EMC compliance. Using a mix of practical methods and theoretical analysis, EMI Filter Design, Third Edition presents both a hands-on and academic approach to the design of EMI filters and the selection of components values. The design approaches covered include matrix methods using table data and the use of Fourier analysis, Laplace transforms, and transfer function realization of LC structures. This edition has been fully revised

21 CFR 211.72 - Filters.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Filters. 211.72 Section 211.72 Food and Drugs FOOD... shall not release fibers into such products. Fiber-releasing filters may be used when it is not possible to manufacture such products without the use of these filters. If use of a fiber-releasing filter is...

UV Fluorescence Photography of Works of Art : Replacing the Traditional UV Cut Filters with Interference Filters

Directory of Open Access Journals (Sweden)

Luís BRAVO PEREIRA

2010-09-01

Full Text Available For many years filters like the Kodak Wratten E series, or the equivalent Schneider B+W 415, were used as standard UV cut filters, necessary to obtain good quality on UV Fluorescence photography. The only problem with the use of these filters is that, when they receive the UV radiation that they should remove, they present themselves an internal fluorescence as side effect, that usually reduce contrast and quality on the final image. This article presents the results of our experiences on using some innovative filters, that appeared available on the market in recent years, projected to adsorb UV radiation even more efficiently than with the mentioned above pigment based standard filters: the interference filters for UV rejection (and, usually, for IR rejection too manufactured using interference layers, that present better results than the pigment based filters. The only problem with interference filters type is that they are sensitive to the rays direction and, because of that, they are not adequate to wide-angle lenses. The internal fluorescence for three filters: the B+W 415 UV cut (equivalent to the Kodak Wratten 2E, pigment based, the B+W 486 UV IR cut (an interference type filter, used frequently on digital cameras to remove IR or UV and the Baader UVIR rejection filter (two versions of this interference filter were used had been tested and compared. The final quality of the UV fluorescence images seems to be of a superior quality when compared to the images obtained with classic filters.

Novel Simplex Unscented Transform and Filter

Institute of Scientific and Technical Information of China (English)

Wan-Chun Li; Ping Wei; Xian-Ci Xiao

2008-01-01

In this paper, a new simplex unscented transform (UT) based Schmidt orthogonal algorithm and a new filter method based on this transform are proposed. This filter has less computation consumption than UKF (unscented Kalman filter), SUKF (simplex unscented Kalman filter) and EKF (extended Kalman filter). Computer simulation shows that this filter has the same performance as UKF and SUKF, and according to the analysis of the computational requirements of EKF, UKF and SUKF, this filter has preferable practicality value. Finally, the appendix shows the efficiency for this UT.

Robust Ensemble Filtering and Its Relation to Covariance Inflation in the Ensemble Kalman Filter

KAUST Repository

Luo, Xiaodong; Hoteit, Ibrahim

2011-01-01

A robust ensemble filtering scheme based on the H∞ filtering theory is proposed. The optimal H∞ filter is derived by minimizing the supremum (or maximum) of a predefined cost function, a criterion different from the minimum variance used

OPTIMIZATION OF ADVANCED FILTER SYSTEMS; TOPICAL

International Nuclear Information System (INIS)

R.A. Newby; G.J. Bruck; M.A. Alvin; T.E. Lippert

1998-01-01

Reliable, maintainable and cost effective hot gas particulate filter technology is critical to the successful commercialization of advanced, coal-fired power generation technologies, such as IGCC and PFBC. In pilot plant testing, the operating reliability of hot gas particulate filters have been periodically compromised by process issues, such as process upsets and difficult ash cake behavior (ash bridging and sintering), and by design issues, such as cantilevered filter elements damaged by ash bridging, or excessively close packing of filtering surfaces resulting in unacceptable pressure drop or filtering surface plugging. This test experience has focused the issues and has helped to define advanced hot gas filter design concepts that offer higher reliability. Westinghouse has identified two advanced ceramic barrier filter concepts that are configured to minimize the possibility of ash bridge formation and to be robust against ash bridges should they occur. The ''inverted candle filter system'' uses arrays of thin-walled, ceramic candle-type filter elements with inside-surface filtering, and contains the filter elements in metal enclosures for complete separation from ash bridges. The ''sheet filter system'' uses ceramic, flat plate filter elements supported from vertical pipe-header arrays that provide geometry that avoids the buildup of ash bridges and allows free fall of the back-pulse released filter cake. The Optimization of Advanced Filter Systems program is being conducted to evaluate these two advanced designs and to ultimately demonstrate one of the concepts in pilot scale. In the Base Contract program, the subject of this report, Westinghouse has developed conceptual designs of the two advanced ceramic barrier filter systems to assess their performance, availability and cost potential, and to identify technical issues that may hinder the commercialization of the technologies. A plan for the Option I, bench-scale test program has also been developed based

Cost/benefit evaluation of electrofibrous air filters

International Nuclear Information System (INIS)

Bergman, W.; Kuhl, W.; Biermann, A.; Lum, B.

1986-01-01

Experimental electric air filters based on the principle of superimposing an electric field over conventional fibrous air filters have been developed. The different experimental electric filters described in this report include prefilters for use in glove boxes and in ventilation systems, re-circulating air filters, electric HEPA filters, and high efficiency, high temperature air filters. In each case the large improvement in filter efficiency that occurs when a mechanical filter is electrified is demonstrated. Also a significant increase in the particle loading capacity of filters in many of our evaluations is demonstrated. Both laboratory and field test results are presented. This paper also demonstrates that the performance of all of our electric filter designs, except one, can be matched by conventional mechanical air filters and usually at a lower cost. The one exception is the high temperature, high efficiency electric air filter. In that case there is no mechanical filter media that can match the performance of the electric air filter. Our findings show that electric air filters are only cost effective compared to mechanical air filters when the performance of the mechanical air filter cannot be further improved by mechanical means. (author)

Washing method of filter

International Nuclear Information System (INIS)

Izumidani, Masakiyo; Tanno, Kazuo.

1978-01-01

Purpose: To enable automatic filter operation and facilitate back-washing operation by back-washing filters used in a bwr nuclear power plant utilizing an exhaust gas from a ventilator or air conditioner. Method: Exhaust gas from an exhaust pipe of an ventilator or air conditioner is pressurized in a compressor and then introduced in a back-washing gas tank. Then, the exhaust gas pressurized to a predetermined pressure is blown from the inside to the outside of a filter to thereby separate impurities collected on the filter elements and introduce them to a waste tank. (Furukawa, Y.)

Auditory filters at low-frequencies

DEFF Research Database (Denmark)

Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Møller, Henrik

2009-01-01

-ear transfer function), the asymmetry of the auditory filter changed from steeper high-frequency slopes at 1000 Hz to steeper low-frequency slopes below 100 Hz. Increasing steepness at low-frequencies of the middle-ear high-pass filter is thought to cause this effect. The dynamic range of the auditory filter...... was found to steadily decrease with decreasing center frequency. Although the observed decrease in filter bandwidth with decreasing center frequency was only approximately monotonic, the preliminary data indicates the filter bandwidth does not stabilize around 100 Hz, e.g. it still decreases below...

The history of ceramic filters.

Science.gov (United States)

Fujishima, S

2000-01-01

The history of ceramic filters is surveyed. Included is the history of piezoelectric ceramics. Ceramic filters were developed using technology similar to that of quartz crystal and electro-mechanical filters. However, the key to this development involved the theoretical analysis of vibration modes and material improvements of piezoelectric ceramics. The primary application of ceramic filters has been for consumer-market use. Accordingly, a major emphasis has involved mass production technology, leading to low-priced devices. A typical ceramic filter includes monolithic resonators and capacitors packaged in unique configurations.

Experimental Study of Generalized Subspace Filters for the Cocktail Party Situation

DEFF Research Database (Denmark)

Christensen, Knud Bank; Christensen, Mads Græsbøll; Boldt, Jesper B.

2016-01-01

This paper investigates the potential performance of generalized subspace filters for speech enhancement in cocktail party situations with very poor signal/noise ratio, e.g. down to -15 dB. Performance metrics output signal/noise ratio, signal/ distortion ratio, speech quality rating and speech...... intelligibility rating are mapped as functions of two algorithm parameters, revealing clear trade-off options between noise, distortion and subjective performances and a recommended choice of trade-off. Given sufficiently good noise statistics, SNR improvements around 20 dB as well as PESQ quality and STOI...

Group Lifting Structures For Multirate Filter Banks, II: Linear Phase Filter Banks

Energy Technology Data Exchange (ETDEWEB)

Brislawn, Christopher M [Los Alamos National Laboratory

2008-01-01

The theory of group lifting structures is applied to linear phase lifting factorizations for the two nontrivial classes of two-channel linear phase perfect reconstruction filter banks, the whole-and half-sample symmetric classes. Group lifting structures defined for the reversible and irreversible classes of whole-and half-sample symmetric filter banks are shown to satisfy the hypotheses of the uniqueness theorem for group lifting structures. It follows that linear phase lifting factorizations of whole-and half-sample symmetric filter banks are therefore independent of the factorization methods used to compute them. These results cover the specification of user-defined whole-sample symmetric filter banks in Part 2 of the ISO JPEG 2000 standard.

77 FR 12896 - Self-Regulatory Organizations; Midwest Clearing Corporation; Order Cancelling Clearing Agency...

Science.gov (United States)

2012-03-02

... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-66458; File No. 600-9] Self-Regulatory Organizations; Midwest Clearing Corporation; Order Cancelling Clearing Agency Registration February 24, 2012. I... Act provides that in the event any self- regulatory organization is no longer in existence or has...

Biological treatment of wastewaters from a dye manufacturing company using a trickling filter

International Nuclear Information System (INIS)

Kornaros, M.; Lyberatos, G.

2006-01-01

The aim of this work was to assess the effectiveness of a biological trickling filter for the treatment of wastewaters produced by a company manufacturing organic dyes and varnishes. The combined wastewater effluent was fed to a pilot-scale trickling filter in two feeding modes, continuously and as a sequencing batch reactor (SBR). The biodegradability of the diluted wastewaters that were subjected to physicochemical treatment, using Ca(OH) 2 and FeSO 4 , was initially studied using a continuously operated trickling filter. The system efficiency ranged up to 60-70% for a hydraulic loading of 1.1 m 3 /m 2 day and up to 80-85% for a hydraulic loading 0.6 m 3 /m 2 day. A stable chemical oxygen demand (COD) removal efficiency of 60-70% was achieved even in the case of undiluted wastewater at a hydraulic loading of 1.1 m 3 /m 2 day. The effectiveness of biological treatment of a mixture of the company's main wastewater streams was also examined. The microorganisms developed in the trickling filter were able to efficiently remove COD levels up to 36,000 mg/L, under aerobic conditions at pH values between 5.5 and 8.0. Depending on the operating conditions of the system, about 30-60% of the total COD removal was attributed to air stripping caused by the air supply at the bottom of the filter, whereas the rest of the COD was clearly removed through biological action. The proposed biological treatment process based on a trickling filter, which was operated either continuously or even better in an SBR mode, appears as a promising pretreatment step for coping with dye manufacturing wastewaters in terms of removing a significant portion of the organic content

A Novel Design of Sparse Prototype Filter for Nearly Perfect Reconstruction Cosine-Modulated Filter Banks

Directory of Open Access Journals (Sweden)

Wei Xu

2018-05-01

Full Text Available Cosine-modulated filter banks play a major role in digital signal processing. Sparse FIR filter banks have lower implementation complexity than full filter banks, while keeping a good performance level. This paper presents a fast design paradigm for sparse nearly perfect-reconstruction (NPR cosine-modulated filter banks. First, an approximation function is introduced to reduce the non-convex quadratically constrained optimization problem to a linearly constrained optimization problem. Then, the desired sparse linear phase FIR prototype filter is derived through the orthogonal matching pursuit (OMP performed under the weighted l 2 norm. The simulation results demonstrate that the proposed scheme is an effective paradigm to design sparse NPR cosine-modulated filter banks.

Common genetic variants near the Brittle Cornea Syndrome locus ZNF469 influence the blinding disease risk factor central corneal thickness.